Full text of "Aviation engines; design--construction--operation and repair; a complete, practical treatise outlining clearly the elemtns of internal combustion engineering with special reference to the design, construction, operation and repair of airplane power plants; also the auxiliary engine systems, such as lubrication, carburetion, ignition and cooling. It includes complete instructions for engine repairing and sytematic location of troubles, tool equipment and use of tools, also outlines with the latest mechanical processes"

GIFT OF
/~/ I// //'/fan

A c J

Library

JUST PUBLISHED

AVIATION ENGINES. Their Design, Construction,
Operation and Repair.

By Lieut. VICTOR W. PAGE, Aviation Section, S.C.U.S.R.

A practical work containing valuable instructions for aviation
students, mechanicians, squadron engineering officers and all inter-
ested in the "construction and upkeep of airplane power plants.
576 octavo pages. 250 illustrations. Price $3.00.

AVIATION CHART, or the Location of Airplane Power
Plant Troubles Made Easy.

By Lieut. VICTOR W. PAGE, A.S., &C.U.S.R.

A large chart outlining all parts of i typical airplane power plant,
showing the points where trouble is apt to occur and suggesting
remedies for the common defects. Intended especially for aviators
and aviation mechanics on school and field duty. Price 50 cents.

GLOSSARY OF AVIATION TERMS.

Compiled by Lieuts. VICTOR W. PAGE, A.S., S.C.U.S.R. and
PAUL MONTARIOL of the French Flying Corps on duty at
Signal Corps Aviation School, Mineola, L. I.
A complete glossary of practically all terms used in aviation,
having lists in both French and English, with equivalents in either
language. A very valuable book for all who are about to leave
for duty overseas. Price, cloth, $1.00.

THE NORMAN W. HENLEY PUBLISHING COMPANY
2 WEST 45TH ST., NEW YORK

Rocker Lever

Cam Shaft- ",

Oil Jacket

Inlet Pipe "" '->.

Fulcrum

^Regulating Screw
s'Key , -Valve Spring Collar

' ,- Valve Spring

Valve Stem

Valve Stem Guide
'"-Exhaust Pipe

Contact Breaker

Safety Gas-'''
Wrist Pin-"''
Connecting Rod "

**** *"

CrankShaft-''

Crank Pin '"

Bearing Box-'"'

Sump-*'''

; / ^Upper Half Case
-Lower Half Case

"' Drain Plug orNuf

Drain Cock--"'

A.6.HA6STROM N.Y.

Part Sectional View of Hall-Scott Airplane Motor, Showing
Principal Parts.

AVIATION ENGINES

Design Construction Operation and Repair

A COMPLETE, PRACTICAL TREATISE OUTLINING CLEARLY
THE ELEMENTS OF INTERNAL COMBUSTION ENGINEERING
WITH SPECIAL REFERENCE TO THE DESIGN, CONSTRUC-
TION, OPERATION AND REPAIR OF AIRPLANE POWER
PLANTS; ALSO THE AUXILIARY ENGINE SYSTEMS, SUCH
AS LUBRICATION, CARBURETION, IGNITION AND COOLING.

IT INCLUDES COMPLETE INSTRUCTIONS FOR ENGINE

REPAIRING AND SYSTEMATIC LOCATION OF TROUBLES,

TOOL EQUIPMENT AND USE OF TOOLS, ALSO OUTLINES

THE LATEST MECHANICAL PROCESSES.

FIRST LIEUT. VICTOR W. PAGE, A. S. S. C., U. S. R.

Assistant Engineering Officer, Signal Corps Aviation School, Mineola, L. I.
Author of "The Modern Gasoline Automobile," Etc.

CONTAINS VALUABLE INSTRUCTIONS FOR ALL AVIATION STUDENTS, MECH-
ANICIANS, SQUADRON ENGINEERING OFFICERS AND ALL INTERESTED IN
THE CONSTRUCTION AND UPKEEP OF AIRPLANE POWER PLANTS.

NEW YORK

THE NORMAN W. HENLEY PUBLISHING COMPANY

2 WEST 45th STREET
1918

Engineering
Library

COPYRIGHTED, 1917

THE NORMAN W. HENLEY PUBLISHING Co.

PRINTED IN U. S. A.

THIRD IMPRESSION

ALL ILLUSTRATIONS IN THIS BOOK HAVE BEEN
SPECIALLY MADE BY THE PUBLISHERS, AND THEIR
USE, WITHOUT PERMISSION, IS STRICTLY PROHIBITED

PRESS OF

BRAUNWORTH & CO.

BOOK MANUFACTURERS

BROOKLYN. N, Yo

PREFACE

IN presenting this treatise on "Aviation Engines,"
the writer realizes that the rapidly developing art makes
it difficult to outline all latest forms or describe all
current engineering practice. This exposition has been
prepared primarily for instruction purposes and is adapted
for men in the Aviation Section, Signal Corps, and
students who wish to become aviators or aviation mech-
anicians. Every effort has been made to have the engi-
neering information accurate, but owing to the diversity
of authorities consulted and use of data translated from
foreign language periodicals, it is expected that some
slight errors will be present. The writer wishes to ac-
knowledge his indebtedness to such firms as the Curtiss
Aeroplane and Motor Co., Hall-Scott Company, Thomas-
Morse Aircraft Corporation and General Vehicle Com-
pany for photographs and helpful descriptive matter.
Special attention has been paid to instructions on tool
equipment, use of tools, trouble "shooting" and -engine
repairs, as it is on these points that the average aviation
student is weakest. Only such theoretical consideration
of thermo-dynamics as was deemed absolutely necessary
to secure a proper understanding of engine action after
consulting several instructors is included, the writer's
efforts having been confined to the preparation of a
practical series of instructions that would be of the
greatest value to those who need a diversified knowledge
of internal-combustion engine operation and repair, and

398185

10 Preface

who must acquire it quickly. The engines, described and
illustrated are all practical forms that have been fitted to
airplanes capable of making flights and may be considered
fairly representative of the present state of the art.

VICTOR W. PAGE,
1st Lieut. A. S. S. C., U. S. R.

MlNEOLA, L. I.,

March, 1918.

CONTENTS

CHAPTER I

PAGES

Brief Consideration of Aircraft Types Essential Requirements of Aerial
Motors Aviation Engines Must Be Light Factors Influencing
Power Needed Why Explosive Motors Are Best Historical Main
Types of Internal Combustion Engines 17-36

CHAPTER II

Operating Principles of Two- and Four-Stroke Engines Four-cycle
Action Two-cycle Action Comparing Two- and Four-cycle Types
Theory of Gas and Gasoline Engine Early Gas-Engine Forms
Isothermal Law Adiabatic Law Temperature Computations
Heat and Its Work Conversion of Heat to Power Requisites for
Best Power Effect 37-59

CHAPTER III

Efficiency of Internal Combustion Engines Various Measures of Effi-
ciency Temperatures and Pressures Factors Governing Economy
Losses in Wall Cooling "Value of Indicator Cards Compression
in Explosive Motors Factors Limiting Compression Causes of
Heat Losses and Inefficiency Heat Losses to Cooling Water . 60-79

CHAPTER IV

Engine Parts and Functions Why Multiple Cylinder Engines Are Best
Describing Sequence of Operations Simple Engines Four and
Six Cylinder Vertical Tandem Engines Eight and Twelve Cylinder
V Engines Radial Cylinder Arrangement Rotary Cylinder
Forms . 80-109

CHAPTER V

Properties of Liquid Fuels Distillates of Crude Petroleum Principles
of Carburetion Outlined Air Needed to Burn Gasoline What a
Carburetor Should Do Liquid Fuel Storage and Supply Vacuum
Fuel Feed Early Vaporizer Forms Development of Float

12 Contents

PAGES

Feed Carburetor Maybach's Early Design Concentric Float and
Jet Type Sehebler Carburetor Claudel Carburetor Stewart
Metering Pin Type Multiple Nozzle Vaporizers Two-Stage Car-
buretor Master Multiple Jet Type Compound Nozzle Zenith Car-
buretor Utility of Gasoline Strainers Intake Manifold Design and
Construction Compensating for Various Atmospheric Conditions .
How High Altitude Affects Power The Diesel System Notes on
Carburetor Installation Notes on Carburetor Adjustment . 110-154

CHAPTER VI

Early Ignition Systems Electrical Ignition Best Fundamentals of
Magnetism Outlined Forms of Magneto Zones of Magnetic In-
fluence How Magnets are Made Electricity and Magnetism Be-
lated Basic Principles of Magneto Action Essential Parts of
Magneto and Functions Transformer Coil Systems True High
Tension Type -The Berling Magneto Timing and Care The Dixie
Magneto Spark-Plug Design and Application Two-Spark Ignition
Special Airplane Plug . 155-200

CHAPTER VII

Why Lubrication Is Necessary Friction Defined Theory of Lubrica-
tion Derivation of Lubricants Properties of Cylinder Oils Fac-
tors Influencing Lubrication System Selection Gnome Type Engines
Use Castor Oil Hall-Scott Lubrication System Oil Supply by
Constant Level Splash System Dry Crank-Case System Best for
Airplane Engines Why Cooling Systems Are Necessary Cooling
Systems Generally Applied Cooling by Positive Pump Circulation
Thermo-Syphon System Direct Air-Cooling Methods Air-
Cooled Engine Design Considerations 201-232

CHAPTER VIII

Methods of Cylinder Construction Block Castings Influence on Crank-
Shaft Design Combustion Chamber Design Bore and Stroke Eatio
Meaning of Piston Speed Advantage of Off-Set Cylinders
Valve Location of Vital Import Valve Installation Practice Valve
Design and Construction Valve Operation Methods of Driving
Cam-Shaft Valve Springs Valve Timing Blowing Back Lead
Given Exhaust Valve Exhaust Closing, Inlet Opening Closing the
Inlet Valve Time of Ignition How an Engine is Timed Gnome
"Monosoupape" Valve Timing Springless .Valves Four Valves
per Cylinder 233-286

Contents 13

CHAPTER IX

PACES

Constructional Details of Pistons Aluminum Cylinders and Pistons
Piston Eing Construction Leak Proof Piston Eings Keeping Oil
Out of Combustion Chamber Connecting Eod Forms Connecting
Eods for Vee Engines Cam-Shaft and Crank-Shaft Designs Ball
Bearing Crank-Shafts Engine Base Construction .... 287-323

CHAPTER X

Power Plant Installation Curtiss OX-2 Engine Mounting and Operating
Eules Standard S. A. E. Engine Bed Dimensions Hall-Scott
Engine Installation and Operation- 1 Fuel System Eules Ignition
System Water System Preparations to Start Engine Mounting
Eadial and Eotary Engines Practical Hints to Locate Engine
Troubles All Engine Troubles Summarized Location of Engine
Troubles Made Easy 324-375

CHAPTER XI

Tools for Adjusting and Erecting Forms of Wrenches Use and Care
of Files Split Pin Eemoval and Installation Complete Chisel Set
Drilling Machines Drills, Eeamers, Taps and Dies Measuring
Tools Micrometer Calipers and Their Use Typical Tool Outfits
Special Hall-Scott Tools Overhauling Airplane Engines Taking
Engine Down Defects in Cylinders Carbon Deposits, Cause and
Prevention Use of Carbon Scrapers Burning Out Carbon with
Oxygen Eepairing Scored Cylinders^ Valve Eemoval and Inspec-
tion Eeseating and Truing Valves Valve Grinding Processes
Depreciation in Valve Operating System Piston Troubles Piston
Eing Manipulation Fitting Piston Eings Wrist-Pin Wear In-
spection and Eefitting of Engine Bearings Scraping Brasses to Fit
Fitting Connecting Eods Testing for Bearing Parallelism Cam-
Shafts and Timing Gears Precautions in Eeassembling Parts . 376-456

CHAPTER XII

Aviation Engine Types Division in Classes Anzani Engines Canton
and Unne Engine Construction of Gnome Engines "Monosou-
pape ' ' Gnome German f ' Gnome ' ' Type Le' Ehone Engine
Eenault Air-Cooled Engine Simplex Model "A" Hispano-Suiza
Curtiss Aviation Motors Thomas-Morse Model 88 Engine Duesen-
berg Engine Aeromarine Six-Cylinder Wisconsin Aviation
Engines Hall-Scott Engines Mercedes Motor Benz Motor
Austro-Daimler Engine Sunbeam-Coatalen Indicating and Meas-
uring Instruments Air Starting Systems Electric Starting Bat-
tery Ignition 457-571

INDEX . 573

AVIATION ENGINES

DESIGN CONSTRUCTION REPAIR

CHAPTER I

Brief Consideration of Aircraft Types Essential Requirements of
Aerial Motors Aviation Engines Must Be Light Factors In-
fluencing Power Needed Why Explosive Motors Are. Best His-
torical Main Types of Internal Combustion Engines.

BRIEF CONSIDERATION OF AIRCRAFT TYPES

THE conquest of the air is one of the most stupendous
achievements of the ages. Human flight opens the sky
to man as a new road, and because it is a road free of all
obstructions and leads everywhere, affording the shortest
distance to any place, it offers to man the prospect of
unlimited freedom. The aircraft promises to span con-
tinents like railroads, to bridge seas like ships, to go over
mountains and forests like birds, and to quicken and
simplify the problems of transportation. While the actual
conquest of the air is an accomplishment just being real-
ized in our days, the idea and yearning to conquer the air
are old, possibly as old as intellect itself. The myths of
different races tell of winged gods and flying men, and
show that for ages to fly was the highest conception of
the sublime. No other agent is more responsible for sus-
tained flight than the internal combustion motor, and it
was only when this form of prime mover had been fully
developed that it was possible for man to leave the ground
and alight at will, not depending upon the caprices of
the winds or lifting power of gases as with the balloon.
It is safe to say that the solution of the problem of flight
would have been attained many years ago if the proper
source of power had been available as all the essential

18 Aviation Engines

elements of the modern aeroplane and dirigible balloon,
other than the power plant, were known to early philoso-
phers and scientists.

Aeronautics is divided into two fundamentally differ-
ent branches aviatics and aerostatics. The first com-
prises all types of aeroplanes and heavier than air flying
machines such as the helicopters, kites, etc. ; the second
includes dirigible balloons, passive balloons and all craft
which rise in the air by utilizing the lifting force of gases.
Aeroplanes are the only practical form of heavier-than-air
machines, as the helicopters (machines intended to be
lifted directly into the air by propellers, without the sus-
taining effect of planes), and ornithopters, or flapping
wing types, have not been thoroughly developed, and in
fact, there are so many serious mechanical problems to
be solved before either of these types of air ' craft will
function properly that experts express grave doubts re-
garding the practicability of either. Aeroplanes are di-
vided into two main types monoplanes or single surface
forms, and bi-planes or machines having two sets of lift-
ing surfaces, one suspended over the other. A third type,
. the triplane, is not very widely used.

Dirigible balloons are divided into three classes: the
rigid, the semi-rigid, and the non-rigid. The rigid has a
frame or skeleton of either wood or metal inside of the
bag, to stiffen it; the semi-rigid is reinforced by a wire
net and metal attachments; while the non-rigid is just a
bag filled with gas. The aeroplane, more than the dirigible
and balloon, stands as the emblem of the conquest of the
air. Two reasons for this are that power flight is a real
conquest of the air, a real victory over the battling ele-
ments ; secondly, because the aeroplane, or any flying ma-
chine that may follow, brings air travel within the reach
of everybody. In practical development, the dirigible may
be the steamship of the air, which will render invaluable
services of a certain kind, and the aeroplane will be the
automobile of the air, to be used by the multitude, perhaps
for as many purposes as the automobile is now being used.

Aviation Motor Requirements 19

ESSENTIAL REQUIREMENTS OF AERIAL MOTORS

One of the marked features of aircraft development has
been the effect it has had upon the refinement and perfec-
tion of the internal combustion motor. Without question
gasoline-motors intended for aircraft are the nearest to
perfection of any other type yet evolved. Because of the
peculiar demands imposed upon the aeronautical motor it
must possess all the features of reliability, economy and
efficiency now present with automobile or marine engines
and then must have distinctive points of its own. Owing
to the unstable nature of the medium through which it is
operated and the fact that heavier-than-air machines can
maintain flight only as long as the power plant is func-
tioning properly, an airship motor must be more reliable
than any used on either land or water. While a few
pounds of metal more or less makes practically no dif-
ference in a marine motor and has very little effect upon
the speed or hill-climbing ability. of an automobile, an
airship motor must be as light as it is possible to make
it because every pound counts, whether the motor is to be
fitted into an aeroplane or in a dirigible balloon.

Airship motors, as a rule, must operate constantly at
high speeds in order to obtain a maximum power delivery
with a minimum piston displacement. In automobiles, or
motor boats, motors are not required to run constantly at
their maximum speed. Most aircraft motors must func-
tion for extended periods at speed as nearly the maximum
as possible. Another thing that militates against the air-
craft motor is the more or less unsteady foundation to
which it is attached. The necessarily light framework of the
aeroplane makes it hard for a motor to perform at maxi-
mum efficiency on account of the vibration of its foundation
while the craft is in flight. Marine and motor car engines,
while not placed on foundations as firm as those provided
for stationary power plants, are installed on bases of much
more stability than the light structure of an aeroplane.
The aircraft motor, therefore, must be balanced to a nicety

20 Aviation Engines

and must run steadily under the most unfavorable con-
ditions.

AERIAL MOTORS MUST BE LIGHT

The capacity of light motors designed for aerial work
per unit of mass is surprising to those not fully con-
versant with the possibilities that a thorough knowledge
of proportions of parts and the use of special metals
developed by the automobile industry make possible. Ac-
tivity in the development of light motors has been more
pronounced in France than in any other country. Some
of these motors have been complicated types made light
by the skillful proportioning of parts, others are of the
refined simpler form modified from current automobile
practice. There is a tendency to depart from the freakish
or unconventional construction and to adhere more closely
to standard forms because it is necessary to have the parts
of such size that every quality making for reliability,
efficiency and endurance are incorporated in the design.
Aeroplane motors range from two cylinders to forms hav-
ing fourteen and sixteen cylinders and the arrangement
of these members varies from the conventional vertical
tandem and opposed placing to the V form or the more
unusual radial motors having either fixed ^ or rotary cyl-
inders. The weight has been reduced so ft* is possible to
obtain a complete power plant of the revolving cylinder
air-cooled type that will not weigh more than three pounds
per actual horse-power and in some cases less than this.

If we give brief consideration to the requirements of
the aviator it will be evident that one of the most im-
portant is securing maximum power with minimum mass,
and it is desirable to conserve all of the good qualities
existing in standard automobile motors. These are cer-
tainty of operation, good mechanical balance and uniform
delivery of power fundamental conditions which must be
attained before a power plant can be considered practical.
There are in addition, secondary considerations, none the
less desirable, if not absolutely essential. These are min-

Factors Influencing Power Needed 21

imum consumption of fuel and lubricating oil, which is
really a factor of import, for upon the economy depends
the capacity and flying radius. As the amount of liquid
fuel must be limited the most suitable motor will be that
which is powerful and at the same time economical. An-
other important feature is to secure accessibility of com-
ponents in order to make easy repair or adjustment of
parts possible. It is possible to obtain sufficiently light-
weight motors without radical departure from established
practice. Water-cooled power plants have been designed
that will w T eigh but four or five pounds per horse-power
and in these forms we have a practical power plant
capable of extended operation.

FACTORS INFLUENCING POWER NEEDED

Work is performed whenever an object is moved against
a resistance, and the amount of work performed depends
not only on the amount of resistance overcome but also
upon the amount of time utilized in accomplishing a given
task. Work is measured in horse-power for convenience.
It will take one horse-power to move 33,000 pounds one
foot in one minute or 550 pounds one foot in one second.
The same work would be done if 330 pounds were moved
100 feet in one ^ minute. It requires a definite amount of
power to move a vehicle over the ground at a certain
speed, so it must take power to overcome resistance of
an airplane in the air. Disregarding the factor of air
density, it will take more power as the speed increases
if the weight or resistance remains constant, or more
power if the speed remains constant and the resistance
increases. The airplane is supported by air reaction un-
der the planes or lifting surfaces and the value of this
reaction depends upon the shape of the aerofoil, the
amount it is tilted and the speed at which it is drawn
through the air. The angle of incidence or degree of
wing tilt regulates the power required to a certain degree
as this affects the speed of horizontal flight as well as the
resistance. Eesistance may be of two kinds, one that is

22 Aviation Engines

necessary and the other that it is desirable to reduce to
the lowest point possible. There is the wing resistance
and the sum of the resistances of the rest of the machine
such as fuselage, struts, wires, landing gear, etc. If we
assume that a certain airplane offered a total resistance
of 300 pounds and we wished to drive it through the air
at a speed of sixty miles per hour, we can find the horse-
power needed by a very simple computation as follows :
The product of

300 pounds resistance times speed of 88 feet
per second times 60 seconds in a minute

- = H.P. needed,
divided by 33,000 foot pounds per minute

in one horse-power

The result is the horse-power needed, or

300 X 88 X 60

= 48 H.P.

33,000

Just as it takes more power to climb a hill than it does
to run a car on the level, it takes more power to climb
in the air with an airplane than it does to fly on the level.
The more rapid the climb, the more power it will take.
If the resistance remains 300 pounds and it is necessary
to drive the plane at 90 miles per hour, we merely sub-
stitute proper values in the above formula and we have

300 pounds times 132 feet per second times 60
seconds in a minute

rrc\ TT T>

33,000 foot pounds per minute in one
horse-power

The same results can be obtained by dividing the product
of the resistance in pounds times speed in feet per second
by 550, which is the foot-pounds of work done in one
second to equal one horse-power. Naturally, the amount
of propeller thrust measured in pounds necessary to drive
an airplane must be greater than the resistance by a sub-
stantial margin if the plane is to fly and climb as well.

Computations for Horse-Power Needed

The following formulae were given in "The Aeroplane"
of London and can be used to advantage by those desiring
to make computations to ascertain power requirements:
The thrust of the propeller depends on the power of

L= Lift = Weighl = W

D = Drift

R= Reaction

Angle of Incidence

Pr- Momentum- M

Pr 2 Jt = Work

Pr 2 31= WorkMln.

'.P. or in English
Pr27CR

33.000

-H.P.

2rJt

Fig. 1. Diagrams Illustrating Computations for Horse-Power Required for

Airplane Flight.

24 Aviation Engines

the motor, and on the diameter and pitch of the propeller.
If the required thrust to a certain machine is known, the
calculation for the horse-power of the motor should be an
easy matter.

The required thrust is the sum of three different " re-
sistances. " The first is the ' 'drift " (dynamical head re-
sistance of the aerofoils), i.e., tan a x lift (L), lift being
equal to the total weight of machine (W) for horizontal
flight and equal to the angle of incidence. Certainly we
must take the tan a at the maximum K v value for minimum
speed, as then the drift is the greatest (Fig. 1, A).

Another method for finding the drift is D K X AV 2 ,
when we take the drift again so as to be greatest.

The second " resistance " is the total head resistance
of the machine, at its maximum velocity. And the third
is the thrust for climbing. The horse-power for climbing
can be found out in two different ways. I first propose
to deal with the method, where we find out the actual
horse-power wanted for a certain climbing speed to our
machine, where

climbing speed/sec. X W

H.P. =

550

In this case we know already the horse-power for climb-
ing, and we can proceed with our calculation.

With the other method we shall find out the "thrust"
in pounds or kilograms wanted for climbing and add it
to drift and total head resistance, and we shall have the
total " thrust " of our machine and we shall denote it
with T, while thrust for climbing shall be T c .

The following calculation is at our service to find out

VcXW

this thrust for climbing H.P.,

550

H.P. X 550

thence Vc = (1)

Computations for Horse-Power Needed 25

To XV

H.P. = - - , then from
550

To XV
- X550

550 To XV VcXW

(1) Vc = - = - - , thence, T c = -
W W V

Whether T means drifts, head resistance and thrust
for climbing, or drift and head resistance only, the fol-
lowing calculation is the same, only in the latter case, of
course, we must add the horse-power required for climb-
ing to the result to obtain the total horse-power.

Now, when we know the total thrust, we shall find the
horse-power in the following manner:

Pr2*R

We know that the H.P. = - in kilograms, or in

75X60

English measure, H.P. = - (Fig. 1, B)

33,000

where P = pressure in klgs. or Ibs.

r = radius on which P is acting.
R = Revolution/min.

M.R. 2 w

When B X r = M, then H.P. = - , thence,

4,500

H.P. X 4,500 716.2 H.P.

M = - - = - - in meter kilograms,
R2* R

H.P. 33,000 5253.1 H.P.
or in English system M = - in foot

R2* R

pounds.

Now the power on the circumference of the propeller

M
will be reduced by its radius, so it will be p. A part

26 Aviation Engines

of p will be used for counteracting the air and bearing fric-
tion, so that the total power on the circumference of the

propeller will be X *) = P where rj is the mechanical
r

fi
efficiency of the propeller. Now - - = T, where a is taken

tan <x

on the tip of the propeller.

I take a at the tip, but it can be taken, of course, at any

point, but then in equation p = , r must be taken only up

to this point, and not the whole radius ; but it is more corn-

Pitch
fortable to take it at the tip, as tan a = - (Fig. 1, C).

r2?u

Now we can write up the equation of the thrust :

716.2 H.P. rj 5253.1 H.P. YJ

T = - - , or in English measure

R r tan a R r tan a

T X R X r tan a

thence H.P. = - , or in English measure
716.2 r]

T X R X r tan a

5253.1 r]

The computations and formulae given are of most value
to the student engineer rather than matters of general
interest, but are given so that a general idea may be
secured of how airplane design influences power needed
to secure sustained flight. It will be apparent that the
resistance of an airplane depends upon numerous con-
siderations of design which require considerable research
in aerodynamics to determine accurately. It is obvious
that the more resistance there is, the more power needed
to fly at a given speed. Light monoplanes have been
flown with as little as 15 horse-power for short distances,

Why Explosive Motors Are Best 27

but most planes now built use engines of 100 horse-power
or more. Giant airplanes have been constructed having
2,000 horse-power distributed in four power units. The
amount of power provided for an airplane of given design
varies widely as many conditions govern this, but it will
range from approximately one horse-power to each 8
pounds weight in the case of very light, fast machines
to one horse-power to 15 or 18 pounds of the total weight
in the case of medium speed machines. The development
in airplane and power plant design is so rapid, however,
that the figures given can be considered only in the light
of general averages rather than being typical of current
practice.

WHY EXPLOSIVE MOTOKS ARE BEST

Internal combustion engines are best for airplanes "and
all types of aircraft for the same reasons that they are
universally used as a source of power for automobiles.
The gasoline engine is the lightest known form of prime
mover and a more efficient one than a steam engine, es-
pecially in the small powers used for airplane propul-
sion. It has been stated that by very careful designing
a steam plant and engine could be made that would be
practical for airplane propulsion, but even with the latest
development it is doubtful if steam power can be utilized
in aircraft to as good advantage as modern gasoline-
engines are. While the steam-engine is considered very
much simpler than a gas-motor, the latter is much more
easily mastered by the non-technical aviator and certainly
requires less attention. A weight of 10 pounds per horse-
power is possible in a condensing steam plant but this
figure is nearly double or triple what is easily secured
with a gas-motor which may weigh but 5 pounds per horse-
power in the water cooled forms and but 2 or 3 pounds
in the air-cooled types. The fuel consumption is twice
as great in a -steam-power plant (owing to heat losses)
as would be the case in a gasoline engine of equal power
and much IP.SS weight.

28 Aviation Engines

The internal-combustion engine has come seemingly
like an avalanche of a decade; but it has come to stay,
to take its well-deserved position among the powers for
aiding labor. Its ready adaptation to road, aerial and
marine service has made it a wonder of the age in the
development of speed not before dreamed of as a possi-
bility; yet in so short a time, its power for speed has
taken rank on the common road against the locomotive
on the rail with its century's progress. It has made aerial
navigation possible and practical, it furnishes power for
all marine craft from the light canoe to. the transatlantic
liner. It operates the machine tools of the mechanic, tills
the soil for the farmer and provides healthful recreation
for thousands by furnishing an economical means of trans-
port by land and sea. It has been a universal mechanical
education for the masses, and in its present forms repre-
sents the great refinement and development made possible
by the concentration of the world's master minds on the
problems incidental to internal combustion engineering.

HISTOKICAL

Although the ideal principle of explosive power was
conceived some two hundred years ago, at which time
--experiments' were made with gunpowder as the explosive
element, it was not until the last years of the eighteenth
century that the idea took a patentable shape, and not
until about 1826 (Brown's gas- vacuum engine) that a fur-
ther progress was made in England by condensing the
products of combustion by a jet of water, thus creating
a partial vacuum.

Brown's was probably the first explosive engine that
did real work. It was clumsy and unwieldy and was soon
relegated to its place among the failures of previous ex-
periments. No approach to active explosive effect in a
cylinder was reached in practice, although many ingenious
designs were described, until about 1838 and the following
years. Barnett's engine in England was the first attempt
to compress the charge before exploding. From this ^Ime

Why Explosive Motors Are Best 29

on to about 1860 many patents were issued in Europe and
a few in the United States for gas-engines, but the prog-
ress was .slow, and its practical introduction for power
came with spasmodic effect and low efficiency. From 1860
on, practical improvement seems to have been made, and
the Lenoir motor was produced in France and brought
to the United States. It failed to meet expectations, and
was soon followed by further improvements in the Hugon
motor in France (1862), followed by Beau de Rocha's
four-cycle idea, which has been slowly developed through
a long series of experimental trials by different inventors.
In the hands of Otto and Langdon a further progress was
made, and numerous patents were issued in England,
France, and Germany, and followed up by an increasing
interest in the United States, with a few patents.

From 1870 improvements seem to have advanced at
a steady rate, and largely in the valve-gear and precision
of governing for variable load. The early idea of the ne-
cessity of slow combustion was a great drawback in the
advancement of efficiency, and the suggestion of de Eocha
in 1862 did not take root as a prophetic truth until many
failures and years of experience had taught the funda-
mental axiom that rapidity of action in both combustion
and expansion was the basis of success in explosive motors.

With this truth and the demand for small and safe
prime movers, the manufacture of gas-engines increased
in Europe and America at a more rapid rate, and improve-
ments in perfecting the details of this cheap and efficient
prime mover have finally raised it to the dignity of a
standard motor and a dangerous rival of the steam-engine
for small and intermediate powers, with a prospect of
largely increasing its individual units to many hundred,
if not to the thousand horse-power in a single cylinder.
The unit size in a single cylinder has now reached to about
700 horse-power and by combining cylinders in the same
machine, powers of from 1,500 to 2,000 horse-power are
now available for large power-plants.

30 Aviation Engines

MAIN TYPES OF INTERNAL-COMBUSTION ENGINES

This form of prime mover has been built in so many
different types, all of which have operated with some
degree of success that the diversity in form will not be
generally appreciated unless some attempt is made to
classify the various designs that have received practical
application. Obviously the same type of engine is not
universally applicable, because each class of work has
individual peculiarities which can best be met by an en-
gine designed with the peculiar conditions present in view.
The following tabular synopsis will enable the reader to
judge the extent of the development of what is now the
most popular prime mover for all purposes.

A. Internal Combustion (Standard Type)

1. Single Acting (Standard Type)

2. Double Acting (For Large Power Only)
, 3. Simple (Universal Form)

4. Compound (Barely Used)

5. Eeciprocating Piston (Standard Type)

6. Turbine (Revolving Eotor, not fully devel-

oped)

Al. Two-Stroke Cycle

a. Two Port

b. Three Port

c. Combined Two and Three Port

d. Fourth Port Accelerator

e. Differential Piston Type

f. Distributor Valve System

A2. Four-Stroke Cycle

a. Automatic Inlet Valve

b. Mechanical Inlet Valve

c. Poppet or Mushroom Valve

d. Slide Valve

d 1. Sleeve Valve

d 2. Eeciprocating Eing Valve

d 3. Piston Valve

Gas Engine Types Classified 31

e. Eotary Valves

e 1. Disc

e 2. Cylinder or Barrel

e 3. Single Cone

e 4. Double Cone

f. Two Piston (Balanced Explosion)

g. Eotary. Cylinder, Fixed Crank (Aerial)

h. Fixed Cylinder, Eotary Crank (Standard
Type)

A3. Six-Stroke Cycle

B. External Combustion (Practically Obsolete)

a. Turbine, Eevolving Eotor

b. Eeciprocating Piston

CLASSIFICATION BY CYLINDER ARRANGEMENT

Single Cylinder

a. Vertical

b. Horizontal

c. Inverted Vertical

Double Cylinder

a. Vertical

b. Horizontal (Side by Side)

c. Horizontal (Opposed)

d. 45 to 90 Degrees V (Angularly Disposed)

e. Horizontal Tandem (Double Acting)

Three Cylinder

a. Vertical

b. Horizontal

c. Eotary (Cylinders Spaced at 120 Degrees)

d. Eadially Placed (Stationary Cylinders)

e. One Vertical, One Each Side at an Angle

f. Compound (Two High Pressure, One Low

Pressure)

Four Cylinder

a. Vertical

b. Horizontal (Side by Side)

32 Aviation Engines

c. Horizontal (Two Pairs Opposed)

d. 45 to 90 Degrees V

e. Twin Tandem (Double Acting)

Five Cylinder

a. Vertical (Five Throw Crankshaft)

b. Eadially Spaced at 72 Degrees (Stationary)

c. Eadially Placed Above Crankshaft ( Station-

ary)

d. Placed Around Rotary Crankcase (72 Degrees

Spacing)

Six Cylinder

a. Vertical

b. Horizontal (Three Pairs Opposed)

c. 45 to 90 Degrees V

Seven Cylinder

a. Equally Spaced (Eotary)

Eight Cylinder

a. Vertical

b. Horizontal (Four Pairs Opposed)

c. 45 to 90 Degrees V

Nine Cylinder
. a. Equally Spaced (Eotary)

Twelve Cylinder

a. Vertical

b. Horizontal (Six Pairs Opposed)

c. 45 to 90 Degrees V

Fourteen Cylinder
a. Eotary

Sixteen Cylinder

a. 45 to 90 Degrees V

b. Horizontal (Eight Pairs Opposed)

Eighteen Cylinder
a. Eotary Cylinder

Two- Cylinder, Double Acting/Four Cycle Engine for Blast Furnace Gas Fuel

Weight 600 Pounds per Horsepower
Very slow speed, made in siz.es uptb 2000 Horsepower. 60io 100 R.P.M.

Two Cylinder Opposed Gas Engine - 150 to 650 Horsepower Sizes.
500 to 600 Pounds per Horsepower. 90 to 100 R.P.M.

Stationary Diesel Engine s d Stationary Gas Engine
450 to 500 Pounds per Approximately Four Cycle -Two Cylinder
Horsepower 200 R.P.M. 500 Pounds per Horsepower

Fig. 2. Plate Showing Heavy, Slow Speed Internal Combustion Engines
Used Only for Stationary Power in Large Installations Giving Weight
to Horse-Power Ratio.

Four Cylinder Diesel Engine for Marine Use
250 Pounds perHorsepower

Two- Cycle Marine Engine
50-100 Pounds per Horsepower
600to 800 R.P M.

Single Cylinder Vertical Farm Engine
150 Pounds per Horsepower- Speed 400 R RM.

Two Cylinder Four Cycle Tractor Engine
15 Pounds per Horsepower
800 to 1000. R.P.M .

Four -Cylinder Four Cycle Automobile PowerPlant:
Weiqhsabout ZS Pounds per Horsepower
IZOO to ZOOO R.P. M.

Pig. 3. Various Forms of Internal Combustion Engines Showing Decrease

in Weight to Horse-Power Ratio with Augmenting Speed of Rotation.

34 ,

Eight Cylmder"Vee"Au+onnobile Engine
15 to 18 Pounds per Horse power
Speeds 1500 toZOOOR P.M.

Two Cylinder-AirCooled Motorcycle

Engine weighH 8MO Pounds Horsepower

Speed 3000 R. P.M.

Six, Eight or Twelve Cylinder Water Cooled Aviation Engine, Tandem or V Form

4 to 6 Pounds per Horsepower
Speed 1500 R,R M. Direct Coupled - 2000 R RM.Geared'Drive

Seven or Nine Cylinder Revolving

Air Cooled
Speed 1200 R.RM.2.8Pounds perHorsepowsr

Fourteen or Eighteen Cylinder
Revolving Air Cooled Aviation Engine

. Speed 1200 R.P.M.
2 Pounds per Horsepower

Fig. 4. Internal Combustion Engine Types of Extremely Fine Construction
and Kefined Design, Showing Great Power Outputs for Very Small
Weighty a Feature Very Much Desired in Airplane Power Plants.

#6 Aviation Engines

Of all the types enumerated above engines having less
than eight cylinders are the most popular in everything
but aircraft work. The four-cylinder vertical is without
doubt the most widely used of all types owing to the
large number employed as automobile power plants.
Stationary engines in small and medium powers are in-
variably of the single or double form. Three-cylinder
engines are seldom, used at the present time, except in
marine work and in some stationary forms. Eight- and
twelve-cylinder motors have received but limited appli-
cation and practically always in automobiles, racing motor
boats or in aircraft.' The only example of a fourteen-
cylinder motor to be used to any extent is incorporated
in aeroplane construction. This is also true of the six-
teen- and eighteen-cylinder forms and of twenty-four-
cylinder engines now in process of development.

The duty an engine is designed for determines the
weight per horse-power. High powered engines intended
for steady service are always of the slow speed type and
consequently are of very massive construction. Various
forms of heavy duty type stationary engines are shown
at Fig. 2. Some of these engines may weigh as much as
600 pounds per horse-power. A further study is possible
by consulting data given on Figs. 3 and 4. As the crank-
shaft speed increases and cylinders are multiplied the
engines become lighter. While the big stationary power
plants may run for years without attention, airplane en-
gines require rebuilding after about 60 to 80 hours air
service for the fixed cylinder types and 40 hours or less
for the rotary cylinder air-cooled forms. There is evi-
dently a decrease in durability and reliability as the
weight is lessened. These illustrations also permit of
obtaining a good idea of the variety of forms internal
combustion engines are made in.

CHAPTER II

OPERATING PRINCIPLES OF TWO- AND FOUR-STROKE
CYCLE ENGINES

BEFORE discussing the construction of the various forms
of internal combustion engines it may be well to describe
the operating cycle of the types most generally used.
The two-cycle engine is the simplest because there are no
valves in connection with the cylinder, as the gas is in-
troduced into that member and expelled from it through
ports cored into the cylinder walls. These are covered by
the piston at a certain portion of its travel and uncov-
ered at other parts of its stroke. In the four-cycle engine
the explosive gas is admitted to the cylinder through a
port at the head end closed by a valve, while the exhaust
gas is expelled through another port controlled in a simi-
lar manner. These valves are operated by mechanism
distinct from the piston.

The action of the four-cycle type may be easily under-
stood if one refers to illustrations at Figs. 5 and 6. It
is called the "four-stroke engine" because the piston must
make four strokes in the cylinder for each explosion or
power impulse obtained. The principle of the gas-engine
of the internal combustion type is similar to that of a
gun, i.e., power is obtained by the rapid combustion of
some explosive or other quick burning substance. The
bullet is driven out of the gun barrel by the pressure of
the gas evolved when the charge of powder is ignited.
The piston or movable element of the gas-engine is driven,

Aviation Engines

from the closed or head end to the crank end of the
cylinder by a similar expansion of gases resulting from
combustion. The first operation in firing a gun or secur-
ing an explosion in the cylinder of the gas-engine is to

7. Cylinder Filling with Gas,

2, Piston Compressing Gas.

Inlet Pipe

Inlet Value
shown Ope,

Exhaust Valv
Closed

Exhaust Pipe
Vo/t/.e Spring

Cam

Camshaft

Cylinder Filled with
' Combustible Gas

Cooling Flanges

Piston Ascending

Lower Half
Cranhcase

'amrod

/. Powder Inserted.

2. Powder Compressed.

Fig. 5. Outlining First Two Strokes of Piston in Four-Cycle Engine.

fill the combustion space with combustible material. This
is done by a down stroke of the piston during which time
the inlet valve opens to admit the gaseous charge to the
cylinder interior. This operation is shown at Fig. 5, A.
The second operation is to compress this gas which is
done by an upward stroke of the piston as shown at Fig,

Internal Combustion Engine Action

5, B. When the top of the compression stroke is reached,
the gas is ignited and the piston is driven down toward
the open end of the cylinder, as indicated at Fig. 6, C The
fourth operation or exhaust stroke is performed by the

8. Compressed Gas Exploded.

4. Inert Gases Exhausted,

Bath Values Closed

Spark Plug
Cooling Flanges

serf Oas
~ Being Ignited
3 by Spark.

3. Powder Exploded.

4. Powder Gas Exhausted.

Fig. 6. Outlining Second Two Strokes of Piston in Four-Cycle Engine.

return upward movement of the piston as shown at Fig.
6, D during which time the exhaust valve is opened to
permit the burnt gases to leave the cylinder. As soon
as the piston reaches the top of its exhaust stroke, the
energy stored in the fly-wheel rim during the power stroke
causes that member to continue revolving and as the piston

Aviation Engines

Spark Plug ._

Gas Flowing ;n-. s

Piston Goes
Down

Connecting
Rod

.A- Intake Stroke
Water Space

Gas ai
High Press u re -

Piston

Goes Down-. "'

Cylinder -

C- Power Stroke

D- Exhaust Stroke

Fig. 7. Sectional View of L Head Gasoline Engine Cylinder Showing
Piston Movements During Four-Stroke Cycle.

How Two-Stroke Cycle Engine Works 41

again travels on its down stroke the inlet valve opens and
admits a charge of fresh gas and the cycle of operations
is repeated.

The illustrations at Fig. 7 show how the various cycle
functions take place in an L head type water cooled cyl-
inder engine. The sections at A and C are taken through
the inlet valve, those at B and D are taken through the
exhaust valve.

The two-cycle engine works on a different principle, as
while only the combustion chamber end of the piston is
employed to do useful work in the four-cycle engine, both
upper and lower portions are called upon to perform the
functions necessary to two-cycle engine operation. In-
stead of the gas being admitted into the cylinder as is the
case with the four-stroke engine, it is first drawn into the
engine base where it receives a preliminary compression
prior to its transfer to the working end of the cylinder.
The views at Fig. 8 should indicate clearly the operation
of the two-port two-cycle engine. At A the piston is
seen reaching the top of its stroke and the gas above the
piston is being compressed ready for ignition, while the
suction in the engine base causes the automatic valve to
open and admits mixture from the carburetor to the
crank case. When the piston reaches the top of its stroke,
the compressed gas is ignited and the piston is driven
down on the power stroke, compressing the gas in the
engine base.

When the top of the piston uncovers the exhaust port
the flaming gas escapes because of its pressure. A down-
ward movement of the piston uncovers the inlet port
opposite the exhaust and permits the fresh gas to bypass
through the transfer passage from the engine base to the
cylinder. The conditions with the intake and exhaust
port fully opened are clearly shown at Fig. 8, C. The
deflector plate on the top of the piston directs the enter-
ing fresh gas to the top of the cylinder and prevents the
main portion of the gas stream from flowing out through
the open exhaust port. On the next upstroke of the piston

Aviation Engines

How Two-Stroke Cycle Engine Works

fao

44 Aviation Engines

the gas in the cylinder is compressed and the inlet valve
opened, as shown at A to permit a fresh charge to enter
the engine base.

The operating principle of the three-port, two-cycle
engine is practically the same as that previously described
with the exception that the gas is admitted to the crank-
case through a third port in the cylinder wall, which is
uncovered by the piston when that member reaches the
end of its upstroke. The action of the three-port form
can be readily ascertained by studying the diagrams given
at Fig. 9. Combination two- and three-port engines have
been evolved and other modifications made to improve the
action.

THE TWO-CYCLE AND FOUK-CYCLE TYPES

In the earlier years of explosive-motor progress was
evolved the two types of motors in regard to the cycles
of their operation. The early attempts to perfect the
two-cycle principle were for many years held in abeyance
from the pressure of interests in the four-cycle type, until
its simplicity and power possibilities were demonstrated
by Mr. Dugald Clerk in England, who gave the principles
of the two-cycle motor a broad bearing leading to im-
mediate improvements in design, which has made further
progress in the United States, until at the present time
it has an equal standard value as a motor-power in some
applications as its ancient rival the four-cycle or Otto
type, as demonstrated by Beau de Eocha in 1862.

Thermodynamically, the methods of the two types are
equal as far as combustion is concerned, and compression
may favor in a small degree the four-cycle type as well
as the purity of the charge. The cylinder volume of the
two-cycle motor is much smaller per unit of power, and
the enveloping cylinder surface is therefore greater per
unit of volume. Hence more heat is carried off by the
jacket water during compression, and the higher com-
pression available from this tends to increase the economy
during compression which is lost during expansion.

Two- and Four-Stroke Cycles Compared 45

From the above considerations it may be safely stated
that a lower temperature and higher pressure of charge
at the beginning of compression is obtained in the two-
cycle motor, greater weight of charge and greater specific
power of higher compression resulting in higher thermal
efficiency. The smaller cylinder for the same power of
the two-cycle motor gives less friction surface per impulse
than of the other type; although the crank-chamber pres-
sure may, in a measure, balance the friction of the four-
cycle type. Probably the strongest points in favor of the
two-cycle type are the lighter fly-wheel and the absence
of valves and valve gear, making this type the most simple
in construction and the lightest in weight for its developed
power. Yet, for the larger power units, the four-cycle
type will no doubt always maintain the standard for
efficiency and durability of action.

The distribution of the charge and its degree of mix-
ture with the remains of the previous explosion in the
clearance space, has been a matter of discussion for both
types of explosive motors, with doubtful results. In Fig.
10, A we illustrate what theory suggests as to the distribu-
tion of the fresh charge in a two-cycle motor, and in Fig.
10, B what is the probable distribution of the mixture when
the piston starts on its compressive stroke. The arrows
show the probable direction of flow of the fresh charge
and burnt gases at the crucial moment.

In Fig. 10, C is shown the complete out-sweep of the
products of combustion for the full extent of the piston
stroke of a four-cycle motor, leaving only the volume of
the clearance to mix with the new charge and at D the
manner by which the new charge sweeps by the ignition
device, keeping it cool and avoiding possibilities of pre-
ignition by undue heating of the terminals of the sparking
device. Thus; by enveloping the sparking device with
the pure mixture, ignition spreads through the charge with
its greatest possible velocity, a most desirable condition
in high-speed motors with side-valve chambers and igni-
ters within the valve chamber.

Aviation Engines

Theoretical condition.

Exhaust.

Practical condition.

New charge.

Pig. 10. Diagrams Contrasting Action of Two- and Four-Cycle Cylinders
on Exhaust and Intake Stroke.

Internal Combustion Engine Theory 47

THEORY OF THE GAS AND GASOLINE ENGINE

The laws controlling the elements that create a power
by their expansion by heat due to combustion, when prop-
erly understood, become a matter of - computation in
regard to their value as an agent for generating power
in the various kinds of explosive engines. The method
of heating the elements of power in explosive engines
greatly widens the limits of temperature as available in
other types of heat-engines. It disposes of many of the
practical troubles of hot-air, and even of steam-engines,
in the simplicity and directness of application of the ele-
ments of power. In the explosive engine the difficulty
of conveying heat for producing expansive effect by con-
vection is displaced by the generation of the required heat
within the expansive element and at the instant of its
useful work. The. low conductivity of heat to and from
air has been the great obstacle in the practical develop-
ment of the hot-air engine; while, on the contrary, it has
become the source of economy and practicability in the
development of the internal-combustion engine.

The action of air, gas, and the vapors of gasoline and
petroleum oil, whether singly or mixed, is affected by
changes of temperature practically in nearly the same
ratio; but when the elements that produce combustion are
interchanged in confined spaces, there is a marked differ-
ence of effect. The oxygen of the air, the hydrogen and
carbon of a gas, or vapor of gasoline or petroleum oil are
the elements that by combustion produce heat to expand
the nitrogen of the air and the watery vapor produced
by the union of the oxygen in the i air and the hydrogen in
the gas, as well as also the monoxide and carbonic-acid
gas that may be formed by the union of the carbon of
gas or vapor with part of the oxygen of the air. The
various mixtures as between air and gas, or air and vapor,
with the proportion of the products of combustion left
in the cylinder from a previous combustion, form the
elements to be considered in estimating the amount of

48 Aviation Engines

pressure that may be. obtained by their combustion and
expansive force.

EARLY GAS ENGINE FOKMS

The working' process of the explosive motor may be
divided into three principal types : 1. Motors with charges
igniting at constant volume without compression, such as
the Lenoir, Hugon, and other similar types now abandoned
as wasteful in fuel and effect. 2. Motors with charges
igniting at constant pressure with compression, in which
a receiver is charged by a pump and the gases burned
while being admitted to the motor cylinder, such as types
of the Simon and Brayton engine. 3. Motors with charges
igniting at constant volume with variable compression,
such as the later two- and four-cycle motors with compres-
sion of the indrawn charge; limited in the two-cycle type
and variable in the four-cycle type with the ratios of the
clearance space in the cylinder. This principle produces
the explosive motor of greatest efficiency.

The phenomena of the brilliant light and its accom-
panying heat at the moment of explosion .have been wit-
nessed in. the experiments of Dugald Clerk in England,
the illumination lasting throughout the stroke; but in
regard to time in a four-cycle engine, the incandescent
state exists only one-quarter of the running time. Thus
the time interval, together with the non-conductibility of
the gases, makes the phenomena o*f a high-temperature
combustion within the comparatively cool walls of a cyl-
inder a practical possibility.

THE ISOTHERMAL LAW

The natural laws, long since promulgated by Boyle,
Gay Lussac, and others, on the subject of the expansion
and compression of gases by force and by heat, and their
variable pressures and temperatures when confined, are
conceded to be practically true and applicable to all gases,
whether single, mixed, or combined.

Isothermal Law. 49

The law formulated by Boyle only relates to the com-
pression and expansion of gases without a change of
temperature, and is stated in these words:

// the temperature of a gas be kept constant, its pres-
sure or elastic force will vary inversely as the volume
it occupies.

It is expressed in the formula P X V - = C, or pressure

C C

X volume = constant. Hence, = V and = P.

P V

Thus the curve formed by increments of pressure dur-
ing the expansion or compression of a given volume of
gas without change of temperature is designated as the
isothermal curve in which the volume multiplied by the
pressure is. a constant value in expansion, and inversely
the pressure divided by the volume is a constant value
in compressing a gas.

But as compression and expansion of gases require
force for their accomplishment mechanically, or by the
application or abstraction of heat chemically, or by con-
vection, a second condition becomes involved, which was
formulated into a law of thermodynamics by Gay Lussac
under the following conditions: A given volume of gas
under a free piston expands by heat and contracts by the
loss of heat, its volume causing a proportional movement
of a free piston equal to ^73 part of the cylinder volume
for each degree Centigrade difference in temperature, or
%92 part of its volume for each degree Fahrenheit. "With
a fixed piston (constant volume), the pressure is increased
or decreased by an increase or decrease of heat in the
same proportion of %TS part of its pressure for each
degree Centigrade, or %92 part of its pressure for each
degree Fahrenheit change in temperature. This is the
natural sequence of the law of mechanical equivalent,
which is a necessary deduction from the principle that

50 Aviation Engines

nothing in nature can be lost or wasted, for all the heat
that is imparted to or abstracted from a gaseous body
must be accounted for, either as heat or its equivalent
transformed into some other form of energy. In the case
of a piston moving in a cylinder by the expansive force
of heat in a gaseous body, all the heat expended in ex-
pansion of the gas is turned into work; the balance must
be accounted for in absorption by the cylinder or radiation.

THE ADIABATIC LAW

This theory is equally applicable to the cooling of gases
by abstraction of heat or by cooling due to expansion by
the motion of a piston. The denominators of these heat
fractions of expansion or contraction represent the ab-
solute zero of cold below the freezing-point of water, and
read 273 C. or 492.66 = 460.66 F. below zero:
and these are the starting-points of reference in com-
puting the. heat expansion in gas-engines. According to
Boyle's law, called the first law of gases, there are but
two characteristics of a gas and their variations to be
considered, viz., volume and pressure: while by the law
of Gay Lussac, called the second law of gases, a third
is added, consisting of the value of the absolute tem-
perature, counting from absolute zero to the temperatures
at which the operations take place. This is the Adiabatic
law.

The ratio of the variation of the three conditions
volume, pressure, and heat from the absolute zero tem-
perature has a certain rate, in which the volume multi-
plied by the pressure and the product divided by the
absolute temperature equals the ratio of expansion for
each degree. ' If a volume of air is contained in a cylinder
having a piston and fitted with an indicator, the piston,
if moved to and fro slowly, will alternately compress and
expand the air, and the indicator pencil will trace a line
or lines upon the card, which lines register the change
of pressure and volume occurring in the cylinder. If the
piston is perfectly free from leakage, and it be supposed

Adiabatic Law

that the temperature of the air is kept quite constant,
then the line so traced is called an Isothermal line, and
the pressure at any point when multiplied by the volume
is a constant, according to Boyle's law,

pv = a constant.

If, however, the piston is moved very rapidly, the air will
not remain at constant temperature, but the temperature
will increase because work has been done upon the air,

W 30

17 J

V-"-

0.5

40
30

^~~-

=^_

===

ATMOSPHERIC

LINES

10 20 30 40 50 60 70 80 90 100

VOLUME

Fig. 11. Diagram Isothermal and Adiabatic Lines.

and the heat has no time to escape by conduction. If no
heat whatever is lost by any cause, the line will be traced
over and over again by the indicator pencil, the cooling
by expansion doing work precisely equalling the heating
by compression. This is the line of no transmission of
heat, therefore known as Adiabatic.

The expansion of a gas % 7 3 of its volume for every
degree Centigrade, added to its temperature, is equal to
the decimal .00366, the coefficient of expansion for Centi-
grade units. To any given volume of a gas, its expansion
may be computed by multiplying the coefficient by the

52 Aviation Engines

number of degrees, and by reversing the process the degree
of acquired heat may be obtained approximately. These
methods are not strictly in conformity with the absolute
mathematical formula, because there is a small increase
in the increment of expansion of a dry gas, and there is
also a slight difference in the increment of expansion due
to moisture in the atmosphere and to the vapor of water
formed by the union of the hydrogen and oxygen in the
combustion chamber of explosive engines.

TEMPERATURE COMPUTATIONS

The ratio of expansion on the Fahrenheit scale is de-
rived from the absolute temperature below the freezing-
point of water (32) to correspond with the Centigrade

scale ; therefore - = .0020297, the ratio of expansion

492.66

from 32 for each degree rise in temperature on the Fah-
renheit scale. As an example, if the temperature of any
volume of air or gas at constant volume is raised, say
from 60 to 2000 F., the increase in temperature will be

1940. The ratio will be = .0019206. Then by the

520.66

formula :

Eatio X acquired temp. X initial pressure = the gauge
pressure; and .0019206 X 1940 X 14.7 == 54.77 Ibs.

By another formula, a convenient ratio is obtained by

absolute pressure 14.7

or = .023233; then, using the dif-

absolute temp. 520.66

ference of temperature as before, .028233 X 1940 == 54.77
Ibs. pressure.

By another formula, leaving out a small increment due
to specific heat at high temperatures:

Temperature Computations 53

Atmospheric pressure X absolute temp.
+ acquired temp.

_L.

Absolute temp. + initial temp.

absolute pressure due to the acquired temperature, from
which the atmospheric pressure is deducted for the
gauge pressure. Using, the foregoing example, we have

14.7 X 460.66 + 2000

- = 69.47 14.7 = 54.77, the gauge
460.66 + 60

pressure, 460.66 being the absolute temperature for zero
Fahrenheit.

For obtaining the volume pf expansion of a gas from
a given increment of heat, we have the approximate
formula :

Volume X absolute temp. + acquired temp.

II. - - heated

Absolute temp. + initial temp.

volume. In applying this formula to the foregoing ex-
ample, the figures become:

460.66 + 2000

I. x - = 4.72604 volumes.

460.66 + 60

From this last term the gauge pressure may be obtained
as follows:

III. 4.72604 X 14.7 = 69.47 Ibs. absolute 14.7 Ibs. at-
mospheric pressure 54.77 Ibs. gauge pressure ; which is
the theoretical pressure due to heating air in a confined
space, or at constant volume from 60 to 2000 F.

By inversion of the heat formula for absolute pressure
we have the formula for the acquired heat, derived from
combustion at constant volume from atmospheric pressure
to gauge pressure plus atmospheric pressure as derived
from Example L, by which the expression

absolute pressure X absolute temp. + initial temp,
initial absolute pressure

54 Aviation Engines

= absolute temperature + temperature of combustion,
from which the acquired temperature is obtained by sub-
tracting the absolute temperature.

69.47 X 460.66 + 60

Then, for example, = 2460.66, and

14.7

2460.66 460.66 = 2000, the theoretical heat of combus-
tion. The dropping of terminal decimals makes a small
decimal difference in the result in the different formulas.

HEAT AND ITS WORK

By Joule's law of the mechanical equivalent of heat,
whenever heat is imparted to an elastic body, as air or
gas, energy is generated and mechanical work produced
by the expansion of the air or gas. When the heat is im-
parted by combustion within a cylinder containing a mov-
able piston, the mechanical work becomes an amount
measurable by the observed pressure and movement of
the piston. The heat generated by the explosive elements
and the expansion of the non-combining elements of nitro-
gen and water vapor that may have been injected into the
cylinder as moisture in the air, and the water vapor
formed by the union of the oxygen of the air with the
hydrogen of the gas, all add to the energy of the work
from their expansion by the heat of internal combustion.
As against this, the absorption of heat by the walls of the
cylinder, the piston, and cylinder-head or clearance walls,
becomes a modifying condition in the force imparted to
the moving piston.

It is found that when any explosive mixture of air and
gas or hydrocarbon vapor is fired, the pressure falls far
short of the pressure computed from the theoretical effect
of the heat produced, and from gauging the expansion of
the contents of a cylinder. It is now well known that in
practice the high efficiency which is promised by theoret-
ical calculation is never realized; but it must always be

Heat and Its Work 55

remembered that the heat of combustion is the real agent,
and that the gases and vapors are but the medium for the
conversion of inert elements of power into the activity of
energy by their chemical union. The theory of combustion
has been the leading stimulus to large expectations with
inventors and constructors of explosive motors; its en-
tanglement with the modifying elements in practice has
delayed the best development in construction, and as yet
no really positive design of best form or action seems to
have been accomplished, although great progress has been
made during the past decade in the development of speed,
reliability, economy, and power output of the individual
units of this comparatively new power.

One of the most serious difficulties in the practical de-
velopment of pressure, due to the theoretical computations
of the pressure value of the full heat, is probably caused
by imparting the heat of the fresh charge to the balance
of the previous charge that has been cooled by expansion
from the maximum pressure to near the atmospheric
pressure of the exhaust. The retardation in the velocity
of combustion of perfectly mixed elements is now well
known from experimental trials with measured quantities;
but the principal difficulty in applying these conditions
to the practical work of an explosive engine where a ne-
cessity for a large clearance space cannot be obviated,
is in the inability to obtain a maximum effect from the
imperfect mixture and the mingling of the products of
the last explosion with the new mixture, which produces
a clouded condition that makes the ignition of the mass
irregular or chattering, as observed in the expansion lines
of indicator cards; but this must not be confounded with
the reaction of the spring in the indicator.

Stratification of the mixture has been claimed as taking
place in the clearance chamber of the cylinder; but this
is not a satisfactory explanation in view of the vortical
effect of the violent injection of the air and gas or vapor
mixture. It certainly cannot become a perfect mixture
in the time of a stroke of a high-speed motor of the two-

Aviation Engines

cycle class. In a four-cycle engine, making 1,500 revolu-
tions per minute, the injection and compression in any
one cylinder take place in one twenty-fifth of a second-
formerly considered far too short a time for a perfect
infusion of the elements of combustion but noAV very easily
taken care of despite the extremely high speed of numer-
ous aviation and automobile power-plants.

TABLE I. EXPLOSION AT CONSTANT VOLUME IN A CLOSED CHAMBER.

Dia-
gram
Curve
Fig. 8.

Mixture Injected.

Temp, of
Injection
Fahr.

Time
of Explo-
sion.
Second.

Observed
Gauge
Pressure.
Pounds.

Com-
puted
Temp.
Fahr.

1 volume gas to 14 volumes air.

0.45

40.

1,483

0.31

51.5

1,859

0.24

60.

2,195

0.17

61.

2,228

0.08

78.

2,835

0.06

87.

3,151

0.04

90.

3,257

0.055

91.

3,293

0.16 80.

2,871

In an examination of the times of explosion and the
corresponding pressures in both tables, it will be seen that
a mixture of 1 part gas to 6 parts air is the most effective
and will give the highest mean pressure in a gas-engine.
There is a limit to the relative proportions of illuminating
gas and air mixture that is explosive, somewhat variable,
depending upon the proportion of hydrogen in the gas.
With ordinary coal-gas, 1 of gas to 15 parts of air; and
on the lower end of the scale, 1 volume of gas to 2 parts
air, are non-explosive. With gasoline vapor the explosive
effect ceases at 1 to 16, and a saturated mixture of equal
volumes of vapor and air will not explode, while the most
intense explosive effect is from a mixture of 1 part vapor
to 9 parts air. In the use of gasoline and air mixtures
from a carburetor, the best effect is from 1 part saturated
air to 8 parts free air.

Heat and Its Work

TABLE II. PROPERTIES AND EXPLOSIVE TEMPERATURE OF A MIXTURE OF
ONE PART OF ILLUMINATING GAS OF 660 THERMAL UNITS PER CUBIC FOOT
WITH VARIOUS PROPORTIONS OF AIR WITHOUT MIXTURE OF CHARGE WITH
THE PRODUCTS OF A PREVIOUS EXPLOSION.

JJi

3 .

3 g

Specific Heat.
Heat Units Required
to Raise 1 Lb. 1 Deg.
Fahrenheit.

Heat to
Raise One
Cubic
Foot of

Ratio
Col.

3 w"

G**

C-i

Mixture

03 S IQ

2 **>
23.fi

TO jj

1 Deg.
Fahr.

'3
PC

Constant

^ 2 1

Pressure.

Volume.

6 to i

.074195

.2668

.1913

.014189

94.28

6644.6

.465

3090

. 7 to 1

.075012

.2628

.1882

.014116

82.

5844.4

.518

3027

8 to 1 .

.075647

.2598

.1858

.014059

73.33

5216.1

.543

2832

9 to 1 .

.076155

.2575

.1846

.014013

66.

4709.9

.56

2637

10 to 1 .

.076571

.2555

.1825

.013976

60.

4293.

.575

2468

11 to 1 .

.076917

.2540

.1813

.013945

55.

3944.

.585

2307

12 to 1 .

.077211

.2526

.1803

.013922

50.77

3646.7

.58

2115

The weight of a cubic foot of gas and air mixture as
given in Col. 2 is found by adding the number of volumes
of air multiplied by its weight, .0807, to one volume of gas
of weight .035 pound per cubic foot and dividing by the
total number of volumes; for example, as in the table,

.5192
6 X .0807 = = .074195 as in the first line, and so on

for any mixture or for other gases of different specific
weight per cubic foot. The heat units evolved by com-
bustion of the mixture (Col. 6) are obtained by dividing
the total heat units in a cubic foot of gas by the total

660
proportion of the mixture, = 94.28 as in the first line

of the table. Col. 5 is obtained by multiplying the weight
of a cubic foot of the mixture in Col. 2 by the specific heat

Col. 6

at a constant volume (Col. 4), = Col. 7 the total heat

Col. 5

58 Aviation Engines

ratio, of which Col. 8 gives the usual combustion efficiency
Col. 7 X Col. 8 gives the absolute rise in temperature
of a pure mixture, as given in Col. 9.

The many recorded experiments made to solve the dis-
crepancy between the theoretical and the actual heat de-
velopment and resulting pressures in the cylinder of an
explosive motor, to which much discussion has been given
as to the possibilities of dissociation and the increased
specific heat of the elements of combustion and non-com-
bustion, as well, also, of absorption and radiation of heat,
have as yet furnished no satisfactory conclusion as to
what really takes place within the cylinder walls. There
seems to be very little known about dissociation, and
somewhat vague theories have been advanced to explain
the phenomenon. The fact is, nevertheless, apparent as
shown in the production of water and other producer
gases by the use of steam in contact with highly incan-
descent fuel. It is known that a maximum explosive
mixture of pure gases, as hydrogen and oxygen or car-
bonic oxide and oxygen, suffers a contraction of one-third
their volume by combustion to their compounds, steam or
carbonic acid. In the explosive mixtures in the cylinder
of a motor, however, the combining elements form so
small a proportion of the contents of the cylinder that
the shrinkage of their volume amounts to no more than
3 per cent, of the cylinder volume. This by no means
accounts for the great heat and pressure differences be-
tween the theoretical and actual effects.

CONVERSION OF HEAT TO POWER

. The utilization of heat in any heat-engine has long
been a theme of inquiry and experiment with scientists
and engineers, for the purpose of obtaining the best prac-
tical conditions and construction of heat-engines that would
represent the highest efficiency or the nearest approach
to the theoretical value of heat, as measured by empirical
laws that have been derived from experimental researches
relating to its ultimate volume. It is well known that the

Requisites for Best Power Effect 59

steam-engine returns only from 12 to 18 per cent, of the
power due to the heat generated by the fuel, about 25
per cent, of the total heat being lost in the chimney, the
only use of which is to create a draught for the fire; the
balance, some 60 per cent., is lost in the exhaust and by
radiation. The problem of utmost utilization of force
in steam has nearly reached its limit.

The internal-combustion system of creating power is
comparatively new in practice, and is but just settling
into definite shape by repeated trials and modification of
details, so as to give somewhat reliable data as to what
may be expected from the rival of the steam-engine as
a prime mover. For small powers, the gas, gasoline, and
petroleum-oil engines are forging ahead at a rapid rate,
filling the thousand wants of manufacture and business
for a power that does not require expensive care, that
is perfectly safe at all times, that can be used in any place
in the wide world to 'which its concentrated fuel can be
conveyed, and that has eliminated the constant handling
of crude fuel and water.

REQUISITES FOR BEST POWER EFFECT

The utilization of heat in a gas-engine is mainly due
to the manner in which the products entering into com-
bustion are distributed in relation to the movement of
the piston. The investigation of the foremost exponent
of the theory of the explosive motor was prophetic in
consideration of "the later realization of the best condi-
tions under which these motors can be made to meet the
requirements of economy and practicability. As early as
1862, Beau de Kocha announced, in regard to the coming
power, that four requisites were the basis of operation
for economy and best effect. 1. The greatest possible
cylinder volume with the least possible cooling surface,
2. The greatest possible rapidity of expansion. Hence,
high speed. 3. The greatest possible expansion. Long
stroke. 4. The greatest possible pressure at the com-
mencement of expansion. High compression.

CHAPTER III

Efficiency of Internal Combustion Engines Various Measures o-f Effi-
. ciency Temperatures and Pressures Factors Governing Economy
Losses in Wall Cooling Value of Indicator Cards Compres-
sion in Explosive Motors Factors Limiting Compression Causes
of Heat Losses and Inefficiency Heat Losses to Cooling Water.

EFFICIENCY OF INTERNAL COMBUSTION ENGINES

EFFICIENCIES are worked out through intricate formulas
for a variety of theoretical and unknown conditions of
combustion in the cylinder: ratios of clearance and cyl-
inder volume, and the uncertain condition of the products
of combustion left from the last impulse and the wall
temperature. But they are of but little value, except as
a mathematical inquiry as to possibilities. The real com-
mercial efficiency of a gas or gasoline-engine depends upon
the volume 'of gas or liquid at some assigned cost, re-
quired per actual brake horse-power per hour, in which
an indicator card should show that the mechanical action
of the valve gear and ignition was as perfect as practi-
cable, and that the ratio of clearance, space, and cylinder
volume gave a satisfactory terminal pressure and com-
pression: i.e., the difference between the power figured
from the indicator card and the brake power being the
friction loss of the engine.

In four-cycle motors of the compression type, the effi-
ciencies are greatly advanced by compression, producing
a more complete infusion of the mixture of gas or vapor
and air, quicker firing, and far greater pressure than is
possible with the two-cycle type previously described. In
the practical operation of the gas-engine during the past
twenty years, the gas-consumption efficiencies per indi-
cated horse-power have gradually risen from 17 per cent,
to a maximum of 40 per cent, of the theoretical heat, and

Various Measures of Efficiency 61

this has been done chiefly through a decreased combustion
chamber and increased compression the compression hav-
ing gradually increased in practice from 30 Ibs. per square
inch to above 100; but there seems to be a limit to com-
pression, as the efficiency ratio decreases with greater in-
crease in compression. It has been shown that an ideal
efficiency of 33 per cent, for 38 Ibs. compression will in-
crease to 40 per cent, for 66 Ibs., and 43 per cent, for 88
Ibs. compression. On the other hand, greater compression
means greater explosive pressure and greater strain on
the engine structure, which will probably retain in future
practice the compression between the limits of 40 and 90
Ibs. except in super-compression engines intended for
high altitude work where compression pressures as high
as 125 pounds have been used.

In .experiments made by Dugald Clerk, in England,
with a combustion chamber equal to 0.6 of the space swept
by the piston, with a compression of 38 Ibs., the consump-
tion of gas was 24 cubic feet per indicated horse-power
per hour. With 0.4 compression space and 61 Ibs. com-
pression, the consumption of gas was 20 cubic feet per
indicated horse-power per hour; and with 0.34 compres-
sion space and 87 Ibs. compression, the consumption of
gas fell to 14.8 cubic feet per indicated horse-power per
hour the actual efficiencies being respectively 17, 21, and
25 per cent. This was with a Crossley four-cycle engine.

VARIOUS MEASURES OF EFFICIENCY

The efficiencies in regard to power in a heat-engine
may be divided into four kinds, as follows: I. The first
is known as the maximum theoretical efficiency of a per-
fect engine (represented by the lines in the indicator dia-

T! T

gram). It is expressed by the formula and shows

the work of a perfect cycle in an engine working between
the received temperature+ absolute temperature (TJ and

62 Aviation Engines

the initial atmospheric temperature + absolute tempera-
ture (T ). II. The second is the actual heat efficiency,
or the ratio of the heat turned into work to the total heat
received by the engine. It expresses the indicated horse-
power. III. The third is the ratio between the second
or actual heat efficiency and the first or maximum theo-
retical efficiency of a perfect cycle. It represents the
greatest possible utilization of the power of heat in an
internal-combustion engine. IV. The fourth is the me-

100 Jo
Supplied

3 Useful
Work

5% Engjne
Friction

Lost to
Cooling Water

Rejected in Exhaust and Radiation

Fig. 12. Graphic Diagram Showing Approximate Utilization of Fuel
Burned in Internal-Combustion Engine.

chanical efficiency. This is the ratio between the actual
horse-power delivered by the engine through a dyna-
mometer or measured by a brake (brake horse-power),
and the indicated horse-power. The difference between
the two is the power lost by engine friction. In regard
to the general heat efficiency of the materials of power
in explosive engines, we find that with good illuminating
gas the practical efficiency varies from 25 to 40 per cent. ;
kerosene-motors, 20 to 30; gasoline-motors, 20 to 32; acet-
ylene, 25 to 35; alcohol, 20 to 30 per cent, of their heat
value. The great variation is no doubt due to imperfect
mixtures and variable conditions of the old and new charge
in the cylinder; uncertainty as to leakage and the perfec-

Temperatures and Pressures 63

tion of combustion. In the Diesel motors operating under
high pressure, up to nearly 500 pounds, an efficiency of
36 per cent, is claimed.

The graphic diagram at Fig. 12 is of special value as
it shows clearly how the heat produced by charge combus-
tion is expended in an engine of average design.

On general principles the greater difference between
the heat of combustion and the heat at exhaust is the
relative measure of the heat turned into work, which
represents the degree of efficiency without loss during
expansion. The mathematical formulas appertaining to
the computation 'of the element of heat and its work in
an explosive engine are in a large measure dependent
upon assumed values, as the conditions of the heat of
combustion are made uncertain by the mixing of the fresh
charge with the products of a previous combustion, and
by absorption, radiation, and leakage. The computation
of the temperature from the observed pressure may be
made as before explained, but for compression-engines
the needed starting-points for computation are very un-
certain, and can only be approximated from the exact
measure and value of the elements of combustion in a
cylinder charge.

TEMPERATURES AND PRESSURES

Owing to the decrease from atmospheric pressure in
the indrawing charge of the cylinder, caused by valve and
frictional obstruction, the compression seldom starts above
13 Ibs. absolute, especially in high-speed engines. Col. 3
in the following table represents the approximate absolute
compression pressure for the clearance percentage and
ratio in Cols. 1 and 2, while Col. 4 indicates the gauge
pressure from the atmospheric line. The temperatures in
Col. 5 are due to the compression in Col. 3 from an as-
sumed temperature of 560 F. in the mixture of the fresh
charge of 6 air to 1 gas with the products of combustion
left in the clearance chamber from the exhaust stroke of
a medium-speed motor. This temperature is subject to

Aviation Engines

considerable variation from the difference in the heat-
unit power of the gases and vapors used for explosive
power, as also of the cylinder-cooling effect. In Col. 6 is
given the approximate temperatures of explosion for a
mixture of air 6 to gas 1 of 660 heat units per cubic foot,
for the relative values of the clearance ratio in Col. 2 at
constant volume.

TABLE III. GAS-ENGINE CLEARANCE RATIOS, APPROXIMATE COMPRESSION,
TEMPERATURES OF EXPLOSION AND EXPLOSIVE PRESSURES WITH A MIX-
TURE OF GAS OF 660 HEAT UNITS PER CUBIC FOOT AND MIXTURE OF GAS
1 TO 6 OF AIR.

"og.S

III

|J3

0>|

U |

sHl

i-i

S 1

S*~ fl
ex c ^

1 a

flj

rt+g

fffi

ill .

1 j*

ffi

-2 -

JlJ

Q< 3
<Jrt

SFJ

Si?

< ei

ill

2 M

J 13 I ^^

g i

O.-^<j<

<J Q

|flA

|3fe

Lhs.

Deg.

.Lbs.

Lbs.

Deg.

.50

57.

42.

' 822.

2488

*169

144

2027

.444

3.25

65.

50.

846.

2568

197

182

2107

.40

3.50

70.

55.

868.

2638

212

197

2177

.363

3.75

77.

62.

889.

2701

234

219

2240 .

.333

84.

69.

910.

2751

254

239

2290

.285

4.50

102.

88.

955.

2842

303

288

2381

.25

114.

99.

983.

2901

336

321

2440

FACTORS GOVERNING ECONOMY

In view of the experiments in this direction, it clearly
shows that in practical work, to obtain the greatest econ-
omy per effective brake horse-power, it is necessary: 1st.
To transform the heat into work with the greatest rapid-
ity mechanically allowable. This means high piston speed.
2d. To have high initial compression. 3d. To reduce the
duration of contact between the hot gases and the cylinder
walls to the smallest amount possible; which means short
stroke and quick speed, with a spherical cylinder head.
4th. To adjust the temperature of the jacket water to

Losses in Wall Cooling 65

obtain the most economical output of actual power. This
means water-tanks or water-coils, with air-cooling surfaces
suitable and adjustable to the most economical requirement
of the engine, which by late trials requires the jacket water
to be discharged at about 200 F. 5th. To reduce the
wall surface of the clearance space or combustion chamber
to the smallest possible area, in proportion to its required
volume. This lessens the loss of the heat of combustion by
exposure to a large surface, and allows of a higher mean
wall temperature to facilitate the heat of compression.

LOSSES IN WALL COOLING

In an experimental investigation of the efficiency of a
gas-engine under variable piston speeds made in France,
it w T as found that the useful effect increases with the ve-
locity of the piston that is, with the rate of expansion
of the burning gases with mixtures of uniform volumes;
so that the variations of time of complete combustion
at constant pressure, and the variations due to speed, in
a way compensate in their efficiencies. The dilute mix-
ture, being slow burning, will have its time and pressure
quickened by increasing the speed.

Careful trials give unmistakable evidence that the use-
ful effect increases with the velocity of the piston that
is, with the rate of expansion of the burning gases. The
time necessary for the explosion to become complete and
to attain its maximum pressure depends not only on the
composition of the mixture, but also upon the rate of ex-
pansion. This has been verified in experiments with a
high-speed motor, at speeds from 500 to 2,000 revolutions
per minute, or piston speeds of from 16 to 64 feet per
second. The increased speed of combustion due to in-
creased piston speed is a matter of great importance to
builders of gas-engines, as well as to the users, as indi-
cating the mechanical direction of improvements to lessen
the wearing strain due to high speed and to lighten the
vibrating parts with increased strength, in order that the

66 Aviation Engines

balancing of high-speed engines may be accomplished with
the least weight.

From many experiments made in Europe and in the
United States, it has been conclusively proved that ex-
cessive cylinder cooling by the water-jacket results in a
marked loss of efficiency. In a series of experiments with
a simplex engine in France, it was found that a saving
of 7 per cent, in gas consumption per brake horse-power
was made by raising the temperature of the jacket water
from 141 to 165 F. A still greater saving was made in
a trial with an Otto engine by raising the temperature of
the jacket water from 61 to 140 F. it being 9.5 per
cent, less gas per brake horse-power.

It has been stated that volumes of similar cylinders
increase as the cube of their diameters, while the surface
of their cold walls varies as the square of their diameters ;
so that for large cylinders the ratio of surface to volume
is less than for small ones. This points to greater econ-
omy in the larger engines. The study of many experi-
ments goes to prove that combustion takes place gradually
in the gas-engine cylinder, and that the rate of increase
of pressure or rapidity of firing is controlled by dilution
and compression of the mixture, as well as by the rate
of expansion or piston speed. The rate of combustion
also depends on the size and shape of the explosion cham-
ber, and is increased by the mechanical agitation of the
mixture during combustion, and still more by the mode
of firing.

VALUE OF INDICATOR CARDS

To the uninitiated, indicator cards are considerable
of a mystery; to those capable of reading them they form
an index relative to the action of any engine. An indi-
cator card, such as shown at Fig. 13, is merely a graphical
representation of the various pressures existing in the
cylinder for different positions of the piston. The length
is to some scale that represents the stroke of the piston.
During the intake stroke, the pressure falls below the

Value of Indicator Cards

atmospheric line. During compression, the curve gradu-
ally becomes higher owing to increasing pressure as the
volume is reduced. After ignition the pressure line moves

F Max 1 * Press.

& Temp*

Actual Indicator

J)ia(jram from

Otto Engine.

JZngine]

Dia.

Miri? Press.

Atr,

Admission:

T7tis length is proportional ..totes, strode of Engine-
Tig. 13. Otta Four-Cycle Card.

upward almost straight, then as the piston goes down on
the explosion stroke, the pressure falls gradually to the
point of exhaust valve, opening when the sudden release
o't the imprisoned gas causes a reduction in pressure to
nearly atmospheric. An indicator card, or a series of

V...

Fig. 14-. Diesel Motor Card.

them, will always show by its lines the normal or defective
condition of the inlet valve and passages; the actual line
of compression; the firing moment; the pressure of ex-
plosion; the velocity of combustion; the normal or defec-
tive line of expansion, as measured by the adiabatic curve,

68 Aviation Engines

and the normal or defective operation of the exhaust
valve, exhaust passages, and exhaust pipe. In fact, all
the cycles of an explosive motor may be made a practical
study from a close investigation of the lines of an indi-
cator card.

A most unique card is that of the Diesel motor (Fig.
14), which involves a distinct principle in the design and
operation of internal-combustion motors, in that instead
of taking a mixed charge for instantaneous explosion, its
charge primarily is of air and its compression to a press-
ure at which a temperature is attained above the igniting
point of the fuel, then injecting the fuel under a still
higher pressure by which spontaneous combustion takes
place gradually with increasing volume over the compres-
sion for part of the stroke or until the fuel charge is con-
sumed. The motor thus operating between the pressures
of 500 and 35 Ibs. per square inch, with a clearance of
about 7 per cent., has given an efficiency of 36 per cent,
of the total heat value of kerosene oil.

COMPRESSION IN EXPLOSIVE MOTORS

That the compression in a gas, gasoline, or oil-engine
has a direct relation to the power obtained, has been long
known to experienced builders, having been suggested by
M. Beau de Eocha, in 1862, and afterward brought into
practical use in the four-cycle or Otto type about 1880.
The degree of compression has had a growth from zero,
in the early engines, to the highest available due to the
varying ignition temperatures of the different gases and
vapors used for explosive fuel, in order to avoid prema-
ture explosion from the heat of compression. Much of
the increased power for equal-cylinder capacity is due to
compression of the charge from the fact that the most
powerful explosion of gases, or of any form of explosive
material, takes place when the particles are in the closest
contact or cohesion with one another, less energy in this
form being consumed by the ingredients themselves to
bring about their chemical combination, and consequently

Value of Compression

more energy is given out in useful or available work.
This is best shown by the ignition of gunpowder, which,
when ignited in the open air, burns rapidly, but without
explosion, an explosion only taking place if the powder
be confined or compressed into a small space.

.20

.222

Piston Stroke Volume

.25 .285 .333 .363 .40 .444 .50

Fig. 15. Diagram of Heat in the Gas Engine Cylinder.

In a gas or gasoline-motor with a small clearance or
compression space with high compression the surface
with which the burning gases come into contact is much
smaller in comparison with the compression space in a
low-compression motor. Another advantage of a high-
compression motor is that on account of the smaller clear-
ance of combustion space less cooling water is required
than with a low-compression motor, as the temperature,

70 Aviation Engines

and consequently the pressure, falls more rapidly. The
loss of heat through the water-jacket is thus less in the
case of a high-compression than in that of a low-compres-
sion motor. In the non-compression type of motor the
best results were obtained with a charge of 16 to 18 parts
of gas and 100 parts of air, while in the compression type
the best results are obtained with an explosive mixture
of 7 to 10 parts of gas and 100 parts of air, thus showing
that by the utilization of compression a weaker charge
with a greater thermal efficiency is permissible.

It has been found that the explosive pressure resulting
from the ignition of the charge of gas or gasoline-vapor
and air in the gas-engine cylinder is about 4^ times the
pressure prior to ignition. The difficulty about getting
high compression is that if the pressure is too high the
charge is likely to ignite prematurely, as compression
always results in increased temperature. The cylinder
may become too hot, a deposit of carbon, a projecting
electrode or plug body in the cylinder may become in-
candescent and ignite the charge which has been exces-
sively heated by the high compression and mixture of
the hot gases of the previous explosion.

FACTORS LIMITING COMPRESSION

With gasoline-vapor and air the compression should not
be raised above about 90 to 95 pounds to the square inch,
many manufacturers not going above 65 or 70 pounds.
For natural gas the compression pressure may easily be
raised to from 85 to 100 pounds per square inch. For
gases of low calorific value, such as blast-furnace or pro-
ducer-gas, the compression may be increased to from 140
to 190 pounds. In fact the ability to raise the compres-
sion to a high point with these gases is one of the prin-
cipal reasons for their successful adoption for gas-engine
use. In kerosene injection engines the compression of 250
pounds per square inch has been used with marked econ-
omy. Many troubles in regard to loss of power and in-
crease of fuel have occurred and will no doubt continue,

Factors Limiting Compression

owing to the wear of valves, piston, and cylinder, which
produces a loss in compression and explosive pressure
and a waste of fuel by leakage. Faulty adjustment of
valve movement is also a cause of loss of power; which
may be from tardy closing of the inlet-valve or a too early
opening of the exhaust-valve.

The explosive pressure varies to a considerable amount
in proportion to the compression pressure by the differ-
ence in fuel value and the proportions of air mixtures,
so that for good illuminating gas the explosive pressure
may be from 2.5 to 4 times the compression pressure.
For natural gas 3 to 4.5, for gasoline 3 to 5, for producer-
gas 2 to 3, and for kerosene by injection 3 to 6.

The compression temperatures, although well known
and easily computed from a known normal temperature
of the explosive mixture, are subject to the effect of the
uncertain temperature of the gases of the previous ex-
plosion remaining in the cylinder, the temperature of its
walls, and the relative volume of the charge, whether full
or scant; which are terms too variable to make any com-
putations reliable or available.

For the theoretical compression temperatures from a
known normal temperature, we append a table of the rise
in temperature for the compression pressures in the fol-
lowing table:

TABLE IV. COMPRESSION TEMPERATURES FROM A NORMAL TEMPERATURE OF
60 DEGREES FAHRENHEIT

100 Ibs. gauge . 484

90 Ibs. gauge 459

80 Ibs. gauge 433

70 Ibs. gauge 404

60 Ibs. gauge 373

50 Ibs. gauge. . 339

40 Ibs. gauge 301

30 Ibs. gauge 258

CHART FOR DETERMINING COMPRESSION PRESSURES

A very useful chart (Fig. 16) for determining com-
pression pressures in gasoline-engine cylinders for vari-
ous ratios of compression space to total cylinder volume
is given by P. S. Tice, and described in the Chilton Au-
tomobile Directory by the originator as follows:

Aviation Engines

It is many times desirable to have at hand a conve-
nient means for at once determining with accuracy what
the compression pressure will be in a gasoline-engine cyl-
inder, the relationship between the volume of the com-
pression space and the total cylinder volume or that swept
by the piston being known. The curve at Fig. 16 is
offered as such a means. It is based- on empirical data

Fig. 16. Chart Showing Relation Between Compression Volume
and Pressure.

gathered from upward of two dozen modern automobile
engines and represents what may be taken to be the results
as found in practice. It is usual for the designer to find
compression pressure values, knowing the volumes from
the equation

which is for adiabatic compression of air. Equation (1)
is right enough in general form but gives results which

Determining Compression Pressures 73

are entirely too high, as almost all designers know from
experience. The trouble lies in the interchange of heat
between the compressed gases and the cylinder walls, in
the diminution of the exponent (1.4 in the above) due to the
lesser ratio of specific heat of gasoline vapor and in the
transfer of heat from the gases which are being com-
pressed to whatever fuel may enter the cylinder in an
unvaporized condition. Also, there is always some piston
leakage, and, if the form of the equation (1) is to be
retained, this also tends to lower the value of the ex-
ponent. From experience with many engines, it appears
that compression reaches its highest value in the cylinder
for but a short range of motor speeds, usually during the
mid-range. Also, it appears that, at those speeds at which
compression shows its highest values, the initial pressure
at the start of the compression stroke is from .5 to .9 Ib.
below atmospheric. Taking this latter loss value, which
shows more often than those of lesser value, the compres-
sion is seen to start from an initial pressure of 13.9 Ibs.
per sq. in. absolute.

Also, experiment shows that if the exponent be given
the value 1.26, instead of 1.4, the equation will embrace
all heat losses in the compressed gas, and compensate for
the changed ratio of specific heats for the mixture and
also for all piston leakage, in the average engine with
rings in good condition and tight. In the light of the
foregoing, and in view of results obtained from its use,
the above curve is offered values of P 2 being found
from the equation

/VA 1 ' 26

P 2 = 13.8 (~J

In using this curve it must be remembered that press-
ures are absolute.. Thus: suppose it is desired to know
the volumetric relationships of the cylinder for a com-
pression pressure of 75 Ibs. gauge. Add atmospheric
pressure to the desired gauge pressure 14.7 + 75 = 89.7
Ibs. absolute. Locate this pressure on the scale of ordi-

74 Aviation Engines

nates and follow horizontally across to the curve and then
vertically downward to the scale of abscissas, where the
ratio of the combustion chamber volume to the total cyl-
inder volume is given, which latter is equal to the sum of
the combustion chamber volume and that of the piston
sweep. In the above case it is found that the combustion
space for a compression pressure of 75 Ibs. gauge will be
.225 of the total cylinder volume, or .225 -~ 775 = .2905
of the piston sweep volume. Conversely, knowing the
volumetric ratios, compression pressure can be read di-
rectly by proceeding from the scale of abscissas verti-
cally to the curve and thence horizontally to the scale of
ordinates.

CAUSES OF HEAT LOSS AND INEFFICIENCY IN EXPLOSIVE MOTORS

The difference realized in the practical operation of
an internal combustion heat engine from the computed
effect derived from the values of the explosive elements
is probably the most serious difficulty that engineers have
encountered in their endeavors to arrive at a rational
conclusion as to where the losses were located, and the
ways and means of design that would eliminate the causes
of loss and raise the efficiency step by step to a reason-
able percentage of the total efficiency of a perfect cycle.

An authority on the relative condition of the chemical
elements under combustion in closed cylinders attributes
the variation of temperature shown in the fall of the ex-
pansion curve, and the suppression or retarded evolution
of heat, entirely to the cooling action of the cylinder walls,
and to this nearly all the phenomena hitherto obscure in
the cylinder of a gas-engine. Others attribute the great
difference between the theoretical temperature of combus-
tion and the actual temperature realized in the practical
operation of the gas-engine, a loss of more than one-half
of the total heat energy of the combustibles, partly to the
dissociation of the elements of combustion at extremely
high temperatures and their reassociation by expansion
in the cylinder, to account for the supposed continued

Causes of Heat Loss

combustion and extra adiabatic curve of the expansion
line on the indicator card.

The loss of heat to the walls of the cylinder, piston,
and clearance space, as regards the proportion of wall
surface to the volume, has gradually brought this point

Fig. 17. The Thompson Indicator, an Instrument for Determining Com-
pressions and Explosion Pressure Values and Recording Them on Chart.

to its smallest ratio in the concave piston-head and glob-
ular cylinder-head, with the smallest possible space in the
inlet and exhaust passage. The wall surface of a cylin-
drical clearance space or combustion chamber of one-half
its unit diameter in length is equal to 3.1416 square units,
its volume but 0.3927 of a cubic unit ; while the same wall

76 Aviation Engines

surface in a spherical form has a volume of 0.5236 of a
cubic unit. It will be readily seen that the volume is in-
creased 33% per cent, in a spherical over a cylindrical
form for equal wall surfaces at the moment of explosion,
when it is desirable that the greatest amount of heat is
generated, and carrjdng with it the greatest possible press-
ure from which the expansion takes place by the movement
of the piston.

The spherical form cannot continue during the stroke
for mechanical reasons; therefore some proportion of
piston stroke of cylinder volume must be found to cor-
respond with a spherical form of the combustion chamber
to produce the least loss of heat through the walls during

Fig. 18. Spherical Combustion
Chamber.

Fig. 19. Enlarged Combustion
Chamber.

the combustion and expansion part of the stroke. This
idea is illustrated in Figs. 18 and 19, showing how the
relative volumes of cylinder stroke and combustion cham-
ber may be varied to suit the requirements due to the
quality of the elements of combustion.

Although the concave piston-head shows economy in
regard to the relation of the clearance volume to the wall
area at the moment of explosive combustion, it may be
clearly seen that its concavity increases its surface area
and its capacity for absorbing heat, for which there is
no provision for cooling the piston, save its contact with
the walls of the cylinder and the slight air cooling of its
back by its reciprocal motion. For this reason the con-
cave piston-head has not been generally adopted and the
concave cylinder-head, as shown in Fig. 19, with a flat

Mercedes Aviation Engine

Inlet Valve

Exhaust

Valve

Concave.
Piston Top

,,~ Approximately
Spherical
Chamber

.-Carburetor

^Connecting
Rod

" OH Sump

Fig. 20. Mercedes Aviation Engine Cylinder Section Showing Approximately
Spherical Combustion Chamber and Concave Piston Top.

78 Aviation Engines

piston-head is the latest and best practice in airplane
engine construction.

The practical application of the principle just outlined
to one of the most efficient airplane motors ever designed,
the Mercedes, is clearly outlined at Fig. 20.

HEAT LOSSES TO COOLING WATER

The mean temperature of the wall surface of the com-
bustion chamber and cylinder, as indicated by the tem-
peratures of the circulating water, has been found to be
an important item in the economy of the gas-engine.
Dugald Clerk, in England, a high authority in practical
work with the gas-engine, found that 10 per cent, of the
gas for a stated amount of power was saved by using
water at a temperature in. which the ejected water from
the cylinder- jacket was near the boiling-point, and ven-
tures the opinion that a still higher temperature for the
circulating water may be used as a source of economy.
This could be made practical in the case of aviation en-
gines by adjusting the air-cooling surface of the radiator
so as to maintain the inlet water at just below the boiling
point, and by the rapid circulation induced by the pump
pressure, to return the water from the cylinder- jacket a
few degrees above the boiling point. The thermal dis-
placement systems of cooling employed in automobiles
are working under more favorable temperature conditions
than those engines in which cooling is more energetic.

For a given amount of heat taken from the cylinder
by the largest volume of circulating water, the difference
in temperature between inlet and outlet of the water 1
jacket should be the least possible, and this condition of
the water circulation gives a more even temperature to
all parts of the cylinder; while, on the contrary, a cold-
water supply, say at 60 F., so slow as to allow the ejected
water to flow off at a temperature near the boiling-point,
must make a great difference in temperature between the
bottom and top of the cylinder, with a loss in economy

Heat Losses to Cooling Water 79

in gas and other fuels, as well as in water, if it is ob-
tained by measurement.

From the foregoing considerations of losses and ineffi-
ciencies, we find that the practice in motor design and
construction has not yet reached the desired perfection
in its cycular operation. Step by step improvements have
been made with many changes in design though many
.have been without merit as an improvement, farther than
to gratify the longings of designers for something dif-
ferent from the other thing, 'and to establish a special
construction of their own. These efforts may in time
produce a motor of normal or standard design for each
kind of fuel that will give the highest possible efficiency
for all conditions of service.

CHAPTER IV

Engine Parts and Functions Why Multiple Cylinder Engines Are
Best Describing Sequence of Operations Simple Engines Four
and Six Cylinder Vertical Tandem Engines Eight and Twelve
Cylinder V Engines Radial Cylinder Arrangement Rotary Cylin-
der Forms.

ENGINE PARTS AND FUNCTIONS

THE principal elements of a gas engine are not diffi-
cult to understand and their functions are easily denned.
In place of the barrel of the gun one has a smoothly
machined cylinder in which a small cylindrical or barrel-
shaped element fitting the bore closely may be likened to
a bullet or cannon ball. It differs in this important
respect, however, as while the shot is discharged from
the mouth of the cannon the piston member sliding inside
of the main cylinder cannot leave it, as its movements
back and forth from the open to the closed end and back
again are limited by simple mechanical connection or link-
age which comprises crank and connection rod. It is by
this means that the reciprocating movement of the piston
is transformed into a rotary motion of the crank-shaft.

The fly-wheel is a heavy member attached to the crank-
shaft of an automobile engine which has energy stored
in its rim as the member revolves, and the momentum
of this revolving mass tends to equalize the intermittent
pushes on the piston head produced by the explosion of
the gas in the cylinder. In aviation engines, the weight
of the propeller or that of rotating cylinders themselves
performs the duty of a fly-wheel, so no separate member
is needed. If some explosive is placed in the chamber
formed by the piston and closed end of the cylinder and
exploded, the piston would be the only part that would
yield to the pressure which would produce a downward
movement. As this is forced down the crank-shaft is

82 Aviation Engines

turned by the connecting rod, and as this part is hinged
at both ends it is free to oscillate as the crank turns, and
thus the piston may slide back and forth while the crank-
shaft is rotating or describing a curvilinear path.

In addition to the simple elements described it is evi-
dent that a gasoline engine must have other parts. The
most important of these are the valves, of which there are
generally two to each cylinder. One closes the passage
connecting to the gas supply and opens during one stroke
of the piston in order to let the explosive gas into the
combustion chamber. The other member, or exhaust
valve, serves as a cover for the opening through which
the burned gases can leave the cylinder after their work
is done. The spark plug is a simple device which may
be compared to the fuse or percussion cap of the cannon.
It permits one to produce an electric spark in the cyl-
inder when the piston is at the best point to utilize the
pressure which obtains when the compressed gas is fired.
The valves are open one at a time, the inlet valve being
lifted from its seat while -the cylinder is filling and the
exhaust valve is opened when the cylinder is being cleared.
They are normally kept seated by means of compression
springs. In the simple motor shown at Fig. 5, the exhaust
valve is operated by means of a pivoted bell crank rocked
by a cam which turns at half the speed of the crank-shaft.
The inlet valve operates automatically, as will be ex-
plained in proper sequence.

In order to obtain a perfectly tight combustion cham-
ber, both intake and exhaust valves are closed before the
gas is ignited, because all of the pressure produced by
the exploding gas is to be directed against the top of
the movable piston. When the piston reaches the bottom
of its power stroke, the exhaust valve is lifted by means
of the bell crank which is rocked because of the point or
lift on the cam. The cam-shaft is driven by positive
gearing and revolves at half the engine speed. The ex-
haust valve remains open during the whole of the return
stroke of the piston, and as this member moves toward

Why Multiple Cylinder Forms Are Best 83

the closed end of the cylinder it forces out burned gases
ahead of it, through the passage controlled by the exhaust
valve. The cam-shaft is revolved at half the engine speed
because the exhaust valve is raised from its seat during
only one stroke out of four, or only once every two revo-
lutions. Obviously, if the cam was turned at the same
speed as the crank-shaft it would remain open once every
revolution, whereas the burned gases are expelled from
the individual cylinders only once in two turns of the
crank-shaft.

WHY MULTIPLE CYLINDER FORMS ARE BEST

Owing to the vibration which obtains from the heavy
explosion in the large single-cylinder engines used for
stationary power other forms were evolved in which the
cylinder was smaller and power obtained by running the
engine faster, but these are suitable only for very low
powers.

When a single-cylinder engine is employed a very
heavy fly-wheel is needed to carry the moving parts
through idle strokes necessary to obtain a power im-
pulse. For this reason automobile and aircraft design-
ers must use more than one cylinder, and the tendency
is to produce power by frequently occurring light im-
pulses rather than by a smaller number of explosions
having greater force. "When a single-cylinder motor is
employed the construction is heavier than is needed with
a multiple-cylinder form. Using two or more cylinders
conduces to steady power generation and a lessening of
vibration. Most modern motor cars employ four-cylinder
engines because a power impulse may be secured twice
every revolution of the crank-shaft, or a total of four-
power strokes during two revolutions. The parts are so
arranged that while the charge of gas in one cylinder is
exploding, those which come next in firing order are com-
pressing, discharging the inert gases and drawing in a
fresh charge respectively. When the power stroke is
completed in one cylinder, the piston in that member in

84 Aviation Engines

which a charge of gas has just been compressed has
reached the top of its stroke and when the gas is ex-
ploded the piston is reciprocated and keeps the crank-
shaft turning. When a multiple-cylinder engine is used
the fly-wheel can be made much lighter than that of the
simpler form and eliminated altogether in some designs.
In fact, many modern multiple-cylinder engines develop-
ing 300 horse-power weigh less than the early single- and
double-cylinder forms which developed but one-tenth or
one-twentieth that amount of energy.

DESCRIBING SEQUENCE OF OPERATIONS

Eef erring to Fig. 22, A, the sequence of operation in
a single-cylinder motor can be easily understood. As-
suming that the crank-shaft is turning in the direction
of the arrow, it will be seen that the intake stroke comes
first, then the compression, which is followed by the power
impulse, and lastly the exhaust stroke. If two cylinders
are used, it is possible to balance the explosions in such
a way that one will occur each revolution. This is true
with either one of two forms of four-cycle motors. At
B, a two-cylinder vertical engine using a crank- shaft in
which the crank-pins are on the same plane is shown.
The two pistons move up and down simultaneously. Be-
f erring to the diagram describing the strokes, and assum-
ing that the outer circle represents the cycle of operations
in one cylinder while the inner circle represents the se-
quence of events in the other cylinder, while cylinder
No. 1 is taking in a fresh charge of gas, cylinder No. 2
is exploding. When cylinder No. 1 is compressing, cyl-
inder No. 2 is exhausting. During the time that the charge
in cylinder No. 1 is exploded, cylinder No. 2 is being filled
with fresh^gas. While the exhaust gases are being dis-
charged from cylinder No. 1, cylinder No. 2 is compressing
the gas previously taken.

The same condition obtains when the crank-pins are
arranged a.t one hundred and eighty degrees and the cyl-
inders are opposed, as shown at C. The reason that the

Sequence of Operations

Single Cylinder

HPU

Two Cylinder Vertical
Cranhpins on Same Plans

Two Cylinder, Opposed
Crmnhpins At 180 Degrees

Fig. 22. Diagrams Illustrating Sequence of Cycles in One- and Two-Cylinder
Engines Showing More Uniform Turning Effort on Crank-Shaft with
Two-Cylinder Motors.

86 Aviation Engines

two-cylinder opposed motor is more popular than that
having two vertical cylinders is that it is difficult to bal-
ance the construction shown at B, so that the vibration
will not be excessive. The two-cylinder opposed motor
has much less vibration than the other form, and as the
explosions occur evenly and the motor is a simple one
to construct, it has been very popular in the past on
light cars and has received limited application on some
early, light airplanes.

To demonstrate very clearly the advantages of multi-
ple-cylinder engines the diagrams at Fig. 23 have been
prepared. At A, a three-cylinder motor, having crank-
pins at one hundred and twenty degrees, which means that
they are spaced at thirds of the circle, we have a form
of construction that gives a more even turning than that
possible with -a two-cylinder engine. Instead of one ex-
plosion per revolution of the crank-shaft, one will obtain
three explosions in two revolutions. The manner in which
the explosion strokes occur and the manner they overlap
strokes in the other cylinder is shown at A. Assuming
that the cylinders fire in the following order, first No. 1,
then No. 2, and last No. 3, we will see that while cylinder
No. 1, represented by the outer circle, is on the power
stroke, cylinder No. 3 has completed the last two-thirds
of its exhaust stroke and has started on its intake stroke.
Cylinder No. 2, represented by the middle circle, during
this same period has completed its intake stroke and two-
thirds of its compression stroke. A study of the diagram
will show that there is an appreciable lapse of time be-
tween each explosion.

Three-cylinder engines are not used on aircraft at the
present time, though Bleriot's flight across the British
Channel was made with a three-cylinder Anzani motor.
It was not a conventional form, however. The three-cyl-
inder engine is practically obsolete at this time for any
purpose except "penguins" or school machines that are
incapable of flight and which are used in some French
training schools for aviators.

Four- and Six -Cylinder Engines

Firing Order 1,3,2

7
Three Cylinder, Cranks At 120 Degrees

Firing Order J. 2,4,3

Four Cylinder, Cranhs At 180 Degrees

First Revolution
78(T 180

Second Revolution
780 780

Fig. 23. Diagrams Demonstrating Clearly Advantages which Obtain when
Multiple-Cylinder Motors are Used as Power Plants.

88 Aviation Engines

FOUR- AND SIX-CYLINDER ENGINES

In the four-cylinder engine operation which is shown
at Fig. 23, B, it will be seen that the power strokes follow
each other without loss of time, and one cylinder begins
to fire and the piston moves down just as soon as the
member ahead of it has completed its power stroke. In
a four-cylinder motor, the crank-pins are placed at one
hundred and eighty degrees, or on the halves of the crank
circle. The crank-pins for cylinders No. 1 and No. 4 are
on the same plane, while those for cylinders No. 2 and
No. 3 also move in unison. The diagram describing se-
quence of operations in each cylinder is based on a firing
order of one, two, four, three. The outer circle, as in
previous instances, represents the cycle of operations in
cylinder one. The next one toward the center, cylinder
No. 2, the third circle represents the sequence of events
in cylinder No. 3, while the inner circle outlines the strokes
in cylinder four. The various cylinders are working as
follows :

1. 2. 3. 4.

Explosion Compression Exhaust Intake

Exhaust Explosion Intake Compression

Intake Exhaust Compression Explosion

Compression Intake Explosion Exhaust

It will be obvious that regardless of the method of
construction, or the number of cylinders employed, ex-
actly the same number of parts must be used in each
cylinder assembly and one can conveniently compare
any multiple-cylinder power plant as a series of single-
cylinder engines joined one behind the other and so
coupled that one will deliver power and produce useful
energy at the crank-shaft where the other leaves off.
The same fundamental laws governing the action of a
single cylinder obtain when a number are employed, and
the sequence of operation is the same in all members, ex-
cept that the necessary functions take place at different

Why Multiple Cylinder Forms- Are Best 89

times. If, for instance, all the cylinders of a four-cylin-
der motor were fired at the same time, one would obtain
the same effect as though a one-piston engine was used,
which had a piston displacement equal to that of the four
smaller members. As is the case with a single-cylinder
engine, the motor would be out of correct mechanical bal-
ance because all the connecting rods would be placed on
crank-pins that lie in the same plane. A very large fly-
wheel would be necessary to carry the piston through the
idle strokes, and large balance weights would be fitted to
the crank-shaft in an effort to compensate for the weight
of the four pistons, and thus reduce vibratory stresses
which obtain when parts are not in correct balance.

There would be no advantage gained by using four
cylinders in this manner, and there would be more loss of
heat and more power consumed in friction than in a one-
piston motor of the same capacity. This is the reason
that when four cylinders are used the arrangement of
crank-pins is always as shown at Fig. 23, B i.e., two
pistons are up, while the other two are at the bottom of
the stroke. With this construction, we have seen that it
is possible to string out the explosions so that there will
always be one cylinder applying power to the crank-shaft.
The explosions are spaced equally. The parts are in
correct mechanical balance because two pistons are on the
upstroke while the other two are descending. Care is
taken to have one set of moving members weigh exactly
the same as the other. With a four-cylinder engine one
has correct balance and continuous application of energy.
This insures a smoother running motor which has greater
efficiency than the simpler one-, two-, and three-cylinder
forms previously described. Eliminating the stresses
which would obtain if we had an unbalanced ftiechanism
and irregular power application makes for longer life.
Obviously a large number of relatively light explosions
will produce less wear and strain than would a lesser
number of powerful ones. As the parts can be built lighter
if the explosions are not heavy, the engine can be oper-

Aviation Engines

ated at higher rotative speeds than when large and cum-
bersome members are utilized. Four-cylinder engines
intended for aviation work have been built according to
the designs shown at Fig. 24, but these forms are un-
conventional and seldom if ever used.

The six-cylinder type of motor, the action of which is
shown at Fig. 23, C, is superior to the four-cylinder, inas-

Radial Cylinder
Arrangement

Two Sets of Opposed Cylinders

Fig. 24. Showing Three Possible Though Unconventional Arrangements of
Four-Cylinder Engines.

much as the power strokes overlap, and instead of having
two explosions each revolution we have three explosions.
The conventional crank-shaft arrangement in a six-cylinder
engine is just the same as though one used two three-
cylinder shafts fastened together, so pistons 1 and 6 are
on the same plane as are pistons 2 and 5. Pistons 3 and
4 also travel together. With the cranks arranged as out-
lined at Fig. 23, C, the firing order is one, five, three, six,
two, four. The manner in which the power strokes overlap
is clearly shown in the diagram. An interesting com-

Why Multiple Cylinder Forms Are Best 91

parison is also made in the diagrams at Fig. 25 and in the
upper corner of Fig. 23, C.

A rectangle is divided into four columns ; each of these
corresponds to one hundred and eighty degrees, or half a
revolution. Thus the first revolution of the crank-shaft
is represented by the first two columns, while the second
revolution is represented by the last two. Taking the por-

THE APPLICATION OF POWER IN THE SIX-CYLINDER MOTOR

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THE APPLICATION OF POWER IN THE FOUR-CYLINDER MOTOR

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THIS DIAGRAM REPRESENTS ONE "CYCLE" IN WHICH THE PISTON TRAVELS 20 INCHES
MOTQR _na REPRESENTS POWER I I REPRESENTS NO POWER

\ CYL
2 CYL.

4 CYL

6 CYL

Fig. 25. Diagrams Outlining Advantages of Multiple Cylinder Motors, and
Why They Deliver Power More Evenly Than Single Cylinder Types.

tion of the diagram which shows the power impulse in a
one-cylinder engine, we see that during the first revolution
there has been no power impulse. During the first half
of the second revolution, however, an explosion takes place
and a power impulse is obtained. The last portion of the
second revolution is devoted to- exhausting the burned
gases, so that there are three idle strokes and but one
power stroke. The effect when two cylinders are employed
is shown immediately below.

Aviation Engines

Here we have one explosion during the first half of the
first revolution in one cylinder and another during the first
half of the second revolution in the other cylinder. "With
a four-cylinder engine there is an explosion each half revo-
lution, while in a six-cylinder engine there is one and one-
half explosions during each half revolution. When six

Diagrams Show incj Duration of Eve nts
for a Four Stroke Cycle. Six Cylinder Engine

When Fxhaus* Valves open 45 early

and clofe 7" late, and Inlet

Valves open 12 late and

Fig, 4

No+e.-Read Figs. '3&4
from Centers Outward

1st Str 2nd Str 3rd Str 4th Str

1st Revolution
720:-0

ONE CYC LE

360'

2nd Revolution

Fig. 3

540*

Fig. 26. Diagrams Showing Duration of Events for a Four-Stroke Cycle,

Six-Cylinder Engine.

cylinders are used there is no lapse of time between power
impulses, as these overlap* and a continuous and smooth-
turning movement is imparted to the crank shaft. The
diagram shown at Fig. 26, prepared by E. P. Pulley, can
be studied to advantage in securing an idea of the coor-
dination of effort that takes place in an engine of the six-
cylinder type.

Actual Duration of Cycle Functions

ACTUAL DURATION OF DIFFERENT STROKES

In the diagrams previously presented the writer has
assumed, for the sake of simplicity, that each stroke takes
place during half of one revolution of the crank-shaft,

Inlet Value
Opens l 3 ^'Past
Center-Upper,

Exhaust Value
Closes 1^ Past
Center-Upper

Inlet Valve

Center-Lower

Exhaust Valve
Opens 7"Before
Center-Lower

Fig. 27. Diagram Showing Actual Duration of Different Strokes in Degrees.

which corresponds to a crank-pin travel of one hundred
and eighty degrees. The actual duration of these strokes
is somewhat different. For example, the inlet stroke is
usually a trifle more than a half revolution, and the exhaust
is always considerably more. The diagram showing the
comparative duration of the strokes is shown at Fig. 27.

94 Aviation Engines

The inlet valve opens ten degrees after the piston starts
to go down and remains open thirty degrees after the
piston has reached the bottom of its stroke. This means
that the suction stroke corresponds to a crank-pin travel
of two hundred degrees, while the compression stroke is
measured by a movement of but one hundred and fifty
degrees. It is common practice to open the exhaust valve
before the piston reaches the end of the power stroke so
that the actual duration of the power stroke is about one
hundred and forty degrees, while the exhaust stroke cor-
responds to a crank-pin travel of two hundred and twenty-
five degrees. In this diagram, which represents proper

Power 1 ^^g^g^^Exhaus

\\Compression \ Power <? ^H Exhaust

ompression

Lompressionm U Power 6
CompressionlMl UPower4^^f Exhaust

1
Revolutions

Fig. 28. Another Diagram to Facilitate Understanding Sequence of
Functions in Six-Cylinder Engine.

time for the valves to open arid close, the dimensions in
inches given are measured on the fly-wheel and apply only
to a certain automobile motor. If the fly-wheel were
smaller ten degrees would take up less than the dimensions
given, while if the fly-wheel was larger a greater space on
its circumference would represent the same crank-pin
travel. Aviation engines are timed by using a timing disc
attached to the crank-shaft as they are not provided with
fly-wheels. Obviously, the distance measured in inches
will depend upon the diameter of the disc, though the
number of degrees interval would not change.

EIGHT- AND TWELVE-CYLINDER V ENGINES

Those who have followed the development of the gaso-
line engine will recall the arguments that were made when
the six-cylinder motor was introduced at a time that the

Vee Engine Advantages

four-cylinder type was considered standard. The arrival
of the eight-cylinder has created similar futile discussion
of its practicability as this is so clearly established as to
be accepted without question. It has been a standard
power plant for aeroplanes for many years, early expo-
nents having been the Antoinette, the Woolsley, the
Kenault, the E. N. V. in Europe and the Curtiss in the
United States.

The reason the V type shown at Fig. 29, A is favored is
that the "all-in-line form" which is shown at Fig. 29, B is

Fig. 29. Types of Eight-Cylinder Engines Showing the Advantage of the
V Method of Cylinder Placing.

not practical for aircraft because of its length. Compared
to the standard four-cylinder engine it is nearly twice as
long and it required a much stronger and longer crank-
shaft. It will be evident that it could not be located to
advantage in the airplane fuselage. These undesirable
factors are eliminated in the V type eight-cylinder motor,
as it consists of two blocks of four cylinders each, so ar-
ranged that one set or block is at an angle of forty-five
degrees from the vertical center line of the motor, or at
an angle of ninety degrees with the other set. This
arrangement of cylinders produces a motor that is no

Aviation Engines

longer than a four-cylinder engine of half the power
would be.

Apparently there is considerable misconception as to
the advantage of the two extra cylinders of the eight as
compared with the six-cylinder. It should be borne in mind
that the multiplication in the number of cylinders noticed
since the early days of automobile development has not
been for solely increasing the power of the engine, but to
secure a more even turning movement, greater flexibility

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Comparative torque diagram* of four, elx and eight-cylinder motor*, showing Increaie In uniform ty with added cylinder!

Fig. 30. Curves Showing Torque of Various Engine Types Demonstrate
Graphically Marked Advantage of the Eight-Cylinder Type.

and to eliminate destructive vibration. The ideal internal
combustion motor is the one having the most uniform turn-
ing movement with the least mechanical friction loss.
Study of the torque outlines or plotted graphics shown
at Figs. 25 and 30 will show how multiplication of cylinders
will produce steady power delivery due to overlapping
impulses. The most practical form would be that which
more nearly conforms to the steady running produced by
a steam turbine or electric motor. The advocates of the
eight-cylinder engine bring up the item of uniform torque

Vee Engine Advantages

as one of the most important advantages of the eight-
cylinder design. A number of torque diagrams are shown
at Fig. 30. While these appear to be deeply technical,
they may be very easily followed when their purpose is
explained. At the top is shown the torque diagram of a
single-cylinder motor of the four-cycle type. The high

Fig. 31. Diagrams Showing How Increasing Number of Cylinders Makes
for More Uniform Power Application.

point in the line represents the period of greatest torque
or power generation, and it will be evident that this occurs
early in the first revolution of the crank-shaft. Below this
diagram is shown a similar curve except that it is pro-
duced by a four-cylinder engine. Inspection will show that
the turning moment is much more uniform than in the

98 Aviation Engines

single cylinder; similarly, the six-cylinder diagram is an
improvement over the four, and the eight-cylinder diagram
is an improvement over the six-cylinder.

The reason that practically continuous torque is ob-
tained in an eight-cylinder engine is that one cylinder fires
every ninety degrees of crank-shaft rotation, and as each
impulse lasts nearly seventy-five per cent, of the stroke,
one can easily appreciate that an engine that will give four
explosions per revolution of the crank-shaft will run more
uniformly than one that gives but three explosions per
revolution, as the six-cylinder does, and will be twice as
smooth running as a four-cylinder, in which but two explo-
sions occur per revolution of the crank-shaft. The com-
parison is so clearly shown in graphical diagrams and in
Fig. 31 that further description is unnecessary.

Any eight-cylinder engine may be considered a "twin-
four," twelve-cylinder engines may be considered "twin

sixes/

The only points in which an eight-cylinder motor dif-
fers from a four-cylinder is in the arrangement of the
connecting rod, as in many designs it is necessary to have
two rods working from the same crank-pin. This difficulty
is easily overcome in some designs by staggering the cylin-
ders and having the two connecting rod big ends of con-
ventional form side by side on a common crank-pin. In
other designs one rod is a forked form and works on the
outside of a rod of the regular pattern. Still another
method is to have a boss just above the main bearing on
one connecting rod to which the lower portion of the con-
necting rod in the opposite cylinder is hinged. As the
eight-cylinder engine may actually be made lighter than
the six-cylinder of equal power, it is possible to use smaller
reciprocating parts, such as pistons, connecting rods and
valve gear, and obtain higher engine speed with practically
no vibration. The firing order in nearly every case is the
same as in a four-cylinder except that the explosions occur
alternately in each set of cylinders. The firing order of
an eight-cylinder motor is apt to be confusing to the

100

Aviation Engines

motorist, especially if one considers that there are eight
possible sequences. The majority of engineers favor the
alternate firing from side to side. Firing orders will be
considered in proper sequence.

The demand of aircraft designers for more power has
stimulated designers to work out twelve-cylinder motors.

ft, I

Fig. 33. The Hall-Scott Four-Cylinder 100 Horse-Power Aviation Motor.

These are high-speed motors incorporating all recent fea-
tures of design in securing light reciprocating parts, large
valve openings, etc. The twelve-cylinder motor .incorpor-
ates the best features of high-speed motor design and there
is no need at this time to discuss further the pros and cons
of the twelve-cylinder versus the eight or six, because it
is conceded by all that there is the same degree of steady
power application in the twelve over the eight as there
would be in the eight over the six. The question resolves

Propeller D
Reduction

Fig. 34. Two Views of the Duesenberg Sixteen Valve Four-Cylinder
Aviation Motor.
101

102 . Aviation Engines

itself into ]ia\ixig a motor of high power that will run with
, Epnmimn;vibr.atiofi and that produces smooth action. This
is well shoxvn by diagrams at Fig. 31. It should be re-
membered that if an eight-cylinder engine will give four
explosions per revolution of the fly-wheel, a twelve-cylinder
type will give six explosions per revolution, and instead
of the impulses coming 90 degrees crank travel apart, as
in the case of the eight-cylinder, these will come but 60

Overhead Cam Shaft

-Valves
Cylinders

'Starting
Crank

Oil Sump

Engine Base

Fig. 35. The Hall-Scott Six-Cylinder Aviation Engine.

degrees of crank travel apart in the case of the twelve-
cylinder. For this reason, the cylinders of a twelve are
usually separated by 60 degrees while the eight has the
blocks spaced 90 degrees apart. The comparison can be
easily made hy comparing the sectional views of Vee
engines at Fig. 32. When one realizes that the actual
duration of the power stroke is considerably greater than
120 degrees crank travel, it will be apparent that the
overlapping of explosions must deliver a very uniform
application of power. Vee engines have been devised

Radial Cylinder Arrangements

103

having the cylinders spaced but 45 degrees apart, but the
explosions cannot be timed at equal intervals as when 90
degrees separate the cylinder center lines.

RADIAL CYLINDER ARRANGEMENTS

"While the fixed cylinder forms of engines, having the
cylinders in tandem in the four- and six-cylinder models
as shown at Figs. 33 to 35 inclusive and the eight-cylinder
V types as outlined at Figs. 36 and 37 have been generally
used and are most in favor at the present time, other forms
of motors having unconventional cylinder arrangements
have been devised, though most of these are practically

View of Power Delivery End

Fig. 36. The Curtiss Eight-Cylinder, 200. Horse-Power Aviation Engine.

102

Aviation Engines

itself into lia\ing a motor of high power that will run with
p^minmiji^vibr.atioil and that produces smooth action. This
is well shcnvii by diagrams at Fig. 31. It should be re-
membered that if an eight-cylinder engine will give four
explosions per revolution of the fly-wheel, a twelve-cylinder
type will give six explosions per revolution, and instead
of the impulses coming 90 degrees crank travel apart, as
in the case of the eight-cylinder, these will come but 60

Overhead Cam Shaft

Magneto,

Water
Pump

Oil Sump

Engine Base

Fig. 35. The Hall-Scott Six-Cylinder Aviation Engine.

Radial Cylinder Arrangements

103

having the cylinders spaced but 45 degrees apart, but the
explosions cannot be timed at equal intervals as when 90
degrees separate the cylinder center lines.

RADIAL, CYLINDER ARRANGEMENTS

While the fixed cylinder forms of engines, having the
cylinders in tandem in the four- and six-cylinder models
as shown at Figs. 33 to 35 inclusive and the eight-cylinder
V types as outlined at Figs. 36 and 37 have been generally
used and are most in favor at the present time, other forms
of motors having unconventional cylinder arrangements
have been devised, though most of these are practically

View of Power Delivery En;

Fig. 36. The Curtiss Eight-Cylinder, 200. Horse-Power Aviation Engine.

104 Aviation Engines

obsolete. While many methods of decreasing weight and
increasing mechanical efficiency of a motor are known to
designers, one of the first to be applied to the construction
of aeronautical power plants was an endeavor to group
the components, which in themselves were not extremely
light, into a form that would be considerably lighter than
the conventional design. As an example, we may consider
those multiple-cylinder forms in which the cylinders are

Valve Rockers Intake Pipes

/
A An **. * A A .//

Reduction
Gear Case

Propeller
Flange

Carburetor

Fig. 37. The Sturtevant Eight- Cylinder, High Speed Aviation Motor.

disposed around a short crank-case, either radiating from
a common center as at Fig. 38 or of the fan shape shown
*at Fig. 39. This makes it possible to use a crank-case but
slightly larger than that needed for one or two cylinders
and it also permits of a corresponding decrease in length
of the crank-shaft. The weight of the engine is lessened
because of the reduction in crank-shaft and crank-case
weight and the elimination of a number of intermediate
bearings and their supporting webs which would be neces-
sary with the usual tandem construction. While there are
six power impulses to every two revolutions of the crank-

Radial Cylinder Arrangements

105

shaft, in the six-cylinder engine, they are not evenly spaced
as is possible with the conventional arrangement.

In the Anzani form, which is shown at Fig. 38, the crank-
case is stationary and a revolving crank-shaft is employed
as in conventional construction. The cylinders are five

Fig. 38. Anzani 40-50 Horse-Power Five-Cylinder Air Cooled Engine.

in number and the engine develops 40 to 50 H. P. with a
weight of 72 kilograms or 158.4 Ibs. The cylinders are of
the usual air-cooled form having cooling flanges only part
of the way down the cylinder. By using five cylinders it
is possible to have the power impulses come regularly,
they coming 145 crank-shaft travel apart, the crank-shaft
making two turns to every five explosions. The balance
is good and power output regular. The valves are

106

Aviation Engines

placed directly in the cylinder head and are operated by
a common pushrod. Attention is directed to the novel
method of installing the carburetor which supplies the mix-
ture to the engine base from which inlet pipes radiate to
the various cylinders. This engine is used on French
school machines.

In the form shown at Fig. 39 six cylinders are used,
all being placed above the crank-shaft center line. This

Fig. 39. Unconventional Six-Cylinder Aircraft Motor of Masson Design.

engine is also of the air-cooled form and develops 50 H. P.
and weighs 105 kilograms, or 231 Ibs. The carburetor is
connected to a manifold casting attached to the engine base
from which the induction pipes radiate to the various
cylinders. The propeller design and size relative to the
engine is clearly shown in this view. While flights have
been made with both of the engines described, this method
of construction is not generally followed and has been
almost entirely displaced abroad by the revolving motors
or by the more conventional eight-cylinder V engines.
Both of the engines shown were designed about eight years

Rotary Cylinder Engines 107

ago and would be entirely too small and weak for use in
modern airplanes intended for active duty.

ROTARY ENGINES

Rotary engines such as shown at Fig. 40 are generally
associated with the idea of light construction and it is

Fig. 40. The Gnome Fourteen-Cylinder Revolving Motor.

rather an interesting point that is often overlooked in
connection with the application of this idea to flight
motors, that the reason why rotary engines are popularly
supposed to be lighter than the others is because they form
their own fly-wheel, yet on aeroplanes, engines are seldom
fitted with a fly-wheel at all. As a matter of fact the

108 Aviation Engines

Gnome engine is not so light because it is a rotary motor,
and it is a rotary motor because the design that has
been adopted as that most conducive to lightness is
also most suited to an engine working in this way.
The cylinders could be fixed and crank-shaft revolve
without increasing the weight to any extent. There
are two prime factors governing the lightness of an
engine, one being the initial design, and the other the
quality of the materials employed. The consideration
of reducing weight by cutting away metal is a subsidi-
ary method that ought not to play a part in standard
practice, however useful it may be in special cases. In
the Gnome rotary engine the lightness is entirely due to
the initial design and to the materials employed in manu-
facture. Thus, in the first case, the engine is a radial
engine, and has its seven or nine cylinders spaced equally
around a crank-chamber that is no wider or rather longer
than would be required for any one of the cylinders.
This shortening of the crank-chamber not only effects
a considerable saving of weight on its own account, but
there is a corresponding saving in the shafts and other
members, the dimensions of which are governed by the
size of the crank-chamber. With regard to materials,
nothing but steel is used throughout, and most of the metal
is forged chrome nickel steel. The beautifully steady
running of the engine is largely due to the fact that there
are literally no reciprocating parts in the absolute sense,
the apparent reciprocation between the pistons and cylin-
ders being solely a relative reciprocation since both travel
in circular paths, that of the pistons, however, being
ele'ctric by one-half of the stroke length to that of the
cylinder.

While the Gnome engine has many advantages, on the
other hand the head resistance offered by a motor of this
type is considerable; there is a large waste of lubricating
oil due to the centrifugal force which tends to throw the
oil away from the cylinders; the gyroscopic effect of the
rotary motor is detrimental to the best working of the

Rotary Cylinder Engines 109

aeroplane, and moreover it requires about seven per cent,
of the total power developed by the motor to drive the
revolving cylinders around the shaft. Of necessity, the
compression of this type of motor is rather low, and an
additional disadvantage manifests itself in the fact that
there is as yet no satisfactory way of muffling the rotary
type of motor. The modern Gnome engine has been widely
copied in various European countries, but its design was
originated in America, the early Adams-Farwell engine
being the pioneer form. It has been made in seven- and
nine-cylinder types and forms of double these numbers.
The engine illustrated at Fig. 40 is a fourteen-cylinder
form. The simple engines have an odd number of cylin-
ders in order to secure evenly spaced explosions. In the
seven-cylinder, the impulses come 102.8 apart. In the
nine-cylinder form, the power strokes are spaced 80 apart.
The fourteen-cylinder engine is virtually two seven-cylin-
der types mounted together, the cranks being just the
same as in a double cylinder opposed motor, the explosions
coming 51.4 apart; while in the eighteen-cylinder model
the power impulses come every 40 cylinder travel. Other
rotary motors have been- devised, such as the Le Ehone
and the Clerget in France and several German copies of
these various types. The mechanical features of these
motors will be fully considered later.

CHAPTER V

Properties of Liquid Fuels Distillates of Crude Petroleum Principles
of Carburetion Outlined Air Needed to Buin Gasoline What
a Carburetor Should Do Liquid Fuel Storage and Supply
Vacuum Fuel Feed Early Vaporizer Forms Development of
Float Feed Carburetor Maybach's Early Design Concentric
Float and Jet Type Schebler Carburetor Claudel Carburetor
Stewart Metering Pin Type Multiple Nozzle Vaporizers Two-
Stage Carburetor Master Multiple Jet Type Compound Nozzle
Zenith Carburetor Utility of Gasoline Strainers Intake Manifold
Design and Construction Compensating for Various Atmospheric
Conditions How High Altitude Affects Power The Diesel Sys-
tem Notes on Carburetor Installation Notes on Carburetor Ad-
justment.

THERE is no appliance that has more material value
upon the efficiency of the internal combustion motor than
the carburetor or vaporizer which supplies the explosive
gas to the cylinders. It is only in recent years that en-
gineers have realized the importance of using carburetors
that are efficient and that are so strongly and simply made
that there will be little liability of derangement. As the
power obtained from the gas-engine depends upon the
combustion of fuel in the cylinders, it is evident that if
the gas supplied does not have the proper proportions of
elements to insure rapid combustion the efficiency of the
engine will be low. When a gas engine is used as a sta-
tionary installation it is possible to use ordinary illuminat-
ing or natural gas for fuel, but when this prime mover is
applied to automobiles or airplanes it is evident that con-
siderable difficulty would be experienced in carrying enough
compressed coal gas to supply the engine for even a very
short trip. Eortunately, the development of the internal-
combustion motor was not delayed by the lack of suitable
fuel.

Engineers \tere familiar with the properties of certain

Distillates of Crude Petroleum 111

liquids which gave off vapors that could be mixed with air
to form an explosive gas which burned very well in the
engine cylinders. A very small quantity of such liquids
would suffice for a very satisfactory period of operation.
The problem to be solved before these liquids could be
applied in a practical manner was to evolve suitable ap-
paratus for vaporizing them without waste. Among the
liquids that can be combined with air and burned, gasoline
is the most volatile and is the fuel utilized by internal-
combustion engines.

The widely increasing scope of usefulness of the in-
ternal-combustion motor has made it imperative that other
fuels be applied in some instances because the supply of
gasoline may in time become inadequate to supply the
demand. In fact, abroad this fuel sells for fifty to two*
hundred per cent, more than it does in America because
most of the gasoline used must be imported from this
country or Russia. Because of this foreign engineers have
experimented widely with other substances, such as alco-
hol, benzol, and kerosene, but more to determine if they
can be used to advantage in motor cars than in airplane
engines.

DISTILLATES OF CRUDE PETROLEUM

Crude petroleum is found in small quantities in almost
all parts of the world, but a large portion of that pro-
duced commercially is derived from American wells. The
petroleum obtained in this country yields more of the
volatile products than those of foreign production, and for
that reason the demand for it is greater. The oil fields
of this country are found in Pennsylvania, Indiana, and
Ohio, and the crude petroleum is usually in association
with natural gas. This mineral oil is an agent from which
many compounds and products are derived, and the prod-
ucts will vary from heavy sludges, such as asphalt, to
the lighter and more volatile components, some of which
will evaporate very easily at ordinary temperatures.

The compounds derived from crude petroleum are com-

112 Aviation Engines

posed principally of hydrogen and carbon and are termed
"Hydrocarbons." In the crude product one finds many
impurities, such as free carbon, sulphur, and various
earthy elements. Before the oil can be utilized it must be
subjected to a process of purifying which is known as
refining, and it is during this process, which is one of
destructive distillation, that the various liquids are sepa-
rated. The oil was formerly broken up into three main
.groups of products as follows : Highly volatile, naphtha,
benzine, gasoline, eight to ten per cent. Light oils, such
as kerosene and light lubricating oils seventy to eighty
per cent. Heavy oils or residuum five to nine per cent.
From the foregoing it will be seen that the available sup-
ply of gasoline is determined largely by the demand exist-
ing for the light oils forming the larger part of the
products derived from crude petroleum. New processes
have been recently discovered by which the lighter oils,
such as kerosene, are reduced in proportion and that of
gasoline increased, though the resulting liquid is neither
the high grade, volatile gasoline known in the early days
of motoring nor the low grade kerosene.

PRINCIPLES OF CARBURETION OUTLINED

The process of carburetion is combining the volatile
vapors which evaporate from the hydrocarbon liquids with
certain proportions of air to form an inflammable gas.
The quantities of air needed vary with different liquids
and some mixtures burn quicker than do other combina-
tions of air and vapor. Combustion is simply burning and
it may be rapid, moderate or slow. Mixtures of gasoline
and air burn quickly, in fact the combustion is so rapid
that it is almost instantaneous and we obtain what is
commonly termed an "explosion." Therefore the ex-
plosion of gas in the automobile engine cylinder which
produces the power is really a combination of chemical
elements which produce heat and an increase in the vol-
ume of the gas because of the increase in temperature.

If the gasoline mixture is not properly proportioned

Air Needed to Burn Gasoline 113

the rate of burning will vary, and if the mixture is either
too rich or too weak the power of the explosion is reduced
and the amount of power applied to the piston is de-
creased proportionately. In determining the proper pro-
portions of gasoline and air, one must take the chemical
composition of gasoline into account. The ordinary liquid
used for fuel is said to contain about eight-four per cent,
carbon and sixteen per cent, hydrogen. Air is composed
of oxygen and nitrogen and the former has a great affinity,
or combining power, with the two constituents of hydro-
carbon liquids. Therefore, what we call an explosion is
merely an indication that oxygen in the air has combined
with the carbon and hydrogen of the gasoline.

AIR NEEDED TO BURN GASOLINE

In figuring the proper volume of air to mix with a
given quantity of fuel, one takes into account the fact that
one pound of hydrogen requires eight pounds of oxygen
to burn it, and one pound of carbon needs two and one-
third pounds of oxygen to insure its combustion. Air is
composed of one part of oxygen to three and one-half por-
tions of nitrogen by weight. Therefore for each pound of
oxygen one needs to burn hydrogen or carbon four and
one-half pounds of air must be allowed. To insure com-
bustion of one pound of gasoline which is composed of
hydrogen and carbon we must furnish about ten pounds
of air to burn the carbon and about six pounds of air to
insure combustion of hydrogen, the other component of
gasoline. This means that to burn one pound of gasoline
one must provide about sixteen pounds of air.

While one does not usually consider air as having much
weight, at a temperature of sixty-two degrees Fahrenheit
about fourteen cubic feet of air will weigh a pound, and
to burn a pound of gasoline one would require about two
hundred cubic feet of air. This amount will provide for
combustion theoretically, but it is common practice to
allow twice this amount because the element nitrogen,
which is the main constituent of air, is an inert gas and

114 Aviation Engines

instead of aiding combustion it acts as a deterrent of

burning. In order to be explosive, gasoline vapor must
be combined with definite quantities of air. Mixtures that
are rich in gasoline ignite quicker than those which have
more air, but these are only suitable when starting or
when running slowly, as a rich mixture ignites much
quicker than a weak mixture. The richer mixture of
gasoline and air not only burns quicker but produces the
most heat and the most effective pressure in pounds per
square inch of piston top area.

The amount of compression of the charge before igni-
tion also has material bearing on the force of the explo-
sion. The higher the degree of compression the greater
the force exerted by the rapid combustion of the gas. It
may be stated that as a general thing the maximum ex-
plosive pressure is somewhat more than four times the
compression pressure prior to ignition. A charge com-
pressed to sixty pounds will have a maximum of approxi-
mately two hundred and forty pounds; compacted to
eighty pounds it will produce a pressure of about three
hundred pounds on each square inch of piston area at
the beginning of the power stroke. Mixtures varying
from one part of gasoline vapor to four of air to others
having one part of gasoline vapor to thirteen of air can
be ignited, but the best results are obtained when the
proportions are one to five or one to seven, as this mix-
ture is said to be the one that will produce the high-
est temperature, the quickest explosion, and the most
pressure.

WHAT A CAEBUKETOR SHOULD DO

While it is apparent that the chief function of a car-
bureting device is to mix hydrocarbon vapors with air to
secure mixtures that will burn, there are a number of fac-
tors which must be considered before describing the prin-
ciples of vaporizing devices. Almost any device which
permits a current of air to pass over or through a vola-
tile liquid will produce a gas which will explode when

What a Carburetor Should Do

115

116 Aviation Engines

compressed and ignited in the motor cylinder. Modern
carburetors are not only called upon to supply certain
quantities of gas, but these must deliver a mixture to the
cylinders that is accurately proportioned and which will
be of proper composition at all engine speeds.

Flexible control of the engine is sought by varying the
engine speed by regulating the supply of gas to the cylin-
ders. The power plant should run from its lowest to its
highest speed without any irregularity in torque, i.e., the
acceleration should be gradual rather than spasmodic. As
the degree of compression will vary in value with the
amount of throttle opening, the conditions necessary to
obtain maximum power differ with varying engine speeds.
When the throttle is barely opened the engine speed is
low and the gas must be richer in fuel than when the
throttle is wide open and the engine speed high.

"When an engine is turning over slowly the compression
has low value and the conditions are not so favorable to
rapid combustion as when the compression is high. At
high engine speeds the gas velocity through the intake
piping is higher than at low speeds, 'and regular engine
action is not so apt to be disturbed by condensation of
liquid fuel in the manifold due to excessively rich mixture
or a superabundance of liquid in the stream of carbureted
air.

LIQUID FUEL, STORAGE AND SUPPLY

The problem of gasoline storage and method of supply-
ing the carburetor is one that is determined solely by
design of the airplane. While the object of designers
should be to supply the fuel to the carburetor by as 'simple
means as possible the fuel supply system of some airplanes
is quite complex. The first point to consider is the loca-
tion of the gasoline tank. This depends upon the amount
of fuel needed and the space available in the fuselage.

A very simple and compact fuel supply system is shown
at Fig. 41. In this instance the fuel container is placed
immediately back of the engine cylinder. The carburetor

Liquid Fuel Storage and Supply 117

which is carried as indicated is joined to the tank by a
short piece of copper or flexible rubber tubing. This is
the simplest possible form of fuel supply system and one
used on a number of excellent airplanes.

As the sizes of engines increase and the power plant
fuel consumption augments it is necessary to use more
fuel, and to obtain a satisfactory flying radius without
frequent landings for filling the fuel tank it is necessary
to supply large containers.

When a very powerful power plant is fitted, as on
battle planes of high capacity, it is necessary to carry
large quantities of gasoline. In order to use a tank of
sufficiently large capacity it may be necessary to carry it
lower than the carburetor. When installed in this manner
it is necessary to force fuel out of the tank by air pres-
sure or to pump it with a vacuum tank because the gasoline
tank is lower than the carburetor it supplies and the gaso-
line cannot flow by gravity as in the simpler systems.
While the pressure and gravity feed systems are generally
used in airplanes, it may be well to describe the vacuum
lift system which has been widely applied to motor cars
and which may have some use in connection with airplanes
as these machines are developed.

STEWART VACUUM FUEL FEED

One of the marked tendencies has been the adoption
of a vacuum fuel feed system to draw the gasoline from
tanks placed lower than the carburetor instead of using
either exhaust gas or air pressure to achieve this end. The
device generally fitted is the Stewart vacuum feed tank
which is clearly shown in section at Fig. 42. In this sys-
tem the suction of a motor is employed to draw gasoline
from the main fuel tank to the auxiliary tank incorporated
in the device and from this tank the liquid flows to the
carburetor. It is claimed that all the advantages of the
pressure system are obtained with very little more com-
plication than is found on the ordinary gravity feed. The
mechanism is all contained in the cylindrical tank shown,

118

Aviation Engines

which may be mounted either on the front of the dash or
on the side of the engine as shown.

The tank is divided into two chambers, the upper one
being the filling chamber and the lower one the emptying

Atmospheric Valve
Suction Valve ^
,'Fr0m Gasoline Tank

'Suction Pipe

Fig. 42. The Stewart Vacuum Fuel Feed Tank.

chamber. The former, which is at the top of the device,
contains the float valve, as well as the pipes running to
the main fuel container and to the intake manifold. The
lower chamber is used to supply the carburetor with gaso-
line and is under atmospheric pressure at all times, so the
flow of fuel from it is by means of gravity only. Since

Stewart Vacuum Feed System 119

this chamber is located somewhat above the carburetor,
there must always be free flow of fuel. Atmospheric pres-
sure is maintained by the pipes A and B, the latter open-
ing into the air. In order that the fuel will be sucked
from a main tank to the upper chamber, the suction valve
must be opened and the atmospheric valve closed. Under
these conditions the float is at the bottom and the suction
at the intake manifold produces a vacuum in the tank
which draws the gasoline from the main tank to the upper
chamber. When the upper chamber is filled at the proper
height the float rises to the top, this closing the suction
valve and opening the atmospheric valve. As the suction
is now cut off, the lower chamber is filled by gravity owing
to there being atmospheric pressure in both upper and
lower chambers. A flap valve is provided between the
two chambers to prevent the gasoline in the lower one
from being sucked back into the upper one. The atmos-
pheric and suction valves are controlled by the levers C
and D, both of which are pivoted at E, their outer ends
being connected by two coil springs. It is seen that the
arrangement of these two springs is such that the float
must be held at the extremity of its movement, and that
it cannot assume an intermediate position.

This intermittent action is required to insure that the
upper part of the tank may be under atmospheric pressure
part of the time for the gasoline to flow to the lower cham-
ber. When the level of gasoline drops to a certain point,
the float falls, thus/ opening the suction valve and closing
the atmospheric valve. The suction of the motor then
causes a flow of fuel from the main container. As soon
as the level rises to the proper height the float returns to
its upper position. It takes about two seconds for the
chamber to become full enough to raise the float, as but
.05 gallon is transferred at a time. The pipe running from
the bottom of the lower chamber to the carburetor extends
up a ways, so that there is but little chance of dirt or water
being carried to the float chamber.

If the engine is allowed to stand long enough so that the

120 Aviation Engines

tank becomes empty, it will be replenished after the motor
has been cranked over four or five times with the throttle
closed. The installation of the Stewart Vacuum- Gravity
System is very simple. The suction pipe is tapped into
the manifold at a point as near, the cylinders as possible,
while the fuel pipe is inserted into the gasoline tank and
runs to the bottom of that member. There is a screen at
the end of the fuel pipe to prevent any trouble due to de-
posits of sediment in the main container. As the fuel is
sucked from the gasoline tank a small vent must be made
in the tank filler cap so that the pressure in the main tank
will always be that of the atmosphere.

EARLY VAPORIZER FORMS

The early types of carbureting devices were very crude
and cumbersome, and the mixture of gasoline vapor and
air was accomplished in three ways. The air stream was
passed over the surface of the liquid itself, through loosely
placed absorbent material saturated with liquid, or directly
through the fuel. The first type is known as the surface
carburetor and is now practically obsolete. The second
form is called the "wick" carburetor because the air
stream was passed over or through saturated wicking. The
third form was known as a "bubbling" carburetor. While
these primitive forms gave fairly good results with the
early slow-speed engines and the high grade, or very
volatile, gasoline which was first used for fuel, they would
be entirely unsuitable for present forms of engines be-
cause they would not carburate the lower grades of gaso-
line which are used to-day, and would not supply the
modern high-speed engines with gas of the proper consis-
tency fast enough even if they did not have to use very
volatile gasoline. The form of carburetor used at the
present time operates on a different principle. These
devices are known as "spraying carburetors." The fuel
is reduced to a spray by the suction effect of the entering
air stream drawing it through a fine opening.

The advantage of this construction is that a more

Early Vaporizer Form*

121

thorough amalgamation of the gasoline and air particles
is obtained. With the earlier types previously considered
the air would combine with only the more volatile elements,
leaving the heavier constituents in the tank. As the fuel
became stale it was difficult to vaporize it, and it had to

Jump Value
Adjustment

Mixture
Passage

Gasoline Adjustment

Fig. 43. Marine-Type Mixing Valve, by which Gasoline is Sprayed into Air
Stream Through Small Opening in Air-Valve Seat.

be drained off and fresh fuel provided before the proper
mixture would be produced. It will be evident that when
the fuel is sprayed into the air stream, all the fuel will be
used up and the heavier portions of the gasoline will be
taken into the cylinder and vaporized just as well as the
more volatile vapors.

The simplest form of spray carburetor is that shown
at Fig. 43. In this the gasoline opening through which

122 Aviation Engines

the fuel is sprayed into the entering air stream is closed
by the spring-controlled mushroom valve which regulates
the main air opening as well. When the engine draws in
a charge of air it unseats the valve and at the same time
the air flowing around it is saturated with gasoline par-
ticles through the gasoline opening. The mixture thus
formed goes to the engine through the mixture passage,
Two methods of varying the fuel proportions are provided.
One of these consists of a needle valve to regulate the
amount of gasoline, the other is a knurled screw which
controls the amount of air by limiting the lift of the
jump valve.

DEVELOPMENT OF FLOAT-FEED CARBURETOR

The modern form of spraying carburetor is provided
with two chambers, one a mixing chamber through which
the air stream passes and mixes with a gasoline spray,
the other a float chamber in which a constant level of fuel
is maintained by simple mechanism. A jet or standpipe
is used in the mixing chamber to spray the fuel through
and the object of the float is to maintain the fuel level
to such a point that it will not overflow the jet when the
motor is not drawing in a charge of gas. With the simple
forms of generator valve in which the gasoline opening is
controlled by the air valve, a leak anywhere in either
valve or valve seat will allow the gasoline to flow continu-
ously whether the engine is drawing in a charge or not.
The liquid fuel collects around the air opening, and when
the engine inspires a charge it is saturated with gasoline
globules and is excessively rich. With a float-feed con-
struction, which maintains a constant level of gasoline at
the right height in the standpipe, liquid fuel will only be
supplied when drawn out of the jet by the suction effect
of the entering air stream.

MAYBACH'S EARLY DESIGN

The first form of spraying carburetor ever applied
successfully was evolved by Maybach for use on one of the

Maybaclis Early Design

123

124 Aviation Engines

earliest Daimler engines. The general principles of opera-
tion of this pioneer float-feed carburetor are shown at
Fig. 44, A. The mixing chamber and valve chamber were
one and the standpipe or jet protruded into the mixing
chamber. It was connected to the float compartment by a
pipe. The fuel from the tank entered the top of the float
compartment and the opening was closed by a needle
valve carried on top of a hollow metal float. When the
level of gasoline in the float chamber was lowered the
float would fall and the needle valve uncover the opening.
This would permit the gasoline from the tank to flow into
the float chamber, and as the chamber filled the float would
rise until the proper level had been reached, under which
conditions the float would shut off the gasoline opening.
On every suction stroke of the engine the inlet valve, which
was an automatic type, would leave its seat and a stream
of air would be drawn through the air opening and around
the standpipe or jet. This would cause the gasoline to
spray out of the tube and mix with the entering air stream.
The form shown at B ivas a modification of Maybach's
simple device and was first used on the Phoenix-Daimler
engines. Several improvements are noted in this device.
First, the carburetor was made one unit by casting the
float and mixing chambers together instead of making them
separate and joining them by a pipe, as shown at A. The
float construction was improved and the gasoline shut-off
valve was operated through leverage instead of being di-
rectly fastened to the float. The spray nozzle was sur-
rounded by a choke tube which concentrated the air stream
around it and made for more rapid air flow at low engine
speeds. A conical piece was placed over the jet to break
up the entering spray into a mist and insure more intimate
admixture of air and gasoline. The air opening was
provided with an air cone which had a shutter controlling
the opening so that the amount of air entering could be
regulated and thus vary the mixture proportions within
certain limits.

Schebler Carburetor Construction 125

CONCENTRIC FLOAT AND JET TYPE

The form shown at B has been further improved, and
the type shown at C is representative of modern single
jet practice. In this the float chamber and mixing chamber
are concentric. A balanced float mechanism which insures
steadiness of feed is used, the gasoline jet or standpipe
is provided with a needle valve to vary the amount of
gasoline supplied the mixture and two air openings are
provided. The main air port is at the bottom of the
vaporizer, while an auxiliary air inlet is provided at the
side of the mixing chamber. There are two methods of
controlling the mixture proportions in this form of car-
buretor. One may regulate the gasoline needle or adjust
the auxiliary air valve.

SCHEBLER CARBURETOR

A Schebler carburetor, which has been used on some
airplane engines, is shown in Fig. 45. It will be noticed
that a metering pin or needle, valve opens the jet when
the air valve opens. The long arm of a leverage is con-
nected to the air valve, while the short arm is connected
to the needle, the reduction in leverage being such that
the needle valve is made to travel much less than the air
valve. For setting the amount of fuel passed or the size
of the jet orifice when running with the air valve closed,
there is a screw which raises or lowers the fulcrum of
the lever and there is also a dash control having the same
effect by pushing down the fulcrum against a small spring.
A long extension is given to the venturi tube which* is very
narrow around the jet orifices, which are horizontal and
shown at A in the drawing. Fuel enters the float chamber
through the union M, and the spring P holds the metering
pin upward against the restraining action of the lever.
The air valve may be set by an easily adjustable knurled
screw shown in the drawing, and fluttering of the valve is
prevented by the piston dash pot carried in a chamber
above the valve into which the valve stem projects. The

126

Aviation Engines

Claudel Carburetor

127

primary air enters beneath the jet passage and there is
a small throttle in the intake to increase the speed of air
flow for starting purposes. The carburetor is adapted for
the use of a hot-air connection to the stove around the
exhaust pipe and it is recommended that such a fitting be
supplied. The lever which controls the supply of air

Float Yalve.

,- Mixture Outlet

,., -Throttle

Float

Bowl ->

^-Mixing

Chamber.

Compound
Spray Nozzle

filter

Screen'

Fig. 46. The Claudel Carburetor

through the primary air intake is so arranged that if
desired it can be connected with a linkage on the dash
or control column by means of a flexible wire.

THE CLAUDEL (FRENCH) CARBURETOR

This carburetor is of extremely simple construction,
because it has no supplementary or auxiliary air valve
and no moving parts except the throttle controlling the
gas flow. The construction is already shown in Fig. 46.

128 Aviation Engines

The spray jet is eccentric with a surrounding sleeve or
tube in which there are two series of small orifices, one
at the top and the other near the bottom. The former
are about level with the spray jet opening. The sleeve
surrounding the nozzle 'is closed at the top. The air,
passing the upper holes in the sleeve, produces a vacuum
in the sleeve, thereby drawing air in through the bottom
holes. It is this moving interior column of air that con-
trols the flow of gasoline from the nozzle. Owing to the
friction of the small passages, the speed of air flow through
the sleeve does not increase as fast as the speed of air
flow outside the sleeve, hence there is a tendency for the
mixture to remain constant. The throttle of this carbure-
tor is of the barrel type, and the top of the spray nozzle
and its surrounding sleeve are located inside the throttle.

STEWART METERING PIN CARBURETOR

The carburetor shown at Fig. 47 is a metering type in
which the vacuum at the jet is controlled by the weight
of the metering valve surrounding the upright metering
pin. The only moving part is the metering valve, which
rises and falls with the changes in vacuum. The air
chamber surrounds the metering valve, and there is a mix-
ing chamber above. As the valve is drawn up the gasoline
passage is enlarged on account of the predetermined taper
on the metering pin, and the air passage also is increased
proportionately, giving the correct mixture. A dashpot
at the bottom of the valve checks flutter. In idling the
valve rests on its seat, practically closing the air and giv-
ing the necessary idling mixture. A passage through the
valve acts as an aspirating tube. "When the valve is closed
altogether the primary air passes through ducts in the
valve itself, giving the proper amount for idling. The
one adjustment consists in raising or lowering the tapered
metering pin, increasing or decreasing the supply of
gasoline. Dash control is supplied. This pulls down the
metering pin, increasing the gasoline flow. The duplex
type for eight- and twelve-cylinder motors is the same in

Multiple Nozzle Vaporizers

129

principle as model 25, but it is a double carburetor syn-
chronized as to throttle movements, adjustments, etc. The
duplex for aeronautical motors is made of cast aluminum
alloy.

MULTIPLE NOZZLE VAPORIZERS

To secure properly proportioned mixtures some car-
buretor designers have evolved forms in which two or
more nozzles are used in a common mixing chamber. The
usual construction is to use two, one having a small open-
ing and placed in a small air tube and used only for low

Th rattle -

Automatic
Metering Valve ...

Aspirating -
Tube

Dash Pot~"

Tapered
Metering Pin--

Primary
Air Passages

Flared End of
Aspirating Tube.

Float
Chamber

Inlet Needle Valve
" -Gasoline Strainer

Primary
Air Passages

Mixing Chamber

Thforf/e.

'Automatic
.Metering Valve

Automatic
Metering Valve

\-AirChamber

-- Gasoline

Aspirant Tube-''
Dash Pot--'''

Tapered Tapered

Metering Metering Pin-

, Primary Air

Passage

^Gasoline
Strainer

'Gasoline Passage

Fig. 47. The Stewart Metering Pin Carburetor.

130 Aviation Engines

speeds, the other being placed in a larger air tube and
having a slightly augmented bore so that it is employed
on intermediate speeds. At high speeds both jets would
be used in series. Some multiple jet carburetors could
be considered as a series of these instruments, each one
being designed for certain conditions of engine action.
They would vary from small size just sufficient -to run
the engine at low speed to others having sufficient capacity
to furnish gas for the highest possible engine speed when
used in conjunction with the smaller members which have
been brought into service progressively as the engine speed
has been augmented. The multiple nozzle carburetor dif-
fers from that in which a single spray tube is used only
in the construction of the mixing chamber, as a common
float bowl i&an be used to supply all spray pipes. It is
common practice to bring the jets into action progres-
sively by some form of mechanical connection with the
throttle or by automatic valves.

The object of any multiple nozzle carburetor is to
secure greater flexibility and endeavor to supply mix-
tures of proper proportions at all speeds of the engine.
It should be stated, however, that while devices of this
nature lend themselves readily to practical application it
is more difficult to adjust them than the simpler forms
having but one nozzle. When a number of jets are used
the liability of clogging, up the carburetor is increased,
and if one or more of the nozzles is choked by a particle
of dirt or water the resulting mixture trouble is difficult
to detect. One of the nozzles may supply enough gasoline
to permit the engine to run well at certain speeds and yet
not be adequate to supply the proper amount of gas under
other conditions. In adjusting a multiple jet carburetor
in which the jets are provided with gasoline regulating
needles, it is customary to consider each nozzle as a dis-
tinct carburetor and to regulate it to secure the best motor
action at that throttle position which corresponds to the
conditions under which the jet is brought into service.
For instance, that supplied the primary mixing chamber

Ball and Ball Two-Stage Carburetor

131

should be regulated with the throttle partly closed, while
the auxiliary jet should be adjusted with the throttle fully
opened.

BALL AND BALL TWO-STAGE CARBURETOR

This is a two-stage vaporizing device, hot air being
used in the primary or initial stage of vaporization and
cold air in the supplementary stage. Eeferring to the
sectional illustration at Fig. 48, it will be seen that there

Fig. 48. The Ball and Ball Two-Stage Carburetor.

is a hot-air passage with a choke-valve; the primary ven-
turi appears at B ; J is its gasoline jet, and V is a spring-
loaded idling valve in a fixed air opening. These parts
constitute the primary system. In the secondary system
A is a cold-air passage, T a butterfly valve and J a gaso-
line jet discharging into the cold-air passage. This sys-
tem is brought into operation by opening the butterfly T.
A connection between the butterfly T and the throttle, not
shown, throws the butterfly wide open when the throttle
is not quite wide open; at all other times the butterfly

132 Aviation Engines

is held closed by a spring. The cylindrical chamber at
the right of the mixing chamber has an extension E of
reduced diameter connecting it with the intake manifold
through a passage D. A restricted opening connects the
float chamber with the cylindrical chamber so that the
gasoline level is the same in both. A loosely fitting plun-
ger P in the cylindrical chamber has an upward extension
into the small part of the chamber. is a small air
opening and M is a passage from the cylindrical chamber
to the mixing chamber. Air constantly passes through
this when the carburetor is in operation. The carburetor
is really two in one. The primary carburetor is made up
of a central jet in a venturi passage. The float chamber
is eccentric. In the air passage there is a fixed opening,
and additional air is taken in by the opening through
suction of a spring-opposed air valve. The second stage,
which comes into play as soon as the carburetor is called
upon for additional mixture above low medium speeds,
is made up of an independent air passage containing an-
other air valve. As the valve is opened this jet is un-
covered, and air is led past it. For easy starting an
extra passage leads from the float bowl passage to a point
above the throttle. All the suction falls upon this passage
when the throttle is closed. The passage contains a plun-
ger and acts as a pick-up device. When the vacuum in-
creases the plunger rises and shuts off the flow of gasoline
from the intake passage. As the throttle is opened the
vacuum in the intake passage is broken, and the plunger
falls, causing gasoline to gather above it. This is imme-
diately drawn through the pick-up passage and gives the
desired mixture for acceleration.

MASTER MULTIPLE-JET CARBURETOR

This carburetor, shown in detail in Figs. 49 and 50,
has been very popular in racing cars and aviation engines
because of exceptionally good pick-up qualities and its
thorough atomization of fuel. Its principle of operation
is the breaking up of the fuel by a series of jets, which

Master Multiple-Jet Carburetor

133

vary in number from fourteen to twenty-one, according
to the size of the carburetor. These are uncovered by
opening the throttle, which is curved a patented feature
to secure the correct progression of jets. The carbu-

S A E Standard Flan

Damper Operated by Control

Acts as Variable
Venturl Controlling Mixture.

14 to 19 Fine Holes
Where Fuel Comes
Out of Distributer
as Throttle is Opened

Air
Intake

Where Fuel Enters Distributer
First Being Thoroughly Filtered

-Normal Running

Starting
Position

Fig. 49. The Master Carburetor.

retor has an eccentric float chamber, from which the gas-
oline is led to the jet piece from which the jets stand up
in a row. The tops of these jets are closed until the
throttle is opened far enough to pass them, which it does
progressively. The air opening is at the bottom, and the
throttle opening is such that a modified venturi is formed.

134

Aviation Engines

The throttle is carried in a cylindrical barrel with the jets
placed below it, and the passage from the barrel to the
intake is arranged so that, there is no interruption in the
flow. For easy starting a dash-controlled shutter closes

Rotary

Throttle

""Filter Screens

Tube Screen - Detachable Trap

Fig. 50. Sectional View of Master Carburetor Showing Parts.

off the air, throwing the suction on the jets, thus giving
a rich mixture.

The only adjustment is for idling, and once that is
fixed it need never be touched. This is in the form of
a screw and regulates the position of the throttle when
at idling position. The dash control has high-speed, nor-
mal and rich-starting positions. In installing the Master
carburetor the float chamber may be turned either toward
the radiator or driver's seat. If the float is turned toward
the radiator, however, a forward lug plate should be
ordered ; otherwise it will be difficult to install the control.
The throttle lever must go all the way to the stop lug

Compound Nozzle Zenith Carburetor 135

or maximum power will not be secured. In adjusting the
idle screw it is .turned in for rich and out for lean.

COMPOUND NOZZLE ZENITH CARBURETOR

The Zenith carburetor, shown at Fig. 51, has become
very popular for airplane engine use because of its sim-
plicity, as mixture compensation is secured by a compen-
sating compound nozzle principle that works very well in
practice. To illustrate this principle briefly, let us con-
sider the elementary type of carburetor or mixing valve,
as shown in Fig. 52, A. It consists of a single jet or
spraying nozzle placed in the path of the incoming air
and fed from the usual float chamber. It is a natural

PRIMING HOLE U

PRIMING TUBE J

REGULATING
SCREW O

BUTTERFLY T

SECONDARY
WELL P

CHOKE X

CAP JET H

MAIN JET O

COMPENSATOR I

Fig. 51. Sectional View of Zenith Compound Nozzle Compensating

Carburetor.

136

Aviation Engines

Action of Zenith Carburetor 137

inference to suppose that as the speed of the motor in-
creases, both the flow of air and of gasoline will increase
in the same proportion. Unhappily, such is not the case.
There is a law of liquid bodies which states that the flow
of gasoline from the jet increases under suction faster
than the flow of air, giving a mixture which grows richer
and richer a mixture containing a much higher percent-
age of gasoline at high suction than at low. The tendency
is shown by the accompanying curve (Fig. 52, B), which
gives the ratio of gasoline to air at varying speeds from
this type of jet. The mixture is practically constant only
between narrow limits and at very high speed. The most
common method of correcting this defect is by putting
various auxiliary air valves which, adding air, tends to
dilute this mixture as it gets too rich. It is difficult with
makeshift devices to gauge this dilution accurately for
every motor speed.

Now, if we have a jet which grows richer as the suction
increases, the opposite type of jet is one which would
grow leaner under similar conditions. Baverey, the in-
ventor of the Zenith, discovered the principle of the con-
stant flow device which is shown in Fig. 52, C. Here
a certain fixed amount of gasoline determined by the open-
ing I is permitted to flow by gravity into the well J open
to the air. The suction at jet H has no effect upon the
gravity compensator I because the suction is destroyed
by the open well J. The compensator, then, delivers a
steady rate of flow per unit of time, and as the motor
suction increases more air is drawn up, while the amount
of gasoline remains the same and the mixture grows
poorer and poorer. Fig. 52, D, shows this curve.

By combining these two types of rich and poor mixture
carburetors the Zenith compound nozzle was evolved. In
Fig. 52, E, we have both the direct suction or richer type
leading through pipe E and nozzle G and the "constant
flow" device of Baverey shown at J, I, K and nozzle H.
One counteracts the defects of the other, so that from
the cranking of the motor to its highest speed there is

138

Aviation Engines

a constant ratio of air and gasoline to supply efficient
combustion.

In addition to the compound nozzle the Zenith is
equipped with a starting and idling well, shown in the
cut of Model L carburetor at P and J. This terminates
in a priming hole at the edge of the butterfly valve,
where the suction is greatest when this valve is slightly
open. The gasoline is drawn up by the suction at the
priming hole and, mixed with the air rushing by the but-
terfly, gives an ideal slow speed mixture. At higher speeds

Mixing

Chambers-'

Float JBowh^
Cover \

Flood

Bowl ->

Fuel Inlet

Thro-H-le Discs

ThroH/e

Lever

.-Air Intake

Fig. 53. The Zenith Duplex Carburetor for Airplane Motors of the V Type.

with the butterfly valve opened further the priming well
ceases to operate and the compound nozzle drains the well
and compensates correctly for any motor speed.

With the coming of the double motor containing eight
or twelve cylinders arranged in two V blocks, the question
of good carburetion has been a problem requiring much
study. The single carburetor has given only indifferent
results due to the strong cross suction in the inlet mani-
fold from one set of cylinders to the other. This natur-
ally led to the adoption of two carburetors in which each
set of cylinders was independently fed by a separate car-

Zenith Carburetor Installation

139

buretor. Besults from this system were very good when
the two carburetors were working exactly in unison, but
as it was extremely difficult to accomplish this co-opera-
tion, especially where the adjustable type was employed,

,lntake Pipe

Air
Stove

Centrifugal
Water Pump

Flexible
Air Pipe-

Jacketed Manifold /
or Y Branch

Air Stove 1
Surrounding
Exhaust Pipes

Water Pipes
to Jacket

Flexible
Air Pipe

Zenith Duplex
Carburetor

Fig. 54. Rear View of Curtiss OX2 90 Horse-Power Airplane Motor
Showing Carburetor Location and Hot Air Leads.

this system never gained in favor. The next logical step
was the Zenith Duplex, shown at Fig. 53. This consists
of two separate and distinct carburetors joined together
so that a common gasoline float chamber and air inlet
could be used by both. It does away with cross suction
in the manifold because each set of cylinders has a sep-

140 Aviation Engines

arate intake of its own. It does away with two carburet-
ors and makes for simplicity. The practical application
of the Zenith carburetor to the Curtiss 90 horse-power
OX2 motor used on the J.N.4 standard training machine
is shown at Fig. 54, which outlines a rear view of the
engine in question. The carburetor is carried low to per-
mit of fuel supply from a gravity tank carried back of
the motor.

UTILITY OF GASOLINE STRAINERS J '

Many carburetors include a filtering screen at the point
where the liquid enters the float chamber in order to keep
dirt or any other foreign matter which may be present
in the fuel from entering the float chamber. This is not
general practice, however, and the majority of vaporizers
do not include a filter in their construction. It is very
desirable that the dirt should be kept out of the carbu-
retor because it may get under the float control fuel valve
and cause flooding by keeping it raised from its seat. If
it finds its way into the spray nozzle it may block the
opening so that no gasoline will issue .or may so constrict
the passage that only very small quantities of fuel will
be supplied the mixture. Where the carburetor itself is
not provided with a filtering screen a simple filter is
usually installed in the pipe line between the gasoline
tank and the float chamber.

Some simple forms of filters and separators are shown
at Fig. 55. That at A consists of a simple brass casting
having a readily detachable gauze screen and a settling
chamber of sufficient capacity to allow the foreign matter
to settle to "the bottom, from which it is drained out by
a pet cock. Any water or dirt in the gasoline will settle
to the bottom of the chamber, and as all fuel delivered
to the carburetor must pass through the wire gauze screen
it is not likely to contain impurities when it reaches the
float chamber. The heavier particles, such as scale from
the tank or dirt and even water, all of which have greater
weight than the gasoline, will sink to the bottom of the

Utility of Gasoline Strainers

141

chamber, whereas light particles, such as lint, will be pre-
vented from flowing into the carburetor by the filtering
screen.

The filtering device shown at B is a larger appliance
than that shown at A, and should be more efficient as a

Supporting Boss

Gasoline
from Tank

To Carburetor

Wire Gauze

To Carburetor

Wire Gauze

Settling Chambe
Settling Chamber

Gasoline Tan ft

Gasolin
from Tank

To Carburetor

Wire Gauze

To Carburetor.

Settling Chamber

Fig. 55. Types of Strainers Interposed Between Vaporizer and Gasoline
Tank to Prevent Water or Dirt Passing Into Carbureting Device.

separator because the gasoline is forced to pass through
three filtering screens before it reaches the carburetor.
The gasoline enters the device shown at C through a bent
pipe which leads directly to the settling chamber and
from thence through a wire gauze screen to the upper
compartment which leads to the carburetor. The device
shown at D is a combination strainer, drain, and sedi-

142 Aviation Engines

merit cup. The filtering screen is held in place by a
spring and both are removed by taking out a plug at the
bottom of the device. The shut-off valve at the top of
the device is interposed between the sediment cup and
the carburetor. This separating device is incorporated
with the gasoline tank and forms an integral part of the
gasoline supply system. The other types shown are de-
signed to be interposed between the gasoline tank and
the carburetor at any point in the pipe line where they
may be conveniently placed.

INTAKE MANIFOLD DESIGN AND CONSTRUCTION

On four- and six-cylinder engines and in fact on all
multiple-cylinder forms, it is important that the piping
leading from the carburetor to the cylinders be made in
such a way that the various cylinders will receive their
full quota of gas and that each cylinder will receive its
charge at about the same point in the cycle of operations.
In order to make the passages direct the bends should
be as few as possible, and when curves are necessary they
should be of large radius because an abrupt corner will not
only impede gas flow but will tend to promote condensation
of the fuel. Every precaution should be taken with f our-
and six-cylinder engines to insure equitable gas distri-
bution to the valve chambers if regular action of the
power plant is desired. If the gas pipe has many turns
and angles it will be difficult to charge all cylinders prop-
erly. On some six-cylinder aviation engines, two carbu-
retors are used because of trouble experienced with man-
ifolds designed for one carburetor. Duplex carburetors
are necessary to secure the best results from eight- and
twelve-cylinder V engines.

The problem of intake piping is simplified to some
extent on block motors where the intake passage is cored
in the cylinder casting and \vhere but one short pipe is
needed to join this passage to the carburetor. If the
cylinders are cast in pairs a simple pipe of T or Y form
can be used with success. When the engine is of a type

Intake Manifold Construction 143

using individual cylinder castings, especially in the six-
cylinder power plants, the proper application and instal-
lation of suitable piping is a difficult problem. The reader
is referred to the various engine designs outlined to as-
certain how the inlet piping has been arranged on repre-
sentative aviation engines. Intake piping is constructed
in two ways, the most common method being to cast the
manifold of brass or aluminum. The other method, which
is more costly, is to use a built-up construction of copper
or brass tubing with cast metal elbows and Y pieces. One
of the disadvantages advanced against the cast manifold
is that blowholes may exist which produce imperfect cast-
ings and which will cause mixture troubles because the
entering gas from the carburetor, which may be of proper
proportions, is diluted by the excess air which leaks in
through the porous casting. Another factor of some mo-
ment is that the roughness of the walls has a certain
amount of friction which tends to reduce the velocity of
the gases, and when projecting pieces are present, such
as core wire or other points of metal, these tend to collect
the drops of liquid fuel and thus promote condensation.
The advantage of the built-up construction is that the
walls of the tubing are very smooth, and as the castings
are small it is not difficult to clean them out thoroughly
before they are incorporated in the manifold. The tubing
and castings are joined together by hard soldering, braz-
ing or autogenous welding.

COMPENSATING FOR VARYING ATMOSPHERIC CONDITIONS

The low-grade gasoline used at the present time makes
it necessary to use vaporizers that are more susceptible
to atmospheric variations than when higher grade and
more volatile liquids are vaporized. Sudden temperature
changes, sometimes being as much as forty degrees rise
or fall in twelve hours, affect the mixture 'proportions to
some extent, and not only changes in temperature but
variations in altitude also have a bearing on mixture pro-
portions by affecting both gasoline and air. As the tern-

144

Aviation Engines

perature falls the specific gravity of the gasoline increases
and it becomes heavier, this producing difficulty in vapor-
izing. The tendency of very cold air is to condense gas-
oline instead of vaporizing it and therefore it is necessary
to supply heated air to some carburetors to obtain proper
mixtures during cold weather. In order that the gas mix-
tures will ignite properly the fuel must be vaporized and
thoroughly mixed with the entering air either by heat or

Atmospheric Pressure, Ibs. per sq.in.
^oi 5 < F3 o CP o

'^#

/?.

) ZOOO 4000 6000 8000 10.000
Altitude in Feet Above Sea Level

Fig. 56. Chart Showing Diminution of Air Pressure as Altitude Increases.

high velocity of the gases. The application of air stoves
to the Curtiss* 0X2 motor is clearly shown at Fig. 54. It
will be seen that flexible metal pipes are used to convey
the heated air to the air intakes of the duplex mixing
chamber.

HOW HIGH ALTITUDE AFFECTS POWER

Any internal combustion engine will show less power
at high altitudes than it will deliver at sea level, and this
has caused a great deal of questioning. "There is a good

How High Altitude Affects Power 145

reason for this," says a writer in " Motor Age," "and
it is a physical impossibility for the engine to do other-
wise. The difference is due to the lower atmospheric
pressure the higher up we get. That is, at sea level the
atmosphere has a pressure of 14.7 pounds per square inch ;
at 5,000 feet above sea level the pressure is approximately
12.13 pounds per square inch, and at 10,000 feet it is 10
pounds per square inch. From this it will be seen that
the final pressure attained after the piston has driven
the gas into compressed condition ready for firing is lower
as the atmospheric pressure drops. This means that there
is not so much power in the compressed charge of gas the
higher up you get above sea level.

"For example, suppose the compression ratio to be
4^2 to 1; in other words, suppose the air space above the
piston to have 4^ times the volume when the piston is
at the bottom of its stroke that it has when the piston is
at the top of the stroke. That is a common compression
ratio for an average motor, and is chosen because it is
considered to be the best for maximum horse-power and
in order that the compression pressure will not be % so high
as to cause pre-ignition. Knowing the compression ratio,
we can determine the final pressure immediately before
ignition by substituting in the standard formula:

1.3

in which P is the atmospheric pressure; P 1 is the final

pressure, and is the compression ratio, therefore P 1 =
V 1

14.7 (4.5) 1>3 = 104 pounds per square inch, absolute.

"That is, 104 pounds per square inch is the most effi-
cient final compression pressure to have for this engine
at sea level, since it comes directly from the compression
ratio.

"Now supposing we consider that the altitude is 7,000

146 Aviation Engines

feet above sea level. At this height the atmospheric press-
ure is 11.25 pounds per square inch, approximately. In
this case we can again substitute in the formula, using
the new atmospheric pressure figure. The equation be-
comes :

P 1 11.25 ( 4.5) i- 3 79.4 pounds per square inch, ab-
solute.

"Therefore we now have a final compression pressure
of only 79.4 pounds per square inch, which is considerably
below the pressure we have just found to be the most
efficient for the motor. The resulting power drop is evi-
dent.

"It should be borne in mind that these final compres-
sion pressures are absolute pressures that is, they in-
clude the atmospheric pressure. In the first case, to get
the pressure above atmospheric you would subtract 14.7
and in the latter 11.25 would have to be deducted. In
other words, where the sea level compression is 89.3 pounds
per square inch above the atmosphere, the same motor
will hav,e only a compression pressure of 68.15 pounds
per square inch above the atmosphere at 7,000 feet ele-
vation.

"From the above it is evident that in order to bring
the final compression pressure up to the efficient figure
we have determined, a different compression ratio would
have to be used. That is, the final volume would have
to be less, and as it is impossible to vary this to meet
the conditions of altitude, the loss of power cannot be
helped except by the replacing of the standard pistons
with some that are longer above the wrist-pin so as to
reduce the space above the pistons when on top center.
Then if the ratio is thereby raised to some such figures
as 5 to 1, the engine will again have its proper final press-
ure, but it will still not have as much power as it would
have at sea level, since the horse-power varies directly
with the atmospheric pressure, final compression being
kept constant. That is, at 7,000 feet the horse-power of

The Diesel System 147

an engine that had 40 horse-power at sea level would be
equal to

11.25

- 30 . 6 horse-power.

14.7

"If the original compression ratio of 4.5 were retained,
the drop in horse-power would be even greater than this.
These computations and remarks will make it clear that
the designer who contemplates building an airplane for
high altitude use should see to it that it is of sufficient
power to compensate for the drop that is inevitable when
it is up in the air. This is often illustrated in stationary
gas-engine installations. An engine that had a sea-level
rating amply sufficient for the work required, might not
be powerful enough when brought up several thousand
feet." When one considers that airplanes attain heights
of over 18,000 feet, it will be evident that an ample mar-
gin of engine power is necessary,

THE DIESEL SYSTEM

A system of fuel supply developed by the late Dr.
Diesel, a German chemist and engineer, is attracting con-
siderable attention at the present time on account of the
ability of the Diesel engine to burn low-grade fuels, such
as crude petroleum. In this system the engines are built
so that very high compressions are used, and only pure
air is taken into the cylinder on the induction stroke.
This is compressed to a pressure of about 500 pounds
per square inch, and sufficient heat is produced by this
compression to explode a hydrocarbon mixture. As the
air which is compressed to this high point cannot burn,
the fuel is introduced into the cylinder combustion cham-
ber under still higher compression than that of the com-
pressed air, and as it is injected in a fine stream it is
immediately vaporized because of the heat. Just as soon
as the compressed air becomes thoroughly saturated with
the liquid fuel, it will explode on account of the degree of

148 Aviation Engines

heat present in the combustion chamber. Such motors
have been used in marine and stationary applications, but
are not practical for airplanes or motor cars because of
lack of flexibility and great weight in proportion to power
developed. The Diesel engine is the standard power plant
used in submarine boats and motor ships, as its efficiency
renders it particularly well adapted for large units.

NOTES ON CAKBUKETOK INSTALLATION IN AIRPLANES

A writer in "The Aeroplane," an English publication,
discourses on some features of carburetor installation that
may be of interest to the aviation student, so portions of
the dissertation are reproduced herewith.

" Users of airplanes fitted with ordinary type carburetors will
do well to note carefully the way in which these are fitted, for
several costly machines have been burnt lately through the sheer
carelessness of their users. These particular machines were fitted
with a high powered V-type engine, made by a firm which is
famous as manufacturers of automobiles de luxe. In these engines
there are four carburetors, mounted in the V between the cylinders.
When the engine is fitted as a tractor, the float chambers are in
front of the jet chambers. Consequently, when the tail of the
machine is resting on the ground, the jets are lower than the level
of the gasoline in the float chamber.

"Quite naturally, the gasoline runs out of the jet, if it is left
turned on when the machine is standing in its normal position,
and trickles into the V at the top of the crank-case. Thence it
runs down to the tail of the engine, where the magnetos are fitted;
and saturates them. If left long enough, the gasoline manages
to soak well into the fuselage before evaporating. And what does
evaporate makes an inflammable gas in the forward cockpit. Then
some one comes along and starts up the engine. The spark-gap
of the magneto gives one flash, and the whole front of the machine
proceeds to give a Fourth of July performance forthwith. Natu-
rally, one safeguard is to turn the petrol off directly the machine
lands. Another is never to turn it on till the engine is actually
being started up.

"One would be asking too much of the human boy who is
officially regarded as the only person fit to fly an aeroplane if
one depended upon his memory of such a detail to save his ma-
chine, though one might perhaps reasonably expect the older pilots
to remember not to forget. Even so, other means of prevention

Notes on Carburetor Installation 149

are preferable, for fire is quite as likely to occur from just the
same cause if the engine happens to be a trifle obstinate in start-
ing, and so gives the carburetors several minutes in which to drip
in which operation they would probably be assisted by air-
mechanics 'tickling' them.

"One way out of the trouble is to fit drip tins under the jet
chamber to catch the gasoline as it falls. This is all very well
just to prevent fire while the machine is being started up, but it
will not save it if it is left standing with the tail on the ground
and the petrol turned on, for the drip tins will then fill up and
run over. And if it catches then, the contents of the drip tins
merely add fuel to the fire.

Reversing Carburetors

"Yet another way is to turn the carburetors round, so that
the float chambers are behind the jets, and so come below them
when the tail is on the ground, thus cutting off the gasoline low
down in the jets. There seems to be no particular mechanical
difficulty about this, though I must confess that I did not note
very carefully whether the reversal of the float chambers would
make them foul any other fittings on the engine. It has been
argued, however, that doing this would starve the engine of gaso-
line when climbing at a steep angle, as the gasoline would then
be lowered in the jets and need more suction to get into the
cylinders. This is rather a pretty point of amateur motor me-
chanics to discuss, for, obviously, when the same engine is used
as a 'pusher' instead of a tractor, the jets are in front of the
floats, and there seems to be no falling off in power.

Starvation of Mixture

"Moreover, the higher a machine goes the lower is the atmos-
pheric pressure, and, consequently, the less is the amount of air
sucked in at each induction stroke. This means, of course, that
with the gasoline supply the mixture at high altitudes is too
rich, so that, in order to get precisely the right mixture when very
high up, it is necessary to reduce the gasoline supply by screwing
down the needle valve between the tank and the carburetor at
least, that has been the experience of various high-flying pilots.
No doubt something might be done in the way of forced air feed
to compensate for reduced atmospheric pressure, but it remains
to be proved whether the extra weight of mechanism involved
would pay for the extra power obtained. Variable compression
might do something, also, to even things up, but here, also, weight-
of mechanism has to be considered.

"In any case, at present, the higher one goes the more the

150 Aviation Engines

power of the engine is reduced, for less air means a less volume
of mixture per cylinder, and as the petrol feed has to be starved
to suit the smaller amount of air available, this means further loss
of power. I do not know whether anyone has evolved a carbu-
retor which automatically starves the gasoline feed when high up,
but it seems possible that when an airplane is sagging about 'up
against the ceiling' as a French pilot described the absolute
limit of climb for his particular machine it might be a good
thing to have the jets in front of the float chamber, for then a
certain amount of automatic starvation would take place.

"When a machine is right up at its limiting height, and the
pilot is doing his best to make it go higher still, it is probably
flying with its tail as low as the pilot dares to let it go, and the
lateral and longitudinal controls are on the verge of vanishing,
so that if the carburetor jets are behind the float chambers there
is bound to be an over-rich mixture in any case. There is even
a possibility of a careless or ignorant pilot carrying on in this tail-
down position till one set of cylinders cuts out altogether, in which
case the carburetor feeding that set may flood over, just as if the
machine were on the ground, and the whole thing may catch fire.
Whereas, with the jets in front of the floats, though the mixture
may starve a trifle, there is, at any rate, no danger of fire through
climbing with the tail down.

A Diving Danger

"On the other hand, in a 'pusher' with this type of engine,
if the jets are in their normal position which is in front of the
floats there is danger of fire in a dive. That is to say, if the
pilot throttles right down, or switches off and relies on air pres-
sure on his propeller to start the engine again, so that the gasoline
is flooding over out of the jets instead of being sucked into the
engine, there may be flooding over the magnetos if the dive is very
steep and prolonged. In any case, a long dive will mean a certain
amount of flooding, and, probably, a good deal of choking and
spitting by the engine before it gets rid of the over-rich mixture
and picks up steady firing again. Which may indicate to young
pilots that it is not good to come down too low under such cir-
cumstances, trusting entirely to their engines to pick up at once
and get going before they hit the ground.

' ' On the whole, it .seems that it might be better practice to set
the carburetors thwartwise of engines, for then jets and floats
would always be at approximately the same level, no matter what
the longitudinal position of the machine, and it is never long
enough in one positiqn at a big lateral angle to raise any serious
carburetor troubles. Car manufacturers who dive cheerfully into

Notes on Carburetor Adjustment 151

the troubled waters of aero-engine designs are a trifle apt to forget
that their engines are put into positions on airplanes which
would be positively indecent in a motor car. An angle of 1 in 10
is the exception on a car, but it is common on an airplane, and
no one ever heard of a car going down a hill of 10 to 1 which is
not quite a vertical dive. Therefore, there is every excuse for a
well-designed and properly brought-up carburetor misbehaving
itself in an aeroplane.

"It seems, then, that it is up to the manufacturers to produce
better carburetors say, with the jet central with the float. But
it also behooves the user to show ordinary common sense in han-
dling the material at present available, and not to make a prac-
tice of burning up $25,000 worth or so of airplane just because
he is too lazy to turn off his gasoline, or to have the tail of his
machine lifted up while he is tinkering with his engines. ' '

NOTES ON CARBURETOR ADJUSTMENT

The modern float feed carburetor is a delicate and
nicely balanced appliance that requires a certain amount
of attention and care in order to obtain the best results.
The adjustments can only be made by one possessing an
intelligent knowledge of carburetor construction and must
never be made unless the reason for changing the old ad-
justment is understood. Before altering the adjustment
of the leading forms of carburetors, a few hints regarding
the quality to be obtained in the mixture should be given
some consideration, as if these are properly understood
this knowledge will prove of great assistance in adjusting
the vaporizer to give a good working proportion of fuel
and air. There is some question regarding the best mix-
ture proportions and it is estimated that gas will be
explosive in which the proportions of fuel vapor and air
will vary from one part of the former to a wide range
included between four and eighteen parts of the latter.
A one to four mixture is much too rich, while the one
in eighteen is much too lean to provide positive ignition.

A rich mixture should be avoided because the excessive
fuel used will deposit carbon and will soot the cylinder
walls, combustion chamber interior, piston top and valves
and also tend to overheat the motor. A rich mixture will

152 Aviation Engines

also seriously interfere with flexible control of the engine,
as it will choke up on low throttle and run well on open
throttle when the full amount of gas is needed. A rich
mixture may be quickly discovered by black smoke issuing
from the muffler, the exhaust gas having a very pungent
odor. If the mixture contains a surplus of air there will
be popping sounds in the carburetor, which is commonly
termed "blowing back." To adjust a carburetor is not
a difficult matter when the purpose of the various control
members is understood. The first thing to do in adjusting
a carburetor is to start the motor and to retard the spark-
ing lever so the motor will run slowly leaving the throttle
about half open. In order to ascertain if the mixture is
too rich cut down the gasoline flow gradually by screwing
down the needle, valve until the motor commences to run
irregularly or misfire. Close the needle valves as far as
possible without having the engine come to a stop, and
after having found the minimum amount of fuel gradually
unscrew the adjusting valve until you arrive at the point
where the engine develops its highest speed. "When this
adjustment is secured the lock nut is screwed in place so
the needle valve will keep the adjustment. The next point
to look out for is regulation of the auxiliary air supply on
those types of carburetors where an adjustable air valve
is provided. This is done by advancing the spark lever
and opening the throttle. The air valve is first opened
or the spring tension reduced to a point where the engine
misfires or pops back in the carburetor. When the point
of maximum air supply the engine will run on is thus de-
termined, the air valve spring may be tightened by screw-
ing in on the regulating screw until the point is reached
where an appreciable speeding up of the engine is noticed.
If both fuel and air valves are set right, it will be possible
to accelerate the engine speed uniformly without interfer-
ing with regularity of engine operation by moving the
throttle lever or accelerator pedal from its closed to its
wide open position, this being done with the spark lever
advanced. All types of carburetors do not have the same

Notes on Carburetor Adjustment 153

means of adjustment; in fact, some adjust only with the
gasoline regulating needle; others must have a complete
change of spray nozzles; while in others the mixture pro-
portions may be varied only by adjustment of the quantity
of entering air. Changing the float level is effective in
some carburetors, but this should never be done unless it
is certain that the level is not correct. Full instructions
for locating carburetion troubles will be given in proper
sequence.

It is a fact well known to experienced repairmen and
motorists that atmospheric conditions have much to do
with carburetor action. It is often observed that a motor
seems to develop more power at night than during the
day, a circumstance which is attributed to the presence of
more moisture in the cooler night air. Likewise, taking
a motor from sea level to an altitude of 10,000 feet in-
volves using rarefied air in the engine cylinders and at-
mospheric pressures ranging from 14.7 pounds at sea
level to 10.1 pounds per square inch at the high altitude.
All carburetors will require some adjustment in the course
of any material change from one level to another. Great
changes of altitude also have a marked effect on the cool-
ing system of an airplane. Water boils at 212 degrees F.
only at sea level. At an altitude of 10,000 feet it will,
boil at a temperature nineteen degrees lower, or 193 de-
grees F.

In high altitudes the reduced atmospheric pressure,
for 5,000 feet or higher than sea level, results in not
enough air reaching the mixture, so that either the auxil-
iary air opening has to be increased, or the gasoline in
the mixture cut down. If the user is to be continually
at high altitudes he should immediately purchase either
a larger dome or a smaller strangling tube, mentioning
the size carburetor that is at present in use and the type
of motor that it is on, including details as to the bore
and stroke. The smaller strangling tube makes an in-
creased suction at the spray nozzle ; the air will have to
be readjusted to meet it and you can use more auxiliary

154 Aviation Engines

air, which is necessary. The effect on the motor without
a smaller strangling tube is a perceptible sluggishness and
failure to speed up to its normal crank-shaft revolutions,
as well as failure to give power. It means that about one-
third of the regular speed is cut out. The reduced at-
mospheric pressure reduces the power of the explosion,
in that there is not the same quantity of oxygen in the
combustion chamber as at sea level ; to increase the amount
taken in, you must also increase the gasoline speed, which
is done by an increased suction through the smaller stran-
gling aperture. Some forms of carburetors are affected
more than others by changes of altitude, which explains
why the Zenith is so widely employed for airplane engine
use. The compensating nozzle construction is not influ-
enced as much by changes of altitude as the simpler nozzle
types are.

CHAPTER VI

Early Ignition Systems Electrical Ignition Best Fundamentals of
Magnetism Outlined Forms of Magneto Zones of Magnetic In-
fluence How Magnets are Made Electricity and Magnetism
Related Basic Principles of Magneto Action Essential Parts of
Magneto and Functions Transformer Coil Systems True High
Tension Type The Berling Magneto Timing and Care The
Dixie Magneto Spark Plug Design and Application Two-Spark
Ignition Special Airplane Plug.

EAKLY IGNITION SYSTEMS , %

ONE of the most important auxiliary groups of the
gasoline engine comprising the airplane power plant and
one absolutely necessary to insure engine action is the
ignition system or the method employed of kindling the
compressed gas in the cylinder to produce an explosion
and useful power. The ignition system has been fully
as well developed as other parts of the engine, and at
the present time practically all ignition systems follow
principles which have become standard through wide ac-
ceptance.

During the early stages of development of the gasoline
engine various methods of exploding the charge of com-
bustible gas in the cylinder were employed. On some of
the earliest engines a flame burned close to the cylinder
head, and at the proper time for ignition a slide or valve
moved to provide an opening which permitted the flame
to ignite the gas back of the piston. This system was
practical only on the primitive form of gas engines in
which the charge was not compressed before ignition.
Later, when it was found desirable to compress the gas
a certain degree before exploding it, an incandescent plat-
inum tube in the combustion chamber, which was kept
in a heated condition by a flame burning in it, exploded
the gas. The naked flame was not suitable in this appli-

155

156 Aviation Engines

cation because when the slide was opened to provide com-
munication between the flame and the gas the compressed
charge escaped from the cylinder with enough pressure to
blow out the flame at times and thus cause irregular ig-
nition. When the flame was housed in a platinum tube
it was protected from the direct action of the gas, and
as long as the tube was maintained at the proper point
of incandescence regular ignition was obtained.

Some engineers utilized the property of gases firing
themselves if compressed to a sufficient degree, while
others depended upon the heat stored in the cylinder-head
to fire the highly compressed gas. None of these methods
were practical in their application to motor car engines
becanise they did not permit flexible engine action which
is so desirable. At the present time, electrical ignition
systems in which the compressed gas is exploded by the
heating value of the minute electric arc or spark in the
cylinder are standard, and the general practice seems to
be toward the use of mechanical producers of electricity
rather than chemical batteries.

ELECTRICAL IGNITION BEST

Two general forms of electrical ignition systems may
be used, the most popular being that in which a current
of electricity under high tension is made to leap a gap
or air space between the points of the sparking plug
screwed into the cylinder. The other form, which has
been almost entirely abandoned in automobile and which
was never used with airplane engine practice, but which
is still used to some extent on marine engines, is called
the low-tension system because current of 'low voltage is
used and the spark is produced by moving electrodes in
the combustion chamber.

The essential elements of any electrical ignition sys-
tem, either high or low tension, are: First, a simple and
practical method of current production; second, suitable
timing apparatus to cause the spark to occur at the right
point in the cycle of engine action; third, suitable wiring

Fundamentals of Magnetism 157

and other apparatus to convey the current produced by
the generator to the sparking member in the cylinder.

The various appliances necessary to secure prompt ig-
nition of the compressed gases should be described in some
detail because of the importance of the ignition system.
It is patent that the scope of a work of this character
does not permit one to go fully into the theory and prin-
ciples of operation of all appliances which may be used
in connection with gasoline motor ignition, but at the same
time it is important that the elementary principles be
considered to some extent in order that the reader should
have a proper understanding of the very essential ignition
apparatus. The first point considered will be the common
methods of generating the electricity, then the appliances
to utilize it and produce the required spark in the cylin-
der. Inasmuch as magneto ignition is universally used
in connection with airplane engine ignition it will not be
necessary to consider battery ignition systems.

FUNDAMENTALS OF MAGNETISM OUTLINED

To properly understand the phenomena and forces in-
volved in the generation of electrical energy by mechanical
means it is necessary to become familiar with some of the
elementary principles of magnetism and its relation to
electricity. The following matter can be read with profit
by those who are not familiar with the subject. Most
persons know that magnetism exists in certain substances,
but many are not able to grasp the terms used in describ-
ing the operation of various electrical devices because of
not possessing a knowledge of the basic facts upon which
the action of such apparatus is based.

Magnetism is a property possessed by certain sub-
stances and is manifested by the ability to attract and
repel other materials susceptible to its effects. "When this
phenomenon is manifested by a conductor or wire through
which a current of electricity is flowing it is termed "elec-
tro-magnetism." Magnetism and electricity are closely
related, each being capable of producing the other. Prac-

160 Aviation Engines

the size of the magnets used and the air gap separating
the poles. If the south pole of one magnet is brought
close to the end of the same polarity of the other there
will be a pronounced repulsion of like force. These facts
are easily proved by the simple experiment outlined at
B, Fig. 57. A magnet will only attract or influence a
substance having similar qualities. The like poles of
magnets will repel each other because of the obvious im-
possibility of uniting two influences or forces of practi-
cally equal strength but flowing in opposite directions.
The unlike poles of magnets attract each other because
the force is flowing in the same direction. The flow of
magnetism is through the magnet from south to north and
the circuit is completed by the flow of magnetic influence
through the air gap or metal armature bridging it from
the north to the south pole.

FOKMS OF MAGNETS AND ZONE OF MAGNETIC INFLUENCE

DEFINED J 4

Magnets are commonly made in two forms, either in
the shape of a bar or horseshoe. These two forms are
made in two types, simple or compound. The latter are
composed of a number of magnets of the same form united
so the ends of like polarity are laced together, and such
a construction will be more efficient and have more strength
than a simple magnet of the same weight. The two com-
mon forms of simple and compound magnets are shown
at C, Fig. 57. The zone in which a magnetic influence
occurs is called the magnetic field, and this force can be
graphically shown by means of imaginary lines, which
are termed "lines of force." As will be seen from the
diagram at D, Fig. 57, the lines show the direction of
action of the magnetic force and also show its strength,
as they are closer together and more numerous when the
intensity of the magnetic field is at its maximum. A
simple method of demonstrating the presence of the force
is to lay a piece of thin paper over the pole pieces of either
a bar or horseshoe magnet and sprinkle fine iron filings

Magnets and Zone of Influence 161

on it. The particles of metal arrange themselves in very
much the manner shown in the illustrations and prove
that the magnetic field actually exists.

The form of magnet used will materially affect the
size and area of the magnetic field. It will be noted that
the field will be concentrated to a greater extent with
the horseshoe form because of the proximity of the poles.
It should be understood that these lines have no actual
existence, but are imaginary and assumed to exist only
to show the way the magnetic field is distributed. The
magnetic influence is always greater at the poles than
at the center, and that is why a horseshoe or U-form
magnet is used in practically all magnetos or dynamos.
This greater attraction at the poles can be clearly dem-
onstrated by sprinkling iron filings on bar and U mag-
nets, as outlined at E, Fig. 57. A large mass gathers at
the pole pieces, gradually tapering down toward the point
where the attraction is least.

From the diagrams it will be seen that the flow of
magnetism is from one pole to the other by means of
curved paths between them. This circuit is completed
by the magnetism flowing from one pole to the other
through the magnet, and as this flow is continued as long
as the body remains magnetic it constitutes a magnetic
circuit. If this flow were temporarily interrupted by
means of a conductor of electricity moving through the
field there would be a current of electricity induced in
the conductor every time it cut the lines of force. There
are three kinds of magnetic circuits. A non-magnetic
circuit is one in which the magnetic influence completes
its circuit through some substance not susceptible to the
force. A closed magnetic circuit is one in which the in-
fluence completes its circuit through some, magnetic ma-
terial which bridges the gap between the poles. A com-
pound circuit is that in which the magnetic influence
passes through magnetic substances and non-magnetic sub-
stances in order to complete its circuit.

162 Aviation Engines

HOW IRON AND STEEL BARS ARE MADE MAGNETIC

Magnetism may be produced in two ways, by contact
or induction. If a piece of steel is rubbed on a magnet
it will be found a magnet when removed, having a north
and south pole and all of the properties found in the
energizing magnet. This is magnetizing by contact. A
piece of steel will retain the magnetism imparted to it for
a considerable length of time, and the influence that re-
mains is known as residual magnetism. This property
may be increased by alloying the steel with tungsten and
hardening it before it is magnetized. Any material that
will retain its magnetic influence after removal from the
source of magnetism is known as a permanent magnet.
If a piece of iron or steel is brought into the magnetic
field of a powerful magnet it becomes a magnet without
actual contact with the energizer. This is magnetizing
by magnetic induction. If a powerful electric current
flows through an insulated conductor wound around a
piece of iron or steel it will make a magnet of it. This
is magnetizing by electro-magnetic induction. A magnet
made in this manner is termed an electro-magnet and
usually the metal is of such a nature that it will not
retain its magnetism when the current ceases to flow
around it. Steel is used in all cases where permanent
magnets are required, while soft iron is employed in all
cases where an intermittent magnetic action is desired.
Magneto field magnets are always made of tungsten steel
alloy, so treated that it will retain its magnetism for
lengthy periods.

ELECTRICITY AND MAGNETISM CLOSELY RELATED

There are many points in which magnetism and elec-
tricity are alike. For instance, air is a medium that of-
fers considerable resistance to the passage of both mag-
netic influence and electric energy, although it offers more
resistance to the passage of the latter. Minerals like
iron or steel are very easily influenced by magnetism and

Principles of Magneto Outlined 163

easily penetrated by it. When one of these is present
in the magnetic circuit the magnetism will flow through
the metal. Any metal is a good conductor for the pas-
sage of the electric current, but few metals are good
conductors of magnetic energy. A body of the proper
metal will become a magnet due to induction if placed
in the magnetic field, having a south pole where the lines
of force enter it and a north pole where they pass out.

We have seen that a magnet is constantly surrounded
by a magnetic field and that an electrical conductor when
carrying a current is also surrounded by a field of mag-
netic influence. Now if the conductor carrying a current
of electricity will induce magnetism in a bar of iron or
steel, by a reversal of this process, a magnetized iron or
steel bar will produce a current of electricity in a con-
ductor. It is upon this principle that the modern dynamo
or magneto is constructed. If an electro-motive force is
induced in a conductor by moving it across a field of mag-
netic influence, or by passing a magnetic field near a
conductor, electricity is said to be generated by magneto-
electric induction. All mechanical generators of the elec-
tric current using permanent steel magnets to produce a
field of magnetic influence are of this type*.

BASIC PRINCIPLES OF MAGNETO OUTLINED

The accompanying diagram, Fig. 58, will show these
principles very clearly. As stated on an earlier page,
if the lines of force in the .magnetic field are cut by a
suitable conductor an electrical impulse will be produced
in that conductor. In this simple machine the lines of
force exist between the poles of a horseshoe magnet. The
conductor, which in this case is a loop of copper wire,
is mounted upon a spindle in order that it may be rotated
in the magnetic field to cut the lines of magnetic influ-
ence present between the pole pieces. Both of the ends
of this loop are connected, one with the insulated drum
shown upon the shaft, the other to the shaft. Two metal
brushes are employed to collect the current and cause it

164

Aviation Engines

to flow through the external circuit. It can be seen that
when the shaft is turned in the direction of the arrow
the loop will cut through the lines of magnetic influence
and a current will be generated therein.

Insulated Ring'
Loop of Wire
Spindle

Brushes*

Fig. 58. Elementary Form of Magneto Showing Principal Parts Simplified
to Make Method of Current Generation Clear.

The pressure of the current and the amount produced
vary in accordance to the rapidity with which the lines
of magnetic influence are cut. The armature of a practi-
cal magneto, therefore, differs materially from that shown
in the diagram. A large number of loops of wire would
be mounted upon this shaft in order that the lines of
magnetic influence would be cut a greater number of times
in a given period and a core* of iron used as a backing

Magneto Operating Principles

165

for the wire. This would give a more rapid alternating
current and a higher electro-motive force than would bo
the case with a smaller number of loops of wire.

The illustrations at Fig. 59 show a conventional double

Field
Magnets

Armature

Pole / Pole

Pieces ^J Pieces

Fig. 59. Showing How Strength of Magnetic Influence and of the Currents
Induced in the Windings of Armature Vary with the Eapidity of
Changes of riow.

166 Aviation Engines

winding armature and field magnetic of a practical mag-
neto in part section and will serve to more fully em-
phasize the points previously made. If the armature or
spindle were removed from between the pole pieces there
would exist a field of magnetic influence as shown at Fig.
57, but the introduction of this component provides a
conductor (the iron core) for the magnetic energy, re-
gardless of its position, though the facility with which
the influence will be transmitted depends entirely upon
the position of the core. As shown at A, the magnetic
flow is through the main body in a straight line, while
at B, which position the armature has attained after one-
eighth revolution, or 45 degrees travel in the direction
of the arrow, the magnetism must pass through in the
manner indicated. At C, which position is attained every
half revolution, the magnetic energy abandons the longer
path through the body of the core for the shorter passage
offer 3d by the side pieces, and the field thrown out by the
cross bar disappears. On further rotation of the arma-
ture, as at D, the body of the core again becomes ener-
gized as the magnetic influence resumes its flow through
it. These changes in the strength of the magnetic field
when distorted by the armature core, as well as the in-
tensity of the energy existing in the field, affect the
windings, and the electrical energy induced therein cor-
responds in strength to the rapidity with which these
changes in magnetic flow occur. The most pronounced
changes in the strength of the field will occur as the ar-
mature passes from position B to D, because the magnetic
field existing around the core will be destroyed and again
re-established.

During the most of the armature rotation the changes
in strength will be slight and the currents induced in the
wire correspondingly small; but at the instant the core
becomes remagnetized, as the armature leaves position C,
the current produced will be at its maximum, and it is nec-
essary to so time the rotation of the armature that at this
instant one of the cylinders is in condition to be fired. It

Essential Parts of a Magneto 167

is imperative that the armature be driven in such relation
to the crank- shaft that each production of maximum cur-
rent coincides with the ignition point, this condition exist-
ing twice during each revolution of the armature, or at
every 180 degrees travel. Each position shown corre-
sponds to 45 degrees travel of the armature, or one-eighth
of a turn, and it takes just three-eighths revolution to
change the position from A to that shown at D.

ESSENTIAL PARTS OF A MAGNETO AND THEIR FUNCTIONS

The magnets which produce the influence that in turn
induces the electrical energy in the winding or loops of
wire on the armature, and which may have any even
number of opposed poles, are called field magnets. The
loops of wire which are mounted upon a suitable drum
and rotate in the field of magnetic inflence in order to
cut the lines of force is called an armature winding, while
the core is the metal portion. The entire assembly is
called the armature. The exposed ends of the magnets
are called pole pieces and the arrangement used to collect
the current is either a commutator or a collector. The
stationary pieces which bear against the collector or com-
mutator and act as terminals for the outside circuit are
called brushes. These brushes are often of copper, or
some of its alloys, because copper has a greater electrical
conductivity than any other metal.

These brushes are nearly always of carbon, which
is sometimes electroplated with copper to increase its
electrical conductivity, though cylinders of copper wire
gauze impregnated with graphite are utilized at times.
Carbon is used because it is not so liable to cut the metal
of the commutator as might be the case if the contact was
of the metal to metal type. The reason for this is that
carbon has the peculiar property in that it materially as-
sists in the lubrication of the commutator, and being of
soft, unctuous composition, will wear and conform to any
irregularities on the surface of the metal collector rings.

The magneto in common use consists of a number of

168 Aviation Engines

horseshoe magnets which are compound in form and at-
tached to suitable cast-iron pole pieces used to collect and
concentrate the magnetic influence of the various magnets.
Between these pole pieces an armature rotates. This is
usually shaped like a shuttle, around which are wound
coils of insulated wire. These are composed of a large
number of turns and the current produced depends in
great measure upon the size of the wire and the number
of turns per coil. An armature winding of large wire will
deliver a current of great amperage, but of small voltage.
An armature wound with very fine wire will deliver a
current of high voltage but of low amperage. In the
ordinary form of magneto, such as used for ignition, the
current is alternating in character and the break in the
circuit should be timed to occur when the armature is at
the point of its greatest potential or pressure. Where
such a generator is designed for direct current production
the ends of the winding are attached to the segments of
a commutator, but where the instrument is designed to
deliver an alternating current one end of the winding is
fastened to an insulator ring on one end of the armature
shaft and the other end is grounded on the frame of the
machine.

The quantity of the current depends upon the strength
of the magnetic field and the number of lines of magnetic
influence acting through the armature. The electro-motive
force varies as to the length of the armature winding and
the number of revolutions at which the armature is rotated.

THE TRANSFORMER SYSTEM USES LOW VOLTAGE MAGNETO

The magneto in the various systems which employ a
transformer coil is very similar to a low-tension genera-
tor in general construction, and the current delivered at
the terminals seldom exceeds 100 volts. As it requires
many times that potential or pressure to leap the gap
which exists between the points of the conventional spark
plug, a separate coil is placed in circuit to intensify the
current to one of greater capacity. The essential parts

Transformer Coil-Magneto System

169

of such a system and their relation to each other are
shown in diagrammatic form at Fig. 60 and as a com-
plete system at Fig. 61. As is true of other systems the
magnetic influence is produced by permanent steel mag-
nets clamped to the cast-iron pole pieces between which
the armature rotates. At the point of greatest potential

Distributor Plate
Distributor Arm

Armature

/WWWVWVWWW-1

Secondary Winding nx j[ WA

Interrupter

Adjustment / \Qrounded

Insulated Contact

Contact

Fig. 60. Diagrams Explaining Action of Low Tension Transformer Coil and
True High Tension Magneto Ignition Systems.

in the armature winding the current is broken by the
contact breaker, which is actuated by a cam, and a cur-
rent of higher value is induced in the secondary winding
of the transformer coil when the low voltage current is
passed through the primary winding.

It will be noted that the points of the contact breaker
are together except for the brief instant when separated
by the action of the point of the cam upon the lever. It
is obvious that the armature winding is short-circuited

170

Aviation Engines

Transformer Coil-Magneto System

171

upon itself except when the contact points are separated.
While the armature winding is thus short-circuited there
will be practically no generation of current. When the
points are separated there is a sudden flow of current
through the primary winding of the transformer coil, in-
ducing a secondary current in the other winding, which
can be varied in strength by certain considerations in the

To Second Set
Spark Plugs

6 Volt Battery

Fig. 61. Berling Two-Spark Dual Ignition System.

preliminary design of the apparatus. This current of
higher potential or voltage is conducted directly to the
plug if the device is fitted to a single-cylinder engine, or
to the distributor arm if fitted to a multiple-cylinder mo-
tor. The distributor consists of an insulator in which is
placed a number of segments, one for each cylinder to
be fired, and so spaced that the number of degrees be-
tween them correspond to the ignition points of the motor.
A two-cylinder motor would have two segments, a three-
cylinder, three segments, and so on within the capacity
of the instrument. In the illustration a four-cylinder dis-
tributor is fitted, and the distributing arm is in contact

172

. Aviation Engines

with the segment corresponding to the cylinder about to
be fired.

TRUE HIGH-TENSION MAGNETOS ARE SELF-CONTAINED

The true high-tension magneto differs from the pre-
ceding inasmuch as the current of high voltage is pro-
duced in the armature winding direct, without the use of
the separate coil. Instead of but one coil, the armature
carries two, one of comparatively coarse wire, the other
of many turns of finer wire. The arrangement of these

Fig. 62. Berling Double-Spark Independent System.

windings can be readily ascertained by reference to the
diagram B, Fig. 60, which shows the principle of opera-
tion very clearly. The simplicity of the ignition system
is evidently by inspection of Fig. 62. One end of the
primary winding (coarse wire) is coupled or grounded
to 'the armature core, and the other passes to the insu-
lated part of the interrupter. While in some forms the
interrupter or contact breaker mechanism does not re-
volve, the desired motion being imparted to the contact
lever to separate the points of a revolving cam, in this
the cam or tripping mechanism is stationary and the con-
tact breaker revolves. This arrangement makes it pos-
sible to conduct the current from the revolving primary
coil to the interrupter by a direct connection, eliminating

High Tension Magnetos Self -Contained 173

the use of brushes, which would otherwise be necessary.
In other forms of this appliance where the winding is
stationary, the interrupter may be operated by a revolv-
ing cam, though, if desired, the used of a brush at this
point will permit this construction with a revolving
winding.

During the revolution of the armature the grounded
lever makes and breaks contact with the insulated point,
short-circuiting the primary winding upon itself until the
armature reaches the proper position of maximum in-
tensity of current production, at which time the circuit is
broken, as in the former instance. One end of the sec-
ondary winding (fine wire) is grounded on the live end of
the primary, the other end being attached to the revolv-
ing arm of the distributor mechanism. So long as a closed
circuit is maintained feeble currents will pass through the
primary winding, and so long as the contact points are
together this condition will exist. When the current
reaches its maximum value, because of the armature be-
ing in the best position, the cam operates the interrupter
and the points are separated, breaking the short circuit
which has existed in the primary winding.

The secondary circuit has. been open while the distrib-
utor arm has moved from one contact to another and there
has been no flow of energy through this winding. While
the electrical pressure will rise in this, even if the dis-
tributor arm contacted with one of the segments, there
would be no spark at the plug until the contact points
separated, because the current in the secondary winding
would not be of sufficient strength. When the interrupter
operates, however, the maximum primary current will be
diverted from its short circuit and can flow to the ground
only through the secondary winding and spark-plug cir-
cuit. The high pressure now existing in the secondary
winding will be greatly increased by the sudden flow of
primary current, and energy of high enough potential to
successfully bridge the gap at the plug is thereby pro-
duced in the winding.

174

Aviation Engines

THE BERLING MAGNETO

The Berling magneto is a true high tension type de-
livering two impulses per revolution, but it is made in a
variety of forms, both single and double spark. Its prin-
ciple of action does not differ in essentials from the high

Fig. 63. Type DD Berling High Tension Magneto.

tension type previously described. This magneto is used
on Curtiss aviation engines and will deliver sparks in a
positive manner sufficient to insure ignition of engines up
to 200 horse-power and at rotative speeds of the magneto
armature up to 4,000 r. p. m. which is sufficient to take
care of an eight-cylinder V engine running up to 2,000

Berling Ignition Magneto 175

r. p. m. The magneto is driven at crank- shaft speed on
four-cylinder engines, at 1% times crank- shaft speed on six-
cylinder engines and at twice crank- shaft speed on eight-
cylinder V types. The types "D" and "DD" BER-
LING Magnetos are interchangeable with corresponding
magnetos of other standard makes. The dimensions of
the four-, six- and eight-cylinder types "D" and "DD"
are all the same.

The ideal method of driving the magneto is by means
of flexible direct connecting coupling to a shaft intended
for the purpose of driving the magneto. As the magneto
must be driven at a high speed, a coupling of some
flexibility is preferable. The employment of such a coup-
ling will facilitate the mounting of the magneto, because
a small inaccuracy in the lining up of the magneto with
the driving shaft will be taken care of by the flexible
coupling, whereas with a perfectly rigid coupling the:
line-up of the magneto must be absolutely accurate. An-
other advantage of the flexible coupling is that the vibra-
tion of the motor will not be as fully transmitted to the
armature shaft on the magneto as in case a rigid coup-
ling is used. This means prolonged life for the magneto.

The next best method of driving the magneto is by
means of a gear keyed to the armature shaft. When
this method of driving is employed, great care must be
exercised in providing sufficient clearance between the
gear on the magneto and the driving gear. If there
should be a tight spot between these two gears it will
react disadvantageously on the magneto. The third
available method is to drive the magneto by means of
a chain. This is the least desirable of the three methods
and should be resorted to only in case- of absolute neces-
sity. It is difficult to provide sufficient clearance when
using a chain without rendering the timing less accurate
and positive.

Fig. "64, A" shows diagrammtically the circuit of the
"D" type two-spark independent magneto and the switch
used with it. In position OFF the primary winding

176

Aviation Engines

of the magneto is short-circuited and in this position
the switch serves as an ordinary cut-out or grounding
switch. In position "1" the switch connects the mag-
neto in such a way that it operates as an ordinary
single-spark magneto. In this position one end of the

Distributor

Finger ^

^ Primary Circuit

Secondary "

Ground (Frame)

C^iL-V:' Condenser. \ . Interrupter

n fisfl n '.

Front View of Switch

Distributor
Finger-,

Magneto Interrupter'' ''Battery Timer
B

Back Vi'ew
of Switch

Fig. 64. Wiring 1 Diagrams of Berling Magneto Ignition Systems.

secondary winding is grounded to the body of the motor.
This is the starting position. In this position of the
switch the entire voltage generated in the magneto is
concentrated at one spark-plug instead of being divided
in half. With the. motor turning over very slowly, as is
the case in starting, the full voltage generated by the

Berling Ignition Magneto 177

magneto will not in all cases be sufficient to bridge simul-
taneously two spark gaps, but is amply sufficient to
bridge one. Also, this position of the switch tends to
retard the ignition and should be used in starting to
prevent back-firing. "With the switch in position "2"
the magneto applies ignition to both plugs in each
cylinder simultaneously. This is the normal running
position.

Fig. 64, B shows diagrammatically the circuit of the
type "DD" BERLING high-tension two-spark dual mag-
neto. This type is recommended for certain types of
heavy-duty airplane motors, which it is impossible to turn
over fast enough to give the magneto sufficient speed to
generate even a single spark of volume great enough to
ignite the gas in the cylinder. The dual feature consists
of .the addition to the magneto of a battery interrupter.
The equipment consists of the magneto, coil and special
high-tension switch. The coil is intended to operate on
six volts. Either a storage battery or dry cells may be
used.

With the switch in the OFF position, the magneto is
grounded, and the battery circuit is open. With the
switch in the second or battery position marked "BAT,"
one end of the secondary winding of the magneto is
grounded, and the magneto operates as a single-spark
magneto delivering high-tension current to the inside
distributor, and the battery circuit being closed the high-
tension current from the coil is delivered to the outside
distributor. In this position the battery current is sup-
plied to one set of spark plugs, no matter how slowly
the motor is turned over, but as soon as the motor starts,
the magneto supplies current as a single-spark magneto
to the other set of the spark-plugs. After the engine is
running, the switch should be thrown to the position
marked "MAG." The battery and coil are then dis-
connected, and the magneto furnishes ignition to both
plugs in each cylinder. This is the normal running
position. Either u non-vibrating coil type "N-l" is

178 Aviation Engines

furnished or a combined vibrating and non-vibrating coil
type "VN-1."

SETTING BERLING MAGNETO

The magneto may be set according to one of two
different methods, the selection of which is, to some
extent, governed by the characteristics of the engine,
but largely due to the personal preference on the part
of the user. In the first method described below, the
most advantageous position of the piston for fully ad-
vanced ignition is determined in relation to the extreme
advanced position of the magneto. In this case, the
fully retarded ignition will not be a matter of selection,
but the timing range of the magneto is wide enough to
bring the fully retarded ignition after top-center position
of the piston. The second method for the setting of the
magneto fixes the fully retarded position of the magneto
in relation to that position of the piston where fully
retarded ignition is desired. In this case, the extreme
advance position of the magneto will not always corre-
spond with the best position of the piston for fully ad-
vanced ignition, and the amount of advance the magneto
should have to meet ideal requirements in this respect
must be determined by experiment.

First Method:

1. Designate one cylinder as cylinder No. 1.

2. Turn the crank-shaft until the piston in cylinder
No. 1 is in the position where the fully advanced spark
is desired to occur.

3. Eemove the cover from the distributor block and
turn the armature shaft in the direction of rotation of the
magneto until the distributor finger-brush comes into
such a position that this brush makes contact with the
segment which is connected to the cable terminal marked
"1." This is either one of the two bottom segments,
depending upon the direction of rotation.

4. Place the cam housing in extreme advance, i.e.,

Timing Berling Magneto 179

turn the cam housing until it stops, in the direction
opposite to the direction of rotation of the armature.
With the cam housing in this position, open the cover.

5. "With the armature in the approximate position as
described in "3," turn the armature slightly in either
direction to such a point that the platinum points of the
magneto interrupter will just begin to open at the end
of the cam, adjacent to the fibre lever on the interrupter.

6. With this exact position of the armature, fix the
magneto to the driving member of the engine.

Second Method:

1. Designate one cylinder as cylinder No. 1.

2. Turn the crank-shaft until the piston in cylinder
No. 1 is in the position at which the fully retarded spark
is desired to occur.

3. Same as No. 3 under First Method.

4. Place the cam housing in extreme retard, i.e., turn
the cam housing until it stops, in the same direction as
the direction of rotation of the armature. With the cam
housing in this position, open the cover.

5. Same as No. 5 under First Method.

6. Same as No. 6 under First Method.

WIRING THE MAGNETO

The wiring of the magneto is clearly shown by wiring
diagram.

First determine the sequence of firing for the cylinders
and then connect the cables to the spark plug in the
cylinders in proper sequence, beginning with cylinder
No. 1 marked on the distributor block.

The switch used with the independent type must be
mounted in such a manner that there will be a metallic
connection between the frame of the magneto and the
metal portion of the switch.

It is advisable to use a separate battery, either storage
or dry cells, as a source of current for the dual equip-

180 Aviation Engines

ment. Connecting to the same battery that is used with
the generator and other electrical equipment may cause
trouble, as a "ground" in this battery causes the coil
to overheat.

CARE AND MAINTENANCE

Lubrication:

Use only the very best of oil for the oil cups.

Put five drops of oil in the oil cup at the driving end
of the magneto for every fifty hours of actual running.

Put five drops of oil in the oil cup at the interrupter
end of the magneto, located at one side of. the cam
housing, for every hundred hours of actual running.

Lubricate the embossed cams in the cam housing with
a thin film of vaseline every fifty hours of actual run-
ning. Wipe off all superfluous vaseline. Never use oil
in the interrupter. Do not lubricate any other part of
the interrupter.

Adjusting the Interrupter:

With the fibre lever in the center of one of the em-
bossed cams, as at Fig. 65, the opening between the
platinum contacts should be not less than .016" and not
more than .020". The gauge riveted to the adjusting
wrench should barely be able to pass between the con-
tacts when fully open. The platinum contacts must be
smoothed off with a very fine file. When in closed posi-
tion, the platinum contacts should make contact with
each other over their entire surfaces.

When inspecting the interrupter, make sure that the
ground brush in the back of the interrupter base is
making good contact with the surface on which it rubs.

Cleaning the Distributor:

The distributor block cover should be removed for
inspection every twenty-five hours of actual running
and the carbon deposit from the distributor finger-brush
wiped off the distributor block by rubbing with a rag

Locating Magneto Trouble

181

or piece of waste dipped in gasoline or kerosene. The
high-tension terminal brush on the side of the magneto
should also be carefully inspected for proper tension.

LOCATING TKOTJBLE

Trouble in the ignition system is indicated by the
motor " missing, " stopping entirely, or by inability to
start.

It is safe to assume that the trouble is not in the

Lev er Retaining
5 p ring.

.Com

Contact Points
Separated-

Fibre

Interrupter
Lever

Contact Breaker'*
Housing

"----Cam

Fig. 65. The Berling Magneto Breaker Box Showing Contact Points
Separated and Interrupter Lever on Cam.

magneto, and the carburetor, gasoline supply and spark-
plugs should first be investigated.

If the magneto is suspected, the first thing to do is
to determine if it will deliver a spark. To determine
this, disconnect one of the high-tension leads from the
spark-plug in one of the cylinders and place it so that
there is approximately Vie" between the terminal and
the cylinder frame.

Open the pet cocks on the other cylinders to prevent
the engine from firing and turn over the engine until
the piston is approaching the end of the compression

182 Aviation Engines

stroke in the cylinder from which the cable has been
removed. Set the magneto in the advance position and
rapidly rock the engine over the top-center position,
observing closely if a spark occurs between the end of
the high-tension cable and the frame.

If the magneto is of the dual type, the trouble may
be either in the magneto or in the battery or coil system,
therefore disconnect the battery and .place the switch
in the position marked "MAG." The magneto will then
operate as an independent magneto and should spark
in the proper manner. After this the battery system
should be investigated. To test the operation of the
battery and coil, examine all connections, making sure
that they are clean and tight, and then with the switch
in the "BAT," rock the piston slowly back and forth.
If a type "VN-1" coil is used, a shower of sparks should
jump between the high-tension cable terminal and the
cylinder frame when the piston is in the correct position
for firing. If no spark occurs, remove the cover from
the coil and see that the vibrating tongue is free. If a
type "N-l" coil is used, a single spark will occur. The
battery should furnish six volts when connected to the
coil, and this should also be verified.

If the coil still refuses to give a spark and all con-
nections are correct, the coil should be replaced and the
defective coil returned to the manufacturer.

If both magneto and coil give a spark when tested
as just described, the spark-plugs should be investi-
gated. To do this, disconnect the cables and remove
the spark-plugs. Then reconnect the cables to the plugs
and place them so that the frame portions of the plugs
are in metallic connection with the frame of the motor.
Then turn over the motor, thus revolving the magneto
armature, and see if a spark is produced at the spark
gaps of the plugs.

The most common defects in spark-plugs are breaking
down of the insulation, fouling due to carbon, or too large
or small a spark gap. To clean the plugs a stiff brush

Locating Magneto Trouble

183

and gasoline should be used. The spark gap should be
about % 2 " and never less than % 4 ". Too small a gap
may have been caused by beads of metal forming due
to the heat of the spark. Too long a gap may have been
caused by the points burning off.

If the magneto and spark plugs are in good condition
and the engine does not run satisfactorily, the setting

-Distributor

Cover

Contaci-
Brectker

Rocking Field''

Fig. 66. The Dixie Model 60 for Six-Cylinder Airplane Engine Ignition.

should be verified according to instructions previously
given, and, if necessary, readjusted.

Be careful to observe that both the type "VN-1" and
type "N-l" coils are so arranged that the spark occurs
on the opening of the contacts of the timer. As this is
just the reverse of the usual operation, it should be care-
fully noted when any change in the setting of the timer
is made. The timer on the dual type magneto is ad-
justed so that the battery spark occurs about 5 later

184

Aviation Engines

than the magneto spark. This provides an automatic
advance as soon as the switch is thrown to the magneto
position "MAG." This relative timing can be easily
adjusted by removing the interrupter and shifting the
cam in the direction desired.

THE DIXIE MAGNETO

The Dixie magneto, shown at Fig. 66, operates on a
different principle than the rotary armature type. It is
used on the Hall-Scott and other aviation engines. In

(4) ?. lbT.i(. V.j Deep D S. St'd. Thread*

Fig. 67. Installation Dimensions of Dixie Model 60 Magneto.

this magneto the rotating member consists of two pieces
of magnetic material separated by a non-magnetic center
piece. This member constitutes true rotating poles for
the magnet and rotates in a field structure, composed of
two laminated field pieces, riveted between two non-
magnetic rings. The bearings for the rotating poles are

Dixie Ignition Magneto

185

mounted in steel plates, which lie against the poles of the
magnets. When the magnet poles rotate, the magnetic
lines of force from each magnet pole are carried directly

Ma q n ets .>

Rotating
Magnet Poles ..,__

.Inductor

Drive Shaft

Inductor Shaft^

: --Inductors or Magnet Poles

Plates and Bearings

The rotating element of the, Dixie magneto. In the Dixie
there are no revolving winding$,there is no moving wire
and the parts of the magneto are reduced to a minimum.

A.G. HAGSTROMN.Y.

Fig. 68. The Rotating Elements of the Dixie Magneto.

to the field pieces and through the windings, without
reversal through the mass of the rotating member and
with only a single air gap. There are no losses by flux
reversal in the rotating part, such as take place in other

186 Aviation Engines

machines, and this is said to account for the high efficiency
of the instrument.

And this "Mason Principle '' involved in the operation
of the Dixie is simplified by a glance at the field struc-
ture, consisting of the non-magnetic rings, assembled to
which are the field pieces between which the rotating
poles revolve (see Fig. 68). Eotating between the
limbs of the magnets, these two pieces of magnetic mate-
rial form true extensions to the poles of the magnets,
and are, in consequence, always of the same polarity.
It will be seen there is no reversal of the magnetism
through them, and consequently no eddy current or hys-
teresis losses which are present in the usual rotor or
inductor types. The simplicity features of construction
stand out prominently here, in that there are no revolving
windings, a detail entirely differing from the orthodox
high-tension instrument. This simplicity becomes in-
stantly apparent when it is found that the circuit breaker,
instead of revolving as it does in other types, is stationary
and that the whole breaker mechanism is exposed by
simply turning the cover spring aside and removing
cover. This makes inspection and adjustment particu-
larly simple, and the fact that no special tool is neces-
sary for adjustment of the platinum points an ordinary
small screw-driver is the whole "kit of tools" needed in
the work of disassembling or assembling is a feature of
some value.

With dust- and water-protecting casing removed, and
one of the magnets withdrawn, as in Fig. 69, the winding
can be seen with its core resting on the field pole pieces
and the primary lead attached to its side. An important
feature of the high-tension winding is that the heads are
of insulating material, and there is not the tendency for
the high-tension current to jump to the side as in the
ordinary armature type magneto. The high-tension cur-
rent is carried to the distributor by means of an insulated
block with a spindle, at one end of which is a spring
brush bearing directly on the winding, thus shortening

Dixie Ignition Magneto

187

the path -of the high-tension current and eliminating the
use of rubber spools and insulating parts. The moving
parts of the magneto need never be disturbed if the high-
tension winding is to be removed. This winding con-

Distributor
Cover

Terminals,
to Plugs ;

Contact \ \
Box J

.''Cover Retaining
Screws

-Cover ^ rng

The whole breaker mechanism is exposed by
simply turning the cover spring aside and
removing cover. A screw driver is the only
tool necessary to adjust the platinum points.

Distributor
Drive Gear

Distributor Cover
\.

Distributor

Brush

Carrier,

Nothing could be simpler than Dixie con-
struction. By loosening nuts and turning
clamps aside, the distributor block can be
removed and distributor disc lifted
out of its housing.

Tension
Winding

After removing the cover the
magnets can be taken off-exposing
the high iension winding.

;' Teasion

Condenser.

By taking out four screws the con-
denser and high tension winding
can be readily removed.

AG.HSSTROM N.1

Fig. 69. Suggestions for Adjusting and Dismantling Dixie Magneto. A
Screw Driver Adjusts Contact Points. B Distributor Block Removed.
C Taking off Magnets. D Showing How Easily Condenser and High.
Tension Windings are Removed.

stitutes all of the magneto windings, no external spark
coil being necessary. The condenser is placed directly
above the winding and is easily removable by taking out
two screws, instead of being placed in an armature where
it is inaccessible except to an expert, and where it cannot
be replaced except at the factory whence it emanated.

188 Aviation Engines

CARE OF THE DIXIE MAGNETO

The bearings of the magneto are provided with oil
cups and a few drops of light oil every 1,000 miles are
sufficient. The breaker lever should be lubricated every
1,000 miles with a drop of light oil, applied with a tooth-
pick. The proper distance between the platinum points
when separated should not exceed .020 or one-fiftieth of
an inch. A gauge of the proper size is attached to the
screwdriver furnished with the magneto. The platinum
contacts should be kept clean and properly adjusted.
Should the contacts become pitted, a fine file should be
used to smooth them in order to permit them to come
into perfect contact. The distributor block should be
removed occasionally and inspected for an accumulation
of carbon dust. The inside of the distributor block should
be cleaned with a cloth moistened with gasoline and
then wiped dry with a clean cloth. When replacing the
block, care must be exercised in pushing the carbon brush
into the socket. Do not pull out the carbon brushes in the
distributor because you think there is not enough tension
on the small brass springs. In order to obtain the most
efficient results, the normal setting of the spark-plug
points should not exceed .025 of an inch, and it is ad-
visable to have the gap just right before a spark-plug is
inserted.

The spark-plug electrodes may be easily set by means
of the gauge attached to the screwdriver. The setting
of the spark-plug points is an important function ivhich
is usually overlooked, with the result that the magneto
is blamed when it is not at fault.

TIMING OF THE DIXIE MAGNETO

In order to obtain the utmost efficiency from the en-
gine, the magneto must be correctly timed to it. This
operation is usually performed when the magneto is fitted
to the engine at the factory. The correct setting may
vary according to individuality of the engine, and some

Timing of .the Dixie Magneto

189

190 Aviation Engines

engines may require an earlier setting in order to obtain
the best results. However, should the occasion arise to
retime the magneto, the procedure is as follows: Kotate
the crank-shaft of the engine until one of the pistons,
preferably that of cylinder No. 1, is Me of an inch ahead
of the end of the compression stroke. With the timing
lever in full retard position, the driving shaft of the
magneto should be rotated in the direction in which it
will be driven. The circuit breaker should be closely
observed and when the platinum contact points are about
to separate, the drive gear or coupling should be secured
to the drive shaft of the magneto. Care should be taken
not to alter the position of the magneto shaft when
tightening the nut to secure the gear or coupling, after
which the magneto should be secured to its base. Re-
move the distributor block and determine which terminal
of the block is in contact with the carbon brush of the
distributor finger and connect with plug wire leading to
No. 1 cylinder to this terminal. Connect the remaining
plug wires in turn according to the proper sequence of
firing of the cylinders. (See the wiring diagram for a
typical six-cylinder engine at Fig. 70.) A terminal on
the end of the cover spring of the magneto is provided
for the purpose of connecting the wire leading to a ground
switch for stopping the engine.

A special model or type of magneto is made for
V engines which use a compound distributor construc-
tion instead of the simple type on the model illustrated
and a different interior arrangement permits the pro-
duction of four sparks per revolution of the rotors. This
makes it possible to run the magneto slower than would
be possible with the two-spark form. The application
of two compound distributor magnetos of this type to a
Thomas-Morse 135 horse-power motor of the eight-cylin-
der V pattern is clearly shown at Fig. 71.

191

192

Aviation Engines

SPARK-PLUG DESIGN AND APPLICATION

With the high-tension system of ignition the spark is
produced by a current of high voltage jumping between
two points which break the complete circuit, which would
exist otherwise in the secondary coil and its external
connections. The spark-plug is a simple device which

Air Starter
\Pipe$

Water Pump

Ignition
Cables

Compound
Distributor
Magneto

Oil Pump

\ Ignition
-> r^^in

bles

Compound
Distributor
Maqneto

Fig. 71. How Magneto Ignition is Installed on Thomas-Morse 135 Horse-
Power Motor.

Spark-Plug Design and Application

193

consists of two terminal electrodes carried in a suitable
shell member, which is screwed into the cylinder. Typical
spark-plugs are shown in section at Fig. 72 and the
construction can be easily understood. The secondary
wire from the coil is attached to a terminal at the top
of a central electrode member, which is supported in a
bushing of some form of insulating material. The type
shown at A employs a molded porcelain as an insulator,
while that depicted at B uses a bushing of mica. The

Asbestos
Packing

I "I <ff Standard

Thread

[ *3f Solid Nickel Hod

Spark PoMt

Fig. 72. Spark-Plug Types Showing Construction and Arrangement

of Parts.

insulating bushing and electrode are housed in a steel
body, which is provided with a screw thread at the bot-
tom, by which means it is screwed into the combustion
chamber.

When porcelain is used as an insulating material it is
kept from direct contact with the metal portion by some
form of yielding packing, usually asbestos. This is nec-
essary because the steel and porcelain have different
coefficients of expansion and some flexibility must be
provided at the joints to permit the materials to expand
differently when heated. The steel body of the plug which
is screwed into the cylinder is in metallic contact with it
and carries sparking points which form one of the ter-
minals of the air gap over which the spark occurs. The

194 Aviation Engines

current entering at the top of the plug cannot reach the
ground, which is represented by the metal portion of the
engine, until it has traversed the full length of the cen-
tral electrode and overcome the resistance of the gap
between it and the terminal point on the shell. The
porcelain bushing is firmly seated against the asbestos
packing by means of a brass screw gland which sets
against a flange formed on the porcelain, and which
screws into a thread at the upper portion of the plug
body.

The mica plug shown at B is somewhat simpler in
construction than that shown at A. The mica core which
keeps the central electrode separated from the steel body
is composed of several layers of pure sheet mica wound
around the steel rod longitudinally, and hundreds of
stamped steel washers which are forced over this member
and compacted under high pressure with some form of a
binding material between them. Porcelain insulators are
usually molded from high-grade clay and are approxi-
mately of the shapes desired by the designers of the plug.
The central electrode may be held in place by mechanical
means such as nuts, packings, and a shoulder on the rod,
as shown at A. Another method sometimes used is to
cement the electrode in place by means of some form of
fire-clay cement. Whatever method of fastening is used,
it is imperative that the joints be absolutely tight so that
no gas can escape at the time of explosion. Porcelain
is the material most widely used because it can be glazed
eo that it will not absorb oil, and it is subjected to such
high temperature in baking that it is not liable to crack
when heated.

The spark-plugs may be screwed into any convenient
part of the combustion chamber, the general practice
being to install them in the caps over the inlet valves,
or in the side of the combustion chamber, so the points
will be directly in the path of the entering fresh gases
from the carburetor.

Other insulating materials sometimes used are glass,

Spark-Plug Design and Use

195

steatite (which is a form of soapstone) and lava. Mica
and porcelain are the two common materials used because
they give the best results. Glass is liable to crack, while
lava or the soapstone insulating bushings absorb oil.
The spark gap of the average plug is equal to about
%2 of an inch for coil ignition and %o of an inch when
used in magneto circuits. A simple gauge for determi-
ning the gap setting is the thickness of an ordinary visiting

23/4" Max.
70 mm-

#8-32 \.
4mm. . 7 5 p.)

Across Flats

16.9 Threads per inch : 1.5 millimeters pitch
Root diameter 633 inch.: 16.09 millimeters
Pitch diameter 678* inch : 17.22 +02 millimeters
Outside diameter 7/7 inch 18. 2 millimeters

Fig. 73. Standard Airplane Engine Plug Suggested "by S. A. E. Standards

Committee.

card for magneto plugs, or a space equal to the thickness
of a worn dime for a coil plug. The insulating bushings
are made in a number of different ways, and while de-
tails of construction vary, spark-plugs do not differ essen-
tially in design. The dimensions of the standardized plug
recommended by the S. A. E. are shown at Fig. 73.

It is often desirable to have a water-tight joint be-
tween the high-tension cable and the terminal screw on
top of the insulating bushing of the spark-plug, especially
in marine applications. The plug shown at C, Fig. 72,

196 Aviation Engines

is provided with an insulating member or hood of porce-
lain, which is secured by a clip in such a manner that it
makes a water-tight connection. Should the porcelain
of a conventional form of plug become covered with
water or dirty oil, the high-tension current is apt to
run down this conducting material on the porcelain and
reach the ground without having to complete its circuit
by jumping the air gap and producing a spark. It will
be evident that wherever a plug is exposed to the ele-
ments, which is often the case in airplane service, that it
should be protected by an insulating hood which will keep
the insulator dry and prevent short circuiting of the
spark. The same end can be attained by slipping an
ordinary rubber nipple over the porcelain insulator of
any conventional plug and bringing up one end over the
cable.

TWO-SPARK IGNITION

On most aviation engines, especially those having large
cylinders, it is sometimes difficult to secure complete
combustion by using a single-spark plug. If the com-
bustion is not rapid the efficiency of the engine will be
reduced proportionately. The compressed charge in the
cylinder does not ignite all at once or instantaneously,
as many assume, but it is the strata of gas nearest the
plug which is. ignited first. This in turn sets fire to
consecutive layers of the charge until the entire mass
is aflame. One may compare the combustion of gas in
the gas-engine cylinder to the phenomenon which obtains
when a heavy object is thrown into a pool of still water.
First a small circle is seen at the point where the object
has passed into the water, this circle in turn inducing
other and larger circles until the whole surface of the
pool has been agitated from the .one central point. The
method of igniting the gas is very similar, as the spark
ignites the circle of gas immediately adjacent to the
sparking point, and this circle in turn ignites a little
larger one concentric with it. The second circle of flame

Two- Spark Ignition 197

sets fire to more of the gas, and finally the entire con-
tents of the combustion chamber are burning.

While ordinarily combustion is sufficiently rapid with
a single plug so that the proper explosion is obtained at
moderate engine speeds, if the engine is working fast and
the cylinders are of large capacity more power may be
obtained by setting fire to the mixture at two different
points instead of but one. This may be accomplished by
using two sparking-plugs in the cylinder instead of one,
and experiments have shown that it is possible to gain
from twenty-five to thirty per cent, in motor power at
high speed with two-spark plugs, because the combustion
of gas is accelerated by igniting the gas simultaneously
in two places. The double-plug system on airplane en-
gines is also a safeguard, as in event of failure of one
plug in the cylinder the other would continue to fire the
gas, and the engine will continue to function properly.

In using magneto ignition some precautions are neces-
sary relating to wiring and also the character of the spark-
plugs employed. The conductor should be of good quality,
have ample insulation, and be well protected from accu-
mulations of oil, which would tend to decompose rubber
insulation. It is customary to protect the wiring by run-
ning it through the conduits of fiber or metal tubing lined
with insulating material. Multiple strand cables should
be used for both primary and secondary wiring, and the
insulation should be of rubber at least %6 inch thick.

The spark-plugs commonly used for battery and coil
ignition cannot always be employed when a magneto is
fitted. The current produced by the mechanical generator
has a greater amperage and more heat value than that
obtained from transformer coils excited by battery cur-
rent. The greater heat may burn or fuse the slender
points used on some battery plugs and heavier electrodes
are needed to resist the heating effect of the more intense
arc. While the current has greater amperage it is not of
as high potential or voltage as that commonly produced
by the secondary winding of an induction coil, and it

198

Aviation Engines

cannot overcome as much of a gap. Manufacturers of
magneto plugs usually set the spark points about %4 of
an inch apart. The most efficient magneto plug has a
plurality of points so that when the distance between one
set becomes too great the spark will take place between

p..

Fig. 74. Special Mica Plug for Aviation Engines.

one of the other pairs of electrodes which are not sep-
arated by so great an air space.

SPECIAL PLUGS FOR AIRPLANE WORK

Airplane work calls for special construction of spark-
plugs, owing to the high compression used in the engines
and the fact that they are operated on open throttle prac-
tically all the time, thus causing a great deal of heat to

Special Airplane Engine Plugs 199

be developed. The plug shown at Fig. 74 was recently
described in "The Automobile," and has been devised
especially for airplane engines and automobile racing
power plants. The core C is built up of mica washers,
and has square shoulders. As mica washers of different
sizes may be used, and accurate machining, such as is nec-
essary with conical clamping surfaces, is not required,
the plug can be produced economically. The square
shoulders of the core afford two gasket seats, and when
the core is clamped in the shell by means of check nut E,
it is accurately centered and a tight joint is formed. This
construction also makes a shorter plug than where coni-
cal fits are used, thus improving the heat radiation through
the stem. The lower end of the shell is provided with a
baffle plate 0, which tends to keep the oil away from the
mica. There are perforations L in this baffle plate to
prevent burnt gases being pocketed behind the baffle plate
and pre-igniting the new charge. This construction also
brings the firing point out into the firing chamber of the
engine, and has all the other advantages of a closed-end
plug. The stem P is made of brass or copper, on account
of their superior heat conductivity, and the electrode J
is swedged into the bottom of the stem, as shown at K,
in a secure manner.

The shell is finned, as shown at G, to provide greater
heat radiating surface. There is also a fin F at the top
of the stem, to increase the radiation of heat from the
stem and electrode. The top of this finned portion is
slightly countersunk, and the stem is riveted into same,
thereby reducing the possibility of leakage past the
threads on the stem. This finned portion is necked at A
to take a slip terminal.

In building up the core a small section of washers, I,
is built up before the mica insulating tube D is placed on.
This construction gives a better support to section L
Baffle plate is bored out to allow the electrode J to
pass through, and the clearance between baffle plate and
electrode is made larger than the width of the gap be-

200 Aviation Engines

tween the firing points, so that there is no danger of the
spark jumping from the electrode to the baffle plate.

This plug will be furnished either with or without the
finned portion, to meet individual requirements. The
manufacturers lay special stress upon the simplicity of
construction and upon the method of clamping, which is
claimed to make the plug absolutely gas-tight.

CHAPTER VII

Why Lubrication Is Necessary Friction Defined Theory of Lubrica-
tion Derivation of Lubricants Properties of Cylinder Oils
Factors Influencing Lubrication System Selection Gnome Type
Engines Use Castor Oil Hall-Scott Lubrication System Oil Sup-
ply by Constant Level Splash System Dry Crank-Case System Best
for Airplane Engines Why Cooling Systems Are Necessary
Cooling Systems Generally Applied Cooling by Positive Pump
Circulation Thermo-Syphon System Direct Air-Cooling Methods
Air-Cooled Engine Design Considerations.

WHY LUBRICATION IS NECESSARY

THE importance of minimizing friction at the various
bearing surfaces of machines to secure mechanical effi-
ciency is fully recognized by all mechanics, and proper
lubricity of all parts of the mechanism is a very essential
factor upon which the durability and successful operation
of the motor car power plant depends. All of the moving
members of the engine which are in contact with other
portions, whether the motion is continuous or intermit-
tent, of high or low velocity, or of rectilinear or continued
rotary nature, should be provided with an adequate sup-
ply of oil. No other assemblage of mechanism is operated
under conditions which are so much to its disadvantage
as the motor car, and the tendency is toward a simplifica-
tion of oiling methods so that the supply will be ample
and automatically applied to the points needing it.

In all machinery in motion the members which are in
contact have a tendency to stick to each other, and the
very minute projections which exist on even the smooth-
est of surfaces would have a tendency to cling or adhere '
to each other if the surfaces were not kept apart by some
elastic and unctuous substance. This will flow or spread
out over the surfaces and smooth out the inequalities

201

202 Aviation Engines

ing which tend to produce heat and retard motion of the
pieces relative to each other.

A general impression which obtains is that well ma-
chined surfaces are smooth, but while they are apparently
free from roughness, and no projections are visible to the
naked eye, any smooth bearing surface, even if very care-
fully ground, will have a rough appearance if examined
with a magnifying glass. An exaggerated condition to
illustrate this point is shown at Fig. 75. The amount of
friction will vary in proportion to the pressure on the
surfaces in contact and will augment as the loads in-
crease; the rougher surfaces will have more friction than
smoother ones and soft bodies will produce more friction
than hard substances.

FRICTION DEFINED

Friction is always present in any mechanism as a re-
sisting force that tends to retard motion and bring all
moving parts to a state of rest. The absorption of power
by friction may be gauged by the amount of heat which
exists at the bearing points. Friction of solids may be
divided into two classes: sliding friction, such as exists
between the piston and cylinder, or the bearings of a
gas-engine, and rolling friction, which is that present
when the load is supported by ball or roller bearings, or
that which exists between the tires or the driving wheels
and the road. Engineers endeavor to keep friction losses
as low as possible, and much care is taken in all modern
airplane engines to provide adequate methods of lubrica-
tion, or anti-friction bearings at all points where con-
siderable friction exists.

THEORY OF LUBRICATION

The reason a lubricant is supplied to bearing points
will be easily understood if one considers that these
elastic substances flow between the close fitting surfaces,
and fcy filling up the minute depressions in the surfaces
and covering the high spots act as a cushion which

Theory of Lubrication

203

absorbs the heat generated and takes the wear instead
of the metallic bearing surface. The closer the parts fit
together the more fluid the lubricant must be to pass
between their surfaces, and at the same time it must
possess sufficient body so that it will not be entirely
forced out by the pressure existing between the parts.

Oils should have good adhesive, as well as cohesive,
qualities. The former are necessary so that the oil film

Pillow Block

Magnified
Shaft

Magnifying Glass

Fig. 75. Showing Use of Magnifying Glass to Demonstrate that Apparently
Smooth Metal Surfaces May Have Minute Irregularities which Produce
Friction.

will cling well to the surfaces of the bearings; the latter,
so the oil particles will cling together and resist the ten-
dency to separation which exists all the time the bearings
are in operation. When used for gas-engine lubrication
the oil should be capable of withstanding considerable
heat in order that it will not be vaporized by the hot por-
tions of the cylinder. It should have sufficient cold test
so that it will remain fluid and flow readily at low tem-
perature. Lubricants should be free from acid, or alka-

204 Aviation Engines

lies, which tend to produce a chemical action with metals
and result in corrosion of the parts to which they are
applied. It is imperative that the oil be exactly the
proper quality and nature for the' purpose intended and
that it be applied in a positive manner. The requirements
may be briefly summarized as follows :

First It must have sufficient body to prevent seizing
of the parts v to which it is applied and between which it
is depended upon to maintain an elastic film, and yet it
must not have too much viscosity, in order to minimize
the internal or fluid friction which exists between the
particles of the lubricant itself.

Second The lubricant must not coagulate or gum;
must not injure the parts to which it is applied, either by
chemical action or by producing injurious deposits, and
it should not evaporate readily.

Third The character of the work will demand that
the oil should not vaporize when heated or thicken to such
a point that it will not flow readily when cold.

Fourth The oil must be free from acid, alkalies, ani-
mal or vegetable fillers, or other injurious agencies.

Fifth It must be carefully selected for the work re-
quired and should be a good conductor of heat.

DERIVATION OF LUBRICANTS

The first oils which were used for lubricating machin-
ery were obtained from animal and vegetable sources,
though at the present time most unguents are of mineral
derivation. Lubricants may exist as fluids, semifluids, or
solids. The viscosity will vary from light spindle or
dynamo oils, which have but little more body than kero-
sene, to the heaviest greases and tallows. The most com-
mon solid employed as a lubricant is graphite, sometimes
termed " plumbago" or " black lead." This substance is
of mineral derivation.

The disadvantage of oils of organic origin, such as
those obtained from animal fats or vegetable substances,
is that they will absorb oxygen from the atmosphere,

Derivation of Lubricants 205

which causes them to thicken or become rancid. Such
oils have a very poor cold test, as they solidify at com-
paratively high temperatures, and their flashing point is
so low that they cannot be used at points where much
heat exists. In most animal oils various acids are present
in greater or less quantities, and for this reason they are
not well adapted for lubricating metallic surfaces which
may be raised high enough in temperature to cause de-
composition of the oils.

Lubricants derived from the crude petroleum are
called ' ' Oleonaphthas ' ' and they are a product of the
process of refining petroleum through which gasoline and
kerosene are obtained. They are of lower cost than vege-
table or animal oil, and as they are of non-organic origin,
they do not become rancid or gummy by constant expo-
sure to the air, and they will have no corrosive action
on metals because they contain no deleterious substances
in chemical composition. By the process of fractional
distillation mineral oils of all grades can be obtained.
They have a lower cold and higher flash test and there
is not the liability of spontaneous combustion that exists
with animal oils.

The organic oils are derived from fatty substances,
which are present in the bodies of all animals and in
some portions of plants. The general method of extract-
ing oil from animal bodies is by a rendering process,
which consists of applying sufficient heat to liquefy the
oil and then separating it from the tissue with which it
is combined by compression. The only oil which is used
to any extent in gas-engine lubrication that is not of
mineral derivation is castor oil. This substance has been
used on high-speed racing automobile engines and on
airplane power plants. It is obtained from the seeds of
the castor plant, which contain a large percentage of oil.

Among the solid substances which may be used for
lubricating purposes may be mentioned tallow, which is
obtained from the fat of animals, and graphite and soap-
stone, which are of mineral derivation. Tallow is never

206 Aviation Engines

used at points where it will be exposed to much heat,
though it is often employed as a filler for greases used
in transmission gearing of autos. Graphite is sometimes
mixed with oil and applied to cylinder lubrication, though
it is most often used in connection with greases in the
landing gear parts and for coating wires and cables of
the airplane. Graphite is not affected by heat, cold, acids,
or alkalies, and has a strong attraction for metal surfaces.
It mixes readily with oils and greases and increases their
efficiency in many applications. It is sometimes used
where it would not be possible to use other lubricants
because of extremes of temperature.

The oils used for cylinder lubrication are obtained
almost exclusively from crude petroleum derived from
American wells. Special care must be taken in the selec-
tion of crude material, as every variety will not yield oil
of the proper quality to be used as a cylinder lubricant.
The crude petroleum is distilled as rapidly as possible
with fire heat to vaporize off the naphthas and the burn-
ing oils. After these vapors have been given off super-
heated steam is provided to assist in distilling. When
enough of the light elements have been eliminated the
residue is drawn off, passed through a strainer to free
it from grit and earthy matters, and is afterwards cooled
to separate the wax from it. This is the dark cylinder oil
and is the grade usually used for steam-engine cylinders.

PROPERTIES OF CYLINDER OILS

The oil that is to be used in the gasoline engine must
be of high quality, and for that reason the best grades
are distilled in a vacuum that the light distillates may be
separated at much lower temperatures than ordinary
conditions of distilling permit. If the degree of heat
is not high the product is not so apt to decompose and
deposit carbon. If it is desired 'to remove the color of
the oil which is caused by free carbon and other impurities
it can be accomplished by filtering the oil through char-
coal. The greater the number of times the oil is filtered,

Properties of 'Cylinder Oils 207

the lighter it will become in color. The best cylinder
oils have flash points usually in excess of 500 degrees F.,
and while they have a high degree of viscosity at 100
degrees F. they become more fluid as the temperature
increases.

The lubricating oils obtained by refining crude petro-
leum may be divided into three classes:

First The natural oils of great body which are pre-
pared for use by allowing the crude material to settle
in tanks at high temperature and from which the im-
purities are removed by natural filtration. These oils are
given the necessary body and are free from the volatile
substances they contain by means of superheated steam
which provides a source of heat.

Second Another grade of these natural oils which are
filtered again at high temperatures and under pressure
through beds of animal charcoal to improve their color.

Third Pale, limpid oils, obtained by distillation and
subsequent chemical treatment from the residuum pro-
duced in refining petroleum to obtain the fuel oils.

Authorities agree that any form of mixed oil in which
animal and mineral lubricants are combined should never
be used in the cylinder of a gas engine as the admixture
of the lubricants does not prevent the decomposition of
the organic oil into the glycerides and fatty acids peculiar
to the fat used. In a gas-engine cylinder the flame tends
to produce more or less charring. The deposits of carbon
will be much greater with animal oils than with those
derived from the petroleum base because the constituents
of a fat or tallow are not of the same volatile character
as those which comprise the hydro-carbon oils which will
evaporate or volatilize before they char in most instances.

FACTORS INFLUENCING LUBRICATION SYSTEM SELECTION

The suitability of oil for the proper and efficient lubri-
cation of all internal combustion engines is determined
chiefly by the following factors:

208 Aviation Engines

1. Type of cooling system (operating temperatures).

2. Type of lubricating system (method of applying
oil to the moving parts).

3. Eubbing speeds of contact surfaces.

Were the operating temperatures, bearing surface
speeds and lubrication systems identical, a single oil
could be used in all engines with equal satisfaction. The
only change then necessary in viscosity would be that due
to climatic conditions. .As engines are now designed, only
three grades of oil are necessary for the lubrication of
all types with the exception of Knight, air-cooled and
some engines which run continuously at full load. In the
specification of engine lubricants the feature of load
carried by the engine should be carefully considered.

Full Load Engines.

1. Marine.

2. Kacing automobile.

3. Aviation.

4. Farm tractor.

5. Some stationary.

Variable Load Engines.

1. Pleasure automobile.

2. Commercial vehicle.

3. Motor cycle.

4. Some stationary.

Of the forms outlined, the only one we have any
immediate concern about is the airplane power plant.
The Platt & Washburn Kenning Company, who have
made a careful study of the lubrication problem as ap-
plied to 'all types of engines, have found a peculiar set
of conditions to apply to oiling high-speed constant-duty
or "full-load" engines. Modern airplane engines are
designed to operate continuously at a fairly uniform
high rotative speed and at full load over long periods
of time. As a sequence to this heavy duty the operating

Lubricating Airplane Engines 209

temperatures are elevated. For the sake of extreme light-
ness in weight of all parts, very thin alloy steel aluminum
or cast iron pistons are fitted and the temperature of
the thin piston heads at the center reaches anywhere
between 600 and 1,400 Fahr., as in automobile racing
engines. Freely exposed to such intense heat hydro-carbon
oils are partially "cracked" into light and heavy prod-
ucts or polymerized into solid hydro-carbons. From these
facts it follows that only heavy mineral oils of low carbon
residue and of the greatest chemical purity and stability
should be used to secure good lubrication. In all cases
the oil should be sufficiently heavy to assure the highest
horse-power and fuel and oil economy compatible with
perfect lubrication, avoiding, at the same time, carbon-
ization and ignition failure. When aluminum pistons are
used their superior heat-conducting properties aid mate-
rially in reducing the rate of oil destruction.

The extraordinary evolutions described by airplanes
in flight make it a matter of vital necessity to operate
engines inclined at all angles to the vertical as well as in
an upside-down position. To meet this situation lubri-
cating systems have been elaborated so as to deliver
an abundance of oil where needed and to eliminate pos-
sible flooding of cylinders.' This is done by applying a
full force feed system, distributing oil under considerable
pressure to all working parts. Discharged through the
bearings, the oil drains down to the suction side of a
second pump located in the bottom of the base chamber.
This pump being of greater capacity than the first pre-
vents the accumulation of oil in the crank-case, and
forces it to a separate oil reservoir-cooler, whence it
flows back in rapid circulation to the pump feeding the
bearings. With this arrangement positive lubrication
is entirely independent of engine position. The lubri-
cating system of the Thomas-Morse aviation engines,
which is shown at Fig. 76, is typical of current practice.

210

Gnome Type Engines Use Castor Oil 211

GNOME TYPE ENGINES USE CASTOR OIL

The construction and operation of rotative radial
cylinder engines introduce additional difficulties of lubri-
cation to those already referred to and merit especial
attention. Owing to the peculiar alimentation systems
of Gnome type engines, atomized gasoline mixed with
air is drawn through the hollow stationary crank-shaft
directly into the crank-case which it fills on the way to
the cylinders. Therein lies the trouble. Hydrocarbon
oils are soon dissolved by the gasoline and washed off,
leaving the bearing surfaces without adequate protection
and exposed to instant wear and destruction. So castor
oil is resorted to as an indispensable but unfortunate
compromise. Of vegetable origin, it leaves a much more
bulky carbon deposit in the explosion chambers than
does mineral oil and its great affinity for oxygen causes
the formation of voluminous gummy deposit in the crank-
case. Engines employing it need to be dismounted and
thoroughly scraped out at frequent intervals. It is ad-
visable to use only unblended chemically pure castor oil
in rotative engines, first by virtue of its insolubility in
gasoline and second because its extra heavy body can
resist the high temperature of air-cooled cylinders.

HALL-SCOTT LUBRICATION SYSTEM

The oiling system of the Hall-Scott' type A-5 125
horse-power engine is clearly shown at Fig. 77. It is
completely described in the instruction book issued by
the company from which the following extracts are repro-
duced by permission. Crank-shaft, connecting rods and
all other parts within the crank-case and cylinders are
lubricated directly or indirectly by a force-feed oiling
system. The cylinder walls and wrist pins are lubricated
by oil spray thrown from the lower end of connecting
rod bearings. This system is used only upon A-5 engines.
Upon A-7a and A-5a engines a small tube supplies oil

llflil

212

Hall- Scott Lubricating System 213

from connecting rod bearing directly upon the wrist pin.
The oil is drawn from the strainer located at the lowest
portion of the lower crank-case, forced around the main
intake manifold oil jacket. From here it is circulated
to the main distributing pipe located along the lower left
hand side of upper crank-case. The oil is then forced
directly to the lower side of crank- shaft, through holes
drilled in each main bearing cup. Leakage from these
main bearings is caught in scuppers placed upon the
cheeks of the crank-shafts furnishing oil under pressure
to the connecting rod bearings. A-7a and A-5a engines
have small tubes leading from these bearings which con-
vey the oil under pressure to the wrist pins.

A bi-pass located at the front end of the distributing
oil pipe can be regulated to lessen or raise the pressure.
By screwing the valve in, the pressure will raise and
more oil will be forced to the bearings. By unscrewing,
pressure is reduced and less oil is fed. -A-7a and A-5a
engines have oil relief valves located just off of the main
oil pump in the lower crank-case. This regulates the
pressure at all times so that in cold weather there will
be no danger of bursting oil pipes due to excessive pres-
sure. If it is found the oil pressure is not maintained
at a high enough level, inspect this valve. A stronger
spring will not allow the oil to bi-pass so freely, and
consequently the pressure will be raised; a weaker spring
will bi-pass more oil and reduce the oil pressure mate-
rially. Independent of the above-mentioned system, a
small, directly driven rotary oiler feeds oil to the base
of each individual cylinder. The supply of oil is fur-
nished by the main oil pump located in the lower crank-
case. A small sight-feed regulator is furnished to control
the supply of oil from this oiler. This instrument should
be placed higher than the auxiliary oil distributor itself
to enable the oil to drain by gravity feed to the oiler.
If there is no available place with the necessary height
in the front seat of plane, connect it directly to the intake
L fitting on the oiler in an upright position. It should

214 Aviation Engines

be regulated with full open throttle to maintain an oil
level in the glass, approximately half way.

An oil pressure gauge is provided. This should be run
to the pilot's instrument board. The gauge registers the
oil pressure upon the bearings, also determining its cir-
culation. Strict watch should be maintained of this in-
strument by pilot, and if for any reason its hand should
drop to the motor should be immediately stopped and
the trouble found before restarting engine. Care should
be taken that the oil does not work up into the gauge,
as it will prevent the correct gauge registering of oil
pressure. The oil pressure will vary according to weather
conditions and viscosity of oil used. In normal weather,
with the engine properly warmed up, the pressure will
register on the oil gauge from 5 to 10 pounds when the
engine is turning from 1,275 to 1,300 r. p. m. This does
not apply to all aviation engines, however,' as the proper
pressure advised for the Curtiss 0X2 motor is from 40
to 55 pounds at the gauge.

The oil sump plug is located at the lowest point of
the lower crank-case. This is a combination dirt, water
and sediment trap. It is easily removed by unscrewing.
Oil is furnished mechanically to the cam-shaft housing
under pressure through a small tube leading from the
main distributing pipe at the propeller end of engine
directly into the end of cam-shaft housing. The opposite
end of this housing is amply relieved to allow the oil
to rapidly flow down upon cam-shaft, magneto, pinion-
shaft, and crank-shaft gears, after which it returns to
lower crank-case. An outside overflow pipe is also pro-
vided to carry away the surplus oil.

DRAINING OIL FROM: CRANK-CASE

The oil strainer is placed at the lowest point of the
lower crank-case. This strainer should be removed after
every five to eight hours running of the engine and
cleaned thoroughly with gasoline. It is also advisable
to squirt distillate up into the case through the opening

Hall-Scott Oiling System 215

where the strainer has been removed. Allow this dis-
tillate to drain out thoroughly before replacing the plug
with strainer attached. Be sure gasket is in place on
plug before replacing. Pour new oil in through either
of the two breather pipes on exhaust side of motor.
Be sure to replace strainer screens if removed. If,
through oversight, the engine does not receive sufficient
lubrication and begins to heat or pound, it should be
stopped immediately. After allowing engine to cool pour
at least three gallons of oil into oil sump. Fill radiator
with water after engine has cooled. Should there be
apparent damage, the engine should be thoroughly in-
spected immediately without further running. If no ob-
vious damage has been done, the engine should be given
a careful examination at the earliest opportunity to see
that the running without oil has not burned the bearings
or caused other trouble.

Oils best adapted for Hall-Scott engines have the fol-
lowing properties: A flash test of not less than 400 F. ;
viscosity of not less than 75 to 85 taken at 20 F. with
Saybolt's Universal Viscosimeter.

Zeroline heavy duty oil, manufactured by the Standard
Oil Company of California; also,

Gargoyle mobile B oil, manufactured by the Vacuum
Oil Company, both fulfill the above specifications. One
or the other of these oils can be obtained all over the
world.

Monogram extra heavy is also recommended.

OIL SUPPLY BY CONSTANT LEVEL SPLASH SYSTEM

The splash system of lubrication that depends on the
connecting rod to distribute the lubricant is one of the
most successful and simplest forms for simple four- and
six-cylinder vertical automobile engines, but is not as
well adapted to the oiling of airplane power plants for
reasons previously stated. If too much oil is supplied
the surplus will work past the piston rings and into the
combustion chamber, where it will burn and cause carbon

216 Aviation Engines

deposits. Too much oil will also cause an engine to smoke
and an excess of lubricating oil is usually manifested
by a bluish- white smoke issuing from the exhaust.

A good method of maintaining a constant level of oil
for the successful application of the splash system is
shown at Fig. 78. The engine base casting includes a
separate chamber which serves as an oil container and
which is below the level of oil in the crank-case. The
lubricant is drawn from the sump or oil container by
means of a positive oil pump which discharges directly
into the engine case. The level is maintained by an over-
flow pipe which allows all excess lubricant to flow back
into the oil container at the bottom of the cylinder.
Before passing into the pump again the oil is strained
or filtered by a screen of wire gauze and all foreign
matter removed. Owing to the rapid circulation of the
oil it may be used over and over again for quite a period
of time. The oil is introduced directly into the crank-
case by a breather pipe and the level is indicated by
a rod carried by a float which rises when the container is
replenished and falls when the available supply dimin-
ishes. It will be noted that with such system the only
apparatus required besides the oil tank which is cast
integral with the bottom of the crank-case is a suitable
pump to maintain circulation of oil. This member is
always positively driven, either by means of shaft and
universal coupling or direct gearing. As the system is
entirely automatic in action, it will furnish a positive
supply of oil at all desired points, and it cannot be
tampered with by the inexpert because no adjustments
are provided or needed.

DKY CRANK-CASE SYSTEM BEST FOR AIRPLANE ENGINES

In most airplane power plants it is considered desirable
to supply the oil directly to the parts needing it by suit-
able leads instead of depending solely upon the distrib-
uting action of scoops on the connecting rod big ends.
A system of this nature is shown at Fig. 77. The oil

Best Oiling System for Airplane

217

is carried in the crank-case, as is common practice, but
the normal oil level is below the point where it will be
reached by the connecting rod. It is drawn from the
crank-case by a plunger pump which directs it to a mani-
fold leading directly to conductors which supply the main

Wafer Outfetr

WaterSpac&s

WaferSpaces

Geared 0// Pts/n/?

Fig. 78. Sectional View of Typical Motor Showing Parts Needing Lubri-
cation and Method of Applying Oil by Constant Level Splash System.
Note also Water Jacket and Spaces for Water Circulation.

218

Aviation Engines

journals. After the oil has been used on these points it
drains back into the bottom of the crank-case. An excess
is provided which is supplied to the connecting rod ends
by passages drilled into the webs of the crank-shaft and
part way into the crank-pins as shown by the dotted
lines. The oil which is present at the connecting rod

Oil Strainer.
Adjusting Valve.
Oil Filler.

Reservoir.

11 Pump.

Fig. 79. Pressure Feed Oil-Supply* System of Airplane Power Plants has
Many Good Features.

crank-pins is thrown off by centrifugal force and lubri-
cates the cylinder walls and other internal parts. Kegu-
lating screws are provided so that the amount of oil
supplied the different points may be regulated at will.
A relief check valve is installed to take care of excess
lubricant and to allow any oil that does not pass back
into the pipe line to overflow or bi-pass into the main
container.

A simple system of this nature is shown graphically
in a phantom view of the crank-case at Fig. 79, in which

Why Cooling Systems Are Needed 219

the oil passages are made specially prominent. The oil
is taken from a reservoir at the bottom of the engine
base by the usual form of gear oil pump and is supplied
to a main feed manifold which extends the length of the
crank-case. Individual conductors lead to the five main
bearings, which in turn supply the crank-pins by pas-
sages drilled through the crank-shaft web. In this power
plant the connecting rods are hollow section bronze
castings and the passage through the center of the con-
necting rod serves to convey the lubricant from the
crank-pins to the wrist-pins. The cylinder walls are oiled
by the spray of lubricant thrown off the revolving crank-
shaft by centrifugal force. Oil projection by the dippers
on the connecting rod ends from constant level troughs
is unequal upon the cylinder walls of the two-cylinder
blocks of an eight- or twelve-cylinder V engine. This
gives rise, on one side of the engine, to under-lubrication,
and, on the other side, to over-lubrication, as shown at
Fig. 80, A. This applies to all modifications of splash
lubricating systems.

When a force-feed lubricating system is used, the oil,
escaping past the cheeks of both ends of the crank-pin
bearings, is thrown off at a tangent to the crank-pin
circle in all directions, supplying the cylinders on both
sides with an equal quantity of oil, as at Fig. 80, B.

WHY COOLING SYSTEMS ARE NECESSARY

The reader should understand from preceding chap-
ters that the power of an internal-combustion motor is
obtained by the rapid combustion and consequent ex-
pansion of some inflammable gas. The operation in
brief is that when air or any other gas or vapor is
heated, it will expand and that if this gas is confined
in a space which will not permit expansion, pressure will
be exerted against all sides of the containing chamber.
The more a gas is heated,- the more- pressure it will
exert upon the walls of the combustion chamber it

220

Aviation Engines

Fig. 80. Why Pressure Feed System is Best for Eight-Cylinder Vee

Airplane Engines.

Why Cooling Systems are Needed 221

confines. Pressure in a gas may be created by increasing
its temperature and inversely heat may be created by
pressure. When a gas is compressed its total volume is
reduced and the temperature is augmented.

The efficiency of any form of heat engine is deter-
mined by the power obtained from a certain fuel con-
sumption. A definite amount of energy will be liberated
in the form of heat when a pound of any fuel is burned.
The efficiency of any heat engine is proportional to the
power developed from a definite quantity of fuel with the
least loss of thermal units. If the greater proportion
of the heat units derived by burning the explosive mix-
ture could be utilized in doing useful work, the efficiency
of the gasoline engine would be greater than that of
any other form of energizing power. There is a great
loss of heat from various causes, among which can be
cited the reduction of pressure through cooling the motor
and the loss of heat through the exhaust valves when
the burned gases are expelled from the cylinder.

The loss through the water jacket of the average auto-
mobile power plant is over 50 per cent, of the total fuel
efficiency. This means that more than half of the heat
units available for power are absorbed and dissipated
by the cooling water. Another 16 per cent, is lost through
the exhaust valve, and but 33% per cent, of the heat
units do useful work. The great loss of heat through
the cooling systems cannot be avoided, as some method
must be provided to keep the temperature of the engine
within proper bounds. It is apparent that the rapid
combustion and continued series of explosions would
soon heat the metal portions of the engine to a red heat
if some means were not taken to conduct much of this
heat away. The high temperature of the parts would
burn the lubricating oil, even that of the best quality,
and the piston and rings would expand to such a degree,
especially when deprived of oil, that they would seize in
the cylinder. This would score the walls, and the friction
which ensued would tend to bind the parts so tightly

222

Aviation Engines

that the piston would stick, bearings would be burned
out, the valves would warp, and the engine would soon
become inoperative.

The best temperature to secure efficient operation is
one on which considerable difference of opinion exists
among engineers. The fact that the efficiency of an
engine is dependent upon the ratio of heat converted

Cylinder Walls
1 80 "to 550 Fahr.

,Heat of Explosion 2000 c 'to 3000 Fahr.

. Piston Heads
' 300iolOOOFahr.

.Pision Walls
; 200to400Fahr

Crank Bearing Oil /'
140 "to 250 Fahr ,*'

Sump Oil 90 to 200 Fahr/

Fig. 81. Operating Temperatures of Automobile Engine Parts Useful as a
Guide to Understand Airplane Power Plant Heat.

into useful work compared to that generated by the
explosion of the gas is an accepted fact. It is very
important that the engine should not get too hot, and
on the other hand it is equally vital that the cylinders
be not robbed of too much heat. The object of cylinder
cooling is to keep the temperature of the cylinder below
the danger point, but at the same time to have it as
high as possible to secure maximum power from the
gas burned. The usual operating temperatures of an

Cooling Systems Generally Applied 223

automobile engine are shown at Fig. 81, and this can
be taken as an approximation of the temperatures apt to
exist in an airplane engine of conventional design as well
when at ground level or not very high in the air. The
newer very high compression airplane engines in which
compressions of eight or nine atmospheres are used, or
about 125 pounds per square inch, will run considerably
hotter than the temperatures indicated.

COOLING SYSTEMS GENERALLY APPLIED

There are two general systems of engine cooling in
common use, that in which water is heated by the ab-
sorption of heat from the engine and then cooled by air,
and the other method in which the air is directed onto
the cylinder and absorbs the heat directly instead of
through the medium of water. When the liquid is em-
ployed in cooling it is circulated through jackets which
surround the cylinder casting and the water may be
kept in motion by two methods. The one generally
favored is to use a positive circulating pump of some
form which is driven by the engine to keep the water
in motion. The other system is to utilize a natural
principle that heated water is lighter than cold liquid
and that it will tend to rise to the top of the cylinder
when it becomes heated to the proper temperature and
cooled water takes its place at the bottom of the water
jacket.

Air-cooling methods may be by radiation or convec-
tion. In the former case the effective outer surface of
the cylinder is increased by the addition of flanges
machined or cast thereon, and the air is depended on
to rise from the cylinder as heated and be replaced by
cooler air. This, of course, is found only on stationary
engines. When a positive air draught is directed against
the cylinder by means of the propeller slip stream in
an airplane, cooling is by convection and radiation both.
Sometimes the air draught may be directed against the

224

Aviation Engines

cylinder walls by some form of jacket which confines it
to the heated portions of the cylinder.

COOLING BY POSITIVE WATER CIRCULATION

A typical water-cooling system in which a pump is
depended upon to promote circulation of the cooling
liquid is shown at Figs. 82 and 83. The radiator is car-
ried at the front end of the fuselage in most cases, and
serves as a combined water tank and cooler, but in some
cases it is carried at the side of the engine, as in Fig.

.Outlet Pipes for Hot Wafer

Filler

Centrifugal"
Pump

Centrifugal
Pump

Fig. 82. Water Cooling of Salmson Seven-Cylinder Radial Airplane Engine.

84, or attached to the central portion of the aerofoil or
wing structure. It is composed of an upper and lower
portion joined together by a series of pipes which may
be round and provided with a series of fins to radiate
the heat, or which may be flat in order to have the water
pass through in thin sheets and cool it more easily.
Cellular or honeycomb coolers are composed of a large
number of bent tubes which will expose a large area of
surface to the cooling influence of the air draught forced
through the radiator either by the forward movement
of the vehicle or by some type of fan. The cellular and

Cooling by Positive Circulation

225

flat tube types have almost entirely displaced the flange
tube radiators which were formerly popular because they
cool the water more effectively, and may be made lighter
than the tubular radiator could be for engines of the
same capacity.

The water is drawn from the lower header of the
radiator by the pump and is forced through -a manifold

fPU-Tracf-o/* Scre\

'Radiator, -Hot-Water P/pe. /

Filler Cafi I Hose for

Flexible Connection

Pipe from

foPvmp

Pipe from
Bottom of
Radiator to

Water Pump

r Lurrenr
ongerons
Engirt e. Bed

Fig. 83. How Water Cooling System of Thomas Airplane Engine is
Installed in Fuselage.

to the lower portion of the water jackets of the cylinder.
It becomes heated as it passes around the cylinder walls
and combustion chambers and the hot water passes out
of the top of the water jacket to the upper portion of
the radiator. Here it is divided in thin streams and
directed against comparatively cool metal which abstracts
the heat from the water. As it becomes cooler it falls
to the bottom of the radiator because its weight increases
as the temperature becomes lower. By the time it reaches

226

Aviation Engines

the lower tank of the radiator it has been cooled suffi-
ciently so. that it may be again passed around the cylin-
ders of the motor. The popular form of circulating
pump is known as the "centrifugal type" because a rotary
impeller of paddle-wheel form throws water which it
receives at a central point toward the outside and thus
causes it to maintain a definite rate of circulation. The
pump is always a separate appliance attached to the

Fig. 84. Finned Tube Radiators at the Side of Hall-Scott Airplane Power
Plant Installed in Standard Fuselage.

engine and driven by positive gearing or direct-shaft
connection. The centrifugal pump is not as positive as
the gear form, and some manufacturers prefer the latter
because of the positive pumping features. They are
very simple in form, consisting of a suitable cast body
in which a pair of spur pinions having large teeth are
carried. One of these gears is driven by suitable means,
and as it turns the other member they maintain a flow
of water around the pump body. The pump should al-
ways be installed in series with the water pipe which

Water Circulation by Natural System 227

conveys the cool liquid from the lower compartment of the
radiator to the coolest portion of the water jacket.

WATER CIRCULATION BY NATURAL SYSTEM

Some automobile engineers contend that the rapid
water circulation obtained by using a pump may cool
the cylinders too much, and that the temperature of the
engine may be reduced so much that the efficiency will
be lessened. For this reason there is a growing tendency
to use the natural method of water circulation as the
cooling liquid is supplied to the cylinder jackets just
below the boiling point, and the water issues from the
jacket at the top of the cylinder after it has absorbed
sufficient heat to raise it just about to the boiling point.

As the water becomes heated by contact with the hot
cylinder and combustion-chamber walls it rises to the top
of the water ;jacket, flows to the cooler, where enough
of the heat is absorbed to cause it to become sensibly
greater in weight. As the water becomes cooler, it falls
to the bottom of the radiator and it is again supplied
to the water jacket. The circulation is entirely automatic
and continues as long as there is a difference in tem-
perature between the liquid in the water spaces of the
engine and that in the cooler. The circulation becomes
brisker as the engine becomes hotter and thus the tem-
perature of the cylinders is kept more nearly to a fixed
point. "With the thermosyphon system the cooling liquid
is nearly always at its boiling point, whereas if the cir-
culation is maintained by a pump the engine will become
cooler at high speed and will heat up more at low speed.

With the thermosyphon, or natural system of cooling,
more water must be carried than with the pump-main-
tained circulation methods. The water spaces around
the cylinders should be larger, the inlet and discharge
water manifolds should have greater capacity, and be
free from sharp corners which might impede the flow.
The radiator must also carry more water than the form
used in connection with the pump because of the brisker

228 Aviation Engines

pump circulation which maintains the engine temperature
at a lower point. Consideration of the above will show
why the pump system is almost universally used in
connection with airplane power plant cooling.

DIRECT AIK-COOLING METHODS

The earliest known method of cooling the cylinder
of gas-engines was by means of a current of air passed
through a jacket which confined it close to the cylinder
walls and was used by Daimler on his first gas-engine.
The gasoline engine of that time was not as efficient as
the later form, and other conditions which materialized
made it desirable to cool the engine by water. Even as
gasoline engines became more and more perfected there
has always existed a prejudice against air cooling, though
many forms of engines have been used, both in automo-
bile and aircraft applications where the air-cooling method
has proven to be very practical.

The simplest system of air cooling is that in which
the cylinders are provided with a series of flanges which
increase the effective radiating surface of the cylinder
and directing an air current from a fan against the
flanges to absorb the heat. This increase in the avail-
able radiating surface of an air-cooled cylinder is neces-
sary because air does not absorb heat as readily as water
and therefore more surface must be provided that the
excess heat be absorbed sufficiently fast to prevent dis-
tortion of the cylinders. Air-cooling systems are based
on a law formulated by Newton, which is: "The rate for
cooling for a body in a uniform current of air is directly
proportional to the speed of the air current and the
amount of radiating surface exposed to the cooling
effect."

AIR-COOLED ENGINE DESIGN" CONSIDERATIONS

There are certain considerations which must be taken
into account in designing an air-cooled engine, which are
often overlooked in those forms cboled by water. Large

Air-Cooled Engines

229

valves must be provided to insure rapid expulsion of
the flaming exhaust gas and also to admit promptly the
fresh cool mixture from the carburetor. The valves of
air-cooled engines are usually placed in the cylinder-

Tracfor Screw

Air Cooled Flanged Cylinde.

Fig. 85. Anzani Testing His Five-Cylinder Air Cooled Aviation Motor
Installed in Bleriot Monoplane. Note Exposure of Flanged Cylinders
to Propeller Slip Stream.

head, in order to eliminate any pockets or sharp passages
which would impede the flow of gas or retain some of
the products of combustion and their heat. When high
power is desired multiple-cylinder engines should be used,
as there is a certain limit to the size of a successful

230 Aviation Engines

air-cooled cylinder. Much better results are secured from
those having small cubical contents because the heat from
small quantities of gas will be more quickly carried off
than from greater amounts. All successful engines of
the aviation type which have been air-cooled have been
of the multiple-cylinder type.

An air-cooled engine must be placed in .the fuselage,
as at Fig. 85, in such a 'way that there will be a positive
circulation of air around it all the time that it is in
operation. The air current may be produced by the
tractor screw at the front end of the motor, or by a
suction or blower fan attached to the crank-shaft as in the
Eenault engine or by rotating the cylinders as in the
Le Khone and Gnome motors. Greater care is required
in lubrication of the air-cooled cylinders and only the best
quality of oil should be used to insure satisfactory oiling.

The combustion chambers must be proportioned so
that distribution of metal is as uniform as possible in
order to prevent uneven expansion during increase in
temperature and uneven contraction when the cylinder
is cooled. It is essential that the inside walls of the
combustion chamber be as smooth as possible because
any sharp angle or projection may absorb sufficient heat
to remain incandescent and cause trouble by igniting the
mixture before the proper time. The best grades of cast
iron or steel should be used in the cylinder and piston
and the machine work must be done very accurately
so the piston will operate with minimum friction in the
cylinder. The cylinder bore should not exceed 4% or 5
inches and the compression pressure should never exceed
75 pounds absolute, or about five atmospheres,, or serious
overheating will result.

As an example of the care taken in disposing of the
exhaust gases in order to obtain practical air-cooling,
some cylinders are provided with a series of auxiliary
exhaust ports uncovered by the piston when it reaches
the end of its power stroke. The auxiliary exhaust ports
open just as soon as the full force of the explosion has

Air-Cooling Methods 231

been spent and a portion of the flaming gases is dis-
charged through the ports in the bottom of the cylinder.
Less of the exhaust gases remains to be discharged
through the regular exhaust member in the cylinder-head
and this will not heat the walls of the cylinder nearly
as much as the larger quantity of hot gas would. That
the auxiliary exhaust port is of considerable value is
conceded by many designers of fixed and fan-shaped air-
cooled motors for airplanes.

Among the advantages stated for direct air cooling,
the greatest is the elimination of cooling water and its
cooling auxiliaries, which is a factor of some moment,
as it permits considerable reduction in horse-power-weight
ratio of the engine, something very much to be desired.
In the temperate zone, where the majority of airplanes
are used, the weather conditions change in a very few
months from the warm summer to the extreme cold
winter, and when water-cooled systems are employed it is
necessary to add some chemical substance to the water
to prevent it from freezing. The substances commonly
employed are glycerine, wood alcohol, or a saturated
solution of calcium chloride. Alcohol has the disadvan-
tage in that it vaporizes readily and must be often re-
newed. Glycerine affects the rubber hose, while the
calcium chloride solution crystallizes and deposits salt
in the radiator and water pipes.

One of the disadvantages of an air-cooling method,
as stated by those who do not favor this system, is that
engines cooled by air cannot be operated for extended
periods under constant load or at very high speed with-
out heating up to such a point that premature ignition
of the charge may result. The water-cooling systems,
at the other hand, maintain the temperature of the engine
more nearly constant than is possible with an air-cooled
motor, and an engine cooled by water can be operated
under conditions of inferior lubrication or poor mixture
adjustment that would seriously interfere with proper
and efficient cooling by air.

232 Aviation Engines

Air-cooled motors, as a rule, use less fuel than water-
cooled engines, because the higher temperature of the
cylinder does not permit of a full charge of gas being
inspired on the intake stroke. As special care is needed
in operating an air-cooled engine to obtain satisfactory
results and because of the greater difficulty which obtains
in providing proper lubrication and fuel mixturers which
will not produce undue heating, the air-cooled system
has but few adherents at the present time, and practically
all airplanes, with but very few exceptions, are provided
with water-cooled .power plants. Those fitted with air-
cooled engines are usually short-flight types where maxi-
mum lightness is desired in order to obtain high speed
and quick climb. The water-cooled engines are best
suited for airplanes intended for long flights. The Gnome,
Le Ehone and Clerget engines are thoroughly practical
and have been widely used in France and England.
These are rotary radial cylinder types. The Anzani is
a fixed cylinder engine used on training machines, while
the Renault is a V-type engine made in eight- and twelve-
cylinder V forms that has been used on reconnaissance
and bombing airplanes with success. These types will
be fully considered in proper sequence.

CHAPTER VIII

Methods of Cylinder Construction Block Castings Influence on
Crank-Shaft Design Combustion Chamber Design Bore and
Stroke Ratio Meaning of Piston Speed Advantage of Off-Set
Cylinders Valve Location of Vital Import Valve Installation
Practice Valve Design and Construction Valve Operation
Methods of Driving Cam-Shaft Valve Springs Valve Timing
Blowing Back Lead Given Exhaust Valve Exhaust Closing,
Inlet Opening Closing the Inlet Valve Time of Ignition How
an Engine Is Timed Gnome "Monosoupape" Valve Timing
Springless Valves Four Valves per Cylinder.

THE improvements noted in the modern internal com-
bustion motors have been due to many conditions. The
continual experimenting by leading mechanical minds
could have but one ultimate result. The parts of the
engines have been lightened and strengthened, and greater
power has been obtained without increasing piston dis-
placement. A careful study has been made of the many
conditions which make for efficient motor action, and
that the main principles are well recognized by all en-
gineers is well shown by the standardization of design
noted in modern power plants. There are many different
methods of applying the same principle, and it will be
the purpose of this chapter to define the ways in which
the construction may be changed and still achieve the
same results. The various components may exist in many
different forms, and all have their advantages and dis-
advantages. That all methods are practical is best shown
by the large number of successful engines which use
radically different designs.

METHODS OF CYLINDER CONSTRUCTION

One of the most important parts of the gasoline
engine and one that has material bearing upon its effi-
ciency is the cylinder unit. The cylinders may be cast

233

234 Aviation Engines

individually, or in pairs, and it is possible to make all
cylinders a unit or block casting. Some typical methods
of cylinder construction are shown in accompanying illus-
trations. The appearance of individual cylinder castings
may be ascertained by examination of the Hall-Scott
airplane engine. Air-cooled engine cylinders are always
of the individual pattern.

Considered from a purely theoretical point of view,
the individual cylinder . casting has much in its favor.
It is advanced that more uniform cooling is possible
than where the cylinders are cast either in pairs or three
or four in one casting. More uniform cooling insures
that the expansion or change of form due to heating will
be more equal. This is an important condition because
the cylinder bore must remain true under all conditions
of operation. If the heating effect is not uniform, which
condition is liable to obtain if metal is not evenly dis-
tributed, the cylinder may become distorted by heat and
the bore be out of truth. When separate cylinders are
used it is possible to make a uniform water space and
have the cooling liquid evenly distributed around the
cylinder. In multiple cylinder castings this is not always
the rule, as in many instances, especially in four-cylinder
block motors where compactness is the main feature, there
is but little space between the cylinders for the passage
of water. Under such circumstances the cooling effect
is not even, and the stresses which obtain because of
unequal expansion may distort the cylinder to some
extent. When steel cylinders are made from forgings,
the water jackets are usually of copper or sheet steel
attached to the forging by autogenous welding; in the
case of the latter and, in some cases, the former may be
electro-deposited on the cylinders.

BLOCK CASTINGS

The advantage of casting the cylinders in blocks is
that a motor may be much shorter than it would be if
individual castings were used. It is admitted that when

Block Casting of Cylinders

235

the cylinders are cast together a more compact, rigid,
and stronger power plant is obtained than when cast
separately. There is a disadvantage, however, in that
if one cylinder becomes damaged it will be necessary to

Viewed -from Top

'ocroo/ ooo'O

Fig. 86. Views of Four-Cylinder Duesenberg Airplane Engine
Cylinder Block.

replace the entire unit, which means scrapping three
good cylinders because one of the four has failed. When
the cylinders are cast separately one need only replace
the one that has become damaged. The casting of four
cylinders in one unit is made possible by improved

236 Aviation Engines

foundry methods, and when proper provision is made for
holding the cores when the metal is poured and the
cylinder casts are good, the construction is one of dis-
tinct merit. It is sometimes the case that the proportion
of sound castings is less when cylinders are cast in
"block, but if the proper precautions are observed in
molding and the proper mixtures of cast iron used, the
ratio of defective castings is no more than when cylinders
are molded individually. As an example of the courage
of engineers in departing from old-established rules, the
cylinder casting shown at Fig. 86 may be considered
typical. This is used on the Duesenberg four-cylinder
sixteen- valve 4%" x 7" engine which has a piston dis-
placement of 496 cu. in. At a speed of 2,000 r.p.m.,
corresponding to a piston speed of 2,325 ft. per min., the
engine is guaranteed to develop 125 horse-power. The
weight of the model engine without gear reduction is
436 Ibs., but a number of refinements have been made in
the design whereby it is expected to get the weight down
to 390 Ibs. The four cylinders are cast from semi- steel
in a single block, with integral heads. The cylinder
construction is the same as that which has always
been used by Mr. Duesenberg, inlet and 'exhaust valves
being arranged horizontally opposite each other in the
head. There are large openings in the water jacket
at both sides and at the ends, which are closed by means
of aluminum covers, water-tightness being secured by
the use of gaskets. This results in a saving in weight
because the aluminum covers can be made considerably
lighter than it would be possible to cast the jacket walls,
and, besides, it permits of obtaining a more nearly uni-
form thickness of cylinder wall, as the cores can be
much better supported. The cooling water passes com-
pletely around each cylinder, and there is a very con-
siderable space between the two central cylinders, this
being made necessary in order to get the large bearing
area desirable for the central bearing.

It is common practice to cast the water jackets inte-

Advantage of Block Castings 237

gral with the cylinders, if cast iron or aluminum is used,
and this is also the most economical method of applying
it because it gives good results in practice. An important
detail is that the water spaces must be proportioned so
that they are equal around the cylinders whether these
members are cast individually, in pairs, threes or fours.
When cylinders are cast in block form it is good practice
to leave a large opening in the jacket wall which will
assist in supporting the core and make for uniform water
space. It will be noticed that the casting shown at Fig.
86 has a large opening in the side of the cylinder block.
These openings are closed after the interior of the casting
is thoroughly cleaned of all sand, core wire, etc., by brass,
cast iron or aluminum plates. These also have particular
value in that they may be removed after the motor has
been in use, thus permitting one to clean out the interior
of the water jacket and dispose of the rust, sediment,,
and incrustation which are always present after the
engine has been in active service for a time.

Among the advantages claimed for the practice of
casting cylinders in blocks may be mentioned compact-
ness, lightness, rigidity, simplicity of water piping, as well
as permitting the use of simple forms of inlet and exhaust
manifolds. The light weight is not only due- to the reduc-
tion of the cylinder mass but because the block construc-
tion permits one to lighten the entire motor. The fact
that all cylinders are cast together decreases vibration,
and as the construction is very rigid, disalignment of
working parts is practically eliminated. When inlet and
exhaust manifolds are cored in the block casting, as is
sometimes the case, but one joint is needed on each of
these instead of the multiplicity of joints which obtain
when the cylinders are individual castings. The water
piping is also simplified. In the case of a four-cylinder
block motor but two pipes are used; one for the water
to enter the cylinder jacket, the other for the cooling
liquid to discharge through.

238

Aviation Engines

INFLUENCE ON CRANK-SHAFT DESIGN

The method of casting the cylinders has a material
influence on the design of the crank-shaft as will be shown
in proper sequence. When four cylinders are combined
in one block it is possible to use a two-bearing crank-shaft.
Where cylinders are cast in pairs a three-bearing crank-
shaft is commonly supplied, and when cylinders are cast

.Copper Asbestos Gasket

"'Cylinder Li/ier

<Aluminum Cylinder
Pair Casting

.Cylinder
' Head

Fig. 87. Twin-Cylinder Block of Sturtevant Airplane Engine is Cast of
Aluminum, and Has Removable Cylinder Head.

as individual units it is thought necessary to supply a
five-bearing crank-shaft, though sometimes shafts having
but three journals are used successfully. Obviously the
shafts must be stronger and stiffer to withstand the
stresses imposed if two supporting bearings are used
than if a larger number are employed. In this connec-
tion it may be stated that there is less difficulty in secur-
ing alignment with a lesser number of bearings and there
is also less friction. On the other hand, the greater the
number of points of support a crank-shaft has the lighter
the webs can be made and still have requisite strength.

Combustion Chamber Design

239

COMBUSTION CHAMBER DESIGN

Another point of importance in the design of the cylin-
der, and one which has considerable influence upon the
power developed, is the shape of the combustion chamber.
The endeavor of designers is to obtain maximum power
from a cylinder of certain proportions, and the greater
energy obtained without increasing piston displacement
or fuel consumption the higher the efficiency of the motor.
To prevent troubles due to pre-ignition it is necessary

Fig. 88. Aluminum Cylinder Pair Casting of Thomas 150 Horse-Power
Airplane Engine is of the L Head Type.

that the combustion chamber be made so that there will
be no roughness, sharp corners, or edges of metal which
may remain incandescent when heated or which will serve
to collect carbon deposits by providing a point of anchor-
age. With the object of providing an absolutely clean
combustion chamber some makers use a separable head
unit to their twin cylinder castings, such as shown at
Fig. 87 and Fig. 88. These permit one to machine the
entire interior of the cylinder and combustion chamber.
The relation of valve location and combustion chamber
design will be considered in proper sequence. These
cylinders are cast of aluminum, instead of cast iron, as

240 Aviation Engines

is customary, and are provided with steel or cast iron
cylinder liners forced in the soft metal casting bores.

BORE AND STROKE RATIO

A question that has been a vexed one and which has
been the subject of considerable controversy is the proper
proportion of the bore to the stroke. The early gas en-
gines had a certain well-defined bore to stroke ratio, as
it was usual at that time to make the stroke twice as long
as the bore was wide, but this cannot be done when high
speed is desired. "With the development of the present-
day motor the stroke or piston travel has been gradually
shortened so that the relative proportions of bore and
stroke have become nearly equal. Of late there seems to
be a tendency among designers to return to the propor-
tions which formerly obtained, and the stroke is some-
times one and a half or one and three-quarter times the
bore.

Engines designed for high speed should have the stroke
not much longer than the diameter of the bore. The dis-
advantage of short-stroke engines is that they will not
pull well at low speeds, though they run with great regu-
larity and smoothness at high velocity. The long-stroke
engine is much superior for slow speed work, and it will
pull steadily and with increasing power at low speed.
It was formerly thought that such engines should never
turn more than a moderate number of revolutions, in
order not to exceed the safe piston speed of 1.000 feet
per minute. This old theory or rule of practice has been
discarded in designing high efficiency automobile racing
and aviation engines, and piston speeds from 2,500 to
3,000 feet per minute are sometimes used, though the
average is around 2,000 feet per minute. While both
short- and long-stroke motors have their advantages, it
would seem desirable to average between the two. That
is why a proportion of four to five or six seems to be
more general than that of four to seven or eight, which
would be a long-stroke ratio. Careful analysis of a num-

Meaning of Piston Speed 241

her of foreign aviation motors shows that the average
stroke is about 1.2 times the bore dimensions, though
some instances were noted where it was as high as 1.7
times the bore.

MEANING OF PISTON SPEED

The factor which limits the stroke and makes the
speed of rotation so dependent upon the travel of the
piston is piston speed. Lubrication is the main factor
which determines piston speed, and 'the higher the rate
of piston travel the greater care, must be taken to insure
proper oiling. Let us fully consider what is meant by
piston speed.

Assume that a motor has a piston travel or stroke of
six inches, for the sake of illustration. It would take two
strokes of the piston to cover one foot, or twelve inches,
and as there are two strokes to a revolution it will be
seen that this permits of a normal speed of 1,000 revolu-
tions per minute for an engine with a six-inch stroke, if
one does not exceed 1,000 feet per minute. If the stroke
was only four inches, a normal speed of 1,500 revolutions
per minute would be possible without exceeding the pre-
scribed limit. The crank-shaft of a small engine, having
three-inch stroke, could turn at a speed of 2,000 revolu-
tions per minute without danger of exceeding the safe
speed limit. It will be' seen that the longer the stroke
the slower the speed of the engine, if one desires to keep
the piston speed within the bounds as recommended, but
modern practice allows of greatly exceeding the speeds
formerly thought best.

ADVANTAGES OF OFF-SET CYLINDERS

Another point upon which considerable difference of
opinion exists relates to the method of placing the cylin-
der upon the crank-case i.e., whether its center line
should be placed directly over the center of the crank-
shaft, or to one side of center. The motor shown at
Fig. 90 is an off-set type, in that the center line of the

242

Aviation Engines

cylinder is a little to one side of the center of the crank-
shaft. Diagrams are presented at Fig. 91 which show
the advantages of off-set crank-shaft construction. The

Rocker Arm ----.

Exhaust

Exhaust Pipe -''

Applied Sheet""
Metal Water Jacket

Steel Cylinder-''

,'Laminctted Leaf
Spring

^, Intake Valve

,.-Coirburetor

Push and
Pull Rod

"-Cylinder
Center Line.

-Crank Shaft
Center Line

Fig. 90. Cross Section of Austro-Daimler Engine, Showing Offset Cylinder
Construction. Note Applied Water Jacket and Peculiar Valve Action.

view at A is a section through a simple motor with the
conventional cylinder placing, the center line of both
crank-shaft and cylinder coinciding. The view at B shows

Advantages of Offset Cylinders

243

the cylinder placed to one side of center so that its center
line is distinct from that of the crank-shaft and at some
distance from it. The amount of off-set allowed is a point
of contention, the usual amount being from fifteen to
twenty-five per cent, of the stroke. The advantages of
the off-set are shown at Fig. 91, C. If the crank turns

MINI

mill

\i//7e of Side
Thrust Against
Cylinder Wall,
Which Increases

With Angularity ^

of Connecting
Rod i

Resistance to /

Motion Center Line of
Crank

Note Decreased
Side Thrust
Because of Letter

Angle of
Connecting Rod

Center Line of
Cylinder

Fig. 91. Diagrams Demonstrating Advantages of Offset Crank-Shaft

Construction.

in direction of the arrow there is a certain resistance to
motion which is proportional to the amount of energy
exerted by the engine and the resistance offered by the
load. There are two thrusts acting against the cylinder
wall to be considered, that due to explosion or expansion
of the gas, and that which resists the motion of the piston.
These thrusts may be represented by arrows, one which
acts directly in a vertical direction on the piston top, the

244 Aviation Engines

other along a straight line through the center of the
connecting rod. Between these two thrusts one can draw
a line representing a resultant force which serves to bring
the piston in forcible contact with one side of the cylinder
wall, this being known as side thrust. As shown at C,
the crank-shaft is at 90 degrees, or about one-half stroke,
and the connecting rod is at 20 degrees angle. The
shorter connecting rod would increase the diagonal re-
sultant and side thrusts, while a longer one would reduce
the angle of the connecting rod and the side thrust of
the piston would be less. With the off-set construction,
as shown at D, it will be noticed that with the same con-
necting-rod length as shown at C and with the crank-
shaft at 90 degrees of the circle that the connecting-rod
angle is 14 degrees and the side thrust is reduced pro-
portionately.

Another important advantage is that greater efficiency
is obtained from the explosion with an off-set crank-shaft,
because the crank is already inclined when the piston is
at top center, and all the energy imparted to the piston
by the burning mixture can be exerted directly into pro-
ducing a useful turning effort. "When a cylinder is placed
directly on a line with the crank-shaft, as shown at A,
it will be evident that some of the force produced by the
expansion of the gas will be exerted in a direct line and
until the crank moves the crank throw and connecting
rod are practically a solid member. The pressure which
might be employed in obtaining useful turning effort is
wasted by causing a direct pressure upon the lower half
of the main bearing and the upper half of the crank-pin
bushing.

Very good and easily understood illustrations show-
ing advantages of the off-set construction are shown at
E and F. This is a bicycle crank-hanger. It is advanced
that the effort of the rider is not as well applied when
the crank is at position E as when it is at position F.
Position E corresponds to the position of the parts when
the cylinder is placed directly over the crank-shaft center.

Valve Location Practice 245

Position F may be compared to the condition which is
present when the off-set cylinder construction is used.

VALVE LOCATION OF VITAL IMPORT

It has often been said that a chain is no stronger than
its weakest link, and this is as true of the explosive motor
as it is of any other piece of mechanism. Many motors
which appeared to be excellently designed and which
were well constructed did not prove satisfactory because
some minor detail or part had not been properly consid-
ered by the designer. A factor having material bearing
upon the efficiency of the internal combustion motor is
the location of the valves and the shape of the combus-
tion chamber which is largely influenced by their placing.
The fundamental consideration of valve design is that
the gases be admitted and discharged from the cylinder
as quickly as possible in order that the speed of gas flow
will not be impeded and produce back pressure. This is
imperative in obtaining satisfactory operation in any
form of motor. If the inlet passages are constricted the
cylinder will not fill with explosive mixture promptly,
whereas if the exhaust gases are not fully expelled the
parts of the inert products of combustion retained dilute
the fresh charge, making it slow burning and causing lost
power and overheating. When an engine employs water
as a cooling medium this substance will absorb the sur-
plus heat readily, and the effects of overheating are not
noticed as quickly as when air-cooled cylinders are em-
ployed. Valve sizes have a decided bearing upon the
speed of motors and some valve locations permit the
use of larger members than do other positions.

While piston velocity is an important factor in de-
terminations of power output, it must be considered from
the aspect of the wear produced upon the various parts,
of the motor. It is evident that engines which run very
fast, especially of high power, must be under a greater
strain than those operating at lower speeds. The valve-
operating mechanism is especially susceptible to the in-

246

Aviation Engines

fluence of rapid movement, and the slower the engine the
longer the parts will wear and the more reliable the
valve action.

As will be seen by reference to the accompanying illus-
tration, Fig. 92, there are many ways in which valves may
be placed in the cylinder. Each method outlined posses-
ses some point of advantage, because all of the types

Fig. 92. Diagram Showing Forms of Cylinder Demanded by Different Valve
Placings. A T Head Type, Valves on Opposite Sides. B L Head
Cylinder, Valves Side by Side. C L Head Cylinder, One Valve in Head,
Other in Pocket. D Inlet Valve Over Exhaust Member, Both in Side
Pocket. E Valve-in-the-Head Type with Vertical Valves. F Inclined
Valves Placed to Open Directly into Combustion Chamber.

Valve Location Practice 247

illustrated are used by reputable automobile manufac-
turers. The method outlined at Fig. 92, A, is widely
used, and because of its shape the cylinder is known as
the "T" form. It is approved for automobile use for
several reasons, the most important being that large
valves can be employed and a well-balanced and symmet-
rical cylinder casting obtained. Two independent cam-
shafts are needed, one operating the inlet valves, the
other the exhaust members. The valve-operating mech-
anism can be very simple in form, consisting of a plunger
actuated by the cam which transmits the cam motion to
the valve-stem, raising the valve as the cam follower
rides on the point of the cam. Piping may be placed
without crowding, and larger manifolds can be fitted than
in some other constructions. This has special value, as
it permits the use of an adequate discharge pipe on the
exhaust side with its obvious advantages. This method
of cylinder construction is never found on airplane en-
gines because it does not permit of maximum power
output.

On the other hand, if considered from a viewpoint of
actual heat efficiency, it is theoretically the worst form of
combustion chamber. This disadvantage is probably com-
pensated for by uniformity of expansion of the cylinder
because of balanced design. The ignition spark-plug may
be located directly over the inlet valve in the path of the
incoming fresh gases, and both valves may be easily re-
moved and inspected by unscrewing the valve caps with-
out taking off the manifolds.

The valve installation shown at C is somewhat un-
usual, though it provides for the use of valves of large
diameter. Easy charging is insured because of the large
inlet valve directly in the top of the cylinder. Conditions
may be reversed if necessary, and the gases discharged
through this large valve. Both methods are used, though
it would seem that the free exhaust provided by allowing
the gases to escape directly from the combustion chamber
through the overhead valve to the exhaust manifold

248 Aviation Engines

would make for more power. The method outlined at
Fig. 92, F and at Fig. 90 is one that has been widely
employed on large automobile racing motors where ex-
treme power is required as well as in engines constructed
for aviation service. The inclination of the valves per-
mits the use of large valves, and these open directly into
the combustion chamber. There are no pockets to retain
heat or dead gas, and free intake and outlet of gas is
obtained. This form is quite satisfactory from a theo-
retical point of view because of the almost ideal combus-
tion chamber form. Some difficulty is experienced, how-
ever, in properly water-jacketing the valve chamber which
experience has shown to be necessary if the engine is to
have high power.

The motor shown at Fig. 92, B and Fig. 88 employs
cylinders of the "L" type. Both valves are placed in
a common extension from the combustion chamber, and
being located side by side both are actual from a com-
mon cam-shaft. The inlet and exhaust pipes may be
placed on the same side of the engine and a very com-
pact assemblage is obtained, though this is optional if
passages are cored in the cylinder pairs to lead the gases
to opposite sides. The valves may be easily removed
if desired, and the construction is fairly good from the
viewpoint of both foundry man and machinist. The chief
disadvantage is the limited area of the valves and the
loss of heat efficiency due to the pocket. This form of
combustion chamber, however, is more efficient than the
"T" head construction, though with the latter the use of
larger valves probably compensates for the greater heat
loss. It has been stated as an advantage of this con-
struction that both manifolds can be placed at the same
side of the engine and a compact assembly secured. On
the other hand, the disadvantage may be cited that in
order to put both pipes on the same side they must be
of smaller size than can be used when the valves are
oppositely placed. The "L" form cylinder is sometimes
made more efficient if but one valve is placed in the pocket

Valve Location Practice

249

while the other is placed over it. This construction is
well shown 'at Fig. 92, D and is found on Anzani motors.
The method of valve application shown at Fig. 87 is
an ingenious method of overcoming some of the disad-
vantages inherent with valve-in-the-head motors. In the
first place it is possible to water-jacket the valves thor-

Rocker Arm Shaft

Oil Cap "

Adjusting Ball End-
Lock Nu+

Push Pod

Valve Lifter 6 ufde
Valve. Lifter

Valve Rocker Arm
Valve Si-em

Valve Spring
"Valve Cage Nut

Valve Cage

Packing Ring

Valve' Cage
.Valve

Cylinder

. Connecting Rod

" ' Cra n k S.ha ft

Fig. 93. Sectional View of Engine Cylinder Showing Valve and Cage

Installation.

oughly, which is difficult to accomplish when they are
mounted in cages. The water circulates directly around
the walls of the valve chambers, which is superior to a
construction where separate cages are used, as there are
two thicknesses of metal with the latter, that of the valve-
cage proper and the wall of the cylinder. The cooling
medium is in contact only with the outer wall, and as
there is always a loss of heat conductivity at a joint it

250

Aviation Engines

is practically impossible to keep the exhaust valves and
their seats at a uniform temperature. The valves may
be of larger size without the use of pockets when seating
directly in the head. In fact, they could be equal in

Fig. 94. Diagrams Showing How Gas Enters Cylinder Through Overhead
Valves and Other Types. A Tee Head Cylinder. B L Head Cylinder.
C Overhead Valve.

diameter to almost half the bore of the cylinder, which
provides an ideal condition of charge placement and ex-
haust. When valve grinding is necessary the entire head
is easily removed by taking off six nuts and loosen-
ing inlet manifold connections, which operation would
be necessary even if cages were employed, as in the
engine shown at Fig. 93.

Valve Location Practice

251

At Fig. 94, A and B, a section through a typical "L"-.
shaped cylinder is depicted. It will be evident that where
a pocket construction is employed, in addition to its fac-
ulty for absorbing heat, the passage of gas would be
impeded. For example, the inlet gas rushing in through
the open valve would impinge sharply upon the valve-cap
or combustion head directly over the valve and then must
turn at a sharp angle to enter the combustion chamber

Fig. 95. Conventional Methods of Operating Internal Combustion Motor

Valves.

252

Aviation Engines

and then at another sharp angle to fill the cylinders. The
same conditions apply to the exhaust gases, though they
are reversed. When the valve-in-the-head type of cylin-
der is employed, as at C, the only resistance offered the
gas is in the manifold. As far as the passage of the
gases in and out of the cylinder is concerned, ideal condi-
tions obtain. It is claimed that valve.-in-the-head motors
are more flexible and responsive than other forms, but the
construction has the disadvantage in that the valves must
be opened through a rather complicated system of push

Tig. 96. Examples of Direct Valve Actuation "by Overhead Cam-Shaft,
A Mercedes. B Hall-Scott. C Wisconsin.

rods and rocker arms instead of the simpler and direct
plunger which can be used with either the "T" or "L"
head cylinders. .This is clearly outlined in the illustra-
tions at Fig. 95, where A shows the valve in the head-
operating mechanism necessary if the cam-shaft is car-
ried at the cylinder base, while B shows the most direct
push-rod action obtained with "T" or "L" head cylinder
placing.

The objection can be easily met by carrying the cam-
shaft above the cylinders and driving it by means of
gearing. The types of engine cylinders using this con-
struction are shown at Fig. 96, and it will be evident that
a positive and direct valve action is possible by following
the construction originated by the Mercedes (German)

Valve Location Practice 253

Fig. 97.

CENSORED

254 Aviation Engines

Fig. 98.

CENSORED

aviation engine designers and outlined at A. The other
forms at B and C are very clearly adaptations of this
design. The Hall-Scott engine at Fig. 97 is depicted in
part section and no trouble will be experienced in under-
standing the bevel pinion and gear drive from the crank-

Concentric Valve Design

255

shaft to the overhead cam-shaft through a vertical coun-
ter-shaft. A very direct valve action is used in the
Duesenberg engines, one of which is shown in part section
at Fig. 98. The valves are -parallel with the piston top
and are actuated by rocker arms, one end of which bears
against the valve stem, and the other rides the. cam-shaft.

,'Main Rocker Arm

Exhaust

Valve

Sleeve.

Auxiliary Rocker '
Arm for Inlet
Valve

Section at A-B

Inlet
Valve
Open

Fig. 99. Sectional Views Showing Arrangement of Novel Concentric Valve
Arrangement Devised by Panhard for Aerial Engines.

The form shown at Fig. 99 shows an ingenious appli-
cation of the valve-in-the-head idea which permits one
to obtain large valves. It has been used on some of the
Panhard aviation engines and on the American Aero-
marine power plants. The inlet passage is controlled
by the sliding sleeve which is hollow and slotted so as
to permit the inlet gases to enter the cylinder through
the regular type poppet valve which seats in the exhaust
sleeve. When the exhaust valve is operated by the tap-
pet rod and rocker arm the intake valve is also carried

256 Aviation Engines

down with it. The intake gas passage is closed, however,
and the burned gases are discharged through the large
annular passage surrounding the sleeve. When the inlet
valve leaves its seat in the sleeve the passage of cool
gas around the sleeve keeps the temperature of both
valves to a low point and the danger of warping is mini-
mized. A dome-shaped combustion chamber may be used,
which is an ideal form in conserving heat efficiency, and
as large values may be installed the flow of both fresh
and exhaust gases may be obtained with minimum resist-
ance. The intake valve is opened by a small auxiliary
rocker arm which is lifted when, the cam follower rides
into the depression in the cam by the action of the strong
spring around the push rod. .When the cam follower rides
on the high point the exhaust sleeve is depressed from
its seat against the cylinder. By using a cam having both
positive and negative profiles, a single rod suffices for
both valves because of its push and pull action.

VALVE DESIGN AND CONStRTJCTION

Valve dimensions are an important detail to be con-
sidered and can be determined by several conditions,
among which may be cited method of installation, oper-
ating mechanism, material employed, engine speed de-
sired, manner of cylinder cooling and degree of lift
desired. A review of various methods of valve location
has shown that when the valves are placed directly in
the head we can obtain the ideal cylinder form, though
larger valves may be used if housed in a separate pocket,
as afforded by the "T" head construction. The method
of operation has much to do with the size of the valves.
For example, if an automatic inlet valve is employed it
is good practice to limit the lift and obtain the required
area of port opening by augmenting the diameter. Be-
cause of this a valve of the automatic type is usually
made twenty per cent, larger than one mechanically oper-
ated. When both are actuated by cam mechanism, as is
now common practice, they are usually made the same

Valve Design and Construction 257

size and are interchangeable, which greatly simplifies
manufacture. The relation of valve diameter to cylin-
der bore is one that has been discussed for some time
by engineers. The writer's experience would indicate that
they should be at least half the bore, if possible. While
the mushroom type or poppet valve has become standard
and is the most widely used form at the present time,
there is some difference of opinion among designers as
to the materials employed and the angle of the seat. Most
valves have a bevel seat, though some have a flat seating.
The flat seat valve has the distinctive advantage of pro-
viding a clear opening with lesser lift, this conducing to
free gas flow. It also has value because it is silent in
operation, but the disadvantage is present that best mate-
rial and workmanship must be used in their construction
to obtain satisfactory results. As it can be made very
light it is particularly well adapted for use as an auto-
matic inlet valve. Among other disadvantages cited is
the claim that it is more susceptible to derangement, owing
to the particles of foreign matter getting under the seat.
With a bevel seat it is argued that the foreign matter
would be more easily dislodged by the gas flow, and that
the valve would close tighter because it is drawn posi-
tively against the bevel seat.

Several methods of valve construction are the vogue,
the most popular form being the one-piece type; those
which are composed of a head of one material and stem
of another are seldom used in airplane engines because
they are not reliable. In the built-up construction the
head is usually of high nickel steel or cast iron, which
metals possess good heat-resisting qualities. Heads made
of these materials are not likely to warp, scale, or pit,
as is sometimes the case when ordinary grades of ma-
chinery steel are used. The cast-iron head construction
is not popular because it is often difficult to keep the head
tight on the stem. There is a slight difference in ex-
pansion ratio between the head and the stem, and as the
stem is either screwed or riveted to the cast-iron head

258

Aviation Engines

the constant hammering of the valve against its seat may
loosen the joint. As soon as the head is loose on the stem
the action of the valve becomes erratic. The best practice
is to machine the valves from tungsten steel forgings.
This material has splendid heat-resisting qualities and
will not pit or become scored easily. Even the electri-
cally welded head to stem types which are used in auto-

L/ne rearrr

a -f ter assembling

. 375*. 0005 --

Fig. 100. Showing Clearance Allowed Between Valve Stem
and Valve Stem Guide to Secure Free Action.

mobile engines are not looked upon with favor in the
aviation engine. Valve stem guides and valve stems must
be machined very accurately to insure correct action. The
usual practice in automobile engines is shown at Fig. 100.

VALVE OPERATION"

The methods of valve operation commonly used vary
according to the type of cylinder construction employed.
In all cases the valves are lifted from their seats by cam-
actuated mechanism. Various forms of valve-lifting cams
are shown at Fig. 101. As will be seen, a cam consists

Valve-Lifting Cams

259

of a circle to which, a raised, approximately triangular
member has been added at one point. When the cam
follower rides on the circle, as shown at Fig. 1.02, there
is no difference in height between the cam center and its
periphery and there is no movement of the plunger. As
soon as the raised portion of the cam strikes the plunger
it will lift it, and this reciprocating movement is trans-
mitted to the valve stem by suitable mechanical connec-
tions.

The cam forms outlined at Fig. 101 are those com-
monly used. That at A is used on engines where it is

Fig. 101. Forms of Valve-Lifting Cams Generally Employed. A Cam
Profile for Long Dwell and Quick Lift. B Typical Inlet Cam Used
with Mushroom Type Follower. C Average Form of Cam. D
Designed to Give Quick Lift and Gradual Closing.

desired to obtain a quick lift arid to keep the valve fully
opened as long as possible. It is a noisy form, however,
and is not very widely employed. That at B is utilized
more often as an inlet cam while the profile shown at C
is generally depended on to operate exhaust valves. The
cam shown at D is a? composite form which has some
of the features of the other three types. It will give the
quick opening of form A, the gradual closing of form B,
and the time of maximum valve opening provided by cam
profile C.

The various types of valve plungers used are shown
at Fig. 102. That shown at A is the simplest form, con-
sisting of a simple cylindrical member having a rounded
end which follows the cam profile. These are sometimes

260

Aviation Engines

made of square stock or kept from rotating by means of
a key or pin. A line contact is possible when the plunger
is kept from turning, whereas but a single point bearing
is obtained when the plunger is cylindrical and free to
revolve. The plunger shown at A will follow only cam
profiles which have gradual lifts. The plunger shown at
B is left free to revolve in the guide bushing and is pro-

Fig. 102. Showing Principal Types of Cam Followers which Have Received

General Application.

vided with a flat mushroom head which serves as a cam
follower. The type shown at C carries a roller at its
lower end and may follow very irregular cam profiles if
abrupt lifts are desired. While forms A and B are the
simplest, that outlined at C in its various forms is more
widely used. Compound plungers are used on the Curtiss
0X2 motors, one inside the other. The small or inner one
works on a cam of conventional design, the outer plunger
follows a profile having a flat spot to permit of a pull
rod action instead of a push rod action. All the methods
in which levers are used to operate valves are more or
less noisy because clearance must be left between the valve
stem and the stop of the plunger. The space must be
taken up before the valve will leave its seat, and when

Valve-Stem Clearances

261

the engine is operated at high speeds the forcible contact
between the plunger and valve stem produces a rattling
sound until the valves become heated and expand and the
stems lengthen out. Clearance must be left between the
valve stems and actuating means. This clearance is clearly
shown in Fig. 103 and should be .020" (twenty thou-
sandths) when engine is cold. The amount of clearance
allowed depends entirely upon the design of the engine

Screw

Cam Follower

f ' Rocker
-?' Levers

Lock
Screw

Valve,-
Si-em

Fig. 103. Diagram Showing Proper Clearance to Allow Between Adjust-
ing Screw and Valve Stems in Hall-Scott Aviation Engines.

and length of valve stem. On the Curtiss 0X2 engines
the clearance is but .010" (ten thousandths) because the
valve stems are shorter. Too little clearance will result
in loss of power or misfiring when engine is hot. Too
much clearance will not allow the valve to open irs full
amount and will disturb the timing.

METHODS OF DRIVING CAM-SHAFT

Two systems of cam-shaft operation are used. The
most common of these is by means of gearing of some
form. If the cam-shaft is at right angles to the crank-
shaft it may be driven by worm, spiral, or bevel gearing.

262 Aviation Engines

If the cam-shaft is parallel to the crank-shaft, simple spur
gear or chain connection may be used to turn it. A typi-
cal cam-shaft for an eight-cylinder V engine is shown at
Fig. 104. It will be seen that the sixteen cams are forged
integrally with the shaft and that it is spur-gear driven.
The cam-shaft drive of the Hall-Scott motor is shown at
Fig. 97.

While gearing is more commonly used, considerable
attention has -been directed of late to silent chains for
cam-shaft operation. The ordinary forms of block or
roller chain have not proven successful in this applica-

Resr Bearing-^

ter Bearing

Pig. 104. Cam-Shaft of Thomas Airplane Motor Has Cams Forged Integ-
ral. Note Split Cam-Shaft Bearings and Method of Gear Retention. .

tion, but the silent chain, which is in reality a link belt
operating over toothed pulleys, has demonstrated its
worth. The tendency to its use is more noted on foreign
motors than those of American design. It first came to
public notice when employed on the Daimler-Knight en-
gine for driving the small auxiliary crank-shafts w r hich
reciprocated the sleeve valves. The advantages cited for
the application of chains are, first, silent operation, which
obtains even after the chains have worn considerably;
second,. in designing it is not necessary to figure on main-
taining certain absolute center distances between the
crank- shaft and cam-shaft sprockets, as would be the case
if conventional forms of gearing were used. On some
forms of motor employing gears, three and even four

Valve Springs 263

members are needed to turn the cam-shaft. With a chain
drive but two sprockets are necessary, the chain forming
a flexible connection which permits the driving and driven
members to be placed at any distance apart that the
exigencies of the design demand. When chains are used
it is advised that some means for compensating chain
slack be provided, or the valve timing will lag when
chains are worn. Many combination drives may be
worked out with chains that would not be possible with
other forms of gearing. Direct gear drive is favored at
the present time by airplane engine designers because they
are the most certain and positive means, even when a
number of gears must be used as intermediate drive
members. With overhead cam-shafts, bevel gears work
out very well in practice, as in the Hall-Scott motors and
others of that type.

VALVE SPRINGS

Another consideration of importance is the use of
proper valve-springs, and particular care should be taken
with those of automatic valves. The spring must be weak
enough to allow the valve to open when the suction is
light, and must be of sufficient strength to close it in
time at high speeds. It should be made as large as pos-
sible in diameter and with a large number of convolutions,
in order that fatigue of the metal be obviated, and it is
imperative that all springs be of the same strength when
used on a multiple-cylinder engine. Practically all valves
used to control the gas flow in airplane engines are me-
chanically operated. On the exhaust valve the spring
must be strong enough so that the valve will not be sucked
in on the inlet stroke. It should be borne in mind that
if the spring is too strong a strain will be imposed on
the valve-operating mechanism, and a hammering action
produced which may cause deformation of the valve- seat.
Only pressure enough to insure that the operating mech-
anism will follow the cam is required. It is common
practice to make the inlet and exhaust valve springs of

264

Aviation Engines

the same tension when the valves are of the same size
and both mechanically operated. This is done merely to
simplify manufacture and not because it is necessary for

Sparh Plug

Cranks

Derating
Sleeves

Outer Sleeve

ner Sleeve

Fig. 105. Section Through Cylinder of Knight Motor, Showing Important
Parts of Valve Motion.

the inlet valve-spring to be as strong as the other. Valve
springs of the helical coil type are generally used, though
torsion or "scissors" springs and laminated or single-
leaf springs are also utilized in special applications. Two

Valve Springs

265

springs are used on each valve in some valve-in-the-head
types; a spring of small pitch diameter inside the regular
valve-spring and concentric with it. Its function is to

.Exhaust

Intake

Spark Plug

..-Water
Space

Piston-

Intake Stroke-Intake Ports Open

Compression Stroke -All Ports Closed

Firing Stroke -All Ports Closed

Exhaust Stroke -Exhaust Ports Open

Fig. 106. Diagrams Showing Knight Sleeve Valve Action.

keep the valve from falling into the cylinder in event of
breakage of the main spring in some cases, and to provide
a stronger return action in others.

266 ,> Aviation Engines

KNIGHT SLIDE VALVE MOTOR

The sectional view through the cylinder at Fig. 105
shows the Knight sliding sleeves and their actuating
means very clearly. The diagrams at Fig. 106 show
graphically the sleeve movements and their relation to
the crank-shaft and piston travel. The action may be
summed up as follows: The inlet port begins to open
when the lower edge of .the opening of the outside sleeve
which is moving down passes the top of the slot in the
inner member also moving downwardly. The inlet port
is closed when the. lower edge of the slot in the inner
sleeve which is moving up passes the top edge of the port
in the outer sleeve which is also moving toward the top
of the cylinder. The inlet opening extends over two hun-
dred degrees of crank motion. The exhaust port is un-
covered slightly when the lower edge of the port in the
inner sleeve which is moving down passes the lower edge
of the portion of the cylinder head which protrudes in
the cylinder. When the top of the port in the outer sleeve
traveling toward the bottom of the cylinder passes the
lower edge of the slot in the cylinder wall the exhaust
passage is closed. The exhaust opening extends over a
period corresponding to about two hundred and forty
degrees of crank motion. The Knight motor has not been
applied to aircraft to the writer's knowledge, but an
eight-cylinder Vee design that might be useful in that
connection if lightened is shown at Fig. 107. The main
object is to show that the Knight valve action is the only
other besides the mushroom or poppet valve that has been
applied successfully to high speed gasoline engines.

VALVE TIMING

It is in valve timing that the greatest difference of
opinion prevails among engineers, and it is rare that one
will see the same formula in different motors. It is true
that the same timing could not be used with motors of

Valve-Timing Practice

267

different construction, as there are many factors which
determine the amount of lead to be given to the valves.
The most important of these is the relative size of the
valve to the cylinder bore, the speed of rotation it is

Priming Cups - N

Cylinder Oi

tt.T.Coil*

Wiring Header^ \
Junk Ring, \ \

Cylinder \
Head, '

, \ Hot A ir Conn
toCarburetor

Piston-"'

Ex. Pipe, s /'

Cylinder-^ "" / ,

Outer Sleeve
Inner Sleeve-'
Conn. Rod-'
Oil.By-pass Pody Valve'j'
Mam Bearing' Oil Lead

\~Long Ecc. Shaft Rod
'Short Ecc.Shaft 'Rod
Eccentric Shafts

**"- Crank-Shaft with
Counter-weight

Drain Plug-""

i.C.tUtSTROM M.y.

Fig. 107. Cross Sectional View of Knight Type Eight Cylinder V Engine.

desired to obtain, the fuel efficiency, the location of the
valves, and other factors too numerous to mention.

Most of the readers should be familiar with the cycle
of operation of the internal combustion motor of the
four-stroke type, and it seems unnecessary to go into
detail except to present a review. The first stroke of the
piston is one in which a charge of gas is taken into the

268 Aviation Engines

motor; the second stroke, which is in reverse direction
to the first, is a compression stroke, at the end of which
the spark takes place, exploding the charge and driving
the piston down on the third or expansion stroke, which
is in the same direction as the intake stroke, and finally,
after the piston has nearly reached the end of this stroke,
another valve opens to allow the burned gases to escape,
and remains open until the piston has reached the end
of the fourth stroke and is in a position to begin the
series over again. The ends of the strokes are reached
when the piston comes to a stop at either top or bottom
of the cylinder and reverses its motion. That point is
known as a center, and there are two for each cylinder,
top and bottom centers, -respectively.

All circles may be divided into 360 parts, each of
which is known as a degree, and, in tnrn, each of these
degrees may be again divided into minutes and seconds,
though we need not concern ourselves with anything less
than the degree. Each stroke of the piston represents
180 degrees travel of the crank, because two strokes rep-
resent one complete revolution of three hundred and sixty
degrees. The top and bottom centers are therefore sep-
arated by 180 degrees. Theoretically each phase of a
four-cycle engine begins and ends at a center, though in
actual practice the inertia or movement of the gases
makes it necessary to allow a lead or lag to the valve, as
the case may be. If a valve opens before a center, the
distance is called "lead"; if it closes after a center, this
distance is known as "lag." The profile of the cams
ordinarily used to open or close the valves represents a
considerable time in relation to the 180 degrees of the
crank-shaft travel, and the area of the passages through
which the gases are admitted or exhausted is quite small
owing to the necessity of having to open or close the
valves at stated times; therefore, to open an adequately
large passage for the gases it is necessary to open the
valves earlier and close them later than at centers.
That advancing the opening of the exhaust valve was

Valve-Timing Practice 269

of value was discovered on the early motors and is ex-
plained by the necessity of releasing a large amount of
gas, the volume of which has been greatly raised by the
heat of combustion. When the inlet valves were mechan-
ically operated it was found that allowing them to lag
at closing enabled the inspiration of a greater volume of
gas. Disregarding the inertia or flow of the gases, open-
ing the exhaust at center would enable one to obtain full
value of the expanding gases the entire length of the
piston stroke, and it would not be necessary to keep the
valve open after the top center, as the reverse stroke
would produce a suction effect which might draw some
of the inert charge back into the cylinder. On the other
hand, giving full consideration to the inertia of the gas,
opening the valve before center is reached will provide
for quick expulsion of the gases, which have sufficient
velocity at the end of the stroke, so that if the valve is
allowed to remain open a little longer, the amount of lag
varying with the opinions of the designer, the cylinder
is cleared in a more thorough manner.

BLOWING BACK

When the factor of retarded opening is considered
without reckoning the inertia of the gases, -it would
appear that if the valve were allowed to remain open
after center had passed, say, on the closing of the inlet,
the piston, having reversed its motion, would have the
effect of expelling part of the fresh charge through the
still open valve as it passed inward at its compression
stroke. This effect is called blowing back, and is often
noted with motors where the valve settings are not ab-
solutely correct, or where the valve-springs or seats are
defective and prevent proper closing.

This factor is not of as much import as might appear,
as on closer consideration it will be seen that the move-
ment of the piston as the crank reaches either end of the
stroke is less per degree of angular movement than it
is when the angle of the connecting rod is greater. Then,

270 Aviation Engines

again, a certain length of time is required for the reversal
of motion of the piston, during which time the crank is
in motion but the piston practically at a standstill. If the
valves are allowed to remain open during this period,
the passage of the gas in or out of the cylinder will be
by its own momentum.

LEAD GIVEN EXHAUST VALVE

The faster a motor turns, all other things being equal,
the greater the amount of lead or advance it is necessary
to give the opening of the exhaust valve. It is self-evi-
dent truth that if the speed of a motor is doubled it
travels twice as many degrees in the time necessary to
lower the pressure. As most designers are cognizant of
this fact, the valves are proportioned accordingly. It is
well to consider in this respect that the cam profile has
much to do with the manner in w T hich the valve is opened ;
that is, the lift may be abrupt and the gas allowed to
escape in a body, or the opening may be gradual, the
gas issuing from the cylinder in thin streams. An analogy
may be made with the opening of any bottle which con-
tains liquid highly carbonated. If the cork is removed
suddenly the gas escapes with a loud pop, but, on the
other hand, if the bottle is uncorked gradually, the gas
escapes from the receptacle in thin streams around the
cork, and passage of the gases to the air is accomplished
without noise. While the second plan is not harsh, it
is slower than the former, as must be evident.

EXHAUST CLOSING, INLET OPENING

A point which has been much discussed by engineers
is the proper relation of the closing of the exhaust valve
and the opening of the inlet. Theoretically they should
succeed each other, the exhaust closing at upper dead
center and the inlet opening immediately afterward. The
reason why a certain amount of lag is given the exhaust
closing in practice is that the piston cannot drive the

Valve-Timing Practice 271

gases out of the cylinder unless they are compressed to
a degree in excess of that existing in the manifold or
passages, and while toward the end of the stroke this
pressure may be feeble, it is nevertheless indispensable.
At the end of the piston's stroke, as marked by the upper
dead center, this compression still exists, no matter how
little it may be, so that if the exhaust valve is closed and
the inlet opened immediately afterward, the pressure
which exists in the cylinder may retard the entrance of
the fresh gas and a certain portion of the inert gas may
penetrate into the manifold. As the piston immediately
begins to aspirate, this may not be serious, but as these
gases are drawn back into the cylinder the fresh charge
will be diluted and weakened in value. If the spark-pltig
is in a pocket, the points may be surrounded by this weak
gas, and the explosion will not be nearly as energetic as
when the ignition spark takes place in pure mixture.

It is a well-known fact that the exhaust valve should
close after dead center and that a certain amount of lag
should be given to opening, of the inlet. The lag given
the closing of the exhaust valve should not be as great
as that given the closing of the inlet valve. Assuming
that the excess pressure of the exhaust will equal the
depression during aspiration, the time necessary to com-
plete the emptying of the cylinder will be proportional
to the volume of the gas within it. At the end of the
suction stroke the volume of gas contained in the cylinder
is equal to the cylindrical volume plus the space of the
combustion chamber. At the end of the exhaust stroke
the volume is but that of the dead space, and from one-
third to one-fifth its volume before compression. While
it is natural to assume that this excess of burned gas
will escape faster than the fresh gas will enter the cylin-
der, it will be seen that if the inlet valve were allowed
to lag twenty degrees, the exhaust valve lag need not be
more than five degrees, providing that the capacity of
the combustion chamber was such that the gases occupied
one-quarter of their former volume.

272 Aviation Engines

It is evident that no absolute rule can be given, as
back pressure will vary with the design of the valve
passages, the manifolds, and the construction of the
muffler. The more direct the opening, the sooner the
valve can be closed and the better the cylinder cleared.
Ten degrees represent an appreciable angle of the crank,
and the time required for the crank to cover this angular
motion is not inconsiderable and an important quantity of
the exhaust may escape, but the piston is very close to
the dead center after the distance has been covered.

Before the inlet valve opens there should be a certain
depression in the cylinder, and considerable lag may be
allowed before the depression is appreciable. So far as
the volume of fresh gas introduced during the admission
stroke is concerned, this is determined by the displace-
ment of the piston between the point where the inlet valve
opens and the point of closing, assuming that sufficient
gas has been inspired so that an equilibrium of pressure
has been established between the interior of the cylinder
and the outer air. The point of inlet opening varies with
different motors. It would appear that a fair amount of
lag would be fifteen degrees past top center for the inlet
opening, as a certain depression will exist in the cylinder,
assuming that the exhaust valve has closed five or ten
degrees after center, and at the same time the piston has
not gone down far enough on its stroke to materially
decrease the amount of gas which will be taken into the
cylinder.

CLOSING THE INLET VALVE

As in the case with the other points of opening and
closing, there is a wide diversity of practice as relates
to closing the inlet valve. Some of the designers close
this exactly at bottom center, but this practice cannot
be commended, as there is a considerable portion of time,
at least ten or fifteen degrees angular motion of the crank,
before the piston will commence to travel to any extent
on its compression stroke. The gases rushing into the

Valve-Timing Practice 27 B

cylinder have considerable velocity, and unless an equi-
librium is obtained between the pressure inside and that
of the atmosphere outside, they will continue to rush into
the cylinder even after the Diston ceases to exert any
suction effect.

For this reason, if the valve is closed exactly on cen-
ter, a full charge may not be inspired into the cylinder,
though if the time of- closing is delayed, this momentum
or inertia of the gas will be enough to insure that a
maximum charge is taken into the cylinder. The writer
considers that nothing will be gained if the valve is al-
lowed to remain open longer than twenty degrees, and an
analysis of practice in this respect would seem to confirm
this opinion. From that point in the crank movement
the piston travel increases and the compressive effect is
appreciable, and it would appear that a considerable pro-
portion of the charge might be exhausted into the mani-
fold and carburetor if the valve were allowed to remain
open beyond a point corresponding to twenty degrees
angular movement of the crank.

TIME OF IGNITION

In this country engineers unite in providing a vari-
able time of ignition, though abroad some difference of
opinion is noted on this point. The practice of advanc-
ing the time of ignition, when affected electrically, was
severely condemned by early makers, these maintaining
that it was necessary because of insufficient heat and
volume of the spark, and it was thought that advancing
ignition was injurious. The engineers of to-day appre-
ciate the fact that the heat of the electric spark, espe-
cially when from a mechanical generator of electrical
energy, is the only means by which we can obtain prac-
tically instantaneous explosion, as required by the opera-
tion of motors at high speeds, and for the combustion
of large volumes of gas.

It is apparent that a motor with a fixed point of

274

Aviation Engines

ignition is not as desirable, in every way, as one in which
the ignition can be advanced to best meet different re-
quirements, and the writer does not readily perceive any

*5 Position of No. I Cylinder Cams

when No. I Piston is on top dead center

Part

Diagram of Gears in Hall-Scott-
Type A-5 Aviation Motor

'Exhaust Closed

Part- B

Magneto \

fully

Advanced

<sv^ ,'ExhaustC.

Vx*""" L7~jk\ ""V. ^

Intake Closed'

'Exhaust-
Open

Section thru Cam Shaft

Housing Showing position of

Cams.when Exhaust Valve is Closed

Note on Chart that Crank-Shaft
is 10 past top center when
Exhaust Valve. is closed

Fig. 108. Diagrams Explaining Valve and Ignition Timing of Hall-Scott

Aviation Engine.

advantage outside of simplicity of control in establishing
a fixed point of ignition. In fact, there seems to be some
difference of opinion among those designers who favor

Ignition Timing

275

fixed ignition, and in one case this is located forty-three
degrees ahead of center, and in another motor the point
is fixed at twenty degrees, so that it may be said that
this will vary as much as one hundred per cent, in various
forms. This point will vary with different methods of

Dead Center
1*6

Fig. 109. Timing Diagram of Typical Six-Cylinder Engine.

ignition, as well as the location of the spark-plug or
igniter. For the sake of simplicity, most airplane en-
gines use set spark; if an advancing and retarding mech-
anism is fitted, it is only to facilitate starting, as the
spark is kept advanced while in flight, and control is by
throttle alone.

It is obvious by consideration of the foregoing that
there can be no arbitrary rules established for timing,

276

Aviation Engines

because of the many conditions which determine the best
times for opening and closing the valves. It is customary
to try various settings when a new motor is designed
until the most satisfactory points are determined, and
the setting which will be very suitable for one motor is
not always right for one of different design. The timing

Fig. 110. Timing Diagram of Typical Eight-Cylinder V Engine.

diagram shown at Fig. 108 applies to the Hall- Scott
engine, and may be considered typical. It should be
easily followed in view of the very complete explanation
given in preceding pages. Another six-cylinder engine
diagram is shown at Fig. 109, and an eight-cylinder tim-
ing diagram is shown at Fig. 110. In timing automobile
engines no trouble is experienced, because timing marks

How an Engine is Timed 277

are always indicated on the engine fly-wheel register with
an indicating trammel on the ^crank-case. To time an
airplane engine accurately, as is necessary to test for a
suspected cam-shaft defect, a timing disc of aluminum is
attached to the crank-shaft which has the timing marks
indicated thereon. If the disc is made 10 or 12 inches
in diameter, it may be divided into degrees without
difficulty.

HOW AN ENGINE IS TIMED

In timing a motor from the marks on the timing disc
rim it is necessary to regulate the valves of but one
cylinder at a time. Assuming that the disc is revolving
in the direction of engine rotation, and that the firing
order of the cylinders is 1-3-4-2, the operation of timing
would be carried on as follows: The crank-shaft would
be revolved until the line marked "Exhaust opens 1 and
4" registered with the trammel on the motor bed. At this
point the exhaust-valve of either cylinder No. 1 or No. 4
should begin to open. This can be easily determined by
noting which of these cylinders holds the compressed
charge ready for ignition. Assuming that the spark has
occurred in cylinder No. 1, then when the fly-wheel is
turned from the position to that in which the line marked
"Exhaust opens 1 and 4" coincides with the trammel
point, the valve-plunger under the exhaust-valve of cylin-
der No. 1 should be adjusted in such a way that there is
no clearance between it and the valve stem. Further
movement of the wheel in the same direction should pro-
duce a lift of the exhaust valve. The disc is turned about
two hundred and twenty-five degrees, or a little less than
three-quarters of a revolution; then the line marked
"Exhaust closes 1 and 4" will register with the trammel
point. At this period the valve-plunger and the valve-
stem should separate and a certain amount of clearance
obtain between them. The next cylinder to time would
be No. 3. The crank-shaft is rotated until mark "Exhaust
opens 2 and 3" comes in line with the trammel. At this

278 Aviation Engines

point the exhaust valve of cylinder No. 3 should be just
about opening. The closing is determined by rotating the
shaft until the line " Exhaust closes 2 and 3" comes
under the trammel.

This operation is carried on with all the cylinders,
it being well to remember -that but one cylinder is work-
ing at a time and that a half -revolution of the fly-wheel
corresponds to a full working stroke of all the cylinders,
and that while one is exhausting the others are respec-
tively taking in a new charge, compressing and exploding.
For instance, if cylinder No. 1 has just completed its
power-stroke, the piston in cylinder No. 3 has reached
the point where the gas may be ignited to advantage.
The piston of cylinder No. 4, which is next to fire, is at
the bottom of its stroke and will have inspired a charge,
while cylinder No. 2, which is the last to fire, will have
just finished expelling a charge of burned gas, and will
be starting the intake stroke. This timing relates to a
four-cylinder engine in order to simplify the explanation.
The timing instructions given apply only to the conven-
tional motor types. Eotary cylinder engines, especially
the Gnome "monosoupape," have a distinctive valve
timing on account of the peculiarities of design.

GNOME "MONOSOUPAPE" VALVE TIMING

In the present design of the Gnome motor, a cycle of
operations somewhat different from that employed in the
ordinary four-cycle engine is made use of, says a writer
in "The Automobile," in describing the action of this
power-plant. This cycle does away with the need for the
usual inlet valve and makes the engine operable with only
a single valve, hence the name mono soup ape, or " single-
valve. " The cycle is as follows: A charge being com-
pressed in the outer end of the cylinder or combustion
chamber, it is ignited by a spark produced by the spark-
plug located in the side of this chamber, and the burning
charge expands as the piston* moves down in the cylinder
while the latter revolves around the crank-shaft. When

Gnome Monosoupape Timing 279

the piston is about half-way down on the power stroke,
the exhaust valve, which is located in the center of the
cylinder-head, is mechanically opened, and during the
following upstroke of the piston the burnt gases are
expelled from the cylinder through the exhaust valve
directly into the atmosphere.

Instead of closing at the end of the exhaust stroke,
or a few degrees thereafter, the exhaust valve is held
open for about two-thirds of the following inlet stroke
of the piston, with the result that fresh air is drawn
through the exhaust valve into the cylinder. "When the
cylinder is still 65 degrees from the end of the inlet half-
revolution, the exhaust valve closes. As no more air
can get into the cylinder, and as the piston continues to
move inwardly, it is obvious that a partial vacuum is
formed.

When the cylinder approaches within 20 degrees of
the end of the inlet half -re volution a series of small
inlet ports all around the circumference of the cylinder
wall is uncovered by the top edge of the piston, whereby
the combustion chamber is placed in communication with
the crank chamber. As the pressure in the crank chamber
is substantially atmospheric and that in the combustion
chamber is below atmospheric, there results a suction
effect which causes the air from the crank chamber to
flow into the combustion chamber. The air in the crank
chamber is heavily charged with gasoline vapor, which
is due to the fact that a spray nozzle connected with the
gasoline supply tank is located inside the chamber. The
proportion of gasoline vapor in the air in the crank
chamber is several times as great as in the ordinary
combustible mixture drawn from a carburetor into the
cylinder. This extra-rich mixture is diluted in the com-
bustion chamber with the air which entered it through
the exhaust valve during the first part of the inlet stroke,
thus forming a mixture of the proper proportion for
complete combustion.

The inlet ports in the cylinder wall remain open until

280 Aviation Engines

20 degrees of the compression half-revolution has been
completed, and from that moment to near the end of the
compression stroke . the gases are compressed in the
cylinder. Near the end of the stroke ignition takes place
and this completes the cycle.

The exact timing of the different phases of the cycle
is shown in the diagram at Fig. 111. It will be seen that
ignition occurs substantially 20 degrees ahead of the
outer dead center, and expansion of the burning gases
continues until 85 degrees past the outer dead center,
when the piston is a little past half-stroke. Then the
exhaust-valve opens and remains open for somewhat
more than a complete revolution of the cylinders, or, to
be exact, for 390 degrees of cylinder travel, until 115
degrees past the top dead center on the second revolution.
Then for 45 degrees of travel the charge within the
cylinder is expanded, whereupon the inlet ports are un-
covered and remain open for 40 degrees of cylinder
travel, 20 degrees on each side of the inward dead center
position.

SPRINGLESS VALVES

Springless valves are the latest development on French
racing car engines, and it is possible that the positively-
operated types will be introduced on aviation engines
also. Two makes of positively-actuated valves are shown
at Fig. 6. The positive-valve motor differs from the con-
ventional form by having no necessity for valve-springs,
as a cam not only assures the opening of the valve, but
also causes it to return to the valve-seat. In this respect
it is much like the sleeve-valve motor, where the uncover-
ing of the ports is absolutely positive. The cars equipped
with these valves were a success in long-distance auto
races. Claims made for this type of valve mechanism
include the possibility of a higher number of revolutions
and consequently greater engine power. With the spring-
controlled, single-cam operated valve a point is reached
where the spring is not capable of returning the valve

Springless Valves

281

to its seat before the cam has again begun its opening
movement. It is possible to extend the limits consider-
ably by using a light valve on a strong spring, but the

Igriif't-on

Fig. 111. Timing Diagram Showing Peculiar Valve Timing of Gnome
"Monosoupape" Rotary Motor.

valve still remains a limiting factor in the speed of the
motor.

A part sectional view through a cylinder of an engine
designed by G. Michaux is shown at Fig. 112, A. There
are two valves per cylinder, inclined at about ten degrees
from the vertical. The valve-stems are of large diameter,
as owing to positive control, there is no necessity of
lightening this part in an unusual degree. A single over-

282

Aviation Engines

head cam-shaft has eight pairs of cams, which are shown
in detail at B. For each valve there is a three-armed
rocker, one arm of which is connected to the stem of the
valve and the two others are in contact, respectively with
the opening and closing cams. The connection to the
end of the valve-stem is made by a short connecting link,
which is screwed on to the tnd of the valve-stem and

Yoke
Guide

Cam Shaft

Housing

Supports

Cam Shaft Housing
Cam
Valve Operating Yoke

Fig. 112. Two Methods of .Operating Valves by Positive Cam Mechanism
Which Closes as Well as Opens Them.

locked in position. This allows some adjustment to' be
made between the valves and the actuating rocker. It will
be evident, that one cam and one rocker arm produce
the opening of the valve and that the corresponding
rocker arm and cam result in the closing of the valve.
If the opening cam has the. usual convex profile, the clos-
ing cam has a correspondingly concave profile. It will
be noticed that a light valve- spring is shown in drawing.
This is provided to give a final seating to its valve after

Positive Valve Systems 283

it lias been closed by the cam. This is not absolutely
necessary, as an engine has been run successfully with-
out these springs. The whole mechanism is contained
within an overhead aluminum cover.

The positive-valve system used on the De Lage motor
is shown at D. In this the valves are actuated as shown
in sectional views D and E. The valve system is unique
in that four valves are provided per cylinder, two for
exhaust and two for intake. The valves are mounted
side by side, as shown at E, so the double actuator mem-
ber may be operated by a single set of cams. The valve--
operating member consists of a yoke having guide bars
at the top and bottom. The actuating cam works inside
of this yoke. The usual form of cam acts on the lower
portion of the yoke to open the valve, while the concave
cam acts on the upper part to close the valves. In this
design provision is made for expansion of the valve-stems
due to heat, and these are not positively connected to the
actuating member. As shown at E, the valves are held
against the seat by short coil springs at the upper end
of the stem. These are very stiff and are only intended
to provide for expansion. A slight space is left between
the top of the valve-stem and the portion of the operat-
ing member that bears against them when the regular
profile cam exerts its pressure on the bottom of the valve-
operating mechanism. Another novelty in this motor
design is that the cam-shafts and the valve-operating
members are carried in casing attached above the motor
by housing supports in the form of small steel pillars.
The overhead cam-shafts are operated by means of bevel
gearing.

FOUR VALVES PER CYLINDER .: :

Mention has been previously made of the sixteen-
valve four-cylinder Duesenberg motor and its great power
output for the piston displacement. This is made pos-
sible by the superior volumetric efficiency of a motor
provided with four valves in each cylinder instead of

284

Aviation Engines

but two. This principle was thoroughly tried out in rac-
ing automobile motors, and is especially valuable in per-
mitting of greater speed and power output from simple
four- and six-cylinder engines. On eight- and twelve-
cylinder types, it is doubtful if the resulting complica-
tion due to using a very large number of valves would
be worth while. When extremely large valves are used,

---~~-'* Two Small
Valves

'One Large
Valve

Fig. 113. Diagram Comparing Two Large Valves and Four Small Ones
of Practically the Same Area. Note How Easily Small Valves are
Installed to Open Directly Into the Cylinder.

as shown in diagram at Fig. 113, it is difficult to have
them open directly into the cylinder, and pockets are
sometimes necessary. A large valve would weigh more
than two smaller valves having an area slightly larger
in the aggregate; it would require a stiff er valve spring
on account of its greater weight. A certain amount of
metal in the valve-head is necessary to prevent warping;
therefore, the inertia forces will be greater in the large
valve than in the two smaller valves. As a greater port

Multiple Valve Advantages

285

286

Aviation Engines

area is obtained by the use of two valves, the gases will
be drawn into the cylinder or expelled faster than with
a lesser area. Even if the areas are practically the same
as in the diagram at Fig. 113, the smaller valves may

Inlet Valve Depressing Lever

Push Rod

Exhaust Valve
Actuating
Lever.

Cylinder hold

Propeller Hub

Oil Gauge

Oil Pump-

Fig. 115. Front View of Curtiss OX3 Aviation Motor, Showing Uncon-
ventional Valve Action by Concentric Push Rod and Pull Tube.

have a greater lift without imposing greater stresses on
the valve-operating mechanism and quicker gas intake
and exhaust obtained. The smaller valves are not af-
fected by heat as much as larger ones are. The quicker
gas movements made possible, as well as reduction of

Multiple Valve Advantages 287

inertia forces, permits of higher rotative speed, and,
consequently, greater power output for a given piston
displacement. The drawings at Fig. 114 show a sixteen-
valve motor of the four-cylinder type that has been de-
signed for automobile racing purposes, and it is apparent
that very slight modifications would make it suitable for
aviation purposes. Part of the efficiency is due to the
reduction of bearing' friction by the use of ball bearings,
but the multiple-valve feature is primarily responsible
for the excellent performance.

CHAPTER IX

Constructional Details of Pistons Aluminum Cylinders and Pistons
Piston Ring Construction Leak Proof Piston Rings Keeping
Oil Out of Combustion Chamber Connecting Rod Forms Con-
necting Rods for Vee Engines Cam-Shaft and Crank-Shaft De-
signs Ball Bearing Crank-Shafts Engine Base Construction.

CONSTRUCTIONAL DETAILS OF PISTONS

The piston is one of the most important parts of the
gasoline motor inasmuch as it is the reciprocating mem-
ber that receives the impact of the explosion and which
transforms the power obtained by the combustion of gas
to mechanical motion by means of the connecting rod to
which it is attached. The piston is one of the simplest
elements of the motor, and it is one component which
does not vary much in form in different types of motors.
The piston is a cylindrical member provided with a series
of grooves in which packing rings are placed on the out-
side and two bosses which serve to hold the wrist pin in
its interior. It is usually made of cast iron or aluminum,
though in some motors where extreme lightness is de-
sired, such as those used for aeronautic work, it may be
made of steel. The use of the more resisting material
enables the engineer to use lighter sections where it is
important that the weight of this member be kept as low
as possible consistent with strength.

A number of piston types are shown at Fig. 116. That
at A has a round top and is provided with four split
packing rings and. two oil grooves. A piston of this type
is generally employed in motors where the combustion
chamber is large and where it is desired to obtain a
higher degree of compression than would be possible with
a flat top piston. This construction is also stronger be-
cause of the arched piston top. The most common form

Constructional Details of Pistons

289

of piston is that shown at B, and it differs from that
previously described only in that it has a flat top. The
piston outlined in section at C is a type used on some
of the sleeve-valve motors of the Knight pattern, and
has a concave head instead of the convex form shown
at A. The design shown at D in side and plan views is

Side View

Fig. 116. Forms of Pistons Commonly Employed in Gasoline Engines.
A Dome Head Piston and Three Packing Kings. B Flat Top Form
Almost Universally Used. C Concave Piston Utilized in Knight
Motors and Some Having Overhead Valves. D Two-Cycle Engine
Member with Deflector Plate Cast Integrally. E Differential of
Two-Diameter Piston Used in Some Engines Operating on Two-Cycle
Principle.

the conventional form employed in two-cycle engines.
The deflector plate on the top of the cylinder is cast in-
tegral and is utilized to prevent the incoming fresh gases
from flowing directly over the piston top and out of the
exhaust port, which is usually opposite the inlet open-
ing. On these types of two-cycle engines where a two-
diameter cylinder is employed, the piston shown at E is

290

Aviation Engines

fi o I

fl FHO

45*

lifts

.
I -8 B 5

O rt 53 5

p4 fe ai P-i 3

5! If I

Constructional Details of Pistons

291

used. This is known as a "differential piston," and has
an enlarged portion at its lower end which fits the pump-
ing cylinder. The usual form of deflector plate is pro-

Piston Rings

Piston Ring
Grooves

Wrist Pin

Piston

Connecting Rod-

Connecting Rod Bearing

Bearing Liner's
Connecting Rod Cap

Connecting Rod Bolts

Oil Scoop

Fig. 118. Typical Piston and Connecting Rod Assembly.

vided at the top of the piston and one may consider it
as two pistons in one.

One of the important conditions in piston design is
the method of securing the wrist pin which is used to

292

Aviation Engines

connect the piston to the upper end of the connecting
rod. Various methods have been devised to keep the
pin in place, the most common of these being shown at
Fig. 117. The wrist pin should be retained by some
positive means which is not liable to become loose under
the vibratory stresses which obtain at this point. If the

Spark Plugs

Spark

Connecting Rod
Big End Boxes

Pis -ran
Rings-

'-Connecting Rod M/ , n D ,

Wrist Pin Bushing-

Ring Grooves

Piston

Fig. 119. Parts of Sturtevant Aviation Engine. A Cylinder Head
Showing Valves. B Connecting Rod. C Piston and Rings.

Constructional Details of Pistons 293

wrist pin was free to move it would work out of the
bosses enough so that the end would bear against the
cylinder wall. As it is usually made of steel, which is a
harder material than cast iron used in cylinder construc-
tion, the rubbing action would tend to cut a groove in
the cylinder wall which would make for loss of power

Fig. 120. Aluminum Piston and Light But Strong Steel Connecting Rod
and Wrist Pin of Thomas Aviation Engine.

because it would permit escape of gas. The wrist pin
member is a simple cylindrical element that fits the bosses
closely, and it may be either hollow or solid stock. A
typical piston and connecting rod assembly which shows
a piston in section also is given at Fig. 118. The piston
of the Sturtevant aeronautical motor is shown at Fig.
119, the aluminum piston of the Thomas airplane motor
with piston rings in place is shown at Fig. 120. A good
view of the wrist pin and connecting rod are also given.
The iron piston of the Gnome "Monosoupape" airplane
engine and the unconventional connecting rod assembly
are clearly depicted at Fig 121.

The method of retention shown at A is the simplest
and consists of a set screw having a projecting portion

294 Aviation Engines

passing into the wrist pin and holding it in place. The
screw is kept from turning or loosening by means of a
check nut. The method outlined at B is similar to that
shown at A, except that the wrist pin is solid and the
point of the set screw engages an annular groove turned
in the pin for its reception. A very positive method- is
shown at C. Here the retention screws pass into the
wrist pin and are then locked by a piece of steel wire
which passes through suitable holes in the ends. The
method outlined at D is sometimes employed, and it varies

Fig. 121. Cast Iron Piston of "Monosoupape" Gnome Engine Installed
On One of the Short Connecting Eods.

from that shown at C only in that the locking wire, which
is made of spring steel, is passed through the heads of
the locking screws. Some designers machine a large
groove around the piston at such a point that when the
wrist pin is put in place a large packing ring may be
sprung in the groove and utilized to hold the wrist pin
in place.

The system shown at F is not so widely used as the
simpler methods, because it is more costly and does not
offer any greater security when the parts are new than
the simple lock shown at A. In this a hollow wrist pin is
used, having a tapered thread cut at each end. The wrist
pin is slotted at three or four points, for a distance equal
to the length of the boss, and when taper expansion plugs

Piston Pin Retention 295

are screwed in place the ends of the wrist pin are ex-
panded against the bosses. This method has the advan-
tage of providing a certain degree of adjustment if the
wrist pin should loosen up after it has been in use for
some time. The taper plugs would be screwed in deeper
and the ends of the wrist pin expanded proportionately
to take up the loss motion. The method shown at Gf is
an ingenious one. One of the piston bosses is provided
with a projection which is drilled out to receive a plunger.
The wrist pin is provided with a hole of sufficient size to
receive the plunger, which is kept in place by means of
a spring in back of it. This makes a very positive lock
and one that can be easily loosened when it is desired to
remove the wrist pin. To unlock, a piece of fine rod is
thrust into the hole at the bottom of the boss which pushes
the plunger back against the spring until the wrist pin
can be pushed out of the piston.

Some engineers think it advisable to oscillate the wrist
pin in the piston bosses, instead of in the connecting rod
small end. It is argued that this construction gives more
bearing surface at the wrist pin and also provides for
more strength because of the longer bosses that can be
used. When this system is followed the piston pin is
held in place by locking it to the connecting rod by some
means. At H the simplest method is outlined. This con-
sisted of driving a taper pin through both rod and wrist
pin and then preventing it from backing out by putting
a split cotter through the small end of the tapered, lock-
ing pin. Another method, which is depicted at I, consists
of clamping the wrist pin by means of a suitable bolt
which brings the slit connecting rod end together as
shown.

ALUMINUM FOR CYLINDERS AND PISTONS

Aluminum pistons outlined at Fig. 122, have replaced
cast iron members in many airplane engines, as these
weigh about one-third as much as the cast iron forms of
the same size, while the reduction in the inertia forces

296

Aviation Engines

has made it possible to increase the engine speed without
correspondingly stressing the connecting rods, crank-shaft
and engine bearings.

Aluminum has not only been used for pistons, but a
number of motors will be built for the coming season that
will use aluminum cylinder block castings as well. Of
course, the aluminum alloy is too soft to.be used as a
bearing for the piston, and it will not withstand the ham-
mering action of the valve. This makes the use of cast

(-""Ribs

,'Hourglass
\ Piston

Racing
Piston

''Recesses in Casting
Hourglass Piston*.

,Ribs for Strength and
Heat Radiation*

Wrist Pin Boss'"'

Sections of Aluminum Piston

Fig. 122. Types of Aluminum Pistons Used In Aviation Engines,

iron or steel imperative in all motors. When used in con-
nection with an aluminum cylinder block the cast iron
pieces are placed in the mould so that they act as cylinder
liners and valve seats, and the molten metal is poured
around them when the cylinder is cast. It is said that
this construction results in an intimate bond between the
cast iron and the surrounding aluminum metal. Steel
liners may also be pressed into the aluminum cylinders
after these are bored out to receive them. Aluminum
has for a number of years been used in many motor

Aluminum Pistons 297

car parts. Alloys have been developed that have greater
strength than cast iron and that are not so brittle. Its
use for manifolds and engine crank and gear cases has
been general for a number of years.

At first thought it would seem as though aluminum
would be entirely unsuited for use in those portions of
internal combustion engines exposed to the heat of the
explosion, on account of the low melting point of that
metal and its disadvantageous quality of suddenly " wilt-
ing " when a critical point in the temperature is reached.
Those who hesitated to use aluminum on account of this
defect lost sight of the great heat conductivity of that
metal, which is considerably more than that of cast iron.
It was found in early experiments with aluminum pistons
that this quality of quick radiation meant that aluminum
pistons remained considerably cooler than cast iron ones
in service, which was attested to by the reduced forma-
tion of carbon deposits thereon. The use of aluminum
makes possible a marked reduction in power plant weight.
A small four-cylinder engine which was not particularly
heavy even with cast iron cylinders was found to weigh
100 pounds less when the cylinder block, pistons, and
upper half of the crank-case had been made of aluminum
instead of cast iron. Aluminum motors are no longer
an experiment, as a considerable number of these have
been in use on cars during the past year without the
owners of the cars being apprised of the fact. Absolutely
no complaint was made in any case of the aluminum
motor and it was demonstrated, in addition to the saving
in weight, that the motors cost no more to assemble and
cooled much more efficiently than the cast iron form. One
of the drawbacks to the use of aluminum is its growing
scarcity, which results in making it a "near precious"
metal.

PISTON RING CONSTRUCTION

As all pistons must be free to move up and down in
the cylinder with minimum friction, they must be less in

298 Aviation Engines

diameter than the bore of the cylinder. The amount of
freedom or clearance provided varies with the construc-
tion of the engine and the material the piston is made of,
as well as its size, but it is usual to provide from .005 to
.010 of an inch to compensate for the expansion of the
piston due to heat and also to leave sufficient clearance
for the introduction of lubricant between the working
surfaces. "Obviously, if the piston were not provided with
packing rings, this amount of clearance would enable a
portion of the gases evolved when the charge is exploded
to escape by it into the engine crank-case. The packing

Fig. 123. Types of Piston Rings and Ring Joints. A Concentric Ring.
B Eccentrically Machined Form. C Lap Joint Ring. D Butt Joint,
Seldom Used. E Diagonal Cut Member, a Popular Form.

members or piston rings, as they are called, are split
rings of cast iron, which are sprung into suitable grooves
machined on the exterior of the piston, three or four of
these being the usual number supplied. These have suffi-
cient elasticity so that they bear tightly against the cylin-
der wall and thus make a gas-tight joint. Owing to the
limited amount of surface in contact with the cylinder
wall and the elasticity of the split rings the amount of
friction resulting from the contact of properly fitted rings
and. the cylinder is not of enough moment to cause any
damage and the piston is free to slide up and down in
the cylinder bore.

These rings are made in two forms, as outlined at
Fig. 123. The design shown at A is termed a " concentric

Piston Ring Forms 299

ring," because the inner circle is concentric with the
outer one and the ring" is of uniform thickness at all
points. The ring shown at B is called an "eccentric
ring," and it is thicker at one part than at others. It
has theoretical advantages in that it will make a tighter
joint than the other form, as it is claimed its expansion
due to heat is more uniform. The piston rings must be
split in order that they may be sprung in place in the
grooves, and also to insure that they will have sufficient
elasticity to take the form of the cylinder at the different
points in their travel. If the cylinder bore varies by
small amounts the rings will spring out at the points
where the bore is larger than standard, and spring in at
those portions where it is smaller than standard.

It is important that the joint should be as nearly gas-
tight as possible, because if it were not a portion of the
gases would escape through the slots in the .piston rings.
The joint shown at C is termed a "lap joint," because
the ends of the ring are cut in such a manner that they
overlap. This is the approved joint. The butt joint
shown at D is seldom used and is a very poor form, the
only advantage being its cheapness. The diagonal cut
shown at E is a compromise between the very good form
shown at C and the poor joint depicted at D. It is also
widely used, though most constructors prefer the lap
joint, because it does not permit the leakage of gas as
much as the other two types.

There seems to be some difference of opinion relative
to the best piston ring type some favoring the eccentric
pattern, others the concentric form. The concentric ring
has advantages from the lubricating engineer's point of
view; as stated by the Platt & Washburn Company in
their text-book on engine lubrication, the smaller clear-
ance behind the ring possible with the ring of uniform
section is advantageous.

Fig. 124, A, shows a concentric piston ring in its
groove. Since the ring itself is concentric with the
groove, very small clearance between the back of the ring

300

Aviation Engines

and the bottom of its groove may be allowed. Small
clearance leaves less space for ' the accumulation of oil
and carbon deposits. The gasket effect of this ring is
uniform throughout the entire length of its edges, which
is its marked advantage over the eccentric ring. This
type of piston ring rarely burns fast in its groove. There
are a large number of different concentric rings manu-
factured of different designs and of different efficiency.
Figs. 124, B and 124, C show eccentric rings assembled
in the ring groove. It will be noted that there is a large

Cylinder^ .Clearance

learance CyJmder\

Clearance.

Wafer.-'
Jacket

Eccentric Ring-

Fig-. 124. Diagrams Showing Advantages of Concentric Piston Rings.

space between the thin ends of this ring and the bottom
of the groove. This empty space fills up with oil which
in the case of the upper ring frequently is carbonized,
restricting the action of the ring and nullifying its use-
fulness. The edges of the thin ends are not sufficiently
wide to prevent rapid escape of gases past them. In a
practical way this leakage means loss of compression and
noticeable drop in power. When new and properly fitted,
very little difference can be noted between the tightness
of eccentric and concentric rings. Nevertheless, after
several months' use, a more rapid leakage will always
occur past the eccentric than past the concentric. If
continuous trouble with the carbonization of cylinders,
smoking and sooting of spark-plugs is experienced, it is

Leak-Proof Piston Rings 301

a sure indication that mechanical defects exist in the en-
gine, assuming of course, that a suitable oil has been
used. Such trouble can be greatly lessened, if not en-
tirely eliminated, by the application of concentric rings
(lap joint), of any good make, properly fitted into the
grooves of the piston. Too much emphasis canno^ be
put upon this point. If the oil used in the engine is of
the correct viscosity, and serious carbon deposit, smoking,
etc., still result, the only certain remedy then is to have
the cylinders rebored and fitted with properly designed,
oversized pistons and piston rings.

LEAK-PROOF PISTON RINGS

In order to reduce the compression loss and leakage
of gas by the ordinary simple form of diagonal or lap
joint one-piece piston ring a number of compound rings
have been devised and are offered by their makers to
use in making replacements. The leading forms are
shown at Fig. 125. That shown at A is . known as the
"Statite" and consists of three rings, one carried inside
while the other two are carried on the outside. The ring
shown at B is a double ring and is known as the McCad-
den. This is composed of two thin concentric lap joint
rings so disposed relative to each other that the opening
in the inner ring comes opposite to the opening in the
outer ring.

The form shown at C is known as the "Leektite,"
and is a single ring provided with a peculiar form of lap
and dove tail joint. The ring shown at D is known as
the "Dunham" and is of the double concentric type being
composed of two rings with lap joints which are welded
together at a point opposite the joint so that there is no
passage by which the gas can escape. The Burd high
compression ring is shown at E. The joints of these
rings are sealed by means of an H-shaped coupler of
bronze which closes the opening. The ring ends are made
with tongues which interlock with the coupling. The

302

Aviation Engines

ring shown at F is called the "Evertite" and is a three-
piece ring composed of three members as shown in the
sectional view below the ring. The main part or inner
ring has a circumferential channel in which the two outer
rings lock, the resulting cross-section being rectangular
just the same as that of a regular pattern ring. All
three rings are diagonally split and the joints are spaced
equally and the distances maintained by small pins. This

SECTION OF RING F

Fig. 125. Leak-Proof and Other Compound Piston Rings.

results in each joint being sealed by the solid portion of
the other rings.

The use of a number of light steel rings instead of
one wide ring in the groove is found on a number of
automobile power plants, but as far as knowTi, this con-
struction is not used in airplane power plants. It is
contended that where a number of light rings is em-
ployed a more flexible packing means is obtained and the
possibility of leakage is reduced. Eings of this design
are made of square section steel wire and are given a
spring temper. Owing to the limited width the diagonal

Keeping Oil Out of Combustion Chambers 303

cut joint is generally employed instead of the lap joint
which is so popular on wider rings*

KEEPING OIL OUT OF COMBUSTION CHAMBERS

An examination of the engine design that is econom-
ical in oil consumption discloses the use of tight piston
rings, large centrifugal rings on the crank-shaft where it
passes through the case, ample cooling fins in the pistons,
vents between the crank-case chamber and the valve en-
closures, etc. Briefly put, cooling of the oil in this engine
has been properly cared for and leakage reduced to a
minimum. To be specific regarding details of design:
Oil surplus can be kept out of the explosion chambers by
leaving the lower edge of the piston skirt sharp and by
the use of a shallow groove (C), Fig. 126, just below the
lower piston ring. Small holes are bored through the
piston walls at the base of this groove and communicate
with the crank-case. The similarity of the sharp edges
of piston skirt (D) and piston ring to a carpenter's plane
bit, makes their operation plain.

The cooling of oil in the sump (A) can be accom-
plished most effectively by radiating fins on its outer
surface. The lower crank-case should be fully exposed to
the outer air. A settling basin for sediment (B) should
be provided having a cubic content not less than one-
tenth of the total oil capacity as outlined at Fig. 126.
The depth of this basin should be at least 2% inches, and
its walls vertical, as shown, to reduce the mixing of sedi-
ment with the oil in circulation. The inlet opening to
the oil pump should be near the top of the sediment basin
in order to prevent the entrance into the pump with the
oil of any solid matter or water condensed from the prod-
ucts of combustion. This sediment basin should be
drained after every five to seven hours air service of an
airplane engine. Concerning filtering screens there is
little to be said, save that their areas should be ample
and the mesh coarse enough (one- sixteenth of an inch) to

304

Aviation Engines

offer no serious resistance to the free flow of cold or
heavy oil through them; otherwise the oil in the crank-
case may build up above them to an undesirable level.
The necessary frequency of draining and flushing out the
oil sump differs greatly with the age (condition) of the

s--

Sump

Sediment Basin

Fig. 126. Sectional View of Engine Showing Means of Preventing
Oil Leakage By Piston Rings.

engine and the suitability of the oil used. In broad terms,
the oil sump of a new engine should be thoroughly drained
and flushed with kerosene at the end of the first 200

Connecting Rod Forms 305

miles, next at the end of 500 miles and thereafter every
1,000 miles. While these instructions apply specifically
to automobile motors, it is very good practice to change
the oil in airplane engines frequently. In many cases,
the best results have been secured when the oil supply
is completely replenished every five hours that the en-
gine is in operation.

CONNECTING ROD FORMS

The connecting rod is the simple member that joins
the piston to the crank-shaft and which transmits the
power imparted to the piston by the explosion so that it
may be usefully applied. It transforms the reciprocating
movement of the piston to a rotary motion at the crank-
shaft. A typical connecting rod and its wrist pin are
shown at Fig. 120. It will be seen that it has two bear-
ings, one at either end. The small end is bored out to
receive the wrist pin which joins it to the piston, while
the large end has a hole of sufficient size to go on the
crank-pin. The airplane and automobile engine connect-
ing rod is invariably a steel forging, though in marine
engines it is sometimes made a steel or high tensile
strength bronze casting. In all cases it is desirable to
have softer metals than the crank- shaft and wrist pin at
the bearing point, and for this reason the connecting rod
is usually provided with bushings of anti-friction or white
metal at the lower end, and bronze at the upper. The
upper end of the connecting rod may be one piece, be-
cause the wrist pin can be introduced after it is in place
between the bosses of the piston. The lower bearing
must be made in two parts in most cases, because the
crank- shaft cannot be passed through the bearing owing
to its irregular form. The rods of the Gnome engine are
all one piece types, as shown at Fig. 127, owing to the
construction of the " mother " rod which receives the
crank-pins. The complete connecting rod assembly is
shown in Fig. 121, also at A, Fig. 127. The " mother "

306

Aviation Engines

rod, with one of the other rods in place and one about
to be inserted, is shown at Fig. 127, B. The built-up
crank-shaft which makes this construction feasible is
shown at Fig. 127, B,

Some of the various designs of connecting rods that
have been used are shown at Fig. 128. That at A is a
simple form often employed in single-cylinder motors,
having built-up crank-shafts. Both ends of the connect-

Fig. 127. Connecting Rod and Crank-Shaft Construction of Gnome
"Monosoupape" Engine.

ing rod are bushed with a one-piece bearing, as it can
be assembled in place before the crank-shaft assembly is
built up. A built-up crank-shaft such as this type of con-
necting rod would be used with is shown at Fig. 106. The
pattern shown at B is one that has been used to some
extent on heavy work, and is known as the "marine
type." It is made in three pieces, the main portion being
a steel forging having a- flanged lower end to which the
bronze boxes are secured by bolts. The modified marine
type depicted at C is the form that has received the wid-
est application in automobile and aviation engine con-

Connecting Rod Forms

307

308 Aviation Engines

struction. It consists of two pieces, the main member
being a steel drop forging having the wrist-pin bearing
and the upper crank-pin bearing formed integral, while
the lower crank-pin bearing member is a separate forg-
ing secured to the connecting rod by bolts. In this con-
struction bushings of anti-friction metal are used at the
lower end, and a bronze bushing is forced into the upper-
or wrist-pin end. The rod shown at D has also been
widely used. It is similar in construction to the form
shown at C, except that the upper end is split in order
to permit of a degree of adjustment of the wrist-pin
bushing, and the lower bearing cap is a hinged member
which is retained by one bolt instead of two. When it is
desired to assemble it on the crank-shaft the lower cap
is swung to one side and brought back into place when
the connecting rod has been properly located. Sometimes
the lower bearing member is split diagonally instead of
horizontally, such a construction being outlined at E.

In a number of instances, instead of plain bushed
bearings anti-friction forms using ball or rollers have
been used at the lower end. A ball-bearing connecting
rod is shown at F. The big end may be made in one
piece, because if it is possible to get the ball bearing on
the crank-pins it will be easy to put the connecting rod
in place. Ball bearings are not used very often on con-
necting rod big. ends because of difficulty of installation,
though when applied properly they give satisfactory serv-
ice and reduce friction to a minimum. One of the ad-
vantages of the ball bearing is that it requires no adjust-
ment, whereas the plain bushings depicted in the other
connecting rods must be taken up from time to time to
compensate for wear.

This can be done in forms shown at B ? C, D, and E
by bringing the lower bearing caps closer to the upper
one and scraping out the brasses to fit the shaft. A
number of liners or shims of thin brass or copper stock,
varying from .002 inch to .005 inch, are sometimes inter-
posed between the halves of the bearings when it is first

Connecting Rod Types 309

fitted to the crank-pin. As the brasses wear the shims
may be removed and the portions of the bearings brought
close enough together to take up any lost motion that
may exist, though in some motors no shims are provided
and depreciation can be remedied only by installing new
brasses and scraping to fit.

The various structural shapes in which connecting rods
are formed are shown in section at Gr. Of these the I

~Ring Grooves

Connecting Rod
(Forked)

Connecting Rod Bearing
Cap

Fig. 129. Double Connecting Bod Assembly For Use On Single Crank-
Pin of Vee Engine.

section is most widely used in airplane engines, because
it is strong and a very easy hape to form by the drop-
forging process or to machine out of the solid bar when
extra good steel is used. Where extreme lightness is
desired, as in small high-speed motors used for cycle pro-
pulsion, the section shown at the extreme left is often
used. If the rod is a cast member as in some marine en-
gines, the cross, hollow cylinder, or U sections are some-
times used. If the sections shown at the right are em-

310

Aviation Engines

ployed, advantage is often taken of the opportunity for
passing lubricant through the center of the hollow round
section on vertical motors or at the bottom of the U
section, which would be used on a horizontal cylinder
power plant.

Connecting rods of Vee engines are made in two dis-
tinct styles. The forked or "scissors" joint rod assembly

Fig. 130. Another Type of Double Connecting Bod for Vee Engines.

is employed when the cylinders are placed directly op-
posite each other. The "blade" rod, as shown at Fig.
129, fits between the lower ends of the forked rod, which
oscillate on the bearing which encircles the crank-pin.
The lower end of the "blade" rod is usually attached to
the bearing brasses, the ends of the "forked" rod move
on the outer surfaces of the brasses. Another form of
rod devised for use under these conditions is shown at
Fig. 130 and installed in an aviation engine at Fig. 132.
In this construction the shorter rod is attached to a boss
on the master rod by a short pin to form a hinge and to
permit the short rod to oscillate as the conditions die-

Connecting Rod Types

311

312

Aviation Engines

tate. This form of rod can be easily adjusted when the
bearing depreciates, a procedure that is .difficult with the
forked type rod. The best practice, in the writer's opin-

Fig. 132. Part Sectional View of Renault Twelve-Cylinder Water-Cooled
Engine, Showing Connecting Bod Construction and Other Important
Internal Parts.

ion, is to stagger the cylinders and use side-by-side rods
as is done in the Curtiss engine. Each rod may be fitted
independently of the other and perfect compensation for
wear of the big ends is possible.

Cam-Shaft and Crank-Shaft Design 313

CAM-SHAFT AND CRANK-SHAFT DESIGN

Before going extensively into the subject of crank-
shaft construction it will be well to consider cam-shaft
design, which is properly a part of the valve system and
which has been considered in connection with the other
elements which have to do directly with cylinder construc-
tion to some extent. Cam-shafts are usually simple mem-
bers carried at the base of the cylinder in the engine
case of Vee type motors by suitable bearings and having
the cams employed to lift the valves attached at intervals.
A typical cam-shaft design is shown at Fig. 133. Two
main methods of cam-shaft construction are followed

Fig. 133. Typical Cam-Shaft, with Valve Lifting Cams and Gears to
Operate Auxiliary Devices Forged Integrally.

that in which the cams are separate members, keyed and
pinned to the shaft, and the other where . the cams are
formed integral, the latter being the most suitable for
airplane engine requirements.

The cam-shafts shown at Figs. 133 and 134, B, are of
the latter type, as the cams are machined integrally. In
this case not only the cams but also the gears used in
driving the auxiliary shafts are forged integral. This is
a more expensive construction, because of the .high initial
.cost of forging dies as well as the greater expense of
machining. It has ther advantage over the other form in
which the cams are keyed in place in that it is stronger,
and as the cams are a part of the shaft they can never
become loose, as 'might be possible where they are sepa-
rately formed and assembled on a simple shaft.

The importance of the crank-shaft has been previously

314

Aviation Engines

considered, and some of its forms have been shown in
views of the motors presented in earlier portions of this
work. The crank-shaft is one of the parts subjected to
the greatest strain and extreme care is needed in its con-

Fig. 134. Important Parts of Duesenberg Aviation Engine. A Three
Main Bearing Crank-Shaft. B Cam-Shaft with Integral Cams. C
Piston and Connecting Rod Assembly. D Valve Eocker Group.
E Piston. F Main Bearing Brasses.

struction and design, because practically the entire duty
of transmitting the power generated by the motor to the
gearset devolves upon it. Crank-shafts are usually made
of high tensile strength steel of special composition. They
may be made in four ways, the most common being ,from

Crank-Shaft Construction

315

a drop or machine forging which is formed approximately
to the shape of the finished shaft and in rare instances
(experimental motors only) they may be steel castings.
Sometimes they are made from machine f orgings, where
considerably more machine work is necessary than would
be the case where the shaft is formed between dies.
Some engineers favor blocking the shaft out of a solid
slab of metal and then machining this rough blank to
form. In some radial-cylinder motors of the Gnome and

Fig. 135. Showing Method of Making Crank-Shaft. A The Rough Steel
Forging Before Machining. B The Finished Six-Throw, Seven-Bear-
ing Crank-Shaft.

Le Ehone type the crank-shafts are built up of two pieces,
held together by taper fastenings or bolts.

The form of the shaft depends on the number of
cylinders and the form has material influence on the
method of construction. For instance, a four-cylinder
crank-shaft could be made by either of- the methods out-
lined. On the other hand, a three- or six-cylinder shaft
is best made by the machine forging process, because if
drop forged or cut from the blank it will have to be
heated and the crank throws bent around so that the pins
will lie in three planes one hundred and twenty degrees
apart, while the other types described need no further
attention, as the crank-pins lie in planes one hundred
and eighty degrees apart. This can be better understood
by referring to Fig. 135, which shows a six-cylinder shaft
in the rough and finished stages. At A the appearance

316

Aviation Engines

of the machine forging before any of the material is re-
moved is shown, while at B the appearance of the finished
crank-shaft is clearly depicted. The built-up crank-shaft
is seldom used on multiple-cylinder motors, except in

Fig. 136. Showing Form of Crank-Shaft for Twin-Cylinder Opposed

Power Plant.

some cases where the crank-shafts revolve on ball bear-
ings as in some automobile racing engines.

Crank-shaft form will vary with a number of cylinders
and it is possible to use a number of different arrange-
ments of crank-pins and bearings for the same number

Fig. 137. Crank-Shaft of. Thomas-Morse Eight-Cylinder Vee Engine.

of cylinders. The simplest form of crank-shaft is that
used on simple radial cylinder motors as it would consist
of but one crank-pin, .two webs, and the crank-shaft. As
the number of cylinders increase in Vee motors as a gen-
eral rule more crank-pins are used. The crank- shaft that

Crank-Shaft Construction

317

would be used on a two-cylinder opposed motor is shown
at Fig. 136. This has two throws and the crank-pins are
spaced 180 degrees apart. The bearings are exception-
ally long. Four-cylinder crank- shafts may have two,
three or five main bearings and three or four crank-pins.
In some forms of two-bearing crank-shafts, such as used
when four-cylinders are cast in a block, or unit casting,

Fig. 138. Crank-Case and Crank-Shaft Construction for Twelve-Cylinder
Motors. A Duesenberg. B Curtiss.

two of the pistons are attached to one common crank-
pin, so that in reality the crank-shaft has but three crank-
pins. A typical three bearing, four-cylinder crank-shaft
is shown at Fig. 134, A. The same type can be used for
an eight-cylinder Vee engine, except for the greater length
of crank-pins to permit of side by side rods as shown at
Fig. 137. Six cylinder vertical tandem and twelve-cylin-
der Vee engine crank-shafts usually have four or seven
main bearings depending upon the disposition of the
crank-pins and arrangement of cylinders. At Fig. 138, A,

318

Aviation Engines

the bottom view of a twelve-cylinder engine with bottom
half of crank case removed is given. This illustrates
clearly the arrangement of main bearings when the crank-
shaft is supported, on four journals. The crank-shaft
shown at Fig. 138, B. is a twelve-cylinder seven-bearing
type. .

In some automobile engines, extremely good results
have been secured in obtaining steady running with mini-

>Main Bearing No. I

/, Balance weights forged
/ \ integrally with shaft

Main Bearing No.3

-.-Balance weights bolted on

Balance weights-

Fig. 139. Counterbalanced Crank-Shafts Eeduce Engine Vibration and
Permit of Higher Rotative Speeds.

mum vibration by counterbalancing the crank-shafts as
outlined at Fig. 139. The shaft at A is a- type suitable
for a high speed four-cylinder vertical or an eight-cylin-
der Vee type. That at B is for a six-cylinder vertical or
a twelve-cylinder V with scissors joint rods. If counter-
balancing crank-shafts helps in an automobile engine, it
should have advantages of some moment in airplane en-
gines, even though the crank-shaft weight is greater.

B all-Bearing Crank-Shafts 319

BALL-BEARING CRANK-SHAFTS

While crank-shafts are usually supported in plain
journals there seems to be a growing tendency of late
to use anti-friction bearings of the ball type for their
support. This is especially noticeable on block motors
where but two main bearings are utilized. When ball
bearings are selected with proper relation to the load
which obtains they will give very satisfactory service.
They permit the crank- shaft to turn with minimum fric-
tion, and if properly selected will never need adjustment.
The front end is supported by a bearing which is clamped
in such a manner that it will take a certain amount of
load in a direction parallel to the axis of the shaft, while
the rear end is so supported that the outer race of the
bearing has a certain amount of axial freedom or "float."
The inner race or cone of each bearing is firmly clamped
against shoulders on the crank-shaft. At the front end
of the crank- shaft timing gear and a suitable check nut
are used, while at the back end the bearing is clamped
by a threaded retention member between the fly-wheel
and a shoulder on the crank-shaft. The fly-wheel is held
in place by a taper and key retention. The ball bearings
are carried in a light housing of bronze or malleable iron,
which in turn are held in the crank-case by bolts. The
Kenault engine uses ball bearings at front and rear ends
of the crank-shaft, but has plain bearings around inter-
mediate crank-shaft journals. The rotary engines of the
Gnome, Le Rhone and Clerget forms would not be prac-
tical if ball bearings were not used as the bearing fric-
tion and consequent depreciation would be very high.

ENGINE-BASE CONSTRUCTION

One of the important parts of the power plant is the
substantial casing or bed member, which is employed to
support the cylinders and crank-shaft and which is at-
tached directly to the fuselage engine supporting mem-

320 Aviation Engines

bers. This will vary widely in form, but as a general
thing it is an approximately cylindrical member which
may be divided either vertically or horizontally in two
or more parts. Airplane engine crank-cases are usually
made of aluminum, a material which has about the same
strength as cast iron, but which only weighs a third as
much. In rare cases cast iron is employed, but is not
favored by most engineers because of its brittle nature,

Fig. 140. View of Thomas 135 Horse-Power Aeromotor, Model 8, Showing
Conventional Method of Crank-Case Construction.

great weight and low resistance to tensile stresses. Where
exceptional strength is needed alloys of bronze may be
used, and in some cases where engines are produced in
large quantities a portion of the crank-case may be a
sheet steel or aluminum stamping.

Crank-cases are always large enough to permit the
crank-shaft and parts attached to it to turn inside and
obviously its length is determined by the number of cylin-
ders and their disposition. The crank-case of the radial
cylinder or double-opposed cylinder engine would be sub-
stantially the same in length. That of a four-cylinder

Crank-Case Construction

321

will vary in length with the method of casting the cylin-
der. When the four-cylinders are cast in one unit and
a two-bearing crank-shaft is used, the crank-case is a very

Fig. 141. Views of Upper Half of Thomas Aeromotor Crank-Case.

compact and short member. When a three-bearing crank-
shaft is utilized and the cylinders are cast in pairs, the
engine base is longer than it would be to support a block
casting, but is shorter than one designed to sustain in-

322

Aviation Engines

dividual cylinder castings and a five-bearing crank-shaft.
It is now common construction to cast an oil container
integral with the bottom of the engine base and -to draw
the lubricating oil from it by means of a pump, as shown
at Fig. 140. The arms by which the motor is supported

Inlet Ports
Exhaust Ports .

Exhaust

Right Hand Cylinder Block
Note: Rigidity and t cleanliness of design
also central inlet port locations
for even distribution of gas

Exhaust Ports r ..

Inlet Ports
Exhaust Ports - A

,(9/7 Duct to Cam Shaft

\ Bearing and Front

Gear Case

''Crank Shaft Bearing
Oil Ports

'Oil Return /y f e . Bearing Supports

Left Hand Cylinder Block Casting

Fig. 142. Method of Constructing Eight-Cylinder Vee Engine, Possible
if Aluminum Cylinder and Crank-Case Castings are Used.

C rank-Case Construction 323

in the fuselage are substantial-ribbed members cast inte-
grally with the upper half.

The approved method of crank-case construction fa-
vored by the majority of engineers is shown at the top of
Fig. 141, bottom side up. The upper half not only forms
a bed for the cylinder but is used to hold the crank-shaft
as well. In the illustration, the three-bearing boxes form
part of the case, while the .lower brasses are in the form

Fig. 143. Simple and Compact Crank-Case, Possible When Radial Cylinder
Engine Design is Followed.

of separately cast caps retained by suitable bolts. In
the construction outlined the bottom part of the case
serves merely as an oil container and a protection for
the interior, mechanism of the motor. The cylinders are
held down by means of studs screwed into the crank-case
top, as shown at Fig. 141, lower view. If the aluminum
cylinder motor has any future, the method of construc-
tion outlined at Fig. 142, which has been used in cast iron
for an automobile motor, might be used for an eight-
cylinder Vee engine for airplane use. The simplicity of
the crank-case needed for a revolving cylinder motor
and its small weight can be well understood by examina-
tion of the illustration at Fig. 143, which shows the en-
gine crank-case for the nine-cylinder "Monosoupape"
Gnome engine. This consists" of two accurately machined
forgings held together by bolts as clearly indicated.

CHAPTER X

Power Plant Installation Curtiss OX 2 Engine Mounting and Operating
Rules Standard S. A. E. Engine Bed Dimensions Hall-Scott
Engine Installation and Operation Fuel System Rules Ignition
System Water System: Preparations to Start Engine Mounting
Radial and Rotary Engines Practical Hints to Locate Engine
Troubles All Engine Troubles Summarized Location of Engine
Troubles Made Easy.

The proper installation of the airplane power plant
is more important than is generally supposed, as while
these engines are usually well balanced and run with little
vibration, it is necessary that they be securely anchored
and that various connections to the auxiliary parts be
carefully made in order to prevent breakage from vibra-
tion and that attendant risk of motor stoppage while in
the air. The type of motor to be installed determines
the method of installation to be followed. As a general
rule six-cylinder vertical engine and eight-cylinder Vee
type are mounted in substantially the same way. The
radial, fixed cylinder forms and the radial, rotary cylin-
der Gnome and Ehone rotary types require an entirely
different method of mounting. Some unconventional
mountings have been devised, notably that shown at Fig.
144, which is a six-cylinder German engine that is in-
stalled in just the opposite way to that commonly fol-
lowed. The inverted cylinder construction is not gen-
erally followed because even with pressure feed, dry
crank-case type lubricating system there is considerable
danger of over-lubrication and of oil collecting and car-
bonizing in the combustion chamber and gumming up
the valve action much quicker than would be the case if
the engine was operated in the conventional upright posi-
tion. The reason for mounting an engine in this way is
to obtain a lower center of gravity and also to make for

324

Power Plant Installation

325

more perfect streamlining of the front end of the fuselage
in some cases. It is rather doubtful if this slight ad-
vantage will compensate for the disadvantages intro-
duced by this unusual construction. It is not used to
any extent now but is presented merely to show one of
the possible systems of installing an airplane engine.

In a number of airplanes of the tractor-biplane type
the power plant installation is not very much different

r i ** jk --, \

\ slk^^^^^^>. ! / /

Fig. 144. Unconventional Mounting of German Inverted Cylinder Motor.

than that which is found in automobile practice. The
illustration at Fig. 145- is a very clear representation of
the method of mounting the Curtiss eight-cylinder 90
H. P. or model 0X2 engine in the fuselage of the Curtiss
JN4 tractor biplane which is so generally used in the
United States as a training machine. It will be observed
that the fuel tank is mounted under a cowl directly behind
the motor and that it feeds the carburetor by means of a

326

Aviation Engines

flexible fuel pipe. As the tank is mounted higher than the
carburetor, it will feed that member by gravity. The
radiator is mounted at the front end of the fuselage and
connected to the water piping on the motor ,by the usual
rubber hose connections. An oil pan is placed under the
engine and the top is covered with a hood just as in
motor car practice. The panels of aluminum are attached

Fig. 145. How Curtiss Model OX2 Motor is Installed in Fuselage of
Curtiss Tractor Biplane. Note Similarity of Mounting to Automobile
Power Plant.

to the sides of the fuselage and are supplied with doors
which open and provide access to the carburetor, oil-
gauge and other parts of the motor requiring inspection.
The complete installation with the power plant enclosed
is given at Fig. 146, and in this it will be observed that
the exhaust pipes are connected to discharge members
that lead the gases above the top plane. In the engine
shown at Fig. 145 the exhaust flows' directly into the air
at the sides of the machine through short pipes bolted to
the exhaust gas outlet ports. The installation of the

327

328

Aviation Engines

radiator just back of the tractor screw insures that ade-
quate cooling will be obtained because of the rapid air
flow due to the propeller slip stream.

INSTALLATION OF CURTISS OX 2 ENGINE

The following instructions are given in the Curtiss
Instruction Book for installing the 0X2 engine and pre-
paring it for flights, and taken in connection with the very

Flexible Exhaust Discharge Pipes

/r Exhaust Manifolds

Radiator,

Fig. 147. Front View of L. W. F. Tractor Biplane Fuselage, Showing
Method of Installing Thomas Aeromotor and Method of Disposing of
Exhaust Gases.

clear illustration presented no difficulty should be experi-
enced in understanding the proper installation, and mount-
ing of this power plant. The bearers or beds should be
2 inches wide by 3 inches deep, preferably of laminated
hard wood, and placed 11% inches apart. They must be
well braced. The six arms of the base of the motor are

Curtis OX2 Engine Installation 329

drilled for %-inch bolts, and none but this size should
be used.

1. Anchoring the Motor. Put the bolts in from the
bottom, with a large washer under the head of each so
the head cannot cut into the wood. On every bolt use a
castellated nut and a cotter pin, or an ordinary nut and
a lock washer, so the bolt will not work loose. Always
set motor in place and fasten before attaching any aux-
iliary apparatus, such as carburetor, etc.

2. Inspecting the Ignition-Sivitch Wires. The wires
leading from the ignition switch must be properly con-
nected one end to the motor body for ground, and the
other end to the post on the breaker box of the magneto.

3. Filling the Radiator. Be sure that the water from
the radiator fills the cylinder jackets. Pockets of air
may remain in the cylinder jackets even though the
radiator may appear full. Turn the motor over a few
times by hand after filling the radiator, and then add
more water if the radiator will take it. The air pockets,
if allowed to remain, may cause overheating and develop
serious trouble when the motor is running.

4. Filling the Oil Reservoir. Oil is admitted into the
crank-case through the breather tube at the rear. It is
well to strain all oil put into the crank-case. In filling the
oil reservoir be sure to turn the handle on the oil sight-
gauge till it is at right angles with the gauge. The oil
sight-gauge is on the side of the lower half of the crank-
case. Put in about 3 gallons of the best obtainable oil,
Mobile B recommended. It is important to remember
that the very best oil is none too good.

5. Oiling Exposed Moving Parts. Oil all rocker-arm
bearings before each flight. A little oil should be applied
where the push rods pass through the stirrup straps.

6. Filling the Gasoline Tanks. Be certain that all
connections in the gasoline system are tight.

7. Turning on the Gasoline. Open the cock leading
from the gasoline tank to the carburetor.

8. Charging the Cylinders. With the ignition switch

330 Aviation Engines

OFF, prime the motor by squirting a little gasoline in
each exhaust port and then turn the propeller backward
two revolutions. Never open the exhaust valve by oper-
ating the rocker-arm by hand, as the push-rod is liable to
come out of its socket in the cam follower and bend the
rocker-arm when the motor turns over.

9. Starting the Motor Toy Hand. Always retard the
spark part way, to prevent back-firing, by pulling for-
ward the wire attached. to the breaker box. Failure to so
retard the spark in starting may result in serious injury
to the operator. Turn on the ignition switch with throttle
partly open; give a quick, strong pull down and outward
on the starting crank or propeller. As soon as the motor
is started advance the spark by releasing the retard wire.

10. Oil Circulation. Let the motor run at low speed
for a few minutes in order to establish oil circulation in
all bearings. With all parts functioning properly, the
throttle may be opened gradually for warming up before
flight.

* STANDAKD S.A.E. ENGINE BED DIMENSIONS

The Society of Automotive Engineers have made ef-
forts to standardize dimensions of bed timbers for sup-
porting power plant in an aeroplane. Owing to the great
difference in length no standardization is thought possible
in this regard. The dimensions recommended are as
follows :

Distance between timbers ....... 12 in. 14 in. 16 in.

Width of bed timbers .......... 1 % in. 1 % in. 2 in.

Distance between centers of bolts. IS 1 ^ in. 15% in. 18 in.

It will be evident that if any standard of this nature
were adopted by engine builders that the designers of
fuselage could easily arrange their bed timbers to con-
form to these dimensions, whereas it would be difficult to
have them adhere to any standard longitudinal dimen-
sions which are much more easily varied in fuselages
than the transverse dimensions are. It, however, should

Standard Engine Bed Dimensions

331

d Y

332

Aviation Engines

be possible to standardize the longitudinal positions of
the holding down bolts as the engine designer would still
be able to allow himself considerable space fore-and-aft
of the bolts.

HALL-SCOTT ENGINE INSTALLATION

The very thorough manner in which installation dia-
grams are prepared by the leading engine makers leaves
nothing to the imagination. The dimensions of the Hall-
Scott four-cylinder airplane engine are given clearly in

Fig. 149. Plan and Side Elevation of HaU-Scott A-7 Four-Cylinder Air-
plane Engine, with Installation Dimensions.

Engine Installation 333

our inch measurements with the metric equivalents at
Figs. 148 and 149, the former showing a vertical eleva-
tion while the latter has a plan view and side elevation.
The installation of this engine in airplanes is clearly
shown at Figs. 150 and 151, the former having the radi-
ator installed at the front of the motor and having all
exhaust pipes joined to one common discharge funnel,

Fig. 150.

CENSORED

which deflects the gas ove'r the top plane while the latter
has the radiator placed vertically above the motor at
the back end and has a direct exhaust gas discharge to
the air.

The dimensions of the, six-cylinder Hall-Scott motor
which is known as the type A-5 125 H. P. are given at
Fig. 152, which is an end sectional elevation, and at Fig.
153, which is a plan view. The dimensions are given both
in inch sizes and the metric equivalents. The appearance

334 Aviation Engines

of a Hall-Scott six-cylinder engine installed in a fuselage
is given at Fig. 154, while a diagram showing the loca-
tion of the engine and the various pipes leading to the
auxiliary groups is outlined at Fig. 155. The following
instructions for installing the Hall-Scott power plant are

Fig. 151.

CENSORED

Engine Installation 335

Fig. 152.

CENSORED

336

Aviation Engines

reproduced from the instruction book issued by the maker.
Operating instructions which are given should enable any
good mechanic to make a proper installation and to keep
the engine in good running condition.

FUEL SYSTEM INSTALLATION

Gasoline giving the best results with this equipment
is as follows: Gravity 58-62 deg. Baume A. Initial boil-
ing point Eichmond method 102 Fahr. Sulphur .014.

" -A*-- 6'/z"-*#"6'/ 2 "~l\

"* I/I /6*- J/1/65MW.J/

Fig. 153. Plan View of Hall-Scott Type A-5 125 Horse-Power Airplane
Engine, Showing Installation Dimensions.

Calorimetric bomb test 20610 B. T. IL per pound. If the
gasoline tank is placed in the fuselage below the level of
the carburetor, a hand pump must be used to maintain
air pressure in gas tank to force the gasoline to the car-
buretor. After starting the engine the small auxiliary air
pump upon the engine will maintain sufficient pressure.
A-7a and A-5a engines are furnished with a new type
auxiliary air pump. This should be frequently oiled and
care taken so no grit or sand will enter which might lodge
between the valve and its seat, which would make it fail
to operate properly. An air relief valve is furnished with
each engine. It should be screwed into the gas tank and
properly regulated to maintain the pressure required.

Hall-Scott Engine Installation

337

This is done by screwing the ratchet on top either up or
down. If two tanks are used in a plane one should be
installed in each tank. All air pump lines should be care-

Fig. 154. Three-Quarter View of Hall-Scott Type A-5 125 Horse-Power
Six-Cylinder Engine, with One of the Side Radiators Removed to
Show Installation in Standard Fuselage.

338

Engine Installation 339

fully gone over quite frequently to ascertain if they are
tight. Check values have to be placed in these lines. In
some cases the gasoline tank is placed above the engine,
allowing it to drain by gravity to the carburetor. When
using this system there should be a drop of .not less than
two feet from the lowest portion of the gasoline tank to
the upper part of the carburetor float chamber. Even
this height might not be sufficient to maintain the proper
volume of gasoline to the carburetor at high speeds. Air
pressure is advised upon all tanks to insure the proper
supply of gasoline. When using gravity feed without
air pressure be sure to vent the tank to allow circulation
of air. If gravity tank is used and the engine runs satis-
factorily at low speeds but cuts out at high speeds the
trouble is undoubtedly due to insufficient height of the
tank above the carburetor. The tank should be raised or
air pressure system used.

IGNITION SWITCHES

Two " DIXIE" switches are furnished with each en-
gine. Both of these should be installed in the pilot's
seat, one controlling the E. H., and the other the L. H.
magneto. By shorting either one or the other it can be
quickly determined if both magnetos, with their respec-
tive spark-plugs, are working correctly. Care should be
taken not to use spark-plugs having special extensions or
long protruding points. Plugs giving best results are ex-
tremely small with short points.

WATER SYSTEMS

A temperature gauge should be installed in the water
pipe, coming directly from the cylinder nearest the pro-
peller (note illustration above). This instrument in-
stalled in the radiator cap has not always given satis-
factory results. This is especially noticeable when the
water in the radiator becomes low, not allowing it to
touch the bulb on the moto-meter. For ordinary running,

340 Aviation Engines

it should not indicate over 150 degrees Fahr. In climb-
ing tests, however, a temperature of 160 degrees Fahr.
can be maintained without any ill effects upon the en-
gine. In case the engine becomes overheated, the indi-
cator will register above 180 degrees Fahr., in which case
it should be stopped immediately. Overheating is most
generally caused by retarded spark, excessive carbon in
the cylinders, insufficient lubrication, improperly timed
valves, lack of water, clogging of water system in any
way which would obstruct the free circulation of the
water.

Overheating will cause the engine to knock, with pos-
sible damaging results. Suction pipes should be made
out of thin tubing, and run within a quarter or an eighth
of an inch of each other, so that when a hose is placed
over the two, it will not be possible to suck together.
This is often the case when a long rubber hose is used,
which causes overheating. Eadiators should be flushed
out and cleaned thoroughly quite often. A dirty radiator
may cause overheating.

When filling the radiator it is very important to re-
move the plug on top of the water pump until water
appears. This is to avoid air pockets being formed in the
circulating system, which might not only heat up the
engine, but cause considerable damage. All water pump
hoses and connections should be tightly taped and shel-
lacked after the engine is properly installed in the plane.
The greatest care should be taken when making engine
installation not to use . smaller inside diameter hose con-
nection than water pump suction end casting. One inch
and a quarter inside diameter should be used on A-7 and
A-5 motors, while nothing less than one inch and a half
inside diameter hose or tubing on all A-7a and A-5a en-
gines. It is further important to have light spun tubing,
void of any sharp turns, leads from pump to radiator and
cylinder water outlet to radiator. In other words, the
water circulation through the engine must be as little
restricted as possible. Be sure no light hose is used, that

Preparations to Start Engine 341

will often suck together when engine is started. To thor-
oughly drain the water from the entire system, open the
drain cock at the lowest side of the water pump.

PREPARATIONS TO START ENGINE

Always replenish gasoline tanks through a strainer
which is clean. This strainer must catch all water and
other impurities in the gasoline. Pour at least three
gallons of fresh oil into the lower crank-case. Oil all
rocker arms through oilers upon rocker arm housing caps.
Be sure radiators are filled within one inch of the top.

After all the parts are oiled, and the tanks filled, the
following must be looked after before starting: See if
crank-shaft flange is tight on shaft. See if propeller bolts
are tight and evenly drawn up. See if propeller bolts are
wired. See if propeller is trued up tp within %".

Every four days the magnetos should be oiled if the
engine is in daily use.

Every month all cylinder hold-down nuts should be
gone over to ascertain if they are tight. (Be sure to re-
cotter nuts.)

See if magnetos are bolted on tight and wired.

See if magneto cables are in good condition.

See if rocker arm tappets have a .020" clearance from
valve stem when valve is seated.

See if tappet clamp screws are tight and cottered.

See if all gasoline, oil, water pipes and connections are
in perfect condition.

Air on gas line should be tested for leaks.

Pump at least three pounds air pressure into gasoline
tank.

After making sure that above rules have been ob-
served, test compression of cylinders by turning propeller.

"DO NOT FORGET TO SHORT BOTH MAGNETOS "

Be sure all compression release and priming cocks do
not leak compression. If they do, replace same with a

342 Aviation Engines

new one immediately, as this might cause premature
firing.

Open priming cocks and squirt some gasoline into each.

Close cocks.

Open compression release cocks.

Open throttle slightly.

If using Berling magnetos they should be three-quar-
ters advanced.

If all the foregoing directions have been carefully
followed, the engine is ready for starting.

In cranking engine either by starting crank, or pro-
peller, it is essential to throw it over compression quickly.

Immediately upon starting, close compression release
cocks.

When engine is running, advance magnetos.

After it has warmed up, short one magneto and then
the other, to be sure both magnetos and spark-plugs are
firing properly. If there is a miss, the fouled plug must
be located and cleaned. There is a possibility that the
jets in the carburetor are stopped up. If this is the case,
do not attempt to clean same with any sharp instrument.
If this is done, it might change the opening in the jets,
thus spoiling the adjustment. Jets and nozzles should
be blown out with air or steam.

An open intake or exhaust valve, which might have
become sluggish or stuck from carbon, might cause
trouble. Be sure to remedy this at once by using a little
coal-oil or kerosene on same, working the valve by hand
until it becomes free. We recommend using graphite on
valve stems mixed with oil to guard against sticking or
undue wear.

INSTALLING ROTARY AND RADIAL CYLINDER ENGINES

When rotary engines are installed simple steel stamp-
ing or "spiders" are attached to the fuselage to hold the
fixed crank-shaft. Inasmuch as the motor projects clear
of the fuselage proper there is plenty of room back of

M W
|S

343

344

Aviation Engines

the front spider plate to install the auxiliary parts such
as the oil pump, air pump and ignition magneto and also
the fuel and oil containers. The diagram given at Fig.
156 shows how a Gnome "monosoupape" engine is in-
stalled on the anchorage plates and it also outlines clearly
the piping necessary to convey the oil and fuel and also
the air-piping needed to put pressure on both fuel and
oil tanks to insure positive supply of these liquids which

: Air Screw

Motor in
Front

Tractor Screw
in Front

*'Motor in Rear

Fig. 157. Showing Two Methods of Placing Propeller on Gnome Rotary

Motor.

may be carried in tanks placed lower than the motor in
some installations. The diagram given at Figs. 157 and
158 shows other mountings of Gnome engines and are
self-explanatory. The simple mounting possible when the
Anzani ten-cylinder radial fixed type engine is used given
at Fig. 159. The front end of the fuselage is provided
with a substantial pressed steel plate having members
projecting from it which may be bolted to the longer-
ons. The bolts that hold the two halves of the crank-
case together project through the steel plate and hold the
engine securely to the front end of the fuselage.

Location of . Engine Troubles

345

PRACTICAL HINTS TO LOCATE ENGINE TROUBLES

One who is not thoroughly familiar with engine con-
struction will seldom locate troubles by haphazard experi-
menting and it is only by a systematic search that the
cause can be discovered and the defects eliminated. In
this chapter the writer proposes to outline some of the
most common power-plant troubles and to give sufficient

Upper
Longeron

'Front Engine
Upper Support

^ Longerons-,^

Rear Engine Support
.Crank-Shaft

^=
'Carburetor"

Tractor Screw

Side View

'-Lower
Longeron

*~- Lower Longerons-'
Front View

Fig. 158. How Gnome Eotary Motor May Be Attached to Airplane

Fuselage Members.

advice to enable those who are not thoroughly informed
to locate them by a logical process of elimination. The
internal-combustion motor, which is the power plant of
all gasoline automobiles as well as airplanes, is composed
of a number of distinct groups, which in turn include dis-
tinct components. These various appliances are so closely
related to each other that defective action of any one may
interrupt the operation of the entire power plant. Some
of the auxiliary groups are more necessary than others
and the power -plant will continue to operate for a time
even after the failure of some important parts of some
of the auxiliary groups. The gasoline engine in itself is

346

Aviation Engines

a complete mechanism, but it is evident that it cannot
deliver any power without some means of supplying gas
to the cylinders and igniting the compressed gas charge
after it has been compressed in the cylinders. From this

Fixed Cylinder
Radial Engine

Engine \
Supporting J~
P/ai-e )

Fig. 159. How Anzani Ten-Cylinder Eadial Engine is Installed to Plate
Securely Attached to Front End of Tractor Airplane Fuselage.

Typical Engine Stoppage Analyzed 347

it is patent that the ignition and carburetion systems are
just as essential parts of the power plant as the piston,
connecting rod, or cylinder of the motor. The failure of
either the carburetor or igniting means to function prop-
erly will be immediately apparent by faulty action of the
power plant.

To insure that the motor will continue to operate it
is necessary to keep it from overheating by some form of
cooling system and to supply oil to the moving parts to
reduce friction. The cooling and lubrication groups are
not so important as carburetion and ignition, as the en-
gine would run for a limited period of time even should
the cooling system fail or the oil supply cease. It would
only be a few moments, however, before the engine would
overheat if the cooling system was at fault, and the parts
seize if the lubricating system should fail. Any derange-
ment in the carburetor or ignition mechanism would man-
ifest itself at once because the engine operation would be
affected, but a defect in the cooling or oiling system would
not be noticed so readily.

The careful aviator will always inspect the motor
mechanism before starting on a trip of any consequence,
and if inspection is carefully carried out and loose parts
tightened it is seldom that irregular operation will be
found due to actual breakage of any of the components
of the mechanism. Deterioration due to natural causes
matures slowly, and sufficient warning is always given
when parts begin to wear so satisfactory repairs may be
promptly made before serious derangement or failure is
manifested.

A TYPICAL ENGINE STOPPAGE ANALYZED

Before describing the points that may fail in the vari-
ous auxiliary systems it will be well to assume a typical
case of engine failure and show the process of locating
the trouble in a systematic manner by indicating the
various steps which are in logical order and which could

348

Aviation Engines

reasonably be followed. In any case of engine failure the
ignition system, motor compression, and carburetor should
be tested first. If the ignition system is functioning prop-
erly one should determine the amount of compression in
all cylinders and if this is satisfactory the carbureting
group should be tested. If the ignition system is working
properly and there is a decided resistance in the cylinders

UJ LJ LJ

"-assas. 35-~**

Fig. 160. Side Elevation of Thomas 135 Horse-Power Airplane Engine,
Giving Important Dimensions.

when the propeller is turned, proving that there is good
compression, one may suspect the carburetor.

If the carburetor appears to be in good condition, the
trouble may be caused by the ignition being out of time,
which condition is possible when the magneto timing gear
or coupling is attached to the armature shaft by a taper
and nut retention instead of the more positive key or
taper-pin fastening. It is possible that the inlet manifold
may be broken or perforated, that the exhaust valve is
stuck on its seat because of a broken or bent stem, broken
or loose cam, or failure of the cam-shaft drive because
the teeth are stripped from the engine shaft or cam-shaft

Engine Troubles Summarized

349

gears; 'or because the key or other fastening on either
gear has failed, allowing that member to turn independ-
ently of the shaft to which it normally is attached. The
gasoline feed pipe may be clogged or broken, the fuel

Fig. 161. Front Elevation of Thomas-Morse 135 Horse-Power Aeromotor,
Showing Main Dimensions.

supply may be depleted, or the shut-off cock in the gaso-
line line may have jarred closed. The gasoline filter may
be filled with dirt or water which prevents passage of the
fuel.

The defects outlined above, except the failure of the

350 Aviation Engines

gasoline supply, are very rare, and if the container is
found to contain fuel and the pipe line to be clear to the
carburetor, it is safe to assume the vaporizing device is
at fault. If fuel continually runs out of the mixing cham-
ber 'the carburetor is said to be flooded. This condition
results from failure of the shut-off needle to seat properly
or from a punctured hollow metal float or a gasoline-
soaked cork float. It is possible that not enough gasoline
is present in the float chamber. If the passage controlled
by the float-needle valve is clogged or if the float was
badly out of adjustment, this contingency would be prob-
able. When the carburetor is examined, if the gasoline
level appears to be at the proper height, one may suspect
that a particle of lint, or dust, or fine scale, or rust from
the gasoline tank has clogged the bore of the jet in the
mixing chamber.

If the ignition system and carburetor appear to be in
good working order, and the hand crank shows that there
is no compression in one or more of the cylinders, it
means some defect in the valve system. If the engine is
a multiple-cylinder type and one finds poor compression
in all of the cylinders it may be due to the rare defect
of improper valve timing. This may be caused by a gear
having altered its position on the cam-shaft or crank-
shaft, because of a sheared key or pin having permitted
the gear to turn about half of a revolution and then
having caught and held the gear in place by a broken or
jagged end so that cam-shaft would turn, but the valves
open at the wrong time. If but one of the cylinders is
at fault and the rest appear to have good compression
the trouble may be due to a defective condition either in-
side or outside of that cylinder. The external parts may
be inspected easily, so the following should be looked for :
a broken valve, a warped valve-head, broken valve-springs,
sticking or bent valve-stems, dirt under valve-seat, leak
at valve-chamber cap or spark-plug gasket. .Defective
priming cock, cracked* cylinder head (rarely occurs), leak
through cracked spark - plug insulation, valve - plunger

351

352 Aviation Engines

stuck in the guide, lack of clearance between valve-stem
end and top of plunger caused by loose adjusting screw
which has worked up and kept the valve from seating.
The faulty compression may be due to defects inside the
motor. The piston-head may be cracked (rarely occurs),
piston rings may be broken, the slots in the piston rings
may be in line, the rings may have lost their elasticity
or have become gummed in the groves of the piston, or
the piston and cylinder, walls may be badly scored by a
loose wrist pin or by defective lubrication. If the motor
is a type with a separate head it is possible the gasket
or packing between the cylinder and combustion chamber
may leak, either admitting water to the cylinder or allow-
ing compression to escape.

CONDITIONS THAT CAUSE FAILURE OF IGNITION SYSTEM

If the first test of the motor had showed that the com-
pression was as it should be and that there were no seri-
ous mechanical defects and there was plenty of gasoline
at the carburetor, this would have demonstrated that the
ignition system was not functioning properly. If a bat-
tery is employed to supply current the first step is to take
the spark-plugs out of the cylinders and test the system
by turning over the engine by hand. If there is no spark
in any of the plugs, this may be considered a positive
indication that there is a broken main current lead from
the battery, a defective ground connection, a loose bat-
tery terminal, or a broken connector. If none of these
conditions are present, it is safe to say that the battery
is no longer capable of delivering current. While mag-
neto ignition is generally used on airplane engines, there
is apt to be some development of battery ignition, espe-
cially on engines equipped with electric self-starters which
are now being experimented with. The spark-plugs may
be short circuited by cracked insulation or carbon and
oil deposits around the electrode. The secondary wires
may be broken or have defective insulation which permits

Ignition System Failure 353

the current to ground to some metal part of the fuselage
or motor. The electrodes of the spark-plug may be too
far apart to permit a spark to overcome the resistance
of the compressed gas, even if a spark jumps the air
space, when the plug is laid on the cylinder.

If magnetos are fitted as is usually the case at present
and a spark is obtained between the points of the plug
and that device or the wire leading to it from the magneto
is in proper condition, the trouble is probably caused by
the magneto being out of time. This may result if the
driving gear is loose on the armature-shaft or crank-
shaft, and is a rare occurrence. If no spark is produced
at the plugs the secondary wire may be broken, the ground
wire may make contact with some metallic portion of the
chassis before it reaches the switch, the carbon collecting
brushes may be broken or not making contact, the contact
points of the make-and-break device may be out of adjust-
ment, the wiring may be attached to wrong terminals, the
distributor filled with metallic particles, carbon, dust or
oil accumulations, the distributor contacts may not be
making proper connection because of wear and there may
be a more serious derangement, such as a burned out
secondary winding or a punctured condenser.

If the motor runs intermittently, i.e., starts and runs
only a few revolutions, aside from the conditions pre-
viously outlined, defective operation may be due to seiz-
ing between parts because of insufficient oil or deficient
cooling, too much oil in the crank-case which fouls the
cylinder after the crank-shaft has revolved a few turns,
and derangements in the ignition or carburetion systems
that may be easily remedied. There are a number of
defective conditions which may exist in the ignition group,
that will result in "skipping" or irregular operation and
the following points should be considered first: weak
source of current due to worn out dry cells or discharged
storage batteries; weak magnets in magneto, or defective
contacts at magneto; dirt in magneto distributor or poor
contact at collecting brushes. Dirty or cracked insulator

356 Aviation Engines

justed and the mixture delivered the cylinder burns prop-
erly, the exhaust gas will be clean and free from .the
objectionable odor present when gasoline is burned in
excess.

The character of combustion may be judged by the
color of the flame which issues from it when the engine
is running with an open throttle after nightfall. If the
flame is red, it indicates too much gasoline. If yellowish,
it shows an excess of air, while a properly proportioned
mixture will be evidenced by a pronounced blue flame,
such as given by a gas-stove burner.

The Duplex Model 0. D. Zenith carburetor used upon
most of the six- and eight-cylinder airplane engines con-
sists of a single float chamber, and a single air intake,
joined to two separate and distinct spray nozzles, venturi
and idling adjustments. It is to be noted that as the
carburetor barrels are arranged side by side, both valves
are mounted on the same shaft, and work in unison
through a single operating lever. It is not necessary to
alter their position. In order to make the engine idle
well, it is essential that the ignition, especially the spark-
plugs, should be in good condition. The gaskets between
carburetor and manifold, and between manifold and cylin-
ders should be absolutely air-tight. The adjustment for
low speed on the carburetor is made by turning in or out
the two knurled screws, placed one on each side of the
float chamber. After starting the engine and allowing it
to become thoroughly warmed, one side of the carburetor
should be adjusted so that the three cylinders it affects
fire properly at low speed. The other side should be
adjusted in the same manner until all six cylinders fire
perfectly at low speed. As the adjustment is changed
on the knurled screw a difference in the idling of the en-
gine should be noticed. If the engine begins to run evenly
or speeds up it shows that the mixture becomes right in
its proportion.

Be sure the butterfly throttle is closed as far as pos-
sible by screwing out the stop screw which regulates the

Zenith Carburetor Adjustments 357

closed position for Idling. Care should be taken to have
the butterfly held firmly against this stop screw at all
times while idling engine. If three cylinders seem to run
irregularly after changing the position of the butterfly,
still another adjustment may have to be made with the
knurled screw. Unscrewing this makes the mixture
leaner. Screwing in closes off some of the air supply to
the idling jet, making it richer. After one side has been
made to idle satisfactorily repeat the same procedure with
the opposite three cylinders. In other words, each side
should be idled independently to about the same speed.
Eemember that the main jet and compensating jet
have no appreciable effect on the idling of the engine.
The idling mixture is drawn directly through the opening
determined by the knurled screw and enters the car-
buretor barrel through the small hole at the edge of each
butterfly. This is called the priming hole and is only
effective during idling. Beyond that point the suction is
transferred to the main jet and compensator, which con-
trols the power of the engine beyond the idling position
of the throttle.

DEFECTS IN OILING SYSTEMS

While troubles existing in the ignition or carburetion
groups are usually denoted by imperfect operation of
the motor, such as lost power, and misfiring, derange-
ments of the lubrication or cooling systems are usually
evident by overheating, diminution in engine capacity, or
noisy operation. Overheating may be caused by poor
carburetion as much as by deficient cooling or insufficient
oiling. When the oiling group is not functioning as it
should the friction between the motor parts produces heat.
If the cooling system is in proper condition, as will be
evidenced by the condition of the water in the radiator,
and the carburetion group appears to be in good condi-
tion, the overheating is probably caused by some defect
in the oiling system.

The conditions that most commonly result in poor

358 Aviation Engines

lubrication are: Insufficient oil in the engine crank-case
or sump, broken or clogged oil pipes, screen at filter filled
with lint or dirt, broken oil pump, or defective oil-pump
drive. The supply of oil may be reduced by a defective
inlet or discharge-check valve at the mechanical oiler or
worn pumps. A clogged oil passage or pipe leading to
an important bearing point will cause trouble because
the oil cannot get between the working surfaces. It is
well to remember that much of the trouble caused by
defective oiling may be prevented by using only the best
grades of lubricant, and even if all parts of the oil sys-
tem are working properly, oils of poor quality will cause
friction and overheating.

DEFECTS IN COOLING SYSTEMS OUTLINED

Cooling systems are very simple and are not liable to
give trouble as a rule if the radiator is kept full of clean
water and the circulation is not impeded. When over-
heating is due to defective cooling the most common
troubles are those that impede water circulation. If the
radiator is clogged or the piping of water jackets filled
with rust or sediment the speed of water circulation will
be slow, which will also be the case if the water pump or
its driving means fail. Any scale or sediment in the water
jackets or in the piping or radiator passages will reduce
the heat conductivity of the metal exposed to the air, and
the water will not be cooled as quickly as though the scale
was not present.

TJie rubber hose often used in making the flexible
connections demanded between the radiator and water
manifolds of the engine may deteriorate inside and par-
ticles of rubber hang down that will reduce the area of
the passage. The grease from the grease cups mounted
on the pump- shaft bearing to lubricate that member often
finds its way into the waiter system and rots the inner
walls of the rubber hose, this resulting in strips of the
partly decomposed rubber lining hanging down and re-

Cooling System Faults 359

striding the passage. The cooling system is prone to
overheat after antifreezing solutions of which calcium
chloride forms a part have been used. This is due to
the formation of crystals of salt in the radiator passages
or water jackets, and these crystals can only be dissolved
by suitable chemical means, or removed by scraping when
the construction permits.

Overheating is often caused by some condition in the
fuel system that produces too rich or too lean mixture.
Excess gasoline may be supplied if any of the following
conditions are present: Bore of spray nozzle or stand-
pipe too large, auxiliary air- valve spring too tight, gaso-
line level too high, loose regulating valve, fuel-soaked
cork float, punctured sheet-metal float, dirt under float
control shut-off valve or insufficient air supply because
of a clogged air screen. If pressure feed is utilized there
may be too much pressure in the tank, or the float con-
trolled mechanism operating the shut-off in the float bowl
of the carburetor may not act quickly enough.

SOME CAUSES OF NOISY OPEKATION

There are a number of power-plant derangements
which give positive indication because of noisy operation.
Any knocking or rattling sounds are usually produced by
wear in connecting rods or main bearings of the engine,
though sometimes a sharp metallic knock, which is very
much the same as that produced by a loose bearing, is due
to carbon deposits in the cylinder heads, or premature
ignition due to advanced spark-time lever. Squeaking
sounds invariably indicate dry bearings, and whenever
such a sound is heard it should be immediately located
and oil applied to the parts thus denoting their dry con-
dition. Whistling or blowing sounds are produced by
leaks, either in the engine itself or in the gas manifolds.
A sharp whistle denotes the escape of gas under pressure
and is usually caused by a defective packing or gasket
that seals a portion of the combustion chamber or that is

360 Aviation Engines

used for a joint as the exhaust manifold. A blowing
sound indicates a leaky packing in crank-case. Grinding
noises in the motor are usually caused by the timing gears
and will obtain if these gears are dry or if they have be-
come worn. Whenever a loud knocking sound is heard
careful inspection should be made to locate the cause of
the trouble. Much harm may be done in a few minutes
if the engine is run with loose connecting rod or bearings
that would be prevented by taking up the wear or loose-
ness between the parts by some means of adjustment.

BRIEF SUMMARY OF HINTS FOR STARTING ENGINE

First make sure that all cylinders have compression.
To ascertain this, open pet cocks of all cylinders except
the one to be tested, crank over motor and see that a
strong opposition to cranking is met with once in tw r o
revolutions. If motor has no pet cocks, crank and notice
that oppositions are met at equal distances, two to every
revolution of the starting crank in a four-cylinder motor.
If compression is lacking, examine the parts of the cylin-
der or cylinders at fault in the following order, trying to
start the motor whenever any one fault is found and
remedied. See that the valve push rods or rocker arms
do not touch valve stems for more than approximately
y 2 revolution in every 2 revolutions, and that there is not
more than .010 to .020 inch clearance between them de-
pending on the make of the motor. Make sure that the
exhaust valve seats. To determine this examine the
spring and see that it is connected to the valve stem
properly. Take out valve and see that there is no ob-
struction, such as carbon, on its seat. See that valve
works freely in its guide. Examine inlet valve in same
manner. Listen for hissing sound while cranking motor
for leaks at other places.

Make sure that a spark occurs in each cylinder as
follows: If magneto or magneto and battery with non-
vibrating coil is used: Disconnect wire from spark-plug,

Summary of Hints for Starting Engine 361

hold end about % inch from cylinder or terminal of spark-
plug. Have motor cranked briskly and see if spark oc-
curs. Examine adjustment of interrupter points. See that
wires are placed correctly and not short circuited. Take
out spark-plug and lay it on the cylinder, being careful
that base of plug only touches the cylinder and that igni-
tion wire is connected. Have motor cranked briskly and
see if spark occurs. Check timing of magneto and see
that all brushes are making contact.

See if there is gasoline in the carburetor. See that
there is gasoline in the tank. Examine valve at tank.
Prime carburetor and see that spray nozzle passage is
clear. Be sure throttle is open. Prime cylinders by put-
ting about a teaspoonful of gasoline in through pet cock
or spark-plug opening. Adjust carburetor if necessary.

LOCATION OF ENGINE TROUBLES MADE EASY

The following tabulation has been prepared and origi-
nated by the writer to outline in a simple manner the
various troubles and derangements that interfere with
efficient internal-combustion engine action. The parts
and their functions are practically the same in all gas or
gasoline engines of the four-cycle type, and the general
instructions given apply just as well to all hydro-carbon
engines, even if the parts differ in form materially. The
essential components are clearly indicated in the many
part sectional drawings in this book so they may be
easily recognized. The various defects that may mate-
rialize are tabulated in a manner that makes for ready
reference, and the various defective conditions are found
opposite the part affected, and under a heading that de-
notes the main trouble to which the others are con-
tributing causes. The various symptoms denoting the
individual troubles outlined are given to facilitate their
recognition in a positive manner.

Brief note is also made of the remedies for the restora-
tion of the defective part or condition. It is apparent

362 Aviation Engines

that a table of this character is intended merely as a
guide, and it is a compilation of practically all the known
troubles that may materialize in gas-engine operation.
While most of the defects outlined are common enough
to warrant suspicion, they will never exist in an engine
all at the same time, and it will be necessary to make a
systematic search for such of those as exist.

To use the list advantageously, it is necessary to know
one main trouble easily recognized. For example, if the
power plant is noisy, look for the possible troubles under
the head of Noisy Operation; if it lacks capacity, the
derangement will undoubtedly be found under the head of
Lost Power. It is assumed in all cases that the trouble
exists in the power plant or its components, and not in
the auxiliary members of the ignition, carburetion, lubri-
cation, or cooling systems. The novice and student will
readily recognize the parts of the average aviation engine
by referring to the very complete and clearly lettered
illustrations of mechanism given in many parts of this
treatise.

Power and Overheating

363

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Aviation Engines

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Aviation Engines

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Ignition System Troubles 369

IGNITION SYSTEM TROUBLES ONLY
Motor Will Not Start or Starts Hard

Loose Battery Terminal.

Magneto Ground Wire Shorted.

Magneto Defective (No Spark at Plugs).

Broken Spark Plug Insulation.

Carbon Deposits or Oil Between Plug Points.

Spark-Plug Points Too Near Together or Far Apart.

Wrong Cables to Plugs.

Short Circuited Secondary Cable.

Broken Secondary Cable.

Dry Battery Weak.
Storage Battery Discharged.
Poor Contact at Timer.
Timer Points Dirty.

Battery Systems
Only. '

Poor Contact at Switch.

Primary Wires Broken, or Short Circuited. -~

Battery Grounded in Metal Container.

T3 j n -D i T ^ 01 1 Ignition

Battery Connectors Broken or Loose. ~ t n 1

Timer Points Out of Adjustment.
Defects in Induction Coil.

Ignition Timing Wrong, Spark Too Late or Too Early.

Defective Platinum Points in Breaker Box (Magneto).

Points Not Separating.

Broken Contact Maker Spring.

No Contact at Secondary Collector Brush.

Platinum Contact Points Burnt or Pitted.

Contact Breaker Bell Crank Stuck.

Fiber Bushing in Bell Crank Swollen.

Short Circuiting Spring Always in Contact.

Dirt or Water in Magneto Casing.

Oil in Contact Breaker.

Oil Soaked Brush and Collector Ring.

Distributor Filled with Carbon Particles.

370 Aviation Engines

Motor Stops Without Warning

Broken Magneto Carbon Brush.

Broken Lead Wire.

Broken Ground Wire.

Battery Ignition Systems.

Water on High Tension Magneto Terminal.

Main Secondary Cable Burnt Through by Hot Exhaust
Pipe (Transformer Coil, Magneto Systems).

Particle of Carbon Between Spark Plug Points.

Magneto Short Circuited by Ground Wire.

Magneto Out of Time, Due to Slipping Drive.

Water or Oil in Safety Spark Gap (Multi-cylinder Mag-
neto).

Magneto Contact Breaker or Timer Stuck in Eetard
Position.

Worn Fiber Block in Magneto Contact Breaker.

Binding Fiber Bushing in Contact Breaker Bell Crank.

Spark Advance Eod or Wire Broken.

Contact Breaker Parts Stuck.

Motor Runs Irregularly or Misfires

Loose Wiring or Terminals.

Broken Spark-Plug Insulator.

Spark-Plug Points Sooted or Oily.

Wrong Spark Gap at Plug Points.

Leaking Secondary Cable.

Prematurely Grounded Primary Wire.

Batteries Running Down (Battery Ignition only).

Poor Adjustment of Contact Points at Timer.

Wire Broken Inside of Insulation.

Loose Platinum Points in Magneto.

Weak Contact Spring.

Broken Collector Brush.

Dirt in Magneto Distributor Casing or Contact Breaker.

Worn Fiber Block or Cam Plate in Magneto.

Ignition System Troubles

371

"Worn Cam or Contact Eoll in Timer (Battery System

only).

Dirty Oil in Timer.
Sticking Coil Vibrators.
Coil Vibrator Points Pitted.
Oil Soaked Magneto Winding.
Punctured Magneto or Coil Winding.
Distributor Contact Segments Bough.
Sulphated Storage Battery Terminals.
Weak Magnets in Magneto.
Poor Contact at Magneto Contact Breaker Points.

DEFECTS IN ELECTRICAL SYSTEM COMPONENTS

To further simplify the location of electrical system
faults it is thought desirable to outline the defects that
can be present in the various parts of the individual de-
vices comprising the ignition system. If an airplane
engine is provided with magneto ignition solely, as most
engines are at the present time, no attention need be
paid to such items as storage or dry batteries, timer or
induction coil. There seems to be some development in
the direction of battery ignition so it has been considered
desirable to include components of these systems as well
as the almost universally used magneto group. . Spark-
plugs, wiring and switches are needed with either system.

DEFECT

Insulation cracked.
Insulation oil soaked.
Carbon deposits.
Insulator loose.
Gasket broken.
Electrode loose on shell.
Wire loose in insulator.
Air gap too close.
Air gap too wide.

Loose terminal.

Plug loose in cylinder.

Mica insulation oil soaked.

SPARK-PLUGS

TBOTJBLE CAUSED

Plug inoperative.
Cylinder misfires.
Short circuited spark.
Cylinder misfires.
Gas leaks by.
Cylinder misfires.
Cylinder misfires.
Short circuits spark.
Spark will not jump.

Cylinder may misfire.
. Gas leaks.
Short circuits spark.

EEMEDY

New insulation.

Clean.

Remove.

Tighten.

New gasket.

Tighten.

Set correctly.

Set points l/32'<

apart.
Tighten.
Tighten.
Replace.

372

Aviation Engines

MAGNETO

DEFECT

Dirty oil in distributor.
Metal dust in distributor.
Brushes not making contact.
Distributor segments worn.

Collecting brush broken.

Distributing brush broken.

Oil soaked winding.

Magnets loose on pole pieces.

Armature rubs.

Bearings worn.

Magnets weak.

Contact breaker points pitted.

Breaker points out of adjust-
ment

Defective winding (rare).

Punctured condenser (rare).

Driving gear loose.

Magneto armature out of time.

Magneto loose on base.

Contact breaker cam worn.

Fibre shoe or rolls worn
(Bosch).

Fibre bushing binding in con-
tact lever ( Bosch ) .

Contact lever return spring
broken.

Contact lever return spring
weak.

Ground wire grounded.

Ground wire broken.

Safety spark gap dirty.

Fused metal in spark gap.

Safety spark gap points too
close.

Loose distributor terminals.

Contact breaker sticks.

TROUBLE CAUSED

Engine misfires.
Engine misfires.
Current cannot pass.
Engine misfires.

Engine misfires.
Engine misfires.
Engine misfires.
Engine misfires.
Engine misfires.
Noisy.

Weak spark.
Engine misfires.
Engine misfires.

No spark.

Weak or no spark.

Noise.

Spark will not fire charge.

Misfiring and noisy.

Misfiring.

Misfiring.
No spark.
Misfiring.

No spark.

Engine will not stop.

.No spark.

No spark.

Misfiring.

No spark control.

Magneto switch short-circuited. No spark.
Magneto switch open circuit. No engine stop.

REMEDY

Clean.
Clean.

Strengthen spring.
Secure even bear-
ing.

New brush.
New brush.
Clean.

Tighten screws.
Repair bearings.
Replace.
Recharge.
Clean.
Reset.

Replace.
Replace.
Tighten.
Retime.
Tighten.
Replace.
Replace.

Ream slightly.

Replace.

Insulate.
Connect up.
Clean.
Remove.
Set properly.

Tighten.

Remove and clean

bearings.
Insulate.
Restore contact.

STORAGE BATTERY

DEFECT

Electrolyte low.

Loose terminals.
Sulphated terminals.

Battery discharged.
Electrolyte weak.

Plates sulphated.
Sediment or mud in bottom.
Active material loose in grids.

TROUBLE CAUSED

Weak current.

Misfiring.
Misfiring.

Misfiring or no spark.
Weak current.

Poor capacity.
Weak current.
Poor capacity.

REMEDY

Replenish with dis-
tilled water.

Tighten.

Clean thoroughly
and coat with
vaseline.

New charge.

Bring to proper
specific gravity.

Special slow charge.

Clean out.

New plates.

Ignition System Troubles

STORAGE BATTERY Continued

373

DEFECT

Moisture or acid on top of

cells.

Plugged vent cap.
Cracked vent cap.
Cracked cell jar.

TROUBLE CAUSED

Shorts terminals.

Buckles cell jars.
Acid spills out.
Electrolyte runs out.

REMEDY

Remove.

Make vent hole.
New cap.
New jar.

DRY CELL BATTERY

DETECT

Broken wires.

Loose terminals.

Weak cell (7 amperes or less)

Cells in contact.

Water in battery box.

TROUBLE CAUSED

No current.
Misfiring.
Misfiring.
Short circuit.

Short circuit.

REMEDY

New wires.
Tighten.
New cells.
Separate and insu-
late.
Dry out.

DEFECT

Contact segments worn or

pitted.
Platinum points pitted.

Dirty oil or metal dust in

interior.
Worn bearing.
Loose terminals.
Worn revolving contact brush.
Out of time.

TIMER

TROUBLE CAUSED

Misfiring.

REMEDY

Grind down smooth.

Misfiring.
Misfiring.

Smooth with oil
stone.
Clean out.

Misfiring.
Misfiring.
Misfiring.
Irregular spark.

Replace.
. Tighten.
Replace.
Reset.

DEFECT

Loose terminals.
Broken connections.
Vibrators out of adjustment.
Vibrator points pitted.
Defective condenser ")
Defective winding }
Poor contact at switch.
Broken internal wiring.
Poor coil unit.

INDUCTION COIL

TROUBLE CAUSED

Misfiring.
No spark.
Misfiring.
Misfiring.

No spark.

Misfiring.
No spark.
One cylinder affected.

REMEDY

Tighten.

Make new joints.

Readjust.

Clean.

Send to maker for

repairs.
Tighten.
Replace.
Replace.

DEFECT

Loose terminals anywhere.
Broken plug wire.
Broken timer wire.
Broken main battery wire.
Broken battery ground wire,
Broken magneto ground wire.
Chafed insulation anywhere. ")
Short circuit anywhere. j

WIRING

TROUBLE CAUSED REMEDY

Misfiring. Tighten.

One cylinder will not fire. Replace.

One coil will not buzz. Replace.

No spark. Replace.

Engine will not stop. Replace.

Misfiring. Insulate.

374 Aviation Engines

CARBURETTOR SYSTEM FAULTS SUMMARIZED

Motor Starts Hard or Will Not Start
No Gasoline in Tank.

No Gasoline in Carburetor Float Chamber.
Tank Shut-Off Closed.
Clogged Filter Screen.
Fuel Supply Pipe Clogged.
Gasoline Level Too Low.
Gasoline Level Too High (Flooding).
Bent or Stuck Float Lever.
Loose or Defective Inlet Manifold.
Not Enough Gasoline at Jet.
Cylinders Flooded with Gas.
Fuel Soaked Cork Float (Causes Flooding ).
Water in Carburetor Spray Nozzle.
Dirt in Float Chamber.
Gas Mixture Too Lean.
Carburetor Frozen (Winter Only).

Motor Stops In Flight

Gasoline Shut-Off Valve Jarred Closed.

Gasoline Supply Pipe Clogged.

No Gasoline in Tank.

Spray Nozzle Stopped Up.

Water in Spray Nozzle.

Particles of Carbon Between Spark-Plug Points.

Magneto Short Circuited by Ground in Wire.

Air Lock in Gasoline Pipe.

Broken Air Line or Leaky Tank (Pressure Feed System

Only).

Fuel Supply Pipe Partially Clogged.
Air Vent in Tank Filler Cap Stopped Up (Gravity and

Vacuum Feed System).
Float Needle Valve Stuck.
Water or Dirt in Spray Nozzle.
Mixture Adjusting Needle Jarred Loose (Eotary Motors

Only).

Carburetion System Faults 375

Motor Races, Will Not, Throttle Down

Air Leak in Inlet Piping.

Air Leak Through Inlet Valve Guides.

Control Eods Broken.

Defective Induction Pipe Joints.

Leaky Carburetor Flange Packing.

Throttle Not Closing.

Poor Slow Speed Adjustment (Zenith Carburetor).

Motor Misfires

Carburetor Float Chamber Getting Dry.

Water or Dirt in Gasoline.

Poor Gasoline Adjustment (Eotary Motors).

Not Enough Gasoline in Float Chamber.

Too Much Gasoline, Carburetor Flooding.

Incorrect Jet or Choke (Zenith Carburetor).

Broken Cylinder Head Packing Between Cylinders.

Noisy Operation

Popping or Blowing Back in Carburetor.

Incorrectly Timed Inlet Valves.

Inlet Valve Not Seating.

Defective Inlet Valve Spring.

Dirt Under Inlet Valve Seat.

Not Enough Gasoline (Open Needle Valve).

Muffler or Manifold Explosions.

Mixture Not Exploding Regularly.

Exhaust Valve Sticking.

Dirt Under Exhaust Valve Seat.

CHAPTEE XI

Tools for Adjusting and Erecting Forms of Wrenches Use and Care
of Files Split Pin Removal and Installation Complete Chisel
Set Drilling Machines Drills, Reamers, Taps and Dies Meas-
uring Tools Micrometer Calipers and Their Use Typical Tool
Outfits Special Hall-Scott Tools Overhauling Airplane Engines
Taking Engine Down Defects in Cylinders Carbon Deposits,
Cause and Prevention Use of Carbon Scrapers Burning Out
Carbon with Oxygen Repairing Scored Cylinders Valve Re-
moval and Inspection Reseating and Truing Valves Valve
Grinding Processes Depreciation in Valve Operating System
Piston Troubles Piston Ring Manipulation Fitting Piston Rings
Wrist-Pin Wear Inspection and Refitting; of Engine Bearings
Scraping Brasses to Fit Fitting Connecting Rods Testing for
Bearing Parallelism Cam-Shafts and Timing Gears Precautions
in Reassembling Parts.

TOOLS FOR ADJUSTING AND ERECTING

A very complete outfit of small tools, some of which
are furnished as part of the tool equipment of various
engines are shown in group at Fig. 163. This group in-
cludes all of the tools necessary to complete a very prac-
tical kit and it is not unusual for the mechanic who is
continually dismantling and erecting engines to possess
even a larger assortment than indicated. The small bench
vise provided is a useful auxiliary that can be clamped
to any convenient bench or table or even fuselage longeron
in an emergency and should have jaws at least three
inches wide and capable of opening four or five inches.
It is especially useful in that it will save trips to the
bench vises, as it has adequate capacity to handle practi-
cally any of the small parts that need to be worked on
when making repairs. A blow torch, tinner's snips and
soldering copper are very useful in sheet metal work and
in making any repairs requiring the use of solder. The
torch can be used in any operation requiring a source of

376

:*r ~ Small

Tinners

_^ Snips
Oil Can

Screw Drivers
(AH Me+al Type)

Vise

Machinists Hammer

SESJD (^^

Soldering Copper

c SideCuttinq Combination

Socket Wrench Set Parallel Jaw Plie

Adjustable End Wrench
Bicycle Wrench

Spark Plug
Small Socket Wrench Socket

Adjustable End Wrench
Spanner

Thin Wrench
Bearing Scraper

'Combination Pliers Cutting
Pliers

Cold Chisel

Center Punch

Carbon Scrapers

End Wrenches

Double End Wrenches

Fig. 163. Practical Hand Tools Useful in Dismantling and Repairing

Airplane Engines.

377

378 Aviation Engines

heat. The large box wrench shown under the vise is used
for removing large special- nuts and sometimes has one
end of the proper size to fit the valve chamber cap. The
piston ring removers are easily made from thin strips of
sheet metal securely brazed or soldered to a light wire
handle. These are used in sets of three for removing
and applying piston rings in a manner to be indicated.
The uses of the wrenches, screw drivers, and pliers shown
are known to all and the variety outlined should be suffi-
cient for all ordinary work of restoration. The wrench
equipment is very complete, including a set of open end
S-wrenches to fit all standard bolts, a spanner wrench,
socket or box wrenches for bolts that are inaccessible with
the ordinary type, adjustable end wrenches, a thin monkey
wrench of medium size, a bicycle wrench for handling
small nuts and bolts, a Stillson wrench for pipe and a
large adjustable monkey wrench for the stubborn fasten-
ings of large size.

Four different types of pliers are shown, one being a
parallel jaw type with size cutting attachment, while the
other illustrated near it is a combination parallel jaw type
adapted for use on round work as well as in handling
flat stock. The most popular form of pliers is the com-
bination pattern shown beneath the socket wrench set.
This is made of substantial drop forgings having a hinged
joint that can be set so that a very wide opening at the
jaws is possible. These can be used on round work and
for wire cutting as well as for handling flat work. Eound
nose pliers are very useful also.

A very complete set of files, including square, half
round, mill, flat bastard, three-cornered and rat tail are
also necessary. A hacksaw- frame and a number of saws,
some with fine teeth for tubing and others with coarser
teeth for bar or solid stock will be found almost indis-
pensable. A complete punch and chisel set should be pro-
vided, samples of which are shown in the group while the
complete outfit is outlined in another illustration. A
number of different forms and sizes of chisels are neces-

Forms of Wrenches 379

sary, as one type is not suitable for all classes -of work.
The adjustable end wrenches can be used in many places
where a monkey wrench cannot be fitted and where it
will be difficult to use a wrench having a fixed opening.
The Stillson pipe wrench is useful in turning studs, round
rods, and pipes that cannot be turned by any other means.
A complete shop kit must necessarily include various sizes
for Stillson and monkey wrenches, as no one size can be
expected to handle the wide range of work the engine
repairman must cope with. Three sizes of each form of
wrench can be used, one, a 6 inch, is as small as is needed
while a 12 inch tool will handle almost any piece of pipe
or nut used in engine construction.

Three or four sizes of hammers should be provided,
according to individual requirement, these being small
riveting, medium and heavyweight machinist's hammers.
A very practical tool of this nature for the repair shop
can be used as a hammer, screw driver or pry iron. It is
known as the " Spartan" hammer and is a tool steel drop
forging in one piece having the working surfaces properly
hardened and tempered while the metal is distributed so
as to give a good balance to the head and a comfortable
grip to the handle. The hammer head provides a posi-
tive and comfortable T-handle when the tool is used as
a screw driver or " tommy" bar. Machinist's hammers
are provided with three types of heads, these being of
various weights. The form most commonly used is
termed the "ball pein" on account of the shape of the
portion used for riveting. The straight pein is just the
same as the cross pein, except that in the latter the
straight portion is at right angles to the hammer handle,
while in the former it is parallel to that member.

FORMS OF WRENCHES

Wrenches have been made in infinite variety and there
are a score or more patterns of different types of ad-
justable socket and off-set wrenches. The various wrench

380

Aviation Engines

types that differ from the more conventional monkey
wrenches or those of the Stillson pattern are shown at
Fig. 164. The " perfect handle" is a drop forged open
end form provided with a wooden handle similar to that
used on a monkey wrench in order to provide a better
grip for the hand. The " Saxon" wrench is a double
alligator form, so called because the jaws are in the form
of a V-groove having one side of the V plain, while the
other is serrated in order to secure a tight grip on round
objects. In the form shown, two jaws of varying sizes

5TARRETT

MILLER

Fig. 164. Wrenches are Offered in Many Forms.

are provided, one for large work, the other to handle the
smaller rods. One of the novel features in connection
with this wrench is the provision of a triple die block in
the centre of the handle which is provided with three
most commonly used of the standard threads including
% 6 -inch-18, %-inch-16, and %-inch-13. This is useful in
cleaning up burred threads on bolts before they are
replaced, as burring is unavoidable if it has been neces-
sary to drive them out with a hammer. The "Lakeside"
wrench has an adjustable pawl engaging with one of a
series of notches by which the opening may be held in
any desired position.

Ever since the socket wrench was invented it has been

Forms of Wrenches 381

a popular form because it can be used in many places
where the ordinary open end or monkey wrench cannot
be applied owing to lack of room for the head of the
wrench. A typical set which has been made to fit in a very
small space is shown at D. It consists of a handle, which
is nickel-plated and highly polished, a long extension bar,
a universal joint and a number of case hardened cold
drawn steel sockets to fit all commonly used standard nuts
and bolt heads. Two screw-driver bits, one small and the
other large to fit the handle, and a long socket to fit spark-
plugs are also included in this outfit. The universal joint
permits one to remove nuts in a position that would be
inaccessible to any other form of wrench, as it enables
the socket to be turned even if the handle is at one side
of an intervening obstruction.

The " Pick-up " wrench, shown at E, is used for spark-
plugs and the upper end of the socket is provided with a
series of grooves into which a suitable blade carried by
the handle can be dropped. The handle is pivoted to the
top of the socket in such a way that the blades may be
picked up out of the grooves by lifting on the end of the
handle and dropped in again when the handle is swung
around to the proper point to get another hold on the
socket. The "Miller" wrench shown at F, is a combina-
tion socket and open end type, made especially for use
with spark-plugs. Both the open end 'and the socket are
convenient. The "Handy" set shown at G, consists of a
number of thin stamped wrenches of steel held together
in a group by a simple clamp fitting, which enables either
end of any one of the four double wrenches to be brought
into play according to the size of the nut to be turned.
The "Cronk" wrench shown at H, is a simple stamping
having an alligator opening at one end and a stepped
opening capable of handling four different sizes of stand-
ard nuts or bolt heads at the other. Such wrenches are
very cheap and are worth many times their small cost,
especially for fitting nuts where there is not sufficient
room to admit the more conventional pattern. The

382 Aviation Engines

"Starrett" wrench set, which is shown at I, consists of
a ratchet handle together with an extension bar and uni-
versal joint, a spark-plug socket, a drilling attachment
which takes standard square shank drills from %-inch to
3/2-inch in diameter, a double ended screw-driver bit and
several adjustments to go with the drilling attachment.
Twenty-eight assorted cold drawn steel sockets similar in
design to those shown at D, to fit all standard sizes of
square and hexagonal headed nuts are also included. The
reversible ratchet handle, which may be slipped over the
extension bar or the universal joint and which is also
adapted to take the squared end of any one of the sockets
is exceptionally useful in permitting, as it does, the in-
stant release of pressure when it is desired to swing the
handle back to get another hold on the nut. The socket
wrench sets are usually supplied in hard wood cases or
in leather bags so that they may be kept together and
protected against loss or damage. With a properly se-
lected socket wrench set, either of the ratchet handle or
T-handle form, any nut on the engine may be reached and
end wrenches will not be necessary.

USE AND CARE OF FILES

Mention has been previously made of the importance
of providing a complete set of files and suitable handles.
These should be in various grades or degrees of fineness
and three of each kind should be provided. In the flat
and half round files three grades are necessary, one with
coarse teeth for roughing, and others with medium and
fine teeth for the finishing cuts. The round or rat tail
file is necessary in filing out small holes, the half round
for finishing the interior of large ones. Half round files
are also well adapted for finishing surfaces of peculiar
contour, such as the inside of bearing boxes, connecting
rod and main bearing caps, etc. Square files are useful
in finishing keyways or cleaning out burred splines, while
the triangular section or three-cornered file is of value in

Use and Care of Files

383

cleaning out burred threads and sharp corners. Flat files
are used on all plane surfaces.

The file brush shown at Fig. 165, A, consists of a large
number of wire bristles attached to a substantial wood

Fig. 165. Illustrating Use and Care of Files.

back having a handle of convenient form so that the
bristles may be drawn through the interstices between
the teeth of the file to remove dirt and grease. If the

384 Aviation Engines

teeth are filled with pieces of soft metal, such as solder
or babbitt, it may be necessary to remove this accumula-
tion with a piece of sheet metal as indicated at Fig.
165, B. The method of holding a file for working on
plain surfaces when it is fitted with the regular form of
wooden handle is shown at C, while two types of handles
enabling the mechanic to use the flat file on plain sur-
faces of such size that the handle type indicated at C,
could not be used on account of interfering with the sur-
face finished are shown at D. The method of using a
file when surfaces are finished by draw filing is shown at
E. This differs from the usual method of filing and is
only used when surfaces are to be polished and very little
metal removed.

SPLIT PIN REMOVAL AND INSERTION

One of the most widely used of the locking means to
prevent nuts or bolts from becoming loose is the simple
split pin, sometimes called a "cotter pin." These can be
handled very easily if the special pliers shown at Fig.
166, A, are used. They have a curved jaw that, permits
of grasping the pin firmly and inserting it in the hole
ready to receive it. It is not easy to insert these split
pins by other means because the ends are usually spread
out and it is hard to enter the pin in the hole. With the
cotter pin pliers the ends may be brought close together
and as the plier jaws are small the pin may be easily
pushed in place. Another use of this plier, also indicated,
is to bend over the ends of the split pin in order to pre-
vent it from fal-ling out. To remove these pins a simple
curved lever, as shown at Fig. 166, B, is used. This has
one end tapering to a point and is intended to be in-
serted in the eye of the cotter pin, the purchase offered
by the handle permitting of ready removal of the pin
after the ends have been closed by the cotter pin pliers.

Miscellaneous Small Tools

385

COMPLETE CHISEL SET

A complete chisel set suitable for repair shop use is
also shown at Fig. 166. The type at C is known as a
"cape"- chisel and has a narrow cutting point and is in-
tended to chip keyways, remove metal out of corners and
for all other work where the broad cutting edge chisel,

Tig. 166. Outlining Use of Cotter Pin Pliers, Spring Winder, and Showing
Practical Outfit of Chisels.

shown at D, cannot be used. The form with the wide
cutting edge is used in chipping, cutting sheet metal, etc.
At E, a round nose chisel used in making oil ways is out-
lined, while a similar tool having a pointed cutting edge
and often used for the same purpose is shown at F. The
centre punch depicted at G, is very useful for marking
parts either for identification or for drilling. In addition

386 Aviation Engines

to the chisels shown, a number of solid punches or drifts
resembling very much that shown at E, except that the
point is blunt should be provided to drive out taper pins,
bolts, rivets, and other fastenings of this nature. These
should be provided in the common sizes. A complete set
of real value would start at %-inch and increase by incre-
ments of %2-inch up to %-inch. A simple spring winder
is shown at Fig. 166, H, this making it possible for the
repairman to wind coil springs, either on the lathe or in
the vise. It will handle a number of different sizes of
wire and can be set to space the coils as desired.

DRILLING MACHINES

Drilling machines may be of two kinds, hand or power
operated. For drilling small holes in metal it is neces-
sary to run the drill fast, therefore the drill chuck is
usually driven by gearing in order to produce high drill
speed without turning the handle too fast. A small hand
drill is shown at Fig. 167, A. As will be observed, the
chuck spindle is driven by a small bevel pinion, which in
turn, is operated by a large bevel gear turned by a crank.
The gear ratio is such that one turn of the handle will
turn the chuck five or six revolutions. A drill of this
design is not suited for drills any larger than one-quarter
inch. For use with drills ranging from one-eighth to
three-eighths, or even half -inch the hand drill presses
shown at C and D are used. These have a pad at the
upper end by which pressure may be exerted with the
chest in order to feed the drill into the work, and for
this reason they are termed "breast drills." The form
at C has compound gearing, the drill chuck being driven
by the usual form of bevel pinion in mesh with a larger
bevel gear at one end of a countershaft. A small helical
spur pinion at the other end of this countershaft receives
its motion from a larger gear turned by the hand crank.
This arrangement of gearing permits of high spindle
speed without the use of large gears, as would be neces-

Drilling Machines

387

sary if but two were used. The form at D gives two
speeds, one for use with small drills is obtained by en-
gaging the lower bevel pinion with the chuck spindle and

CHUCK

Fig. 167. Forms of Hand Operated DriUing Machines.

driving it by the large ring gear. The slow speed is ob-
tained by shifting the clutch so that the top bevel pinion
drives the drill chuck. As this meshes with a gear but
slightly larger in diameter, a slow speed of the drill
chuck is possible. Breast drills are provided with a

388 Aviation Engines

handle screwed into the side of the frame, these are used
to steady the drill press. For drilling extremely large
holes which are beyond the capacity of the usual form
of drill press the ratchet form shown at B, may be used
or the bit brace outlined at E. The drills used with either
of these have square shanks, whereas those used in the
drill presses have round shanks. The bit brace is also
used widely in wood work and the form shown is provided
with a ratchet by which the bit chuck may be turned
through only a portion of a revolution in either direction
if desired.

DRILLS, REAMERS, TAPS AND DIES

In addition to the larger machine tools and the simple
hand tools previously described, an essential item of equip-
ment of any engine or plane repair shop, even in cases
where the ordinary machine tools are not provided, is a
complete outfit of drills, reamers, and threading tools.
Drills are of .two general classes, the flat and the twist
drills. The flat drill has an angle between cutting edges
of about 110 degrees and is usually made from special
steel commercially known as drill rod.

A flat drill cannot be fed into the work very fast be-
cause it removes metal by a scraping, rather than a
cutting process. The twist drill in its simplest form is
cylindrical throughout the entire length and has spiral
flutes which are ground off at the end to form the cutting
lip and which also serve to carry the metal chips out of
the holes. The simplest form of twist drill used is shown
at Fig. 168, C, and is known as a " chuck" drill, because
it must be placed in a suitable chuck to turn it. A twist
drill removes metal by cutting and it is not necessary to
use a heavy feed as the drill will tend to feed itself into
the work.

Larger drills than %-inch are usually made with a
tapered shank as shown at Fig. 168, B. At the end of
the taper a tongue is formed which engages with a suit-
able opening in the collet, as the piece used to support

Drills and Reamers

389

the drill is called. The object of this tongue is to relieve
the tapered portion of the drill from the stress of driving
by frictional contact alone, as this would not turn the
drill positively and the resulting slippage would wear the
socket, .this depreciation changing the taper and making
it unfit for other drills. The tongue is usually propor-
tioned so it is adequate to drive the drill under any con-

Fig. 168. Forms of Drills Used in Hand and Power Drilling Machines.

dition. A small keyway is provided in the collet into which
a tapering key of flat stock may be driven against the
end of the tongue to drive the drill from the spindle. A
standard taper for drill shanks generally accepted by the
machine trade is known as the Morse and is a taper of
five-eighths of an inch to the foot. The Brown and Sharp
form tapers six-tenths of an inch to the foot. Care must
be taken, therefore, when purchasing drills and collets,

390 Aviation Engines

to make sure that the tapers coincide, as no attempt
should be made to run a Morse taper in a Brown and
Sharp collet, or vice versa.

Sometimes cylindrical drills have straight flutes, as
outlined at Fig. 168, A. Such drills are used with soft
metals and are of value when the drill is to pass entirely
through the work. The trouble with a drill with spiral
flutes is that it will tend to draw itself through as the
cutting lips break through. This catching of the drill
may break it or move the work from its position. With
a straight flute drill the cutting action is practically the
same as with the flat drill shown at Fig. 168, E and F.

If a drill is employed in boring holes through close-
grained, tough metals, as wrought or malleable iron and
steel, the operation will be facilitated by lubricating the
drill with plenty of lard oil or a solution of soda and
water. . Either of these materials will effectually remove
the heat caused by the friction of the metal removed
against the lips of the drill, and the danger of heating
the drill to a temperature that will soften it by drawing
the temper is minimized. In drilling large or deep holes
it is good practice to apply the lubricating medium di-
rectly at the drill point. Special drills of the form shown
at Fig. 62, D, having a spiral oil tube running in a
suitably formed channel, provides communication between
the point of the drill and a suitable receiving hole on a
drilled shank. The oil is supplied by a pump and its
pressure not only promotes positive circulation and re-
moval of heat, but also assists in keeping the hole free
of chips. In drilling steel or wrought iron, lard oil
applied to the point of the drill will facilitate the drill-
ing, but this material should never be used with either
brass or cast iron.

The sizes to be provided depend upon the nature of
the work and the amount of money that can be invested
in drills. It is common practice to provide a set of drills,
such as shown at Fig. 169, which are carried in a suitable
metal stand, these being known as number drills on ac-

Drills and Reamers

391

count of conforming to the wire gauge standards. Num-
ber drills do not usually run higher than % 6 inch in
diameter. Beyond this point drills are usually sold by
the diameter. A set of chuck drills, ranging from % to
% inch, advancing by %2 inch, and a set of Morse taper
shank drills ranging from % to l 1 ^ inches, by increments
of Vis inch, will be all that is needed for the most pre-
tentious repair shop, as it is cheaper to bore holes larger
than 1% inches with a boring tool than it is to carry a

Fig. 169. Useful Set of Number Drills, Showing Stand for Keeping These
in an Orderly Manner.

number of large drills in stock that would be used very
seldom, perhaps not enough to justify their cost.

In grinding drills, care must be taken to have the
lips of the same length, so that they will form the same
angle with the axis. If one lip is longer than the other,
as shown in the flat drill at Fig. 168, E, the hole will be
larger than the drill size, and all the work of cutting will
come upon, the longest lip. The drill ends should be sym-
metrical, as shown at Fig. 168, F.

It is considered very difficult to drill a hole to an exact
diameter, but for the most work a variation of a few
thousandths of an inch is of no great moment. Where
accuracy is necessary, holes must be reamed out to the
required size. In reaming, a hole is drilled about %2 inch

392

Aviation Engines

smaller than is required, and is enlarged with a cutting
tool known as the reamer. Eeamers are usually of the
fluted form shown at Fig. 170, A. Tools of this nature
are not designed to remove considerable amounts of
metal, but are intended to augment the diameter of the
drill hole by only a small fraction of an inch. Eeamers

1 C

Fig. 170. Illustrating Standard Forms of Hand and Machine Eeamers.

are tapered slightly at the point in order that they will
enter the hole easily, but the greater portion of the fluted
part is straight, all cutting edges being parallel. Hand
reamers are made in either the straight or taper forms,
that at A, Fig. 170, being straight, while B has tapering
flutes. They are intended to be turned by a wrench simi-
lar to that employed in turning a tap, as shown at Fig.

Types of Reamers and Use 393

172, C. The reamer shown at Fig. 170, C, is a hand
reamer. The form at D has spiral flutes similar to a
twist drill, and as it is provided with a taper shank it is
intended to be turned by power through the medium of
a suitable collet.

As the solid reamers must become reduced in size
when sharpened, various forms of inserted blade reamers
have been designed. One of these is shown at E, and as
the cutting surfaces become reduced in diameter it is
possible to replace the worn blades with others of proper
size. Expanding reamers are of the form shown at F.
These have a bolt passing through that fits into a taper-
ing hole in the interior of the split reamer portion of the
tool. If the hole is to be enlarged a few thousandths of
an inch, it is possible to draw up on the nut just above
the squared end .of the shank, and by drawing the taper-
ing wedge farther into the reamer body, the cutting por-
tion will be expanded and will cut a larger hole.

Eeamers must be very carefully sharpened or there
will be a tendency toward chattering with a consequent
production of a rough surface. There are several methods
of preventing this chattering, one being to separate the
cutting edges by irregular spaces, w r hile the most common
method, and that to be preferred on machine reamers, is
to use spiral flutes, as shown at Fig. 170, D. Special
taper reamers are made to conform to the various taper
pin sizes which are sometimes used in holding parts to-
gether in an engine. A taper of %e inch per foot is in-
tended for holes where a pin, once driven in, is to remain
in place. "When "it is desired that the pin be driven out,
the taper is made steeper, generally 14 i nc ^ P er foot,
which is the standard taper used on taper pins.

When threads are to be cut in a small hole, it will be
apparent that it will be difficult to perform this operation
economically on a lathe, therefore when internal thread-
ing is called for, a simple device known as a "tap" is
used. There are many styles of taps, all conforming to
different standards. Some are for metric or foreign

394

Aviation Engines

threads, some conform to the American standards, while
others are nsed for pipe and tubing. Hand taps are the
form most used in repair shops, these being outlined at
Fig. 171, A and B. They are usually sold in sets of three,
known respectively as taper, plug, and bottoming. The
taper tap is the one first put into the hole, and is then
followed by the plug tap which cuts the threads deeper.

Fig. 171. Tools for Thread Cutting.

If it is imperative that the thread should be full size
clear to the bottom of the hole, the third tap of the set,
which is straight-sided, is used. It would be difficult to
start a bottoming tap into a hole because it would be
larger in diameter at its point than the hole. The taper
tap, as shown at A, Fig. 171, has a portion of the cutting
lands ground away at the point in order that it will enter
the hole. The manipulation of a tap is not hard, as it
does not need to be forced into the work, as the thread

Use of Taps and Dies 395

will draw it into the hole as the tap is turned. The
tapering of a tap is done so that no one thread is called
upon to remove all of the metal, as for about half way up
the length of the tap each succeeding thread is cut a
little larger by the cutting edge until the full thread
enters the hole. Care must be taken to always enter a
tap straight in order to have the thread at correct angles
to the surface.

In cutting external threads on small rods or on small
pieces, such as bolts and studs, it is not always economi-
cal to do this work in the lathe, especially in repair work.
Dies are used to cut threads on pieces that are to be
placed in tapped holes that have been threaded by the
corresponding size of tap. Dies for small work are often
made solid, as shown at Fig. 171, C, but solid dies are
usually limited to sizes below y 2 inch. Sometimes the
solid die is cylindrical in shape, with a slot through
one side which enables one to obtain a slight degree of
adjustment by squeezing the slotted portion together.
Large dies, or the sizes over y 2 inch, are usually made
in two piece's in order that the halves may be closed up
or brought nearer together. The advantage of this form
of die is that either of the two pieces may be easily sharp-
ened, and as it may be adjusted very easily the thread
may be cut by easy stages. For example, the die may be
adjusted to cut large, which will produce a shallow thread
that will act as an accurate guide when the die is closed
up and a deeper thread cut.

A common form of die holder for an adjustable die is
shown at Fig. 172, A. As will be apparent, it consists
pf a central body portion having guide members to keep
the die pieces from falling out and levers at each end in
order to permit the operator to exert sufficient force to
remove the metal. The method of adjusting the depth of
thread with a clamp screw when a two-piece die is em-
ployed is also clearly outlined. The die stock shown at
B is used for the smaller dies of the one-piece pattern,
having a slot in order that they may be closed up slightly

396

Aviation Engines

by the clamp screw. The reverse side of the diestock
shown at B is outlined below it, and the guide pieces,
which may be easily moved in or out, according to the
size of the piece to be threaded by means of eccentrically
disposed semi-circular slots in the adjustment plate, are

Fig. 172. Showing Holder Designs for One- and Two-Piece Thread Cutting

Dies.

shown. These movable guide members have small pins
let into their surface ^hich engage the slots, and they
may be moved in or out, as desired, according to the posi-
tion of the adjusting plate. The use of the guide pieces
makes for accurate positioning or centering of the rod to
be threaded. Dies are usually sold in sets, and are com-
monly furnished as a portion of a complete outfit such as

Measuring Tools

397

outlined at Fig. 173. That shown has two sizes of die-
stock, a tap wrench, eight assorted dies, eight assorted
taps, and a small screw driver for adjusting the die. An
automobile repair shop should be provided with three
different sets of taps and dies, as three different stand-
ards for the bolts and nuts are used in fastening auto-
mobile components. These are the American, metric

Fig. 173. Useful Outfit of Taps and Dies for the Engine Repair Shop.

(used on foreign engines), and the S. A. E. standard
threads. A set of pipe dies and taps will also be found
useful.

MEASURING TOOLS

The tool outfit of the machinist or the mechanic who
aspires to do machine work must include a number of
measuring tools which are not needed by the floor man or
one who merely assembles and takes apart the finished
pieces. The machinist who must convert raw material
into finished products requires a number of measuring
tools, some of which are used for taking only approxi-
mate measurements, such as calipers and scales, while
others are intended to take very accurate measurements,
such as the Vernier and the micrometer. A number of
common forms of calipers are shown at Fig. 174. These
are known as inside or outside calipers, depending upon
the measurements they are intended to take. That at A

398

Aviation Engines

is an inside caliper, consisting of two legs, A and D, and
a gauging piece, B, which can be locked to leg A, or re-
leased from that member by the screw, C. The object of
this construction is to permit of measurements being
taken at the bottom of a. two diameter hole, where the
point to be measured is of larger diameter than the por-
tion of the hole through which the calipers entered. It
will be apparent that the legs A and D must be brought
close together to pass through the smaller holes. This

Fig. 174. Common Forms of Inside and Outside Calipers.

may be done without losing the setting, as the guide bar
B will remain in one position as determined by the size
of the hole to be measured, while the leg A may be swung
in to clear the obstruction as the calipers are lifted out.
When it is desired to ascertain the measurements the leg
A is pushed back into place into the slotted portion of the
guide B, and locked by the clamp screw C. A tool of this
form is known as an internal transfer caliper.

The form of caliper shown at B is an outside caliper.
Those at C and D are special forms for inside and out-

Measuring Tools 399

side work, the former being used, if desired, as a divider,
while the latter may be employed for measuring the
walls of tubing. The calipers at E are simple forms,
having a friction joint to distinguish them from the spring
calipers shown at B, C and D. In order to permit of
ready adjustment of a spring caliper, a split nut as shown
at G is sometimes used. A solid nut caliper can only be
adjusted by screwing the nut in or out on the screw,
which may be a tedious process if the caliper is to be set
from one extreme to the other several times in succession.
With a slip nut as shown at Gr it is possible to slip it
from one end of the thread to the other without turning
it, and of locking it in place at any desired point by
simply allowing the caliper leg to come in contact with
it. The method of adjusting a spring caliper is shown
at Fig. 174, H.

Among the most common of the machinist's tools are
those used for linear measurements. The usual forms are
shown in group, Fig. 175. The most common tool, which
is widely known, is the carpenter's folding two-foot rule
or the yardstick. While these are very convenient for
taking measurements where great accuracy is not re-
quired, the machinist must work much more accurately
than the carpenter, and the standard steel scale which is
shown at D, is a popular tool for the machinist. The
steel scale is in reality a graduated straight edge and
forms an important part of various measuring tools.
These are made of high grade steel and vary from 1 to
48 inches in length. They are carefully hardened in order
to preserve the graduations, and all surfaces and edges
are accurately ground to insure absolute parallelism. The
graduations on the high grade scales are produced with
a special device known as a dividing engine, but on
cheaper scales, etching suffices to provide a fairly accurate
graduation. The steel scales may be very thin and flex-
ible, or may be about an eighth of an inch thick on the
twelve-inch size, which is that commonly used with com-
bination squares, protractors and other tools of that,

400

Aviation Engines

nature. The repairrnan's scale should be graduated both
with the English system, in which the inches are di-
vided into eighths, sixteenths, thirty-secondths and sixty-

1 2 3 4. 5.

il.i.l.i.lii.l.i.lililililiiiliiil.iif.i.l.i.

rij il i

91 ' 3

i h I ill

i h

Fig. 175. Measuring Appliances for the Machinist and Floor Man.

fourths, and also in the metric system, divided into milli-
meters and centimeters. Some machinists use scales
graduated in tenths, twentieths, fiftieths and hundredths.

Measuring Instruments 401

This is not as good a system of graduation as the more
conventional one first described.

Some steel scales are provided with a slot or groove
cut the entire length on one side and about the center of
the scales. This permits the attachment of various fit-
tings such as the protractor head, which enables the ma-
chinist to measure angles, or in addition the heads convert
the scale into a square or a tool permitting the accurate
bisecting of pieces of circular section. Two scales are
sometimes joined together to form a right angle, such as
shown at Fig. 175, C. This is known as a square and is
very valuable in ascertaining the truth of vertical pieces
that are supposed to form a right angle with a base piece.

The Vernier is a device for reading finer divisions on
a scale than those into which the scale is divided. Sixty-
fourths of an inch are about the finest division that can
be read accurately with the naked eye. When fine work
is necessary a Vernier is employed. This consists essen-
tially of two rules so graduated that the true scale has
each inch divided into ten equal parts, the upper or Ver-
nier portion has ten divisions occupying the same space
as nine of the divisions of the true scale. It is evident,
therefore, that one of the divisions of the Vernier is equal
to nine-tenths of one of those on the true scale. If the
Vernier scale is moved to the right so that the gradua-
tions marked ' * 1 ' ' shall "coincide, it will have moved one-
tenth of a division on the scale or one-hundredth of an
inch. When the graduations numbered 5 coincide the
Vernier will have moved five-hundredths of an inch ; when
the lines marked and 10 coincide, the Vernier will have
moved nine-hundredths of an inch, and when 10 on the
Vernier comes opposite 10 on the scales, the upper rule
will have moved ten-hundredths of an inch, or the whole
of one division on the scale. By this means the scale,
though it may be graduated only to tenths of an inch,
may be accurately set at points with positions expressed
in hundredths of an inch. When graduated to read in
thousandths, the true scale is divided into fifty parts and

402

Aviation Engines

the Vernier into twenty parts. Each division of the Ver-
nier is therefore equal to nineteen-twentieths of one of
the true scale. If the Vernier be moved so the lines of
the first division coincide, it will have moved one-twen-
tieth of one-fiftieth, or .001 inch. The Vernier principle
can be readily grasped by studying the section of the
Vernier scale and true scale shown at Fig. 176, A.

The caliper scale which is shown at Fig. 175, A, per-
mits of taking the over-all dimension of any parts that

5lN.

Fig. 176. At Left, Special Form of Vernier Calipeff for Measuring Gea*
Teeth; at Right, Micrometer for Accurate Internal Measurements.

will go between the jaws. This scale can be adjusted very
accurately by means of a fine thread screw attached to a
movable jaw and the divisions may be divided by eye
into two parts if one sixty-fourth is the smallest of the
divisions. A line is indicated on the movable jaw and
coincides with the graduations on the scale. As will be
apparent, if the line does not coincide exactly with one
of the graduations it will be at some point between the
lines and the true measurement may be approximated with-
out trouble.

A group of various other measuring tools of value to
the machinist is shown at Fig; 177. The small scale at A
is termed a "center gauge," because it can be used to test

Measuring Tools

403

the truth of the taper of either a male or female lathe
center. The two smaller nicks, or v's, indicate the shape
of a standard thread, and may be used as a guide for
grinding the point of a thread-cutting tool. The cross
level which is show y n at B is of marked utility in erecting,
as it will indicate absolutely if the piece it is used to test

Fig. 177. Measuring Appliances of Value in Airplane Repair Work.

is level. It will indicate if the piece is level ' along its
width as well as its length.

A very simple attachment for use with a scale that
enables the machinist to scribe lines along the length of
a cylindrical piece is shown at Fig. 177, C. These are
merely small wedge-shaped clamps having an angular
face to rest upon the bars. The thread pitch gauge which
is shown at Fig. 177, D, is an excellent pocket tool for the
mechanic, as it is often necessary to determine without
loss of time the pitch of the thread on a bolt or in a nut.
This consists of a number of leaves having serrations on
one edge corresponding to the standard thread it is to be

404 Aviation Engines

used in measuring. The tool shown gives all pitches up
to 48 threads per inch. The leaves may be folded in out
of the way when not in use, and their shape admits of
their being used in any position without the remainder
of the set interfering with the one in use. The fine pitch
gauges have. slim, tapering leaves of the correct shape to
be used in finding the pitch of small nuts. As the tool is
round when the leaves are folded back out of the way, it
is an excellent pocket tool, as there are no sharp corners
to wear out the pocket. Practical application of a Ver-
nier having measuring heads of special form for measur-
ing gear teeth is shown at Fig. 176, A. As the action of
this tool has been previously explained, it will not be
necessary to describe it further.

MICROMETER CALIPERS AND THEIR USE

Where great accuracy is necessary in taking measure-
ments the micrometer caliper, which in the simple form
will measure easily .001 inch (one-thousandth part of an
inch) and when fitted with a Vernier that will measure
.0001 inch (one ten- thousandth part of an inch), is used.
The micrometer may be of the caliper form for measur-
ing outside diameters or it may be of the form shown at
Fig. 176, B, for measuring internal diameters. The opera-
tion of both forms is identical except that the internal
micrometer is placed inside of the bore to be measured
while the external form is used just the same as a caliper.
The form outlined will measure from one and one-half to
six and a half inches as extension points are provided to
increase the range of the instrument. The screw has a
movement of one-half inch and a hardened anvil is placed
in the end of the thimble in order to prevent undue wear
at that point. The extension points or rods are accurately
made in standard lengths and are screwed into the body
of the instrument instead of being pushed in, this insur-
ing firmness and accuracy. Two forms of micrometers
for external measurements are shown at Fig. 178. The

Micrometers and Their Use

405

top one is graduated to read in thousandths of an inch,
while the lower one is graduated to indicate hundredths
of a millimeter. The mechanical principle involved in the
construction of a micrometer is that of a screw free to

Oevefojxntrit of
Sco/e on Qoml
of Inch Micrometer

fin

<Scof6 on Borre/
of Afefa'c Micrometer

Tig. 178. Standard Forms of Micrometer Caliper for External Measure-
ments.

move in a fixed nut. An opening to receive the work to
be measured is provided by the backward movement of the
thimble which turns the screw and the size of the opening
is indicated by the graduations on the barrel.

406 Aviation Engines

The article to be measured is placed between the anvil
and spindle, the frame being held stationary while the
thimble is revolved by the thumb and finger. The pitch
of the screw thread on the concealed part of the spindle
is 40 to an inch. One complete revolution of the spindle,
therefore, moves it longitudinally one-fortieth, or twenty-
five thousandths of an inch. As will be evident from the
development of the scale on the barrel of the inch mi-
crometer, the sleeve is. marked with forty lines to the
inch, each of these lines indicating twenty-five thou-
sandths. . The thimble has a beveled edge which is gradu-
ated into twenty-five parts. When the instrument is
closed the graduation on the beveled edge of the thimble
marked should correspond to the line on the barrel.
If the micrometer is rotated one full turn the opening
between the spindle and anvil will be .025 inch. If the
thimble is turned only one graduation, or one twenty-
fifth of a revolution, the opening between the spindle and
anvil will be increased only by .001 inch, (one-thousandth
of an inch).

As many of the dimensions of the airplane parts,
especially of those of foreign manufacture or such parts
as ball and roller bearings, are based on the metric sys-
tem, the competent repairman should possess both inch
and metric micrometers in order to avoid continual refer-
ence to a table of metric equivalents. With a metric mi-
crometer there are fifty graduations on the barrel, these
representing .01 of a millimeter, or approximately .004
inch. One full turn of the barrel means an increase of
half a millimeter, or .50 mm. (fifty one-hundredths). As
it takes two turns to augment the space between the anvil
and the stem by increments of one millimeter, it will be
evident that it would not be difficult to divide the spaces
on the metric micrometer thimble in halves by the eye,
and thus the average workman can measure to .0002 inch
plus or minus without difficulty. As set in the illustra-
tion, the metric micrometers show a space of 13.5 mm.,
or about one millimeter more than half an inch. The

Micrometers and Their Use 407

inch, micrometer shown is set to five-tenths or five hun-
dred one-thousandths or one-half inch. A little study of
the foregoing matter will make if easy to understand th(
action of either the inch or metric micrometer.

Both of the micrometers shown have a small knurled
knob at the end of the barrel. This controls the ratchet
stop, which is a device that permits a ratchet to slip by
a pawl when more than a certain amount of pressure is
applied, thereby preventing the measuring spindle from
turning further and perhaps springing the instrument. A
simple rule that can be easily memorized for reading the
"inch micrometer is to multiply the number of vertical
divisions on the sleeve by 25 and add to that the number
of divisions on the bevel of the thimble reading from the
zero to the line which coincides with the horizontal line on
the sleeve. For example: if there are ten divisions visi-
ble on the sleeve, multiply this number by 25, then add
the number of divisions shown on the bevel of the thim-
ble, which is 10. The micrometer is therefore opened
10x25 equals 250 plus 10 equals 260 thousandths.

Micrometers are made in many sizes, ranging from
those having a maximum opening of one inch to special
large forms that will measure forty or more inches.
While it is not to be expected that the repairman will have
use for the big sizes, if a caliper having a maximum
opening of six inches is provided with a number of ex-
tension rods enabling one to measure smaller objects,
practically all of the measuring needed in repairing en-
gine parts can be made accurately. Two or three smaller
micrometers having a maximum range of two or three
inches will also be found valuable, as most of the measure-
ments will be made with these tools which will be much
easier to handle than the larger sizes.

TYPICAL TOOL OUTFITS

The equipment of tools necessary for repairing air-
plane engines depends entirely upon the type of the power

408 Aviation Engines

plant and while the common hand tools can be used on
all forms, the work is always facilitated by having special
tools adapted for reaching the nuts and screws that would
be hard to reach otherwise. Special spanners and socket
wrenches are very desirable. Then again, the nature of
the work to be performed must be taken into considera-
tion. Eebuilding or overhauling an engine calls for con-
siderably more tools than are furnished for making field
repairs or minor adjustments. A complete set of tools
supplied to men working on Curtiss OX-2 engines and
JN-4 training biplanes is shown at Fig. 179. The tools
are placed in a special box provided with a hinged cover
and are arranged in the systematic manner outlined.
The various tools and supplies shown are: A, hacksaw
blades; B, special socket wrenches for engine bolts and
nuts; C, ball pein hammers, four sizes; D, five assorted
sizes of screw drivers ranging from very long for heavy
work to short and small for fine work; -E, seven pairs of
pliers including combination in three sizes, two pairs of
cutting pliers and one round nose; F, two split pin ex-
tractors and spreaders; Gr, wrench set including three,
adjustable monkey wrenches, one Stilson or pipe wrench,
five sizes adjustable end wrenches and ten double end
S wrenches; H, set of files, including flat, three cornered
and half round; I, file brush; J, chisel and drift pin;
K, three small punches or drifts; L, hacksaw frame; M,
soldering copper; N, special spanners for propeller re-
taining nuts; 0, special spanners; P, socket wrenches,
long handle; Q, long handle, stiff bristle brushes for
cleaning motor; E, gasoline blow torch; S, hand drill;
T, spools of safety wire ; U, flash lamp ; V, special puller
and castle wrenches; W, oil can; X, large adjustable
monkey wrench; Y, washer and gasket cutter; Z, ball of
heavy twine. In addition to the tools, various supplies,
such as soldering acid, solder, shellac, valve grinding com-
pound, bolts and nuts, split pins, washers, wood screws,
etc., are provided.

410

Aviation Engines

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412 Aviation Engines

The special tools and fixtures recommended by the
Hall-Scott Company for work on their engines are clearly
shown at Fig. 180. All tools are numbered and their uses
may be clearly understood by reference to the illustra-
tion and explanatory list given on pages 410 and 411.

OVERHAULING AIRPLANE ENGINES

After an airplane engine has been in use for a period
ranging from 60 to 80 hours, depending upon the type,
it is necessary to give it a thorough overhauling before
it is returned to service. To do this properly, the engine
is removed from the fuselage and placed on a special sup-
porting stand, such as shown at Fig. 181, so it can be
placed in any position and completely dismantled. With
a stand of this kind it is as easy to work on the bottom
of the engine as on the top and every part can be in-
stantly reached. The crank-case shown in place in illus-
tration is in a very convenient position for scraping in
the crank-shaft bearings.

In order to look over the parts of an engine and to
restore the worn or defective components it is necessary
to take the engine entirely apart, as it is only when the
power plant is thoroughly dismantled that the parts can
be inspected or measured to determine defects or wear.
If one is not familiar with the engine to be inspected,
even though the work is done by a repairman of experi-
ence, it will be found of value to take certain precautions
when dismantling the engine in order to insure that all
parts will be replaced in the same position they occupied
before removal. There are a number of ways of identi-
fying the parts, one of the simplest and surest being to
mark them with steel numbers or letters or with a series
of center punch marks in order to retain the proper rela-
tion when reassembling. -This is of special importance
in connection with dismantling multiple cylinder engines
as it is vital that pistons, piston rings, connecting rods,
valves, and other cylinder parts be always replaced in

413

414

Aviation Engines

the same cylinder from which they were removed, be-
cause it is uncommon to find equal depreciation in all
cylinders. Some repairmen use small shipping tags to
identify the pieces. This can be criticised because the
tags may become detached and lost and the identity of

Fig. 181. Special Stand to Make Motor Overhauling Work Easier.

the piece mistaken. If the repairing is being done in a
shop where other engines of the same make are being
worked on, the repairman should be provided with a large
chest fitted with a lock and key in which all of the smaller
parts, such as rods, bolts and nuts, valves, gears, valve
springs, cam-shafts, etc., may be stored to prevent the
possibility of confusion with similar members of other

Dismantling an Engine 415

engines. All parts should be thoroughly cleaned with
gasoline or in the potash kettle as removed, and wiped
clean and dry. This is necessary to show wear which will
be evidenced by easily identified indications in cases
where the machine has been used for a time, but in others,
the deterioration can only be detected by delicate measur-
ing instruments.

In taking down a motor the smaller parts and fittings
such as spark-plugs, manifolds and wiring should be re-
moved first. Then the more important members such as cyl-
inders may be removed from the crank-case to give access
to the interior and make possible the examination of the
pistons, rings and connecting rods. After the cylinders are
removed the next operation is to disconnect the connect-
ing rods from the crank-shaft and to remove them and
the pistons attached as a unit. Then the crank-case -is
dismembered, in most cases by removing the bottom half
or oil sump, thus exposing the main bearings and crank-
shaft. The first operation is the removal of the inlet and
exhaust manifolds. In some cases the manifolds are
cored integral with the cylinder head casting and it is
merely necessary to remove a short pipe leading from the
carburetor to one inlet opening and the exhaust pipe from
the outlet opening common to all ' cylinders. In order to
remove the carburetor it is necessary to shut off the gaso-
line supply at the tank. and to remove the pipe coupling
at the float chamber. It is also necessary to disconnect
the throttle operating rod. After the cylinders are re-
moved and before taking the crank-case apart it is well
to remove the water pump and magneto. The wiring on
most engines of modern development is carried in con-
duits and usually releasing two or three minor fastenings
will permit one to take off the plug wiring as a unit.
The wire should be disconnected from both spark-plugs
and magneto distributor before its removal. When the
cylinders are removed, the pistons, piston rings, and con-
necting rods are clearly exposed and their condition may
be readily noticed.

416 Aviation Engines

Before disturbing the arrangement of the timing
gears, it is important that these be marked so that they
will be replaced in exactly the same relation as intended
by the engine designer. If the gears are properly marked
the valve timing and magneto setting will be undisturbed
when the parts are replaced after overhauling. With the
cylinders off, it is possible to ascertain if there is any
undue wear present in the connecting rod bearings at
either the wrist pin or crank-pin ends and also to form
some idea of the amount of carbon deposits on the piston
top and back of the piston rings. Any wear of the tim-
ing gears can also be determined. The removal of the
bottom plate of the engine enables the repairman to see
if the main bearings are worn unduly. Often bearings
may be taken up sufficiently to eliminate all looseness. In
other cases they may be worn enough so that careful
refitting will be necessary. Where the crank-case is
divided horizontally into two portions, the upper one
serving as an engine base to which the cylinders and in
fact all important working parts are attached, the lower
portion performs the functions of an oil container and
cover for the internal mechanism. This is the construc-
tion generally followed.

DEFECTS IN CYLINDERS

After the cylinders have been removed and stripped
of all fittings, they should be thoroughly cleaned and then
carefully examined for defects. The interior or bore
should be looked at with a view of finding score marks,
grooves, cuts or scratches in the interior, because there
are many faults that may be ascribed to depreciation at
this point. The cylinder bore may be worn out of round,
which can only be determined by measuring with an in-
ternal caliper or dial indicator even if the cylinder bore
shows no sign of. wear. The flange at the bottom of the
cylinder by which it is held to the engine base may be
cracked. The water jacket wall may have opened up due

Defects in Cylinders 417

to freezing of the jacket water at some time or other or it
may be filled with scale and sediment due to the use of
impure cooling water. The valve seat may be scored or
pitted, while the threads holding the valve chamber cap
may be worn so that the cap will not be a tight fit. The
detachable head construction makes it possible to remove
that member and obtain ready access to the piston tops
for scraping out carbon without taking the main cylinder
portion from the crank-case. When the valves need grind-
ing the head may be removed and carried to the bench
where the work may be performed with absolute assurance
that none of the valve grinding compound will penetrate
into the interior of the cylinder as is sometimes unavoid-
able with the I-head cylinder. If the cylinder should be
scored, the water jacket and combustion head may be
saved and a new cylinder casting purchased at consider-
ably less cost than that of the complete unit cylinder.

The detachable head construction has only recently
been applied on airplane engines, though it was one of
the earliest forms of automobile engine construction. In
the early days it was difficult to procure gaskets or pack-
ings that would be both gas and water tight. The sheet
asbestos commonly used was too soft and blew out read-
ily. Besides a new gasket had to be made every time
the cylinder head was removed. Woven wire and asbestos
packings impregnated with rubber, red lead, graphite and
other filling materials were more satisfactory than the
soft sheet asbestos, but were prone to burn out if the
water supply became low. Materials such as sheet copper
or brass proved to be too hard to form a sufficiently yield--
ing packing medium that would allow for the inevitable
slight inaccuracies in machining the cylinder head and
cylinder. The invention of the copper-asbestos gasket,
which is composed of two sheets of very thin, soft copper
bound together by a thin edging of the same material
and having a piece of sheet asbestos interposed solved
this problem. Copper-asbestos packings form an effec-
tive seal against leakage of water and a positive reten-

418 Aviation Engines

tion means for keeping the explosion pressure in the
cylinder. The great advantage of the detachable head is
that it permits of very easy inspection of the piston tops
and combustion chamber and ready removal of carbon
deposits.

CARBON DEPOSITS, THEIR CAUSE AND PREVENTION

Most authorities agree that carbon is the result of
imperfect combustion of the fuel and air mixture as well
as the use of lubricating oils of improper flash point.
Lubricating oils that work by the piston rings may be-
come decomposed by the great heat in the combustion
chamber, but at the same time one cannot blame the lubri-
cating oil for all of the carbon deposits. There is little
reason to suspect that pure petroleum oil of proper body
will deposit excessive amounts of carbon, though if the
oil is mixed with castor oil, which is of vegetable origin,
there would be much carbon left in the interior of the
combustion chamber. Fuel mixtures that are too rich in
gasoline also produce these undesirable accumulations.

A very interesting chemical analysis of a sample of
carbon scraped from the interior of a motor vehicle en-
gine shows that ordinarily the lubricant is not as much
to blame as is commonly supposed. The analysis was
as follows:

Oil 14.3%

Other combustible matter 17.9

Sand, clay, etc 24.8

Iron oxide 24.5

Carbonate of lime . 8.9

Other constituents , 9.6

It is extremely probable that the above could be di-
vided into two general classes, these being approximately
32.2% oil and 'combustible matter and a much larger
proportion, or 67.8% of earthy matter. The presence of
such a large percentage of earthy matter is undoubtedly
due to the impurities in the air, such as road dust which

Removal of Carbon Deposits 419

has been sucked in through the carburetor. The fact that
over 17-% of the matter which is combustible was not of
an oily nature lends strong support to this view. There
would not be the amount of earthy material present in
the carbon deposits of an airplane engine as above stated
because the air is almost free from dust at the high alti-
tudes planes are usually flown. One could expect to find
more combustible and less earthy matter and the carbon
would be softer and more easily removed. It is very good
practice to provide a screen on the air intake to reduce
the amounts of dust sucked in with the air as well as
observing the proper precautions relative to supplying
the proper quantities of air to the mixture and of not
using any more oil than is needed to insure proper lubri-
cation of the internal mechanism.

USE OF CARBON SCRAPERS

It is not unusual for one to hear an aviator complain
that the engine he operates is not as responsive as it was
when new after he has run it but relatively few hours.
There does not seem to be anything actually wrong with
the engine, yet it does not respond readily to the throttle
and is apt to overheat. While these symptoms denote a
rundown condition of the mechanism, the trouble is often
due to nothing more serious than accumulations of car-
bon. The remedy is the removal of this matter out of
place. The surest way of cleaning the inside of the motor
thoroughly is to remove the cylinders, if these members
are cast integrally with the head or of removing the head
member if 'that is a separate casting, to expose all parts.

In certain forms of cylinders, especially those of the
L form, it is possible to introduce simple scrapers down
through the valve chamber cap holes and through the
spark-plug hole if this component is placed in the cylin-
der in some position that communicates directly to the
interior of the cylinder or to the piston top. No claim
can be made for originality or novelty of this process as

420 Aviation Engines

is has been used for many years on large stationary en-
gines. The first step is to dismantle the inlet and ex-
haust piping and remove the valve caps and valves, al-
though if the deposit is not extremely hard or present
in large quantities one can often manipulate the scrapers
in the valve cap openings without removing either the
piping or the valves. Commencing with the first cylinder,
the crank-shaft is turned till the piston is at the top of
its stroke, then the scraper may be inserted, and the
operation of removing the carbon started by drawing the
tool toward the opening. As this is similar to a small
hoe, the cutting edge will loosen some of the carbon and
will draw it toward the opening. A swab is made of a
piece of cloth or waste fastened at the end of a wire and
well soaked in kerosene to clean out the cylinder.

When available, an electric motor with a length of
flexible shaft and a small circular cleaning brush having
wire bristles can be used in the interior of the engine.
The electric motor need not be over one-eighth horse-
power running 1,200 to 1,600 E. P. M., and the wire brush
must, of course, be of such size that it can be easily in*
serted through the valve chamber cap. The flexible shaft
permits one to reach nearly all parts of the cylinder in-
terior without difficulty and the spreading out and flatten-
ing of the brush insures that considerable surface will be
covered by that member.

BURNING OUT CARBON WITH OXYGEN

A process of recent development that gives very good
results in removing carbon without disassembling the
motor depends on the process of burning out that ma-
terial by supplying oxygen to support the combustion
and to make it energetic. A number of concerns are al-
ready offering apparatus to accomplish this work, and in
fact any shop using an autogenous welding outfit may
use the oxygen tank and reducing valve in connection
with a simple special torch for burning the carbon. Ke-

Carbon Removal

421

suits have demonstrated that there is little danger of
damaging the motor parts, and that the cost of oxygen
and labor is much lower than the old method of removing
the cylinders and scraping the carbon out, as well as
being very much quicker than the alternative process of
using carbon solvent. The only drawback to this system
is that there is no absolute insurance that every particle
of carbon will be removed, as small protruding particles
may be left at* points that the flame does not reach and

Trigger Valve

,'Ma'm
Valve

Where Carbon Deposits
collect in Combust/on Head

Hose-

Pressure
Regulator

Fig. 182. Showing Where Carbon Deposits Collect in Engine Combustion
Chamber, and How to Burn Them Out with the Aid of Oxygen. A
Special Torch. B Torch Coupled to Oxygen Tank. C Torch in Use.

cause pre-ignition and consequent pounding, even after
the. oxygen treatment. It is generally known that carbon
will burn in the presence of oxygen, which supports com-
bustion of all materials, and this process takes advantage
of this fact and causes the gas to be injected into the
combustion chamber over a flame obtained by a match or
wax taper.

li is suggested by those favoring this process that
the night before the oxygen is to be used the engine be
given a conventional kerosene treatment. A half tumbler
full of this liquid or of denatured alcohol is to be poured

422 Aviation Engines

into each cylinder and permitted to remain there over
night. As a precaution against fire, the gasoline is shut
off from the carburetor before the torch is inserted in
the cylinder and the motor started so that the gasoline in
the pipe and carburetor float chamber will be consumed.
Work is done on one cylinder at a time. A note of cau-
tion was recently sounded by a prominent spark-plug
manufacturer recommending that the igniter member be
removed from the cylinder in order not to injure it by
the heat developed. The outfits on the market consist
of a special torch having a trigger controlled valve and
a length of flexible tubing such as shown at Fig. 182, A,
and a regulating valve and oxygen tank as shown at B.
The gauge should be made to register about twelve
pounds pressure.

The method of operation is very simple and is out-
lined at C. The burner tube is placed in the cylinder and
the trigger valve is opened and the oxygen permitted to
circulate in the combustion chamber. A lighted match
or wax taper is dropped in the chamber and the injector
tube is moved around as much as possible so as to cover
a large area. The carbon takes fire and burns briskly in
the presence of the oxygen. The combustion of the car-
bon is accompanied by sparks and sometimes by flame if
the deposit is of an oily nature. Once the carbon begins
to burn the combustion continues without interruption as
long as the oxygen flows into the cylinder. Full instruc-
tions accompany each outfit and the amount of pressure
for which the regulator should be set depends upon 'the
design of the torch and the amount of oxygen contained
in the storage tank.

REPAIRING SCORED CYLINDERS

If the engine has been run at any time without ade-
quate lubrication, one or more of the cylinders may be
found to have vertical scratches running up and down
the cylinder walls. The depth of these will vary accord-

Repairing Scored Cylinders 423

ing to the amount of time the cylinder was without lubri-
cation, and if the grooves are very deep the only remedy
is to purchase a new member. Of course, if sufficient
stock is available in the cylinder walls, the cylinders may
be rebored and new pistons which are oversize, i.e., larger
than standard, may be fitted. Where the scratches are
not deep they may be ground out with a high speed emery
wheel or lapped out if that type of machine is not avail-
able. Wrist pins have been known to come loose, espe-
cially when these are retained by set screws that are not
properly locked, and as wrist-pins are usually of hard-
ened steel it will be evident that the sharp edge of that
member can act as a cutting tool and make a pronounced
groove in the cylinder. Cylinder grinding is a job that
Requires skilled mechanics, but may be accomplished on
any lathe fitted with an internal grinding attachment.
While automobile engine cylinders usually have sufficient
wall thickness to stand reboring, those of airplane engines
seldom have sufficient metal to permit of enlarging the
bore very much by a boring tool. A few thousandths of
an inch may be ground out without danger, however.
An airplane engine cylinder with deep grooves must be
scrapped as a general rule.

Where the grooves in the cylinder are not deep or
where it has warped enough so the rings do not bear
equally at all parts of the cylinder bore, it is possible to
obtain a fairly accurate degree of finish by a lapping pro-
cess in which an old piston is coated with a mixture of
fine emery and oil and is reciprocated up and down in the
cylinder as well as turned at the same time. This may
be easily done by using a dummy connecting rod having
only a wrist pin end boss, and of such size at the other
end so that it can be held in the chuck of a drill press.
The cylinder casting is firmly clamped on the drill press
table by suitable clamping blocks, and a wooden block is
placed in the combustion chamber to provide a stop for
the piston at its lower extreme position. The back gears
are put in and the drill chuck is revolved slowly. All the

424 Aviation Engines

while that the piston is turning the drill chuck should be
raised up and down by the hand feed lever, as the best
results are obtained when the lapping member -is given
a combination of rotary and reciprocating motion.

VALVE* REMOVAL, AND INSPECTION

One of the most important parts of the gasoline en-
gine and one that requires frequent inspection and refit-
ting to keep in condition, is the mushroom or poppet valve
that controls the inlet and exhaust gas flow. In over-
hauling it is essential that these valves be removed from
their seatings and examined carefully for various defects
which will be enumerated at proper time. The problem
that concerns us now is the best method of removing the-
valve. These are held against the seating in the cylinder
by a coil spring which exerts its pressure on the cylinder
casting at the upper end and against a suitable collar
held by a key at the lower end of the valve stem. In
order to remove the valve it is necessary to first com-
press the spring by raising the collar -and pulling the
retaining key out of the valve stem. Many forms of valve
spring lifters have been designed to permit ready re-
moval of the valves.

When the cylinder is of the valve in-the-head form,
the method of valve removal will depend entirely upon
the system of cylinder construction followed. In the
Sturtevant cylinder design it is possible to remove the
head from the cylinder castings and the valve springs
may be easily compressed by any suitable means when
the cylinder head is placed on the work bench where it
can be easily worked on. The usual method is to place
the head on a soft cloth with the valves bearing against
the bench. The valve springs may then be easily pushed
down with a simple forked lever and the valve stem key
removed to release the valve spring collar. In the Curtiss
OX-2 (see Fig. 182%) and Hall-Scott engines it is not
possible to remove the valves without taking the cylinder

Valve Removal and Inspection

425

off the crank-case, because the valve seats are machined
directly in the cylinder head and the valve domes are cast
integrally with the cylinder. This means that if the valves
need grinding the cylinder must be removed from the
engine base to provide access to the valve heads which
are inside of that member, and which cannot be reached

fnlet. Valve
Spring -

/n/ef Port

Water
Outlet

Water .Space

Exhaust

Valve Spring

Cylinder ^

pplied Wafer
' Jacket

Cylinder

m*~Cool Water
P" Jn let

Base

Flange

Fig. 182y 2 . Part Sectional View, Showing Valve Arrangement in Cylinder
of Curtiss OX-2 Aviation Engine.

from the outside as is true of the L-cylinder construction.
In the Curtiss VX engines, the valves are carried in de-
tachable cages which may be removed when the valves
need attention.

RESEATING AND TRUING VALVES

Much has been said relative to valve grinding, and
despite the mass of information given in the trade prints

426 Aviation Engines

it is rather amusing to watch the average repairman or the
engine user who prides himself on maintaining his own
motor performing this essential operation. The common
mistakes are attempting to seat a badly grooved or pitted
valve head on an equally bad seat, which is an almost
hopeless job, and of using coarse emery and bearing down
with all one's weight on the grinding tool with the hope
of quickly wearing away the rough surfaces. The use of
improper abrasive material is a fertile cause of failure
to obtain a satisfactory seating. Valve grinding is not a
difficult operation if certain precautions are taken before
undertaking the work. The most important of these is
to ascertain if the valve head or seat is badly scored or
pitted. If such is found to be the case no ordinary
amount of grinding will serve to restore the surfaces. In
this event the best thing to do is to remove the valve
from its seating and to smooth down both the valve head
and the seat in the cylinder before attempt is made to
fit them together by grinding. Another important pre-
caution is to make sure that the valve stem is straight,
and that the head is not warped out of shape.

A number of simple tools is available at the present
time for reseating valves, these being outlined at Fig.
183. That shown at A is a simple fixture for facing off
the valve head. The stem is supported by suitable bear-
ings carried by the body or shank of the tool, and the
head is turned against an angularly disposed cutter which
is set for the proper valve seat angle. The valve head
is turned by a screw-driver, the amount of stock removed
from the head depending upon the location of the adjust-
ing screw. Care must be taken not to remove too much
metal, only enough being taken off to remove the most
of the roughness. Valves are made in two standard
tapers, the angle being either 45 or 60 degrees. It is im-
perative that the cutter blade be set correctly in order
that the bevel is not changed. A set of valve truing and
valve-seat reaming cutters is shown at Fig. 183, B. This
is adaptable to various size valve heads, as the cutter

Valve Restoration

42?

blade D may be moved to correspond to the size of the
valve head being trued up. These cutter blades are made

ooy

Fig. 183. Tools for Restoring Valve Head and Seats.

of tool steel and have a bevel at each end, one at 45 de-
grees, the other at 60 degrees. The valve seat reamer
shown at G will take any one of the heads shown at F.

428 Aviation Engines

It will also take any one of the guide bars shown at H.
The function of the guide bars is to fit the valve stem
bearing in order to locate the reamer accurately and to
insure that the valve seat is machined concentrically with
its normal center. Another form of valve seat reamer
and a special wrench used to turn it is shown at C. The
valve head truer shown at Fig. 183, D, is intended to be
placed in a vise and is adaptable to a variety of valve
head sizes. The smaller valves merely fit deeper in the
conical depression. The cutter blade is adjustable and
the valve stem is supported by a simple self-centering
bearing. In operation it is intended that the valve steni,
which protrudes through the lower portion of the guide
bearing, shall be turned by a drill press or bit stock while
the valve head is set against the cutter by pressure of a
pad carried at the end of a feed screw which is supported
by a hinged bridge member. This can be swung out of
place as indicated to permit placing the valve head against
the cutter .or removing it.

As the sizes of valve heads and stems vary consider-
ably a "Universal" valve head truing tool must have
some simple means of centering the valve stem in order
to insure concentric machining of the valve head. A valve
head truer which employs an ingenious method of guid-
ing the valve stem is shown at Fig. 183, E. The device
consists of a body portion, B, provided with an external
thread at the top on which the cutter head, A, is screwed.
A number of steel balls, C, are carried in the grooves
which may be altered in size by the adjustment nut, F,
which screws in the bottom of the body portion, B. As
the nut F is screwed in against the . spacer member E,
the V-grooves are reduced in size and the steel balls, C,
are pressed out in contact with the valve stem. As the
circle or annulus is filled with balls in both upper and
lower portions the stem may be readily turned because
it is virtually supported by ball bearing guides. When
a larger valve stem is to be supported, the adjusting nut
F, is screwed out which increases the size of the grooves

Valve Grinding Processes 429

and permits the balls, C, to spread out and allow the larger
stem to be inserted.

VALVE GRINDING PROCESSES

Mention has been previously made of the importance
of truing both valve head and seat before attempt is made
to refit the parts by grinding. After smoothing the valve
seat the next step is to find some way of turning the valve.
Valve heads are usually provided with a screw-driver slot
passing through the boss at the top of the valve or with
two drilled holes to take a forked grinding tool. A com-
bination grinding tool has been devised which may be
used when either the two drilled holes or the slotted head
form of valve is to be rotated. This consists of a special
form of screw driver having an enlarged boss just above
the blade, this boss serving to support a U-shape piece
which can be securely held in operative position by the
clamp screw or which can be turned out of the way if
the screw driver blade is to be used.

As it is desirable to turn the valve through a portion
of a revolution and back again rather than turning it
always in the same direction, a number of special tools
has been designed to make this oscillating motion possible
without trouble. A simple valve grinding tool is shown
at Fig. 184, C. This consists of a screw-driver blade
mounted in a handle in such a way that the end may
turn freely in the handle. A pinion is securely fastened
to the screw-driver blade shank, and is adapted to fit a
race provided with a wood handle and guided by a bent
bearing member securely fastened to the screw-driver
handle. As the rack is pushed back and forth the pinion
must be turned first in one direction and then in the other.

A valve grinding tool patterned largely after a breast
drill is shown at Fig. 184, D. This is worked in such a
manner that a continuous rotation of the operating crank
will result in an oscillating movement of the chuck carry-
ing the screw-driver blade. The bevel pinions which are

1.30

Aviation Engines

used to turn the chuck are normally free unless clutched
to the chuck stem by the sliding sleeve which must turn
with the chuck stem and which carries clutching members

Valve

-Valve Cage

Va/ve Stem
-Na/f

'Valve Stem

Fig. 184. Tools and Processes Utilized in Valve Grinding.

at each end to engage similar members on the bevel pin-
ions and lock these to the chuck stem, one at a time. The
bevel gear carries a cam-piece which moves the clutch

Valve Grinding Processes 431

sleeve back and forth as it revolves. This means that the
pinion giving forward motion of the chuck is clutched to
the chuck spindle for a portion of a revolution of the
gear and clutch sleeve is moved back by the cam and
clutched to the pinion giving a reverse motion of the
chuck during the remainder of the main drive gear revo-
lution.

It sometimes happens that the adjusting screw on the
valve lift plunger or the valve lift plunger' itself when
L head cylinders are used does not permit the valve head
to rest against the seat. It will be apparent that unless
a definite space exists between the end of the valve stem
and the valve lift plunger that grinding will be of little
avail because the valve head will not bear properly
against the abrasive material smeared on the valve seat.

The usual methods of valve grinding are clearly out-
lined at Fig. 184. The view at the left shows the method
of turning the valve by an ordinary screw driver and also
shows a valve head at A, having both the drilled holes
and the screw-driver slot for turning the member and two
special forms of fork-end valve grinding tools. In the
sectional view shown at the right, the use of the light
spring between the valve head and the bottom of the valve
chamber to lift the valve head from the seat whenever
pressure on the grinding tool is released is clearly indi-
cated. It will be noted also that a ball of waste or cloth
is interposed in the passage between the valve chamber
and the cylinder interior to prevent the abrasive material
from passing into the cylinder from the valve chamber.
When a bitstock is used, instead of being given a true
rotary motion the chuck is merely oscillated through the
greater part of the circle and back again. It is necessary
to lift the valve from its seat frequently as the grinding
operation continues; this is to provide an even distribu-
tion of the abrasive material placed between the valve
head and its seat. Only sufficient pressure is given to
the bitstock to overcome the uplift of the spring and to
insure that the valve will be held against the seat. Where

432 Aviation Engines

the spring is not used it is possible to raise the valve
from time to time with the hand which is placed under
the valve stem to raise it as the grinding is carried on.
It is not always possible to lift the valve in this manner
when the cylinders are in place on the engine base owing
to the space between the valve lift plunger and the end
of the valve stem. In this event the use of the spring as
shown in sectional view will be desirable.

The abrasive generally used is a paste made of
medium or fine emery and lard oil or kerosene. This is
used until the surfaces are comparatively smooth, after
which the final polish or finish is given with a paste of
flour emery, grindstone dust, crocus, or ground glass and
oil. An erroneous impression prevails in some quarters
that the valve head surface and the seating must have
a mirror-like polish. While this is not necessary it is
essential that the seat in the cylinder and the bevel sur-
face of the head be smooth and free from pits or scratches
at the completion of the operation. All traces of the
emery and oil should be thoroughly washed out of the
valve chamber with gasoline before the valve mechanism
is assembled and in fact it is advisable to remove the old
grinding compound at regular intervals, wash the seat
thoroughly and supply fresh material as the process is in
progress.

The truth of seatings may be tested by taking some
Prussian blue pigment and spreading a thin film of it
over the valve seat. The valve is dropped in place and
is given about one-eighth turn with a little pressure on
the tool. If the seating is good both valve head and seat
will be covered uniformly with color. If high spots exist,
the heavy deposit of color will show these while the low
spots will be made evident because of the lack of pig-
ment. The grinding process should be continued until
the test shows an even bearing of the valve head at all
points of the cylinder seating. When the valves are held
in cages it is possible to catch the cage in a vise and to
turn the valve in any of the ways indicated. It is much

Depreciation In Valve Systems 433

easier to clean off the emery and oil and there is abso-
lutely no danger of getting the abrasive material in the
cylinder if the construction is such that the valve cage
or cylinder head member carrying the valve can be re-
moved from the cylinder. When valves are held in cages,
the tightness of the seat may be tested by partially filling
the cage with gasoline and noticing how much liquid oozes
out around the valve head. The degree of moisture pres-
ent indicates the efficacy of the grinding process.

The valves of Curtiss OX-2 cylinders are easily
ground in by using a simple fixture or tool and working
from the top of the cylinder instead of from the inside.
A tube having a bore just large enough to go over the
valve stem is provided with a wooden handle or taped at
one end and a hole of the same size as that drilled through
the valve stem is put in at the other. To use, the open
end of the tube is pushed over the valve stem and a split
pin pushed through the tube and stem. The valve may
be easily manipulated and ground in place by oscillating
in the customary manner.

DEPRECIATION- IN VALVE OPERATING SYSTEMS

There are a number of points to be watched in the
valve operating system because valve timing may be seri-
ously interfered with if there is much lost motion at the
various bearing points in the valve lift mechanism. The
two conventional methods of opening valves are shown at
Fig. 185. That at A is the type employed when the valve
cages are mounted directly in the head, while the form at
B is the system used when the valves are located in a
pocket or extension of the cylinder casting as is the case
if an L, or T-head cylinder is used. It will be evident
that there are several points where depreciation may take
place. The simplest form is that shown at B, and even on
this there are five points where lost motion may be noted.
The periphery of the valve opening cam or roller may be
worn, though this is not likely unless the roller or cam has

434

Aviation Engines

been inadvertently left soft. The pin which acts as a
bearing for the roller may become worn, this occurring
quite often. Looseness may materialize between the bear-
ing surfaces of the valve lift plunger and the plunger

.-Rocker Lever

Fulcrum.

-Tappet Rod

,.- Valve Plunger-' J|_,

--,- Valve -Plunger
Guide .......

Valve

Rocker firm.

/ Fulcrum Pin,

Valve Spring^

Cage
Retaining,
Nut '

Pin.

Vafve
5 Stem

''Valve -Operating Caws-

Fig. 185. Outlining Points in Valve Operating Mechanism Where Depre-
ciation is Apt to Exist.

guide casting, and there may also be excessive clearance
between the top of the plunger and the valve stem.

On the form shown at A, there are several parts added
to those indicated at B. A walking beam or rocker lever
is necessary to transform the upward motion of the tappet
rod to a downward motion of the' valve stem. The pin

Depreciation In Valve Systems 435

on which this member fulcrums may wear as will also the
other pin acting as a hinge or bearing for the yoke end
of the tappet rod. It will be apparent that if slight play
existed at each of the points mentioned it might result in
a serious diminution of valve opening. Suppose, for ex-
ample, that there were .005-inch lost motion at each of
three bearing points, the total lost motion would be .015-
inch or sufficient to produce noisy action of the valve
mechanism. When valve plungers of the adjustable form,
such as shown at B, are used, the hardened bolt head in
contact with the end of the valve stem may become hol-
lowed out on account of the hammering action at that
point. It is imperative that the top of this member be
ground off true and the clearance between the valve stem
and plunger properly adjusted. If the plunger is a non-
adjustable type it will be necessary to lengthen the valve
stem by some means in order to reduce the excessive
clearance. The only remedy for wear at the various
hinges and bearing pins is to bore the holes out slightly
larger and to fit new hardened steel pins of larger diam-
eter. Depreciation between the valve plunger guide and
the valve plunger is usually remedied by fitting new
plunger guides in place of the worn ones. If there is
sufficient stock in the plunger guide casting as is some-
times the case when these members are not separable from
the cylinder casting, the guide may be bored out and
bushed with a light bronze bushing.

A common cause of irregular engine operation is due to
a sticking valve. This may be owing to a bent valve stem,
a weak or broken valve spring or an accumulation of
burnt or gummed oil between the valve stem and the
valve stem guide. In order to prevent this the valve stem
must be smoothed with fine emery cloth and no burrs or
shoulders allowed to remain on it, and the stem must also
be straight and at right angles to the valve head. If the
spring is weak it may be strengthened in some cases by
stretching it out after annealing so that a larger space
will exist between the coils and re-hardening. Obviously

436 Aviation Engines

if a spring is broken the only remedy is replacement of
the defective member.

Mention has been made of wear in the valve stem
guide and its influence on engine action. When these
members are an integral part of the cylinder the only
method of compensating for this wear is to drill the guide
out and fit a bushing, which may be made of steel tube.

In some engines, especially those of recent develop-
ment, the valve stem guide is driven or screwed into the
cylinder casting and is a separate member which may be
removed when worn and replaced with a new one. When
the guides become enlarged to such a point that con-
siderable play exists between them and the valve stems,
they may be easily knocked out or unscrewed.

PISTON TROUBLES

If an engine has been entirely dismantled it is very
easy to examine the pistons for deterioration. While it
is important that the piston be a good fit in the cylinder
it is mainly upon the piston rings that compression de-
pends. The piston should fit the cylinder with but little
looseness, the usual practice being to have the piston
about .001-inch smaller than the bore for each inch of
piston diameter at the point where the least heat is pres-
ent or at the bottom of the piston. It is necessary to
allow more than this at the top of the piston owing to its
expansion due to -the direct heat of the explosion. The
clearance is usually graduated and a piston that would be
.005-inch smaller than the cylinder bore at the bottom
would be about .0065-inch at the middle and .0075-inch at
the top. If much more play than this is evidenced the
piston will "slap" in the cylinder and the piston will be
worn at the ends more than in the center. Aluminum or
alloy pistons require more clearance than cast iron ones
do, usually 1.50 times as much. Pistons sometimes warp
out of shape and are not truly cylindrical. This results
in the high spots rubbing on the cylinder while the low

Piston and Ring Troubles 437

spots will be blackened where a certain amount of gas
has leaked by.

Mention has been previously made of the necessity of
reboring or regrinding a cylinder that has become scored
or scratched and which allows the gas to leak by the
piston rings. When the cylinder is ground out, it is nec-
essary to use a larger piston to conform to the enlarged
cylinder bore. Most manufacturers are prepared to fur-
nish orer-size pistons, there being four standard over-
size dimensions adopted by the S. A. E. for rebored
cylinders. These are .010-inch, .020-inch, .030-inch, and
.040-inch larger than the original bore.

The piston rings should be taken out of the piston
grooves and all carbon deposits removed from the inside
of the ring and the bottom of the groove. It is important
to take this deposit out because it prevents the rings
from performing their proper functions by reducing the
ring elasticity, and if the deposit is allowed to accumulate
it may eventually result in sticking and binding of the
ring, this producing excessive friction or loss of compres-
sion. When the rings are removed they should be tested
to see if they retain their elasticity and it is also well to
see that the small pins in some pistons which keep the
rings from turning around so the joints will not come in
line are still in place. If no pins are found there is no
cause for alarm because these dowels are not always
used. When fitted, they are utilized with rings having a
butt joint or diagonal cut as the superior gas retaining
qualities of the lap or step joint render the pins un-
necessary.

If gas has been blowing by the ring or if these mem-
bers have. not been fitting the cylinder properly the points
where the gas passed will be evidenced by burnt, brown
or roughened portions of the polished surface of the
pistons and rings. The point where this discoloration
will be noticed more often is at the thin end of an eccen-
tric ring, the discoloration being present for about %-inch
or %-inch each side of the slot. It may be possible that

438 Aviation Engines

the rings were not true when first put in. This made it
possible for the gas to leak by in small amounts initially
which increased due to continued pressure until quite a
large area for gas escape had been created.

PISTON KING MANIPULATION

Eemoving piston rings without breaking them is a dif-
ficult operation if the proper means are not taken, .but is
a comparatively simple one when the trick is known. The
tools required are very simple, being three strips of thin
steel about one-quarter inch wide and four or five inches
long and a pair of spreading tongs made up of one-
quarter inch diameter keystock tied in the center with a
copper wire to form a hinge. The construction is such
that when the hand is closed and the handles brought to-
gether the other end of the expander spreads out, an
action just opposite to that of the conventional pliers.
The method of using the tongs and the metal strips is
clearly indicated at Fig. 186. At A the ring expander is
shown spreading the ends of the rings sufficiently to insert
the pieces of sheet metal between one of the rings and the
piston. Grasp the ring as shown at B, pressing with the
thumbs on the top of the piston and the ring will slide off
easily, the thin metal strips acting as guide members to
prevent the ring from catching in the other piston grooves.
Usually no difficulty is experienced in removing the top
or bottom rings, as these members may be easily expanded
and worked off directly without the use of a metal strip.
When removing the intermediate rings, however, the metal
strips will be found very useful. These are usually made
by the repairman by grinding the teeth from old hacksaw
blades and rounding the edges and corners in order to re-
duce the liability of cutting the fingers. By the use of the
three metal strips a ring is removed without breaking or
distorting it and practically no time is consumed in the
operation.

Piston Ring Manipulation 439

FITTING PISTON RINGS

Before installing new rings, they should be carefully
fitted to the grooves to which they are applied. The tools
required are a large piece of fine emery cloth, a thin, flat
file, a small vise with copper or leaden jaw clips, and a
smooth hard surface such as that afforded by the top of
a surface plate or a well planed piece of hard wood. After
making sure that all deposits of burnt oil and carbon have
been removed from the piston grooves, three rings are
selected, one for each groove. The ring is turned all
around its circumference into the groove it is to fit, which
can be done without springing it over the piston as the
outside edge of the ring may be used to test the width of
the groove just as well as the inside edge. The ring should
be a fair fit and while free to move circumferentially there
should be no appreciable up and down motion. If the
ring is a tight fit it should be laid edge down upon the
piece of emery cloth which is placed on the surface plate
and carefully rubbed down until it fits the groove it is to
occupy. It is advisable to fit each piston ring individually
and to mark them in some way to insure that they will be
placed in the groove to which they are fitted.

The repairman next turns his attention to fitting the
ring in the cylinder itself. The ring should be pushed
into the cylinder at least two inches up from the bottom
and endeavor should be made to have the lower edge of
the ring parallel with the bottom of the cylinder. If the
ring is not of correct diameter, but is slightly larger than
the cylinder bore, this condition will be evident by the
angular slots of the rings being out of line or by difficulty
in inserting the ring if it is a lap joint form. If such is
the case the ring is removed from the cylinder and placed
in the vise between soft metal jaw clips. Sufficient metal
is removed with a fine file from the edges of the ring at
the slot until the edges come into line and a slight space
exists between them when the ring is placed into the cylin-
der. It is important that this space be left between the

440

Aviation Engines

ends, for if this is not done when the ring becomes heated
the expansion of metal may cause the ends to abut and
the ring to jam in the cylinder.

It is necessary to use more than ordinary caution in
replacing the rings on the piston because they are usually

.-Thin Metal

'Piston
Ring

Ring Expander

^Clamping Ring--''

Fig. 186. Method of Removing Piston Rings, and Simple Clamp to Facili-
tate Insertion of Rings in Cylinder.

made of cast iron, a metal that is very fragile and liable
to break because of its brittleness. Special care should
be taken in replacing new rings as these members are

Piston Ring Manipulation 441

more apt to break than old ones. This is probably ac-
counted for by the heating action on used rings which
tends to anneal the metal as well as making it less springy.
The bottom ring should be placed in position first which
is easily accomplished by springing the ring open enough
to pass on the piston and then sliding it into place in the
lower groove which on some types of engines is below
the wrist pin, whereas in others all grooves are above that
member. The other members are put in by a reversal of
the process outlined at Fig. 186, A and B. It is not always
necessary to use the guiding strips of metal when replac-
ing rings as it is often possible, by putting the rings on
the piston a little askew and maneuvering them to pass
the grooves without springing the ring into them. The
top ring should be the last one placed in position.

Before placing pistons in the cylinder one should make
sure that the slots in the piston rings are spaced equidis-
tant on the piston, and if pins are used to keep the ring
from turning one should be careful to make sure that these
pins fit into their holes in the ring and that they are not
under the ring at any point. Practically all cylinders are
chamfered at the lower end to make insertion of piston
rings easier. The operation of putting on a cylinder cast-
ing over a piston really requires two pairs of hands, one
to manipulate the cylinder, the other person to close the
rings as they enter the cylinder. This may be done very
easily by a simple clamp member made of sheet brass or
iron and used to close the ring as indicated at Fig. 186, C.
It is apparent that the clamp must be adjusted to each
individual ring and that the split portion of the clamp
must coincide with the split portion of the ring. The
cylinder should be well oiled before any attempt is made to
install the pistons. The engine should be run with more
than the ordinary amount of lubricant for several hours
after new piston rings have been inserted. On first start-
ing the engine, one may be disappointed in that the com-
pression is even less than that obtained with the old rings.
This condition will soon be remedied as the rings become

442 Aviation Engines

polished and adapt themselves to the contour of the
cylinder.

WRIST PIN WEAR

While wrist pins are usually made of very tough steel,
case hardened with the object of wearing out an easily
renewable bronze bushing in the upper end of the connect-
ing rod rather than the wrist pin it sometimes happens
that these members will be worn so that even the re-
placement of a new bushing in the connecting rod will
not reduce the lost motion and attendant noise due to a
loose wrist pin. The only remedy is to fit new wrist pins
to the piston. Where the connecting rod is clamped to
the wrist pin and that member oscillates in the piston
bosses the wear will usually be indicated on bronze bush-
ings which are pressed into the piston bosses. These are
easily renewed and after running a reamer through them
of the proper size no difficulty should be experienced in
replacing either the old or a new wrist pin depending
upon the condition of that member. If no bushings are
provided, as in alloy pistons, the bosses can sometimes
be bored out and thin bushings inserted, though this is
not always possible. The alternative is to ream out the
bosses and upper end of rod a trifle larger after holes are
trued up and fit oversize wrist pins.

INSPECTION AND REFITTING OF ENGINE BEARINGS ,

While the engine is dismantled one has an excellent
opportunity to examine the various bearing points in the
engine crank-case to ascertain if any looseness exists due
to depreciation of the bearing surfaces. As will be evi-
dent, both main crank-shaft bearings and the lower end
of the connecting rods may be easily examined for de-
terioration. With the rods in place, it is not difficult to
feel the amount of lost motion by grasping the connect-
ing rod firmly with the hand and moving it up and down.
After the connecting rods have been removed and the

Refitting Engine Bearings 443

propeller hub taken off the crank-shaft to permit of ready
handling, any looseness in the main bearing may be de-
tected by lifting up on either the front or rear end of
the crank-shaft and observing if there is any lost motion
between the shaft journal and the main bearing caps.
It is not necessary to take an engine entirely apart to
examine the main bearings, as in most forms these may be
readily reached by removing the sump. The symptoms
of worn main bearings are not hard to identify. If an
engine knocks regardless of speed or spark-lever position,
and the trouble is not due to carbon deposits in the com-
bustion chamber, one may reasonably surmise that the
main bearings have become loos.e or that lost motion may
exist at the connecting rod big ends, and possibly at the
wrist pins. The main journals of any well resigned en-
gine are usually proportioned with ample surface and
will not wear unduly unless lubrication has been neg-
lected. The connecting rod bearings wear quicker than
the main bearings owing to being subjected to a greater
unit stress, and it may be necessary to take these up.

ADJUSTING MAIN BEARINGS

When the bearings are not worn enough to require
refitting the lost motion can often be eliminated by re-
moving one or more of the thin shims or liners ordinarily
used to separate the bearing caps from the seat. These
are shown at Fig. 187, A. Care must be taken that an
even number -of shims of the same thickness are removed
from each side of the journal. If there is considerable
lost motion after one or two shims have been removed,
it will be advisable to take out more shims and to scrape
the bearing to a fit before the bearing cap is tightened
up. It may be necessary to clean up the crank- shaft
journals as these may be scored due to not having re-
ceived clean oil or having had bearings seize upon them.
It is not difficult to true up the crank-pins or main jour-
nals if the score marks are not deep. A fine file and

,>-Emery Cloth

Shims,

"' Box

Bearing
Cap --' A

Tig. 187. Tools and Processes Used in Befitting Engine Bearings.

444

Refitting Engine Bearings 445

emery cloth may be used, or a lapping tool such as de-
picted at Fig. 187, B. The latter is preferable because
the file and emery cloth will only tend to smooth the sur-
face while the lap will have the effect of restoring the
crank to proper contour.

A lapping tool may be easily made, as shown at B, the
blocks being of lead or hard wood. As the width of these
are about half that of the crank-pin the tool may be
worked from side to side as it is rotated. An abrasive
paste composed of fine emery powder and oil is placed
between the blocks, and the blocks are firmly clamped to
the crank-pin. As the lead blocks bed down, the wing
nut should be tightened to insure that the abrasive will be
held with some degree of pressure against the shaft. A
liberal supply of new abrading material is placed between
the lapping blocks and crank-shaft from time to time and
the old mixture cleaned off with gasoline. It is necessary
to maintain a side to side movement of the lapping tool
in order to have the process affect the whole width of the
crank-pin equally. The lapping is continued until a
smooth surface is obtained. If a crank-pin is worn out
of true to any extent the only method of restoring it is
to have it ground down to proper circular form by a
competent mechanic having the necessary machine tools
to carry on the work accurately. A crank-pin truing
tool that may be worked by hand is shown at Fig. 187, K.

After the crank-shaft is trued the next operation is to
fit it to the main bearings or rather to scrape these mem-
bers to fit the shaft journal. In order to bring the brasses
closer together, it may be necessary to remove a little
metal from the edges of the caps to compensate for the
lost motion. A very simple way of doing this is shown
at Fig. 187, D. A piece of medium emery cloth is rested
on the surface plate and the box or brass is pushed back
and forth over that member by hand, the amount of pres-
sure and rapidity of movement being determined by the
amount of metal it is necessary to remove. This is better
than filing, because the -edges will be flat and there will be

446 Aviation Engines

no tendency for the bearing caps to rock when placed
against the bearing seat. It is important to take enough
off the edges of the boxes to insure that they will grip
the crank tightly. The outer diameter must be checked
with a pair of calipers during this operation to make sure
that the surfaces remain parallel. Otherwise, the bearing
brasses will only grip at one end and with such insuffi-
cient support they will quickly work loose, both in the
bearing seat and bearing cap.

SCRAPING BRASSES TO FIT

To insure that the bearing brasses will be a good fit
on the trued-up crank-pins or crank-shaft journals, they
must be scraped to fit the various crank-shaft journals.
The process of scraping, while a tedious one, is not diffi-
cult, requiring only patience and some degree of care to
do a good job. The surface of the crank-pin is smeared
with Prussian blue pigment which is spread evenly over
the entire surface. The bearings are then clamped to-
gether in the usual manner with the proper bolts, and the
crank-shaft revolved several times to indicate the high
spots on the bearing cap. At the start of the process of
scraping in, the bearing may seat only at a few points as
shown at Fig. 187, G. Continued scraping will bring the
bearing surface as indicated at H, which r is a consider-
able improvement, while the process may be considered
complete when the brass indicates a bearing all over as
at I. The high spots are indicated by blue, as where the
shaft does not bear on the bearing there is no color.
The high spots are removed by means of a scraping tool
of the form shown at Fig. 187, F, which is easily made
from a worn-out file. These are forged to shape and
ground hollow as indicated in the section, and are kept
properly sharpened by frequent rubbing on an ordinary
oil stone. To scrape properly, the edge of the scraper
must be very keen. The straight and curved half-round
scrapers, shown at M and N, are used for bearings. The

Refitting Engine Bearings 447

three-cornered scraper, outlined at 0, is also used on
curved surfaces, and is of value in rounding off the sharp
corners. The straight or curved half-round type works
well on soft-bearing metals, such as babbitt, or white brass,
but on yellow brass or bronze it cuts very slowly, and as
soon as the edge becomes dull considerable pressure is
needed to remove any metal, this calling for frequent
sharpening.

When correcting errors on flat or curved surfaces by
hand- scraping, it is desirable, of course, to obtain an
evenly spotted bearing with as little scraping as possible.
When the part to be scraped is first applied to the sur-
face-plate, or to a journal in the case of a bearing, three
or four "high" spots may be indicated by the marking
material. The time required to reduce these high spots
and obtain a bearing that is distributed over the entire
surface depends largely upon the way the scraping is
started. If the first bearing marks indicate a decided
rise in the surface, much time can be saved -by scraping
larger areas than are covered by the bearing marks; this
is especially true of large shaft and engine bearings, etc.
An experienced workman will not only remove the heavy
marks, but also reduce a larger area ; then, when the
bearing is tested again, the marks will generally be dis-
tributed somewhat.' If the heavy marks which usually
appear at first are simply removed by light scraping,
these "point bearings" are gradually enlarged, but a
much longer time will be required to distribute them.

The number of times the bearing must be applied to
the journal for testing is important, especially when the
box or bearing is large and not easily handled. The time
required to distribute the bearing marks evenly depends
largely upon one's judgment in "reading" these marks.
In the early stages of the scraping operation, the marks
should be used partly as a guide for showing the high
areas, and instead of merely scraping the marked spot
the surface surrounding it should also be reduced, unless
it is evident that the unevenness is local. The idea should

448 Aviation Engines

be to obtain first a few large but generally distributed
marks; then an evenly and finely spotted surface can be
produced quite easily.

In fitting brasses when these are of .the removable
type, two methods may be used. The upper half of the
engine base may be inverted on a suitable bench or stand
and the boxes fitted by placing the crank-shaft in position,
clamping down one bearing cap at a time and fitting each
bearing in succession until they bed equally. From that
time on the bearings should be fitted at the same time
so the shaft will be parallel with the bottom of the cylin-
ders. Considerable time and handling of the heavy crank-
shaft may be saved if a preliminary fitting of the bearing
brasses is made by clamping them together with a car-
penter ? s wood clamp as shown at Fig. 187, J, and leaving
the crank-shaft attached to the bench as shown at C.
The brasses are revolved around the crank-shaft journal
and are scraped to fit wherever high spots are indicated
until they begin to seat fairly. When the brasses assume
a finished appearance the final scraping should be carried
on with all bearings in place and revolving the crank-
shaft to determine the area of the seating. When the
brasses are properly fitted they will not only show a full
bearing surface, but the shaft will not turn unduly hard
if revolved with a moderate amount of leverage.

Bearings of white metal or babbitt can be fitted tighter
than those of bronze, and care must be observed in sup-
plying lubricant as considerably more than the usual
amount is needed until the bearings are run in by several
hours of test block work. Before the scraping process
is started it is well to chisel an oil groove in the bearing
as shown at Fig. 187, L. Grooves are very helpful in
insuring uniform distribution of oil over the entire width
of bearing and at the same time act as reservoirs to retain
a supply of oil. The tool used is a round-nosed chisel,
the effort being made to cut the grooves of uniform
depth and having smooth sides. Care should be taken
not to cut the grooves too deeply, as this will seriously

' Fitting Connecting Rods 449

reduce the strength of the bearing bushing. The shape
of the groove ordinarily provided is clearly shown at
Fig. 187, Gr, and it will be observed that the grooves do
not extend clear to the edge of the bearing, but stop about
a quarter of an inch from that point. The hole through
which the oil is supplied to the bearing is usually drilled
in such a way that it will communicate with the groove.

The tool shown at Fig. 187, K, is of recent develop-
ment, and is known as a "crank-shaft equalizer." This
is a hand-operated turning tool, carrying cutters which are
intended to smooth down scored crank-pins without using
a lathe. The feed may be adjusted by suitable screws
and the device may be fitted to crank-pins and shaft -
journals of different diameters by other adjusting screws.
This device is not hard to operate, being merely clamped
around the crank- shaft in the same manner as the lapping
tool previously described, and after it has been properly
adjusted it is turned around by the levers provided for
the purpose, the continuous rotary motion removing the
metal just as a lathe tool would.

FITTING CONNECTING EODS

In the marine type rod, which is the form generally
used in airplane engines, one or two bolts are employed
at each side and the cap must be removed entirely before
the bearing can be taken off of the crank-pin. The tight-
ness of the brasses around the crank-pin can never be
determined solely by the adjustment of the bolts, as while
it is important that these should be drawn up as tightly
as possible, the bearing should fit the shaft without undue
binding, even if the brasses must be scraped to insure
a proper fit. As is true of the main bearings, the marine
form of connecting rod in some engines has a number of
liners or shims interposed between the top and lower
portions of the rod end, and these may be reduced in
number when necessary to bring the brasses closer to-
gether. The general tendency in airplane engines is to

450

Aviation Engines

eliminate shims in either the main or connecting rod bear-
ings, and when wear is noticed the boxes or liners are
removed and new ones supplied. The brasses are held
in the connecting rod and cap by brass rivets and are
generally attached in the main bearing by small brass
machine screws. The form of box generally favored is
a brass sand casting rich in copper to secure good heat
conductivity which forms a backing for a thin layer of
white brass, babbitt or similar anti-friction metal.

In fitting new brasses there are two conditions to be
avoided, these being outlined at Fig. 188, B and C. In

Retaining Bolts
A

"Retaining Bolts- :

Retaining Bolts-
C

Fig. 188. Showing Points to Observe When Fitting Connecting Bod

Brasses.

the case shown at C the light edges of the bushings are
in contact, but the connecting rod and its cap do not meet.
When the retaining nuts are tightened the entire strain
is taken on the comparatively small area of the edges of
the bushings which are not strong enough to withstand
the strains existing and which flatten out quickly, per-
mitting the bearing to run loose. In the example out-
lined at B the edges of the brasses do not touch when
the connecting rod cap is drawn in place. This is not
good practice, because the brasses soon become loose in
their retaining member. In the case outlined it is neces-

Testing Sprung Cam-shaft 451

sary to file off the faces of the rod and cap until these
meet, and to insure contact of the edges of the brasses
as well. In event of the brasses coming together before
the cap and rod make contact, as shown at C, the bearing
halves should be reduced at the edges until both the caps
and brasses meet against each other or the surfaces of
the liners as shown at A.

SPRUNG CAM-SHAFT

If the cam-shaft is sprung or twisted it will alter the
valve timing to such an extent that the smoothness of
operation of the engine will be materially affected. If
this condition is suspected the cam-shaft may be swung
on lathe centers and turned to see if it runs out and can
be straightened in any of the usual form of shaft-straight-
ening machines. The shaft may be twisted without being
sprung. This can only be determined by supporting one
end of the shaft in an index head and the other end on
a milling machine center. The cams are then checked to
see that they are separated by the proper degree of angu-
larity. This process is one that requires a thorough
knowledge of the valve timing of the engine in question,
and is best done at the factory where the engine was
made. The timing gears should also be examined to see
if the teeth are worn enough so that considerable back
lash or lost motion exists between them. This is espe-
cially important where worm or spiral gears are used.
A worn timing gear not only produces noise, but it will
cause the time of opening and closing of the engine valves
to vary materially.

PRECAUTIONS IN REASSEMBLING PARTS

When all of the essential components of a power plant
have been carefully looked over and cleaned and all de-
fects eliminated, either by adjustment or replacement of
worn portions, the motor should be reassembled, taking

452 Aviation Engines

care to have the parts occupy just the same relative posi-
tions they did before the motor was dismantled. As each
part is added to the assemblage care should be taken to
insure adequate lubrication of all new points of bearing
by squirting liberal quantities of cylinder oil upon them
with a hand oil can or syringe provided for the purpose.
In adjusting the crank-shaft bearings, tighten them one
at a time and revolve the shafts each time one of the
bearing caps is set up to insure that the newly adjusted
bearing does not have undue friction. All retaining keys
and pins must be positively placed and it is good practice
to cover such a part with lubricant before replacing it
because it will not only drive in easier, but the part may
be removed more easily if necessary at some future time.
If not oiled, rust collects around it.

"When a piece is held by more than one bolt or screw,
especially if it is a casting of brittle material such as
cast iron or aluminum, the fastening bolts should be tight-
ened uniformly. If one bolt is tightened more than the
rest it is liable to spring the casting enough to break it.
Spring washers, check nuts, split pins or other locking
means should always be provided, especially on parts
which are in motion or subjected to heavy loads.

Before placing the cylinder over the piston it is im-
perative that the slots in the piston rings are spaced
equidistant and that the piston is copiously oiled before
the cylinder is slipped over it. "When reassembling the
inlet and exhaust manifolds it is well to use only perfect
packings or gaskets and to avoid the use of those that
seem to have hardened up or flattened out too much in
service. If it is necessary to use new gaskets it is im-
perative to employ these at all joints on a manifold, be-
cause if old and new gaskets are used together the new
ones are apt to keep the manifold from bedding properly
upon the used ones. It is well to coat the threads of all
bolts and screws subjected to heat, such as cylinder head
and exhaust manifold retaining bolts, with a mixture of
graphite and oil. Those that enter the water jacket should

Reassembling Parts 453

be covered with white or red lead or pipe thread com-
pound. Gaskets will hold better if coated with shellac
before the manifold or other parts are placed over them.
The shellac fills any irregularities in the joint and assists
materially in preventing leakage after the joint is made
up and the coating has a chance to set.

Before assembling on the shaft, it is necessary to fit
the bearings by scraping, the same instructions given for
restoring the contour of the main bearings applying just
as well in this case. It is apparent that if the crank-pins
are not round no amount of scraping will insure a true
bearing. A point to observe is to make sure that the
heads of the bolts are imbedded solidly in their proper
position, and that they are not raised by any burrs or
particles of dirt under the head which will flatten out
after the engine has been run for a time and allow the
bolts to slack off. Similarly, care should be taken that
there is no foreign matter under the brasses and the
box in which they seat. To guard against this the bolts
should be struck with a hammer several times after they
are tightened up, and the connecting rod can be hit
sharply several times under the cap with a wooden mallet
or lead hammer. It is important to pin the brasses in
place to prevent movement, as lubrication may be inter-
fered with if the bushing turns round and breaks the cor-
rect register between the oil hole in the cap and brasses.

Care should be taken in screwing on the retaining nuts
to insure that they will remain in place and not slack off.
Spring washers should not be used on either connecting
rod ends or main bearing nuts, because these sometimes
snap in two pieces and leave the nut slack. The best
method of locking is to use well-fitting split pins and
castellated nuts.

TESTING BEARING PARALLELISM

It is not possible to give other than general directions
regarding the proper degree of tightening for a con-
necting rod bearing, but as a guide to correct adjustment

454 Aviation Engines

it may be said that if the connecting rod cap is tightened
sufficiently so the connecting rod will just about fall over
from a vertical position due to the piston weight when
the bolts are fully tightened up, the adjustment will be
nearly correct. As previously stated, babbitt or white
metal bearings can be set up more tightly than bronze,
as the metal is softer and any high spots will soon be
leveled down with the running of the engine. It is im-
portant that care be taken to preserve parallelism of
the wrist-pins and crank-shafts while scraping in bear-
ings. This can be determined in two ways. That shown
at Fig. 189, A, is used when the parts are not in the
engine assembly and when the connecting rod bearing is
being fitted to a mandrel or arbor the same size as the
crank-pin. The arbor, which is finished very smooth and
of uniform diameter, is placed in two V blocks, which in
turn are supported by a level surface plate. An ad-
justable height gauge may be tried, first at one side of
the wrist-pin which is placed at the upper end of the
connecting rod, then at the other, and any variation will
be easily determined by the degree of tilting of the rod.
This test may be made with the wrist-pin alone, or if
the piston is in place, a straight edge or spirit level may
be employed. The spirit level will readily show any in-
clination while the straight edge is used in connection
with the height gauge as indicated. Oi course, the sur-
face plate must be absolutely level when tests are made.
When the connecting rods are being fitted with the
crank-shaft in place in crank-case, and that member se-
cured in the frame, a steel square may be used as it is
reasonable to assume that the wrist-pin, and consequently
the piston, it carries, should observe a true relation with
the top of the engine base. If the piston side is at right
angles with the top of the engine base it is reasonable
to assume that the wrist-pin and crank-pin are parallel.
If the piston is canted to one side or the other, it will
indicate that the brasses have been scraped tapering,
which would mean considerable heating and undue .fric-

Testing Bearing Parallelism

455

tion if the piston is installed in the cylinder on account
of the pressure against one portion of the cylinder wall.
If the degree of canting is not too great, the connecting
rods may be sprung very slightly to straighten up the

Height

-Piston

Mandrel '

Mandrel*
V-Block

/-Straight Edge

......Connecting Rod

V- Block

Surface Plate--'"

.-Piston

> Cylinder Bed

'' Center Bearinq \ _
Front Bearing "End Bearing

Fig. 189. Methods of Testing to Insure Parallelism of Bearings After

Fitting.

piston, but this is a makeshift that is not advised. The
height gauge method shown above may be used instead
of the steel square, if desired, because the top of the
crank-case is planed or milled true and should be parallel
with the center line of the crank-shaft.

456 Aviation Engines

CAM-SHAFTS AND TIMING GEARS

Knocking sounds are also evident if the cam-shaft is
loose in its bearings, and also if the cams or timing
gears are loose on the shaft. The cam-shaft is usually
supported by solid bearings of the removable bushing
type, having no compensation for depreciation. If these
bearings wear the only remedy is replacement with new
ones. In the older makes of cars it was general practice
to machine the cams separately and to secure these to the
cam-shaft by means of taper pins or keys. These mem-
bers sometimes loosened and caused noise. In the event
of the cams being loose, care should be taken to use new
keys or taper pins, as the case may be. If the fastening
used was a pin, the hole through the cam-shaft will
invariably be slightly oval from wear. In order to insure
a tight job, the holes in cam and shaft must be reamed
with the next larger size of standard taper reamer and
a larger pin driven in. Another point to watch is the
method of retaining the cam-shaft gear in place. On
some engines the gear is fastened to a flange on the
cam-shaft by retaining screws. These are not apt to
become loose, but where reliance is placed on a key the
cam-shaft gear may often be loose on its supporting
member. The only remedy is to enlarge the key slot
in both gear and shaft and to fit a larger retaining key.

CHAPTER XII

Aviation Engine Types Division in Classes Anzani Engines Canton
and Unne Engine Construction of Gnome Engines "Monosou-
pape" Gnome German "Gnome" Type Le Rhone Engine
Renault Air-Cooled Engine Simplex Model "A" Hispana-Suiza
Curtiss Aviation Motors Thomas-Morse Model 88 Engine
Duesenberg Engine Aeromarine Six-Cylinder Wisconsin Avia-
tion Engines Hall-Scott Engines Mercedes Motor Benz Motor
Austro-Daimler Sunbeam-Coatalen.

AVIATION ENGINE TYPES

Inasmuch as numerous forms of airplane engines have
been devised, it would require a volume of considerable
size to describe even the most important developments
of recent years. As considerable explanatory matter has
been given in preceding chapters and the principles in-
volved in internal combustion engine operation consid-
ered in detail, a relatively brief review of the features
of some of the most successful airplane motors should
suffice to give the reader a complete enough understand-
ing of the art so all types of engines can be readily
recognized and the advantages and disadvantages of each
type understood, as well as defining the constructional
features enough so the methods of locating and repair-
ing the common engine and auxiliary system troubles
will be fully grasped..

Aviation engines can be divided into three main
classes. One of the earliest attempts to devise distinctive
power plant designs for aircraft involved the construc-
tion of engines utilizing a radial, arrangement of the
cylinders or a star-wise disposition. Among the engines
of this class may be mentioned the Anzani, B. E. P. and
the Salmson or Canton and Unne forms. The two former
are air-cooled, the latter design is water-cooled. Engines

457

458 Aviation Engines

of this type have been built in cylinder numbers ranging
from three to twenty. While the simple forms were
popular in the early days of aviation engine develop-
ment, they have been succeeded by the more conventional
arrangements which now form the largest class. The
reason for the adoption of a star-wise arrangement of
cylinders has been previously considered. Smoothness
of running can only be obtained by using a considerable
number of cylinders. . The fundamental reason for the
adoption of the star-wise disposition is that a better dis-
tribution of stress is obtained by having all of the pistons
acting on the same crank-pin so that the crank-throw and
pin are continuously under maximum stress. Some diffi-
culty has been experienced in lubricating the lower cylin-
ders in some forms of six cylinder, rotary crank, radial
engines but these have been largely overcome so they are
not as serious in practice as a theoretical consideration
would indicate.

Another class of engines developed to meet aviation
requirements is a complete departure from the preceding
class, though when the engines are at rest, it is difficult
to differentiate between them. This class includes en-
gines having a star-wise disposition of the cylinders but
the cylinders themselves and the crank-case rotate and
the crank-shaft remains stationary. The important rotary,
engine^ are the Gnome, the Le Ehone and the Clerget.
By far the most important classification is that includ-
ing engines which retain the approved design of the
types of power plants that have been so widely utilized
in automobiles and which have but slight modifications
to increase reliability and mechanical strength and pro-
duce a reduction in weight. This class includes the
vertical engines such as the Duesenberg and Hall-Scott
four-cylinder; the Wisconsin, Aeromarine, Mercedes,
Benz, and Hall-Scott six-cylinder vertical engines and
the numerous eight- and twelve-cylinder Vee designs such
as the Curtiss, Renault, Thomas-Morse, Sturtevant, Sun-
beam, and others.

Anzani Air-Cooled 'Engines 459

ANZANI ENGINES

The attention of the mechanical world was first di-
rected to the great possibilities of mechanical flight when
Bleriot crossed the English Channel in July, 1909, in a
monoplane of his own design and construction, having
the power furnished by a small three-cylinder air-cooled
engine rated at about 24 horse-power and having cylin-
ders 4.13 inches bore and 5.12 inches stroke, stated to
develop the power at about 1600 R.P.M. and weighing 145
pounds. The arrangement of this early Anzani engine is
shown at Fig. 190, and it will be apparent that in 'the
main, the lines worked out in motorcycle practice were
followed to a large extent. The crank-case was of the
usual vertically divided pattern, the cylinders and heads
being cast in one piece and held to the crank-case by
stud bolts passing through substantial flanges at the
cylinder base. In order to utilize but a single crank-pin
for the three cylinders it was necessary to use two forked
rods and one rod of the conventional type. The arrange-
ment shown at Fig. 190, called for the use of counter-
balanced flywheels which were built up in connection
with shafts and a crank-pin to form what corresponds to
the usual crank-shaft assembly.

The inlet valves were of the automatic type so that a
very simple valve mechanism consisting only of the ex-
haust valve push rods was provided. One of the diffi-
culties of this arrangement of cylinders was that the
impulses are not evenly spaced. For instance, in the
forms where the cylinders were placed 60 degrees apart
the space between the firing of the first cylinder and that
next in order was 120 degrees crank- shaft rotation, after
which there was an interval of 300 degrees before the
last cylinder to fire delivered its power stroke. In order
to increase the power given by the simple three-cylinder
air-cooled engine a six-cylinder water-cooled type, as
shown at Figs. 191 and 192, was devised. This was prac-
tically the same in action as the three-cylinder except

460

Aviation Engines

o
O

faJO

I
I

A.G.HAGSTROM N.Y.

Fig. 190a. Illustrations Depicting Wrong and Eight Methods of "Swing-
ing the Stick" to Start Airplane Engine. At Top, Poor Position to
Get Full Throw and Get Out of the Way. Below, Correct Position
to Get Quick Turn Over of Crank-Shaft and Spring Away from
Propeller.

461

462

Aviation Engines

that a double throw crank-shaft was used and while the
explosions were not evenly spaced the number of explo-
sions obtained resulted in fairly uniform application of
power.

The latest design of three-cylinder Anzani engine,
which is used to some extent for school machines, is
shown at Fig. 193. In this, the three-cylinders are sym-

Fig. 191. The Anzani Six-Cylinder Water-Cooled Aviation Engine.

metrically arranged about the crank-case or 120 degrees
apart. The balance is greatly improved by this arrange-
ment and the power strokes occur at equal intervals of
240 degrees of crank-shaft rotation. This method of con-
struction is known as the Y design. By grouping two of
these engines together, as outlined at Fig. 194, which
gives an internal view, and at Fig. 195, which shows the
sectional view, and using the ordinary form of double
throw crank-shaft with crank-pins separated by 180 de-
grees, a six-cylinder radial engine is produced which runs

Anzani Aviation Engines

463

very quietly and furnishes a steady output of power.
The peculiarity of the construction of this engine is in
the method of grouping the connecting rod about the
common crank-pin without using forked rods or the
"Mother rod" system employed in the Gnome engines.
In the Anzani the method followed is to provide each

, Cool ing Water
Outlets

.Water Jacket

Water
Outlet

'* Exhaust
ValvQ

Connecting-' . XN| .

Rods. A^\\ A'

Crank-Shaft"''

Crank Case--'

'Cylinder

^-Flywheel

Fig. 192. Sectional View of Anzani Six-Cylinder Water-Cooled Aviation

Engine.

connecting rod big end with a shoe which consists of a
portion of a hollow cylinder held against the crank-pin
by split clamping rings. The dimensions of these shoes
are so proportioned that the two adjacent connecting rods
of a group of three will not come into contact even when
the connecting rods are at the minimum relative angle.
The three shoes of each group rest upon a bronze sleeve
which is in halves and which surrounds the crank-pin

464

Aviation Engines

and rotates relatively to it once in each crank-shaft revo-
lution. The collars, which are of tough bronze, resist the
inertia forces while the direct pressure of the explosions
is transmitted directly to the crank-pin bushing by the
shoes at the big end of the connecting rod. The same

Valve
Operating Rod

Intake Pipe u- ,_ ^~[=

/Cylinder No. I

< Cylinder hold
down Bolts

Cylinder No. 3-

Carburetor--'

.G.HAGSTROM N.Y

Fig. 193. Three-Cylinder Anzani Air-Cooled Y-Form Engine.

method of construction, modified to some extent, is used
in the LeKhone rotary cylinder engine.

Both cylinders and pistons of the Anzani engines are
of cast iron, the cylinders being provided with a liberal
number of cooling flanges which are cast integrally. A
series of auxiliary exhaust ports is drilled near the base

Anzani Engine Construction

465

of each cylinder so that a portion of the exhaust gases
will flow out of the cylinder when the piston reaches the
end of its power stroke. This reduces the temperature
of the gases passing around the exhaust valves and pre-

,'Valve

Exhaust

Elbow-...

Induction Pipe

Cylinder hold
down Bolts --

Valve Rocker

^Valve Lift Rod

Carburetor

A.G.HAGSTROM N.Y.

Fig. 194. Anzani Fixed Crank-Case Engine of the Six-Cylinder Form
Utilizes Air Cooling Successfully.

vents warping of these members. Another distinctive
feature of this engine design is the method of attaching
the Zenith carburetor to an annular chamber surrounding
the rear portion of the crank-case from which the intake
pipes leading to the intake valves radiate. The magneto

466

Aviation Engines

is the usual six-cylinder form having the armature geared
to revolve at one and one-half times crank- shaft speed. .

The Anzani aviation engines are also made in ten-
and twenty-cylinder forms as shown at Fig. 196. It will

Propeller^

Exhaust Valve Rocker.

-Exhaust Valve, Push Rod

Section PC showing
Construction of
Connecting Rod
Big Ends

'Magneto
Magneto Drive Gear

-Intake Gas Passage
..-Carburetor

"" 'Primary flir Intake

'~~~ Fuel Pipe
Cooled Cylinder

Fig. 195. Sectional View Showing Internal Parts of Six-Cylinder Anzani
Engine, with Starwise Disposition of Cylinders.

467

468

Aviation Engines

be apparent that in the ten-cylinder form explosions will
occur every 72 degrees of crank-shaft rotation, while in
the twenty-cylinder, 200 horse-power engine at any in-

Fig. 197. Application of R. E. P. Five-Cylinder Fan-Shape Air-Cooled
Motor to Early Monoplane.

stant five of the cylinders are always working and ex-
plosions are occurring every 36 degrees of crank-shaft
rotation. On the twenty-cylinder engine, two carburetors

Canton and Unne Engine 469

are used and two magnetos, which are driven at two and
one-half times crank-shaft speed. The general cylinder
and valve construction is practically the same, as in the
simpler engines.

CANTON AND UNNE ENGINE

This engine, which has been devised specially for
aviation service, is generally known as the "Salmson"
and is manufactured in both France and Great Britain.
It is a nine-cylinder water-cooled radial engine, the nine-
cylinders being symmetrically disposed around the crank-
shaft while the nine connecting rods all operate on a
comman crank-pin in somewhat the same manner as the
rods in the Gnome motor. The crank-shaft of the Salm-
son engine is not a fixed one and inasmuch as the cylin-
ders do not rotate about the crank-shaft it is necessary
for that member to revolve as in the conventional engine.
The stout hollow steel crank-shaft is in two pieces and
has a single throw. The crank-shaft is built up some-
what the same as that of the Gnome engine. Ball bear-
ings are used throughout this engine as will be evident
by inspecting the sectional view given at Fig. 199. The
nine steel connecting rods are machined all over and are
fitted at each end with bronze bushings, the distance
between the bearing centers being about 3.25 times crank
length. The method of connecting up the rods to the
crank-pin is one of the characteristic features of this
design. No "mother" rod as supplied in the Gnome
engine is used in this type inasmuch as the steel' cage or
connecting rod carrier is fitted with symmetrically dis-
posed big end retaining pins. Inasmuch as the carrier
is mounted on ball bearings some means must be pro-
vided of regulating the motion of the carrier as if no
means were provided the resulting motion of the pistons
would be irregular.

The method by which the piston strokes are made to
occur at precise intervals involves a somewhat lengthy
and detailed technical explanation. It is sufficient to say

470

Aviation Engines

that an epicyclic train of gears, one of which is rigidly
attached to the crank-case so it cannot rotate is used,
while other gears make a connection between the fixed
gear and with another gear which is exactly the same

Fig. 198. The Canton and Unne Nine-Cylinder Water-Cooled Radial

Engine.

size as the fixed gear attached to the crank-case and which
is formed integrally with the connecting rod carrier. The
action of the gearing is such that the cage carrying the
big end retaining pins does not rotate independently of

Canton and Unne Engine

471

the crank-shaft, though, of course, the crank-shaft or
rather crank-pin bearings must turn inside of the big
end carrier cage.

Cylinders of this engine are of nickel steel machined
all over and carry water-jackets of spun copper which
are attached to the cylinders by brazing. The water

Rocker Lever---

Valve Ro eker Support

Valve Stem

How One Cam
Operates Two Valves

Intermediate
Planetary Pinions.--^

-^Radial Ball
Bearings

sembly Drive Gear

Non-Rotating
Crank Case

--Equalizing
' Gear "
Train

--Fixed
Equalizing
Gear

\?o to ry
CrankShaft

'Cam Drive Gear

Crank Shaft Bearings

Fig. 199. Sectional View Showing Construction of Canton and Unne
Water-Cooled Radial Cylinder Engine.

jackets are corrugated to permit the cylinder to expand
freely. The ignition is similar to that of the fixed crank
rotating cylinder engine. An ordinary magneto of the
two spark type driven at 1% times crank-shaft speed is
sufficient to ignite the seven-cylinder form, while in the

472 Aviation Engines

nine-cylinder engines the ignition magneto is of the
"shield" type giving four sparks per revolution. The
magneto is driven at 1% times crank-shaft speed. Nickel
steel valves are used and are carried in castings or cages
which screw into bosses in the cylinder head. Each
valve is cam operated through a tappet, push rod and
rocker arm, seven cams being used on a seven-cylinder
engine and nine cams on the nine-cylinder. One cam
serves to open both valves as in its rotation it lifts the
tappets in succession and so operates the exhaust and
inlet valves respectively. This method of operation in-
volves the same period of intake and exhaust. In nor-
mal engine practice the inlet valve opens 12 degrees
late and closes 20 degrees late. The exhaust opens
45 degrees early and closes 6 degrees late. This means
about 188 degrees in the case of inlet valve and 231 de-
grees crank-shaft travel for exhaust valves. In the
Salmson engine, the exhaust closes and the inlet opens at
the outer dead center and the exhaust opens and the inlet
closes at about the inner dead center. This engine is
also made in a fourteen-cylinder 200 B. H. P. design
which is composed of two groups of seven-cylinders, and
it has been made in an eighteen-cylinder design of 600
horse-power. The nine-cylinder 130 horse-power has a
cylinder bore of 4.73 inches and a stroke of 5.52 inches.
Its normal speed of rotation is 1250 E. P. M. Owing to
the radial arrangement of the cylinders, the weight is but
pounds per B. H. P.

CONSTRUCTION OF EARLY GNOME MOTOR

9'- , -

It cannot be denied that for a time one of the most
widely used of aeroplane motors was the seven-cylinder
revolving air-cooled Gnome, made in France. For a total
weight of 167 pounds this motor developed 45 to 47 horse-
power at 1,000 revolutions, being equal to 3.35 pounds
per horse-power, and has proved its reliability by securing
many long-distance and endurance records. The same

473

474 Aviation Engines

engineers have produced a nine-cylinder and by combi-
ning two single engines a four teen-cylinder revolving
Gnome, having a nominal rating of 100 horse-power, with
which world's speed records were broken. A still more
powerful engine has been made with eighteen-cylinders.
The nine-cylinder "monosoupape" delivers 100 horse-
power at 1200 K. P. M., the engine of double that number
of cylinders is rated at about 180 horse-power.

Except in the number of cylinders and a few mechani-
cal details the fourteen-cylinder motor is identical with
the seven-cylinder one; fully three-quarters of the parts
used by the assemblers would do just as well for one
motor as for the other. Owing to the greater power de-
mands of the modern airplane the smaller sizes of Gnome
engines are not used as much as they were except for
school machines. There is very little in this motor that
is common to the standard type of vertical motorcar
engine. The cylinders are mounted radially round a cir-
cular crank-case; the crank-shaft is fixed, and the entire
mass of cylinders and crank-case revolves around it as
outlined at Fig. 200.' The explosive mixture and the
lubricating oil are admitted through the fixed hollow
crank-shaft, passed into the explosion chamber through
an automatic intake valve in the piston head in the early
pattern, and the spent gases exhausted through a me-
chanically operated valve in the cylinder head. The
course of the gases is practically a radial one. A pecu-
liarity of the construction of the motor is that nickel steel
is used throughout. Aluminum is employed for the two
oil pump housings; the single compression ring known
as the "obdurator" for each piston is made of brass;
there are three or four brass bushes; gun metal is em-
ployed for certain pins the rest is machined out of
chrome nickel steel. The crank-case is practically a steel
hoop, the depth depending on whether it has to receive
seven- or f ourteen-cylinders ; it has seven or fourteen
holes bored as illustrated on its circumference. When
fourteen or eighteen cylinders are used the holes are

Gnome Engine Details 475

bored in two distinct planes, and offset in relation one to
the other.

The cylinders of the small engine which have a bore
of 4%o inches and a stroke of 4% inches, are machined
out of the solid bar of steel until the thickness of the walls
is only 1.5 millimeters .05905 inch, or practically % 6 inch.
Each one has twenty-two fins which gradually taper down
as the region of greatest pressure is departed from. In
addition to carrying away heat, the fins assist in strength-
ening the walls of the cylinder. The barrel of the cylin-
der is slipped into the hole bored for it on the circum-
ference of the crank-case and secured by a locking member
in the nature of a stout compression ring, sprung onto a
groove on the base of the cylinder within the crank cham-
ber. On each lateral face of the crank chamber are seven
holes, drilled right through the chamber parallel with the
crank-shaft. Each one of these holes receives a stout
locking-pin of such a diameter that it presses against
the split rings of two adjacent cylinders; in addition
each cylinder is fitted with a key- way. This construction
is not always followed, some of the early Gnome engines
using the same system of cylinder retention as used on
the latest "monosoupape" pattern.

The exhaust valve is mounted in the cylinder head,
Fig. 201, its seating being screwed in by means of a
special box spanner. On the fourteen-cylinder model the
valve is operated directly by an overhead rocker arm
with a gun metal rocker at its extremity coming in con-
tact with the extremity of the valve stem. As in standard
motor car practice, the valve is opened under the lift of
the vertical push rod, actuated by the cam. The distinc-
tive feature is the use of a four-blade leaf spring with
a forked end encircling the valve stems and pressing
against a collar on its extremity. On the seven-cylinder
model the movement is reversed, the valve being opened
on the downward pull of the push rod, this lifting the
outer extremity of the main rocker arm, w r hich tips a
secondary and smaller rocker arm in direct contact with

476

Aviation Engines

the extremity of the valve stem. The springs are the
same in each case. The two types are compared at A
and B, Fig. 202.

Exhaust Valve Spring,

..-- Valve Depressing
Rocker

.Exhaust Valve

Spark
'Plug

^.-Cooling
Flanges

Exhaust Valve-'

Electrodes -~-
slnlet Valve

-Piston
Rings

yU.-* Cylinder

^ Valve Actuating Push Rod

Fig. 201. Sectional View of Early Type Gnome Cylinder and Piston
Showing Construction and Application of Inlet and Exhaust Valves.

The pistons, like the cylinders, are machined out of
the solid bar of nickel steel, and have a portion of their
wall cut away, so that the two adjacent ones will not
come together at the extremity of their stroke. The head

.5?

477

478 Aviation Engines

of the piston is slightly reduced in diameter and is pro-
vided with a groove into which is fitted a very light
L-section brass split ring; back of this ring and carried
within the groove is sprung a light steel compression
ring, serving to keep the brass ring in expansion. As
already mentioned, the intake valves are automatic, and
are mounted in the head of the piston as outlined at Fig.
202, C. The valve seating is in halves, the lower portion
being made to receive the wrist-pin and connecting rod,
and the upper portion, carrying the valve, being screwed
into it. The spring is composed of four flat blades, with
the hollowed stem of the automatic valve passing through
their center and their two extremities attached to small
levers calculated to give balance against centrifugal force.
The springs are naturally within the piston, and are lubri-
cated by splash from the crank chamber. They are of
a delicate construction, for it is necessary that they shall
be accurately balanced so as to have no tendency to fly
open under the action of centrifugal force. The intake
valve is withdrawn by the use of special tools through the
cylinder head, the exhaust valve being first dismounted.
The fourteen-cylinder motor shown at Fig. 203, has a
two-throw crank-shaft with the throws placed at 180 de-
grees, each one receiving seven connecting rods. The
parts are the same as for the seven-cylinder motor, the
larger one consisting of two groups placed side by side.
For each group of seven-cylinders there is one main con-
necting rod, together with six auxiliary rods. The main
connecting rod, which, like the others, is of H section, has
machined with it two L-section rings bored with six holes
51% degrees apart to take the six other connecting
rods. The cage of the main connecting rod carries two
ball races, one on either side, fitting onto the crank-pin
and receiving the thrust of the seven connecting rods.
The auxiliary connecting rods are secured in position in
each case by a hollow steel pin passing through the two
rings. It is evident that there is a slightly greater angu-
larity for the six shorter rods, known as auxiliary con-

Gnome Engine Details

479

480 Aviation Engines

necting rods, than for the longer main rods ; this does not
appear to have any influence on the running of the motor.

Coming to the manner in which the earliest design ex-
haust valves are operated on the old style motor, this at
first sight appears to be one of the most complicated
parts of the motor, probably because it is one in which
standard practice is most widely departed from. Within
the cylindrical casing bolted to the rear face of the crank-
case are seven, thin flat-faced steel rings, forming female
cams. Across a diameter of each ring is a pair of pro-
jecting rods fitting in brass guides and having their
extremities terminating in a knuckle eye receiving the
adjustable push rods operating the overhead rocker arms
of the exhaust valve. The guides are not all in the same
plane, the difference > being equal to the thickness of the
steel rings, the total thickness being practically 2 inches.
Within the female cams is a group of seven male cams
of the same total thickness as the former and rotating
within them. As the boss of the male cam comes into
contact with the flattened portion of the ring forming
the female cam, the arm is pushed outward and the ex-
haust valve opened through the medium of the push-rod
and overhead rocker. This construction was afterwards
changed to seven male cams and simple valve operating
plunger and roller cam followers as shown at Fig. 204.

On the face of the crank-case of the fourteen-cylinder
motor opposite to the valve mechanism is a bolted-on end
plate, carrying a pinion for driving the two magnetos
and the two oil pumps, and having bolted to it the dis-
tributor for the high-tension current. Each group of
seven-cylinders has its own magneto and lubricating
pump. The two magnetos and the two pumps are mounted
on the fixed platform carrying the stationary crank-shaft,
being driven by the pinion on the revolving crank cham-
ber. The magnetos are geared up in the proportion of
4 to 7. Mounted on the end plate back of the driving
pinion are the two high-tension distributor plates, each
one with seven brass segments let into it and connection

Gnome Engine Details

481

made to the plugs by means of plain brass wire. The
wire passes through a hole in the plug and is then
wrapped round itself, giving a loose connection.

Revolving Carri

Planetary

Pinions

Hon-
Rotative
Timing K
Gear

Ball
Bearing

-_ Valve' Actuating Tube

^1 ff -Valve Plunger Guide
^, f " Valve Plunger

Roller
Bearing

,'Fixed Crank-Shaft End

> Crank- Sh aft
Tie Bolt

Revolving Planetary
Pinions

** Planetary Pinion Stud

Cam Case Flange'

Fig. 204. Cam and Cam-Gear Case of the Gnome Seven-Cylinder
Revolving Engine.

482

Aviation Engines

A good many people doubtless wonder why rotary en-
gines are usually provided with an odd number of cylin-
ders in preference to an even number. It is a matter of
even torque, as can easily be understood from the accom-
panying diagram. Fig. 205, A, represents a six-cylinder
rotary engine, the radial lines indicating the cylinders.
It is possible to fire the charges in two ways, firstly, in
rotation, -1, 2, 3, 4, 5, 6, thus having six impulses in one
revolution and none in the next; or alternately, 1, 3, 5, 2,
4, 6, in which case the engine will have turned through

Fig. 205. Diagrams Showing Why An Odd Number of Cylinders is Best
for Eotary Cylinder Motors.

an equal number of degrees between impulses 1 and 3,
and 3 and 5, but a greater number between 5 and 2, even
again between 2 and 4, 4 and 6, and a less number be-
tween 6 and 1, as will be clearly seen on reference to the
diagram. Turning to Fig. 205, B, which represents a
seven-cylinder engine. If the cylinders fire alternately
it is obvious that the engine turns through an equal
number of degrees between each impulse, thus, 1, 3, 5, 7,
2, 4, 6, 1, 3, etc. Thus supposing the engine to be revolv-
ing, the explosion takes place as each alternate cylinder
passes, for instance, the point 1 on the diagram, and the
ignition is actually operated in this way by a single
contact.

Gnome Engine Details

483

The crank-shaft of the Gnome, as already explained,
is fixed and hollow. For the seven- and nine-cylinder
motors it has a single throw, and for the fourteen- and
eighteen-cylinder models has 'two throws at 180 degrees.
It is of the built-up type, this being necessary on account

/ThroHle Lever

.Crctnk-Shaft End

Tig. 206. Simple Carburetor Used On Early Gnome Engines Attached
to Fixed Crank-Shaft End.

of the distinctive mounting of the connecting rods. The
carburetor shown at Fig. 206 is mounted at one end of
. the stationary crank-shaft, and the mixture is drawn in
through a valve in the piston as already explained. There
is neither float chamber nor jet. In many of the tests
made at the factory it is said the motor will run with the
extremity of the gasoline pipe pushed into the hollow

484

Aviation Engines

crank-shaft, speed being regulated entirely by increasing
or decreasing the flow through the shut-off valve in the
base of the tank. Even under these conditions the motor
has been throttled down to 'run at 350 revolutions with-
out misfiring. Its normal speed is 1,000 to 1,200 revolu-
tions a minute. Castor oil is used for lubricating the
engine, the oil being injected into the hollow crank- shaft

.Ball Bearings^

Pump Drive Bear

Cam\,

.'Worm

''-Cam Shaft
Drive Worm
Gear

Pump
Cylinder"'

Pump Plunger''

'Plunger Return
Springs

Valve
Plunger

Oil Pipe

Fig. 207. Sectional Views of the Gnome Oil Pump.

through slight-feed fittings by a mechanically operated
pump which is clearly shown in sectional diagrams at
Fig. 207.

The Gnome is a considerable consumer of lubricant,
the makers' estimate being 7 pints an hour for the 100
horse-power motor; but in practice this is largely ex-
ceeded. The gasoline consumption is given as 300 to 350
grammes per horse-power. The total weight of the four-
teen-cylinder motor is 220 pounds without fuel or lubri-

Gnome Engine Details

485

eating oil. Its full power is developed at 1,200 revolu-
tions, and at this speed about 9 horse-power is lost in
overcoming air resistance to cylinder rotation.

While the Gnome engine has many advantages, on the
other hand, the head resistance offered by a motor of this

Current Supply Brush

.-Secondary Wire to Plug

Spark Plug

"Magneto
Collector Ring

Ma gnet-

Fig. 208. Simplified Diagram Showing Gnome Motor Magneto Ignition

System.

type is considerable ; there is a large waste of lubricating
oil due to the centrifugal force which tends to throw the
oil away from the cylinders; the gyroscopic effect of
the rotary motor is detrimental to the best working of the
aeroplane, and moreover it requires about seven per cent,
of the total power developed by the motor to drive the
revolving cylinders around the shaft. Of necessity, the

486 Aviation Engines

compression of this type of motor is rather low, and an
additional disadvantage manifests itself in the fact that
there is as yet no satisfactory way of muffling the rotary
type of motor.

GNOME "MONOSOUPAPE" TYPE

The latest type of Gnome engine is known as the
"monosoupape" type because but one valve is used in
the cylinder head, the inlet -valve in the piston being dis-
pensed with on account of the trouble caused by that
member on earlier engines. The construction of this
latest type follows the lines established in the earlier
designs to some extent and it differs only in the method
of charging. The very rich mixture of gas and air is
forced into the crank-case through the jet inside the
crank- shaft, and enters the cylinder when the piston is
at its lowest position, through the half-round openings
in the guiding flange and the small holes or ports ma-
chined in the cylinder and clearly shown at Fig. 210.
The returning piston covers the port, and the gas is com-
pressed and fired in the usual way. The exhaust is
through a large single valve in the cylinder head, which
gives rise to the name "monosoupape," or single-valve
motor, and this valve also remains open a portion of the
intake stroke to admit air into the cylinder and dilute
the rich gas forced in from the crank-case interior.
Aviators who have used the early form of Gnome say
that the inlet valve in the piston type was prone to catch
on fire if any valve defect materialized, but the "monosou-
pape" pattern is said to be nearly free of this danger.
The bore of the 100 horse-power nine-cylinder engine is
110 mm., the piston stroke 150 mm. Extremely careful
machine work and fitting is necessary. In many parts,
tolerances of less than .0004" (four ten thousandths of
an inch) are all that are allowed. This is about one-
sixth the thickness of the average human hair, and in
other parts the size must be absolutely standard, no
appreciable variation being allowable. The manufacture

Gnome Monosoupape Engine

487

of this engine establishes new mechanical standards of
engine production in this country. Much machine work
is needed in producing the finished components from the
bar and forging.

The cylinders, for example, are machined from 6 inch
solid steel bars, which are sawed into blanks 11 inches

Fig. 209. The G. V. Gnome "Monosoupape" Nine-Cylinder Eotary Engine
Mounted on Testing Stand.

in length and weighing about 97 pounds. The first opera-
tion is to drill a 2M.6 inch hole through the center of the
block. A heavy-duty drilling machine performs this

488

Aviation Engines

Gnome Monosoupape Engine 489

work, then the block goes to the lathe for further opera-
tions. Fig. 211 shows six stages of the progress of a
cylinder, a few of the intermediate steps being omitted.

Fig. 211. How a Gnome Cylinder is Reduced from Solid Chunk of Steel
Weighing 97 Pounds to Finished Cylinder Weighing 5y 2 Pounds.

These give, however, a good idea of the work done. The
turning of the gills, or cooling flanges, is a difficult propo-
sition, owing to the depth of the cut and the thin metal
that forms the gills. This operation requires the utmost
care of tools and the use of a good lubricant to prevent

490 Aviation Engines

the metal from tearing as the tools approach their full
depth. These gills are only 0.6 mm., or 0.0237 in., thick
at the top, tapering to a thickness of 1.4 mm. (0.0553 in.)
at the base, and are 16 mm. (0.632 in.) deep. When the
machine work is completed the cylinder weighs but 5%
pounds.

GNOME FUEL SYSTEM, IGNITION AND LUBRICATION

The following description of the fuel supply, ignition
and oiling of the "monosoupape," or single valve Gnome,
is taken from "The Automobile. "

Gasoline is fed to the engine by means of air pressure
at 5 pounds per sq. in., which is produced by the air
pump on the engine clearly shown at Fig. 210. A pres-
sure gauge convenient to the operator indicates this pres-
sure, and a valve enables the operator to control it. No
carburetor is used. The gasoline flows from the tank
through a shut-off valve near the operator and through
a tube leading through the hollow crank- shaft to a spray
nozzle located in the crank-case. There is no throttle
valve, and as each cylinder always receives the same
amount of air as long as the atmospheric pressure is the
same, the output cannot be varied by reducing the fuel
supply, except within narrow limits. A fuel capacity of
65 gallons is provided. The fuel consumption is at the
rate of 12 U. S. gallons per hour.

The high-tension magnetos, with double cam or two
break per revolution interrupter, is located on the thrust
plate in an inverted position, and is driven at such a
speed as to produce nine sparks for every two revolu-
tions; that is, at 2i/4 times engine speed. A Splitdorf
magneto is fitted. There is no distributor on the mag-
neto. The high-tension collector brush of the magneto
is connected to a distributor brush holder carried in the
bearer plate of the engine. The brush in this brush
holder is pressed against a distributor ring of insulating
material molded in position in the web of a gear wheel

Gnome Monosoupape Engine 491

keyed to the thrust plate, which gear serves also for
starting the engine by hand. Molded in this ring of in-
sulating material are nine brass contact sectors, connect-
ing with contact screws at the back side of the gear,
from which bare wires connect to the spark-plugs. The
distributor revolves at engine speed, instead of at half
engine speed as on ordinary engines, and the distributor
brush is brought into electrical connection with each

Fig. 212. The Gnome Engine Cam-Gear Case, a Fine Example of Accurate

Machine Work.

spark-plug every time the piston in the cylinder in which
this spark-plug is located approaches the outer dead
center. However, on the exhaust stroke no spark is being
generated in the magneto, hence none is produced at the
spark-plug.

Ordinarily the engine is started by turning on the
propeller, but for emergency purposes as in seaplanes or
for a quick "get away" if landing inadvertently in
enemy territory, a hand starting crank is provided. This
is supported in bearings secured to the pressed steel
carriers of the engine and is provided with a universal

492

Aviation Engines

joint between the two supports so as to prevent binding
of the crank in the bearings due to possible distortion
of the supports. The gear on this starting crank and the
one on the thrust plate with which it meshes are cut

Fig. 213. G. V. Gnome "Monospupape," with Cam-Case Cover Removed to
Show Cams and Valve-Operating Plungers with Roller Cam Followers.

with helical teeth of such hand that the starting pinion
is thrown out of mesh as soon as the engine picks up its
cycle. A coiled spring surrounds part of the shaft of the
starting crank and holds it out of gear when not in use.
Lubricating oil is carried in a tank of 25 gallon ca-
pacity, and if this tank has to be placed in a low position

German Gnome Type Engine 493

it is connected with the air-pressure line, so that the
suction of the oil pump is not depended upon to get the
oil to the pump. From the bottom of the oil tank a pipe
leads to the pump inlet. There are two outlets from the
pump, each entering the hollow crank-shaft, and there is
a branch from each outlet pipe to a circulation indicator
convenient to the operator. One of the oil leads feeds
to the housing in the thrust plate containing the two rear
ball bearings, and the other lead feeds through the crank-
pin to the cams, as already explained.

Owing to the effect of centrifugal force and the fact
that the oil is not used over again, the oil consumption
of a revolving cylinder engine; is considerably higher than
that of a stationary cylinder engine. Fuel consumption
is also somewhat higher, and for this reason the revolv-
ing cylinder engine is not so well suited for types of air-
planes designed for long trips, as the increased weight
of supplies required for such trips, as compared with
stationary cylinder type motors, more than offsets the
high weight efficiency of the engine itself. But for short
trips, and especially where high speed is required, as in
single seated scout and battle planes or "avious de
chasse," as the French say, the revolving cylinder engine
has the advantage. The oil consumption of the Gnome
engine is as high as 2.4 gallon per hour. Castor oil is
used for lubrication because it is not cut by the gasoline
mist present in the engine interior as an oil of mineral
derivation would be.

GEKMAN "QNOME" TYPE

A German adaptation of the Gnome design is shown
at Fig. 214. This is known as the Bayerischen Motoren
Gesellshaft engine and the type shown is an early design
rated at 50 horse-power. The bore is 110 mm., the stroke
is 120 mm., and it is designed to run at a speed of 1,200
K. P. M. It is somewhat similar in design to the early
Gnome "valve-in-piston" design except that two valves

494

Aviation Engines

bb
FH

Le Rhone Rotary Motor 495

are carried in the piston top instead of one. The valve
operating arrangement is different also, as a single four
point cam is used to operate the seven exhaust valves.
It is driven by epicyclic gearing, the cam being driven by
an internal gear machined integrally with it, the cam
being turned at % times the engine speed. Another
feature is the method of holding the cylinders on the
crank-case. The cylinder is provided with a flange that
registers with a corresponding member of the same diam-
eter on the crank-case. A U section, split clamping ring
is bolted in place as shown, this holding both flanges
firmly together and keeping the cylinder firmly seated
against the crank-case flange. The "monosoupape" type
has also been copied and has received some application
in Germany, but the most successful German airplanes
are powered with six-cylinder vertical engines such as
the Benz and Mercedes.

THE LE RHONE MOTOR

The Le Ehone motor is a radial revolving cylinder
engine that has many of the principles which are incor-
porated in the Gnome but which are considered to be an
improvement by many foreign aviators. Instead of having
but one valve in the cylinder head, as the latest type
"monosoupape" Gnome has, the Le Rhone has two valves,
one for intake and one for exhaust in each . cylinder. By
an ingenious rocker arm and tappet rod arrangement
it is possible to operate both valves with a single push
rod. Inlet pipes communicate with the crank-case at one
end and direct the fresh gas to the inlet valve cage at the
other. Another peculiarity in the design is the method
of holding the cylinders in place. Instead of having a
vertically divided crank-case as the Gnome engine has
and clamping both valves of the case around the cylin-
ders, the crank-case of the Le Rhone engine is in the
form of a cylinder having nine bosses provided with
threaded openings into which the cylinders are screwed.

496

Aviation Engines

A thread is provided at the base of each cylinder and
when the cylinder has been screwed down the proper
amount it is prevented from further rotation about its
own axis by a substantial lock nut which screws down

Fig. 215. Nine-Cylinder Revolving Le Rhone Type Aviation Engine.

against the threaded boss on the crank-case. The ex-
ternal appearance of the Le Ehone type motor is clearly
shown at Fig. 215, while the general features of con-
struction, are clearly outlined in the sectional views given
at Figs. 216 and 217.

497

498

Aviation Engines

The two main peculiarities of this motor are the
method of valve actuation by two large cams and the
distinctive crank-shaft and connecting rod big end con-
struction. The connecting rods are provided with "feet"
or shoes on the end which fit into grooves lined with
bearing metal which are machined into crank discs

Piston.
Cylinder

'--Ball Bearing RockerShaft
=. Valve Operating Rod

.-Operating Rod Plunger

f .~ Ignition Distributor

.-Current Supply Brush
Oil

< J

"Anchorage Plates-''

Fixed
Crank-Shaft-

Rotary Crank Case _._

~- Ball Bearing

Fig. 217. Side Sectional View of I*e Rhone Aviation Engine.

revolving on ball bearings and which are held together so
that the connecting rod big ends are sandwiched between
them by clamping screws. This construction is a modifi-
cation of that used on the Anzani six-cylinder radial
engine. There are three grooves machined in each crank
disc and three connecting rod big ends fun in each pair
of grooves. The details of this construction can be readily
ascertained by reference to explanatory diagrams at
Figs. 218 and 219, A. Three of the rods which work

Le Rhone Rotary Motor

499

in the groove nearest the crank-pin are provided with
short shoes as shown at Fig. 219, B. The short shoes
are used on the rods employed in cylinders number 1,
4, and 7. The set of connecting rods that work in the
central grooves are provided with medium-length shoes

-Piston

Valve
Rocker

Exhaust
Valve

Induction Pipe,

' r ' ^V t ,-'A ir Co o I in g Fla ngfes

Air Cooled /
Cylinder--'

Threads fo

hold Cylinder '

Crank Case'''

Connecting
Rod

..'Connecting Rod
and Crankshaft
Assembly

Valve liff Rods

Fig. 218. View Showing Le Rhone Valve Action and Connecting Rod
Big End Arrangement.

and actuate the pistons in cylinders numbers 3, 6, and 9.
The three rods that work in the outside grooves have still
longer shoes and are employed in cylinders numbers 2,
5, and 8. The peculiar profile of the inlet and exhaust
cam plates are shown at C, Fig. 219, while the construc-
tion of the wrist-pin, wrist-pin bushing and piston are
clearly outlined at the sectional view at E. The method

500

Aviation Engines

of valve actuation is clearly outlined at Fig. 220, which
shows an end section through the cam case and also
a partial side elevation showing one of the valve operating
levers which is fulcrumed at a central point and which

Short Rod End Feet Medium Rod End Feet

on #l-4-7

on*3-6-9

Diagram Showing Connecting
Rod Assembly

Lonq Rod End Feet

on*Z-5-8

Arrangement of Curved Bearingson
Connecting Rod Ends

i /- C

Piston ..

Wrist Pin.-'

Into ke Cam

Fig. 219. Diagrams Showing Important Components of Le Rhone Motor.

has a roller at one end bearing on one cam while the
roller or cam follower at the other end bears on the other
cam. The valve rocker arm actuating rod is, of course,
operated by this simple lever and is attached to it in
such a way that it can be pulled down to. depress the
inlet valve and pushed up to open the exhaust valve.

Le Rhone Engine D.etails

501

A carburetor of peculiar construction is employed in
the Le Khone engine, this being a very simple type as
outlined at Fig. 221. It is attached to the threaded end
of the hollow crank-shaft by a right and left coupling.

Rocker Shaft Actuator.^
Rocker'Shaff Bearing-''.'"",
Valve Rocker-"'

Exhaust Valve -^

Valve Actuating Rod -

Air Cooled

Cylinder--:

.Inlet-
Valve

Cam Drive Gear Internal

mmnX

Fixed
CrankShaft

Cam
Drive
Pinion-

Internal
Pinion

^Cam Plate Supporting
Ball Bearings

^'Internal Pinion
'Internal Gear

Fig. 220. How the Cams of the Le Rhone Motor Can Operate Two Valves
with a Single Push Bod.

502

Aviation Engines

The fuel is pumped to the spray nozzle, the opening in
which is controlled by a fuel regulating needle having
a long taper which is lifted out of the jet opening when
the air-regulating slide is moved. The amount of fuel
supplied the carburetor is controlled by a special needle
valve fitting which combines a filter screen and which is
shown at B. In regulating the speed of the Le Ehone

Slide Operating.
Link

Regulating Slide
Air Screen - x

Fuel Control
Bell Crank .._

Carburetor
.'Right and
; Left Coupling

-Needle Seating
Spring

.-Link

~' .- Valve Stem
'"' -.Stuffing-Box

\. ---Packing

'-Fuel Intake

' Fuel Feed

^Regulating
Needle

'Air Entrance

Fuel Entrance-

\ *Spray Nozzle

^Fuel Regulating
Needle

^"Filter Screen

Fig. 221. The Le Ehone Carburetor at A and Fuel Supply Regulating

Device at B.

engine, there are two possible means of controlling the
mixture, one by altering the position of the air-regulating
slide, which also works the metering needle in the jet, and
the other by controlling the amount of fuel supplied to
the spray nozzle through the special fitting provided for
that purpose.

In considering the action of this engine one can refer
to Fig. 222. The crank 0. M. is fixed, while the cylinders
can turn about the crank- shaft center and the piston

Le Rhone Engine Action

503

turns around the crank-pin M, because of the eccentricity
of the centers of rotation the piston will reciprocate in
the cylinders. This distance is at its maximum when
the cylinder is above and at a minimum when it is
above M, and the difference between these two positions
is equal to the stroke, which is twice the distance of the
crank-throw 0, M. The explosion pressure resolves itself
into the force F exerted along the line of the connecting
rod A, M, and also into a force N, which tends to make

Firing Order
1-3-5-7-9-2-4*6-8

Fig. 222. Diagrams Showing Le Rhone Motor Action and Firing Order.

the cylinders rotate around point in the direction of
the arrow. An odd number of cylinders acting on one
crank-pin is desirable to secure equally spaced explosions,
as the basic action is the same as the Gnome engine.

The magneto is driven by a gear having 36 teeth at-
tached to crank-case which meshes with 16-tooth pinion
on armature. The magneto turns at 2.25 times crank-
case speed. Two cams, one for inlet, one for exhaust,
are mounted on a carrying member and act on nine
rocker arms which are capable of giving a push-and-pull

504

Aviation Engines

motion to the valve-actuating rocker-operating rods. A
gear driven by the crank-case meshes with a larger mem-
ber having internal teeth carried by the cam carrier.
Each cam has five profiles and is mounted in staggered

Top Dead
Center

Bottom Dead
Center

Fig. 223. Diagram Showing Positions of Piston in Le Rhone Rotary

Cylinder Motor.

relation to the other. These give the nine fulcrumed
levers the proper motion to open the inlet and exhaust
valves at the proper time. The cams are driven at
4 %o or % of the motor speed. The cylinder dimensions
and timing follows; the weight can be approximated by
figuring 3 pounds per horse-power.

Renault Air-Cooled Vee Engine

505

80 H. P .105 M/M bore 4.20" bore.

140 M/M stroke 5.60" stroke.

110 H. P 112 M/M bore 4.48" bore.

170 M/M stroke 6.80" stroke.

Timing Intake valve opening, lag 18"^ 18 0> |

Intake valve closing, lag 35 35 I

Exhaust valve opening, lead 55 i-110 H. P. 45 ^80 H. P.

Exhaust valve closing, lag 5 | 5 I

Ignition time advance 26J 26J

THE RENAULT AIR-COOLED VEE ENGINE

Air-cooled stationary engines are rarely used in air-
planes, but the Eenault Freres of France have for several
years manufactured a complete series of such engines of
the general design shown at Fig. 225, ranging from a

Opening of Inlet Valve

Inlet Valve Closing

Igri it/on Point
C

Firing Order
1-3-5-7-9-2-4-6-8

Opening of Exhaust
D

Exhaust Voilve Closing

Fig. 22*. Diagrams Showing Valve Timing of Le Rhone Aviation Engine.

506

Aviation Engines

low-powered one developed eight or nine years ago and
rated at 40 and 50 horse-power, to later eight-cylinder

Blower Casing

- flir-coolect
' Cylinders

,-Hot Air Pipe
to Carburetor

Casing

'Supporting Tubes

Fig. 225. Diagrams Showing How Cylinder Cooling is Effected in
Renault Vee Engines.

models rated at 70 horse-power and a twelve-cylinder, or
twin six, rated at 90 horse-power. The cylinders are of
cast iron and are furnished with numerous cooling ribs

Renault Air-Cooled Vee Engine

507

which are cast integrally. The cylinder heads are sepa-
rate castings and are attached to the cylinder as in early
motorcycle engine practice, and serve to hold the cylinder
in place on the aluminum alloy crank-case by a cruciform
yoke and four long hold-down bolts (Fig. 226). The

,-Exhaust Valve Operating Rod

Exhaust Valve Eyhaus t

< Valve
.-Spring

Cylinder hold
down hluts-.

Cylinder

Hold down Bolts-**.;'''

Supporting Tube-''
Breather-

Spark Plugs*.,

Inlet Valve %.-

Valve Spring :

Crank Shaft

Oil Pump Drive Rod

Oil Strainer JL

Oil Pump

Fig. 226. End Sectional View of Renault Air-Cooled Aviation Engine.

pistons are of cast steel and utilize piston rings of cast
iron. The valves are situated on the inner side of the
cylinder head, the arrangement being unconventional in
that the exhaust valves are placed above the inlet. The
inlet valves seat in an extension of the combustion head
and are actuated by direct push rod and cam in the usual
manner while an overhead gear in which rockers are oper-

508 Aviation Engines

ated by push rods is needed to actuate the exhaust valves.
The valve action is clearly shown in Figs. 226 and 227.
The air stream "by which the cylinders are cooled is pro-
duced by a centrifugal or blower type fan of relatively
large diameter which is mounted on the end of a crank-
shaft and the air blast is delivered from this blower into
an enclosed space between the cylinder from which it
escapes only after passing over the cooling fins. In
spite of the fact that considerable prejudice exists against
air-cooling fixed cylinder engines, the Eenault has given
very good service in both England and France.

As will be seen by the sectional view at Fig. 227, the
steel crank-shaft is carried in a combination of plain
bearings inside the crank-case and by ball bearings at the
ends. Owing to air cooling, special precautions are taken
with the lubrication system, though the lubrication is not
forced or under high pressure. An oil pump of the gear-
.wheel type delivers oil from the sump at the bottom of the
crank-case to a chamber above, from which the oil flows
by gravity along suitable channels to the various main
bearings. It flows from the bearings into hollow rings
fastened to the crank-webs, and the oil thrown from the
whirling connecting rod big ends bathes the internal
parts in an oil mist. In the eight-cylinder designs igni-
tion is effected by a magneto giving four sparks per revo-
lution and is accordingly driven at engine speed. In the
twelve-cylinder machine two magnetos of the ordinary
revolving armature or two-spark type, each supplying
six cylinders, are fitted as outlined at Fig. 228. The
carburetor is a float feed form. Warm air is supplied
for Winter and damp weather by air pipes surrounding
the exhaust pipes. The normal speed of the Renault
engine is 1,800 R. P. M., but as the propeller is mounted
upon an extension of the cam-shaft the normal propeller
speed is but half that of the engine, which makes it pos-
sible to use a propeller of large diameter and high effi-
ciency. Owing to the air cooling, but low compression
may be used, this being about 60 pounds per square inch,

^09

510

Aviation Engines

which, of course, lowers the mean effective pressure and
makes the engine less efficient than water-cooled forms
where it is possible to use compression "pressure of 100

/ Magnetos
Magneto

/Distributor

Engine ^
Supporting 1
Tube

Crank Case Lower
half and Oil Sump

Oil Filler and
Breather Pipe

Fig. 228. End View of Renault Twelve-Cylinder Engine Crank-Case,
Showing Magneto Mounting.

511

512 Aviation Engines

or more pounds per square inch. The 70 horse-power
engine has cylinders with a bore of 3.78 inches and a
stroke of 5.52 inches. Its weight is given as 396 pounds,
when in running order, which figures 5.7 pounds per
horse-power. The same cylinder size is used on the
twelve-cylinder 100 horse-power and the stroke is the
same. This engine in running order weighs 638 pounds,
which figures approximately 6.4 pounds per B. H. P.

SIMPLEX MODEL. "A" HISPANO-STJIZA

The Model A is of the water-cooled four-cycle Vee
type, with eight cylinders, 4.7245 inch bore by 5.1182 inch
stroke, piston displacement 718 cubic inches. At sea-level
it develops 150 horse-power at 1,450 E. P. M. It can
be run successfully at much higher speeds, depending
on propeller design and gearing, developing proportion-
ately increased power. The weight, including carburetor,
two magnetos, propeller hub, starting magneto and crank,
but without radiator, water or oil or exhaust pipes, is
445 pounds. Average fuel consumption is .5 pound per
horse-power hour and the oil consumption at 1,450 E. P.
M. is three quarts per hour. The external appearance is
shown at Fig. 230.

Four cylinders are contained in each block, which is
of built-up construction; the water jackets and valve
ports are cast aluminum and the individual cylinders
heat-treated steel forgings threaded into the bored holes
of the aluminum castings. Each block after assembly is
given a number of protective coats of enamel, both inside
and out, baked on. Coats on the inside are applied
under pressure. The pistons are aluminum castings,
ribbed. Connecting rods are tubular, of the forked type.
One rod bears directly on the crank-pin; the other rod
has a bearing on the outside of the one first mentioned.

The crank-shaft is of the five-bearing type, very short,
stiff in design, bored for lightness and for the oiling
system. - The crank-shaft extension is tapered for the

His pano- Suiza Engine 513

French standard propeller hub, which is keyed and
locked to the shaft. This makes possible instant change
of propellers. The case is in two halves divided on the
center line of the crank-shaft, the bearings being fitted
between the upper and lower sections. The lower half
is deep, providing a large oil reservoir and stiffening
the engine. The upper half is simple and provides mag-
neto supports on extension ledges of the two main faces.
The valves are of large diameter with hollow stems,

Fig. 230. The Simplex Model A Hispano-Suiza Aviation Engine, a Very

Successful Form.

working in cast iron bushings. They are directly operated
by a single hollow cam-shaft located over the valves. The
cam-shafts are driven from the crank-shaft by vertical
shafts and bevel gears. The cam-shafts, cams and heads
of the valve stems are all enclosed in oil-tight removable
housings of cast aluminum.

Oiling is by a positive pressure system. The oil is
taken through a filter and steel tubes cast in the case
to main bearings, through crank-shaft to crank-pins.
The fourth main bearing is also provided with an oil
lead from the system and through tubes running up the
end of each cylinder block, oil is provided for the cam-

514 Aviation Engines

shafts, cams and bearings. The surplus oil escapes
through the end of the cam-shaft where the driving gears
are mounted, and with the oil that has gathered in the
top casing, descends through the drive shaft and gears
to the sump.

Ignition is by two eight-cylinder magnetos firing two
spark-plugs per cylinder. The magnetos are driven
from each of the two vertical shafts by small bevel
pinions meshing in bevel gears. The carburetor is
mounted between the two cylinder blocks and feeds the
two blocks through aluminum manifolds which are partly
water-jacketed. The engine can be equipped with a
geared hand crank-starting device.

STURTEVANT MODEL 5A 140 HORSE-POWER ENGINE

These motors are of the eight-cylinder "V" type, four-
stroke cycle, water-cooled, having a bore of 4 inches and
a stroke of 5% inches, equivalent to 102 mm. x 140 mm.
The normal operating speed of the crank-shaft is 2,000
E. P. M. The propeller shaft is driven through reducing
gears which can be furnished in different gear ratios.
The standard ratio is 5.3, allowing a propeller speed of
1,200 E. P. M.

The construction of the motor is such as to permit
of the application of a direct drive. The change from the
direct drive to gear drive, or vice versa, can be accom-
plished in approximately one hour.

The cylinders are cast in pairs from an aluminum
alloy and are provided with steel sleeves, carefully fitted
into each cylinder. A perfect contact is secured between
cylinder and sleeve; at the same time a sleeve can be
replaced without injury to the cylinder proper. No dif-
ficulties due to expansion occur on account of the rapid
transmission of heat and the fact that the sleeve is al-
ways at higher temperature than the cylinder. A moulded
copper asbestos gasket is placed between the cylinder
and the head, permitting the cooling water to circulate

Sturtevant Model 5 A Engine 515

freely and at the same time insuring a tight joint. The
cylinder heads are cast in pairs from an aluminum alloy
and contain ample water passages for circulation of
cooling water over the entire head. Trouble due to hot
valves is thereby eliminated, a most important consid-
eration in the operation of an aeroplane motor. The
water jacket of the head corresponds to the water jacket
of the cylinders and large openings in both allow the
unobstructed circulation of the cooling water. The cylin-
der heads and cylinders are both held to the base by six
long bolts. The valves are located in the cylinder heads
and are mechanically operated. The valves and valve
springs are especially accessible and of such size as to
permit high volumetric efficiency. The valves are con-
structed of hardened tungsten steel, the heads and stems
being made from one piece. The valve rocker arms
located on the top of the cylinder are provided with
adjusting screws. A check nut enables the adjusting
screw to be securely locked in position, once the correct
clearance has been determined. The rocker arm bearings
are adequately lubricated by a compression grease cup:
Cam-rollers are interposed between the cams and the
push rods in order to reduce the side thrust on the push
rods.

A system of double springs is employed which greatly
reduces the stress on each spring and insures utmost
reliability. A spring of extremely large diameter returns
the valve; a second spring located at the cylinder base
handles the push rod linkage. These springs, which
operate under low stress, are made from the best of steel
and are given a special double heat treatment. The
pistons are made from a special aluminum alloy; are
deeply ribbed in the head for cooling and strength and
provided with two piston rings. These pistons are ex-
ceedingly light weight in order to minimize vibration and
prevent wear on the bearings. The piston pin is made of
chrome nickel steel, bored hollow and hardened. It is
allowed to turn, both in piston and connecting rod. The

516 Aviation Engines

piston rings are of special design, developed after years
of experimenting in aeronautical engines.

The connecting rods are of "H" section, machined
all over from forgings of a special air-hardening chrome
nickel steel which, after being heat treated has- a tensile
strength of 280,000 pounds per square inch. They are
consequently very strong and yet unusually light, and
being machined all over are of absolutely uniform section,
which gives as nearly perfect balance as can be obtained.
The big ends are lined with white metal and the small
ends are bushed with phosphor bronze. The connecting
rods are all alike and take their bearings side by side on
the crank-pin, the cylinders being offset to permit of
this arrangement. The crank-shaft is machined from
the highest grade chrome nickel steel, heat treated in
order to obtain the best properties of this material.
It is 2% inches in diameter (57 mm.) and bored hollow
throughout, insuring maximum strength with minimum
weight. It is carried in three large, bronze-backed white
metal bearings. A new method of producing these bear-
ings insures a perfect bond between the two metals and
eliminates breakage.

The base is cast from an aluminum alloy. Great
strength and rigidity is combined with light weight. The
sides extend considerably below the center line of the
crank-shaft, providing an extremely deep section. At
all highly stressed points, deep ribs are provided to dis-
tribute the load evenly and eliminate bending. The lower
half of the base is of cast aluminum alloy of extreme
lightness. This collects the lubricating oil and acts as
a small reservoir for same. An oil-filtering screen of
large area covers the entire surface of the sump. The
propeller shaft is carried on two large annular ball bear-
ings driven from the crank- shaft by hardened chrome
nickel steel spur gears. These gears are contained within
an oil-tight casing integral with the base on the oppo-
site end from the timing gears. A ball -thrust bearing
is provided on the propeller shaft to take the thrust of

Sturtevant Model 5 A Engine 517

a propeller or tractor, as the case may be. In case of the
direct drive a stub shaft is fastened direct to the crank-
shaft and is fitted with a double thrust bearing.

The cam-shaft is contained within the upper half of
the base between the two groups of cylinders, and is
supported in six bronze bearings. It is bored hollow
throughout and the cams are formed integral with the
shaft and ground to the proper shape and finish. An
important development in the shape of cams has resulted
in a maintained increase of power at high speeds. The
gears operating the cam-shaft, magneto, oil and water
pumps are contained within an oil-tight casing and oper-
ate in a bath of oil.

Lubrication is of the complete forced circulating sys-
tem, the oil being supplied to every bearing under high
pressure by a rotary pump of large capacity. This is
operated by gears from the crank-shaft. The oil passages
from the pump to the main bearings are cast integral
with the base, the hollow crank-shaft forming a passage
through the connecting rod bearings and the hollow cam-
shaft distributing the oil to the cam-shaft bearings. The
entire surface of the lower half of the base is covered
with a fine mesh screen through which the oil passes
before reaching the pump. Approximately one gallon of
oil is contained within the base and this is continually
circulated through an external tank by a secondary pump
operated by an eccentric on the cam-shaft. This also
draws fresh oil from the external tank which can be made
of any desired capacity.

SPECIFICATIONS MODEL 5A TYPE 8

Horse-power rating, 140 at 2,000 E. P. M.

Bore, 4 inches = 102 mm.

Stroke, 5^ inches = 140 mm.

Number of cylinders, 8.

Arrangement of cylinders, "V."

Cooling, water. Circulation by centrifugal pump.

518 Aviation Engines

Cycle, four stroke.

Ignition (double), 2 Bosch or Splitdorf magnetos.

Carburetor, Zenith duplex. Water jacket manifold.

Oiling system, complete forced. Circulating gear pump.

Normal crank-shaft speed, 2,000 E. P. M.

Propeller shaft, % crank-shaft speed at normal, 1,200

E. P. M.

Stated power at 30" barometer, 140 B. H. P.
Stated weight with all accessories but without water,

gasoline or oil, 514 pounds = 234 kilos.
Weight per B. H. P., 3.7 pounds = 1.68 kilos.
Stated weight with all accessories with water, 550 pounds

-250 kilos.
Weight per B. H. P. with water, 3.95 pounds = 1.79

kilos.

THE CURTISS AVIATION MOTORS

The Curtiss OX motor has eight cylinders, 4-inch
bore, 5-inch stroke, delivers 90 horse-power at 1,400 turns,
and the weight turns out at 4.17 pounds per horse-power.
This motor has cast iron cylinders with monel metal
jackets, overhead inclined valves operated by means of
two rocker arms, push-and-pull rods from the central
cam-shaft located in the crank-case. The cam and push
rod design is extremely ingenious and the whole valve
construction turns out very light. This motor is an
evolution from the early Curtiss type motor which was
used by Glenn Curtiss when he won the Gordon Bennett
Cup at Eheims. A slightly larger edition of this type
motor is the OXX 5, as shown at Figs. 231 and 232,
which has cylinders 4^ inches by 5 inches, delivers 100
horse-power at 1,400 turns and has the same fuel and
oil consumption as the OX type motor, namely, .60 pound
of fuel per brake horse-power hour and .03 pound of
lubricating oil per brake horse-power hour.

The Curtiss Company have developed in the last
two years a larger-sized motor now known as the V-2,
which was originally rated at 160 horse-power and which

Curtis s Aviation Motors

519

has since been refined and improved so that the motor
gives 220 horse-power at 1,400 turns, with a fuel con-
sumption of 5 %oo of a pound per brake horse-power hour
and an oil consumption of .02 of a pound per brake
horse-power hour. This larger motor has a weight of 3.45
pounds per horse-power and is now said to be giving

ive Action

Water-""
Jacketed *
Intake Pipe ^

Oil Gauge

arburetor

Fig. 231. The Curtiss OXX5 Aviation Engine is an Eight-Cylinder Type
Largely Used on Training Machines.

very satisfactory service. The V-2 motor has drawn
steel cylinders, with a bore of 5 inches and a stroke of
7 inches, with a steel water jacket top and a monel metal
cylindrical jacket, both of which are brazed on to the
cylinder barrel itself. Both these motors use side by
side connecting rods and fully forced lubrication. The
cam-shafts act as a gallery from which the oil is dis-
tributed to the cam-shaft bearings, the main crank- shaft

520

Aviation Engines

bearings, and the gearing. Here again we find extremely
short rods, which, as before mentioned, enables the height
and the consequent weight of construction to be very
much reduced. For ordinary flying at altitudes of 5,000

Propeller
Hub

Viewed "From
Top

Removable Sump Screen

Carburetor

Viewed "from
Bottom *

Water ft pe

Fig. 232. Top and Bottom Views of the Curtiss OXX5 100 Horse-Power

Aviation Engine.

to 6,000 feet, the motors are sent out with an aluminum
liner, bolted between the cylinder and the crank-case in
order to give a compression ratio which does not result
in pre-ignition at a low altitude. For high flying, how-
ever, these aluminum liners are taken out and, the com-

Thomas Morse Engine 521

pression volume is decreased to about 18.6 per cent, of
the total volume.

The Curtiss Aeroplane Company announces that it has
recently built, and is offering, a twelve-cylinder 5" x 7"
motor, which was designed for aeronautical uses primar-
ily. This engine is rated at 250 horse-power, but it is
claimed to develop 300 at 1,400 E. P. M. Weights Motor,
1,125 pounds; radiator, 120 pounds; cooling water, 100
pounds; propeller, 95 pounds.

Gasoline Consumption per Horse-power Hour, %o
pounds.

Oil Consumption per Hour at Maximum Speed 2
pints.

Installation Dimensions Overall length, 84% inches;
overall width, 34% inches; overall depth, 40 inches;
width at bed, 30% inches; height from bed, 21% inches;
depth from bed, 18% inches.

THOMAS-MORSE MODEL 88 ENGINE

The Thomas-Morse Aircraft Corporation of Ithaca,
N. Y., has produced a new engine, Model 88, bearing a
close resemblance to the earlier model. The main features
of that model have been retained; in fact, many parts
are interchangeable in the two engines. Supported by
the great development in the wide use of aluminum, the
Thomas engineers have adopted this material for cylinder
construction, which adoption forms the main departure
from previous accepted design.

The marked tendency to-day toward a higher speed
of rotation has been conclusively justified, in the opinion
of the Thomas engineers, by the continued reliable per-
formance of engines with crank-shafts operating at speeds
near 2,000 revolutions per minute, driving the propeller
through suitable gearing at the most efficient speed.
High speed demands that the closest attention be paid
to the design of reciprocating and rotating parts and
their adjacent units. Steel of the highest obtainable

522 Aviation Engines

tensile strength must be used for connecting rods and
piston pins, that they may be light and yet retain a
sufficient factor of safety. Piston design is likewise
subjected to the same strict scrutiny. At the present
day, aluminum alloy pistons operate so satisfactorily
that they may be said to have come to stay.

The statement often made in the past, that the gear-
ing down of an engine costs more in the weight of re-
duction gears and propeller shaft than is warranted by
the increase in horse-power, is seldom heard to-day.

The mean effective pressure remaining the same, the
brake horse-power of any engine increases as the speed.
That is, an engine delivering 100 brake horse-power at
1,500 revolutions per minute will show 133 brake horse-
power at 2,000 revolutions per minute, an increase of 33
brake horse-power. To utilize this increase in horse-
power, a matter of some fifteen pounds must be spent
in gearing and another fifteen perhaps on larger valves,
bearings, etc. Two per cent, may be assumed lost in
the gears. In other words, the increase in horse-power
due to increasing the speed has been attained at the
expense of about one pound per brake horse-power.

The advantages of the eight-cylinder engine over the
six and twelve, briefly stated, are : lower weight per horse-
power, shorter length, simpler and stiffer crank-shaft,
cam-shaft and crank-case, and simpler and more direct
manifold arrangement. As to torque, the eight is supe-
rior to the six, and yet in practice not enough inferior
to the twelve to warrant the addition of four more
cylinders. It must, however, be recognized that the
eight is subject to the action of inherent unbalanced
inertia couples, which set up horizontal vibrations, im-
possible of total elimination. These vibrations are func-
tions of the reciprocating weights, which, as already
mentioned, are cut down to the minimum. Vibrations
due to the elasticity of crank-case, crank-shaft, etc., -can
be and are reduced in the Thomas engine to minor
quantities by ample webbing of the crank-case and judi-

Thomas -Morse Engine 523

cious use of metal elsewhere. All things considered,
there is actually so little difference to be discerned be-
tween the balance of a properly designed eight-cylinder
engine and that of a six or twelve as to make a dis-
cussion of the pros and cons more one of theory than
of practice.

The main criticisms of the L head cylinder engine are
that it is less efficient and heavier. This is granted, as it
relates to cylinders alone. More thorough investigation,
however, based on the main desideratum, weight-power
ratio, leads us to other conclusions, particularly with
reference to high speed engines. The valve gear must
not be forgotten. A cylinder cannot be taken completely
away from its component parts and judged, as to its
weight value, by itself alone. A part away from the whole
becomes an item unimportant in comparison with the
whole. The valve gear of a high speed engine is a too
often overlooked feature. The stamp of approval has
been made by high speed automobile practice upon the
overhead cam-shaft drive, with valves in the cylinder
head operated direct from the cam-shaft or by means of
valve lifters or short rockers.

The overhead cam-shaft mechanism applied to an
eight-cylinder engine calls for two separate cam-shafts
carried above and supported by the cylinders in an oil-
tight housing, and driven by a series of spur gears or
bevels from the crank-shaft. It is patent that this valve
gearing is heavy and complicated in comparison with
the simple moving valve units of the L head engine,
which are operated from one single cam-shaft, housed
rigidly in the crank-case. The inherently lower volu-
metric efficiency of the L head engine is largely overcome
by the use of a properly designed head, large valves and
ample gas passages. Again, the customary use of a dual
ignition system gives to the L head a relatively better
opportunity for the advantageous placing of spark-plugs,
in order that better flame propagation and complete
combustion may be secured.

524

Aviation Engines

The Thomas Model 88 engine is 4%-inch bore and
5%-inch stroke. The cylinders and cylinder heads are
of aluminum, and as steel liners are used in the cylinders

Fig. 233. End View of Thomas-Morse 150 Horse-Power Aluminum Cylinder
Aviation Motor Having Detachable Cylinder Heads.

the pistons are also made of aluminum. This engine is
actually lighter than the earlier model of less power.
It weighs but 525 pounds, with self-starter. The general

Sixteen-V 'alve Duesenberg Engine

525

features of design can be readily ascertained by study
of the illustrations : Fig. 233, which shows an end view ;
Fig. 234, which is a side view, and Fig. 235, which out-

Fig. 234. Side View of Thomas-Morse High Speed 150 Horse-Power
Aviation Motor with Geared Down Propeller Drive.

lines the reduction gear-case and the propeller shaft
supporting bearings.

SIXTEEN-VALVE DUESENBERG ENGINE

This engine is a four-cylinder, 4%"x7", 125 horse-
power at 2,100 E. P. M. of the crank-shaft and 1,210
E. P. M. of the propeller. Motors are sold on above
rating; actual power tests prove this motor capable of
developing 140 horse-power at 2,100 E. P. M. of the
motor. The exact weight with magneto, carburetor, gear
reduction and propeller hub, as illustrated, 509 pounds;
without gear reduction, 436 pounds. This motor has
been produced as a power plant weighing 3.5 pounds per
horse-power, yet nothing has been sacrificed in rigidity
and strength. At its normal speed it develops 1 horse-

526

Aviation Engines

power for every 3.5 cubic inches piston displacement.
Cylinders are semi-steel, with aluminum plates enclosing
water jackets. Pistons specially ribbed and made of
Magnalite aluminum compound. Piston rings are special
Duesenberg design, being three-piece rings. Valves are

Fig. 235. The Reduction Gear-Case of Thomas-Morse 150 Horse-Power
Aviation Motor, Showing Ball Bearing and Propeller Drive Shaft Gear.

tungsten steel, 1 1 % 6 " inlets and 2" exhausts, two of each
to each cylinder. Arranged horizontally in the head,
allowing very thorough water- jacketing. Inlet valves in
cages. Exhaust valves, seating directly in the cylinder
head, are removable through the inlet valve holes. Valve
stems lubricated by splash in the valve action covers.
Valve rocker arms forged with cap screw and nut at

Siocteen-V alve Dues enb erg Engine 527

upper end to adjust clearance. Entirely enclosed by
aluminum housing, as is entire valve mechanism. Con-
necting rods are tubular, chrome nickel steel, light and
strong. Crank-shaft is one-piece forging, hollow bored,
2i/2-inch diameter at main bearings. Connecting rod
bearings, 214-inch diameter, 3 inches long. Front main
bearing, 3% inches long; intermediate main bearing,
31/2 inches long ; rear main bearing, 4 inches long. Crank-
case of aluminum, barrel type, oil pan on bottom remov-
able. Hand hole plates on both sides. Strongly webbed.
The oiling system of this sixteen-valve Duesenberg
motor is one of its vital features. An oil pump located
in the base and submerged in oil forces oil through cored
passages to the three main bearings, then through tubes
under each connecting rod into which the rod dips. The
oil is thrown off from these and lubricates every part of
the motor. This constitutes the main oiling system; it is
supplemented by a splash system, there being a trough
under each connecting rod into which the rod slips. The
oil is returned to the main supply sump by gravity,
where it is strained and re-used. Either system is in
itself sufficient to operate the motor. A pressure gauge
is mounted for observation on a convenient part of the
system. A pressure of approximately 25 pounds is
maintained by the pressure system, which insures effi-
cient lubrication at all speeds of the motor. The troughs
under the connecting rods are so constructed that no
matter what the angle of flight may be, oil is retained
in each individual trough so that each connecting rod
can dip up its supply of oil at each revolution.

AEROMARINE SIX-CYLINDER VERTICAL MOTOR

These motors are four-stroke cycle, six-cylinder ver-
tical type, with cylinder 4>i // bore by 5%" stroke. The
general appearance of this motor is shown in illustra-
tion at Fig. 236. This engine is rated at 85-90 horse-
power. All reciprocating and revolving parts of this

-528 Aviation Engines

motor are made of the highest grades of steel obtainable
as are the studs, nuts and bolts. The upper and lower
parts of crank-case are made of composition aluminum
casting. Lower crank-case is made of high grade alu-
minum composition casting and is bolted directly to the
upper half. The oil reservoir in this lower half casting
provides sufficient oil capacity for five hours' continuous
running at full power. Increased capacity can be pro-

e-Water Pm'e

^tfuraijyfLiJB&HiBiyftLi

Magneto

Water /
Pum.p

O'rt Pump

Fig. 236. The Six-Cylinder Aeromarine Engine.

vided if needed to meet greater endurance requirements.
Oil is forced under pressure to all bearings by means of
high-pressured duplex-geared pumps. One side of this
pump delivers oil under pressure to all the bearings,
while the other side draws the oil from the splash case
and delivers it to the main sump. The oil reservoir is
entirely separate from the crank-case chamber. Under
no circumstances will oil flood the cylinder, and the oiling
system is not affected in any way by any angle of flight
or position of motor. An oil pressure gauge is placed
on instrument board of machine, which gives at all times

Aeromarine Aviation Engine 529

the pressure in oil system, and a sight glass at lower
half of case indicates the amount of oil contained. The
oil pump is external on magneto end of motor, and is
very accessible. An external oil strainer is provided,
which is removable in a few minutes' time without the
loss of any oil. All oil from reservoir to the motor passes
through this strainer. Pressure gauge feed is also at-
tached and can be piped to any part of machine desired.

The cylinders are made of high-grade castings and
are machined and ground accurately to size. Cylinders
are bolted to crank-case with chrome nickel steel studs
and nuts which securely lock cylinder to upper half of
crank-case. The main retaining cylinder studs go
through crank-case and support crank-shaft bearings so
that crank-shaft and cylinders are tied together as one
unit. Water jackets are of copper, %e" thick, electrically
deposited. This makes a non-corrosive metal. Cooling
is furnished by a centrifugal pump, which delivers 25
gallons per minute 1,400 E. P. M. Pistons are made
cast iron, accurately machined and ground to exact di-
mensions, which are carefully balanced. Piston rings are
semi- steel rings of Aeromarine special design.

Connecting rods are of chrome nickel steel, H-section.
Crank-shaft is made of chrome nickel steel, machined all
over, and cut from solid billet, and is accurately bal-
anced through the medium of balance weights being
forged integral with crank. It is drilled for lightness and
plugged for force feed lubrication. There are seven
main bearings to crank-shaft. All bearings are of high-
grade babbitt, die cast, and are interchangeable and easily
replaced. The main bearings of the crank-shaft are
provided with a single groove to take oil under pressure
from pressure tube which is cast integral with case.
Connecting rod bearings are of the same type. The
gudgeon pin is hardened, ground and secured in con-
necting rod, and is allowed to work in piston. Cam-shaft
is of steel, with cams forged integral, drilled for light-
ness and forced-feed lubrication, and is case-hardened.

530

Aviation Engines

Fig. 237. The Wisconsin Aviation Engine, at Top, as Viewed from
Carburetor Side. Below, the Exhaust Side.

Wisconsin Aviation Engine

531

The bearings of cam-shaft are of bronze. Magneto, two
high-tension Bosch D. U. 6. The intake manifold for
carburetors are aluminum castings and are so designed
that each carburetor feeds three cylinders, thereby insur-
ing easy flow of vapor at all speeds. Weight, 420 pounds.

WISCONSIN AVIATION ENGINES

The new six-cylinder Wisconsin aviation engines, one
of which is shown at Fig. 237, are of the vertical type,

Fig. 238. Dimensioned End Elevation of Wisconsin Six Motor.

with cylinders in pairs and valves in the head. Dimen-
sioned drawings of the six-cylinder vertical type are
given at Figs. 238 and 239. The cylinders are made of
aluminum alloy castings, are bored and machined and
then fitted with hardened steel sleeves about %e inch in
thickness. After these sleeves have been shrunk into
the cylinders, they are finished by grinding in place.
Gray iron valve seats are cast into the cylinders. The
valve seats and cylinders, as well as the valve ports, are

532

Aviation Engines

entirely surrounded by water jackets. The valves set
in the heads at an angle of 25 from the vertical, are
made of tungsten steel and are provided with double
springs, the outer or main spring and the inner or aux-
iliary spring, which is used as a precautionary measure
to prevent a valve falling into the cylinder in remote
case of a main spring breaking. The cam-shaft is made
of one solid forging, case-hardened. It is carried in an

Fig. 239. Dimensioned Side Elevation of Wisconsin Six Motor.

aluminum housing bolted to the top of the cylinders.
This housing is split horizontally, the upper half carrying
the chrome vanadium steel rocker levers. The lower half
has an oil return trough cast integral, into which the
excess oil overflows and then drains back to the crank-
case. Small inspection plates are fitted over the cams
and inner ends of the cam rocker levers. The cam-shaft
runs in bronze bearings and the drive is through ver-
tical shaft and bevel gears. '
The crank-case is made of aluminum, the upper half

Wisconsin Aviation Engine 533

carrying the bearings for the crank-shaft. The lower
half carries the oil sump in which all of the oil except
that circulating through the system at the time is carried.
The crank- shaft is made of chrome vanadium steel of
an elastic limit of 115,000 pounds. The crank-pins and
ends of the shaft are drilled for lightness and the cheeks
are also drilled for oil circulation. The crank-shaft runs
in bronze-backed, Fahrig metal-lined bearings, four in
number. A double thrust bearing is also provided, so
that the motor may be used either in a tractor or pusher
type of machine. Outside of the thrust bearing an annu-
lar ball bearing is used to take the radial load of the
propeller. The propeller is mounted on a taper. At the
opposite end of the shaft a bevel gear is fitted which
drives the cam-shaft, through a vertical shaft, and also
drives the water and oil pumps and magnetos. All gears
are made of chrome vanadium steel, heat-treated.

The connecting rods are tubular and machined from
chrome vanadium steel forgings. Oil tubes are fitted to
the rods which carry the oil up to the wrist-pins and
pistons. The rods complete with bushings weigh 5%
pounds each. The pistons are made of aluminum alloy
and are very light and strong, weighing only 2 pounds
2 ounces each. Two leak-proof rings are fitted to each
piston. The wrist-pins are hollow, of hardened steel,
and are free to turn either in the piston or the rod. A
bronze bushing is fitted in the upper end of the rod, but
no bushing is fitted in the pistons, the hardened steel
wrist-pins making an excellent bearing in the aluminum
alloy.

The water circulation is by centrifugal pump, which
is mounted at the lower end of the vertical shaft. The
water is pumped through brass pipes to the lower end
of the cylinder water jackets and leaves the upper end
of the jackets just above the exhaust valves. The lubri-
cating system is one of the main features of the engines,
being designed to w r ork with the motor at any angle.
The oil is carried in the sump, from where it is taken

534

Aviation Engines

by the oil circulating pump through a strainer and forced
through a header, extending the full length of the crank-
case, and distributed to the main bearings. From the
main bearings it is forced through the hollow crank-
shaft to the connecting rod big ends and then through

800

ZOO 400 600 800 1000 IZOO 1400 1600 1800 ZOOO ZZOO Z400
Revolutions per Minu+e

Fig. 240. Power, Torque and Efficiency Curves of Wisconsin Aviation

Motor.

Wisconsin Aviation Engine

535

tubes on the rods to wrist-pins and pistons. Another
lead takes oil from the main header to the cam-shaft
bearings. The oil forced out of the ends of the cam-
shaft bearings fills pockets under the cams and in the
cam rocker levers. The excess flows back through pipes
and through the train of gears to the crank-case. A
strainer is fitted at each end of the crank-case, through
which the oil is drawn by separate pumps and returned
to the sump. Either one of these pumps is large enough

Exhaust Closes
Inlet Opens

Firing Order I - 4-2- 6- 3- S

Fig. 241. Timing Diagram, Wisconsin Aviation Engine.

to take care of all of the return oil, so that the operation
is perfect whether the motor is inclined up or down. No
splash is used in the crank-case, the system being a
full force feed. An oil level indicator is provided, show-
ing the amount of oil in the sump at all times. The oil
pressure in these motors is carried at ten pounds, a
relief valve being fitted to hold the pressure constant.

Ignition is by two Bosch magnetos, each on a separate
set of plugs fired simultaneously on opposite sides of the
cylinders. Should one magneto fail, the other would still
run the engine at only a slight loss in power. The Zenith
double carburetor is used, three cylinders being supplied
by each carburetor. This insures a higher volumetric
efficiency, which means more power, as there is no over-

536 Aviation Engines

lapping of inlet valves whatever by this arrangement.
All parts of these motors are very accessible. The water
and oil pumps, carburetors, magnetos, oil strainer or
other parts can be removed without disturbing other
parts. The lower crank-case can be removed for in-
spection or adjustment of bearings, as the crank-shaft and
bearing caps are carried by the upper half. The motor
supporting lugs are also part of the upper crank-case.

The six-cylinder motor, without carburetors or mag-
netos, weighs 547 pounds. With carburetor and mag-
netos, the weight is 600 pounds. The weight of cooling
water in the motor is 38 pounds. The sump will carry
4 gallons of oil, or about 28 pounds. A radiator can be
furnished suitable for the motor, weighing 50 pounds.
This radiator will hold 3 gallons of water or about 25
pounds. The motor will drive a two-blade, 8 feet diame-
ter by 6.25 feet pitch Paragon propeller 1400 revolutions
per minute, developing 148 horse-power. The weight of
this propeller is 42 pounds. This makes a total weight
of motor, complete with propeller, radiator filled with
water, but without lubricating oil, 755 pounds, or about
5.1 pounds per horse-power for complete power plant.
The fuel consumption is .5 pound per horse-power per
hour. The lubricating oil consumption is .0175 pound
per horse-power per hour, or a total of 2.6 pounds per
hour at 1400 revolutions per minute. This would make
the weight of fuel and oil, per hour's run at full power
at 1400 revolutions per minute, 76.6 pounds.

PKINCIPAL DIMENSIONS

Following are the principal dimensions of the six-
cylinder motor:

Bore 5 inches.

Stroke 6% inches.

Crank-shaft diameter throughout 2 inches.

Length of crank-pin and main bearings 3% inches.

Diameter of valves 3 inches (2% inches clear).

Wisconsin Aviation Engine 537

Lift of valves y% inch.

Volume of compression space 22 per cent, of total.

Diameter of wrist-pins l%e inches.

Firing order 1-4-2-6-3-5.

The horse-power developed at 1200 revolutions per
minute is 130, at 1300 revolutions per minute 140, at
1400 revolutions per minute 148. 1400 is the maximum
speed at which it is recommended to run these motors.

TWELVE-CYLINDER ENGINE

A twelve-cylinder V-type engine illustrated, is also
being built by this company, similar in dimensions of
cylinders to the six. The principal differences being in
the drive to cam-shaft, which is through spur gears in-
stead of bevel. A hinged type of connecting rod is used
which does not increase the length of the motor and, at
the same time, this construction provides 'for ample bear-
ings. A double centrifugal water pump is provided for
this motor, so as to distribute the water uniformly to
both sets of cylinders. Four magnetos are used, two for
each set of six cylinders. The magnetos are very acces-
sibly located on a bracket on the spur gear cover. The
carburetors are located on the outside of the motors,
where they are very accessible, while the exhaust is in the
center of the valley. The crank-shaft on the twelve is
2y 2 inches in diameter and the shaft is bored to reduce
weight. Dimensioned drawings of the twelve-cylinder
engine are given at Figs. 242 and 243 and should prove
useful for purposes of comparison with other motors.

HALL-SCOTT AVIATION ENGINES

The following specifications of the Hall-Scott "Big
Four" engines apply just as well to the six-cylinder
vertical types which are practically the same in construc-
tion except for the structural changes necessary to ac-
commodate the two extra cylinders. Cylinders are cast

538

Aviation Engines

separately from a special mixture of semi-steel, having
cylinder head with valve seats integral. Special attention
has been given to the design of the water jacket around
the valves and head, there being two inches of water

Tig. 242. Dimensioned End View of Wisconsin Twelve-Cylinder Airplane

Motor.

space above same. The cylinder is annealed, rough
machined, then the inner cylinder wall and valve seats
ground to mirror finish. This adds to the durability of
the cylinder, and diminishes a great deal of the excess
friction.

Hall- Scott Engines

539

Great care is taken in the casting and machining of
these cylinders, to have the bore and walls concentric
with each other. .Small ribs are cast between outer and
inner walls to assist cooling as well as to transfer stresses
direct from the explosion to hold-down bolts which run
from steel main bearing caps to top of cylinders. The
cylinders are machined upon the sides so that when
assembled on the crank-case with grooved hold-down

Fig. 243. Dimensioned Side Elevation of Wisconsin Twelve-Cylinder Air-
plane Motor.

wafers tightened, they form a solid block, greatly assist-
ing the rigidity of crank-case.

The connecting rods are very light, being of the I
beam type, milled from a solid Chrome nickel die forging.
The caps are held on by two %"-20 thread Chrome nickel
through bolts. ' The rods are first roughed out, then an-
nealed. Holes are drilled, after which the rods are hard-
ened and holes ground parallel with each other. The
piston end is fitted with a gun metal bushing, while the
crank-pin end carries two bronze serrated shells, which
are tinned and babbitted hot, being broached to harden
the babbitt. Between the cap and rod proper are placed

540 Aviation Engines

laminated shims for adjustment. Crank-cases are cast of
the best aluminum alloy, hand scraped and sand blasted
inside and out. The lower oil case can be removed with-
out breaking any connections, so that the connecting rods
and other working parts can readily be inspected. An
extremely large strainer and dirt trap is located in the
center and lowest point of the case, which is easily re-
moved from the outside without disturbing the oil pump
or any working parts. A Zenith carburetor is provided.
Automatic valves and springs are absent, making the
adjustment simple and efficient. This carburetor is not
affected by altitude to any appreciable extent. A Hall-
Scott device, covered by U. S. Patent No. 1,078,919, allows
the oil to be taken direct from the crank-case and run
around the carburetor manifold, which assists carburetion
as well as reduces crank-case heat. Two waterproof four-
cylinder Splitdorf " Dixie " magnetos are provided. Both
magneto interrupters are connected to a rock shaft in-
tegral with the motor, making outside connections unneces-
sary. It is worthy of note that with this independent
double magneto system, one complete magneto can become
inoperative, and still the motor will run and continue to
give good power.

The pistons as provided in the A-7 engines are cast
from a mixture of steel and gray iron. These are ex-
tremely light, yet provided with six deep ribs under the
arch head, greatly aiding the cooling of the piston as well
as strengthening it. The piston pin bosses are located
very low in order to keep the heat from the piston head
away from the upper end of the connecting rod, as well
as to arrange them at the point where the piston fits the
cylinder best. Three ^4" rings are carried. The pistons
as provided in the A-7a engines are cast from aluminum
alloy. Four 14" rings are carried. In both piston types
a large diameter, heat treated, Chrome nickel steel wrist-
pin is provided, assembled in such a way as to assist the
circular rib between the wrist-pin bosses to keep the
piston from being distorted from the explosions.

Hall-Scott Engines 541

The oiling system is known as the high pressure type,
oil being forced to the under side of the main bearings
with from 5 to 30 points pressure. This system is not
affected by extreme angles obtained in flying, or whether
the motor is used for push or pull machines. A large
gear pump is located in the lowest point of the oil sump,
and being submerged at all times with oil, does away
with troublesome stuffing boxes and check valves. The
oil is first drawn from the strainer in oil sump to the long
jacket around the intake manifold, then forced to the
main distributor pipe in crank-case, which leads to all
main bearings. A bi-pass, located at one end of the
distributor pipe, can be regulated to provide any pres-
sure required, the surplus oil being returned to the case.
A special feature of this system is the dirt, water and
sediment trap, located at the bottom of the oil sump.
This can be removed without disturbing or dismantling
the oil pump or any oil pipes. A small oil pressure gauge
is provided, which can 'be run to the aviator's instrument
board. This registers the oil pressure, and also deter-
mines its circulation.

The cooling of this motor is accomplished by the oil
as well as the water, this being covered by patent No.
1,078,919. This is accomplished by circulating the oil
around a long intake manifold jacket; the carburetion
of gasoline cools this regardless of weather conditions.
Crank-case heat is therefore kept at a minimum. The
uniform temperature of the cylinders is maintained by/
the use of ingenious internal outlet pipes, running through
the head of each of the six-cylinders, rubber hose con-
nections being used so that any one of the cylinders may
be removed without disturbing the others. Slots are cut
in these pipes so that cooler water is drawn directly
around the exhaust valves. Extra large water jackets
are provided upon the cylinders, two inches of water
space is left above the valves and cylinder head. The
water is circulated by a large centrifugal pump insuring
ample circulation at all speeds.

542 Aviation Engines

The crank-shaft is of the five bearing type, being
machined from a special heat treated drop forging of the
highest grade nickel steel. The forging is first drilled,
then roughed out. After this the shaft is straightened,
turned down to a grinding size, then ground accurately
to size. The bearing surfaces are of extremely large
size, over-size, considering general practice in the build-
ing of high speed engines of similar bore and stroke.
The crank-shaft bearings are 2" in diameter by l 15 Ae //
long, excepting the rear main bearing, which is 4%"
long, and front main bearing, which is 2% 6 " long. Steel
oil scuppers are pinned and sweated onto the webs of
the shaft, which allows of properly oiling the connecting
rod bearings. Two thrust bearings are installed on the
propeller end of the shaft, one for pull and the other for
push. The propeller is driven by the crank-shaft flange,
which is securely held in place upon the shaft by six
keys. These drive an outside propeller flange, the pro-
peller being clamped between them by six through bolts.
The flange is fitted to a long taper on crank-shaft. This
enables the propeller to be removed without disturbing
the bolts. Timing gears and starting ratchets are bolted
to a flange turned integral with shaft.

The cam-shaft is of the one piece type, air pump
eccentric, and gear flange being integral. It is made
from a low carbon specially heat treated nickel forging,
is first roughed out and drilled entire length ; the cams
are then formed, after which it is case hardened and
ground to size. The cam-shaft bearings are extra long,
made from Parson 's White Brass. A small clutch is
milled in gear end of shaft to drive revolution indicator.
The cam-shaft is enclosed in an aluminum housing bolted
directly on top of all six cylinders, being driven by a
vertical shaft in connection with bevel gears. This shaft,
in conjunction with rocker arms, rollers and other work-
ing parts, are oiled by forcing the oil into end of shaft,
using same as a distributor, allowing the surplus supply
to flow back into the crank-case through hollow vertical

Hall-Scott Engine Details 543

tube. This supply oils the magneto and pump gears.
Extremely large Tungsten valves, being one-half the cylin-
der diameter, are seated in the cylinder heads. Large
diameter oil tempered springs held in tool steel cups,
locked with a key, are provided. The ports are very
large and short, being designed to .allow the gases to en-
ter and exhaust with the least possible resistance. These
valves are operated by overhead one piece cam-shaft in
connection with short Chrome nickel rocker arms. These
arms have hardened tool steel rollers on cam end with
hardened tool steel adjusting screws opposite. This conr
struction allows accurate valve timing at all speeds with
least possible weight.

CENSORED

GERMAN AIRPLANE MOTORS

In a paper on "Aviation Motors," presented by E. H.
Sherbondy before the Cleveland section of the S. A. E.
in June, 1917, the Mercedes and Benz airplane motor is
discussed in some detail and portions of the description
follow.

MERCEDES MOTOR

The 150 horse-power six-cylinder Mercedes motor is
140 millimeters bore and 160 millimeters stroke. The
Mercedes company started with smaller-sized cylinders,
namely 100 millimeters bore and 140 millimeters stroke,
six-cylinders. The principal features of the design are
forged steel cylinders with forged steel elbows for gas
passages, pressed steel water jackets, which' when welded

544 Aviation Engines

CENSORED

Argus Engine Construction

545

546

Aviation Engines

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American Aviation Engine

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547

548 Aviation Engines

together forms the cylinder assembly, the use of inclined
overhead valves operated by means of an overhead cam-
shaft through rocker arms which multiply with the mo-
tion of the cam. By the use of steel cylinders, not only
is the weight greatly reduced, but certain freedom from
distortion through unequal sections, leaks and cracks are
entirely avoided. The construction is necessarily very
expensive. It is certainly a sound job. In the details
of this construction there are a number of important
things, such as finished gas passages, water-cooled valve
guides and a very small mass of metal, which is water-
cooled, surrounding the spark-plug. Of course, it is nec-
essary to use very high compression in aviation motors
in order to secure high power and economy and owing to
the fact that aviation motors are worked at nearly their
maximum, the heat flow through the cylinder, piston, and
valves is many times higher than that encountered in
automobile motors. It has been found necessary to de-
velop -special types of pistons to carry the heat from the
center of the head in order to prevent pre-ignition. In
the Mercedes motor the pistons have a drop forged steel
head which includes the piston boss and this head is
screwed into a cast iron skirt which has been machined
inside to secure uniform wall thickness.

The carburetor used on this 150 horse-power Mer-
cedes motor is precisely of the same type used on the
Twin Six motor. It has two venturi throats, in the center
of which is placed the gasoline spray nozzle of conven-
tional type, fixed size orifices, immediately above which
are placed two panel type throttles with side outlets.
An idling or primary nozzle is arranged to discharge
above the top of the venturi throat. The carburetor
body is of cast aluminum and is water jacketed. It is
bolted directly to air passage passing through the top
and bottom half of the crank-case which passes down
through the oil reservoir. The air before reaching the
carburetor proper to some extent has cooled the oil in
the crank chamber and has itself been heated to assist

Mercedes Engine Details

549

in the vaporization. The inlet pipes themselves are cop-
per. All the passages between the venturi throat and
the inlet valve have been carefully finished and polished.
The only abnormal thing in the design of this motor is
the short connecting rod which is considerably less than
twice the stroke and would be considered very bad practice
in motor car engines. A short connecting rod, however,

Fig. 245. Part Sectional View of 90 Horse-Power Mercedes Engine*
Which is Typical of the Design of Larger Sizes.

possesses two very real virtues in that it cuts down height
of the motor and the piston passes over the bottom dead
center much more slowly than with a long rod.

Other features of the design are a very stiff crank-
case, both halves of which are bolted together by means
of long through bolts, the crank- shaft main bearings are
seated in the lower half of the case instead of in the
usual caps and no provision is made for taking up the
main bearings. The Mercedes company uses a plunger

550 Aviation Engines

type of pump having mechanically operated piston valves
and it is driven by means of worm gearing.

The overhead cam-shaft construction is extremely
light. The cam-shaft is mounted in a nearly cylindrical
cast bronze case and is driven by means of bevel gears
from the crank-shaft. The vertical bevel gear shaft
through which the drive is taken from the crank- shaft to
the cam-shaft operates at one and one-half times the
crank-shaft speeds and the reduction to the half-time
cam-shaft is secured through a pair of bevels. On this
vertical shaft there is mounted the water pump and a
bevel gear for driving two magnetos. The water pump
mounted on this shaft tends to steady the drive and avoid
vibration in the gearing.

The cylinder sizes of six-cylinder aviation motors
which have been built by Mercedes are

Bore Stroke Horse-power

105 mm. 140 mm. 100

120 mm. 140 mm. 135

140 mm. 150 mm. 150

140 mm. 160 mm. 160

The largest of these motors has recently had its horse-
power increased to 176 at 1450 K. P. M. This general
design of motor has been the foundation for a great many
other aviation motor designs, some of which have proved
very successful but none of which is equal to the origi-
nal. Among the motors which follow more or less closely
the scheme of design and arrangement are the Hall-Scott,
the "Wisconsin motor, the Eenault water-cooled, the Pack-
ard, the Christofferson and the Eolls-Koyce. Each of
these motors show considerable variation in detail. The
Kolls-Eoyce and Eenault are the only ones who have used
the steel cylinder with the steel jacket. The Wisconsin
motor uses an aluminum cylinder with a hardened steel
liner and cast-iron valve seats. The Christofferson has
somewhat similar design to the Wisconsin with the ex-
ception that the valve seats are threaded into the alumi-

The Benz Motor 551

num. jacket and the cylinder head has a blank end which
is secured to the aluminum casting by means of the valve
seat pieces. The Eolls-Koyce motors show small differ-
ences in details of design in cylinder head and cam-shaft
housing from the Mercedes on which it has taken out
patents, not only abroad but in this country.

THE BE^Z MOTOR

In the Kaiser prize contest for aviation motors a four-
cylinder Benz motor of 130 by 180 mm. won first prize,
developing 103 B. H. P. at 1290 R. P. M. The fuel con-
sumption was 210 grams per horse-power hour. Total
weight of the motor was 153 kilograms. The oil con-
sumption was .02 of a kilogram per horse-power hour.
This motor was afterward expanded into a six-cylinder
design and three different sizes were built.

The accompanying table gives some of the details of
weight, horse-power, etc.

Motor type B FD FF

Rated horse-power 85 100 150

Horse-power at 1250 r.p.m 88 108 150

Horse-power at 1350 r.p.m 95 115 160

Bore in millimeters 106 116 130

Stroke in millimeters 150 160 180

Offset of the cylinders in millimeters 18 20 20

Rate of gasoline consumption in grams 240 230 225

Oil consumption in grams per b.h.p. hour 10 10 10

Oil capacity in kilo'grams 36 4 4%

Water capacity in litres 5 % 7 % 9 y 2

The weight with water and oil but with two

magnetos, fuel feeder and air pump in

kilograms 170 200 245

The weight of motors, including the water

pump, two magnetos, double ignition, etc. . 160 190 230
The weight of the exhaust pipe, complete in

kilograms 4 4.8 5 %

The weight of the propeller hub in kilograms . 3^4 4

The Benz cylinder is a simple, straightforward design
and a very reliable construction and not particularly diffi-
cult to manufacture. The cylinder is cast of iron without

552 Aviation Engines

a water jacket but including 45 degrees angle elbows to
the valve ports. The cylinders are machined wherever
possible and at other points have been hand filed and
scraped, after which a jacket, which is pressed in two
halves, is gas welded by means of short pipes welded on
to the jacket. The bottom and the top of the cylinders
become water galleries, and by this means separate water
pipes with their attendant weight and complication are
eliminated. Eubber rings held in aluminum clamps serve
to connect the cylinders together. The whole construc-
tion turns out very neat and light. The cylinder walls
are 4 mm. or %_$" thick and the combustion chamber is of
cylindrical pancake form and is 140 mm. or 5.60 inch in
diameter. The valve seats are 68 mm. in diameter and
the valve port is 62 mm. in diameter.

The passage joining the port is 57 mm. in diameter.
In order to insert the valves into the cylinder the valve
stem is made with two diameters and the valve has to
be cocked to insert it in the guide, which has a bronze
bushing at its upper end to compensate for the smaller
valve stem diameter. The valve stem is 14 mm. or %G"
in diameter and is reduced at its upper portion to 9y 2 mm.
The valves are operated through a push rod and rocker
arm construction, which is % 6 " and exceedingly light.
Kocker arm supports are steel studs with enlarged heads
to take a double row ball bearing. A roller is mounted
at one end of the rocker arm to impinge on the end of
the valve stem, and the rocker arm has an adjustable
globe stud at the other end. The push rods are light steel
tubes with a wall thickness of 0.75 mm. and have a hard-
ened steel cup at their upper end to engage the rocker
arm globe stud and a hardened steel globe at their lower
end to socket in the roller plunger.

The Benz cam-shaft has a' diameter of 26 mm. and is
bored straight through 18 mm. and there is a spiral gear
made integrally with the shaft in about the center of its
length for driving the oil pump gear. ' The cam faces are
10 mm. wide. There is also, in addition to the intake

The Benz Motor 553

and exhaust cams, a set of half compression cams. The
shaft is moved longitudinally in its bearings by means of
an eccentric to put these cams into action. At the fore
end of the shaft is a driving gear flange which is very
small in diameter and very thin. The flange is 68 mm.
in diameter and 4 mm. thick and is tapped to take 6 mm.
bolts. The total length of cam-shaft is 1038 mm., and it
becomes a regular gun boring job to drill a hole of this
length.

The cam-shaft gear is 140 mm. or 5% inches outside
diameter. It has fifty-four teeth and the gear face is 15
mm. or 1 %2 / '. The flange and web have an average thick-
ness of 4 mm. or %2 r/ ancj, the web is drilled full of holes
interposed between the spur gear mounted on the cam-
shaft and the cam-shaft gear. There is a gear which
serves to drive the magnetos and tachometer, also the
air pump. The shaft is made integrally with this gear
and has an eccentric portion against which the air pump
roll plunger impinges.

The seven-bearing crank-shaft is finished all over in
a beautiful manner, and the shaft out of the particular
motor we have shows no signs of wear whatever. The
crank-pins are 55 mm. in diameter and 69 mm. long.
Through both the crank-pin and main bearings there is
drilled a 28 mm. hole, and the crank cheeks are plugged
with solder. The crank cheeks are also built to convey
the lubricant to the crank-pins. At the fore end of the
crank cheek there is pressed on a spur driving gear.
There is screwed on to the front end of the shaft a piece
which forms a bevel water pump driving gear and the
starting dog. At the rear end of the shaft very close to
the propeller hub mounting there is a double thrust bear-
ing to take the propeller thrust.

Long, shouldered studs are screwed into the top half
of the crank-case portion of the case and pass clean
x through the bottom half of the case. The case is very
stiff and well ribbed. The three center bearing dia-
phragms have double walls. The center one serves as a

554 Aviation Engines

duct through which water pipe passes, and those on either
side of the center form the carburetor intake air passages
and are enlarged in section at one side to take the car-
buretor barrel throttle.

The pistons are of cast iron and carry three concentric
rings 1/4 inch wide on their upper end, which are pinned
at the joint. The top of the piston forms the frustum
of the cone and the pistons are 110 mm. in length. The
lower portion of the skirt is machined inside and has a
wall thickness of 1 mm. Kiveted to the piston head is
a conical diaphragm which contacts with the piston pin
when in place and serves to carry the heat off the center
of the piston.

The oil pump assembly comprises a pair of plunger
pumps which draw oil from a separate outside pump, and
constructed integrally with it is a gear pump which de-
livers the oil under about 60 pound pressure through a
set of copper pipes in the base to the main bearings. The
plunger oil pump shows great refinement of detail. A
worm wheel and two eccentrics are machined up out of
one piece and serve to operate the plungers.

Some interesting details of the 160 horse-power Benz
motor, which is shown at Fig. 246, are reproduced from
the "Aerial Age Weekly," and show how carefully the
design has been considered.

Maximum horse-power, 167.5 B. H. P.

Speed at maximum horse-power, 1,500 E. P. M.

Piston speed .at maximum horse-power, 1,770 ft. per
minute.

Normal horse-power, 160 B. H. P.

Speed at normal horse-power, 1,400 E. P. M.

Piston speed at normal horse-power, 1,656 ft. per
minute.

Brake mean pressure at maximum horse-power, 101.2
pound per square inch.

Brake mean pressure at normal horse-power, 103.4
pound per square inch.

The Benz Motor

555

556 Aviation Engines

Specific power cubic inch swept volume per B. H. P.,
5.46 cubic inch; 160 B. H. P.

Weight of piston, complete with gudgeon pin, rings,
etc., 5.0 pound.

Weight of connecting rod, complete with bearings,
4.99 pound; 1.8 pound reciprocating.

Weight of reciprocating parts per cylinder, 6.8 pound.

Weight of reciprocating parts per square inch of
piston area, 0.33 pound.

Outside diameter of inlet valve, 68 mm.; 2.68 inches.

Diameter of inlet valve port (d), 61.5 mm.; 2.42 inches.

Maximum lift of inlet valve (7&), 11 mm., 0.443 inch.

Area of inlet valve opening (ndh), 21.25 square cm.;
3.29 square inches.

Inlet valve opens, degrees on crank, top dead center.

Inlet valve closes, degrees on crank, 60 late; 35 mm.
late.

Outside diameter of exhaust valve, 68 mm., 2.68 inches.

Diameter of exhaust valve port (cZ), 61.5 mm.; 2!42
inches.

Maximum lift or exhaust valve '(h) 11 mm.; 0.433
inch.

Area of exhaust valve opening (ndJi), 21.25 square
cm.; 3.29 square inches.

Exhaust valve opens, degrees on crank, 60 early;
35 mm. early.

Exhaust valve closes, degrees on crank, 16% late;
5 mm. late.

Length of connecting rod between centers, 314 mm.;
12.36 inches.

Eatio connecting rod to crank throw, 3.49:1.

Diameter of crank-shaft, 56 mm. outside, 2.165 inches;
28 mm. inside, 1.102 inches.

Diameter of crank-pin, 55 mm. outside, 2.165 inches;
28 mm. inside, 1.102 inches.

Diameter of gudgeon pin, 30 mm. outside, 1.181 inches ;
19 mm. inside, 0.708 inch.

Austro-Dcdmler Engine 557

Diameter of cam-shaft, 26 nun. outside, 1.023 inches ;
18 mm. inside, 0.708 inch.

Number of crank-shaft bearings, 7.

Projected area of crank-pin bearings, 36.85 square
cm.; 5.72 square inches.

Projected area of gudgeon pin bearings, 22.20 square
cm.; 3.44 square inches.

Firing sequence, 1, 5, 3, 6, 2, 4.

Type of magnetos, ZH6 Bosch.

Direction of rotation of magneto from driving end,
one clock, one anti-clock.

Magneto timing, full advance? 30 early (16 mm.
early).

Type of carburetors (2) Benz design.

Fuel consumption per hour, normal horse-power, 0.57
pint.

Normal speed of propeller, engine speed, 1,400 E. P. M.

AUSTRO-DAIMLER ENGINE

One of the first very successful European flying engines
which was developed in Europe is the Austro-Daimler,
which is shown in end section in a preceding chapter. The
first of these motors had four-cylinders, 120 by 140 milli-
meters, bore and stroke, with cast iron cylinders, over-
head valves operated by mean's of a single rocker arm,
controlled by two cams and the valves were closed by a
single leaf spring which oscillates with the rocker arm.
The cylinders are cast singly and have either copper or
steel jackets applied to them. The four-cylinder design
was afterwards expanded to the six-cylinder design and
still later -a six-cylinder motor of 130 by 175 millimeters
was developed. This motor uses an offset crank-shaft,
as does the Benz motor, and the effect of offset has been
discussed earlier on in this treatise. The Benz motor also
uses an offset cam-shaft which improves the valve opera-
tion and changes the valve lift diagram. The lubrication
also is different than any other aviation motor, since

558 Aviation Engines

individual high pressure metering pumps are used to
deliver fresh oil only to the bearings and cylinders, as
was the custom in automobile practice some ten years .ago.

SUNBEAM AVIATION ENGINES

These very successful engines have been developed by
Louis Coatalen. At the opening of the war the largest
sized Coatalen motor was 225 horse-power and was of the
L-head type having a single cam-shaft for operating
valves and was an evolution from the twelve-cylinder
racing car which the -Sunbeam Company had previously
built. Since 1914 the Sunbeam Company have produced
engines of six-, eight-, twelve- and eighteen-cylinders from
150 to 500 horse-power with both iron and aluminum
cylinders. For the last two years all the motors have had
overhead cam-shafts with a separate shaft for operating
the intake and exhaust valves. Cam-shafts are connected
through to the crank-shaft by means of a train of spur
gears, all of which are mounted on two double row ball
bearings. In the twin six, 350 horse-power engine, oper-
ating at 2100 E. P. M., requires about 4 horse-power
to operate the cam-shafts. This motor gives 362 horse-
power at 2100 revolutions and has a fuel cousumption of
5 Koo of a pint per brake horse-power hour. The cylinders
are 110 by 160 millimeters. The same design has been
expanded into an eighteen-cylinder which gives 525 horse-
power at 2100 turns. There has also been developed a
very successful eight-cylinder motor rated at 2220 horse-
power which has a bore and stroke of 120 by 130 milli-
meters, weight 450 pounds. This motor is an aluminum
block construction with steel sleeves inserted. Three
valves are operated, one for the inlet and two for the
exhaust. One cam-shaft operates the three valves.

The modern Sunbeam engines operate with a mean
effective pressure of 135 pounds with a compression ratio
of 6 to 1 sea level. The connecting rods are of the articu-
lated type as in the Eenault motor and are very short.

Sunbeam Aviation Engines

559

The weight of these motors turns out at 2.6 pounds per
brake horse-power, and they are able to go through a
100 hour test without any trouble of any kind. The lubri-
cating system comprises a dry base and oil pump for.

Fig. 247. At Top, the Sunbeam Overhead Valve 170 Horse-Power Six-
Cylinder Engine. Below, Side View of Sunbeam 350 Horse-Power
Twelve-Cylinder Vee Engine.

drawing the oil off from the base, whence it is delivered
to the filter and cooling system. It then is pumped by a
separate high pressure gear pump through the entire
motor. In these larger European motors, castor-oil is

560

Aviation Engines

Sunbeam Aviation Engines

561

used largely for lubrication. It is said that without the
use of castor-oil it is impossible to hold full power for
five hours. Coatalen favors aluminum cylinders rather
than cast iron. The series of views in Figs. 247 to 250
inclusive, illustrates the vertical, narrow type of engine;
the V-form; and the broad arrow type wherein three

Fig. 249. Sunbeam Eighteen-Cylinder Motor, Viewed from Pump and

Magneto End.

rows, each of six-cylinders, are set on a common crank-
case. In this water-cooled series the gasoline and oil
consumption are notably low, as is the weight per horse-
power.

In the eighteen-cylinder overhead valve Sunbeam-
Coatalen aircraft engine of 475 brake horse-power, there
are no fewer than half a dozen magnetos. Each magneto
is inclosed. Two sparks are furnished to each cylinder

562-

Aviation Engines

from independent magnetos. On this engine there are
also no fewer than six carburetors. Shortness of crank-
shaft, and therefore of engine length, and absence of
vibration are achieved by the linking of the connecting-
rods. Those concerned with three-cylinders in the broad
arrow formation work on one crank-pin, the outer rods
being linked to the central master one. In consequence

Fig. 250. Propeller End of Sunbeam Eighteen-Cylinder 475 B.H.P.
Aviation Engine.

of this arrangement, the piston travel in the case of the
central row of cylinders is 160 mm., while the stroke of
the pistons of the cylinders set on either side is in each
case 168 mm. Inasmuch as each set of six-cylinders is
completely balanced in itself, this difference in stroke
does not affect the balance of the engine as a whole. The

Indicating Meters 563

duplicate ignition scheme also applies to the twelve-
cylinder 350 brake horse-power Sunbeam- Coatalen over-
head valve aircraft engine type. It is distinguishable,
incidentally, by the passage formed through the center of
each induction pipe for the sparking plug in the center
cylinder of each block of three. In this, as in the eighteen-
cylinder and the six-cylinder types, there are two cam-
shafts, for each set of cylinders. These cam-shafts are
lubricated by low pressure and are operated through a
train of inclosed spur wheels at the magneto end of the
machine. The six-cylinder, 170 brake horse-power vertical
type employs the same general principles, including the
detail that each carburetor serves gas to a group of three-
cylinders only. It will be observed that this engine pre-
sents notably little head resistance, being suitable for
multi-engined aircraft.

INDICATING METERS FOR AUXILIARY SYSTEMS

The proper functioning of the power plant and the
various groups comprising it may be readily ascertained
at any time by the pilot because various indicating meters
and pressure gauges are provided which are located on a
dash or cowl board in front of the aviator, as shown at
Fig. 251. The speed indicator corresponds to the speedom-
eter of an automobile and gives an indication of the speed
the airplane is making, which taken in conjunction" with the
clock will make it possible to determine the distance cov-
ered at a flight. The altimeter, which is an aneroid
barometer, outlines with fair accuracy the height above
the ground at which a plane is flying. These instruments
are furnished to enable the aviator to navigate the air-
plane when in the air, and if the machine is to be used
for cross-country flying, they may be supplemented by a
compass and a drift set. It will be evident that these,
are purely navigating instruments and only indicate the
motor condition in an indirect manner. The best way of
keeping track of the motor action is to watch the tachom-

564

Aviation Engines

Compressed Air-Starting Systems 565

eter or revolution counter which is driven from the
engine by a flexible shaft. This indicates directly the
number of revolutions the engine is making per minute
and, of course, any slowing up of the engine in normal
flights indicates that something is not functioning as it
should. The tachometer operates on the same principle
as the speed indicating device or speedometer used in
automobiles except that the dial is calibrated to show
revolutions per minute instead of miles per hour. At the
extreme right of the dash at Fig. 251 the spark advance
and throttle control levers are placed. These, of course,
regulate the motor speed just as they do in an automobile.
Next to the engine speed regulating levers is placed a
push button cut-out switch to cut out the ignition and
stop the motor. Three pressure gauges are placed' in a
line. The one at the extreme right indicates the pressure
of air on the fuel when a pressure feed system is used.
The middle one shows oil pressure, while that nearest
the center of the dash board is employed to show the air
pressure available in the air starting system. It will be
evident that the character of the indicating instruments
will vary with the design of the airplane. If it was pro-
vided with an electrical starter instead of an air system
electrical indicating instruments would have to be pro-
vided.

COMPRESSED AIR- STARTING SYSTEMS

Two forms of air- starting systems are in general use,
one in which the crank-shaft is turned by means of an
air motor, the other class where compressed air is ad-
mitted to the cylinders proper and the motor turned over
because of the air pressure acting on the engine pistons.
A system known as the "Never-Miss" utilizes a small
double-cylinder air pump is driven from the engine by
means of suitable gearing and supplies air to a substan-
tial container located at some convenient point in the
fuselage. The air is piped from the container to a dash-
control valve and from this member to a peculiar form

566 Aviation Engines

of air motor mounted near the crank-shaft. The air
motor consists of a piston to which a rack is fastened
which engages a gear mounted on the crank shaft pro-
vided with some form of ratchet clutch to permit it to
revolve only in one direction, and then only when the
gear is turning faster than the engine crank-shaft.

The method of operation is extremely simple, the
dash-control valve admitting air from the supply tank
to the top of the pump cylinder. When in the position
shown in cut the air pressure will force the piston and
rack down and set the engine in motion. A variety of
air motors are used and in some the pump and motor may
be the same device, means being provided to change the
pump to an air motor when the engine is to be turned- over.

The "Christensen" air starting system is shown at
Figs. 252 and 253. An air pump is driven by the engine,
and this supplies air to an air reservoir or .container
attached to the fuselage. This container communicates
with the top of an air distributor when a suitable control
valve is open. An air pressure gauge is provided to
enable one to ascertain the air pressure available. The
top of each cylinder is provided with a check valve,
through which air can flow only in one direction, i.e., from
the tank to the interior of the cylinder. Under explosive
pressure these check valves close. The function of the
distributor is practically the same as that of an ignition
timer, its purpose being to distribute the air to the cylin-
ders of the engine only in the proper firing order. All
the while that the engine is running and the car is in
motion the air pump is functioning, unless thrown out of
action by an easily manipulated automatic control. When
it is desired to start the engine a starting valve is opened
which permits the air to flow to the top of the distributor,
and then through a pipe to the check valve on top of the
cylinder about to explode. As the air is going through
under considerable pressure it will move the piston down
just ias the explosion would, and start the engine rotating.
The inside of the distributor rotates and directs a charge

Air-Starting System

567

of air to the cylinder next to fire. In this way the engine
is given a number of revolutions, and finally a charge of
gas will be ignited and the engine start off on its cycle of
operation. To make starting positive and easier some

Fig. 252. Parts of Christensen Air Starting System Shown at A, and
Application of Piping and Check Valves to Cylinders of Thomas-
Morse Aeromotor Outlined at B.

gasoline is injected in with the air so an inflammable mix-
ture is present in the cylinders instead of air only. This
ignites easily and the engine starts off sooner than would
otherwise be the case. The air pressure required varies
from 125 to 250 pounds per square inch, depending upon
the size and type of the engine to be set in motion.

568

Aviation Engines

02
bO

Electric Starting Systems 569

ELECTEIC STARTING SYSTEMS

Starters utilizing electric motors to turn over the
engine have been recently developed, and when properly
made and maintained in an efficient condition they an-'
rfwer all the requirements of an ideal starting device.
The capacity is very high, as the motor may draw cur-
rent from a storage battery and keep the engine turning
over for considerable time on a charge. The objection
against their use is that it requires considerable compli-
cated and costly apparatus which is difficult to under-
stand and which requires the services of an expert electri-
cian to repair should it get out of order, though if bat-
tery ignition is used the generator takes the place of the
usual ignition magneto.

In the Delco system the electric current is generated
by a combined motor-generator permanently geared to
the engine. When the motor is running it turns the
armature and the motor generator is acting as a dynamo,
only supplying current to a storage battery. On account
of the varying speeds of the generator, which are due to
the fluctuation in engine speed, some form of automatic
switch w^hich will disconnect the generator from the bat-
tery at such times that the motor speed is not sufficiently
high to generate a current stronger than that delivered
by the battery is needed. These automatic switches are
the only -delicate part of the entire apparatus, and while
they requir.e very delicate adjustment they seem to per-
form very satisfactorily in practice.

When it is desired to start the engine an electrical
connection is established between the storage battery and
the motor-generator unit, and this acts as a motor and
turns the engine over by suitable gearing which engages
the gear teeth cut into a special gear or disc attached to
the engine crank-shaft. When the motor-generator fur-
nishes current for ignition as well as for starting the
motor, the fact that the current can be used for this work
as well as starting justifies to a certain extent the rather

570 Aviation Engines

complicated mechanism which forms a complete starting
and ignition system, and which may also be used for light-
ing if necessary in night flying.

An electric generator and motor do not complete a
self-starting system, because some reservoir or container
for electric current must be provided. The current from
the generator is usually stored in a storage battery from
which it can be made to return to the motor or to the
same armature that produced it. The fundamental units
of a self-starting system, therefore, are a generator to
produce the electricity, a storage battery to serve as a
reservoir, and an electric motor to rotate the motor crank-
shaft. Generators are usually driven by enclosed gear-
ing, though silent chains are used where the center dis-
tance between the motor shaft and generator shaft is too
great for the gears. An electric starter may be directly
connected to the gasoline engine, as is the case where the
combined motor-generator replaces the fly-wheel in an
automobile engine. The not or may also drive the engine
by means of a silent chain or by direct gear reduction.

Every electric starter must use a switch of some kind
for starting purposes and most systems include an out-
put regulator and a reverse current cut-out. The output
regulator is a simple device that regulates the strength
of the generator current that is supplied the storage bat-
tery. A reverse current cut-out is a form of check
valve that prevents the storage battery from discharging
through the generator. Brief mention is made of electric
starting because such systems will undoubtedly be incor-
porated in some future airplane designs. Battery igni-
tion is already being experimented with.

BATTERY IGNITION SYSTEM PARTS

A battery ignition system in its simplest form consists
of a current producer, usually a set of dry cells or a
storage battery, an induction coil to transform the low
tension current to one having sufficient strength to jump

Battery Ignition System Parts 571

the air gap at the spark-plug, an igniter member placed
in the combustion chamber and a timer or mechanical
switch operated by the engine so that the circuit will be
closed only when it is desired to have a spark take place
in the cylinders. Battery ignition systems may be of two
forms, those in which the battery current is stepped up
or intensified to enable it to jump an air gap between the
points of the spark plug, these being called "high ten-
sion" systems and the low tension form (never used on
airplane motors) in which the battery current is not inten-
sified to a great degree and a spark produced in the cylin-
der by the action of a mechanical circuit breaker in the
combustion chamber. The low tension system is the sim-
plest electrically but the more complex mechanically.
The high tension system has the fewest moving parts but
numerous electrical devices. At the present time all air-
plane engines use high tension ignition systems, the mag-
neto being the most popular at the present time. The
current distribution and timing devices used with modern
battery systems are practically the same as similar parts
of a magneto.

INDEX

Action of Four-cycle Engine 38

Action of Le Ehone Kotary Engine 503

Action of Two-cycle Engine 41

Action of Vacuum Feed System 119

Actual Duration of Different Functions 93

Actual Heat Efficiency 62

Adiabatic Diagram 51

Adiabatic Law . 50

Adjustment of Bearings 449

Adjustment of Carburetors 151

Aerial Motors, Must be Light 20

Aerial Motors, Operating Conditions of 19

Aerial Motors, Requirements of 19

Aeromarine Six-cylinder Engine 527

Aeronautics, Division in Branches 18

Aerostatics 18

Air-cooled Engine Design 229

Air-cooling Advantages 231

Air-cooling, Direct Method .'...: 228

Air-cooling Disadvantages 231

Air-cooling Systems 223-

Aircraft, Heavier Than Air ' 17

Aircraft, Lighter Than Air 18

Aircraft Types, Brief Consideration of 17

Air Needed to Burn Gasoline 113

Airplane Engine, Power Needed 21

Airplane Engines, Overhauling 412

Airplane Engine, How to Time 269

Airplane Engine Lubrication 209

Airplane, How Supported 21

Airplane Motors, German 543

Airplane Motor Types 20

Airplane Motors, Weight of * 21

Airplane Power Plant Installation 324

Airplane Types 18

Airplanes, Horse-power Used in 26

Air Pressure Diminution, With Altitude 144

Altitude, How it- Affects Mixture 153

Aluminum, Use in Pistons 297

573

574 Index

PAGE

American Aviation Engines, Statistics 546

Anzani Badial Engine Installation 344

Anzani Six-cylinder Star Engine 465

Anzani Six-cylinder Water-cooled Engine 459

Anzani Ten- and Twenty-cylinder Engines 468

Anzani Three-cylinder Engine 459

Anzani Three-cylinder Y Type 462

Argus Engine Construction 545

Armature Windings 168

Atmospheric Conditions, Compensating for 143

Austro-Daimler Engine 557

Aviatics 18

Aviation Engine, Aeromarine 527

Aviation Engine, Anzani Six-cylinder Star 465

Aviation Engine, Canton and, Unne 469

Aviation Engine Cooling 219

Aviation Engine, Curtiss 519

Aviation Engine Cylinders 233

Aviation Engine, Early Gnome 472

Aviation Engine, German Gnome Type 495

Aviation Engine, Gnome Monosoupape : 486

Aviation Engine, How To Dismantle 415

Aviation Engine, How to Start 460

Aviation Engine, Le Ehone Rotary 495

Aviation Engine Oiling 218

Aviation Engine Parts, Functions of ; 82

Aviation Engine, Renault Air-cooled 507

Aviation Engine, Stand for Supporting 414

Aviation Engine, Sturtevant 515

Aviation Engine, Thomas-Morse 521

Aviation Engine Types 457

Aviation Engine, Wisconsin 531

Aviation Engines, Anzani Six-cylinder Water-cooled 459

Aviation Engines, Anzani Ten- and Twenty-cylinder 468

Aviation Engines, Anzani Three-cylinder 459

Aviation Engines, Anzani Y Type 462

Aviation Engines, Argus 545

Aviation Engines, Austro-Daimler 557

Aviation Engines, Benz. 551

Aviation Engines, Four- and Six-cylinder 88

Aviation Engines, German 543

Aviation Engines, Hall-Scott 539

Aviation Engines, Hispana-Suiza 512

Aviation Engines, Mercedes 543

Aviation Engines, Overhauling 412

Aviation Engines, Principal Parts of 80

Aviation Engines, Starting Systems For 567

Aviation Engines, Sunbeam 558

Index 575

PAGE

Balanced Crank-shafts 318

Ball-bearing Crank-shaf fs 319

Battery Ignition Systems 571

Baverey Compound Nozzle , 137

Bearings, Adjustment of 449

Bearing Alignment 453

Bearing Brasses, Fitting 450

Bearing Parallelism, Testing 453

Bearing Scrapers and Their Use 446

Benz Aviation Engines 551

Benz Engine Statistics 551

Berling Magneto ...*!" 174

Berling Magneto, Adjustment of 180

Berling Magneto Care 180

Berling Magneto Circuits 176

Berling Magneto, Setting 178

Block Castings 234

Blowing Back 269

Bolts, Screwing Down 452

Bore and Stroke Eatio 240

Boyles Law 49

Brayton Engine 48

Breaker Box, Adjustment of 180

Breast and Hand Drills 387

Burning Out Carbon Deposits 421

Bushings, Camshaft, Wear in 456

Calipers, Inside and Outside 398

Cam Followers, Types of 260

Cams for Valve Actuation 259

Cam-shaft Bushings 456

Cam-shaft Design 313

Cam-shaft Drive Methods .' 261

Cam-shaft Testing 451

Cam-shafts and Timing Gears 456

Canton and Unne Engine 469

Carbon, Burning out with Oxygen 421

Carbon Deposits, Cause of 418

Carbon Eemoval 419

Carbon Scrapers, How Used 420

Carburetion Principles 112

Carburetion System Troubles 355

Carburetor, Claudel ..." 127

Carburetor, Compound Nozzle Zenith 135

576 Index

PAGB

Carburetor, Concentric Float and Jet Type 125

Carburetor, Duplex Zenith 138

Carburetor, Duplex Zenith, Trouble in 357

Carburetor Installation, In Airplanes 148

Carburetor, Le Rhone , 501

Carburetor, Master Multiple Jet , 133

Carburetor, Schebler 125

Carburetor Troubles, How to Locate 354

Carburetor, Two Stage 131

Carburetor, What it Should Do 114

Carburetors, Float Feed . ^ 122

Carburetors, Multiple Nozzle 130

Carburetors, No*es on Adjustment 151

Carburetors, Reversing Position of 149

Carburetors, Spraying 120

Care of Dixie Magneto 188

Castor Oil, for Cylinder Lubrication 205

Castor Oil, Why Used In Gnome Engines 211

Center Gauge 403

Chisels, Forms of 384

Christensen Air Starting System 567

Circuits, Magnetic 161

Classification of Engines 458

Claudel Carburetor 127

Cleaning Distributor 180

Clearances Between Valve Stem and Actuators 261

Combustion Chamber Design 239

Combustion Chambers, Spherical 76

Common Tools, Outfit of 378

Comparing Two-cycle and Four-cycle Types 44

Compound Cam Followers 260

Compound Piston Rings. 301

Compressed Air Starting System 565

Compression, Factors Limiting 69

Compression, in Explosive Motors, Value of 68

Compression Pressures, Chart for 72

Compression Temperature 71

Computations for Horse-power Needed 25

Computations for Temperature 52

Concentric Piston Ring 299

Concentric Valves 255

Connecting Rod Alignment, Testing 454

Connecting Rod, Conventional 308

Connecting Rod Forms 305

Connecting Rod, Gnome Engine 305

Connecting Rods, Fitting 449

Connecting Rods for Vee Engines 310

Connecting Rods, Le Rhone 498

Index 577

PAGE

Connecting Rods, Master 310

Constant Level Splash System 215

Construction of Dixie Magneto '. 186

Construction of Pistons 288

Conversion of Heat to Power '...., 58

Cooling by Air 223

Cooling by Positive Water Circulation 224

Cooling, Heat Loss in 66

Cooling System Defects 358

Cooling Systems Used 223

Cooling Systems, Why Needed 219

Cotter Pin Pliers 384

Crank-case, Conventional 320

Crank-case Forms 320

Crank-case, Gnome 323

Crank-shaft, Built Up 315

Crank-shaft Construction 315

Crank-shaft Design 315

Crank-shaft Equalizer 449

Crank-shaft Form 315

Crank-shaft, Gnome Engine : 483

Crank-shafts, Balanced 318

Crank-shafts, Ball Bearing 319

Cross Level 403

Crude Petroleum, Distillates of Ill

Curtiss Aviation Engines 519

Curtiss Engine Installation 328

Curtiss Engine Repairing Tools 408

Cutting Oil Grooves 448

Cylinder Blocks, Advantages of 237

Cylinder Block, Duesenberg 235

Cylinder Castings, Individual 234

Cylinder Construction 233

Cylinder Faults and Correction 416

Cylinder Form and Crank-shaft Design 238

Cylinder Head Packings 417

Cylinder Head, Eemovable 239

Cylinder, I Head Form 248

Cylinder, L Head Form 248

Cylinder Oils 206

Cylinder Placing 20

Cylinder Placing in V Motor 99

Cylinder Retention, Gnome 475

Cylinder, T Head Form 248

Cylinders, Cast in Blocks 235

Cylinders, Odd Number in Rotary Engines 482

Cylinders, Repairing Scored 423

Cylinders, Valve Location in ; 245

578 Index

PAGE

Defects in Cylinders 417

Defects in Dry Battery 373

Defects in Fuel System 354

Defects in Induction Coil 373

Defects in Magneto 372

Defects in Storage Battery 372

Defects in Timer ! 373

Defects in Wiring and Eemedies . . . 373

Die Holder , 394

Dies for Thread Cutting , 395

Diesel Motor Cards 67

Diesel System 144

Direct Air Cooling 228

Dirigible Balloons 18

Dismantling Airplane Engine 415

Distillates of Crude Petroleum Ill

Division of Circle in Degrees 268

Dixie Ignition Magneto 184

Dixie Magneto, Care of 188

Draining Oil From Crank-case 214

Drilling Machines 386

Drills, Types and Use 388

Driving Cam-shaft, Methods of 262

Dry Cell Battery, Defects in 373

Duesenberg Sixteen Valve Engine 525

Duesenberg Valve Action 255

Duplex Zenith Carburetor 138

Early Gnome Motor, Construction of 472

Early Ignition Systems 155

Early Types of Gas Engine 28

Early Vaporizer Forms 120

Eccentric Piston Eing 299

Economy, Factors Governing 64

Efficiency, Actual Heat 62

Efficiency, Maximum Theoretical 61

Efficiency, Mechanical .' 62

Efficiency of Internal Combustion Engine 60

Efficiency, Various Measures of 61

Eight-cylinder Engine 95

Eight-cylinder Timing Diagram , 276

Electricity and Magnetism, Relation of 162

Electrical Ignition Best 156

Electric Starting Systems 569

Engine, Advantages of V Type 95

Index 579

Engine Base Construction 319

Engine Bearings, Adjusting 443

Engine Bearings, Refitting 442

Engine Bed Timbers, Standard 330

Engine, Four-cycle, Action of .' .- 38

Engine, Four-cycle, Piston Movements in 40

Engine Functions, Duration of : 93

Engine Ignition, Locating Troubles 353

Engine Installation, Gnome . . . . . 344

Engine Installation, Anzani Radial t 344

Engine Installation, Hall-Scott 332

Engine Installation, Rotary 342

Engine Operation, Sequence of 84

Engine Parts and Functions 80

Engine Starts Hard, Ignition Troubles Causing 369

Engine Stoppage, Causes of 347

Engine Temperatures 221

Engine Trouble Charts 369

Engine Troubles, Cooling 358

Engine Troubles, Hints For Locating : 345

Engine Troubles, Ignition 353

Engine Troubles, Noisy Operation 359

Engine Troubles, Oiling 357

Engine Troubles Summarized 350

Engine, Two-cycle, Action of 41

Engines, Classification of 458

Engines, Cylinder Arrangement 31-32

Engines, Eight-cylinder V 95

Engines, Four-cylinder Forms 88

Engines, Graphic Comparison of 33-34-35

Engines, Internal Combustion, Types of 30

Engines, Multiple Cylinder, Power Delivery in 91

Engines, Multiple Cylinder, Why Best .....' 83

Engines, Rotary Cylinder 107

Engines, Six-cylinder Forms 88

.Engines, Twelve-cylinder 96

Equalizer, Crank-shaft 449

Exhaust Closing 270

Exhaust Valve Design, Early Gnome 475

Exhaust Valve Opening 270

Explosive Gases, Mixtures of 56

Explosive Motors, Inefficiency in 74

Explosive Motors, Why Best 27

Factors Governing Economy 64

Eactors Limiting Compression '. . 70

Faults in Ignition 352

580 Index

PAGE

Figuring Horse-power Needed 21

Files, Use and Care of 383

First Law of Gases 49

Fitting Bearings By Scraping 447

Fitting Brasses '. . . . . 450

Fitting Connecting Eods 449

Fitting Main Bearings 448

Fitting Piston Eings 439

Float Feed Carburetor Development 124

Float Feed Carburetors 122

Force Feed Oiling System 218

Forked Connecting Eods 310

Four-cycle Engine, Action of ' 38

Four-cycle Engine, Why Best 45

Fourteen-cylinder Engine 474

Four Valves Per Cylinder 284

Friction, Definition of . 302

Fuel Feed By Gravity 116

Fuel Feed by Vacuum Tank 117

Fuel Storage and Supply 116

Fuel Strainers, Types of 141

Fuel Strainers, Utility of 140

Fuel . System Faults 354

Fuel System Installation, Hall-Scott 336

Fuel System, Gnome 490

Fuel Utilization Chart . 62

Gas Engine, Beau de Eocha 'a Principles 59

Gas Engine Development 28

Gas Engine, Early Forms of 48

Gas Engine, Inventors of 29

Gas Engine, Theory of 47

Gases, Compression of t * 49

Gases, First Law of ^ 49

Gases, Second Law of 50

Gaskets, How to Use 452

Gasoline, Air Needed to Burn 113

Gas Engines, Parts of 80

Gas Vacuum Engine, Brown 's 28

German Airplane Motors 543

German Gnome Type Engine 495

Gnome Aviation Engine, Early Form 472

Gnome Crank-shaft 483

Gnome Cylinder, Machining 489

Gnome Cylinder Eetention 475

Gnome Engine, Fuel^ Lubrication and Ignition 490

Index 581

Gnome Engine, German Type 495

Gnome Engine Installation 344

Gnome Firing Order . . . * 482

Gnome Fourteen-Cylinder Engine .' . 474

Gnome Fourteen-cylinder Engine Details 480

Gnome Monosoupape, How to Time 278

Gnome Monosoupape Type Engine 486

Graphic Comparison of Engine Types 33-34-35

Graphic Comparison, Two- and Four-cycle 46

Gravity Feed System '. 116

Grinding Valves 429

Hall-Scott Aviation Engines 539

Hall-Scott Engine Installation 332

Hall-Scott Engine, Preparations For Starting '341

Hall-Scott Engine- Tools 410

Hall-Scott Lubrication System 211

Hall-Scott Statistic Sheet 544

Heat and Its Work 54

Heat in Gas Engine Cylinder 69

Heat Given to Cooling Water 78

Heat Loss, Causes of 74

Heat Loss in Airplane' Engine 221

Heat Loss in Wall Cooling 65

High Altitude, How it Affects Power 144

High Tension Magneto 172

Hints For Locating Engine Troubles 345

Hints for Starting Engine 361

Hispana-Suiza Model A Engine 512

Horse-power Needed in Airplane 21

Horse-power Needed, How Figured 22

How An Engine is Timed : 277

Ignition, Electric 156

Ignition, Elements of 157

Ignition of Gnome Engine 490

Ignition System, Battery 571

Ignition Systems, Early 155

Ignition System Faults 352

Ignition, Time of 273

Ignition, Two Spark 196

I Head Cylinders -. 248

Improvements in Gas Engines 29

Indicating Meters, Engine Speed 563

582 Index

PAGE

Indicating Meters, Oil and Air Pressure 563

Indicator Cards, How To Eead 66

Indicator Cards, Value of 66

Individual Cylinder Castings 234

Induction Coil, Defects in 373

Inefficiency, Causes of 74

Inlet Valve Closing ' 272

Inlet Valve Opening 270

Installation, Airplane Engine 324

Installation, Curtiss OX 2 Engine 328

Installation, Hall-Scott Engine 332

Installation of Eotary Engines 342

Intake Manifold Construction 143

Intake Manifold Design 142

Internal Combustion Engine, Efficiency of 60, 62

Internal Combustion Engines, Main Types of 30

Inverted Engine Placing -. 325

Isothermal Diagram 51

Isothermal Law . 48

Keeping Oil Out of Combustion Chamber 303

Knight Sleeve Valves ..266

Lag and Lead, Explanation of 268

Lapping Crank-pins 445

Lead Given Exhaust Valve 270

Leak Proof Piston Eings ...... * 301

Lenoir Engine Action 48

Le Ehone Cams and Valve Actuation 500

Le Ehone Carburetor 501

Le Ehone Connecting Eod Assembly, Distinctive , 498

Le Ehone Engine Action 503

Le Ehone Eotary Engine 495

L Head Cylinders 248

Liquid Fuels, Properties of 110

Locating Carburetor Troubles 354

Locating Engine Troubles 350

Locating Ignition Troubles .. . . .^ . 353

Locating Oiling Troubles 357

Location of Magneto Trouble 181

Losses in Wall Cooling 65

Lost Power and Overheating, Summary of Troubles Causing 363

Lubricants, Derivation of 204

Lubricants, Eequirements of 204

Index 588

PAGE

Lubricating System Classification 208

Lubricating Systems, Selection of .' 208

Lubrication By Constant Level Splash System 215

Lubrication By Dry Crank-case Method 218

Lubrication By Force Feed Best 218

Lubrication of Magneto 180

Lubrication System, Gnome 490

Lubrication System, Hall-Scott 211

Lubrication System, Thomas-Morse '. . 210

Lubrication, Theory of 202

Lubrication, Why Necessary 201

Magnetic Circuits 161

Magnetic Influence Defined 158

Magnetic Lines of Force 161

Magnetic Substances 158

Magnetism, Flow Through Armature 166

Magnetism, Fundamentals of 157

Magnetism, Eelation to Electricity 162

Magneto, Action of High Tension 173

Magneto Armature Windings 168

Magneto, Basic Principles of 163

Magneto" Berling 174

Magneto, Defects in .-. 372

Magneto Distributor, Cleaning 180

Magneto Ignition Systems 169

Magneto Ignition Wiring 179

Magneto Interrupter, Adjustment of 180

Magneto, Low Voltage 168

Magneto, Lubrication of 180

Magneto Maintenance 180

Magneto, Method of Driving 175

Magneto Parts* and Functions 167

Magneto, The Dixie 184

Magneto Timing '. 179

Magneto, Timing Dixie 188

Magneto, Transformer System .. . . 171

Magneto Trouble, Location of 181

Magneto, True High Tension 172

Magneto, Two Spark Dual 177

Magnets, Forms of ' 160

Magnets, How Produced 162

Magnets, Properties of 159

Main Bearings, Fitting 448

Manifold, Intake 143

Master Multiple Jet Carburetor ." . 133

584 Index

PAGE

Master Rod Construction 310

Maximum Theoretical Efficiency 61

Meaning of Piston Speed 241

Measures of Efficiency 61

Measuring Tools 397

Mechanical Efficiency \ 62

Mercedes Aviation Engine 543

Metering Pin Carburetor, Stewart 128

Micrometer Caliper, Eeading 405

Micrometer Calipers, Types and Use 404

Mixture, Effect of Altitude on 153

Mixture, Proportions of 151

Mixture, Starvation of 149

Monosoupape Gnome Engine 486

Mother Eod, Gnome Engine 305

Motor Misfires, Carburetor Faults Causing 374

Motor Misfires, Ignition Troubles Causing 370 '

Motor Eaces, Carburetor Faults Causing 374 1

Motor Starts Hard, Carburetor Faults Causing -.- 374 '

Motor Stops In Flight, Carburetor Faults 374

Motor Stops Without Warning, Ignition Troubles 370

Multiple Cylinder Engine, Why Best 83

Multiple Nozzle Vaporizers 129

Multiple Valve Advantages 286

Noisy Engine Operation, Causes of 359

Noisy Operation, Carburetor Faults Causing 374

Noisy Operation, Summary of Troubles Causing 365

Off-set Cylinders, Eeason for 243

Oil Bi-pass, Function of 213 *

Oil, Draining From Crank-case 214

Oil Grooves, Cutting 448

Oil Pressure in Hall-Scott System 214

Oil Pressure Eelief Bi-pass 213

Oiling System Defects . >57

Oils for Cylinder Lubrication 206

Oils for Hall-Scott Engine 215

Oils for Lubrication 204

Operating Principles of Engines 37

Oscillating Pist.on Pin 295

Otto Four-cycle Cards 67

Overhauling Aviation Engines 412

Overhead Cam-shaft Location 252

Overheating, Causes of 359

Index 585

PAGE

Panhard Concentric Valves 255

Petroleum, Distillates of Ill

Piston, Differential 291

Piston Pin Eetention 293

Piston Ring Construction 298

Piston Eing Joints ' 299

Piston Eing Manipulation 438

Piston Eing Troubles 437

Piston Rings, Compound 301

Piston Eings, Concentric 299

Piston Eings, Eccentric , . 299

Piston Eings, Fitting 439

Piston Eings, Leak Proof 301

Piston Eings, Eeplacing 441

Piston Speed in Airplane Engines 241

Piston Speed, Meaning of .' ..: 241

Piston Troubles and Eemedies 436

Pistons, Aluminum 296

Pistons, Details of 288

Pistons for Two-cycle Engines 289

Positive Valve Systems 283

Power, Affected by High Altitude 145

Power Delivery in Multiple Cylinder Engines 91

Power, How Obtained From Heat ' 58

Power Needed in Airplane Engines 21

Power Used in Airplanes 26*

Precautions in Assembling Parts 452

Pressure Belief Fitting 213

Pressures and Temperatures 63

Principles of Carburetion 112

Principles of Magneto Action 163

Properties of Cylinder Oils 207

Properties of Liquid Fuels 110

Pump Circulation Systems 226

Pump Forms /....'. 226

Eadial Cylinder Arrangement . 103

Eeading Indicator Cards 67

Eeamers, Types and Use 392

Eeassembling Parts, Precautions in 451

Eemovable Cylinder Head 239

Renault Air Coded Engine 507

Renault Engine Details 508

Repairing Scored Cylinders 423

Requisites for Best Power Effect 59

586 Index

PAGE

Reseating and Truing Valves 426

Resistance, Influence of 22

Rotary Cylinder Engines 107

Rotary Engine, Le Rhone 495

Rotary Engines, Castor Oil for 211

Rotary Engines, Installing 342

Rotary Engines, Why Odd Number of Cylinders 109

Rotary Engines, Why Odd Number of Cylinders Is Used 482

S. A. E. Engine Bed Dimensions 330

Salmson Nine-cylinder Engine 470

Scissors Joint Rods 310

Scored Cylinders, Repairing '. 422

Scrapers, Types of Bearing 446

Scraping Bearings to Fit . .- 447

Second Law of Gases 50

Sequence of Engine Operation 84

Shebler Carburetor 125

Six-cylinder Timing Diagram 275

Sixteen Valve Duesenberg Engine 525

Skipping or Irregular Operation, Causes of 367

Sliding Sleeve Valves 266

Spark Plug Air Gaps, Setting ; 197

Spark Plug, Design of 193

Spark Plug, Mica 194

Spark Plug, Porcelain 193

Spark Plugs, Defects in 371

Spark Plugs for Two Spark Ignition : 197

Spark Plug, Special for Airplane Engine 199

Spark Plug, Standard S. A. E. . 195

Spherical Combustion Chambers 76

Splash Lubrication 215

Split Pin Remover 384

Spraying Carburetors 120

Springiest Valves 280

Springs, for Valves 263

Spring Winder . 384

Sprung Cam-shaft, Testing 451

Stand for Supporting Engine 414

Starting Engine, Hints for 361

Starting Hall-Scott Engine 341

Starting System, Christensen 567

Starting Systems, Compressed Air . -. 565

Starting Systems, Electric 569

Statistics, American Engines ' 546, 547

Statistic Sheet, Hall-Scott Engines 544

Index 587

Statistics of Benz Engine 551

Steam Engine, Efficiency of 59

Steam Engine, Why Not Used 27

Steel Scale, Machinists ' 399

Stewart Metering Pin Carburetor 128

Storage Battery, Defects in 372

Stroke and Bore Eatio 240

Sturtevant Model 5A Engine 515

Summary of Engine Types 30

Sunbeam Aviation Engines : 588

Sunbeam Eighteen-Cylinder Engine 561

Tap and Die Sets 397

Taps for Thread Cutting , 394

Tee Head Cylinders 247

Temperature Computations * 52

Temperatures and Explosive Pressures 64

Temperatures and Pressures 63

Temperatures, Operating '.'.'.". ; . . 221

Testing Bearing Parallelism 453

Testing Connecting Eod Alignment 454

Testing Fit of Bearings 446

Testing Sprung Cam-shaft ' 451

Theory of Gas Engine 47

Theory of Lubrication 203

Thermo-syphon Cooling System 227

Thomas-Morse Aviation Engine 521

Thomas-Morse Lubrication System 210

Thread Pitch Gauge 403

Time of Ignition 273

Timer, Defects in 373

Times of Explosion 56

Timing Dixie Magneto 188

Timing Gears, Effects of Wear 456

Timing Magneto 179

Timing Valves 267

Tool Outfits, Typical 408

Tools for Adjusting and Erecting '. 378

Tools for Bearing Work 445

Tools for Curtiss -Engines 408

Tools for Grinding Valves 430

Tools for Hall-Scott Engines 410, 411

Tools for Measuring 397

Tools for Eeseating Valves * 426

Trouble in Carburetion System 355

Trouble, Location of Magneto 181

588 Index

PAGE

Troubles, Engine, How to Locate 345

Troubles, Ignition 353

Troubles in Oiling System 357

True High Tension Magneto 172

Twelve-Cylinder Engines 96

Two- and Four-Cycle Types, Comparison of 44

Two-Cycle Engine Action 41

Two-Cycle Three-Port Engine 43

Two-Cycle Two-Port Engine 42

Two-Spark Ignition 196

Two-Stage Carburetor 131

Types of Aircraft 17

Types of Internal Combustion Engines 30

Vacuum Fuel Feed, Stewart 119

Value of Compression 69

Value of Indicator Cards 66

Valve Actuation, Le Rhone 500

Valve Design and Construction 256

Valve-Grinding Processes 429

Valve-Lifting Cams 259

Valve-Lifting ^lungers 260

Valve Location Practice 245

Valve Operating Means 252

Valve Operating System, Depreciation in 433

Valve Operation 258

Valve Eemoval and Inspection 424

Valve Seating, How to Test 432

Valve Springs 263

Valve Timing, Exhaust 270

Valve Timing, Gnome Monosoupape * 278

Valve Timing, Intake 270

Valve Timing, Lag and Lead 269

Valve Timing Proceedure 277

Valve Timing Practice 267

Valves, Electric Welded 258

Valves, Flat and Bevel Seat 257

Valves, Four per Cylinder 284

Valves, How Placed in Cylinder 247

Valves in Cages 249

Valves in Removable Heads 249

Valves, Materials Used for 258

Valves, Reseating . . .. 426

Vaporizer, Simple Forms of 120

V Engines, Cylinder Arrangement in 102

Vernier, How Used .401

Index 589

PAGE

Wall Cooling, Losses in 65

Water Cooling by Natural Circulation 227

Water Cooling System , 224

Weight of Airplane Motors 21

Wiring, Defects in 373

Wiring Magneto Ignition System 179

Wisconsin Engines 531

Wrenches, Forms of 380

Wristpin Retention 293

Wristpin Retention Locks 295

Wristpin Wear and Remedy 442

Zenith Carburetor, Action of 137

Zenith Duplex Carburetor, Troubles in 356

Zenith Carburetor Installalion 139

CATALOGUE

Of the LATEST and BEST

PRACTICAL and MECHANICAL

BOOKS

Including Automobile and Aviation Books

Any of these books will be sent prepaid to any part of the world,

on receipt of price. Remit by Draft, Postal Order, Express

Order or Registered Letter

Published and For Sale By

The Norman W. Henley Publishing Co.,

2 West 45th Street, New York, U.S.A.

THE NORMAN W. HENLEY PUBLISHING CO.

INDEX

PAGES

Air Brakes 21, 24

Arithmetic 14, 25, 31

Automobile Books 3, 4, 5, 6

Automobile Charts 6, 7

Automobile Ignition Systems 5

Automobile Lighting 5

Automobile Questions and Answers 4

Automobile Repairing 4

Automobile Starting Systems 5

Automobile Trouble Charts 5, 6

Automobile Welding 5

Aviation 7

Aviation Chart. 7

Batteries, Storage 5

Bevel Gear 19

Boiler-Room Chart 9

Brazing 7

Cams 19

Carburetion Trouble Chart 6

Change Gear -. 19

Charts 6, 7, 8

Coal 22

Coke 9

Combustion 22

Compressed Air 10

Concrete 10, 11, 12

Concrete for Farm Use 11

Concrete for Shop Use. 11

Cosmetics 27

Cyclecars 5

Dictionary 12

Dies 12,13

Drawing 13, 14

Drawing for Plumbers 28

Drop Forging. 13

Dynamo Building 14

Electric Bells 14

Electric Switchboards 14, 16

Electric Toy Making 15

Electric Wiring .' 14, 15, 16

Electricity 14, 15, 16, 17

Encyclopedia 24

E-T Air Brake 24

Every-day Engineering 34

Factory Management 17

Ford Automobile 3

Ford Trouble Chart 6

Formulas and Recipes , 29

Fuel 17

Gas Construction 18

Gas Engines 18, 19

Gas Tractor 33

Gearing and Cams 19

Glossary of Aviation Terms 7,12

Heating : 31, 32

Horse-Power Chart. 9

Hot-Water Heating , .31, 32

House Wiring 15, 17

How to Run an Automobile 3

Hydraulics 5

Ice and Refrigeration 20

Ignition Systems 5

Ignition-Trouble Chart 6

India Rubber 30

Interchangeable Manufacturing 24

Inventions 20

Knots 20

Lathe Work... , . 20

PAGES

Link Motions 22

Liquid Air 21

Locomotive Boilers 22

Locomotive Breakdowns 22

Locomotive Engineering 21, 22, 23, 24

Machinist Book 24, 25, 26

Magazine, Mechanical 34

Manual Training 26

Marine Engineering 26

Marine Gasoline Engines 19

Mechanical Drawing 13, 14

Mechanical Magazine 34

Mechanical Movements 25

Metal Work 12, 13

Motorcycles 5, 6

Patents 20

Pattern Making 27

Perfumery 27

Perspective 13

Plumbing 28, 29

Producer Gas 19

Punches 13

Questions and Answers on Automobile 4

Questions on Heating 32

Railroad Accidents 23

Railroad Charts 9

Recipe Book 29

Refrigeration 20

Repairing Automobiles 4

Rope Work 20

Rubber 30

Rubber Stamps 30

Saw Filing 30

Saws, Management of . . ., 30

Sheet-Metal Works 12, 13

Shop Construction 25

Shop Management 25

Shop Practice 25

Shop Tools 25

Sketching Paper t 14

Soldering 7

Splices and Rope Work 20

Steam Engineering 30, 31

Steam Heating 31, 32

Steel 32

Storage Batteries -5

Submarine Chart 9

Switchboards 14, 16

Tapers 21

Telegraphy, Wireless 17

Telephone 16

Thread Cutting 26

Tool Making 24

Toy Making 15

Train Rules 23

Tractive Power Chart 9

Tractor, Gas 33

Turbines 33

Vacuum Heating. 32

Valve Setting 22

Ventilation ' 31

Watch Making 33

Waterproofing 12

Welding with Oxy-acetylene Flame 5, 33

Wireless Telegraphy : . 17

Wiring... 14, 15

Wiring Diagrams 14

Any of these books promptly sent prepaid to any address in
the world on receipt of price.

HOW TO REMIT By Postal Money Order, Express Money Order,
Bank Draft or Registered Letter.

CATALOGUE OF GOOD, PRACTICAL BOOKS

AUTOMOBILES AND MOTORCYCLES

The Modern Gasoline Automobile Its Design, Construction, and Opera-
tion, 1918 Edition. By VICTOR W. PAGE, M.S.A.E.

This is the most complete, practical and up-to-date treatise on gasoline automobiles and their
component parts ever published. In the new revised and enlarged 1918 edition, all phases of
automobile construction, operation and maintenance are fully and completely described, and
in language anyone can understand. Every part of all types of automobiles, from light cycle-
cars to heavy motor trucks and tractors, are described in a thorough manner, not only
the automobile, but every item of it; equipment, accessories, tools needed, supplies and spare
parts necessary for its upkeep, are fully discussed.

It is dearly and concisely written by an expert familiar with every branch of the automobile industry
and the originator of the practical system of self-education on technical subjects. It is a liberal edu-
cation in the automobile art, useful to all who motor for either business or pleasure.
Anyone reading the incomparable treatise is in touch with all improvements that have been
made in motor-car construction. All latest developments, such as high speed aluminum motors
and multiple valve and sleeve-valve engines, are considered in detail. The latest ignition,
carburetor and lubrication practice is outlined. New forms of change speed gears, and final
power transmission systems, and all latest chassis improvements are shown and described.
This book is used in all leading automobile schools and is conceded to be the STANDARD
TREATISE. The chapter on Starting and Lighting Systems has been greatly enlarged, and
many automobile engineering features that have long puzzled laymen are explained so clearly
that the underlying principles can be understood by anyone. This book was first published
six years ago and so much new matter has been added that it is nearly twice its original size.
The only treatise covering various forms of war automobiles and recent developments in motor-
truck design as well as pleasure cars. This book is not too technical for the layman nor too elementary
for the more expert. It is an incomparable work of reference for home or school. 1,000 6x9 pages,
nearly 1,000 illustrations, 12 folding plates. Cloth bound. Price , . . . .$3.00

WHAT IS SAID OF- THIS BOOK:

" It is the best book on the Automobile seen up to date." J. H. Pile, Associate Editor Auto-
mobile Trade Journal.

"Every Automobile Owner has use for a book of this character." The Tradesman.
"This book is superior to any treatise heretofore .published on the subject." The Inventive Age.
" We know of no other volume that is so complete in all its departments, and in which the wide
field of automobile construction with its mechanical intricacies is so plainly handled, both in
the text and in the matter of illustrations." The Motorist.

"The book is very thorough, a careful examination failing to disclose any point in connection
with the automobile, its care and repair, to have been overlooked." Iron Age.
"Mr. Page has done a great work, and benefit to the Automobile Field." W. C. Hasford,
Mgr. Y. M. C. A-. Automobile School, Boston, Mass.

"It is just the kind of a book a motorist needs if he wants to understand his car." American
Thresherman.

The Model T Ford Car, Its Construction, Operation and Repair. By VICTOR
W. PAGE, M.S.A.E.

This is a complete instruction book. All parts of the Ford Model T Car are described and
illustrated; the construction is fully described and operating principles made clear to everyone.
Every Ford owner needs this practical book. You don't have to guess about the construction
or where the trouble is, as it shows how to take all parts apart and how to locate and fix all
faults. The writer, Mr. Pag6, has operated a Ford car for many years and writes from actual
knowledge. Among the contents are: 1. The Ford Car: Its Parts and Their Functions.
2. The Engine and Auxiliary Groups. How the Engine Works The Fuel Supply System
The Carburetor Making the Ignition Spark Cooling and Lubrication. 3. Details of Chassis.
Change Speed Gear Power Transmission Differential Gear Action Steering Gear Front
Axle Frame and Springs Brakes. 4. How to Drive and Care for the Ford. The Control
System Explained Starting the Motor Driving the Car Locating Roadside Troubles
Tire Repairs Oiling -the Chassis Winter Care of Car. 5. Systematic Location of Troubles
and Remedies. Faults in Engine Faults in Carburetor Ignition Troubles Cooling and
Lubrication System Defects Adjustment of Transmission Gear General Chassis Repairs.
95 illustrations, 300 pages, 2 large folding plates. Price $1.00

How to Run an Automobile. By VICTOR W. PAGE, M.S.A.E.

This treatise gives concise instructions for starting and running all makes of gasoline auto-
mobiles, how to care for them, and gives distinctive features of control. Describes every
step for shifting gears, controlling engines, etc. Among the chapters contained are: I.
Automobile Parts and Their Functions. II. General Starting and Driving Instructions.
III. Typical 1917 Control Systems. IV. Care of Automobiles. 178 pages. 72 specially
made illustrations. Price $1.00

4 THE NORMAN W. HENLEY PUBLISHING CO.
Automobile Repairing Made Easy. By VICTOR W. PAGE, M.S.A.E.

A comprehensive, practical exposition of every phase of modern automobile repairing prac-
tice. Outlines every process incidental to motor car restoration. Gives plans for workshop
construction, suggestions for equipment, power needed, machinery and tools necessary to
carry on business successfully. Tells how to overhaul and repair all parts of all auto-
mobiles. Everything is explained so simpy that motorists and students can acquire a full
working knowledge of automobile repairing. This work starts with the engine, then considers
carburetion, ignition, cooling and lubrication systems. The clutch, change speed gearing
and transmission system are considered in detail. Contains instructions for repairing all
types of axles, steering gears and other chassis parts. Many tables, short cuts in figuring
and rules of practice are given for the mechanic. Explains fully valve and magneto timing,
"tuning" engines, systematic location of trouble, repair of ball and roller bearings, shop kinks,
first aid to injured and a multitude of subjects of interest to all in the garage and repair business.
This book contains special instructions on electric starting, lighting and ignition systems, tire
repairing and rebuilding, autogenous welding, brazing and soldering, heat treatment of steel, latest
timing practice, eight and twelve-cylinder motors, etc. 5%x8. Cloth. 1,056 pages, 1,000 illus-
trations, 11 folding plates. Price $3.00

WHAT IS SAID OF THIS BOOK:

'"Automobile Repairing Made Easy' is the best book on the subject I have ever seen and
the only book I ever saw that is of any value in a garage." Fred Jeffrey, Martinsburg, Neb.
"I wish to thank you for sending me a copy of 'Automobile Repairing Made Easy.' I do
not think it could be excelled." S. W. Gisriel, Director of Instruction, Y. M. C. A., Phila-
delphia, Pa.

Questions and Answers Relating to Modern Automobile Construction,
Driving and Repair. By VICTOR W. PAGE, M.S.A.E.

A practical self-instructor for students, mechanics and motorists, consisting of thirty-seven
lessons in the form of questions and answers, written with special reference to the require-
ments of the non-technical reader desiring easily understood, explanatory matter relating
to all branches of automobiling. The subject-matter is absolutely correct and explained in
simple language. If you can't answer all of the following questions, you need this work. The
answers to these and over 2,000 more- are to be found in its pages. Give the name of all im-
portant parts of an automobile and describe their functions. Describe action of latest types
of kerosene carburetors. What is the difference between a "double" ignition system and a
"dual" ignition system? Name parts of an induction coil. How are valves l-lmed? What
is an electric motor starter and how does it work? What are advantages of worm drive gear-
ing? Name all important types of ball and roller bearings. What is a "three-quarter" float-
ing axle: What is a two-speed axle? What is the Vulcan electric gear shift? Name the causes
of -lost power in automobiles. Describe all noises due to deranged mechanism and give causes t
How can you adjust a carburetor by the color of the exhaust gases? What causes "popping"
in the carburetor? What tools and supplies are needed to equip a car? How do you drive
various makes of cars? What is a differential lock and where is it used? Name different
systems of wire wheel construction, etc., etc. A popular work at a popular price. 5^x7^-
Cloth. 650 pages, 350 illustrations, 3 folding plates. Price $1.50

WHAT IS SAID OF THIS BOOK:

"If you own a car get this book." The Glassworker.

"Mr. Page has the faculty of making difficult subjects plain and understandable." Bristol

Press.

"We can name no writer better qualified to prepare a book of instruction on automobiles

than Mr. Victor W. Pag6." Scientific American.

"The best automobile catechism that has appeared." Automobile Topics.

"There are few men, even with long experience, who will not find this book useful. Great

pains have been taken to make it accurate. Special recommendation must be given to the

illustrations, which have been made specially for the work. Such excellent books as this

greatly assist in fully understanding your automobile." Engineering News.

The Automobilist's Pocket Companion and Expense Record. Arranged by

VICTOR W. PAGE, M.S.A.E.

This book is not only valuable as a convenient cost record but contains much information of value
to motorists. Includes a condensed digest of auto laws of all States, a lubrication schedule,
hints for care of storage battery and care of tires, location of road troubles, anti-freezing
solutions, horse-power table, driving hints and many useful tables and recipes of interest to
all motorists. Not a technical book in any sense of the word, just a collection of practical
facts in simple language for the everyday motorist. Price ...... $1.00

CATALOGUE OF GOOD, PRACTICAL BOOKS 5

Modern Starting, Lighting and Ignition Systems. By VICTOR W. PAGE, M.E.

This practical volume has been written with special reference to the requirements of the non-
technical reader desiring easily understood, explanatory matter, relating to all types of auto-
mobile ignition, starting and lighting systems. It can be understood by anyone, even without
electrical knowledge, because elementary electrical principles are considered before any at-
tempt is made to discuss features of the various systems. These basic principles are clearly
stated and illustrated with simple diagrams. All the leading systems of starting, lighting and
ignition haw been described and illustrated with the co-operation of the experts employed by the
manufacturers. Wiring diagrams are shown in both technical and non-technical forms. All
symbols are fully explained. It is a comprehensive review of modern starting and ignition
system practice, and includes a complete exposition of storage battery construction, care and
repair. All types of starting motors, generators, magnetos, and all ignition or lighting system-
units are fully explained. Every person in the automobile business needs this volume. Among
some of the subjects treated are: I. Elementary Electricity; Current Production; Flow;
Circuits; Measurements; Definitions; Magnetism; Battery Action; Generator Action. II. Battery
Ignition Systems. III. Magneto Ignition Systems. IV. Elementary Exposition of Starting
System Principles. V. Typical Starting and Lighting Systems; Practical Application ; Wiring
Diagrams; Auto-lite, Bijur, Delco, Dyneto-Entz, Gray and Davis, Remy, U. S. L., Westinghouse,
Bosch-Rushmore, Genemotor, North-East, etc. VI. Locating and Repairing Troubles in Start-
ing and Lighting Systems. VII. Auxiliary. Electric Systems; Gear-shifting by Electricity;
Warning Signals; Electric Brake; Entz-Transmission, Wagner-Saxon Circuits, "Wagner-
Studebaker Circuits. 5)^x7^. Cloth. 530 pages, 2J7 illustrations, 3 folding plates.
Price $1.50

Automobile Welding With the Oxy-Acetylene Flame. By M. KEITH DUNHAM.

This is the only complete book on the "why" and "how" of Welding with the Oxy-Acetylene
Flame, and from its pages one can gain information so that he can weld anything that comes
along.

No one can afford to be without this concise book, as it first explains the apparatus to be
used, and then covers in detail the actual welding of all automobile parts. The welding of
aluminum, cast iron, steel, copper, brass and malleable iron is clearly explained, as well
as the proper way to burn the carbon out of the combustion head of the motor. Among the
contents are: Chapter I. Apparatus Knowledge. Chapter II. Shop Equipment and
Initial Procedure. Chapter III. Cast Iron. Chapter IV. Aluminum. Chapter V.
Steel. Chapter VI. Malleable Iron, Copper, Brass, Bronze. Chapter VII. Carbon Burn-
ing and other Uses of Oxygen and Acetylene. Chapter VIII How to Figure Cost of Weld-
ing. 167 pages, fully illustrated. Price $1.00

Storage Batteries Simplified. By VICTOR W. PAG, M.S.A.E.

A comprehensive treatise devoted entirely to secondary batteries and their maintenance,
repair and use.

This is the most up-to-date book on this subject. Describes fully the Exide, Edison, Gould,
Willard, U. S. L. and other storage battery forms in the types best suited for automobile,
stationary and marine work. Nothing of importance has been omitted that the reader should
know about the practical operation and care of storage batteries. No details have been
slighted. The instructions for charging and care have been made as simple as possible. Brief
Synopsis of Chapters: Chapter I. Storage Battery Development; Types of Storage Bat-
teries; .Lead Plate Types; The Edison Cell. Chapter II. Storage Battery Construction;
Plates and Girds; Plante Plates; Faur6 Plates; Non-Lead Plates; Commercial Battery
Designs. Chapter III. Charging Methods; Rectifiers; Converters; Rheostats; Rules
for Charging. Chapter IV. Battery Repairs and Maintenance. Chapter V. Industrial
Application of Storage Batteries; Glossary of Storage Battery Terms. 208 Pages. Very
Fully Illustrated. Price i $1.50 net.

Motorcycles, Side Cars and Cyclecars; their Construction, Management
and Repair. By VICTOR W. PAGE, M.S.A.E.

The only complete work published for the motorcyclist and cyclecarist. Describes fully all
leading types of machines, their design, construction, maintenance, operation and repair.
This treatise outlines fully the operation of two- and four-cycle power plants and all ignition,
carburetion and lubrication systems in detail. Describes all representative types of free
engine clutches, variable speed gears and power transmission systems. Gives complete in-
structions for operating and repairing all types. Considers fully electric self-starting and
lighting systems, all types of spring frames and spring forks and shows leading control methods.
For those desiring technical information a complete series of tables and many formula? to
assist in designing are included. The work tells how to figure power needed to climb grades,
overcome air resistance and attain high speeds. It shows how to select gear ratios for various
weights and powers, how to figure braking efficiency required, gives sizes of belts and chains
to transmit power safely, and shows how to design sprockets, belt pulleys, etc. This work
also includes complete formulae for figuring horse-power, shows how dynamometer tests are

6 THE NORMAN W. HENLEY PUBLISHING CO.

made, defines relative efficiency of air and water-cooled engines, plain and anti-friction bear-
ings and many other data of a practical, helpful, engineering nature. Remember that you
get this information in addition to the practical description and instructions which alone are
worth several times the price of the book. 550 pages. 350 specially made illustrations, 5
folding plates. Cloth. Price $1.50

WHAT IS SAID OF THIS BOOK:

"Here is a book that should be in the cycle repairer's kit." American Blacksmith.

"The best way for any rider to thoroughly understand his machine, is to get a copy of this

book; it is worth many times its price." Pacific Motorcyclist.

AUTOMOBILE AND MOTORCYCLE CHARTS

Chart. Location of Gasoline Engine Troubles Made Easy A Chart Show-
ing Sectional View of Gasoline Engine. Compiled by VICTOR W. PAGE,
M.S.A.E.

It shows clearly all parts of a typical four-cylinder gasoline engine of the four-cycle type.

It outlines distinctly all parts liable to give trouble and also details the derangements apt

to interfere with smooth engine operation.

Valuable to students, motorists, mechanics, repairmen, garagemen, automobile salesmen,

chauffeurs, motorboat owners, motor-truck and tractor drivers, aviators, motor-cyclists,

and all others who have to do with gasoline power plants.

It simplifies location of all engine troubles, and while it will prove invaluable to the novice,

it can be used to advantage by the more expert. It should be on the walls of every public

and private garage, automobile repair shop, club house or school. It can be carried in the

automobile or pocket with ease, and will insure againct loss of time when engine trouble

manifests itself.

This sectional view of engine is a complete review of all motor troubles. It is prepared by a

practical motorist for all who motor. More information for the money than ever before

offered. No details omitted. Size 25x38 inches. Securely mailed on receipt of JJ5 CCntS

Chart. Location of Ford Engine Troubles Made Easy. Compiled by VICTOR

W. PAGE, M.S.A.E.

This shows clear sectional views depicting all portions of the Ford power plant and auxiliary
groups. It outlines clearly all parts of the engine, fuel supply system, ignition group and
cooling system, that are apt to give trouble, detailing all derangements that are liable to
make an engine lose power, stact hard or work irregularly. This chart is valuable to students,
owners, and drivers, as it simplifies location of all engine faults. Of great advantage as a^i
instructor for the novice, it can be used equally well by the more expert as a work of reference
and review. It can be carried in the tool-box or pocket with ease and will save its cost in
labor eliminated the first time engine trouble manifests itself. Prepared with special refer-
ence to the average man's needs and is a practical review of all motor troubles because it is based
on the actual experience of an automobile engineer-mechanic with the mechanism the chart
describes. It enables the non-technical owner or operator of a Ford car to locate engine
derangements by systematic search, guided by easily recognized symptoms instead of by
guesswork. It makes the average owner independent of the roadside repair shop when tour-
ing. Must be seen to be appreciated. Size 25x38 inches. Printed on heavy bond paper.

Price . . . 25 cents

Chart. Lubrication of the Motor Car Chassis. Compiled by VICTOR W.
PAGE, M.S.A.E.

This chart presents the plan view of a typical six-cylinder chassis of standard design and all
parts are clearly indicated that demand oil, also the frequency with which they must be
lubricated and the kind of oil to use. A practical chart for all interested in motor-car main-
tenance. Size 24x38 inches. Price 25 Cents

Chart. Location of Carbureton Troubles Made Easy. Compiled by VICTOR
W. PAGE, M.S.A.E.

This chart shows all parts of a typical pressure feed fuel supply system and gives causes of
trouble, how to locate defects and means of remedying them. Size 24x38 inches.

Price 25 cents

Chart. Location of Ignition System Troubles Made Easy. Compiled by
VICTOR W. PAGE, M.S.A.E.

In this diagram all parts of a typical double ignition system using battery and magneto current
are shown, and suggestions are given for readily finding ignition troubles and eliminating
them when found. Size 24x38 inches. Price 25 Cents

CATALOGUE OF GOOD, PRACTICAL BOOKS 7

Chart. Location of Cooling and Lubrication System Faults. Compiled by
VICTOR W. PAGE, M.S.A.E.

This composite diagram shows a typical automobile power plant using pump circulated
water-cooling system and the most popular lubrication method. Gives suggestions for cur-
ing all overheating and loss of power faults due to faulty action of the oiling or cooling group.
Size 24x38 inches. Price }5 cents

Chart. Motorcycle Troubles Made Easy. Compiled by VICTOR W. PAGE,
M.S.A.E.

A chart showing sectional view of a single-cylinder gasoline engine. This chart simplifies
location of all power-plant troubles. A single-cylinder motor is shown for simplicity. It
outlines distinctly all parts liable to give trouble and also details the derangements apt to
interfere with smooth engine operation. This chart will prove of value to all who have to do
with the operation, repair or sale of motorcycles. No details omitted. Size 30x20 inches.

35 cents

AVIATION

Aviation Engines, their Design, Construction, Operation and Repair. By

Lieut. VICTOR W. PAGE, Aviation Section, S.C.U.S.R.

A practical work containing valuable instructions for aviation students, mechanicians,
squadron engineering officers and all interested in the construction and upkeep of airplane
power plants.

The rapidly increasing interest in the study of aviation, and especially of the highly developed
internal combustion engines that make mechanical flight possible, has created a demand for a
text-book suitable for schools and home study that will clearly and concisely explain the
workings of the various aircraft engines of foreign and domestic manufacture.
This treatise, written by a recognized authority on all of the practical aspects of internal
combustion engine construction, maintenance and repair fills the need as no other book does.
The matter is logically arranged; all descriptive matter is simply expressed and copiously
illustrated so that anyone can understand airplane engine operation and repair even if with-
out previous mechanical training. This work is invaluable for anyone desiring to become an
aviator or aviation mechanician.

The latest rotary types, such as the Gnome, Monosoupape, and Le Rhone, are fully explained,
as well as the recently developed Vee and radial types. The subjects of carburetion, ignition,
cooling and lubrication also are covered in a thorough manner. The chapters on repair and
maintenance are distinctive and found in no other book on this subject.
Invaluable to the student, mechanic and soldier wishing to enter the aviation service.
Not a technical book, but a practical, easily understood work of reference for all interested
in aeronautical science. 576 octavo pages. 253 specially made engravings. Price, . $3.00 net

GLOSSARY OF AVIATION TERMS

Termes D* Aviation, English-French, French-English. Compiled by Lieuts.
VICTOR W. PAGE, A.S., S.C.U.S.R., and PAUL MONTARIOL of the French
Flying Corps, on duty on Signal Corps Aviation School, Mineola, L. I.

A complete, well illustrated volume intended to facilitate conversation between English-
speaking and French aviators. A very valuable book for all who are about to -leave for duty
overseas.

Approved for publication by Major W. G. Kilner, S.C., U.S.C.O. Signal Corps Aviation
School. Hazlehurst Field, Mineola, L. I.

This book should be in every Aviator's and Mechanic's Kit for ready reference. 128 pages.
Fully illustrated with detailed engravings. Price $1.00

Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.

By Lieut. VICTOR W. PAGE, A.S., S.C.U.S.R.

A large chart outlining all parts of a typical airplane power plant, showing the points where
trouble is apt to occur and suggesting remedies for the common defects. Intended espe-
cially for Aviators and Aviation Mechanics on School and Field Duty. Price . . 50 Cents

BRAZING AND SOLDERING

Brazing and Soldering. By JAMES F. HOBART.

The only book that shows you just bow to handle any job of brazing or soldering that comes
along; it tells you what mixture to use, how to make a furnace if you need one. Full of valu-
able kinks. The fifth edition of this book has just been published, and to it much new mat-
ter and a large number of tested formulae for all kinds of solders and 'fluxes have been added.
Illustrated. Price 25 CCntS

THE NORMAN W. HENLEY PUBLISHING CO.

CHARTS

Aviation Chart. Location of Airplane Power Plant Troubles Made Easy.

By Lieut. VICTOR W. PAGE, A.S., S.C.U.S.R.

A large chart outlining all parts of a typical airplane power plant, showing the points where
trouble is apt to occur and suggesting remedies for the common defects. Intended especially
for Aviators and Aviation Mechanics on School and Field Duty. Price .... 5Q cents

Gasoline Engine Troubles Made EasyA Chart Showing Sectional View of
Gasoline Engine. Compiled by Lieut. VICTOR \V. PAGE, A.S., S.C.U.S.R.

It shows clearly all parts of a typical four-cylinder gasoline engine of the four-cycle type.

It outlines distinctly all parts liable to give trouble and also details the derangements apt

to interfere with smooth engine operation.

Valuable to students, motorists, mechanics, repairmen, garagemen, automobile salesmen,

chauffeurs, motor-boat owners, motor-truck and tractor drivers, aviators, motor-cyclists,

and all others who have to do with gasoline' power plants.

It simplifies location of all engine troubles, and while it will prove invaluable to the novice,

it can be used to advantage by the more expert. It should be on the walls of every public

and private garage, automobile repair shop, club house or school. It can be carried in the

automobile or pocket with ease and will insure against loss of time when engine trouble mani-

fests itself.

This sectional view of engine is a complete review of all motor troubles. It is prepared by a

practical motorist for all who motor. No details omitted. Size 25x38 inches. Price 25 Cents

Lubrication of the Motor Car Chassis.

This chart presents the plan view of a typical six-cylinder chassis of standard design and
all parts are clearly indicated that demand oil, also the frequency with which they must be
lubricated and the kind of oil to use. A practical chart for all interested in motor-car main-
tenance. Size 24x38 inches. Price ................... 25 Cents

Location of Carburetlon Troubles Made Easy.

This chart shows all" parts of a typical pressure feed f

trouble, how to locate defects and means of remedying them. Siz6 24x38 inches.

This chart shows all" parts of a typical pressure feed fuel supply system and gives causes of

Siz

25 cents

Location of Ignition System Troubles Made Easy.

In this chart all parts of a typical double ignition system using battery and magneto current
are shown and suggestions are given for readily finding ignition troubles and eliminating
them when found. Size 24x38 inches. Price ............... 25 Cents

Location of Cooling and Lubrication System Faults.

This composite chart shows a typical automobile power plant using pump circulated water-
cooling system and the most popular lubrication method. Gives suggestions for curing all
overheating and loss of power faults due to faulty action of the oiling or cooling group. Size
24x38 inches. Price ........................... 25 Cents

Motorcycle Troubles Made Easy A Chart Showing Sectional View of Single-
Cylinder Gasoline Engine. Compiled by VICTOR W. PAGE, M.S.A.E.

This chart simplifies location of all power-plant troubles, and will prove invaluable to all
who have to do with the operation, repair or sale of motorcycles. No details omitted. Size
25x38 inches. Price ................. ......... 25 Cents

Location of Ford Engine Troubles Made Easy. Compiled by VICTOR W.
PAGE, M.S.A.E.

This shows clear sectional views depicting all portions of the Ford power plant and auxiliary
groups. It outlines clearly all parts of the engine, fuel supply system, ignition group and
cooling system, that are apt to give trouble, detailing all derangements that are liable to
make an engine lose power, start hard or \vork irregularly. This chart is valuable to students,
owners, and drivers, as it simplifies location of all engine faults. Of great advantage as an
instructor for the novice, it can be used equally well by the more expert as a work of reference
and review. It can be carried in the toolbox or pocket with ease and will save its cost in
labor eliminated the first time engine trouble manifests itself. Prepared with special refer-
ence to the average man's needs and is a practical review of all motor troubles because it is
based on the actual experience of an automobile engineer-mechanic with the mechanism the
chart describes. It enables the non-technical owner or operator of a Ford car to locate en-
gine derangements by systematic search, guided by easily recognized symptoms instead of
by guesswork. It makes the average owner independent of the roadside repair shop when
touring. Must be seen to be appreciated. Size 25x38 inches. Printed on he"avy bond paper.

Price . ................... ............. 25 cents

CATALOGUE OF GOOD, PRACTICAL BOOKS 9

Modern Submarine Chart with Two Hundred Parts Numbered and Named.

A cross-section view, showing clearly and distinctly all the interior of a Submarine of the
latest type. You get more information from this chart, about the construction and opera-
tion of a Submarine, than in any other way. No details omitted everything is accurate
and to scale. It is absolutely correct in every detail, having been approved by Naval En-
gineers. All the machinery **nd devices fitted in a modern Submarine Boat are shown, and
to make the engraving more readily understood all the features are shown in operative form,
with Officers and Men in the act of performing the duties assigned to them in service con-
ditions. This CHART IS REALLY AN ENCYCLOPEDIA OF A SUBMARINE. It
is educational and worth many times its cost. Mailed in a Tube for 25 cents

Box Car Chart.

A chart showing the anatomy of a box car, having every part of the car numbered and ita
proper name given in a reference list. Price 25 CCntS

Gondola Car Chart.

A chart showing the anatomy of a gondola car, having every part of the car numbered and
its proper reference name given in a reference list. Price 25 CCntS

Passenger-Car Chart.

A chart showing the anatomy of a passenger-car, having every part of the car numbered
and its proper name given in a reference list 25 Cents

Steel Hopper Bottom Coal Car.

A chart showing the anatomy of a steel Hopper Bottom Coal Car, having every part of the
car numbered and its proper name given in a reference list. Price . 25 COlltS

Tractive Power Chart.

A chart whereby you can find the tractive power or drawbar pull of any locomotive without
making a figure. Shows what cylinders are equal, how driving wheels and steam pressure
affect the power. What sized engine you need to exert a given drawbar pull or anything you
desire in this line. Price 50 Cents

Horse-Power Chart.

Shows the horse-power of any stationary engine without calculation. No matter what the
cylinder diameter of stroke, the steam pressure of cut-off, the revolutions, or whether con-
densing or non-condensing, it's all there. Easy to use, accurate, and saves time and calcu-
lations. Especially useful to engineers and designers. Price 50 cents

Boiler Room Chart. By GEO. L. FOWLER.

A chart size 14x28 inches showing in isometric perspective the mechanisms belonging in
a modern boiler room. The various parts are shown broken or removed, so that the internal
construction is fully illustrated. Each part is given a reference number, and these, with the
corresponding name, are given in a glossary printed at the sides. This chart is really a dic-
tionary of the boiler room the names of more than 200 parts being given. Price . 25 cents

COKE

Modern Coking Practice, Including Analysis of Materials and Products.

By J. E. CHRISTOPHER and T. H. BYROM.

This, the standard work on the subject, has just been revised. It is a practical work for those
engaged in Coke manufacture and the recovery of By-products. Fully illustrated with fold-
ing olates. It has been the aim of the authors, in preparing this book, to produce one which
shall be of use and benefit to those who are associated with, or interested in, the modern
developments of the industry. Among the Chapters contained in Volume I are: Introduc-
tion; Classification of Fuels; Impurities of Coals; Coal Washing; Sampling and Valuation
of Coals, etc.; Power of Fuels; History of Coke Manufacture; Developments in the Coke
Oven Design; Recent Types of Coke Ovens; Mechanical Appliances at Coke Ovens; Chem-
ical and Physical Examination of Coke. Volume II covers fully the subject of By-Products.
Price, per volume $3.00 net

10 THE NORMAN W. HENLEY PUBLISHING CO.

COMPRESSED AIR

Compressed Air in All Its Applications. By GARDNER D. Hiscox.

This is the most complete book on the subject of Air that has ever been issued, and its thirty-
five chapters include about every phase of the subject one can think of. It may be called
an encyclopedia of compressed air. It is written by an expert, who, irr its 665 pages, has
dealt with the subject in a comprehensive manner, no phase of it being omitted. Includes
the physical properties of air from a vacuum to its highest pressure, its thermodynamics,
compression, transmission and uses as a motive power, in the Operation of Stationary and
Portable Machinery, in Mining, Air Tools, Air Lifts, Pumping of Water, Acids, and Oils;
the Air Blast for Cleaning and Painting the Sand Blast and its Work, and the Numerous
Appliances in which Compressed Air is a Most Convenient and Economical Transmitter of
.Power for Mechanical Work, Railway Propulsion, Refrigeration, and the Various Uses to which
Compressed Air has been applied. Includes forty-four tables of the physical properties of
air, its compression, expansion, and volumes required for various kinds of work, and a list
of patents on compressed air from 1875 to date. Over 500 illustrations, 5th Edition, re-
vised and enlarged.

Cloth bound. Price $5.00

Half Morocco. Price $(J .50

CONCRETE

Concrete Workers' Reference Books. A Series of Popular Handbooks for
Concrete Users. Prepared by A. A. HOUGHTON 50 cents

The author, in preparing this Series, has not only treated on the usual types of construction, but
explains and illustrates molds and systems that are not patented, but which are equal in value
and often superior to those restricted by patents. These molds are very easily and cheaply con-
structed and embody simplicity, rapidity of operation, and the most successful results in the molded
concrete. Each of these books is fully illustrated, and the subjects are exhaustively treated in plain
English.

Concrete Wall Forms. By A. A. HOUGHTON.

A new automatic wall clamp is illustrated with working drawings. Other types of wall forms,
clamps, separators, etc., are also illustrated and explained. .(No. 1 of Series) Price 50 Cents

Concrete Floors and Sidewalks. By A. A. HOUGHTON.

The molds for molding squares, hexagonal and many other styles of mosaic floor and side-
walk blocks are fully illustrated and explained. (No. 2 of Series) Price 50 Cents

Practical Concrete Silo Construction. By A. A. HOUGHTON.

Complete working drawings and specifications are given for several styles of concrete silos,
with illustrations of molds for monolithic and block silos. The tables, data, and information
presented in this book are of the utmost value in planning and constructing all forms of con-
crete silos. (No. 3 of Series) Price 50 Cents

Molding Concrete Chimneys, Slate and Roof Tiles. By A. A. HOUGHTON.

The manufacture of all types of concrete slate and roof tile is fully treated. Valuable data
on all forms of reinforced concrete roofs are contained within its pages. The construction
of concrete chimneys by block and monolithic systems is fully illustrated and described. A
number of ornamental designs of chimney construction with molds are shown in this valuable
treatise. (No. 4 of Series.) Price 50 Cents

Molding and Curing Ornamental Concrete. By A. A. HOUGHTON.

The proper proportions of cement and aggregates for various finishes, also the method of
thoroughly mixing and placing in the molds, are fully treated. An exhaustive treatise on
this subject that every concrete worker will find of daily use and value. (No. 5 of Series.)

Price 50 cents

Concrete Monuments, Mausoleums and Burial Vaults. By A. A. HOUGHTON.

The molding of concrete monuments to imitate the most expensive cut stone is explained
in this treatise, with working drawings of easily built molds. Cutting inscriptions and de-
signs are also fully treated. (No. 6 of Series.) Price 50 Cents

Molding Concrete Bathtubs, Aquariums and Natatoriums. By A. A.

HOUGHTON.

Simple molds and instruction are given for molding many styles of concrete bathtubs, swim-
ming-pools, etc. These molds are easily built and permit rapid and successful work. (No. 7
of Series.) Price 50 Cents

CATALOGUE OF GOOD, PRACTICAL BOOKS 11
Concrete Bridges, Culverts and Sewers. By A. A. HOUGHTON.

A number of ornamental concrete bridges with illustrations of molds are given. A collapsible
center or core for bridges, culverts and sewers is fully illustrated with detailed instructions
for building. (No. 8 of Series.) Price 50 CCntS

Constructing Concrete Porches. By A. A. HOUGHTON.

A number of designs with working drawings of molds are fully explained so any one can eaily
construct different styles of ornamental concrete porches without the purchase of expensive
molds. (No. 9 of Series.) Price 50 cents

Molding Concrete Flower-Pots, Boxes, Jardinieres, Etc. By A. A. HOUGHTON.

The molds for producing many original designs of flower-pots, urns, flower-boxes, jardinieres,
etc., are fully illustrated and explained, so the worker can easily construct and operate same.
(No. 10 of Series.) Price 50 cents

Molding Concrete Fountains and Lawn Ornaments. By A. A. HOUGHTON.

The molding of a number of designs of lawn seats, curbing, hitching posts, pergolas, sun dials
and other forms of ornamental concrete for the ornamentation of lawns and gardens, is fully
illustrated and described. (No. 11 of Series.) Price 50 Cents

Concrete from Sand Molds* By A. A. HOUGHTON.

A Practical Work treating on a process which has heretofore been held as a trade secret by
the few who possessed it, and which will successfully mold every and any class of ornamental
concrete work. The process of molding concrete with sand molds is of the utmost practical
value, possessing the manifold advantages of a low cost of molds, the ease and rapidity of
operation, perfect details to all ornamental designs, density and increased strength of the
concrete, perfect curing of the work without attention and the easy removal of the molds
regardless of any undercutting the design may have. 192 pages. Fully illustrated
Price $2.00

Ornamental Concrete without Molds. By A. A. HOUGHTON.

The process for making ornamental concrete without molds has long been held as a secret,
and now, for the first time, this process is given to the public. The book reveals the secret
and is the only book published which explains a simple, practical method whereby the con-
crete worker is enabled, by employing wood and metal templates of different designs, to mold
or model in concrete any Cornice, Archivolt, Column, Pedestal, Base Cap, Urn or Pier in a
monolithic form right upon the job. These may be molded in units or blocks and then built
up to suit the specifications demanded. This work :s fully illustrated, with detailed engrav-
ings. Price .$3.00

Concrete for the Farm and in the Shop. By H. COLIN CAMPBELL, C.E., E.M.

"Concrete for the Farm and in the Shop" is a new book from cover to cover, illustrating and
describing in plain, simple language many of the numerous applications of concrete within
the range of the home worker. Among -the subjects treated are: Principles of Reinforcing;
Methods of Protecting Concrete so as to Insure Proper Hardening; Home-made Mixers;
Mixing by Hand and Machine; Form Construction, Described and Illustrated by Draw-
ings and Photographs; Construction of Concrete Walls and Fences; Concrete Fence Posts;
Concrete Gate Posts; Corner Posts; Clothes Line Posts; Grape Arbor Posts; Tanks;
Troughs; Cisterns; Hog Wallows; Feeding Floors and Barnyard Pavements; Foundations;
Well Curbs and Platforms; Indoor Floors; Sidewalks; Steps; Concrete Hotbeds and Cold
Frames; Concrete Slab Roofs; Walls for Buildings; Repairing Leaks in Tanks and Cisterns;
and all topics associated with these subjects as bearing upon securing the best results from
concrete are dwelt upon at sufficient length in plain every-day English so that the inexperi-
enced person desiring to undertake a piece of concrete construction can, by following the
directions set forth in this book, secure 100 per cent, success every time. A number of con-
venient and practical tables for estimating quantities, and some practical examples, are also
given. (5x7.) 149 pages. 51 illustrations. Price 75 Cents

Popular Handbook for Cement and Concrete Users. By MYRON H. LEWIS.

This is a concise treatise of the principles and methods employed in the manufacture and use
of cement in all classes of modern works. The author has brought together in this work all
the salient matter of interest to the user of concrete and its many diversified products. The
matter is presented in logical and systematic order, clearly written, fully illustrated and free
from involved mathematics. Everything of value to the concrete user is given, including
kinds of cement employed in construction, concrete architecture, inspection and testing,
waterproofing, coloring and painting, rules, tables, working and cost data. The book com-
prises thirty-three chapters, as follow: Introductory. Kinds of Cement and How They
are Made. Properties. Testing and Requirements of Hydraulic Cement. Concrete and Its
Properties. Sand, Broken Stone and Gravel for Concrete. How to Proportion the Materials.
How to Mix and Place Concrete. Forms of Concrete Construction. The Architectural and
Artistic Possibilities of Concrete. Concrete Residences. Mortars, Plasters and Stucco,
and How to Use Them. The Artistic Treatment of Concrete Surfaces. Concrete Building

12 THE NORMAN W. HENLEY PUBLISHING CO.

Blocks. The Making of Ornamental Concrete. Concrete Pipes, Fences, Posts, etc. Essen-
tial Features and Advantages of Reenforced Concrete. How to Design Reenforced Con-
crete Beams, Slabs and Columns. Explanations of the Methods and Principles in Designing
Reenforced Concrete, Beams and Slabs. Systems of Reenforcement Employed. Reen-
forced Concrete in Factory and General Building Construction. Concrete in Foundation Work.
Concrete Retaining Walls, Abutments and Bulkheads. Concrete Arches and Arch Bridges.
Concrete Beam and Girder Bridges. Concrete in Sewerage and Draining Works. Concrete
Tanks, Dams and Reservoirs. Concrete Sidewalks, Curbs and Pavements. Concrete in
Railroad Construction. The Utility of Concrete on the Farm'. The Waterproofing of Con-
crete Structures. Grout of Liquid Concrete and Its Use. Inspection of Concrete Work.
Cost of Concrete Work. Some of the special features of the book are: 1. The Attention
Paid to the Artistic and Architectural Side of Concrete Work. 2. The Authoritative Treat-
ment of the Problem of Waterproofing Concrete. 3. An Excellent Summary of the Rules
to be Followed in Concrete Construction. 4. The Valuable Cost Data and Useful Tables
given. A valuable Addition to the Library of Every Cement and Concrete User. Price

WHAT IS SAID OF. THIS BOOK:

"The field of Concrete Construction is well covered and the matter contained is well within
the understanding of any person." Engineering-Contracting.

"Should be on the bookshelves of every contractor, engineer, and architect in the land."
National Builder.

Waterproofing Concrete. By MYRON H. LEWIS.

Modern Methods of Waterproofing Concrete and Other Structures. A condensed statement
of the Principles, Rules, and Precautions to be Observed in Waterproofing and Dampproofing
Structures and Structural Materials. Paper binding. Illustrated. Price .... 50 Cents

DICTIONARIES

Aviation Terms, Termes D'Aviation, English-French, French-English.

Compiled by Lieuts. VICTOR W. PAGE, A.S., S.C.U.S.R., and PAUL MON-
TARIOL, of the French Flying Corps, on duty on Signal Corps Aviation School,
Mineola, L. I.

The lists contained are confined to essentials, and special folding plates are included to show
all important airplane parts. The lists are divided in four sections as follows: 1. Flying
Field Terms. 2.-^The Airplane. 3. The Engine. 4. Tools and Shop Terms.
A complete, well illustrated volume intended to facilitate conversation between English-speak-
ing and French aviators. A very valuable book for all who are about to leave for duty over-
seas.

Approved for publication by Major W. G. Kilner, S.C., TJ.S.C.O. Signal Corps Aviation School,
Hazelhurst Field, Mineola, L. I. This book should be in every Aviator's and Mechanic's Kit
for ready reference. 128 pages, fully illustrated, with detailed engravings. Price . . $1.00

Standard Electrical Dictionary. By T. O'CoNOR SLOANE.

DIES METAL WORK

Dies: Their Construction and Use for the Modern Working of Sheet Metals.

By J. V. WOODWORTH.

A most useful book, and one which should be in the hands of all engaged in the press working
of metals; treating on the Designing, Constructing, and Use of Tools, Fixtures and Devices,
together with the manner in which they should be used in the Power Press, for the cheap and
rapid production of the great variety of sheet-metal articles now in use. It is designed
as a guide to the production of sheet-metal parts at the minimum of cost with the
maximum of output. The hardening and tempering of Press tools and the classes of work
which may be produced to the best advantage by the use of dies in the power press are fully
treated. Its 515 illustrations show dies, press fixtures and sheet-metal working devices, the
descriptions of which are so clear and practical that all metal-working mechanics will be able
to understand how to design, construct and use them. Many of the dies and press fixtures
treated were either constructed by the author or under his supervision. Others were built by
skilful mechanics and are in use in large sheet-metal establishments and machine shops.
6th Revised and Enlarged Edition. Price $3.00

CATALOGUE OF GOOD, PRACTICAL BOOKS 13

Punches, Dies and Tools for Manufacturing in Presses. By J. V. WOOD-
WORTH.

This work is a companion volume to the author's elementary work entitled "Dies: Their
Construction and Use." It does not go into the details of die-making to the extent of the
author's previous book, but gives a comprehensive review of the field of operations carried on
by presses. A large part of the information given has been drawn from the author's personal
experience. It might well be termed an Encyclopedia of Die-Making, Punch-Making, Die-
Sinking, Sheet-Metal Working, and Making of Special Tools, Sub-presses, Devices and Mechani-
cal Combinations for Punching, Cutting, Bending, Forming, Piercing, Drawing, Compressing
and Assembling Sheet-Metal Parts, and also Articles* of other Materials in Machine Tools.
2d Edition. Price $4.00

Drop Forging, Die-Sinking and Machine-Forming of Steel. By J. V.

WOODWORTH.

This is a practical treatise on Modern Shop Practice, Processes, Methods, Machine Tools,
and Details treating on the Hot and Cold Machine-Forming of Steel and Iron into Finished
Shapes: together with Tools, Dies, and Machinery involved in the manufacture of Duplicate
Forgings and Interchangeable Hot and Cold Pressed Parts from Bar and Sheet Metal. This
book fills a demand of long standing for information regarding drop-forgings, die-sinking and
machine-forming of steel and the shop practice involved, as it actually exists in the modern
drop-forging shop. The processes of die-sinking and force-making, which are thoroughly
described and illustrated in this admirable work, are rarely to be found explained in such a
clear and concise manner as is here set forth. The process of die-sinking relates to the engrav-
ing or sinking of the female or lower dies, such as are used for drop-forgings, hot and cold
machine-forging, s wedging, and the press working of metals. The process of force-making
relates to the engraving or raising of the male or upper dies used in producing the lower dies
for the press-forming and machine-forging of duplicate parts of metal.

In addition to the arts above mentioned the book contains explicit information regarding the
drop-forging and hardening plants, designs, conditions, equipment, drop hammers, forging
machines, etc., machine forging, hydraulic forging, autogenous welding and shop practice.
The book contains eleven chapters, and the information contained in these chapters is just
what will prove most valuable to the forged-metal worker. All operations described in the
work are thoroughly illustrated by means of perspective half-tones and outline sketches of
the machinery employed. 300 detailed illustrations. Price $2.50

, DRAWING SKETCHING PAPER

Practical Perspective. By RICHARDS and COLVIN.

Shows just how to make all kinds of mechanical drawings in the only practical perspective
isometric. Makes everything plain, so that any mechanic can understand a sketch or drawing
in this way. Saves time in the drawing room, and mistakes in the shops. Contains practical
examples of various classes of work. 4th Edition. Price 50 cents

Linear Perspective Self-Taught. By HERMAN T. C. KRAUS.

This work gives the theory and practice of linear perspective, as used in architectural, engineer-
ing and mechanical drawings. Persons taking up the study of the subject by themselves will
be able, by the use of the instruction given, to readily grasp the subject, and by reasonable
practice become good perspective draftsmen. The arrangement of the book is good; the plate
is on the left-hand, while the descriptive text follows on the opposite page, so as to be readily
referred to. The drawings are on sufficiently large scale to show the work clearly and are
plainly figured. There*is included a self-explanatory chart which gives all information neces-
sary for the thorough understanding of perspective. This chart alone is worth many times
over the price of the book. 2d Revised and Enlarged Edition. Price $2.50

Self-Taught Mechanical Drawing and Elementary Machine Design. By

F. L. SYLVESTER, M.E., Draftsman, with additions by ERIK OBERG, associate
editor of "Machinery."

This is a practical treatise on Mechanical Drawing and Machine Design, comprising the first
principles of geometric and mechanical drawing, workshop mathematics, mechanics, strength
of materials and the calculations and design of machine details. The author's aim has been
to adapt this treatise to the requirements of the practical mechanic and young draftsman
and to present the matter in as clear and concise a manner as possible. To meet the demands
of this class of students, practically all the important elements of machine design have been
dealt with, and in addition algebraic formulas have been explained, and the elements of
trigonometry treated in the manner best suited to the needs of the practical man. The book
isdivided into 20 chapters, and in arranging the material, mechanical drawing, pure and simple,
has been taken up first, as a thorough understanding of the principles of representing objects
facilitates the further study of mechanical subjects. This is followed by the mathematics
necessary for the solution of the problems in machine design which are presented later, and a
practical introduction to theoretical mechanics and the strength of materials. The various
elements entering into machine design, such as cams, gears, sprocket-wheels, cone pulleys,
bolts, screws, couplings, clutches, shafting and fly-wheels, have been treated in such a way
as to make possible the use of the work as a text-book for a continuous course of study. It
is easily comprehended and assimilated even by students of limited previous training. 330
pages, 215 engravings. Price $3.00

16 THE NORMAN W. HENLEY PUBLISHING CO.
How to Become a Successful Electrician. By Prof. T. O'CONOR SLOANE.

Every young man who wishes to become a successful electrician should read this book. It
. tells in simple language the surest and easiest way to become a successful electrician. The
studies to be followed, methods of work, field of operation and the requirements of the suc-
cessful electrician are pointed out and fully explained. Every young engineer will find this an
excellent stepping stone to more advanced works on electricity which he must master before
success can be attained. Many young men become discouraged at the very outstart by at-
tempting to read and study books that are far beyond their comprehension. This book serves
as the connecting link between the rudiments taught in the public schools and the real study
of electricity. It is interesting from cover to cover. 18th Revised Edition, just issued. 205
Illustrated. Price $1.00

Management of Dynamos. By LUMMIS-PATERSON.

A handbook of theory and practice. This work is arranged in three parts. The first part
covers the elementary theory of the dynamo. The second part, the construction and action
of the different classes of dynamos in common use are described; while the third .part relates
to such matters as affect the nractical management and working of dynamos and motors.
4th Edition. 292 pages, 117 illustrations. Price $1.50

Standard Electrical Dictionary. By T. O' CONOR SLOANE.

An indispensable work to all interested in electrical science. Suitable alike for the student
and professional. A practical handbook of reference containing definitions of about 5,000
distinct words, terms and phrases. The definitions are terse and concise and include every
term used in electrical science. . Recently issued. An entirely new edition. Should be in the
possession of all who desire to keep abreast with the progress of this branch of science. In
its arrangement and typography the book is very convenient. The word or term defined is
printed in black-faced type, which readily catches the eye, while the body of the page is in
smaller but distinct type. The definitions are well worded, and so as to be understood by the
non-technical reader. The general plan seems to be to give an exact, concise definition, and
then amplify and explain in a more popular way. Synonyms are also given, and references
to other words and phrases are made. A very complete and accurate index of fifty pages
is at the end of the volume; and as this index contains all synonyms, and as all phrases art
indexed in every reasonable combination of words, reference to the proper place in the body
of the book is readily made. It is difficult to decide how far a book of this character is to
keep the dictionary form, and to what extent it may assume the encyclopedia form. For
some purposes, concise, exactly worded definitions are needed; for other purposes, more
extended descriptions are required. This book seeks to satisfy both demands, and does it
with considerable success. 682 pages, 393 illustrations. 12th Edition.
Price $3.00

Storage Batteries Simplified. By VICTOR W. PAGE, M.E.

A complete treatise on storage battery operating principles, repairs' and applications.
The greatly increasing application of storage batteries in modern engineering and mechanical
work has created a demand for a book that will consider this subject completely and exclu-
sively. This is the most thorougli and authoritative treatise ever published on this subject.
It is written in easily understandable, non-technical language so that any one may grasp
the basic principles of storage battery action as well as their practical industrial applications.
All electric and gasoline automobiles use storage batteries. Every automobile repairman,
dealer or salesman should have a good knowledge of maintenance and repair of these impor-
tant elements of the motor car mechanism. This book not only tells how to charge, care for
and rebuild storage batteries but also outlines all the industrial uses. Learn how they run
street cars, locomotives and factory trucks. Get an understanding of the important functions
they perform in submarine boats, isolated lighting plants, railway switch and signal systems,
marine applications, etc. This book tells how they are used in central station standby service,
for starting automobile motors and in ignition systems. Every practical use of the modern
storage battery is outlined in this treatise. 320 pages, fully illustrated. Price . . . $1.50

Switchboards. By WILUAM BAXTER, JR.

This book appeals to every engineer and electrician who wants to know the practical side
of things. It takes up all sorts and conditions of dynamos, connections and circuits, and
shows by diagram and illustration just how the switchboard should be connected. Includes
direct and alternating current boards, als'o those for arc lighting, incandescent and power
circuits. Special treatment on high voltage boards for power transmission. 2nd Edition.
190 pages, Illustrated. Price $1.50

Telephone Construction, Installation, Wiring, Operation and Maintenance.

By W. H. RADCLIFFE and H. C. GUSHING.

This book is intended for the amateur, the wireman, or the engineer who desires to establish
a means of telephonic communication between the rooms of his home, office, or shop. It
deals only with such things as may be of use to him rather than with theories.
Gives the principles of construction and operation of both the Bell and Independent instru-
ments; approved methods of installing and wiring them; the means of protecting them
from lightning and abnormal currents; their connection together for operation as series or
bridging stations; and rules for their inspection and maintenance. Line wiring and the wiring
and operation of special telephone systems are also treated. Intricate mathematics are
avoided, and all apparatus, circuits and systems are thoroughly described. The appendix

CATALOGUE OF GOOD, PRACTICAL BOOKS 17

contains definitions of units and terms used in the text. Selected wiring tables, which are very
helpful, are also included. Among the subjects treated are Construction, Operation, and
Installation of Telephone Instruments; Inspection and Maintenance of Telephone Instru-
ments; Telephone Line Wiring; Testing Telephone Line Wires and Cables; Wiring and
Operation of Special Telephone Systems, etc. 2nd Edition, Revised and Enlarged. 223
pages, 154 illustrations $1.00

Wireless Telegraphy and Telephony Simply Explained. By ALFRED P.
MORGAN.

This is undoubtedly one of the most complete and comprehensible treatises on the subject
ever published, and a close study of its pages will enable one to master all the details of tht,
wireless transmission of messages. The author has filled a long-felt want and has succeeded
in furnishing a lucid, comprehensible explanation in simple language of the theory and practice
of wireless telegraphy and telephony.

Among the contents are: Introductory; Wireless Transmission and Reception The Aerial
System, Earth Connections The Transmitting Apparatus, Spark Coils and Transformers,
Condensers, Helixes, Spark Gaps, Anchor Gaps, Aerial Switches The Receiving Apparatus,
Detectors, etc. Tuning and Coupling, Tuning Coils, Loose Couplers, Variable Condensers,
Directive Wave Systems Miscellaneous Apparatus, Telephone Receivers, Range of Stations,
Static Interference Wireless Telephones, Sound and Sound Waves, The Vocal Cords and
Ear Wireless Telephone, How Sounds Are Changed into Electric Waves ^Wireless Tele-
phones, The Apparatus Summary. 154 pages, 156 engravings. Price $1.00

Wiring a House. By HERBERT PRATT.

Shows a house already built; tells just how to start about wiring it; where to begin; what
wire to use; how to run it according to Insurance Rules; in fact, just the information you
need. Directions apply equally to a shop. 4th Edition. Price 5 CClllS

FACTORY MANAGEMENT, ETC.

Modern Machine Shop Construction, Equipment and Management. By

O. E. PERRIGO, M.E.

The only work published that describes the modern machine shop or manufacturing plant
from the time the grass is growing on the site intended for it until the finished product is
shipped. By a careful study of its thirty-two chapters the practical man may economically
build, efficiently equip, and successfully manage the modern machine shop or manufacturing
establishment. Just the book needed by those contemplating the erection of modern shop
buildings, the rebuilding and reorganization of old ones, or the introduction of modern shop
methods, time and cost systems. It is a book written and illustrated by a practical shop
man for practical shop men who are too busy to read theories and want facts. It. is the most
complete all-around book of its kind ever published. It is a practical book for practical men,
from the apprentice in the shop to the president in the office. It minutely describes and il-
lustrates the most simple and yet the most efficient time and cost system yet devised. 2nd
Revised and Enlarged Edition, just issued. 384 pages, 219 illustrations. Price . . . $5.00

FUEL

Combustion of Coal and the Prevention of Smoke. By WM. M. BARR.

This book has been prepared with special reference to the generation of heat by the com-
bustion of the common fuels found in the United States, and deals particularly with the con-
ditions necessary to the economic and smokeless combustion of bituminous coals in Stationary
and Locomotive Steam Boilers.

The presentation of this 'important subject is systematic and progressive. The arrangement
of the book is in a series of practical questions to which are appended accurate answers, which
describe in language, free from technicalities, the several processes involved in the furnace
combustion of American fuels; it clearly states the essential requisites for perfect combustion,
and points out the best methods for furnace construction for obtaining the greatest quantity
of heat from any given quality of coal. Nearly 350 pages, fully illustrated. Price . . $1.00

Smoke Prevention and Fuel Economy. By BOOTH and KERSHAW.

A complete treatise for all interested in smoke prevention and combustion, being based on
the German work of Ernst Schmatolla, but it is more than a mere translation of the German
treatise, much being added. The authors show as briefly as possible the principles of fuel
combustion, the methods which have been and are at present in use, as well as the proper
scientific methods for obtaining all the energy in the coal and burning it without smoke.
Considerable space is also given to the examination of the waste gases, and several of the
representative English and American mechanical stoker and similar appliances are described.
The losses carried away in the waste gases are thoroughly analyzed and discussed in the Ap-
pendix, and abstracts are also here given of various patents on combustion apparatus. The
book is complete and contains much of value to all who have charge of large plants. 194 pages.
Illustrated. Price $.5()

18 THE NORMAN W. HENLEY PUBLISHING CO.

GAS ENGINES AND GAS

Gas, Gasoline and Oil Engines. By GARDNER D. Hiscox. Revised by
VICTOR W. PAGE, M.E.

Just issued New 1918 Edition, Revised and Enlarged. Every user of a gas engine needs
this book. Simple, instructive and right up-to-date. The only complete work on the subject.
Tells all about internal combustion engineering, treating exhaustively on the. design, con-
struction and practical application of all forms of gas, gasoline, kerosene and crude petroleum-
oil engines. Describes minutely all auxiliary systems, such as lubrication, carburetion and
ignition. Considers the theory and management of all forms of explosive motors for sta-
tionary and marine work, automobiles, aeroplanes and motor-cycles. Includes also Producer
Gas and Its Production. Invaluable instructions for all students, gas-engine owners, gas-
engineers, patent experts, designers, mechanics, draftsmen arid all having to do with the
modern power. Illustrated by over 400 engravings, many specially made from engineering
drawings, all in correct proportion. 650 pages, 435 engravings. Price .... $2.50 net

The Gasoline Engine on the Farm: Its Operation, Repair and Uses. By

XENO W. PUTNAM.

This is a practical treatise on the Gasoline and Kerosene Engine intended for the man who
wants to know just how to manage his engine and how to apply it to all kinds of farm work
to the best advantage.

This book abounds with hints and helps for the farm and suggestions for the home and house-
wife. There is so much of value in this book that it is impossible to adequately describe it
in such small space. Suffice to say that it is the kind of a book every farmer will appreciate
and every farm home ought to have. Includes selecting the most suitable engine for farm
work, its most convenient and efficient installation, with chapters on troubles, their remedies,
and how to avoid them. The care and management of the farm tractor in plowing, harrowing,
harvesting and road grading are fully covered; also plain directions are given for handling
the tractor on the road. Special attention is given to relieving farm life of its drudgery by
applying power to the disagreeable small tasks which must otherwise be done by hand. Many
home-made contrivances for cutting wood, supplying kitchen, garden, and barn with water,
loading, hauling and unloading hay, delivering grain to the bins or the feed trough are in-
cluded; also full directions for making the engine milk the cows, churn, wash, sweep the
house and clean the windows, etc. Very fully illustrated with drawings of working parts and
cuts snowing Stationary, Portable and Tractor Engines doing all kinds of farm work. All
money-making farms utilize power. Learn how to utilize power by reading the pages of this
book. It is an aid to the result getter, invaluable to the up-to-date farmer, student, black-
smith, implement dealer and, in fact, all who can apply practical knowledge of stationary
gasoline engines or gas tractors to advantage. 530 pages. Nearly 180 engravings. Price $2.00

WHAT IS SAID OF THIS BOOK:

"Am much pleased with the book and find it to be very complete and up-to-date. I will
heartily recommend it to students and farmers whom I think would stand in need of such a
work, as I think it is an exceptionally good one." N. S. Gardiner, Prof, in Charge, Clemson
Agr. College of S. C.; Dept. of Agri. and Agri. Exp. Station, Clemson College, S. C.
"I feel that Mr. Putnam's book covers the main points which a farmer should know." R. T.
Burdick, Instructor in Agronomy, University of Vermont, Burlington, Vt.

Gasoline Engines: Their Operation, Use and Care. By A. HYATT VERRILL.

The simplest, latest and most comprehensive popular work published on Gasoline Engines,
describing what the Gasoline Engine is; its construction and operation; how to install it;
how to select it; how to use it and how to remedy troubles encountered. Intended for Owners,
Operators and Users of Gasoline Motors of all kinds. This work fully describes and illustrates the
various types of Gasoline Engines used in Motor Boats, Motor Vehicles and Stationary Work.
The parts, accessories and appliances are described with chapters on ignition, fuel, lubrication,
operation and engine troubles. Special attention is given to the care, operation and repair
of motors, with useful hints and suggestions on emergency repairs and makeshifts. A com-
plete glossary of technical terms and an alphabetically arranged table of troubles and their
symptoms form most valuable and unique features of this manual. Nearly every illustration
in the book is original, having been made by the author. Every page is full of interest and
value. A book which you cannot afford to be without. 275 pages, 152 specially made
engravings. Price . . $1.50

Gas Engine Construction, or How to Build a Half-horsepower Gas Engine.

By PARSELL and WEED.

A practical treatise of 300 pages describing the theory and principles of the action of Gas
Engines of various types and the design and construction of a half-horsepower Gas Engine,
with illustrations of the work in actual progress, together with the dimensioned working draw-
ings, giving clearly the sizes of the various details; for the student, the scientific investigator,
and the amateur mechanic. This book treats of the subject more from the standpoint of
practice than that of theory. The principles of operation of Gas Engines are clearly and
simply described, and then the actual construction of a half-horsepower engine is taken up,
step by step, showing in detail the making of the Gas Engine. 3rd Edition. 300 pages.

CATALOGUE OF GOOD, PRACTICAL BOOKS 19

How to Run and Install Two- and Four-Cycle Marine Gasoline Engines.

By C. VON CULIN.

Revised and enlarged edition just issued. The object of this little book is to furnish a pocket
instructor for the beginner, the busy man who uses an engine for pleasure or profit, but who
does not have the time or inclination for a technical book, but simply to thoroughly under-
stand how to properly operate, install and care for his own engine. The index refers to each
trouble, remedy, and subject alphabetically. Being a quick reference to find the cause, remedy
and prevention for troubles, and to become an expert with his own engine. Pocket size.
Paper binding. Price 25 CCIltS

Modern Gas Engines and Producer Gas Plants. By R. E. MATHOT.

A guide for the gas engine designer, user, and engineer in the construction, selection, purchase,
installation, operation, and maintenance of gas engines. More than one book on gas engines
has been written, but not one has thus far even encroached on the field covered by this book.
Above all, Mr. Mathot's work is a practical guide. Recognizing the need of a volume that
would assist the gas engine user in understanding thoroughly the motor upon which he depends
for power, the author has discussed his subject without the help of any mathematics and with-
out elaborate theoretical explanations. Every part of the gas engine is described in detail,
tersely, clearly, with a thorough understanding of the requirements of the mechanic. Help-
ful suggestions as to the purchase of an engine, its installation, care, and operation, form a
most valuable feature of the work. 320 pages, 175 detailed illustrations. Price . . . $2. 50

The Modern Gas Tractor. By VICTOR W. PAGE, M.E.

A complete treatise describing all types and sizes of gasoline, kerosene and oil tractors. Con-
siders design and construction exhaustively, gives complete instructions for care, operation and
repair, outlines all practical applications on the road and in the field. The best and latest
work on farm tractors and tractor power plants. A work needed by farmers, students, black-
smiths, mechanics, salesmen, implement dealers, designers and engineers. 2nd Edition, Re-
vised. 504 pages, 228 illustrations, 3 folding plates. Price $2.00

GEARING AND CAMS

Bevel Gear Tables. By D. AG. ENGSTROM.

A book that will at once commend itself to mechanics and draftsmen. Does away with all
the trigonometry and fancy figuring on bevel gears, and makes it easy for anyone to lay them
out or make them just right. There are 36 full-page tables that show every necessary dimen-
sion for all sizes or combinations you're apt to need. No puzzling, figuring or guessing. Gives
placing distance, all the angles (including cutting angles), and the correct cutter to use. A
copy of this prepares you for anything in the bevel-gear line. 3rd Edition. 66 pages.
Price $1.00

Change Gear Devices. By OSCAR E. PERRIGO.

A practical book for every designer, draftsman, and mechanic interested in the invention and
development of the devices for feed changes on the different machines requiring such mechanism.
All the necessary information on this subject is taken up, analyzed, classified, sifted, and con-
centrated for the use of busy men who have not the time to go through the masses of irrelevant
matter with which such a subject is usually encumbered and select such information as will
be useful to them.

It shows just what has been done, how it has been done, when it was done, and who did it.
It saves time in hunting up patent records and re-inventing old ideas. 88 pages. 3rd Edition,
^ice $1.00

Drafting of Cams. By Louis ROTTILLION.

The laying out of cams is a serious problem unless you know how to go at it right. This puts
you on the right road for practically any kind of cam you are likely to run up against. 3rd
Edition. Price 35 (Tilts

HYDRAULICS

Hydraulic Engineering. By GARDNER D. Hiscox.

A treatise on the properties, power, and resources of water for all purposes. Including the
measurement of streams, the flow of water in pipes or conduits; the horsepower of falling water,
turbine and impact water-wheels, wave motors, centrifugal, reciprocating and air-lift pumps.
With 300 figures and diagrams and 36 practical tables. All who are interested in water-works
development will find this book a useful one, because it is an entirely practical treatise upon
a subject of present importance and cannot fail in having a far-reaching influence, and for this
reason should have a place in the working library of every engineer. Among the subjects
treated are: Historical Hydraulics; Properties of Water; Measurement of the Flow of Streams;

23 THE NORMAN W. HENLEY PUBLISHING CO.

Flow from Sub-surface Orifices and Nozzles; Flow of Water in Pipes; Siphons of Various
Kinds; Dams and Great Storage Reservoirs; City and Town Water Supply; Wells and Their
Reinforcement; -Air-lift Methods of Raising Water; Artesian Wells; Irrigation of Arid Dis-
tricts; Water Power; Water Wheels; Pumps and Pumping Machinery; Reciprocating Pumps;
Hydraulic Power Transmission; Hydraulic Mining; Canals; Ditches; Conduits and Pipe
Lines; Marine Hydraulics; Tidal and Sea Wave Power, etc. 320 pages. Price . . . $4.00

ICE AND REFRIGERATION

Pocketbook of Refrigeration and Ice Making. By A. J. WALLIS-TAYLOR.

This is one of the latest and most comprehensive reference books published on the subject of
refrigeration and cold storage. It explains the properties and refrigerating effect of the dif-
ferent fluids in use, the management of refrigerating machinery and the construction and insu-
lation of cold rooms with their required pipe surface for different degrees of cold; freezing
mixtures and non-freezing brines, temperatures of cold rooms for all kinds of provisions, cold
storage charges for all classes of goods, ice making and storage of ice, data and memoranda
for constant reference by refrigerating engineers, with nearly one hundred tables containing
valuable references to every fact and condition required in the installment and operation of a
refrigerating plant. New edition just published. Price $1.50

INVENTIONS PATENTS

Inventors' Manual: How to Make a Patent Pay.

This is a book designed as a guide to inventors in perfecting their inventions, taking out their
patents and disposing of them. It is not in any sense a Patent Solicitor's Circular nor a Patent
Broker's Advertisement. No advertisements of any description appear in the work. It is a
book containing a quarter of a century's experience of a successful inventor, together with
notes based upon the experience of many other inventors.

Among the subjects treated in this work are: How to Invent. How to Secure a Good Patent.
Value of Good Invention. How to Exhibit an Invention. How to Interest Capital. How
to Estimate the Value of a Patent. Value of Design Patents. Value of Foreign Patents.
Value of Small inventions. Advice on Selling Patents. Advice on the Formation of Stock
Companies. Advice on the Formation of Limited Liability Companies. Advice on Disposing
of Old Patents. Advice as to Patent Attorneys. Advice as to Selling Agents. Forms of
Assignments. License and Contracts. State Laws Concerning Patent Rights. 1900 Census
of the United States by Counts of Over 10,000 Population. Revised Edition. 120 pages.
Price $1.00

KNOTS

Knots, Splices and Rope Work. By A. HYATT VERRILL.

This is a practical book giving complete and simple directions for making all the most useful
and ornamental knots in common use, with chapters on Splicing, Pointing, Seizing, Serving,
etc. This book is fully illustrated with 154 original engravings, which show how each knot,
tie or splice is formed, and its appearance when finished. The book will be found of the greatest
value to Campers, Yachtsmen, Travelers, Boy Scouts, in fact, to anyone having occasion to
use or handle rope or knots for any purpose. The book is thoroughly reliable and practical,
and is not only a guide, but a teacher. It is the standard work on the subject. Among the
contents are: 1. Cordage, Kinds of Rope. Construction of Rope, Parts of Rope Cable and
Bolt Rope. Strength of Rope, Weight of Rope. 2. Simple Knots and Bends. Terms Used
in Handling Rope. Seizing Rope. 3. Ties and Hitches. 4. Noose, Loops and Mooring
Knots. 5. Shortenings, Grommets and Salvages. 6. Lashings, Seizings and Splices. 7.
Fancy Knots and Rope Work. 128 pages, 150 original engravings. 2nd Revised Edition.

Price . 75 cents

LATHE WORK

Lathe Design, Construction, and Operation, with Practical Examples of
Lathe Work. By OSCAR E. PERRIGO.

A new, revised edition, and the only complete American work on the subject, written by a
man who knows not only how work ought to be done, but who also knows how to do it, and
how to convey this knowledge to others. It is strictly up-to-date in its descriptions and
illustrations. Lathe history and the relations of the lathe to manufacturing are given;
also a description of the various devices for feeds and thread-cutting mechanisms from early
efforts in this direction to the present time. Lathe design is thoroughly discussed, includ-
ing back gearing, driving cones, thread-cutting gears, and all the essential elements of the
modern lathe. The classification of lathes is taken up, giving the essential differences of
the several types of lathes including, as is usually understood, engine lathes, bench lathes,
speed lathes, forge lathes, gap lathes, pulley lathes, forming lathes, multiple-spindle lathes,
rapid-reduction lathes, precision lathes, turret lathes, special lathes, electrically driven lathes,

CATALOGUE OF GOOD, PRACTICAL BOOKS 21

etc. In addition to the complete exposition on construction and design, much practical
matter on lathe installation, care and operation has been incorporated in the enlarged new-
edition. All kinds of lathe attachments for drilling, milling, etc., are described and com-
plete instructions are given to enable the novice machinist to grasp the art of lathe operation
as well as the principles involved in design. A number of difficult machining operations
are described at length and illustrated. The new edition has nearly 500 pages and 350 illus-
trations. Price $2.50

WHAT IS SAID OF THIS BOOK:

"This is a lathe book from beginning to end, and is just the kind of a bo9k which one de-
lights to consult a masterly treatment of the subject in hand." Engineering News.
"This work will be of exceptional interest to any one who is interested in lathe practice, as
one very seldom sees such a complete treatise on a subject as this is on the lathe." Cana-
dian Machinery.

Practical Metal Turning. By JOSEPH G. HORNEB.

A work of 404 pages, fully illustrated, covering in a comprehensive manner the modern prac-
tice of machining metal parts in the lathe, including the regular engine lathe, its essential
design, its uses, its tools, its attachments, and the manner of holding the work and perform-
ing the operations. The modernized engine lathe, its methods, tools and great range of accu-
rate work. The turret lathe, its tools, accessories and methods of performing its functions.
Chapters on special work, grinding, tool holders, speeds, feeds, modern tool steels, etc.
Second edition ' $3.50

Turning and Boring Tapers. By FRED H. COLVIN.

There are two ways to turn tapers; the right way and one other. This treatise has to do
with the right way; it tells you how to start the work properly, how to set the lathe, what
tools to use and how to use them, and forty and one other little things that you should know.
Fourth edition 25 CClltS

LIQUID AIR

Liquid Air and the Liquefaction of Gases. By T. O'CONOR SLOANE.

This book gives the history of the theory, discovery and manufacture of Liquid Air, arid.

contains an illustrated description of all the experiments that have excited the wonder of

audiences all over the country. It shows how liquid air, like water, is carried hundreds of

miles and is handled in open buckets. It tells what may be expected from it in the near

future.

A book that renders simple one of the most perplexing chemical problems of the century.

Startling developments illustrated by actual experiments.

It is not only a work of scientific interest and authority, but is intended for the general reader,

being written in a popular style easily understood by every one. Second edition. 365-

pages. Price $2.00

LOCOMOTIVE ENGINEERING

Air-Brake Catechism. By ROBERT H. BLACKALL.

This book is a standard text-book. It covers the Westinghouse Air-Brake Equipment,
including the No. 5 and the No. 6 E.-T. Locomotive Brake Equipment; the K (Quick Ser-
vice) Triple Valve for Freight Service; and the Cross-Compound Pump. The operation of
all parts of the apparatus is explained in detail, and a practical way of finding their pecu-
liarities and defects, with a proper remedy, is given. It contains 2,000 questions with their
answers, which will enable any railroad man to pass any examination on the .subject of
Air Brakes. Endorsed and used by air-brake instructors and examiners 9n. nearly every
railroad in the United States. Twenty-sixth edition. 411 pages, fully illustrated with
colored plates and diagrams. Price $2.00

American Compound Locomotives. By FRED H. COLVIN.

The only book on compounds for the engineman or shopman that shows in a plain, prac-
tical way the various features of compound locomotives in use. Shows how they are made,
what to do when they break down or balk. Contains sections as follows: A Bit of History.
Theory of Compounding Steam Cylinders. Baldwin Two-Cylinder Compound. Pittsburgh
Two-Cylinder Compound. Rhose Island Compound. Richmond Compound. Rogers Com-
pound. Schenectady Two-Cylinder Compound. Vauclain Compound. Tandem Compounds.
Baldwin Tandem. The Colvin-Wightman Tandem. Scbenectady Tandem. Balanced
Locomotives. Baldwin Balanced Compound. Plans for Balancing. Locating Blows.
Breakdowns. Reducing Valves. Drifting. Valve Motion. Disconnecting. Power of Com-
pound Locomotives. Practical Notes.

Fully illustrated and containing ten special "Duotone" inserts on heavy Plate Paper, show-
ing different types of Compounds. 142 pages. Price ..... . $1.00

22 THE NORMAN W. HENLEY PUBLISHING CO.

Application of Highly Superheated Steam to Locomotives. By ROBERT
GARBE.

A practical book which cannot be recommended too highly to those motive-power men who
are anxious to maintain the highest efficiency in their locomotives. Contains special chap-
ters on Generation of Highly Superheated Steam; Superheated Steam and the Two-Cylinder
Simple Engine; Compounding and Superheating; Designs of Locomotive Superheaters;
Constructive Details of Locomotives Using Highly Superheated Steam. Experimental and
Working Results. Illustrated with folding plates and tables. Cloth. Price .... $3.50

Combustion of Coal and the Prevention of Smoke. By WM. M. BARR.

This book has been prepared with special reference to the generation of heat by the com-
bustion of the common fuels found in the United States and deals particularly with the
conditions- necessary to the economic and smokeless combustion of bituminous coal in Sta-
tionary and Locomotive Steam Boilers.

Presentation of this important subject is systematic and progressive. The arrangement of
the book is in a series of practical questions to which are appended accurate answers, which
describe in language free from technicalities the several processes involved in the furnace
combustion of American fuels; it clearly states the essential requisites for perfect combus-
tion, and points out the best methods of furnace construction for obtaining the greatest
quantity of heat from any given quality of coal. Nearly 350 pages, fully illustrated.
Price $1.00

Diary of a Round-House Foreman. By T. S. REILLY.

This is the greatest book of railroad experiences ever published. Containing a fund of in-
formation and suggestions along the line of handling men, organizing, etc., that one cannot
afford to miss. 176 pages. Price 1 .00

Link Motions, Valves and Valve Setting. By FRED H. COLVIN, Associate Editor
of "American Machinist."

A handy book for the engineer or machinist that clears up the mysteries of valve setting.
Shows the different valve gears in use, how they work, and why. Piston and slide valves
of different types are illustrated and explained. A book that every railroad man in the
motive-power department ought to have. Contains chapters on Locomotive Link Motion,
Valve Movements, Setting Slide Valves, Analysis by Diagrams, Modern Practice, Slip of
Block Slice Valves, Piston Valves, Setting Piston Valves, Joy-Allen Valve Gear, Walschaert
Valve Gear, Gooch Valve Gear, Alfree-Hubbell Valve Gear, etc., etc. Fully illustrated.

Price 50 cents

Locomotive Boiler Construction. By FRANK A. KLEINHANS.

The construction of boilers in general is treated and, following this, the locomotive boiler
is taken up in the order in which its various parts go through the shop. Shows all types
of boilers used; gives details of construction; practical facts, such as life of riveting, punches
and dies; work done per day, allowance for bending and flanging sheets and other data.
Including the recent Locomotive Boiler .Inspection Laws and Examination Questions with
their answers for Government Inspectors. Contains chapters on Laying-Out Work; Flang-
ing and Forging; Punching; Shearing; Plate Planing; General Tables; Finishing Parts;
Bending; Machinery Parts; Riveting; Boiler Details; Smoke-Box Details; Assembling
and Calking; Boiler-Shop Machinery, etc., etc.

There isn't a man who has anything to do with boiler work, either new or repair work, who
doesn't need this book. The manufacturer, superintendent, foreman and boiler worker
all need it. No matter what the type of bioler, you'll find a mint of information that you
wouldn't be without. Over 400 pages, five large folding plates. Price $3.00

Locomotive Breakdowns and their Remedies. By GEO. L. FOWLER. Re-
vised by WM. W. WOOD, Air-Brake Instructor. Just issued. Revised pocket
edition.

It is out of the question to try and tell you about every subject that is covered in this pocket
edition of Locomotive Breakdowns. Just imagine all the common troubles that an engineer
may expect to happen some time, and then add all of the unexpected ones, troubles that could
occur, but that you have never thought about, and you will find that they are all treated with
the very best methods of repair. Walschaert Locomotive Valve Gear Troubles, Electric
Headlight Troubles, as well as Questions and Answers on the Air Brake are all included. 312
pages. 8th Revised Edition. Fully illustrated. Price $1.00

Locomotive Catechism. By ROBERT GRIMSHAW.

The revised edition of "Locomotive Catechism," by Robert Grimshaw, is a New Book from
Cover to C9yer. It contains twice as many pages and double the number of illustrations of
previous editions. Includes the greatest amount of practical information ever published on
the construction and management of modern locomotives. Specially Prepared Chapters on
the Walschaert Locomotive Valve Gear, the Air-Brake Equipment and the Electric Headlight
are given.

CATALOGUE OF GOOD, PRACTICAL BOOKS 23

It commends itself at once to every Engineer and Fireman, and to all who are going in for
examination or promotion. In plain language, with full, complete answers, not only all the
questions asked by the examining engineer are given, but those which the young and less
experienced would ask the veteran, and which old hands ask as "stickers." It is a veritable
Encyclopedia of the Locomotive, is entirely free from mathematics, easily understood and
thoroughly up to date. Contains over 4,000 Examination Questions with their Answe
825 pages, 437 illustrations, and 3 folding plates. 28th Revised Edition. Price

Practical Instructor and Reference Book for Locomotive Firemen and
Engineers. By CHAS. F. LOCKHART.

An entirely new book on the Locomotive. It appeals to every railroad man, as it tells him
how tilings are done and the right way to do them. Written by a man who has had years of
practical experience in locomotive shops and on the road firing and running. The information
given in this book cannot be found in any other similar treatise. Eight hundred and fifty-one
questions with their answers are included, which will prove specially helpful to those preparing
for examination. Practical information on: The Construction and Operation of Locomotives,
Breakdowns and their Remedies, Air Brakes and Valve Gears. Rules and Signals are handled
in a thorough manner. As a book of reference it cannot be excelled. The book is divided
in to six parts, as follows: 1. The Fireman's Duties. 2. General Description of the Locomotive.
3. Breakdowns and their Remedies. 4. Air Brakes. 5. Extracts from Standard Rules.
6. Questions for Examination. The 851 questions have been carefully selected and arranged.
These cover the examinations required by the different railroads. 368 pages, 83 illustrations.
Price $1.50

Prevention of Railroad Accidents^ or Safety in Railroading. By GEORGE
BRADSHAW.

This book is a heart-to-heart talk with Railroad Employees, dealing with facts, not theories,
and showing the men in the ranks, from every-day experience, how accidents occur and how
they may be avoided. The book is illustrated with seventy original photographs and drawings
showing the safe and unsafe methods of work. No visionary schemes, no ideal pictures.
Just Plain Facts and Practical Suggestions are given. Every railroad employee who reads the
book is a better and safer man to have in railroad service. It gives just the information which
will be the means of preventing many injuries and deaths. All railroad employees should
procure a copy, read it, and do their part in preventing accidents. 169 pages. Pocket size.
Fully illustrated. Price 50 cents

Train Rule Examinations Made Easy. By G. E. COLLINQWOOD.

This is the only practical work on train rules in print. Every detail is covered, and puzzling
points are explained in simple, comprehensive language, making it a practical treatise for the
Train Dispatcher, Engineman, Trainman, and all others who have to do with the movements
of trains. Contains complete and reliable information of the Standard Code of Train Rules
for single track. Shows Signals in Colors, as used on the different roads. Explains fully the
practical application of train orders, giving a clear and definite understanding of all orders
which may be used. The meaning and necessity for certain rules are explained in such a
manner that the student may know beyond a doubt the rights conferred under any orders he
may receive or the action required by certain rules. As nearly all roads require trainmen to
pass regular examinations, a complete set of examination questions, with their answers, are
included. These will enable the student to pass the required examinations with credit to
himself and the road for which he works. 2nd Edition, Revised. 256 pages, fully illustrated,
with Train Signals in Colors. Price $1.25

The Walschaert and Other Modern Radial Valve Gears for Locomotives.

By WM. W. WOOD.

If you would thoroughly understand the Walschaert Valve Gear you should possess a copy
of this book, as the author takes the plainest form 9f a steam engine a stationary engine in
the rough, that will only turn its crank in one direction and from it builds up, with the read-
er's help, a modern locomotive equipped with the Walschaert Valve Gear, complete. The
points discussed are clearly illustrated: Two large folding plates that show the positions of
the valves of both inside or outside admission type, as well as the links and other parts of the
gear when the crank is at nine different points in its revolution, are especially valuable in mak-
ing the movement clear. These employ sliding cardboard models which are contained in a
pocket in the cover.

The book is divided into five general divisions, as follows: 1. Analysis of the gear. 2. De-
signing and erecting the gear. 3. Advantages of the gear. 4. Questions and answers relating
to the Walschaert Valve Gear. 5. Setting valves with the Walschaert Valve Gear; the three
primary types of locomotive valve motion; modern radial valve gears other than the Wal-
schaert ; the Hobart All-free Valve and Valve Gear, with questions and answers on breakdowns:
the Baker-Pilliod Valve Gear; the Improved Baker-Pilliod Valve Gear, with questions and
answers on breakdowns.

The questions with full answers given will be especially valuable to firemen and engineers in
preparing for an examination for promotion. 245 pages. 3rd Revised Edition. Price $1.50

24 THE NORMAN W. HENLEY PUBLISHING CO.

Westinghouse E-T Air-Brake Instruction Pocket Book. By WM. W. WOOD,
Air-Brake Instructor.

Here is a book for the railroad man, and the man who aims to be one. It is without doubt
the only complete work published on the Westinghouse E-T Locomotive Brake Equipment.
Written by an Air-Brake Instructor who knows just what is needed. It covers the subject
thoroughly. Everything about the New Westinghouse Engine and Tender Brake Equip-
ment, including the standard No. 5 and the Perfected No. 6 style of brake, is treated in detail.
Written in plain English and profusely illustrated with Colored Plates, which enable one to
trace the flow of pressures throughout the entire equipment. The best book ever published
on the Air Brake. Equally good for the beginner and the advanced engineer. Will pass any
one through any examination. It informs and enlightens you on every point. Indispensable
to every enginernan and trainman.

Contains examination questions and answers on the E-T equipment. Covering what the E-T
Brake is. How it should be operated. What to do when defective. Not a question can be
asked of the engineman up for promotion, on either the No. 5 or the No. 6 E-T equipment,
that is not asked and answered in the book. If you want to thoroughly understand the E-T
equipment get a copy of this book. It covers every detail. Makes- Air-Brake troubles and
examinations easy. Price $1.50

MACHINE-SHOP PRACTICE

American Tool Making and Interchangeable Manufacturing. By J. V.

WOODWORTH.

A "shoppy" book, containing no theorizing, n'o problematical or experimental devices. There
are no badly proportioned and impossible diagrams, no catalogue cuts, but a valuable collec-
tion of drawings and descriptions of devices, the rich fruits of the author's own experience.
In its 500-odd pages the one subject only, Tool Making, and whatever relates thereto, is dealt
with. The work stands without a rival. It is a complete, practical treatise, on the art of
American Tool Making and system of interchangeable manufacturing as carried on to-day in
the United States. In it are described and illustrated all of the different types and classes of
small tools, fixtures, devices, and special appliances which are in general use in all machine-
manufacturing and metal-working establishments where economy, capacity, and interchange-
ability in the production of machined metal parts are imperative. The science of jig making
is exhaustively discussed, and particular attention is paid to drill jigs, boring, profiling arid
milling fixtures and other devices in which the parts to be machined are located and fastened
within the contrivances. All of the tools, fixtures, and devices illustrated and described have
been or are used for the actual production of work, such as parts of drill presses, lathes, patented
machinery, typewriters, electrical apparatus, mechanical appliances, "brass goods, composition
parts, mould products, sheet-metal articles, drop-forgings, jewelry, watches, medals, coins, etc.
531 pages. Price $4.00

HENLEY'S ENCYCLOPEDIA OF PRACTICAL ENGINEERING AND ALLIED
TRADES. EDITED by JOSEPH G. HORNER, A.M.I., M.E.

This set of five volumes contains about 2,500 pages with thousands of illustrations, including
diagrammatic and sectional drawings with full explanatory details. This W9rk covers the
entire practice of Civil and Mechanical Engineering. The best known experts in all branches
of engineering have contributed to these volumes. The Cyclopedia is admirably well adapted
to the needs of the beginner and the self-taught practical man, as well as the mechanical
engineer, designer, draftsman, shop superintendent, foreman, and machinist. The work will
be found a means of advancement to any progressive man. It is encyclopedic in scope, thor-
ough and practical in its treatment on technical subjects, simple and clear in its descriptive
matter, and without unnecessary technicalities or formulae. The articles are as brief as may
be and yet give a reasonably clear and explicit statement of the subject, and are written by
men who have had ample practical experience in the matters of which they write. It tells
you all you want to know about engineering and tells it so simply, so clearly, so concisely, that
one cannot help but understand. As a work of reference it is without a peer. Complete
set of five volumes, price . $25 .00

The Modern Machinist. By JOHN T. USHER.

This is a book, showing by plain description and by profuse engravings made expressly for
the work, all that is best, most advanced, and of the highest efficiency in modern machine-
shop practice, tools and implements, showing the way by which and through which, as Mr.
Maxim says, "American machinists have. become and are the finest mechanics in the world.
Indicating as it does, in every line, the familiarity of the author with every detail of daily
experience in the shop, it cannot fail to be of service to any man practically connected with
the shaping or finishing of metals.

There is nothing experimental or visionary about the book, all ^devices being in actual use
and giving good results. It might be called a compendium of shop methods, showing a
variety of special tools and appliances which will give new ideas to many mechanics, from
the superintendent down to the man at the bench. It will be found a valuable addition to
any machinist's library, and should be consulted whenever a new or difficult job is to be
done, whether it is boring, milling, turning, or planing, as they are all treated in a practical
manner. Fifth edition. 320 pages. 250 illustrations. Price 2.50

CATALOGUE OF GOOD, PRACTICAL BOOKS 25

THE WHOLE FIELD OF MECHANICAL MOVEMENTS
COVERED BY MR. HISCOX'S TWO BOOKS

We publish two books by Gardner D. Hiscox that will keep you from "inventing' 1 things that have
been done before, and suggest ways of doing things that you have not thought of before. Many a
man spends time and money pondering over some mechanical problem, only to learn, after he
has solved the problem, that the same thing has been accomplished and put in practice by others
long before. Time and money spent in an effort to accomplish what has already been accomplished
are time and money LOST. The whole field of mechanics, every known mechanical movement,
and practically every device are covered by these two books. If the thing you want has been invented,
it is illustrated in them. If it hasn't been invented, then you'll find in them the nearest things
to what you want, some movements or devices that will apply in your case, perhaps; or which
will give you a key from which to work. No book or set of books ever published is of more real
value to the Inventor, Draftsman, or practical Mechanic than the two volumes described below.

Mechanical Movements, Powers, and Devices. By GARDNER D. Hiscox.

This is a collection of 1,890 engravings of different mechanical motions and appliances, ac-
companied by appropriate text, making it a book of great value to the inventor, the drafts-
man, and to all readers with mechanical tastes. The book is divided into eighteen sections
or chapters, in which the subject-matter is classified under 'the following heads: Mechanical
Powers; Transmission of Power; Measurement of Power; Steam Power; Air Power Appli-
ances; Electric Power and Construction; Navigation and Roads; Gearing; Motion and
Devices; Controlling Motion; Horological; Mining; Mill and Factory Appliances; Con-
struction and Devices; Drafting Devices; Miscellaneous Devices, etc. 15th Edition. 400
octavo pages. Price $3.00

Mechanical Appliances, Mechanical Movements and Novelties of Construc-
tion. By GARDNER D. Hiscox.

This is a supplementary volume to the one upon mechanical movements. Unlike the first
volume, which is more elementary in character, this volume contains illustrations and de-
scriptions of many combinations of motions and of mechanical devices and appliances found
in different lines of machinery, each device being shown by a line drawing with a description
showing its working parts and the method of operation. From the multitude of devices de-
scribed and illustrated might be mentioned, in passing, such items as conveyors and elevators,
Pony brakes, thermometers, various types of boilers, solar engines, oil-fuel burners, condensers,
evaporators, Corliss and other valve gears, governors, gas engines, water motors of various
descriptions, air ships, motors and dynamos, automobile and motor bicycles, railway lock
signals, car couplers, link and gear motions, ball bearings, breech-block mechanism for heavy
guns, and a large accumulation of others of equal importance. One thousand specially made
engravings. 396 octavo pages. Fourth edition. Price $3.00

Machine-Shop Tools and Shop Practice. By W. H. VANDERVOORT/

A work of 555 pages and 673 illustrations, describing in every detail the construction, opera
tion and manipulation of both hand and machine tools. Includes chapters on filing, fit-
ting and scraping surfaces; on drills, reamers, taps and dies; the lathe and its tools: planers,
shapers, and their tools; milling machines and cutters; gear cutters and gear cutting; drill-
ing machines and drill work; grinding machines and their work; hardening and tempering;
gearing, belting and transmission machinery; useful data and tables. Sixth edition.

Price $3.00

Machine- Shop Arithmetic. By COLVIN-CHENEY.

This is an arithmetic of the things you have to do with daily. It tells you plainly about:
how to find areas in figures; how to find surface or volume of balls or spheres; handy ways
for calculating; about compound gearing; cutting screw threads on any lathe; drilling for
taps; speeds of drills; taps, emery wheels, grindstones, milling cutters, etc.; all about the
Metric system with conversion tables; properties of metals; strength of bolts and nuts;
decimal equivalent of an inch. All sorts of machine-shop figuring and 1,001 other things,
any one of which ought to be worth more than the price of this book to you, as it saves you
the trouble of bothering the boss. 6th Edition. 131 pages. Price 50 Cents

Modern Machine-Shop Construction, Equipment and Management. By

OSCAR E. PERRIGO.

The only work published that describes the .Modern Shop or Manufacturing Plant from the
time the grass is growing on the site intended for it until the finished product is shipped. Just
the book needed by those contemplating the erection of modern shop buildings, the rebuilding
and reorganization of old ones, or the introduction of Modern Shop Methods, time and cost
systems. It is a book written and illustrated by a practical shop man for practical shop men
who are too busy to read theories and want facts. It is the most complete all-round book of
its kind ever published. Second Edition, Revised. 384 large quarto pages. 219 original and
specially made illustrations. 2nd Revised and Enlarged Edition. Price ....... $5 00

26 THE NORMAN W. HENLEY PUBLISHING CO.

Modern Milling Machines: Their Design, Construction, and Operation.

By JOSEPH G. HORNER.

This book describes and illustrates the Milling Machine and its .work in such a plain, clear
and forceful manner, and illustrates the subject so clearly and completely, that the up-to-
date machinist, student or mechanical engineer cannot afford to do without the valuable
information which it contains. It describes not only the early machines of this class, but notes
their gradual development into the splendid machines of the present day, giving the design
and construction of the various types, forms, and special features produced by prominent
manufacturers, American and foreign. 304 pages, 300 illustrations. Cloth. Price... $4.00

" Shop Kinks." By ROBERT GRIMSHAW.

A book of 400 pages and 222 illustrations, being entirely different from any other book on
machine-shop practice. Departing from conventional style, the author avoids universal
or common shop usage and limits his work to showing special ways of doing things better,
more cheaply and more rapidly than usual. As a result the advanced methods of represen-
tative establishments of the world are placed at the disposal of the reader. This book shows
the proprietor where large savings are possible, and how products may be improved. To
the employee it holds out suggestions that, properly applied, will hasten his advancement.
No shop can afford to be without it. It bristles with valuable wrinkles and helpful sugges-
tions. It will benefit all, from apprentice to proprietor. Every machinist, at any age, should
study its pages. Fifth edition. Price $2.50

Threads and Thread Cutting. By COLVIN and STABEL.

This clears up many of the mysteries of thread-cutting, such as double and triple threads,
internal threads, catching threads, use of hobs, etc. Contains a lot of useful hints and several
tables. Third edition. Price 25 cent S

MANUAL TRAINING

Economics of Manual Training. By Louis ROUILLION.

.The only book published that gives just the information needed by all interested in Manual
Training, regarding Buildings, Equipment, and Supplies. Shows exactly what is needed
for all grades of the work from the Kindergarten to the High and Normal School. Gives
itemized lists of everything used in Manual Training Work and tells just what it ought to
cost. Also shows where to buy supplies, etc. Contains 174 pages, and is fully illustrated.
Second edition. Price . ; $1.50

MARINE ENGINEERING

The Naval Architect's and Shipbuilder's Pocket Book of Formulae, Rules,
and Tables and Marine Engineer's and Surveyor's Handy Book of
Reference. By CLEMENT MACKROW and LLOYD WOOLLARD.

The eleventh Revised and Enlarged Edition of this most comprehensive work has just been
issued. It is absolutely indispensable to all engaged in the Shipbuilding Industry, as it con-
denses into a compact form all data and formulae that are ordinarily required. The book is
completely up to date, including among other subjects a section on Aeronautics. 750 pages,
limp leather binding. Price $5.00 net

Marine Engines and Boilers: Their Design and Construction. By DR. G.

BAUER, LESLIE S. ROBERTSON and S. BRYAN DONKIN.

In the words of Dr. Bauer, the present work owes its origin to an oft felt want of a condensed
treatise embodying the theoretical and practical rules used in designing marine engines and
boilers. The need of such a work has been felt by most engineers engaged m the construction
and working of marine engines, not only by the younger men, but also by those of greater ex-
perience. The fact that the original German work was written by the chief engineer ot the
famous Vulcan Works, Stettin, is in itself a guarantee that this book is m all respects thor-
oughly up-to-date, and that it embodies all the information which is necessary for the design
and construction of the highest types of marine engines and b9ilers. It may be said that the
motive power which Dr. Bauer has placed in the fast German liners that have been turned out
of late years from the Stettin Works represent the very best practice in marine engineering ot
the present day. The work is clearly written, thoroughly systematic, theoretically sound;
while the character of the plans, drawings, tables, and statistics is without reproach. Ine
illustrations are careful reproductions from actual working drawings, with some well- executed
photographic views of completed engines and boilers. 744 pages, 550 illustrations and num-
erous tables. Cloth. Price $9.00 net

CATALOGUE OF GOOD, PRACTICAL BOOKS 27

MINEYG

Ore Deposits, with a Chapter on Hints to Prospectors. By J. P. JOHNSON.

This book gives a condensed account of the ore deposits at present known in South Africa.
It is also intended as a guide to the prospector. Only an elementary knowledge of geology
and some mining experience are necessary in order to understand this work. With these
qualifications, it will materially assist one in his search for metalliferous mineral occurrences
and, so far as simple ores are concerned, should enable one to form some idea of the possi-
bilities of any he may find. Illustrated. Cloth. Price $2 00

Practical Coal Mining. By T. H. COCKIN.

An important work, containing 428 pages and 213 illustrations, complete with practical details,
which will intuitively impart to the reader not only a general knowledge of the principles
of coal mining, but also considerable insight into allied subjects. The treatise is positively
up-to-date in every instance, and should be in the hands of every colliery engineer, geologist,
mine operator, superintendent, foreman, and all others who are interested in or connected with
the industry. 3d Edition. Cloth. Price $2.50

Physics and Chemistry of Mining. By T. H. BYROM.

A practical work for the use of all preparing for examinations in mining or qualifying for
colliery managers' certificates. The aim of the author in this excellent book is to place clearly
before the reader useful and authoritative data which will render him valuable assistance in
his studies. The only work of its kind published. The information incorporated in it will
prove of the greatest practical utility to students, mining engineers, colliery managers, and
all others who are specially interested in the present-day treatment of mining problems. 160
pages, illustrated. Price $2.00

PATTERN MAKING

Practical Pattern Making. By F. W. BARROWS.

This book, now in its second edition, is a comprehensive and entirely practical treatise on the
subject of pattern making, illustrating pattern work in both wood and metal, and with definite
instructions on the use of plaster of parts in the trade. It gives specific and detailed descrip-
tions of the materials used by pattern makers, and describes the tools, both those for the
bench and the more interesting machine tools, having complete chapters on the Lathe, the
Circular Saw, and the Band Saw. It gives many examples of pattern work, each one fully
illustrated and explained with much detail. These examples, in their great variety, offer much
that will be found of interest to all pattern makers, and especially to the younger ones, who
are seeking information on the more advanced branches of their trade.

In this second edition of the work will be found much that is new, even to those who have
long practised this exacting trade. In the description of patterns as adapted to the Moulding
Machine many difficulties which have long prevented the rapid and economical production of
castings are overcome; and this great, new branch of the trade is given much space. Strip-
ping plate and stool plate work and the less expensive vibrator, or rapping plate work, are
all explained in detail.

Plain, every-day rules for lessening the cost of patterns, with a complete system of cost
keeping, a detailed method of marking, applicable to all branches of the trade, with com-
plete information showing what the pattern is, its specific title, its cost, date of production,
material of which it is made, the number of pieces and core-boxes, and its location in the
pattern safe, all condensed into a most complete card record, with cross index.
The book closes with an original and practical method for the inventory and valuation of
patterns. Containing nearly 350 pages and 170 illustrations. Price $2*00

PERFUMERY

Perfumes and Cosmetics: Their Preparation and Manufacture. By G. W.

ASKINSON, Perfumer.

A comprehensive treatise, in which there has been nothing omitted that could be of value
to the perfumer or manufacturer of toilet preparations. Complete directions for making
handkerchief perfumes, smelling-salts, sachets, fumigating pastilles; preparations for the
care of the skin, the mouth, the hair, cosmetics, hair dyes and other toilet articles are given,
also a detailed description of aromatic substances; their nature, tests of purity, and whole-
some manufacture, including a chapter on synthetic products, with formulas for their use.
A book of general as well as professional interest, meeting the wants not only of the drug-

rt and perfume manufacturer, but also of the general public. Among the contents are:
The History of Perfumery. 2. About Aromatic Substances in General. 3. Odors from
the Vegetable Kingdom. 4. The Aromatic Vegetable Substances Employed in Perfumery.
5. The Animal Substances Used in Perfumery. 6. The Chemical Products Used in Perfumery.
7. The Extraction of Odors. 8. The Special Characteristics of Aromatic Substances. 9. The
Adulteration of Essential Oils and Their Recognition. 10. Synthetic Products. 11. Table
of Physical Properties of Aromatic Chemicals. 12. The Essences or Extracts Employed
in Perfumery. 13. Directions for Making the Most Important Essences and Extracts.

28 THE NORMAN W. HENLEY PUBLISHING CO.

14. The Division of Perfumery. 15. The Manufacture of Handkerchief Perfumes. 16. For-
mulas for Handkerchief Perfumes. " 17. Ammoniacal and Acid Perfumes. 18. Dry Per-
fumes. 19. Formulas for Dry Perfumes. 20. The Perfumes Used for Fumigation. 21. An-
tiseptic and Therapeutic Value of Perfumes. 22. Classification of Odors. 23. Some Special
Perfumery Products. 24. Hygiene and Cosmetic Perfumery. 25. Preparations for the Care
of the Skin. 26. Manufacture of Casein. 27. Formulas for Emulsions. 28. Formulas for
Cream. 29. Formulas for Meals, ' Pastes and Vegetable Milk. 30. Preparations Used for
the Hair. 31. Formulas for Hair Tonics and Restorers. 32. Pomades and Hair Oils.
33. Formulas for the Manufacture of Pomades and Hair Oils. 34. Hair Dyes and Depila-
tories. 35. Wax Pomades, Bandolines and Bri'lliantines. 36. Skin Cosmetics and
Face Lotions. 37. Preparations for the Nails. 38. Water Softeners and Bath Salts. 39.
Preparations for the Care of the Mouth. 40. The Colors Used in Perfumery. 41. The Uten-
sils Used in the Toilet. Fourth edition, much enlarged and brought up to date. Nearly
400 pages, illustrated. Price $5.00

WHAT IS SAID OF THIS BOOK:

"The most satisfactory work on the subject of Perfumery that we have ever seen."
"We feel safe in saying that. here is a book on Perfumery that will not disappoint you, for
it has practical and excellent formulae that are within your ability to prepare readily."
"We recommend the volume as worthy of confidence, and say that no purchaser will be dis-
appointed in securing from its pages good value for its cost, and a large dividend on the same,
even if he should use but one per cent, of its working formulae. There is money in it for every
user of its information." Pharmaceutical Record.

PLUMBING

Mechanical Drawing for Plumbers. By R. M. STAEBUCK.

A concise, comprehensive and practical treatise on the subject of mechanical drawing in its
various modern applications to the work of all who are in any way connected with the plumb-
ing trade. Nothing will so help the plumber in estimating and in explaining work to cus-
tomers and workmen as a knowledge of drawing, and to the workman it is of inestimable
value if he is to rise above his position to positions of greater responsibility. Among the
chapters contained are: 1. Value to plumber of knowledge of drawing; tools required and
their use; common views needed in mechanical drawing. 2. Perspective versus mechanical
drawing in showing plumbing construction. 3. Correct and incorrect methods in plumbing
drawing; plan and elevation explained. 4. Floor and cellar plans and elevation; scale
drawings; use of triangles. 5. Use of triangles; drawing of fittings, traps, etc. 6. Drawing
plumbing elevations and fittings. 7. Instructions in drawing plumbing elevations. 8. The
drawing of plumbing fixtures; scale drawings. 9. Drawings of fixtures and fittings. 10. Ink-
ing of drawings. 11. Shading of drawings. 12. Shading of drawings. 13. Sectional drawings;
drawing of threads. 14. Plumbing elevations from architect's plan. 15. Elevations of sepa-
rate parts of the plumbing system. 16. Elevations from the architect's plans. 17. Drawings
of detail plumbing connections. 18. Architect's plans and plumbing elevations of residence.
19. Plumbing elevations of residence (continued); plumbing plans for cottage. 20. Plumbing
elevations; 'roof connections. 21. Plans and plumbing elevations for six-flat building. 22.
Drawing of various parts of the plumbing system; use of scales. 23. Use of architect's scales.
24. Special features in the illustrations of country plumbing. 25. Drawing of wrought-iron
piping, valves, radiators, coils, etc. 26. Drawing of piping to illustrate heating systems.
150 illustrations. Price $1.50

Modern Plumbing Illustrated. By R. M. STARBUCK.

This book represents the highest standard of plumbing work. It has been adopted and used
as a reference book by the United States Government in its sanitary work in Cuba, Porto
Rico and the Philippines, and by the principal Boards of Health of the United States and
Canada.

It gives connections, sizes and working data for all fixtures and groups of fixtures. It is help-
ful to the master plumber in demonstrating to his customers and in figuring work. It gives
the mechanic and student quick and easy access to the best modern plumbing practice. Sug-
gestions for estimating plumbing construction are contained in its pages. This book repre-
sents, in a word, the latest and best up-to-date practice and should be in the hands of every
architect, sanitary engineer and plumber who wishes to keep himself up to the minute on
this important feature of construction. Contains following chapters, each illustrated with a
full-page plate: Kitchen sink, laundry tubs, vegetable wash sink; lavatories, pantry sinks,
contents of marble slabs; bath tub, foot and sitz bath, shower bath; water closets, venting
of water closets; low-down water closets, water closets operated by flush valves, water closet
range; slop sink, urinals, the bidet; hotel and restaurant sink, grease trap; refrigerators,
safe wastes, laundry waste, lines of refrigerators, bar sinks, soda fountain sinks; horse stall,
frost-proof water closets; connections for S traps, venting; connections for drum traps;
soil-pipe connections; supporting of soil pipe; main trap and fresh-air inlet; floor drains and
cellar drains, subsoil drainage; water closets and floor connections; local venting; connections
for bath rooms; connections for bath rooms, continued; examples of poor practice; roughing
work ready for test; testing of plumbing systems; method of continuous venting; continuous
venting for two-floor work; continuous venting for two lines of fixtures on three or more
floors; continuous venting of water closets; plumbing for cottage house; construction for
cellar piping; plumbing for residence, use of special fittings; plumbing for two-flat house;
plumbing for apartment building", plumbing for double apartment building; plumbing for
office building; plumbing for public toilet rooms; plumbing for public toilet rooms, con-
tinued; plumbing for bath establishment; plumbing for engine house, factory plumbing;
automatic flushing for schools, factories, etc.; use of flushing valves; urinals for public toilet
rooms; the Durham system, the destruction of nines bv electrolysis; construction of work

CATALOGUE OF GOOD, PRACTICAL BOOKS 29

without use of lead; automatic sewage lift; automatic sump tank; country plumbing;
construction of cesspools; septic tank and automatic sewage siphon; water supply for
country house; thav/ing of water mains and service by electricity; double boilers; hot
water supply of lar^e buildings; automatic control of hot-water tank; suggestions for
estimating plumbing construction. 407 ootavo pages, fully illustrated by 57 full-page
engravings. Third, revised and enlarged edition, just issued. Price $4.00

Standard Practical Plumbing. By R. M. STARED CK.

A complete practical treatise of 450 pages, covering the subject of Moderr Plumbing in al> its
branches, a large amount of space being devoted to a very complete and practical treatment of
the subject of Hot Water Supply and Circulation and Range Boiler Work. Its thirty Chapters
include about every phase of the subject one can think of, making it an ii.dispenEabif> work to
the master plumber, the journeyman plumber, and the apprentice plumber, containing chap-
ters on: the plumber's tools; wiping solder; composition and use; joint wiping; lead work;
traps; siphonage of traps; venting; continuous venting; house sewer and sewer connections;
house drain; soil piping, roughing; main trap and fresh air inlet; floor, yard, cellar drains,
rain leaders, etc. ; fixture wastes; water closets; ventilation; improved plumbing connections;
residence plumbing; plumbing for hotels* schools, factories, stables, etc.; modern country
plumbing; filtration of sewage and water supply ' hot and cold supply; range boilers; circula-
tion; circulating pipes; range boiler problems; hot water for large buildings; water lift and
its use; multiple connections for hot water boilers; heating of radiation by supply system;
theory for the plumber; drawing for the plumber. Fully illustrated by 347 engravings.

$3.00

RECIPE BOOK

Henley's Twentieth Century Book of Recipes, Formulas and Processes.

Edited by GARDNER D. Hiscox.

The most valuable Tecbno-chemical Formula Book published, including over 10,000 selected
scientific, chemical, technological, and practical recipes and processes.

This is. the most complete Book of Formulas ever published, giving thousands of recipes for
the manufacture of valuable articles for everyday use. Hints, Helps, Practical Ideas, and
Secret Processes are revealed within its pages. It covers every branch of the useful arts and
tells thousands of ways of making money, and is just the book everyone should have at his
command.

Modern in its treatment of every subject that properly falls within its scope, the book may
truthfully be said to present the very latest formulas to be found in the arts and industries,
and to retain those processes which long experience has proven worthy of a permanent record.
TO present here even a limited number of the subjects which find a place in this valuable work
would be difficult. Suffice to say that in its pages will be found matter of intense interest and
immeasurably practical value to the scientific amateur and to him who wishes to obtain a
knowledge of the many processes used in the arts, trades and manufacture, a knowledge
which will render his pursuits more instructive and remunerative. Serving as a
reference book to the small and large manufacturer and supplying intelligent seekers with the
information necessary to conduct a process, the work will be found of inestimable worth to
the Metallurgist, the Photographer, the Perfumer, the Painter, the Manufacturer of Glues,
Pastes, Cements, and Mucilages, the Compounder of Alloys, the Cook, the Physician, the
Druggist, the Electrician, the Brewer, the Engineer, the Foundryman, the Machinist, the
Potter, the Tanner, the Confectioner, the Chiropodist, the Manicurist, the Manufacturer of
Chemical Novelties and Toilet Preparations, the Dyer, the Electroplater, the Enameler, the
Engraver, the Provisioner, the Glass Worker, the Goldbeater, the Watchmaker, the Jeweler,
the Hat Maker, the Ink Manufacturer, the Optician, the Farmer, the Dairyman, the Paper
Maker, the Wood and Metal Worker, the Chandler and Soap Maker, the Veterinary Surgeon,
and the Technologist in general.

A mine of information, and up-to-date"in every respect. A book which will prove of value
to EVERYONE, as it covers every branch of the Useful Arts. Every home needs this book;
every office, every factory, every store, every public and private enterprise EVERYWHERE
should have a copy. 800 pages. Price $3.00

WHAT IS SAID OF THIS BOOK:

"Your Twentieth Century Book of Recipes, Formulas, and Processes duly received. I am
glad to have a copy of it, and if I could not replace it, money couldn't buy it. It is the best
thing of the sort I ever saw." (Signed) M. E. TRUX, Sparta, Wis.

" There are few persons who would not be able to find in the book some single formula that
would repay several times the cost of the book." Merchants' Record and Show Window.

" I purchased your book, ' Henley's Twentieth Century Book of Recipes, Formulas and Proc-
esses,' about a year ago and it is worth its weight in gold." WM. H. MURRAY, Bennington, Vt.

"ONE OF THE WORLD'S MOST USEFUL BOOKS"

"Some time ago I got one of your 'Twentieth Century Books of Foitnulas,' and have made
my living from it ever since. I am alone since my husband's death with two small children
to care for and am trying so hard to support them. I have customers who take from me
Toilet Articles I put up, following directions given in the book, and I have found everyone of
them to be fine." MRS. J. H. MCMAKEN, West Toledo, Ohio.

30 THE NORMAN W. HENLEY PUBLISHING CO.

RUBBER

Rubber Hand Stamps and the Manipulation of India Rubber. By T.

O'CONOR SLOANE.

This book gives full details on all points, treating in a concise and simple manner the elements
of nearly everything it is necessary to understand for a commencement in any branch of the
India Rubber Manufacture. The making of all kinds of Rubber Hand Stamps, Small Articles
of India Rubber, U. S. Government Composition, Dating Hand Stamps, the Manipulation of
Sheet Rubber, Toy Balloons, India Rubber Solutions, Cements, Blackings, Renovating,
Varnish, and Treatment for India Rubber Shoes, etc.; the Hektograph Stamp Inks, and Mis-
cellaneous Notes, with a Short Account of the Discovery, Collection and Manufacture of India
Rubber, are set forth in a manner designed to be readily understood, the explanations being
plain and simple. Including a chapter on Rubber Tire Making and Vulcanizing; also a
chapter on the uses of rubber in Surgery and Dentistry. 3rd Revised and Enlarged Edition.
175 pages. Illustrated $1.00

SAWS

Saw Filing and Management of Saws. By ROBERT GRIMSHAW.

A practical hand-book on filing, gumming, swaging, hammering, and the brazing of band
Baws, the speed, work, and power to run circular saws, etc. A handy book for those who have
charge of saws, or for those mechanics who do their own filing, as it deals with the proper
shape and pitches of saw teeth of all kinds and gives many useful hints and rules for gumming,
setting, and filing, and is a practical aid to those who use saws for any purpose. Complete
tables of proper shape, pitch, and saw teeth as well as sizes and number of teeth of various
saws are included. 3rd Edition, Revised and Enlarged. Illustrated. Price $1.00

STEAM ENGINEERING

American Stationary Engineering. By W. E. CRANE.

This book begins at the boiler room and takes in the whole power plant. A plain talk on
eyery-day work about engines, boilers, and their accessories. It is not intended to be scien-
tific or mathematical. All formulas are in simple form so that any one understanding plain
arithmetic can readily understand any of them. The author has made this the most practical
book in print; has given the results of his years of experience, and has included about all that
has to do with an engine room or a power plant. You are not left to guess at a single point.
You are shown clearly what to expect under the various conditions; how to secure the best
results; ways of preventing "shut downs" and repairs; in short, all that goes to make up the
requirements of a good engineer, capable of taking charge of a plant. It's plain enough, for
practical men and yet of yalue to those high in the profession.

A partial list of contents is: The boiler room, cleaning boilers, firing, feeding; pumps, inspec-
tion and repair ; chimneys, sizes and cost; piping; mason work; foundations; testing cement;

tools; pistons and piston rings; bearing metal; hardened copper; drip pipes from cylinder
jacket; belts, how made, care of; oils; greases; testing lubricants; rules and tables, in-
cluding steam tables; areas of segments; squares and square roots; cubes and cube root;
areas and circumferences of circles. Notes on: Brick work; explosions; pumps; pump
valves; heaters, economizers; safety valves; lap, lead, and clearance. Has a complete ex-
amination for a license, etc., etc. 3rd Edition. 345 pages, illustrated. Price . . .

Engine Runner's Catechism. By ROBERT GRIMSHAW.

A practical treatise for the stationary engineer, telling how to erect, adjust, and run the
principal steam engines in use in the United States. Describing the principal features of vari-
ous special and well-known makes of engines: Temper Cut-off, Snipping and Receiving Founda-
tions, Erecting and Starting, Valve Setting, Care and Use, Emergencies, Erecting and Ad-
justing Special Engines.

The questions asked throughout the catechism are plain and to the point, and the answers
are given in such simple language as to be readily understood by anyone. All the instructions
given are complete and up-to-date; and they are written in a popular style, without any
technicalities or mathematical formulae. The work is of a handy size for the pocket, clearly
and well printed, nicely bound, and profusely illustrated.

To young engineers this catechism will be of great value, especially to those who may bg
preparing to go forward to be examined for certificates of competency; and to engineers
generally it will be of no little service, as they will find in this volume more really practical
and useful information than is to be found anywhere else within a like compass. 387 pages.
7th Edition. Price ................ .............. $2.00

CATALOGUE OF GOOD, PRACTICAL BOOKS 31

Modern Steam Engineering in Theory and Practice. By GARDNER D.
Hiscox.

This is a complete and practical work issued for Stationary Engineers and Firemen, dealing
with the care and management of boilers, engines, pumps, superheated steam, refrigerating
machinery, dynamos, motors, elevators, air compressors, and all other branches with which
the modern engineer must be familiar. Nearly 200 questing with their answers on steam
and electrical engineering, likely to be asked by the Examining Board, are included.
Among the chapters are: Historical: steam and its properties; appliances for the generation
of steam; types of boilers; chimney and its work; heat economy of the feed water; steam
pumps and their work; incrustation and its work; steam above atmospheric pressure; flow
of steam from nozzles; superheated steam and its work; adiabatic expansion of steam; indi-
cator and its work; steam engine proportions; slide valve engines and valve motion; Corliss
engine and its valve gear; compound engine and its theory; triple and multiple expansion
engine; steam turbine; refrigeration; elevators and their management;. cost of power; steam
engine troubles; electric power and electric plants. 487 pages, 405 engravings. 3rd Edition.
Price $3.00

Steam Engine Catechism. By ROBERT GRIMSHAW.

This unique volume of 413 pages is not only a catechism on the question and answer principle
but it contains formulas and worked-out answers for all the Steam problems that appertain to
operation and management of the Steam Engine. Illustrations of various valves and valve
gear with their principles of operation are given. Thirty-four Tables that are indispensable
to every engineer and fireman that wishes to be progressive and is ambitious to become master
of his calling are within its pages. It is a most valuable instructor in the service of Steam
Engineering. Leading engineers have recommended it as a valuable educator for the begin-
ner as well as a reference book for the engineer. It is thoroughly indexed for every detail.
Every essential question on the Steam Engine with its answer is contained in this valuable
work. 16th Edition. Price : 82.00

Steam Engineer's Arithmetic. By COLVIN-CHENEY.

A practical pocket-book for the steam engineer. Shows how to work the problems of the
engine room and shows "why." Tells how to figure horsepower of engines and boilers; area
of boilers; has tables of areas and circumferences; steam tables; has a dictionary of engineering
terms. Puts you on to all of the little kinks in figuring whatever there is to figure around a
power plant. Tells you about the heat unit; absolute zero; adiabatic expansion; duty of
engines; factor of safety; and a thousand and one other things; and everything is plain and
simple not the hardest way to figure, but the easiest. 2nd Edition. Price . . 50 Cents

Engine Tests and Boiler Efficiencies. By J. BUCHETTI.

This work fully describes and illustrates the method of testing the power of steam engines,
turbines and explosive motors. The properties of steam and the evaporative power of fuels.
Combustion of fuel and chimney draft; with formulas explained or practically computed.
255 pages, 179 illustrations. Price $3.00

Horsepower Chart.

Shows the horsepower, of any stationary engine without calculation. No matter what the
cylinder diameter of stroke, the steam pressure of cut-off, the revolutions, or whether con-
densing or non-condensing, it's all there. Easy to use, accurate, and saves time and calcula-
tions. Especially useful to engineers and designers. Price 50 Cents

STEAM HEATING AND VENTILATION

Practical Steam, Hot-Water Heating and Ventilation. By A. G. KING.

This book is the standard and latest work published on the subject and has been prepared for
the use of all engaged in the business of steam, hot-water heating, and ventilation. It is an
original and exhaustive work. Tells how to get heating contracts, how to install heating and
ventilating apparatus, the best business methods to be used, with "Tricks of the Trade" for
shop use. Rules and data for estimating radiation and cost and such tables and information
as make it an indispensable work for everyone interested in steam, hot-water heating, and
ventilation. It describes all the principal systems of steam, hot-water, vacuum, vapor, and
vacuum-vapor heating, together with the new accelerated systems of hot-water circulation,
including chapters on up-to-date methods of ventilation and the fan or blower system of heat-
ing and ventilation. Containing chapters on: I. Introduction. II. Heat. III. Evolution
of artificial heating apparatus. IV. Boiler surface and settings. V. The chimney flue.
VI. Pipe and fittings. VII. Valves, various kinds. VIII. Forms of radiating surfaces. IX.

32 THE NORMAN W. HENLEY PUBLISHING CO.

Locating of radiating surfaces. X. Estimating radiation. XI. Steam-heating apparatus.
XII. Exhaust-steam heating. XIII. Hot-water, heating. XIV. Pressure systems of hot-water
work. XV. Hot-water appliances. XVI. Greenhouse heating. XVII. Vacuum vapor and
vacuum exhaust heating. XVIII. Miscellaneous heating. XIX. Radiator and pipe connec-
tions. XX. Ventilation. XXI. Mechanical ventilation and hot-blast heating. XXII.
Steam appliances. XXIII. District heating. XXIV. Pipe and boiler covering. XXV. Tem-
perature regulation and heat control. XXyi. Business methods. XXVII. Miscellaneous.
XXVIII. Rules, tables, and useful information. 367 pages, 300 detailed engravings. 2nd
Edition Revised. Price $3.00

Five Hundred Plain Answers to Direct Questions on Steam, Hot-Water,
Vapor and Vacuum Heating Practice. By ALFRED G. KING.

This work, jnst off the press, is arranged in question and answer form; it is intended as a
guide and text-book for the younger, inexperienced fitter and as a reference book for all
fitters. This book tells "how" and also tells "why". No work of its kind has ever been
published. It answers all the questions regarding each method or system that would be
asked by the steam fitter or heating contractor, and may be used as a text or reference book,
and for examination questions by Trade Schools or Steam Fitters' Associations. Rules, data,
tables and descriptive methods are given, together with much other detailed information of
daily practical use to those engaged in or interested in the various methods of heating. Val-
uable to those preparing for examinations. Answers every question asked relating to modern
Steam, Hot-Water, Vapor and Vacuum Heating. Among the contents are: The Theory and
Laws of Heat. Methods of Heating. Chimneys and Flues. Boilers for Heating. Boiler
Trimmings and Settings. Radiation. Steam Heating. Boiler, Radiator and Pipe Connec-
tions for Steam Heating. Hot Water Heating. The Two-Pipe Gravity System of Hot Water
Heating. The Circuit System of Hot Water Heating. The Overhead System of Hot Water
Heating. Boiler, Radiator and Pipe Connections for Gravity Systems of Hot Water Heat-
ing. Accelerated Hot Water Heating. Expansion Tank Connections. Domestic Hot Water
Heating. Valves and Air Valves. Vacuum Vapor and Vacuo-Vapor Heating. Mechanical
Systems of Vacuum Heating. Non-Mechanical Vacuum Systems. Vapor Systems. Atmos-
pheric and Modulating Systems. Heating Greenhouses. Information, Rules and Tables.
200 pages, 127 illustrations. Octavo. Cloth. Price $1 .50

STEEL

Steel: Its Selection, Annealing, Hardening, and Tempering. By E. R.

MARKHAM.

This work was formerly known as "The American Steel Worker," but on the publication
of the new, revised edition, the publishers deemed it advisable to change its title to a more
suitable one. It is the standard work on Hardening, Tempering, and Annealing Steel of all kinds.
This book tells how to select, and how to work, temper, harden, and anneal steel for every-
thing on earth. It doesn't tell how to temper one class of tools and then leave the treatment
of another kind of tool to your imagination and judgment, but it gives careful instructions
for every detail of every tool, whether it be a tap, a reamer or just a screw-driver. It tells
about the tempering of small watch springs, the hardening of cutlery, and the annealing of
dies. In fact, there isn't a thing that a steel worker would want to know that isn't included.
It is the standard book on selecting, hardening and tempering all grades of steel. Among
the chapter headings might be mentioned the following subjects: Introduction; the work-
man; steel; methods of heating; heating tool steel; forging; annealing; hardening baths;
baths for hardening; hardening steel; drawing the temper ^ after hardening; examples of
hardening; pack hardening; case hardening; spring tempering; making tools of machine
steel; special steels; steel for various tools; causes of trouble; high-speed steels, etc. 400
pages. Very fully illustrated. Fourth edition. Price $2.50

Hardening, Tempering, Annealing, and Forging of Steel. By J. V. WOOD-
WORTH.

A new work treating in a clear, concise manner all modern processes for the heating, anneal-
ing, forging, welding, hardening and tempering of 'steel, making it a book of great practical
value to the metal-working mechanic in general, with special directions for the successful
hardening and tempering of all steel tools used in the arts, including milling cutters, taps, thread
dies, reamers, both solid and shell, hollow mills, punches and dies, and all kinds of sheet-
metal working tools, shear blades, saws, fine cutlery, and metal-cuttina; tools of all descrip-
tion, as well as for all implements of steel both large and small. In this work the simplest
and most satisfactory hardening and tempering processes are given.

The uses to which the leading brands of steel may be adapted are concisely presented, and
their treatment for working under different conditions explained, also the special methods
for the hardening and tempering of special brands.

A chapter devoted to the different processes for case-hardening is also included, and special
reference made to the adaptation of machinery steel for tools of various kinds. Fourth edi-
tion. 288 pages. 201 illustrations. Price $2.50

CATALOGUE OF GOOD, PRACTICAL BOOKS 33
TRACTORS

The Modern Gas Tractor. By VICTOR W. PAGE, M.E.

A complete treatise describing all types and sizes of gasoline, kerosene and oil tractors. Con-
siders design and construction exhaustively, gives complete instructions for care, operation
and repair, outlines all practical applications on the road and in the field. The best and
latest work on farm tractors and tractor power plants. A work needed by farmers, students,
blacksmiths, mechanics, salesmen, implement dealers, designers, and engineers. Second edition,
revised and enlarged. 504 pages. Nearly 300 illustrations and folding plates. Price $2.00

TURBINES

Marine Steam Turbines. By DR. G. BAUER and O. LASCHE. Assisted by
E. LUDWIG and H. VOGEL.

Translated from the German and edited by M. G. S. Swallow. The book is essentially prac-
tical and discusses turbines in which the full expansion of ste^am passes through a number
of separate turbines arranged for driving two or more shafts, as in the Parsons system, and
turbines in which the complete expansion of steam from inlet to exhaust pressure occurs in
a turbine on one shaft, as in the case of the Curtis machines. It will enable a designer to
carry out all the ordinary calculation necessary for the construction of steam turbines, hence
it fills a want which is hardly met by larger and more theoretical works. Numerous tables,
curves and diagrams will be found, which explain with remarkable lucidity the reason why
turbine blades are designed as they are, the course which steam takes through turbines of
various types, the thermodynamics of steam turbine calculation, the influence of vacuum
on steam consumption of steam turbines, etc. In a word, the very information which a de-
signer and builder of steam turbines most requires. Large octavo, 214 pages. Fully illustrated
and containing eighteen tables, including an entropy chart. Price, net $3.50

WATCH MAKING

Watchmaker's Handbook. By CLAUDIUS SAUNIER.

No work issued can compare with this book for clearness and completeness. It contains
498 pages and is intended as a workshop companion for those engaged in watch-making and
allied mechanical arts. Nearly 250 engravings and fourteen plates are included. This is
the standard work on watch-making. Price $3 .00

WELDING

Automobile Welding with the Oxy- Acetylene Flame. By M. KEITH DUNHAM.

Explains in a simple manner apparatus to be used, its care, and how to construct necessary
shop equipment. Proceeds then to the actual welding of all automobile parts, in a manner
understandable by every one. Gives principles never to be forgotten. Aluminum, cast iron,
steel, copper, brass, bronze, and malleable iron are fully treated, as well as a clear explana-
tion of the proper manner to burn the carbon out of the combustion head. This book is of
utmost value, since the perplexing problems arising when metal is heated to a melting point
are fully explained and the proper methods to overcome them shown. 167 pages, fully illus-
trated. Price $1.00

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A MONTHLY magazine devoted to practical mechanics for everyday men.
Its aim is to popularize engineering as a science, teaching the elements
of applied mechanics and electricity in a straightforward and understand-
able manner. The magazine maintains its own experimental laboratory where
the devices described in articles submitted to the Editor are first tried out and
tested before they are published. This important innovation places the standard
of the published material very high, and it insures accuracy and dependability.

The magagine is the only one in this country that specializes in practical
model building. Articles in past issues have given comprehensive designs for
many model boats, including submarines and chasers, model steam and gasoline
engines, electric motors and generators, etc., etc. This feature is a permanent
one in this magazine.

Another popular department is that devoted to automobiles and airplanes.
Care, maintenance, and operation receive full and authoritative treatment. Every
article is written from the practical, everyday-man, standpoint rather than from
that of the professional.

The magazine entertains while it instructs. It is a journal of practical, de-
pendable information given in such a style that it may be readily assimilated
and applied by the man with little or no technical training. The aim is to place
before the man who leans toward practical mechanics, a series of concise, crisp,
readable talks on what is going on and how it is done. These articles are profusely
illustrated with clear, snappy photographs, specially posed to illustrate the subject
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UNIVERSITY OF CALIFORNIA LIBRARY
BERKELEY

Return to desk from which borrowed.
This book is DUE on the last date stamped below.

NGINEER1NG LIBR/

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NO*' 27 1953

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UNIVERSITY OF CALIFORNIA LIBRARY