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fundamentals of 


1964 Reprint 


© J959, 1962, 1964, by the Institute of Aviation of the University of Illinois 
Manufactured in the United States of America 
Library of Congress Catalog Card No. 64-23260 


In 1945 Mr. Edwin A. Link, inventor of the Link 
Might trainer and electronic simulators, and his 
company. Link Aviation, Inc., sponsored the publica- 
tion of a book written by Norman Potter and William 
J. Konicek of the Link staff. The book was called 
"Fundamentals of Aviation" and was an immediate 
success. Since that first publication, Mr. Link has 
signally benefited aviation by establishing The Link 
Foundation, which is dedicated to the advancement 
of education and training in aeronautics. 

In 1955 the staff of the Institute of Aviation of the 
University of Illinois revised the book. It was com- 
pletely rewritten and enlarged in 1959 by those mem- 
bers of the University staff whose names appear as 
co-authors on the title page and the title was changed 
to "Fundamentals of Aviation and Space Technology." 

The interest of The Link Foundation and Dr. Frank 
E. Sorenson, then Executive Secretary of the Founda- 
tion, and of Miss Marilyn C. Link, made the 1959 
edition possible. However, the authors had complete 
freedom in the selection of materials and assume sole 
responsibility therefor. 

Mr. James NT Hancock acted as coordinator. Mr. 
Robert L. Ayers, Mr. Thomas H. Bailey, Mr. Hale C. 
Bartlett, Mrs. Gertrude A. Becker, and Mr. Thomas 
H. Gordon, also of the Institute of Aviation staff, 
contributed materially to the manuscript. 

The reception accorded the first edition of this book 
under its present title was very gratifying. It appealed 
^especially to teachers and students, as well as to the 
air transportation industry for orientation courses. 

The book was reprinted in 1962, with a few revisions 
being made to update and clarify the content, and 
a chapter added on developments in space explora- 
tion. The continued success of the book has again 
exhausted the supply, and a new printing is necessary 
only two years after the previous revision. Statistics 
and other items have been updated and the glossary 
expanded. Also, the chapters on the Federal Aviation 
Agency and Space Exploration have been revised to 
reflect recent changes and developments. For the 
benefit of libraries and others who wish hard covers, 
the book is available in such covers. 

It is a pleasure to acknowledge again the coopera- 
tion of The Link Foundation, particularly of Miss 
Marilyn Link, Executive Secretary, and Dr. Frank 
E. Sorenson, Chairman of the Technical Assistance 
Board. Mr. James M. Hancock, who is now Execu- 
tive Director of the Chicago Planetarium Society, has 
acted as coordinator of the revision. Their assistance 
has been invaluable. 

As Mr. Link wrote in the first edition of the book, 
"With a full realii;ation of the wide influence of 
aviation on the peoples of the world; with an under- 
standing of the problems which youth will face grow- 
ing up in the air age; and with a profound belief in, 
and respect for, the processes of education meeting 
this challenge, we respectfully dedicate this aviation 
publication to all American youth." 

Leslie A. Bryan 
Lhhana, Illinois Director, Institute of Aviation 

June 1964 University of Illinois 


The Economic Aspect 1 

Aerospace Manufacturing Industry 2 

Air Transport Industry 3 

General Aviation 6 
The Social Aspect 6 

Population Distribution 7 

Education 7 

Family Life 7 
The Political Aspect 7 

Military Operations 7 

International Affairs 8 

Politics 9 
Summary 9 

Balloons and Gliders 1 1 
Experiments of the Wright Brothers 1 2 
Man's First Flight 13 
Later Developments 1 3 
Air-Mail and Air-Passenger Transportation 
Summary 1 4 

Shape of the Wing 16 
Speed of the Wing 16 
Lift and Angle of Attack 17 
Lift and Weight 17 
Thrust and Drag 1 7 
Inherent Stability 18 
The Axes of Rototion 1 9 
Rudder 19 
Elevators 20 
Ailerons 20 

Coordination of Controls 20 
Trim Tabs 20 
Summary 22 


General Structure of an Airplane 24 

Wings 26 

Fuselage 27 

Tail Assembly 27 

Landing Gear 29 

Powerplants 30 

Propellers 30 

Jet Propulsion 31 

Airplane Accessories 32 


Other Aircraft Types 32 

Aircraft Construction 34 

Aircraft Inspections 34 

Supersonic Transport 36 
Summary 36 


Aircraft Engine Requirements 38 

Aircraft Engine Types 39 

Aircraft Engine Parts 39 

The Four-Stroke Cycle Principle 40 

Engine Systems 42 

Fuel and Induction System 43 
Ignition System 44 
Accessories 44 

Power Factors 45 

Modern Powerplants 45 
Compressors 48 
Combustion Chambers 49 
Turbines 49 
Exhaust Cones 49 
Thrust Versus Power 49 
Turbojet, Turboprop, and 

Turbofan Engines 50 
Rocket Propulsion 50 
Atomic Propulsion 51 

Summary 51 


Pitot-Static Tube 52 

Venturi Tube 53 

The Airspeed Indicator 53 

The Altimeter 54 

Rote of Climb Indicator 55 

The Magnetic Compass 55 

Tachometers 56 

Magnetic Tachometer 56 
Electric Tachometer 57 

Oil Pressure Gage 57 

Oil Temperature Gage 57 

Turn and Bonk Indicator 58 

The Directional Gyro 59 

The Gyro Horizon 60 

Summary 61 


Airplane Attitude and Controls 62 
Controls 62 
Straight and Level Flight 62 

The Climb 63 

The Glide 63 

The Turn 64 

Use of Rudder in a Turn 65 

Overbanking Tendency 65 

Loss of Vertical Lift 65 

Rate of Turn 65 

Slipping and Skidding 65 
The Takeoff 67 
Landing Approach 67 
Sumnnary 69 

What Is Navigation? 71 
Forms of Air Navigation 71 
Position, Direction, and Distance 72 
Maps and Charts 74 
Plotting a Course 76 
V/ind Drift Correction 78 
Pilotage Navigation 79 
Dead Reckoning Navigation 79 
Radio Navigation 80 
Celestial Navigation 85 
Summary 85 

The Atmosphere 86 
Elements of Meterology 86 

Temperature 87 

Pressure 87 

Moisture 87 

Clouds 89 

Circulation 90 

Air Masses and Fronts 90 
Elements of V^eather Important in Aviation 91 

Ceiling 91 

Visibility 91 

Turbulence 92 

Icing 93 
V/eather Information Available to Pilots 94 

Hourly Sequence Reports 94 

Pilot Reports 94 

Maps 94 

Winds Aloft Reports 94 

Area Forecasts 96 

Terminal Forecasts 96 
Summary 96 


Air Terminal Problems 100 
Aircraft Communication 100 
Airport Traffic Control Tower 102 
A Typical Radio-Phone Conversation 103 
Air Traffic Service 105 
Flight Plans 106 

Typical Instrument Flight Procedure 108 
Summary 1 1 

Functions of the Federal Aviation Agency 1 12 
The Deputy Administrator 113 
Associate Administrators for Programs 

and for Development 1 1 3 
Associate Administrator for 
Administration 1 1 3 

Federal Aviation Regulations 1 1 4 

Pilot Regulations 1 15 

Air Traffic Rules 1 15 
Summary 1 1 7 

The Solar System 1 1 8 

Earth's Atmosphere 120 
The History of Rockets 121 
Current Space Problems 122 

Propulsion 122 

Guidance 1 23 

Orbits 125 

Atmosphere Re-entry 1 26 

Physical Problems 1 27 
Summary 1 29 

Quest for Knowledge 130 
Peaceful Uses 130 
National Security 131 
National Prestige 131 
Current Space Activities 131 

Explorer Satellites 131 

Pioneer Satellites 132 

Proiect Score 132 

Discoverer Satellites 132 

Transit Satellites 132 

Tiros Satellites 133 

Midas Satellites 133 

Echo Satellite 133 

Samos Satellites 133 
Lunar and Interplanetary Launchings 1 34 

Ranger Spacecraft 134 

Surveyor Spacecraft 1 34 

Mariner and Voyager Spacecraft 134 
Future Space Projects 135 

Meteorological Satellites 1 35 

Communications Satellites 135 

Observatory Satellites 135 
Man in Space 1 35 

X-15 Rocket Plane 135 

Project Mercury 1 36 

Project Gemini 1 38 

Project Apollo 139 
Peaceful Applications of Space Research 139 

Communications 1 39 

Weather 140 

Additional Research Benefits 140 

Summary 140 
NASA's Proposed 1964 Launch Program and Official 

World Records 142 


Government Regulations 1 1 2 



1 Average Annual Employment (1952-1963) 2 

2 Aerospace Manufacturing Industry Sales 
(1951-1962) 2 

3 Revenue Passengers Carried (1952-1963) 3 

4 Airline, Railroad, and Bus as Per Cent of 
Passenger-Mile Market (1950-1962) 4 

5 Hours Flown in General Aviation (1951-1962) 5 

6 A North Pole Centered Map 8 

7 The Wright Biplane in Flight Over the 
Sands of Kitty Hawk 13 

8 Air Movement Around a Wing 1 6 

9 Lift Increases as the Angle of Attack Is 
Increased 17 

10 Lift Must Exactly Equal the Weight of on 
Airplane 1 8 

11 Thrust Must Equal Drag 18 

12 Pitch, Yaw, and Roll 19 

13 Left Rudder Causes the Airplane to Rotate 
to the Left 20 

1 4 Lowering the Elevators Causes the Airplane 
to Nose Down 20 

15 Movement of the Control Stick to the Left 21 

16 Trim Tabs 21 

17 Airstream Action on the Rudder Trim Tab 21 

1 8 Side and Top Diagram of an Airplane 23 

19 Monoplane 24 

20 Biplane 24 

21 Various Wing Shapes 25 

22 Possible Wing Locations 25 

23 Internal Wing Construction 26 

24 Flaps in a Lowered Position 26 

25 Wing Slots Diagram 27 

26 Flying Boat 28 

27 Amphibian Airplane 28 

28 Welded Steel Tubular Fuselage 28 

29 Semi-Monocoque Fuselage 28 

30 Fixed Landing Gear 28 

31 Tricycle Landing Gear 28 

32 Landing Gear Being Retracted 29 

33 Principle of Oleo Strut Operation 30 

34 1. Fine or Low Pitch 31 

2. Coarse or High Pitch 31 

35 Full Feathering Propeller 31 

36 Propeller Pitch Performance Comparisons 31 

37 Feathered and Unfeathered Propeller 
Performance 31 

38 De-icer Boot Operation 32 

39 X-18 in Flight Tests 33 

40 Helicopter 33 

41 Aircraft Safetying Methods 34 

42 The Cockpit Section of the Link 707 
Simulator 35 

43 Aircraft Engine Cylinder Arrangements 38 

44 Types of Crankshafts 39 

45 Front View 9-Cylinder Radial Engine 39 

46 Cutaway View of Twin-Row Radial Engine 40 

47 Airplane Engine Cylinder Nomenclature 40 

48 Valve Operating Mechanism of a Radial 
Engine 41 

49 Stages of the Four-Stroke Cycle Engine 41 

50 Radial Engine Lubrication System 42 

51 A Typical Aircraft Fuel System 43 

52 Cutaway View of a Turbo Supercharger 44 

53 A Simplified Cutaway Drawing of a 
Spark Plug 44 

54 Schematic Diagram of an Aircraft Engine 
Magneto 44 

55 Typical Reciprocating Engine-Propeller 
Combination 45 

56 Reciprocating Engine-Propeller Combination 
Enclosed in a Tube 45 

57 Typical Turbojet Engine 46 

58 Simple Rocket Engine 46 

59 Schematic Diagram of a Ram Jet Engine 46 

60 Schematic Diagram of a Pulse Jet Engine 46 

61 Cutaway View of a Turbojet Engine 47 

62 Gas Generator Section of a Turbofan 
Engine 47 

63 Cutaway View of a Centrifugal Flow 
Compressor Engine 48 

64 Axial Flow Compressor of Turbojet 
Power LJnit 49 

65 Rocket Power Unit 50 

66 Standard Pitot-Static Tube 52 

67 Venturi Tube 53 

68 The Pitot-Static Tube Connections 53 

69 Altimeter 54 

70 Vertical Speed Indicator 55 

71 Magnetic Compass 55 

72 Magnetic Tachometer 56 

73 Electrical Tachometer 56 

74 Oil Pressure Gage 57 

75 Bourdon Tube 57 

76 Oil Temperature Gage 58 

77 Turn and Bank Indicator 58 

78 The Gyro Assembly 58 

79 Visual Indications of Various Turn and 
Bank Conditions 59 

80 Directional Gyro 59 

81 Gyro Horizon 60 

82 Controls, Control Cables, and Control 
Surfaces 63 

83 The Factors Affecting Attitude 64 

84 The Aerodynamic Functions of an 
Airplane Wing 65 

85 The Forces Acting on an Airplane in a 
Normal Turn 66 

86 Loss of Vertical Lift in a Turn 66 

87 A Skidding Turn 66 

88 Traffic Patterns 68 

89 An Imaginary Axis Through the Center of 
the Earth 72 

90 Lines of Longitude 72 

91 Lines of Latitude 72 

92 Latitude and Longitude Lines Correspond to 
Streets and Avenues 73 

93 Direction 73 

94 A Compass Rose 74 

95 Sectional Chart 75 

96 Standard Symbols Used on a Sectional 
Chart 76 

97 Method of Obtaining a Lambert Projection 77 

98 Measuring a True Course Line with 
Protractor 77 

99 Agonic and Isogenic Lines of Variation 78 

100 (left) Wind Drift 78 
(right) Wind Correction 78 

101 A Typical Wind Triangle 79 

102 Contact Flight Log 79 

103 Radio Facility Chart 80 

104 Radio Facility Legend 81 

105 Two-Way Radio System 82 

106 Directional Radio Transmissions 82 

107 Part of a Sectional Chart 83 

108 Automatic Direction Finder (ADF) 84 

109 Aircraft VHF Transmitter and Receiver 84 

110 The Atmospheric Regions 86 

1 1 1 Convective Wind Currents 87 

1 1 2 Principal Types of Clouds 88 

113 The Theoretical Winds on an Earth of Uniform 
and Even Surface 90 

114 Pilot's Forward Visibility in Snow Can Approach 
Zero 91 

115 Avoiding Convective Turbulence 92 

116 Surface Obstructions 92 

117 Turbulent Air 92 

118 Clear-Air Turbulence 92 

119 Three Stages in the Life Cycle of a 
Thunderstorm 93 

120 Rime Ice 93 

121 Key to Aviation Weather Report 94 

1 22 Sample Black and White Surface Weather 

Map 95 
1 23 Key to Report of Winds Aloft 96 

1 24 Area Aviation Forecast and Interpretation 97 

125 Terminal Forecasts and Interpretation 98 

126 Airport Control Tower 100 

127 Proper Way to Hold a Microphone 102 

128 Interior of an Airport Control Tower 103 
1 29 Airport Control Tower Operator 

Manning a Light Signal Gun 104 

130 Air Route Traffic Control Center 105 

131 Table of Organization of Air Traffic 
Service 1 06 

132 A Typical Flight Plan 107 

133 A Portion of a Radio Facility Chart 108 

134 Federal Aviation Agency Table of 
Organization 1 1 3 

1 35 Minimum Safe Altitudes for Aircraft 1 1 5 

136 Rights of Way 115 

137 Rights of Way for Aircraft in Flight 1 16 

138 Minimum Cloud Clearance Inside Control 
Area 1 1 6 

1 39 The Solar System 1 1 9 

140 Disc-Shaped Galaxies in the Southern 
Hemisphere 1 20 

141 Liquid and Solid Fuel Rocket Engines 123 

142 Conic Sections and Basic Orbits 125 

143 The Satellite Ellipse 125 

144 The Titan ICBM Is Launched from Cape 
Canaveral 128 

145 The NASA Mercury-Redstone III 131 

146 NASA's Satellite TIROS III 133 

147 Full-Scale Model of Surveyor Satellite 134 

148 Mercury Capsule 137 

149 Project Mercury, Ballistic Missile 138 

150 Mockup of a Project Gemini Spacecraft 139 

Table 1 Aerospace Industry Classification 1 
Table 2 Flying Times of Modern Jets vs. Douglas 
DC-7C 3 

Chapter 1 Living in the Aerospace Age 

No other mode of transportation has had greater im- 
pact on the world than aviation. None has so changed 
the economic, political, and social traditions of the 
world in such a short period of time. The phenomenal 
growth of the aerospace industry, the rapid expansion 
of commercial air travel, the tremendous influence of 
aviation on military concepts and international affairs, 
all have had inescapable and overwhelming effects on 
day-to-day living. 

The youth of today must have an appreciation and 
awareness of the history, practical effect, and future 
potential of this transportation giant. Only through 
an understanding and application of aeronautical 
principles, by both the present and future generations, 
will the United States be able to maintain its air- 
power position. Many young Americans have already 
realized the value of a technical aviation education, 
including flight and engineering, and are well on the 
way to participation in the Aerospace Age. Space 
travel and the space frontier are absorbing and vital 

But just as important is an awareness of the advan- 
tages and disadvantages, the privileges and restric- 
tions, and the rewards and consequences of expanding 
aviation in the world of today and tomorrow. The im- 
pacts of aviation are economic, social, and political. 

The Economic Aspect 

Aviation in the United States directly influences the 
economic activities of millions of individuals. Several 
hundred thousand persons are industrially employed 
in the field of aviation. Millions of passengers fly on 
the commercial airlines each year for both business 
and pleasure. Both the production and the distribution 
of goods and services are facilitated by the airplane. 
Mass-production firms use air freight when production 
line stoppages are threatened. Increasing quantities of 
goods are being flown direct from factory to retail 
outlets, providing more rapid delivery and eliminating 
the need for warehouses in a firm's distribution system. 

Air-mail letters move across the United States, non- 
stop, in approximately five hours. Even live lobsters 
are flown from Maine to air-conditioned supermarkets 
in Texas. The use of helicopters for air taxi and in- 
dustrial work is rapidly increasing. Businessmen are 
now aware of the economic value of owning and oper- 
ating private aircraft for business purposes. Corporate 
flying is growing in tremendous strides. As consumer 
incomes continue to grow, more and more people will 
own personal aircraft. 

Categorically speaking, there are three basic areas 
in aviation; (1) the aerospace manufacturing indus- 
try, both civil and military; (2) the air transport in- 
dustry; and (3) general aviation. 

Table 1. Aerospace Industry Classification 

Aerospace Manufacturing Industry; 

Aircraft Engines 
Aircraft Parts and Accessories 

Air Transport Industry; 

Domestic Scheduled Airlines 

Trunk Lines 

Local Service Lines 

Helicopter Airlines 

Supplemental Air Carriers 
International and Overseas Lines 
Alaskan Carriers 
Intra-Hawaiian Carriers 
All-cargo Airlines 

General Aviation; 

Business Flying 
Commercial Flying 
Instructional Flying 
Personal Flying 

The aerospace manufacturing industry includes all 
research, development, fabrication, assembly, and 
sales operations relating to airplanes, missiles, parts, 
accessories, and equipment. The industry also in- 
cludes major overhaul, maintenance, and modification 


63 (Fob.) 

Figure 1 — Averoge Annuol Employment in the Aircraft ond Parts Mfg. 
Industry (1952-1963). Source: Aerospoce Focfs ond Figures, 1963 
Edition, p. 69. 

In contrast, the air transport industry encompasses 
only scheduled flying activities performed by com- 
mercial airlines and air freight carriers. The routes 
flown, the rates charged for services, and all items 
pertaining to safety are carefully regulated by the 
federal government. 

General aviation consists of all other aviation activi- 
ties except those of the air transport industry and the 
military services. 


During World War II, the United States aircraft 
manufacturing industry became a large industrial 
complex capable of producing 100,000 planes per year. 
Employment soared to over 1.3 million persons. How- 
ever, after the war ended and enough civilian aircraft 
had been produced to satisfy the immediate post- 
war demand, the industry dropped to a point where 
it was producing at a rate of only 6 per cent of its 

Figure 2 — Aircraft Manufacturing Industry Soles (1951-1962). 

wartime capacity. With the onset of the Korean War, 
the industry began to expand again, and, since 1950, 
has grown to be one of the most important industries 
in the United States. In 1962, aircraft and allied 
manufacturing represented a $19.5 billion industry. 
(Figure 2.) This growth is economically significant 
because in ten years the industry created several hun- 
dred thousand new job openings— employment rose 
from 670,000 in 1952 to over 726,000 in 1963. ( Figure 

The foundation for this employment increase and 
growth of the industry is the national defense pro- 
gram. In recent years, over 50 per cent of the federal 
government's budget has been allocated to national 
defense; of this, a significant portion has been diverted 
to the aerospace manufacturing industry for research, 
development, and production work on airplanes, mis- 
siles, and spacecraft. During the 15-year period 1947- 
1961, 89 per cent of the total sales of 51 of the largest 
aerospace companies was to the federal government. 

Not only is a vast number of jobs created by the 
industry, but a wide variety of skills is also needed. 


Aircraft, missile, and spacecraft manufacturing all 
emphasize research and development activities. Be- 
cause there are constant changes in design and pro- 
duction methods, the research and development field 
is an important source of employment for engineers, 
scientists, technicians, and craftsmen. In 1956, the 
amount of money spent for researc?h and development 
in the aerospace industry exceeded that of all other 
industries. Since 1957 the industry has had a higher 
proportion of scientists and engineers involved in 
research and development work than has any other 
industry. In addition, these scientists have more 
craftsmen assisting them than is the case in any other 

Even though professional and technical personnel 
are necessary, there are also many job openings for 
skilled and semi-skilled production workers. Approxi- 
mately 50 per cent of the industry's working force are 
tool and die makers, sheet metal workers, machine 
tool operators, welders, inspectors, assembly line pro- 
duction workers, and maintenance men. 


October, 1958, marked the beginning of a new era 
in the history of commercial air transportation in the 
United States. During this month, a United States 
international carrier inaugurated the first regularly- 
scheduled commercial jet airliner service from New 
York City to Paris and soon after to London and Rome. 
Likewise, a major domestic airliner initiated non-stop 
transcontinental jet service in January, 1959. In Feb- 
ruary, jets began flying between Chicago and the West 
Coast with jet service soon following for all major 
cities in the United States. 

The development of commercial jet airliners repre- 
sents the highest degree of mechanical perfection yet 
achieved by man in the field of public transportation. 
The giant four-engine turbojet aircraft are capable of 
carrying 100 to 150 passengers, in silent, vibration-free 
flight, between 500 and 600 miles per hour, at altitudes 
of 40,000 feet, for distances up to 5,000 miles. 

The magnitude of progress in air transportation 
achieved since World War II becomes apparent when 
it is remembered that as late as 1941, air travelers 
were crossing the United States in two-engine, 21- 
passenger airliners at 165 miles per hour, requiring 
16 hours to make the trip. Even when comparing the 
jet with its predecessor, the highly-perfected, conven- 
tionally-powered DC-7C commercial airliner, the dif- 
ference is noticeable. On the average, the modern 
commercial jet airliners reduce flying time between 
cities by approximately 42 per cent. 




























57 58 




Figure 3 — Revenue Passenger Miles Flown (1952-1963). 
Aerospoce Facts and Figures, 1963 Edition, p. 126, and 
Week and Space Technology, Morch 16, 1964, p. 164. 


Table 2. Flying Times of Modem Jets vs. Douglas DC-7C 







New York to London 




New York to Paris 




New York to Rio de Janeiro 




San Francisco to Honolulu 




Los Angeles to New York 




New York to Los Angeles 




Economically speaking, since a jet transport can 
carry more people at higher speeds, it accomplishes 
more work in the same period of time than the con- 
ventional airliner. A jet transport carries twice as 
many passengers as a DC-7C at 1.5 times the speed; 
therefore, its productive capacity is three times that 
of the DC-7C. Another illustration of the economic 
importance of the jet airliner is the ability of one jet 



- ID 












r 35 



























Figure 4 — Airline, Railroad and Bus as Per Cent of Domestic Passenger 
Mile Market (1950-1962). Source: Aerospace Facts an6 Figures, 1963, 
p. 129. 

airliner to fly the North Atlantic route and carry the 
same number of passengers annually as a 40,000-ton 
ocean liner such as the Queen Mary. 

Three factors which indicate the economic value of 
air transportation are: (1) revenue passengers carried; 
(2) revenue passenger-miles flown; and (3) the dollar 
volume of sales revenue. Since 1949, the number of 
revenue passengers carried by both domestic and 
international airlines has more than quadrupled. In 
1949, the domestic airlines carried over 12 million 
revenue passengers. In 1962, over 62 million were 
flown. Similarly, international airlines increased from 
1.5 million revenue passengers flown in 1949 to over 
seven million in 1963. 

During this same period, revenue passenger-miles 
flown by the domestic trunk carriers quintupled, 
while the international carriers quadrupled their mile- 
age. In 1962, the domestic trunk airlines flew nearly 
44 billion passenger-miles and in 1963 the international 
carriers flew 13.3 billion passenger-miles. The total 

revenue passenger-miles flown by these two carriers 
is equivalent to ten persons each making 10,396 round 
trips to the moon during a single year, or more than 
28 round trips each day. 

In 1962, sales revenue in the air transport industry 
climbed to a volume of $3.4 billion. 

In 1938, the airlines accounted for only 1.7 per cent 
of the total passenger volume, while railroads received 
65.5 per cent, and buses 32.8 per cent, but twenty- 
five years later, air travel had increased about 25 
times, while rail travel had declined over 51 per cent 
in relative importance. By 1962, the domestic airlines 
received 45 per cent of the total passenger volume; 
railroads, 26 per cent; and buses, 29 per cent. ( Figure 

The demand for scheduled airline passenger service 
in the U. S. domestic market is projected to rise from 
about 36 billion revenue passenger-miles in 1962 to 
43 billion in 1965 and to 57 billion in 1970. The trip- 
length distribution of this demand is expected to 
shift modestly toward the long haul. The coach- 
economy share of this demand is projected to increase 
markedly, from more than 55 per cent in 1962 to about 
85 per cent by 1970. The development of new all- 
cargo aircraft and new cargo-handling systems, to- 
gether with more efficient carrier operating practices 
and keener competitive situations, should enable 
domestic aircargo prices to drop about 45 per cent 
during the 1960's. This factor, plus the projected 
expansion of the gross national product and the in- 
creased demand for airmail which seems likely, is 
expected to stimulate a combined demand increasing 
from about 510 million ton-miles in 1963 to about 
2'/3 billion ton-miles in 1970. 

The free world demand for international air pas- 
senger transportation is projected to rise from about 
26 billion revenue passenger-miles in 1960 to 38 billion 
in 1965 and 54 billion in 1970. The U. S. flag car- 
riers' revenue passenger-miles are projected to in- 
crease from 8'/, billion in 1960 to 13.3 billion in 1963 
and to about 17 billion in 1970. The coach-economy 
share of this demand is projected to increase from 
an already high share of about 75 per cent in 1960 
to 90 per cent by 1965 and to 94 per cent by 1970. 
Predicated on the forecast that rates in the free world 
international aircargo market will be reduced by 60 
per cent between 1960 and 1970, the free world effec- 
tive demand for international aircargo and airmail 
transportation is projected to increase to more than 5 
billion ton-miles in 1970. The U. S. flag carriers' share 
of this demand is projected to increase from about 1.8 
billion ton-miles in 1963 to about 2 billion ton-miles 
in 1970. 

Considering the fact that only 30 per cent of the 

people in the United States have ever flown, the above 
estimates do not seem unreasonable. A vast market 
of potential air travelers is still available and, further, 
a growing population indicates that the market poten- 
tial is expanding, not contracting. 

In summary, the economic effects of the present air 
transport industry are: (1) a sharp shrinkage of 
distance in terms of time; (2) a greatly expanded 
transport capacity of the new jet in comparison to 
propeller-driven aircraft; (3) a tremendous increase 
in the number of people using air transportation for 
business and pleasure; and (4) a major shifting of 
traffic volume from the railroads to the airlines. 

What economic significance will the air transport 
industry have on employment? In 1963, about 175,000 
persons were employed in this industry, and more 
than 40,500 worked for the Federal Aviation Agency. 
In 1952, the industry employed about 98,000 people. 
Therefore, non-governmental employment increased 
about 70 per cent in an eight-year period. 

Airline operations require many skilled workers to 
fly and maintain aircraft, provide passenger and ter- 
minal service, and perform long-range planning for 
management purposes. Pilots, navigators, flight engi- 
neers, mechanics, traffic agents, dispatchers, meteor- 
ologists, engineers, and administrators, all combine 
their talents to provide a properly functioning, efficient 
airline. In addition. Federal Aviation Agency person- 
nel are concerned with air traffic control, airways 
communications and navigational facilities, flying 
safety, and research and development activities. A 
very important and growing field within the FAA is 
the development of the air route traffic control system 
which will create new positions for radar controllers, 
technicians, and dispatchers. 

Of the people working for an airline, about 14 per 
cent are flight personnel, 20 per cent are mechanics, 
and 2 per cent are communications specialists. The 
remaining 64 per cent are concerned with ticket sales, 
reservations control, ground servicing of aircraft, sales 
management, personnel administration, economic re- 
search, legal counsel, and executive duties. 

Air Cargo 

The aircargo business is conducted by two groups: 
( 1 ) the all-cargo airlines, and ( 2 ) the regular domes- 
tic and international airlines. The all-cargo airlines 
were established to carry aircargo exclusively. 

The volume of aircargo— freight, mail, and express 
—has been increasing over the years. In 1962 the 
total volume of cargo carried by the certificated air- 
lines totaled nearly 1.3 billion ton miles of which 
898.1 million ton-miles was freight, over 251.4 million 
ton-miles was mail, and 70 million ton-miles was 







' 1 1 1 ._^ 








1 1 






^A — UA — 



51 5? 53 54 55 56 57 58 59 60 61 62 

Figure 5 — Hours Flown in General Aviation (1951-1962). Source: 
Aerospoce Focfs ond Figures, 1963 Edition, pp. 133-4. 

express. While the percentage of volume of cargo 
carried by air is less than one per cent of the total 
intercity ton-miles moved by all forms of transporta- 
tion, the airlines are planning on carrying much 
greater quantities in the future. 

Air transportation costs still are high when com- 
pared solely with the costs per mile of water, rail, or 
truck transport. Today, however, by carefully analyz- 
ing total distribution costs, the airlines are often able 
to show manufacturers that standard production-line 
items may be shipped more profitably by air. Savings 
result primarily from the ability of the manufacturer 
to eliminate large inventories, cut warehousing re- 
quirements, and reduce the number of times the prod- 
uct must be handled. Moreover, good will is estab- 
lished between the manufacturer and his customer 
through rapid attention to and delivery of the cus- 
tomer's orders. 


The helicopter is a relatively uneconomical form of 
transportation. It requires several hours of ground 


maintenance time for every hour of flight time. It is 
slow and difficult to fly. Only now is it beginning to 
achieve all-weather operation. Further, its payload is 
limited when compared to that of an airplane. Yet 
the helicopter fulfills a very important need in com- 
mercial air transportation because of its small-field 

Scheduled helicopter airlines carry passengers be- 
tween downtown locations and airport terminals. In 
1959, three cities had scheduled helicopter service- 
New York, Chicago, and Los Angeles. A St. Louis 
firm has inaugurated metered helicopter service 
similar to that provided by taxicabs. Even though heli- 
copter transportation is still in its infancy, its growth 
record is phenomenal. Operations began in 1953. 
During that year 1,000 passengers were carried. In 
1962, 359,000 passengers were carried-a 359-fold in- 


The major divisions of flying within the general 
aviation classification are (1) business, (2) commer- 
cial, including agricultural and charter flying, (3) 
instructional, and (4) personal. In terms of number 
of aircraft operated and number of hours flown an- 
nually, general aviation leads all other segments of 
civil aviation. In 1962, over 82,000 aircraft were 
engaged in general aviation flying. This contrasts 
with approximately 2,200 commercial airliners in 
domestic use. Moreover, these 82,000 airplanes flew 
an estimated 13.3 million hours that year, over three 
times the number of hours flown by the commercial 

After World War II many people thought the air- 
plane would become as commonplace as the auto- 
mobile, with millions owning and operating small, 
personal aircraft. Flight training was stimulated by 
federal government educational benefits granted to 
veterans. Enrollment in flight schools soared. In 1947, 
general aviation reached its all-time high in number 
of hours flown. This 1947 record of 16.3 million hours 
quickly dropped to an average level of 8.9 million 
hours during the period 1950-1955. (Figure 5.) Lim- 
ited utility and high operating and ownership costs 
of aircraft proved detrimental to the widespread 
growth of private flying. 

Since 1946, however, an important trend has materi- 
alized. Businessmen have discovered that the airplane 
is a valuable tool in the operation of their enterprises. 
The total hours flown for business purposes increased 
from 2.6 million hours in 1949 to 5.5 million hours 
in 1962. In eleven years, the increase was two-fold 
and accounted for over 40 per cent of the total num- 
ber of hours flown in general aviation in 1962. 

The use of business aircraft permits a company to 
expand its sales volume by increasing its market cov- 
erage without necessarily increasing the number of 
salesmen on its staff. For example, a 200-mph com- 
pany plane can fly from Dallas to Houston in one hour 
and 12 minutes; from New York to Boston in 55 min- 
utes; from Los Angeles to San Francisco in one hour 
and 42 minutes. The advantages of covering a regional 
sales territory by aircraft instead of by automobile 
are obvious. 

General aviation aircraft also have many uses in 
addition to that of transportation. Farmers, ranchers, 
and others engaged in agriculture have found the air- 
plane valuable for aerial application of chemicals or 
seed to land, crops, and forests. Control of insect inva- 
sion is a most important aspect of this work. 

Chartered passenger and cargo transportation is a 
significant part of general aviation. Commercial flying 
accounts for about 18 per cent of the total number 
of hours flown in general aviation activities. Included 
in this category are pipeline control, forestry patrol, 
mapping, aerial photography, mineral prospecting, 
and advertising, as well as agricultural flying. 

Instructional flying, including dual and solo flight, 
is responsible for about 15 per cent of general aviation 
flying. Immediately following World War 11 instruc- 
tional flying accounted for over 60 per cent of general 
aviation activity. As veterans' benefits diminshed, in- 
struction also diminished, so that it soon represented 
the smallest portion of general aviation annual flying 
hours. Since 1955, this trend has reversed sharply, 
with instructional flying increasing from 1.3 million 
hours in 1955 to 1.9 million hours in 1962— an increase 
of 49 per cent. With the ever-increasing popularity of 
the airplane in business flying, the present increase in 
flight training promises to continue. 

Personal flying tends to remain a fairly constant 
percentage (approximately 27 per cent) of the total 
hours flown in general aviation. The level of consumer 
income is a determining factor in the number of hours 
of pleasure flying. 

It is estimated that the current value of the general 
aviation fleet exceeds $700 million. Add to this a $500 
million per year sales volume of fixed-base operators 
serving over 200,000 active pilots, and it is evident 
that general aviation now has a firm foundation in the 
economy. In view of the great potential for increased 
business flying, this segment of aviation is expected 
to experience remarkable growth during the next 

The Social Aspect 

In order to judge comprehensively aviation's effect 
on the "social man," it is necessary to review certain 


aspects of everyday life and determine how the air- mathematics of missiles and rockets, astronomy, ceies- 
plane has contributed to a re-appraisal, if not a re- tial navigation and geography, and flight engineering 
evaluation, of social concepts. development. 


Any important means of transportation moves popu- 
lations. Ships brought people to America; the railroads 
stimulated the growth of cities; the automobile dis- 
persed city people outward and drew rural inhabitants 
in toward the outskirts of the cities. 

Aviation has a similar significance in the distribution 
of population. The out-of-the-way locality, where min- 
erals, chemicals, and other natural resources may be 
exploited, can be brought into contact with other 
population centers by the speed of air transportation. 
Similarly, the sparsely populated regions lying adja- 
cent to or on air routes, between densely populated 
centers, will tend to increase in population. 

A closely related factor to future population distri- 
bution is the ability of the airplane to promote new 
business and trade activities in areas not now served 
by railroads or highways, but which, though undevel- 
oped, are potentially rich in resources. The 49th state, 
Alaska, is an excellent example of a potential popula- 
tion growth area. 


In an over-all sense, the influence of aviation on 
education is synonymous with its influence upon civi- 
lization and culture. Speaking of education in a 
narrower sense, i.e., a formal classroom-laboratory, 
teaching-learning process, aviation has had a tremen- 
dous impact on elementaiy, secondary, and university 

Recently, a survey was completed which indicated 
that 47 institutions of higher learning conferred de- 
grees in aeronautical engineering on the basis of a 
four-year curriculum; 22 others conferred such degrees 
on the basis of a five-year curriculum; while 25 schools 
offered a program of studies in either aeronautical 
administration or other aviation service fields. 

Aviation trade schools have been established in 
every state. There are 69 airframe and aircraft power- 
plant mechanics schools. Of the 843 flight schools, 
216 teach flight and related subjects, and the other 
627 teach flight only. In addition, many airlines, air- 
craft assembly factories, and aircraft engine plants 
maintain schools or apprentice training programs. 

The social sciences not only tell the history of pow- 
ered flight, but also relate its social, economic, and 
political effects. The physical sciences include the 
theory of the airfoil, the physics of airframe con- 
struction, the chemistry of fuel and metals, the 


The habits and living conditions of the family have 
also been affected by the introduction of the airplane. 
The most noticeable change has occurred in the 
family's choice of vacation sites. Within the usual 
two-week vacation period, it is now possible to visit 
scenic and historic locations which are thousands of 
miles away. Relatives who have moved to distant 
places are only hours away. Because of this, there has 
been a tendency for family members to feel a greater 
freedom of choice in choosing to relocate without 
necessarily weakening family ties. 

Eating habits have been changed by the increased 
use of aircargo facilities. Foods from distant areas are 
now more readily available. New products are quickly 
distributed to the consumer and new markets created 
and expanded. 

Widespread influence of privately-owned aircraft 
on family hfe is contingent upon the further devel- 
opment of low-cost, high-efiiciency, light airplanes. 
Privately-owned aircraft will provide a higher de- 
gree of personal mobility and influence sports activ- 
ities—specifically camping, hunting, and fishing— of 
families in higher income brackets. Big spectacle 
sporting events can be more easily attended, and 
increased sporting activity in more widely separated 
areas is possible. 

The Political Aspect 

Just as aviation has a social and economic impact 
upon persons and nations so, too, it has an effect in 
the realm of politics. In the fields of total air power, 
military strength, and international relations, the im- 
pact of aviation is noticeable. 


World War I indicated to military strategists that 
fundamental changes would be required in planning 
offensive-defensive actions in all wars. At first planes 
were employed only as mobile observation posts which 
could quickly and accurately report concentrations of 
enemy troops and fire power. As this activity in- 
creased, the next logical step to occur was an attempt 
to deny this activity to the opposition. Airplanes not 
only carried a pilot or a pilot and observer, but also a 
rifle and hand grenades. Soon, machine guns were 
mounted on the nose of the plane, and later bombs 
were also carried. During World War I, a new aviation 
jargon came into being and new tactics were evolved. 


but the full potential of aerial warfare was neither 
understood nor employed. 

In the period between the two great wars, some 
nations did more to incorporate aviation into their 
military forces than did others. There was, however, 
a general lack of comprehension of the support, recon- 
naissance, fighter, bombing, and transport abilities of 
a modern air force. Although the first powered flight 
occurred in the United States in 1903, this country 
was one of the last major powers to become fully 
aware of the significance of the airplane. 

The most famous of the early advocates of aviation, 
particularly in the military field, was General "Billy" 
Mitchell. He proved the superiority of the airplane 
over the battleship, but his strategical victory ended 
in his personal defeat. He was court-martialed and 
resigned from the Army, although he continued his 
fight for the recognition of a strong military air fleet. 
Today, the United States has implemented many of 
the ideas which General Mitchell attempted to pro- 
mulgate in the 1920's. 

During World War O, the aviation industry "grew 
up," commercial air transportation was vastly ex- 
panded, and military commanders not only recognized 
the value of an air force, but assigned to it an equal 
area of responsibility with the Army and Navy. The 
importance of this partnership role of the Air Force 
was confirmed when the Congress decreed in 1947 
that a new Cabinet-level post should be created, i.e., 
the Department of Defense, in which the Army, Navy, 
and Air Force had equal status. 

Since World War II, the greatest demonstration of 
the use to which air power could be put was given 

Figure 6 — A North Pole-Centered mop, or a polar projection, 
the new world geographic relationships created by the airplane 

during the "Berlin Airlift." Thousands of tons of food, 
clothing, coal, and other necessities of life were air- 
lifted into beleaguered Berlin. This accomplishment 
was carried out without the loss of a life or the loss 
of an aircraft and was completed during all kinds of 
weather and on a 24-hour schedule. 

Air power today includes the military air force, 
commercial air transportation, the aircraft indus- 
try, and general aviation. It is not the size of the 
fleet of military aircraft alone which detennines air 


Until the beginning of World War II, it had been 
the American tradition to be isolationist— to "go it 
alone"— to avoid being involved in "foreign entangle- 
ments." Only a terrifying event, such as the bombing 
of Pearl Harbor, could change the thinking of the 
public for any length of time. There was, of course, 
a more liberal trend of thought— one which reflected 
a strong tie with Europe. This feeling of internation- 
alism was, for the most part, concentrated on the 
Atlantic Coast. This was logical, of course, because 
New York was closer to London, Paris, Rome, and 
Berlin than was Chicago. 

It has only been since the end of World War II 
that many midwesterners and westerners discovered 
that they had been looking at the wrong map. The 
well-known Mercator Map did not give an accurate 
picture. The Polar Map clearly pointed out that the 
distances from Europe to Chicago, Denver, and 
Seattle were approximately the same as the distance 
from New York to these same places in Europe. ( Fig- 
ure 6.) 

Commercial airlines, in 1957, began flying the Polar 
route over the top of the world, and doing it on sched- 
ule and at a high rate of speed. If the commercial 
planes could pioneer these routes and accept them as 
safe flying areas, speedy enemy bombers could do the 
same. Our military defense conception had to be 
revised when this most disturbing fact was finally 
acknowledged. The heart of the United States, in a 
third world war, could easily become a battleground. 
The long-distance, two-ocean defense system became 
obsolete. The airplane forced tlie American public to 
re-appraise and re-evaluate America's vulnerability 
and its traditional concepts concerning international 

In today's Aerospace Age, international affairs have 
become a dynamic force. Diplomacy and international 
relations are intelligently discussed by the average 
citizen. Although much of the credit can be given to 
the progress and enlargement of the communications 
system of the world, a part of this awareness of world 


events can be attributed to the rapid advances in 
commercial and private flying. It is no longer consid- 
ered unusual when a high official of government or 
industry travels to another country or continent for 
a conference and is back at his desk in a day or so. 
Where it formerly took days or even weeks for com- 
plete films of a great event in Europe to arrive and 
be distributed throughout the nation, today, by com- 
bining the airplane and the television set, the Ameri- 
can public can see a coronation or an historical event 
in less than ten hours after the event takes place. Or, 
again through the medium of television, they may 
view the actual firing of a missile from Cape Canav- 
eral, which, in itself, is a tribute to the importance of 
air power and already has influenced international 


Another indication of aviation's importance may be 
noted in the use of airplanes by government officials, 
chiefly the President of the United States. The Office 
of the President has on call a small fleet which, in 
addition to jet aircraft, also contains helicopters. 

It is notable that political campaigning methods 
have also changed during the past twenty years. It is 
no longer necessary for a candidate to spend much 
time away from his headquarters or to plan a cross- 
country trip where his speeches have to be given 
in geographic pro.ximity. In future campaigns, a can- 
didate may appear before an audience in Chicago 
on one day, in Dallas the next, in New York on the 
following day, and then in Los Angeles the day after 
that. Political leaders have become mobile and this 
factor has permitted and encouraged greater appreci- 
ation and understanding of American politics by a 
larger number of voters. 


Today aviation exerts considerable influence upon 
the economic activities of mankind. The aerospace in- 
dustry provides thousands of job opportimities. It has 
grown to be a dominant employer in manufacturing. 
Further, this industry consumes a sizeable portion 
of the total defense budget, which is sustained by 
all taxpayers in this country. 


Commercial aviation is entering a new era, with 
ever-widening horizons. The commercial jet airliner 
promises to revolutionize the travel habits of business- 
men and families alike. The distances of global travel 
have been reduced to a few hours of pleasant riding 
in air-conditioned, living-room comfort. 

General aviation is coming into its own with the 
growing use of aircraft for business travel. Increasing 
acceptance of the airplane as an economic business 
asset will acquaint new thousands with private air 
travel. As consumer incomes increase, light aircraft 
ownership costs will fall within the reach of hundreds 
more. Freedom of movement, now associated with 
the automobile, may be shifted to the airplane. 

Sociological change has followed the development 
of the airplane. The airplane has increased the living 
tempo, opened new markets, and affected the distri- 
bution of the world's population. Distant and previ- 
ously inaccessible areas will be opened, new towns 
will be constructed, and sparsely populated regions 
lying adjacent to air routes will increase in population. 

Formal education will be vitally affected by avia- 
tion with all phases of the present educational system 
directly influenced by aviation activity. Family life 
has also been changed, principally in its choice of 
vacation sites and in the dispersion of family members 
to different geographical areas. Some variation has 
been noted in eating habits since speedy transporta- 
tion makes perishable products more easily available. 

Politically, the airplane has changed military con- 
cepts. Today the United States Air Force has equal 
status with the Army and Navy. In international af- 
fairs, the airplane has forced the American public to 
re-evaluate its role in diplomatic relations. Now that 
the Polar route is being flown daily, the midwestern 
and west coast cities are as close to the capitals of 
Europe and Asia as are the cities on the east coast. 
Domestic political campaigns have been re-appraised 
in order to take advantage of airplane mobility. Politi- 
cal leaders can now cover more territory and speak to 
more citizens during a campaign than has ever before 
been possible. 

Aviation in all of its varied facets represents a dy- 
namic force in a growing world. The changes it has 
brought and will continue to bring represent a never- 
ending challenge to the youth of today. 

1. How has aviation aided in the redistribution of 
the world's population? 

2. What are the three factors used to indicate the 
economic value of air transportation? 

3. The helicopter is useful for many tasks. To what 
use is it particularly well suited? 

4. What did World War I indicate to military strate- 
gists with respect to military aviation? 


5. Who was "Billy" Mitchell and what has been his 
contribution to the Aerospace Age? 

6. List the tv'pes of jobs required to operate an air- 

7. When was the Air Force officially created as a 
separate service? 

8. In what way has American family life been af- 
fected by the airplane? 

9. What are the five classifications into which the 
aerospace industry is generally divided? 

10. State why it is important for modern youth to 
understand the nature and various aspects of 
aerospace activities. 

11. What does the definition of air power include? 

12. About what per cent of the people in the United 

States have flown in an airplane? 

13. Relate the various ways in which aerospace in the 
United States directly influences the economic 
activities of individuals. 

14. What is the most important segment of general 
aviation? Discuss the reasons for its growing 

15. Compare the performance capability of a new 
commercial jet airliner with that of a convention- 
ally-powered commercial airliner. 

16. What is the economic significance of the growth 
in aerospace manufacturing since 1947? 

17. Why has the ability to navigate the Polar route 
safely caused a change in United States military 
defense planning? 

Chapter 2 History of Flight 

Since the beginning of recorded history, there have 
been evidences in the drawings and folklore of all 
peoples that man has always wanted to fly— that he 
longed for wings. Even the earliest of prehistoric men, 
to whom the invention of the stone ax was a develop- 
ment of great importance, must have gazed upward 
and, like his descendants for thousands of years, en- 
vied the freedom of birds and their ability to sail 
gracefully far up into the sky. 

The first expressions of man's desire to fly, and his 
first realizations of his utter inability and helplessness, 
are to be found in early legends and mythologies. 
Man, being unable to soar up into the heavens, 
endowed his gods with the ability to fly. 

Everyone is familiar with the Greek messenger god, 
Hermes, and his winged sandals; the German Val- 
kyrie who descended from the abode of the gods to 
battlefields on earth and carried back with them to 
Valhalla the slain heroes; the legend of Bellerophon; 
the wonderful winged horse Pegasus; and countless 
other stories. 

The first concrete evidence of man's attempt to con- 
struct a flying machine occurred about 400 B.C. 
Archytas, a Greek philosopher and disciple of Pythag- 
oras, became interested in flying and allegedly con- 
structed a wooden pigeon. According to scanty rec- 
ords now available, the bird flew, but details of its 
construction and source of power were not recorded. 

Undoubtedly there were other attempts to fly by 
men in later centuries, but the first man to work out 
plans intelligently for flying devices was the master 
artist Leonardo da Vinci. About the time of Christo- 
pher Columbus, da Vinci developed a toy helicopter 
by constructing small pinwheels out of paper. He also 
spent considerable time in designing flying machines 
patterned after bodies of birds. These machines had 
flapping wings which moved when the flyer pumped 
his arms and legs up and down. Although he built 
machines from his plans, needless to say da Vinci's 
physical strength could not develop sufficient power 
to raise himself from the ground. Had there existed 

at that time a practical engine, an airplane would 
probably have been flown successfully centuries be- 
fore the Wright brothers made their flight. 

Other drawings executed by da Vinci included the 
plan for the first propeller and the first parachute. As 
a result of his careful observations of birds, he became 
the first proponent of modern streamlining. 

Balloons and Gliders 

In many countries and for many years men contin- 
ued their search for the secrets of flying. These early 
experimenters studied the physical stnictiu-e of birds' 
wings and from this research attempted to construct 
man-carrying wings. These efforts to develop omi- 
thopters were singularly unsuccessful. 

Sir George Cayley (1773-1857), a distinguished 
British scientist, scoffed at the flapping-wing idea. 
It was his belief that a machine with a fi.xed wing or 
wings was the solution to flight and that the machine 
should have mechanical power to drive it through 
the air. 

During the latter part of the 17th century and the 
early years of the 18th century it was in France that 
the greatest amount of research and experimentation 
was done. In 1678, Besnier built a pair of wooden 
wings covered with fabric. With these hand-made con- 
trivances, he glided successfully, at first from low 
hills, and finally from the highest window in his house 
to the ground below. To him goes the honor of being 
the first successful glider pilot. 

Handicapped as the early pioneers were by lack of 
power and suitable materials for their experiments, 
it is not surprising that man first left the earth in a 
balloon, not in an airplane. The discovery in 1766 of 
a very light gas called hydrogen, and the observation, 
by two French paper mill owners, the Montgolfier 
Brothers, that warmed air rises, was responsible for 
the early experiments in 1783. 

Following the wave of enthusiasm and interest 
which developed after the successful balloon flight 


of the Montgolfiers, many men conducted other bal- 
loon flights. The major problem these men attempted 
to solve was that of finding a method to control the 
direction of a balloon flight. 

The first flight by a dirigible balloon or airship is 
attributed to Henri Giffard. He constructed a light- 
weight steam engine of about 3 hp and fitted it to 
his airship, which had an envelope with pointed ends, 
thus establishing the cigar shape which was to be 
characteristic of airships throughout their period of 
development. On September 24, 1852, this airship 
made a flight of 17 miles, starting from the Hippo- 
drome in Paris and landing near Trappes. 

France continued to lead in the development of the 
airship for another hundred years, though inventors 
in Italy, Great Britain, and Germany were making 
some contributions to its development. One of the 
most colorful personalities among the experimenters 
was Santos-Dumont, a Brazilian living in France. Be- 
tween 1897 and 1904 he built and flew 14 airships. 

During this period the first known rigid airship was 
built by an Austrian, David Schwartz, in Berlin. It 
made a flight but did not live up to expectations. The 
work of Schwartz was probably most important be- 
cause it influenced Gount Ferdinand von Zeppelin, 
a retired German army officer, to begin work on 
dirigible airships. 

Zeppelin was a fine engineer and his work with 
dirigibles was so outstanding that airships are often 
called Zeppelins. The first airship built by Zeppelin 
was launched on July 2, 1900, at Lake Constance, Ger- 
many. It had a capacity of about 350,000 cubic feet 
of hydrogen, a cigar-shaped aluminum girder frame, 
and was propelled by two benzine engines each driv- 
ing two four-bladed propellers. The outer cover was 
of linen. It was called the LZ-1 and was nearly 420 
feet in length and 38 feet in diameter. This first rigid 
airship made three successful flights but its further 
development was abandoned thereafter because of 
lack of money. 

Of all the early pioneers, the man whose work was 
most helpful to the Wright Brothers was Sir George 
Gayley. As a lad, Cayley was in the crowd that wit- 
nessed the balloon flights of de Rozier, who was the 
first man to fly in the Montgolfier balloon. Cayley 
first experimented with paper helicopters, flapping- 
wing gliders, and finally a rigid, fixed-wing glider. 
He at first flew the glider by running downhill with it 
suspended over his head. Later, he discovered that, 
with modifications, the wing had sufficient lifting 
power to sustain his weight. Continued experiments 
led him to adopt a double-wing glider or biplane. 
He also tried to design and construct a light engine 
which would permit his glider biplane to take off 

under its own power. However, due to the lack of 
materials which were both light and strong, he failed. 
Nevertheless, he had made a lasting contribution to 
the science of aeronautics. 

Generally speaking, the era of haphazard experi- 
mentation was over by the middle of the 19th century. 
Through careful research, the outstanding pioneers 
who followed Cayley developed more effective wing 
shapes, methods of balance and control, and, ex- 
tremely important, they made thousands of test flights. 
These men include the Frenchman Octave Ghanute, 
the German Otto Lilienthal, Professor John J. Mont- 
gomery (the first American to achieve success), and 
Professor Samuel P. Langley. 

Professor Langley, a scientist associated with the 
Smithsonian Institution, designed and built a few suc- 
cessful models but was destined never to achieve the 
distinction of being the first man to pilot an airplane. 
His designs were exceptionally good. Professor Lang- 
ley's largest and last airplane crashed after taking off 
from a houseboat on the Potomac River shortly 
before the flight at Kitty Hawk. It is interesting 
to note that quite a few years later a machine was 
constructed following his original design and, with 
only a few minor modifications, was successfully flown 
by Glenn H. Curtiss. 

Experiments of the Wright Brothers 

The Wright brothers operated a small bicycle shop 
in Dayton, Ohio. Like most American boys, they had 
built and flown many kites. Their interest in airplanes, 
however, became seriously aroused after reading of 
the experiments and flights of Octave Ghanute and 
Otto Lilienthal and the experiments of Professor 

They collected as much data as was then available 
and began their experiments by copying the various 
types of wings that had been developed and by test- 
ing those wings under a wide variety of conditions. 
They found that both Langley and Lilienthal had been 
correct in many of their theories, but, by further ex- 
perimentation, they were successful in discovering 
new facts concerning the airplane wing. They also de- 
veloped a small wind tunnel in which they tested hun- 
dreds of variously-shaped wings and made careful 
note of the performance characteristics in each case. 

Their scientific approach to the problem of flight 
was destined to bring them success. On the basis of 
their experimentations Wilbur and Orville Wright 
designed and built a glider, which, when tested at 
Kitty Hawk in 1902, was by far the most satisfactory 
glider yet built. They made over one thousand flights, 
some of which ranged between five hundred and a 


thousand feet— an unheard of distance at that time. 

During this period the Wrights also designed, under 
necessity, a satisfactory rudder— the forerunner of our 
modern aileron, a control which banks the airplane 
to the left or right. To accomplish this the pilot actu- 
ally bent or warped the trailing edge of each wing 
as necessary, thus enabling the glider to fly "straight 
and level." The basic method of moving the controls, 
developed by the Wrights in 1902, is practically the 
same as that in use today. 

After bringing the glider to a high state of perfec- 
tion, the Wrights next turned their attention to power. 
After searching widely among all types of gasoline 
and steam engines, they reluctantly came to the con- 
clusion that no suitable engine existed. All of the types 
studied were either too heavy or lacked sufficient 
power. It was typical of these men that, faced with 
such a difficulty, they did not give up their dreams 
but sat down and painstakingly designed and built a 
light yet fairly powerful engine. 

Still another handicap awaited them. No one could 
give them any valuable information on propellers. 
Although steamboats had been using water propellers 
for quite a long time, little work and practically no 
thought had been expended on propeller design. Thus 
they were further delayed by the necessity of design- 
ing, testing, and constructing many models of pro- 
pellers, emerging in the summer of 1903 with two suc- 
cessful designs. Finally, all was in readiness. 

Man's First Flight 

On a cold, blustery morning, the 17th of December, 
1903, man's dream for centuries was realized. Just 
after half past ten, Orville Wright took the pilot's 
position, a prone arrangement developed during their 
glider experiments. Wilbur stood at the wing tip to 
steady the machine as it moved along the rail. The 
engine was warmed up for two or three minutes, and 
then the aircraft moved along a launching rail and 
took off, to remain in the air for 12 seconds, when it 

Figure 7 — The Wright Biplane in Flight oyer the Sands of Kitty Hawk. 

darted to the ground. Its forward speed was 7 mph. 
There were only five people to witness this event, but 
fortunately the first flight was recorded by one photo- 
graph, which has been reproduced hundreds of thou- 
sands of times and seen by millions of people since 
that day. (Figure 7.) 

Later Developments 

After the initial success of the Wright brothers, 
improvements in airplane and engine design came 
swiftly. Longer flights at greater speeds and higher 
altitudes succeeded each other with amazing rapidity. 
Louis Bleriot, a Frenchman, crossed the English Chan- 
nel in 1909. C. K. Hamilton flew from New York to 
Philadelphia and back again in 1910. It was not until 
World War I, however, that large-scale development 
and construction of the airplane took place. For the 
first time, governments of the world spent consider- 
able money and time to improve airplanes for recon- 
naissance, fighter, and bomber puqjoses. 

At the end of the war, private flying expanded. Gov- 
ernment surplus planes were sold to former military 
pilots. These aircraft, soon appearing wherever there 
were open grassy fields, introduced the miracle of 
flying to thousands of people. The search for improved 
design and construction of engines and airframes con- 
tinued. Better materials and safer methods of construc- 
tion were discovered. More powerful engines were 
built to assist man in his efforts to conquer space. 

In 1919, the Atlantic Ocean was spanned by United 
States Navy airmen in a Curtiss flying boat, the NC-4. 
In 1922, General "Billy" Mitchell flew a Curtiss "Racer" 
at 222.9 mph to hold the world's speed record. Mem- 
bers of the United States Army Air Service flew 
around the World in 1924. In 1926, Commander Rich- 
ard E. Byrd and Floyd Bennett flew over the North 
Pole. Charles Lindbergh and The Spirit of St. Louis 
made the first non-stop flight from New York to Paris 
in 1927. Byrd and Balchen flew over the South Pole 
in 1929. Speed over distances occupied the attention 
of Frank Hawks, Roscoe Turner, Kingsford-Smith and 
others. Women pilots, among them Ruth Nichols, 
Amelia Earhart, and Jacqueline Cochran, also helped 
to set some of the early records. 

Round-the-world flying became a popular test. In 
1931, Wiley Post, with Harold Gatty as navigator, 
made such a flight in a single-engine Lockheed— T/ie 
Winnie Mae— in a little more than eight days. In 1933, 
Post did it alone in seven days. This record stood until 
1938 when Howard Hughes and a crew of four in a 
twin-engine Lockheed flew the 14,791 miles in some- 
what less than four days. In February, 1949, Captain 
James Gallagher and the crew of a United States 


Air Force B-50-Thb Lucky Lady //-flew non-stop 
around the world in 94 hours and one minute. In April 
1964, Mrs. Jerrie Mock, a Columbus, Ohio, housewife 
became the first woman to complete successfully a 
solo round-the-world flight. 

Year by year, world speed records were steadily 
improved: Al Williams-266 mph in 1923; Adjutant 
Bonnet of France-278 mph in 1924; James Doolittle— 
294 mph in 1932; James R. Wendell-304 mph in 1933; 
Raymond Delmotte of France— 314 mph in 1934; 
Howard Hughes— 352 mph in 1935; and then the 
Germans forged ahead with Herman Wunster flying 
379 mph in 1937 and Fritz Wendell-469 mph in 1939. 

These surprising increases in speed set the stage 
for a new type of aircraft, the jet-powered airplane. 
On August 27, 1939, a German Air Force captain flew 
a Heinkel 178 with a turbojet engine. This German 
achievement was quickly followed by a successful 
British jet-powered aircraft in May 1941. But the 
honor of being the first man to break the sound barrier 
goes to an American flying an American-designed and 
manufactured airplane. On October 14, 1947, Capt. 
Charles (Chuck) Yaeger, in a Bell X-1, flew at a 
speed of Mach 1.45 (968 mph); on December 12, 
1953, he flew at two and a half times the speed of 
sound. In e.xactly 50 years to the month, man had 
developed and refined aircraft construction and engine 
design to such a degree that speed had progressed 
from 7 mph to 1,650 mph. 

Recently new world records in several categories 
were established. In 1961, A. Fedetov, a Russian, flew 
a P-166 jet 1,491.9 mph over a closed-circuit course. 

Then in 1962, Maj. Clyde Evely and his USAF crew 
flew 12,532.28 miles in a B-52H, a non-stop "distance 
in a straight line", from Okinawa to Madrid. Maj. 
Robert M. White set an altitude record of 314,750 ft. 
in the X-15-1, and the Russian Gueorgui Mossolov flew 
an E-166 jet at 1,665.89 mph over a "straight course". 

Air-Mail and Air-Passenger Transportation 

Air transportation as a commercial enterprise had 
its beginning in the carrying of the air mail. Air-mail 
service began in the United States as an experiment, 
in September, 1911, when a temporary post office was 
set up on the outskirts of Mineola, New York. During 
the period of a week, mail was flown from the edge 
of this Long Island town to the post office in the town. 

There were further small-scale experiments, and 
in 1912 the Post Office Department asked Congress 
for the modest sum of $50,000 with which to initiate 
a regular air-mail service. It was not until 1916, how- 
ever, that Congress finally made some funds available. 
The Post Office Department advertised for bids for 
air-mail service, but no one submitted an offer since 

there were no airplanes of suitable construction for 
the purpose. 

In 1918, Congress appropriated $100,000 for the 
establishment of an experimental air-mail route, and 
in May of that year the first official air mail route 
linked the cities of New York and Washington. By 
1921 the first transcontinental air-mail route was 
formed, with the first flight, a dramatic milestone in 
air transportation history, being made in 33 hours 
and 21 minutes. 

After air-mail service had been operated by the 
Post Office for several years. Congress, in 1925, passed 
the Air Mail Act (Kelly Act) which made provision 
for the carrying of air mail by private contractors. 
The Kelly Act provided the impetus which aroused 
private industry and capital to the opportunities in the 
field of air transportation. By 1927, private contractors 
had accepted responsibility for all air-mail routes, 
rapidly expanding this service to many new cities 
while planning for the coming era of passenger service. 

The last air-mail route to be turned over to private 
contractors was the transcontinental route. William E. 
Boeing, an airplane builder, submitted the low bid 
and within five months had put into operation 25 new 
and specially constructed mail planes. This particular 
air-mail operation formed the nucleus of what was 
later to become United Air Lines. 

Because of the pioneering done by air-mail pilots, 
the enactment of the Kelly Act and the Air Commerce 
Act of 1926, and the surge of interest by industry in 
the development of better planes, more powerful en- 
gines, and increasingly useful navigational aids, air- 
passenger and freight transportation have been able 
to assume an important role in American life. 


Since the beginning of recorded history there have 
been evidences of man's desire to fly. When early man 
realized his inability and helplessness to soar through 
the air, he assigned the ability to fly only to his gods. 

Archytas's wooden pigeon, about 400 B. C. was the 
first concrete evidence of man's attempt to construct a 
flying machine. Leonardo da Vinci, however, was the 
first to work out plans intelligently for flying devices, 
including ideas for a propeller and a parachute. 

The first glider pilot was a Frenchman, Besnier. He 
glided successfully in 1678. Man first left the ground 
for extended periods in balloons. The Montgolfier 
brothers accomplished this feat in 1783. During the 
following 125 years balloons, airships, and zeppelins 
were constantly improved. 

Sir George Cayley, an Englishman, Octave Chanute, 
a Frenchman, Otto Lilienthal, a German, and Profes- 
sors John J. Montgomery and Samuel P. Langley, 


Americans, greatly influenced the experiments of the 
Wright brothers. 

After experimentation with gliders and the devel- 
opment of a suitable engine, a satisfactory rudder, and 
a workable propeller, the Wright brothers achieved 
lasting fame by being the first men to fly a heavier- 
than-air craft at Kitty Hawk, N. C, on December 17, 

In rapid succession, the Atlantic and Pacific Oceans 
were spanned. New speed and altitude records were 

constantly being set. Round-the-world flights became 

Engine and airframe design continued to improve. 
The first turbojet airplane was built and flown in 1939. 
Supersonic flight followed soon thereafter. 

In the 1920's, the United States Post Office Depart- 
ment encouraged and subsidized the first air-mail 
routes. These routes, with the pilots and planes con- 
cerned, provided the nucleus for the development of 
the modem-day airlines. 


1. What was the Kelly Act and why was it impor- 

2. When and where was the first jet airplane suc- 
cessfully flown? 

3. What was the role of Count Zeppelin in the 
development of the airship? 

4. Trace the development of air-mail service from 
1911 to 1927. 

5. Of what significance in aviation history are the 
dates 1909, 1919, 1927, and December 12, 1953? 

6. What was the importance of da Vinci's research 
and planning? 

In what type of device did man first leave the 

What were the limitations of the free balloon? 
In what way did the Wright brothers use gliders? 
Name the contributions of Sir George Cayley to 
gliding flight. 

Who developed the rudder and how does it 
control the airplane? 
12. What formed the basis for our present widespread 
commercial air transportation? 


Chapter 3 Theory of Flight 

Whenever, in casual conversation, a group of peo- 
ple start to discuss airplanes, someone is almost cer- 
tain to exclaim, "Why, some of those airplanes weigh 
tons. I don't see how they stay in the air." Very few 
people understand the forces that control an airplane 
in flight. 

For many years engineers have studied the motion 
of air over airplane parts in order to learn how a 
change in the shape of the part affects the force 
created on it by the moving air. Although a large 
amount of information is presently available on this 
subject, the desire to make airplanes go higher, faster, 
farther, and carry greater loads requires continuous 

A balloon rises in the air because its bag, which is 
filled with a gas lighter than the air at low altitude, 
displaces the heavier low altitude air. The difference 
between the weight of the heavy air displaced and 
the light air inside the bag equals force, and force is 
the element which lifts the balloon. Air gets lighter 
as altitude increases; consequently, at an altitude 
where this weight difference between the air in the 
bag and the displaced air is equalized, the balloon 
stops rising and remains at that altitude. Balloons are 
referred to as lighter-than-air craft. 

Figure 8 — An exaggerated view of air movement around a wing 
moving through the air at a relatively high speed. The pressure on the 
upper wing surface is less than on the lower causing a force, called 
lift, to be directed upward. 

The airplane does not get its lift in the same man- 
ner as the balloon; in an airplane, lift depends upon 
the relative motion between wing and air. Airplanes, 
therefore, are referred to as heavier-than-air craft. 

To understand how very large loads are carried 
by airplanes, one should realize that each square foot 
of wing area can lift a certain weight at a certain 
speed. By increasing the wing area— lift— larger loads 
can be raised. The lift developed by a specific wing 
will depend upon its shape and size, the speed at 
which it moves through the air, and the angle at which 
it strikes the air. 

Shape of the Wing 

Imagine that a wing is cut along a line drawn be- 
tween its front edge ( leading edge ) and its rear edge 
(trailing edge). This cross-section will expose a por- 
tion of the wing that shows the shape of the airfoil. 
This airfoil will be rounded at the leading edge and 
sharp at the trailing edge in those airplanes which 
are not designed to fly at supersonic speeds. The 
upper surface of the airfoil is curved and the lower 
surface is almost flat. The thickest part of the airfoil 
lies approximately one-third to one-half the distance 
between the leading edge and the trailing edge. (Fig- 
ure 8.) 

When looking down at the airplane, one sees the 
span. The span is the distance from one wing tip to 
the other. The chord is the distance between the lead- 
ing and trailing edges. The span is usually between 
five and ten times as long as the chord. A wing with a 
large span in comparison to the chord has less resist- 
ance to motion through the air (drag) than does a 
wing with a small span in comparison to the chord. 

Speed of the Wing 

If we move the wing through the air at a relatively 
high speed with the rounded or leading edge forward, 
the following things happen: The blunt and thick 


leading edge pushes the air out of the way. Part of 
this displaced air flows rapidly (the speed is impor- 
tant) over the wing and part of it flows under the 
wing. The layers of air, after going over and under 
the wing, join again behind the trailing edge. The 
important thing to remember is that due to the curved 
upper surface the air that flowed over the wing had 
to go farther than the air that went under the wing. 
Consequently, air that flowed over the wing had to 
travel faster than the air that went under the more or 
less flat bottom surface. 

The air which had to travel farther across the top 
of the wing is stretched out and becomes thinner, 
creating a reduced pressure on the upper surface. 
The air traveling along the bottom of the airfoil is 
slightly compressed, and consequently develops in- 
creased pressure. The difference in pressure between 
the air on the upper and lower surfaces of the wing, 
when exerted on the entire wing area, produces lift. 
(Figure 8.) 

The faster the wing is moved through the air the 
greater the pressure difference will be, with a result- 
ing increase in total lifting force. The heavier an air- 
plane is in relation to its total wing area, the higher 
the speed must be to develop enough lift to get it 
off the ground and sustain flight. 

Lift and Angle of Attack 

There is another element that affects the amount 
of lift produced by a wing, i.e., the angle at which 
the wing strikes the air. If the wing is held flat and 
moved straight ahead, some Ifft is generated. More lift 
is obtained, however, if the leading edge of the wing 
is elevated slightly above the trailing edge, i.e., if 
the wing goes through the air at a higher angle of 

At a higher angle of attack the wing displaces more 
air; that is, it makes the air over the wing travel far- 
ther, and, up to a certain point, develops more lift. 
However, every wing has a stalling angle of attack 
at which lift drops off abruptly. This sudden loss of 
lift (stall) is caused by the swirling and burbling of 
the air over the top surface of the wing (Figure 9) 
and occurs when the angle of attack is so great that 
it exceeds the angle necessary for maximum lift. When 
an airplane stalls, the nose drops, the speed increases, 
and the angle of attack decreases. If, however, both 
the nose and one wing drop, the airplane will rotate 
hke a leaf falling from a tree. This flight attitude is 
called a tail spin, and, although the nose is down and 
the airplane is diving, the new angle of attack exceeds 
the stalling angle. To compensate for this unusual 
diving attitude, the pilot must first lower the nose 

still farther, reduce the angle of attack below the 
stalling value, stop the rotation, and then bring the 
airplane back to a straight and level flight attitude. 

Lift and Weight 

The amount of the lift, then, is determined by 
(1) the shape of the wing, (2) the speed of the air- 
plane, and (3) the angle of attack. The amount of 
Itft required depends on the weight of the airplane 
and whether it is flying level, climbing, or diving. 
( Figure 10. ) To climb, the wing's lift must be greater 
than the airplane's weight; during descent the wing's 
lift is less than the airplane's weight. 

Thrust and Drag 

To produce lift, the airplane wing must move 
through the air at a relatively high speed. This high 
speed is produced by a force or thrust which is ex- 
erted in the direction of the airplane's motion. Both 
a propeller and a jet engine produce thrust. 

The blades of a propeller are small wings. When 
they rotate they create forces in the same manner as 
the wing creates Ifft except that the forces on the 
propeller blades act in the direction of the airplane's 
motion and are called thrust. A jet engine bums a 
mixture of fuel and air and exhausts this mixture 
toward the rear of the airplane. A force exerted inside 

Figure 9 — Lift increases as the angle of attack is increased, up to a 
certain point. Wtien the angle of attack becomes too greet, however, 
the air seporates from the upper surface, destroying the smooth flow, 
and reducing the lift. 


the jet engine and in an opposite direction to the 
movement of the gas is needed to exhaust this gas 
at a high speed. This force, also, is in the direction of 
the airplane's motion and is called thrust. 

The amount of thrust required depends upon the 
airplane's drag, and upon whether it is climbing, div- 
ing, or flying straight and level. Drag is the resistance 
an airplane meets in moving through the air. The 
faster the airplane moves, the greater will be the drag. 
Moving air exerts a similar force against the body 
when one tries to stand in a high wind. 

In level flight, if the airplane speed remains con- 
stant, thrust is equal to drag. (Figure 11.) To accel- 
erate the airplane, thrust must be greater than drag 
and additional thrust is produced by burning more 
fuel in the engine. If thrust is increased, the airplane 
speeds forward until drag again equals thrust, and 
the airplane once more flies at a constant speed. As the 
speed increases, lift also increases; consequently, it is 
necessary to reduce the wing's angle of attack by low- 

Figure 10 — Lift must exactly equal the 
to maintain steady flight. 

iight of an airplane in order 

Figure 11 — When the airplane 
to the drag. 

not accelerating, the thrust is equal 

ering the airplane's nose so that lift will again equal 
the airplane's weight and the aircraft will remain in 
a straight-and-level flight attitude. 

Thrust must also be increased if the airplane is to 
climb at approximately the same speed it maintained 
while it was in level flight. To get the additional lift, 
the angle of attack must be increased, but this flight 
attitude also increases the drag. Additional thrust, 
therefore, is needed to counteract the additional drag 
and lift the airplane to its new altitude. During take- 
off, maximum engine power is used to accelerate the 
airplane and cause it to climb rapidly. During descent, 
the weight of the airplane helps to overcome drag, 
thereby requiring less thrust to maintain a constant 
air speed. 

Drag greatly affects the amount of thrust required 
for various flight attitudes. To obtain the desired air- 
plane performance with minimum engine weight and 
fuel consumption it is necessary to minimize thrust. 
Consequently, airplane designers have studied the 
shape of various airplane parts to discover which 
shapes offer the least resistance to the movement of 
air across their surfaces. Those which have been found 
to have the least drag and which permit the air to 
flow smoothly over their surfaces are called stream- 
lined shapes. They require the least thrust to move 
them through the air. 

Inherent Stability 

To fly properly, an airplane must be designed so 
that all the forces applied on it during flight will bal- 
ance. In other words, the airplane must be stable 
enough to fly straight and level with a minimum of 
physical control by the pilot, i.e., the pilot must be 
able to change the plane's direction or cause it to 
climb or dive easily. 

If the reader has built model airplanes, he will have 
discovered that before they will fly they must be 
balanced and the distribution of weight equalized. 
An airplane that is tail-heavy, nose-heavy, or one- 
wing-heavy is badly balanced. The airplane's center 
of gravity is that point about which the airplane bal- 
ances. It should be near hut always just ahead of the 
center of lift. This is the first consideration for inher- 
ent stability, or "built-in stabilit)'." 

If a sheet of paper is skimmed through the air, it 
will fly an erratic and unpredictable flight path rather 
than a straight line. If the sheet of paper is folded 
into a dart shape, it will do better, but it will still 
turn and roll erratically. It has only a minimum 
amount of inherent stability. A carefully built model 
airplane, however, flies straight and level unless it is 
blown off course bv air currents. The stabilizers built 




Figure 12 — An airplane may be controlled about tlie three axes of pitch, yaw and roll 

into a model airplane are the same, in principle, as 
those used on an airplane. 

The vertical stabilizer is a fixed tail airfoil which 
stands upright. It prevents the airplane from yawing, 
i.e., swinging left or right. The horizontal stabilizer, 
like a small wing, is the horizontal part of the tail. 
It prevents the airplane from nosing up or down. 

There is still another way in which an airplane can 
move. It can roll, wing down or up. Consequently, 
wings are constructed and positioned on an airplane 
so that they tend to keep the airplane stable in roll. 

The Axes of Rotation 

An airplane is free to turn in three planes, whereas 
an automobile turns in only one plane. Think of an 
airplane as having three axes of rotation, all passing 
through the center of gravity. The longitudinal axis, 
or axis of roll, extends lengthwise through the air- 
plane's fuselage; the lateral axis, or axis of pitch, goes 
lengthwise through the wings; and the vertical axis, or 
axis of yaw, is perpendicular to the other two, and 
perpendicular to the earth's surface when the airplane 
is in straight and level flight. (Figure 12.) 

To illustrate these rotations cut a piece of card- 
board into a rough airplane shape, and follow this 

explanation: Turn to the left or right around the 
vertical axis. That is called the axis of yaw and is the 
only axis about which you can turn an automobile. 

Now put the nose down and the tail up, or the nose 
up and the tail down. That is called rotation about the 
axis of pitch, or lateral axis. By controlling that rota- 
tion you put an airplane in the proper position to 
climb or dive. Next roll the left wing down and the 
right wing up, or the other way around, and you have 
rotation about the axis of roll, or the longitudinal axis. 

To control the flight path of the airplane around its 
three axes, movable control surfaces are used: the 
rudder, elevator, and ailerons. 


Movement about the axis of yaw is controlled by 
the rudder, and the rudder is controlled by foot pres- 
sure on the cockpit's rudder pedals. (Figure 13.) 
When pressure is applied to the right rudder pedal, 
the nose of the airplane swings to the right. When 
pressure is applied to the left rudder pedal, the nose 
of the airplane swings to the left. The nose swings 
because the action of the rudder pedal turns the 
hinged rudder away from the longitudinal axis, and 
as the air strikes the rudder it literally pushes the tail 
of the airplane to the opposite side. 


^ \l 



Figure 13 — Pushing the left-rudder pedal moves the rudder to the left 
causing the airplane to rotate to the left about its vertical axis. Push- 
ing the right-rudder pedal mokes the airplane rotate to the right. 


Movement around the axis of pitch is controlled 
by the elevators, as shown in figure 14. The elevators 
respond to forward and backward pressure on the 
control stick or wheel. In normal flight when forward 
stick is applied, the nose of the airplane is lowered. 
This action is caused by the lowering of the elevators 
which, as the wind strikes the elevator surface, forces 
the tail up and the nose down. The reverse action 
occurs when the stick is moved backward. 

Figure 14 — Forward movement of the stick lowers the elevators caus- 
ing the airplane to nose down with rotation about its lateral axis. 
Backward movement of the stick raises the elevotors causing the air- 
plane to nose up. 


Movement around the axis of roll is controlled by 
the ailerons. The ailerons respond to sideways pres- 
sure applied to the control stick as shown in figure 15. 
Pressure applied to the stick toward the left depresses 
the left wing. Pressure on the stick toward the right 
depresses the right wing. The ailerons are linked to- 
gether by control cables so that when one aileron 
is down, the opposite aileron is always up. As in the 
case of the elevators and rudder, the wind strikes the 
obstructing surfaces, raising the wing whose aileron 
is down, lowering the wing whose aileron is up, thus 
turning the airplane around its longitudinal axis. 

Coordination of Controls 

Control pressures are not used separately. The sim- 
plest maneuver needs coordination of all three pres- 
sures. A simple turn to the left requires coordinated 
pressures on the rudder, elevator and ailerons. 

Trim Tabs 

Even though an airplane has inherent stability, it 
does not always tend to fly straight and level. Remem- 
ber that the weight distribution in an airplane affects 
its stability and that various speeds affect the air- 


Figure 15 — Movement of the stick to the pilot's left raises tlie left 
aileron and lowers the right aileron, causing the airplane to bank to 
the left. Similarly, right stick bonks the airplane to the right. 

plane's flight characteristics. If the fuel from one wing 
tank is completely used before fuel is used from an- 
other tank, the airplane tends to roll toward the full 
tank. All these variations require a pilot to exert addi- 
tional pressure on the controls for correction. 

WhUe climbing or gliding, it is necessary to exert 
pressure constantly to keep the airplane in the desired 

attitude. This constant control pressure is tiring in a 
small airplane, exhausting in a medium-size airplane, 
and impossible for any length of time in a heavy 

For this reason airplanes are constructed with trim 
tabs. Trim tabs are small, hinged, control surfaces 
attached to the main control surfaces, i.e., rudder, 
elevators, and ailerons. (Figure 16.) Trim tabs are 
controlled by rotating a crank or a wheel in the 
cockpit or by pushing a button which electrically 
moves the tabs. By using trim tabs the pilot can bal- 
ance the forces on the controls so that, with hands off 
the controls, the airplane will fly either straight and 
level or in a climbing or gliding attitude. Trim tabs 
actually operate like the control surfaces to which 
they are attached. That is, if the rudder tab (Fig- 
ure 17) is set toward the left, it pushes the rudder to 
the right, thus making the airplane yaw to the right. 


Figure 16^This drawing shows location of trim tabs which ore ad- 
justed by the pilot to produce straight and level flight, constant climb, 
glide, etc. 

Figure 17 — Diagram Showing How the Airstream Acts on the Rudder 
Trim Tab to Push the Rudder to the Right 



Lift is the force which raises the airplane off the 
ground and sustains it in the air. The hfting surface, 
or wing, is shaped so that when it passes rapidly 
through the air it produces the greatest amount of 
lift in proportion to the smallest possible amount of 

The amount of lift can be varied by changing the 
angle at which the wing strikes the air. This angle 
is known as the angle of attack. If the angle of attack 
is too great, as in an extremely steep climb, the air 
will cease to flow smoothly over the top of the wing, 
lift will be destroyed, and the airplane will stall. 

Lift acts in the opposite direction to the weight, 
i.e., when lift exceeds weight the airplane climbs and 
when lift is less than weight the airplane descends. 

In order to propel the airplane through the air rap- 
idly enough to maintain lift, the airplane must have 
thrust. Thrust acts in a direction opposite to drag. 
Drag is the resistance the airplane encounters while 
moving through the air. In normal level Hight at con- 
stant airspeed, lift balances weight and thrust balances 

These four forces— lift, weight, thrust, and drag- 
must be controllable by the actions of the pilot so that 
the airplane can climb, glide, accelerate, decelerate, 

etc. However, in order that these forces may be easily 
controlled, the airplane must be very carefully bal- 
anced. In other words, it must be stable. 

Special airfoils are built into the airplane to achieve 
this stability. The horizontal stabilizer tends to keep 
the airplane from pitching, the vertical stabilizer as- 
sists in keeping the airplane from swinging to the left 
or right, while the wings are designed and placed on 
the airplane so that they tend to keep it from rolling. 

So that the pilot may be able to force the air- 
plane to rotate around one or more of its axes, control 
surfaces are supplied. The rudder swings the nose of 
the ship left or right around the airplane axis of yaw 
(vertical axis), the elevator forces the tail of the air- 
plane up or down (lateral axis), while the ailerons 
bank the wings left or right around the axis of roll 
(longitudinal axis). Although in conventional air- 
planes these controls are separate and distinct, they 
must be coordinated in most maneuvers in order to 
produce the proper flight action. 

Additional controls required in all large airliners, 
and desirable in small planes, are the trim tabs. These 
small control surfaces, located on the rudder, the 
ailerons, and the elevators, assist the pilot by deflect- 
ing the control surfaces just the right amount to keep 
the airplane at the desired attitude. 


1. What is lift? 

2. Describe how wing lift is affected by its: 

a. Airfoil shape. 

b. Speed through the air. 

c. Angle of attack. 

3. What is the general shape of an airfoil? 

4. What happens to the air when a wing is moved 
through it at a relatively high speed? 

5. How much lift is required? 

6. What is thrust? Drag? 

7. How much thrust is needed? 

8. What are the relationships between thrust-drag 
and weight-lift in straight and level flight? 

9. For what reasons is stability important? 

10. What is inherent stability? What are the consid- 
erations for it? 

IL What are the stabilizing surfaces and their func- 

12. What are the axes of rotation? 

13. What controls the airplane around each axis? 

14. What is a trim tab? Where are they placed? For 
what reason? 


Chapter 4 Aircraft 

The airplane of today is far removed from the 
flimsy, kite-like, underpowered craft of 1903, and 
there is much evidence that this advancement wOl 
continue in the years to come. Following World War I 
the airplane became an intricate and complex product 
of skilled, precision workmanship, possessing quali- 
ties of high performance and dependability. The great 
role played by the airplane in World War II was a 
direct result of the continued refinement of the design 
techniques and the manufacturing skills that gave the 
airplane ever-increasing performance and utility. 

Since the last great conflict, the airplane has been 
widely accepted by both civilian and military users. 
Due to this increased use, the aircraft and allied in- 
dustries now employ more persons than any other 
industry in the United States. Aircraft production has 
created many new jobs, and there is an ever-increasing 
need for new processes, new materials, and new skills. 

Aircraft are divided into two general classes: 
heavier-than-air craft and lighter-than-air craft. The 
major emphasis today is on the airplane with its many 

variations in design, type, size, construction, and 
power. It is the purpose of this chapter to describe 
the basic types of airplanes and their principal 

General Structure of an Airplane 

Structurally, the airplane is usually divided into five 
main sections, i.e., (1) wings, (2) fuselage (or hull, 
in the case of a flying boat), (3) tail assembly, (4) 
landing gear, and (5) powerplant (which includes 
the propeller, if there is one. ) ( Figure 18. ) 

A visit to any large airport will show that airplanes 
are either monoplanes, with one wing (figure 19), or 
biplanes, having two wings (figure 20). Early at- 
tempts to build airplanes with still more wings proved 
to be unsatisfactory. The monoplane is now consid- 
ered more efficient than the biplane and consequently 
is in widespread use for commercial, military, and 
private flying. Biplanes today are used principally for 
crop spraying and instructional purposes. 

Figure 19 — Monoplane 

Figure 20 — Conventional Biplane Showing Upper and lower Wings 
and Wing Struts 


Figure 21 — Various Wing Shapes 


Figure 22 — Possible Wing Locations 


Frgore 23 — Diagra 
curved ribs, cros 

truction including the 

Monoplanes may be classified according to the loca- 
tion of the wings on the fuselage and the shape of the 
wings. The wings, which may also be used to cany 
the fuel tanks and engines, may be mounted high, 
low, or in the middle of the fuselage and may be of 
several different shapes. (Figures 21 and 22.) 


In general, wing construction is very similar in all 
types of airplanes. Briefly, the main structure of a 
wing consists of two long spars of aluminum alloy 
running outward from the fuselage end of the wing 
toward the wing tip. ( Figure 23. ) Curved ribs are 
secured to the spars and covered with thin aluminum 
alloy "skin" to give the wing its familiar curved shape. 
In the case of some light airplanes the spars are made 
of wood, and the skin is tightly stretched cotton or 
linen fabric which is painted with "dope" to give it 
a tough, weather resistant surface of the proper shape. 

Wings are secured to the aiqilane fuselage by using 
one of two systems. The first is the full cantilever type 
in which the wing structure is made very strong and 
is fastened to the airplane fuselage without any exter- 
nal struts or wires. 

The second system is the externally braced wing 
in which heavy struts or streamlined wires extend 
from the wing to the fuselage. In this case the wing 
may be of lighter construction than the full cantilever 
type, but the struts or wires increase the amount of 
drag and thereby reduce the speed of the airplane. 
The modern achievement of high-speed aircraft is 
partially due to the elimination of such external brac- 
ing as struts and wires. The externally braced wing 
construction is now used only on the slower and less 
expensive light planes. 

As a part of the trailing edge, or rearmost part of 
the wing, and outboard toward the tips, are the 
ailerons, controlled by sideways pressure on the stick 
or by rotation of the control wheel. The purpose of 

the aileron is to produce a rolling or banking motion. 
In the area of the trailing edge of the wing, between 
the ailerons and the fuselage of some airplanes, are 
the flaps. Flaps are hinged devices which vary the 
camber or curvature of the wing. ( Figure 24. ) Correct 
use of the flaps in flight is to steepen the gliding 
angle without changing the gliding speed. Flaps 
shorten the landing roll primarily by allowing a lower 
landing speed, not by adding resistance, although the 
latter is also a factor. In actual use, the flaps are often 
raised during the landing roll so that lift is decreased 
and more weight is placed on the wheels. This is done 
to give the tires better traction for their braking ac- 
tion. Flaps are usually used for resistance only under 
conditions of poor tire adhesion, i.e., ice or snow on 
the runway. They may be used during takeoff to 
increase the lift of the wing, thereby shortening the 
distance of the takeoff run. 

Flaps are controlled directly by the pilot, using 
either a simple lever arrangement or, in the case of 
larger airplanes, levers actuated by a hydraulic pump 
or by an electric motor. Frequently the flap control sys- 
tem selected by the airplane manufacturer will also 
be used to raise and lower the landing gear. In the 
wings of some airplanes may be found slots, which 
are high-lift devices located in the leading edge of 







Figure 24 — A drawing showing the location of flops which in a low 
ered position (as shown) will steepen the gliding angle and may resul 
in a shorter landing run. 

the wing in front of the ailerons. Their function is 
to improve the airflow over the wing at high angles 
of attack, thereby lowering the stalling speed. (Fig- 
lue 25.) 


The airplane fuselage is the main body of the air- 
plane and carries the crew, controls, passengers, and 
cargo. It must be constructed so that it has great 
strength for its weight, provides enough room, and 
has a proper streamlined or aerodynamic shape. The 
fuselage, called the hull in a flying boat (figure 26), 
may also contain the engine and fuel tank. An am- 
phibian is an airplane whose hull is equipped with 
retractable wheels to enable it to operate from either 
land or water. (Figure 27.) 

Fuselages are classified according to the way in 
which the structure has been built. The two main 
types of construction are the truss and the semi- 
monocoque. (Figures 28 and 29.) The first is made of 
steel tubing; the second with an internally braced 
metal skin. 

Regardless of the attitude or position of an air- 
plane, i.e., parked, taking off, landing, flying straight 
and level, turning, or performing acrobatic maneu- 
vers, there are always stresses on the fuselage struc- 
ture. The bracing of the welded steel-truss type acts 
like the structure of a bridge, since loads will be dis- 
tributed by the parts to the entire fuselage. The semi- 
monocoque gets its strength from the metal skin or 
shell which is reinforced by the internal bulkheads 
and stringers. 

Tail Assembly 

The empennage, or tail assembly of an airplane 
(figure 18), is composed of several parts, each of 
which has a definite control function. The horizontal 
stabilizer prevents the nose of the airplane from pitch- 
ing up and down. The elevator, a hinged portion of 
the horizontal stabilizer, controls the angle of attack. 
The vertical fin helps to maintain the diiection of 
flight. The rudder swings the nose right or left and, 
in conjunction with the ailerons, is used to make co- 
ordinated turns. These surfaces are of many sizes and 


Figure 25 — Wing Slots Diagram. On the left side, the normal flow of 
oir over the wing is observed. Note the burble or breokdown of smooth 
flowing air in the stall condition without slots and then compare the 

air flow over the slotted 
diagram on the right. 

■ing at the same angle of ottock in the 


Figure 17 — Amphib 
wheels (retraclabl 

Figure 28 — Welded Sleel Tubular Fuselage 

Figure 29 — Semi-Monocoque Fuselage 

Figure 31 — Tricycle Landing Gear 

shapes, and there are many variations in positioning 
the vertical and horizontal elements. 

Frequently, in discussing control surfaces, the term 
balanced control is employed. This merely means that 
the control, whether aileron, elevator, or rudder, is so 
arranged and operated that when the pilot moves any 
control some aerodynamic force is set in motion to 
assist him. Normally the pilot's strength would be the 
only force exerted in moving the control surfaces. 
However, when balanced controls are used, pressure 
of the air strikes the balanced section which is forward 
of the hinge, thus exerting a force on both sides of 
the hinge and making it easier for the pilot to move 
the control in the desired direction. 

In very large airplanes, and those capable of super- 
sonic speed, it is necessary to give the pilot additional 
assistance in moving the controls. This is accomplished 
by the use of servo units, which are electrically or 
hydraulically operated mechanisms which move the 
control surfaces in response to the pressures imposed 
on the cockpit controls by the pilot. 


Figure 32 — Landing Gear Being Retracted 

Landing Gear 

An airplane's landing gear may be the conventional 
type, with two main wheels and a tail wheel, (figure 
30), or it may be the tricycle type, with two main 
wheels and a nose wheel, ( figure 31 ) . The wheels may 
be fixed or retractable, i.e., folding into the fuselage or 
wings, (figure 32). 

To take up the impact of the landing, the wheels of 
most airplanes are attached to oleo struts, which are 
shock-absorbing devices that use oil to cushion the 
blow. (Figure 33.) This type of shock absorber is 
located in the landing gear struts to which the wheels 
are attached, and is composed of an outer cylinder 
fitted over a piston. The piston is on the end of a short 
strut attached to the wheel axle. Between the piston 
and a wall or bulkhead in the outer cyhnder is a space 

filled with oil. The impact of the landing pushes the 
piston upward, forcing the oil through a small opening 
in the bulkhead into the chamber above it, thereby 
cushioning the shock. 

On some light airplanes tlie shock of landing is re- 
duced by the use of sltock cords. These consist of 
many rubber bands tightly bound into a bundle with 
a cloth covering. They tend to cushion the landing by 
stretching and thereby distributing the impact over 
a greater period of time. The same principle is em- 
ployed by other light planes equipped with landing 
gear struts made of spring steel. Just as the rubber 
shock cords stretch to give the effect of a soft landing, 
so the steel struts accomplish the same end by bending 
outward as the wheels make contact with the runway. 

To aid in controlling airplanes on the ground, the 
main wheels are equipped with brakes which may be 



Figure 33 — Principle of Oleo Strut Operation 

operated separately or together. Brakes are used not 
only to slow up a fast rolling airplane but also as an 
aid to steering and parking. For example, pressure on 
the left brake and slightly advanced throttle will cause 
the airplane to turn to the left around the left wheel. 
As little use as possible is made of brakes, because the 
weight and speed of the airplane may result in over- 
heating and subsefjuent damage to the brake mech- 

Special types of landing gear include skiis for snow 
and ice and floats for water. For carrier landings, air- 
planes are equipped with an arrester hook that catches 
in a system of cables on the flight deck, bringing the 
airplane to a stop in a short distance. 


Lack of suitable power retarded the development of 
the airplane for many years. After an adequate engine 
was devised it more than kept pace with the changes 
in the airframe structure. 

A commonly-used powerplant is the internal com- 
bustion gasoline engine. This type of powerplant may 

consist of as few as four cylinders or as many as 
twenty-eight. The cylinders of the smaller engines are 
arranged in a horizontally-opposed fashion, while 
those having more than six cylinders are arranged 
radially around the crankshaft. (Figure 43) The num- 
ber of individual engines required by an airplane is 
determined by the horsepower needed to provide the 
necessary thrust. WhUe a single engine may adequately 
supply the horsepower requirements for a small light 
plane, as many as foiu" may be needed on a large 

Engines may be mounted in several ways. The 
tractor type has the propeller attached to the front 
of the engine and pulls the airplane through the air. 
The pusher, as its name implies, pushes the airplane 
by having its propeller attached to the rear of the en- 
gine. Single, tractor-type engines are usually mounted 
in the nose of the fuselage. Airplanes with two or more 
engines may have their powerplants mounted in the 
wing, atop the wing, or under the wing. 


Converting the energy of the engine's revolving 
crankshaft into a pidling or pushing force is accom- 
plished by the propeller— a rotating airfoil providing 
the forward thrust for airplanes and airships. Propel- 
lers can have two, three, or four blades and can vary 
greatly in their configuration. Some have long slender 
blades, while others are broad, with short square-cut, 
paddle-like blades. Occasionally two counter-rotating 
propellers are driven by a single engine. 

The propeller derives its pulling or pushing effect 
from the angle at which the blade is set on the hub. 
This angle is called pitch. The pitch or blade angle 
may be changed automatically, by mechanical means 
or by hand, in order to give the propeller its greatest 
efficiency. Low pitch, or a flat blade angle, provides 
higher revolutions per minute while high pitch, or a 
greater blade angle, gives lower revolutions. (Figure 

Propellers are classed as fixed pitch, a blade angle 
that cannot be adjusted; adjustable pitch, a blade 
angle that can be changed only on the ground; con- 
trollable pitch, a blade angle that can be changed by 
the pilot from the cockpit; and constant speed, a blade 
angle that automatically adjusts itself according to the 
amount of power used. Some constant speed propellers 
may be feathered, i.e., their blades may be turned so 
that the leading edges are aligned with the line of 
flight. (Figure 35.) Feathering a propeller stops a 
disabled and vibrating engine, decreases the drag of 
the propeller, and increases the performance of the 
airplane while operating with the remaining engine 
or engines. (Figures 36 and 37.) Propellers may also 

have reversible pitch for use as a landing brake. In 
this type, the blade angle is shifted to provide thrust 
in the opposite direction. 


low ar 
each n 

34-1 or low pitch, high RPM for take-off (blades have 
'9le of attock). 2. Coarse or high pitch, low RPM for cr.isir,q 

''lZ% T.' °' °"°'''- ^ * « °^^ '•"-— -e,ces that 

lOves forward in one revolution 

Figure 35— Full Feathering Propeller. In the left diagram the blades 
ore^set for normol operation while on the right the blades ore feoth- 


Figure 36— Propeller Pitch Performonce Comparisons 



37— Feathered and Unfeathered Propeller Performance 

Jet Propulsion 

The jet engine usually eliminates the propeller and 
provides much greater speed than is possible with the 
propeller-driven, internal-combustion engine. The jet 
engme derives its thrust by compressing the air that 
IS drawn into the front of the engine and combining 
It with fuel which is then burned in the combustion 
chambers. The hot and greatly e.xpanded gases thus 
tormed develop tlirust as they are exhausted out of the 
tail pipe. A portion of the power formed by the burn- 
ing exhaust is used to turn a turbine wheel which 
drives the compressor and other components. The one 
e.xception to the elimination of the propeller is the 
turbo-prop engine, which not only gives forward thrust 
with Its blast of hot air but also gains additional thrust 
from a propeller. (See Chapter V.) 

The jet engine is now widely utilized by the mili- 
tary services, and speeds far in excess of the speed of 
sound are commonplace with jet-propelled military 
au-craft. Like the internal-combustion engine, the jet 


powerplant is frequently mounted in the wing, but 
it is also occasionally suspended below the wing, 
where it is held in place by a mounting structure 
called a pylon. In the modem jet fighter the engine is 
usually located in the fuselage behind the pilot. 

Airplane Accessories 

Many devices are in use today to insure the comfort 
and safety of the passenger and the crew. Many of 
these devices are electronic in nature, such as the 
auto-pilot, which will dutifully perform the work of 
the pilot by flying the airplane and keeping it steadily 
on course. Various other devices are sensitive to the 
presence of fire or smoke in remote areas such as the 
cargo compartment and will immediately sound an 
alarm when such danger occurs. 

Among the mechanical accessories used on military 
and commercial airplanes are de-icer boots. (Figure 
38.) These consist of flexible rubber sheets containing 
inflatable elastic tubing and are mounted in the lead- 

Figure 38 — De-icer Boot Operation. In the top drawing, rime ice has 
formed. In the center, the upper ond lower boot sections have ex- 
panded, cracking off the ice. In the bottom view, the center boot por- 
tion expands, the top and bottom sections collapse, thus completely 
removing the ice. 

ing edge of the wing and tail surfaces. When inflated 
and deflated at regular intervals, they distort and 
stretch the leading edge of the boot in such a manner 
that ice formations crack and blow away. Many metal 
aircraft now use an internal heater, located inside the 
wing just behind the leading edge, which, when acti- 
vated, heats the metal skin and melts any ice which 
may have formed. To combat ice formations on the 
propellers a "slinger" ring may be installed. This dis- 
tributes de-icing fluid along the blades while in flight, 
loosening any ice that may have formed and prevent- 
ing further formation. 

Commercial airliners are equipped with cabin pres- 
surization equipment. This equipment can maintain 
a simulated altitude of two or three thousand feet 
even though the aircraft itself may be flying at twenty 
thousand feet, thereby providing an atmosphere with 
enough o.xygen to prevent drowsiness in the crew and 
permit comfortable breathing by the passengers. 

Other Aircraft Types 

Other types of aircraft include the rotary, lighter- 
than-air craft, ornithopter, and the convertiplane. 
There are two general types of rotary aircraft— the 
helicopter and the gyroplane. 

The rotor blades of the helicopter are merely re- 
volving wings, getting their lift from the motion of air 
over a curved surface in the same manner as the wing 
of an airplane. The revolving blades create an up- 
ward force (lift), and if they are tipped, the heli- 
copter will move in the direction in which the blades 
have been tipped. ( Figure 40. ) 

Due to the rotation of the blades in one direction, 
the helicopter fuselage tends to revolve in the opposite 
direction. To counteract this tendency, the helicopter 
is usually equipped with a small propeller on the tail 
which directs a blast of air sufficient to overcome the 
effects of this torque or turning motion. By increasing 
or decreasing the pitch of the blades of this tail rotor, 
the pilot can control the direction of forward motion. 
Other types of helicopters overcome the undesirable 
effects of torque by incorporating two sets of counter- 
rotating blades. This also provides for a greater lifting 
force and is now commonly used on the larger models. 

The helicopter is unique because it can hover over 
one spot, and for this reason can take off or land in 
a space not much larger than the diameter of the 
rotor blades. A free-wheeling device attached to the 
rotor drive shaft allows the rotor blades to act like 
those of an autogiro by lowering the craft gently to 
the earth in the event of engine failure. 

The gyroplane has unpowered, overhead rotating 
blades for ordinary flight. These blades may be geared 


to the engine for jump takeoffs. Forward flight in an 
autogiro is accomplished by the use of a conventional 
aircraft engine and propeller. 

There are three general kinds of airships— the non- 
rigid, the semirigid, and the rigid. The nonrigid air- 
ship has a streamlined, gas-tight rubberized envelope 
or skin which is not supported by a framework nor 
reinforced by any stiffening materials. It maintains its 
shape by the internal pressure of the gas within the 
envelope. Blimps are the typical example of this type 
of airship. 

The semirigid airship has a structural metal keel 
and a metal cone to strengthen its bow. This reduces 
the bending strains on the envelope and tends to keep 
the airship in its inflated shape lengthwise. The en- 
velope still has to be kept in its flying shape by the 
pressure of the gas within it. 

If inside framework is used to support the gas 
envelope and the airship is not dependent upon the 
inside pressure of the gas to maintain its shape, the 
airship is said to be a rigid type. Since 1938 there have 
been no known rigid-type airships constructed. 

An airship flies because of its lift and thrust. The 
lift comes from the lighter-than-air gas which raises 
the airship into the air. The hull of the airship pro- 
vides a large enclosed space in which the lifting gas 
can be contained. Often the space will be divided into 
separate compartments for the gas. These compart- 
ments are called balloonets. 

Thrust, the force wfiich moves the airship through 
the air, is obtained usually from the engines and pro- 
pellers which are often located in gondolas or cars 
suspended from the hull. These are sometimes called 
"power eggs." 

All airships, either inside or outside the hull, carry 
a car or keel structure, usually of metal, to provide 
space for personnel and cargo, in addition to storage 
room for fuel and equipment. 

Control of an airship is by certain fixed and movable 
surfaces, usually at the stern of the airship, which help 
guide the airship in the same general way as do the 
rudder and elevator of an airplane. Usually the con- 
trols are directed from the control car by connecting 

An ornithopter is an aircraft designed to fly or 
propel itself through air by means of flapping wings. 
This idea is the oldest in the history of flying. Man 
naturally first turned to the flight of birds for ideas to 
aid him in his own desire to travel through the air. 
While some small-scale models have flown, no success- 
ful man-carrying ornithopters have been developed. 

All ornithopters, no matter how varied in design, 
may be classified in two ways. The first type uses 
various forms of wings for support in the air and 

Figure 39— X-18 IN FLIGHT TESTS— Shown is the Id'/j Ion XI 8 dur- 
ing flight tests over Edwords Air Force Base, Calif. Wings have reached 
on angle of oltock of 50 degrees during flight. Now in a ground pro- 
grom to study the effects of downwash during simulated hovering, the 
X-18 is expected to be back in flight tests at a loter date for full 
hovering and vertical operation. 

fastens the wings to the body of a man. The second 
type uses a cabin or cockpit to house the pilot. To it 
the flapping wings are attached and from it the wings 
are operated. 

Early experimenters used the first method. Most 
came to the conclusion that the strength of birds was 
much greater in relation to their weight than man's 
strength in relation to his weight and that it would be 
impossible for man to fly by his own strength alone. 
However, experimenters are still working on this 

A convertiplane is an aircraft so built that it can 
perform, at the will of the pilot, as any one of two 
or more types of aircraft. Some types may be ad- 
justed to fly either as a helicopter, autogiro, or fixed- 
wing aircraft. Aircraft that are essentially converti- 
planes are often called STOL aircraft, meaning that 
they require only a short take off and landing run. 
Still others are referred to as VTOL as they can 
actually take oflF and land vertically. (Figure 39.) 

There are two basic types of convertiplanes. The 
first type looks more like the typical airplane and 
uses the same source of power for forward motion 
that it does for rising vertically or hovering. Thus 
it may rotate its propeller or propellers, or even the 
whole wing structure, from the horizontal to the 
vertical, to change from forward motion to hovering 
flight or a straight-down landing. 

40 — Helicopter 



Figure 41 — Aircraft Safetying Methods 

The second type of convertiplane resembles the 
hehcopter more than it does the fixed-wang aircraft. 
In this type, the rotor axis remains vertical. In for- 
ward flight the rotor blades may be fixed in place, 
allowed to revolve without power, locked in a trail- 
ing position, or folded into the fuselage. These types 
require a propeller or other means for forward 

Convertiplanes usually are powered by the same 
type gasoline or jet engines used by other civil and 
military aircraft. If the convertiplane is using small 
jet engines, it may vary the position of the engines, 
or use diversion valves, so that the thrust will be in 
the direction desired. 

Aircraft Construction 

Modern military and commercial airplanes are con- 
structed chiefly of aluminum and aluminum alloys. 
Other metals such as magnesium, titanium, copper, 
and the many alloys of steel, have characteristics 
which lend themselves well to the construction of 
various aircraft components. Metal parts are joined 
by riveting, welding, soldering, brazing, and special 
adhesives. Parts designed for future disassembly are 
fastened together with nuts, bolts, and screws, or 
other similar devices. Such hardware as nuts, bolts, 
and turnbuckles must be secured so they cannot be- 
come loose during flight. (Figure 41.) This precaution 
is called safetijing, and is accomplished with cotter 
pins, safety wire, airplane safety pins, and elastic 
stop nuts. 

Some light airplanes have components made of 
wood such as spruce, fir, or pine. These woods are 
particularly useful because of their strength-weight 
ratio. Other components require the stiffness that is to 

be found in birch, mahogany, or ash. Wooden parts 
are fastened together with nails and resin or casein 
glues. Cotton or linen fabric, aluminum or aluminum 
alloys, and fiber glass are normally used to cover the 
frame of the airplane. 

Many other materials are required in the production 
of the modern airplane. Of these, the family of plastics 
is playing an ever-increasing role. Synthetics are now 
found in carpet and upholstering materials, windows, 
cable pulleys, electrical insulation, paints and finishes, 
and in many other airplane accessories. In addition, 
such materials as glass, asbestos, leather, rubber, cot- 
ton, and many others have characteristics of some 
particular value in the construction of the airplane. 

Aircraft Inspections 

A program of regular inspections is required of 
every airplane. This government-enforced policy tends 
to insure the continued airworthiness of the airplane 
and is a major factor in the enviable safety record 
established by modern aviation. At intervals not to 
exceed one year the condition of the entire airframe 
and powerplant and all their components is carefully 
examined. In addition to this, all aircraft used as air 
carriers must be submitted for similar inspections, 
determined by the amount of flight time accrued. At 
regular intervals between these periodic inspections 
are others, less detailed in nature and completeness. 
All inspections necessitate the skill and knowledge of 
the airframe and powerplant mechanic, who is re- 
quired, by law, to certificate the work he has com- 

Finally, every airplane should have a preflight in- 
spection in order to maintain further the efficiency 
and safety of the structure, engine, equipment, and 
accessories. Inspection procedure should include the 
powerplant, landing gear, wings, tail assembly, and 
fuselage. Such an inspection is normally the responsi- 
bility of the pilot, or, in the case of a large transport 
aircraft, the flight engineer. 

The following is a general preflight check list. In 
addition to this list, each type of airplane requires its 
own particular list. 

A. Propeller 

1. Inspect blades for pits, cracks, and nicks; in- 
spect hub(s) and attaching parts for defects, 
tightness, and safetying. 

B. Engine 

1. Inspect engine cowling, exhaust stacks, and col- 
lector rings for cracks and security. 

2. Check spark plug tenninal assemblies for clean- 
liness and tightness; check accessible ignition 
wiring and harness for secmity of mounting. 


Figure 42 — The cockpit section of the Link 707 simulator is on exact 
replica of the flight cJeck of the actual aircraft. This photo, taken from 

behind the pilot and co-pilot seots, shows the complete 
of instruments and controls found in the simulator. 

3. Check all bolts and nuts on engine mount. 

certain that the vent openings are clear and the 
tank caps are on tight. 

C. Landing Gear 

1. Inspect tires for defects and proper inflation. 

2. Inspect wheels for cracks and distortion; in- 
spect the brake-actuating mechanism for se- 
curity and cleanliness. 

3. Inspect the landing gear attachment bolts; in- 
spect the struts for proper inflation. 

D. Wings 

1. Inspect the metal or fabric covering for such 
damage as holes, dents and wrinkles; check 
attachment fittings for security. 

2. Check struts and flying wires for security of 
terminal connections; check aileron hinges, 
pins, horns, and tabs. 

3. Inspect all accessible control cables, tubes, and 
pulleys for security. 

E. Empennage 

1. Inspect the covering for damage, the edges for 
dents and distortion, and the fittings for se- 
2. Check struts and brace wires for security of 
terminal connections; inspect control surfaces, 
hinges, pins, horns, and tabs. 

3. Inspect control cables, tubes, and pulleys for 
security and lubrication; check the tail wheel 
assembly for general condition and security. 

F. Fuselage 

1. Inspect the covering for damage and distortion 
and check the windows, windshield, and doors 
for security and cleanliness. 

2. Check all removable cowling, fairing, and in- 
spection plates for security. 

3. Check the control column, rudder pedals, and 
trim mechanism for security of attachment and 
freedom of movement. 

4. Check the proper functioning of the lighting 


system and the location of the spare fuses or 
circuit breakers. 
5. Inspect for security of safety belts and the 
proper functioning of adjustable seats. 
G. Warming Up 

1. See that chocks are under the wheels. 

2. Be certain that the master switch is OFF before 
turning the propeller over by hand; be sure 
that the front is "clear" before using a starter. 

3. Check position of the gasoline shut-off valve, 
carburetor heat control, and carburetor mix- 
ture control. 

4. Test engine(s) on each magneto and on all 
" tanks. 

5. Check radio equipment for proper functioning. 

6. Note oil temperature, pressure and rpm. 

Supersonic Transport 

The newest development in civil aircraft design is 
the supersonic transport, generally spoken of as the 
SST. This could cut flight times at least in half. The 
British and French governments are working jointly 
on an SST, which is expected to be in the Mach 2 
range (1,200-1,400 mph) and available by 1971. It 
is also known that the Russians are working on such 
an aircraft. Both developments are for relatively 
short-range aircraft. 

The United States is planning a longer-range and 
faster SST. Its range is to be about 4,000 miles and 
the speed will be up to Mach 3 (1,800-2,000 mph). 
This is a joint industry-government project and is 
planned for service about 1972. One of the engineering 
developments expected in the SST are wings which 
can be adjusted to the speed desired, thus providing 
lower landing speeds and more efficient lift. 


Aircraft are divided into two classes: (1) heavier- 
than-air and (2) lighter-than-air. Present-day em- 
phasis is on the heavier-than-air craft, particularly the 
airplane. The helicopter, autogiro, omithopter, and 
convertiplane are other types of heavier-than-air craft. 

The major sub-assemblies of the airplane's structure 
are (1) wings, (2) fuselage, (3) tail assembly, (4) 
landing gear, and (5) powerplant. Airplanes having 
one wing are called monoplanes; those with two wings 
are called biplanes. Aerodynamically, monoplanes are 
more efficient. 

The framework or structure of the wings, fuselage, 
and tail surfaces is relatively light because of the kinds 
of metal used, and very strong because of the manner 

in which individual internal members of the structure 
are formed and fabricated. The structure is covered 
with either doped fabric or sheets of very light metal. 

The fuselage houses the crew, controls, cargo, and 
passengers. Occasionally the powerplant and the fuel 
tanks are mounted in the fuselage. The engines in a 
multi-engine plane are mounted on the wings, the 
powerplant supporting members being attached to the 
main spar or spars. Engines and propellers can be of 
the tractor ( pull ) type or of the pusher type. 

The term undercarriage refers to the structure or 
mechanism upon which the airplane rests when it is 
not airborne. In the case of land planes, it consists of 
wheels and struts mounted to the structure to absorb 
the shock of landing. The wheels are equipped with 
brakes to stop the landing roll and to facilitate ground 
handling. The undercarriage may be of the fixed type 
or may be completely retractable. 

The tail assembly consists of vertical and horizontal 
airfoils, both fixed and movable. These surfaces vary 
in size, shape, and arrangement, according to the de- 
sign of the particular make of airplane. The movable 
surfaces are controllable from the cockpit, and in con- 
junction with the ailerons serve to determine the flight 
attitude of the airplane. 

Propellers may have two, three, or four blades. The 
effectiveness of the propeller (which is actually an 
airfoil) is computed from the number of revolutions 
per minute (rpm) and the angle at which the blades 
are set. This angle is called pitch and may be fixed, 
adjustable, controllable, or constant speed. Simple 
wood or metal propellers with no moving parts have 
a fixed pitch. Low pitch means that the blades are 
attacking the air at a relatively flat angle. Low pitch 
is used during takeoff (if the propeller pitch is con- 
trollable ) because greater power is obtained that way. 
High pitch means that the blades are attacking the air 
at a relatively large angle. If the pitch is controllable, 
high pitch is used at cruising speed. 

Airplanes are constructed of materials having light 
weight and great strength. These include the alloys of 
aluminum, steel, and magnesium. In some light planes 
such woods as spruce, fir, and pine are used for struc- 
tural members, and the covering is made of cotton or 
linen fabric which is coated with dope to make it taut 
and weather resistant. The metal parts are joined by 
such techniques as welding, brazing, and riveting, 
while glue is used for fastening together the parts 
made of wood. All aircraft hardware such as bolts and 
nuts is secured by various methods of safetying. 

To insure safety in flight, every airplane must under- 
go regular inspections. Of these, the preflight inspec- 
tion is the most common and is usually performed by 
the pilot. Much more complete inspections are per- 
formed periodically by the airplane mechanic. 



1. Identify the five major components of an air- 
plane and explain the purpose of each. 

2. Briefly describe the construction of a wing, and 
explain the two methods of attaching and brac- 
ing the wings of the fuselage. 

3. Identify the ailerons and the flaps and explain 
the purpose of each. 

4. In what area of the wing are slots located, and 
what is their purpose? 

5. Name and describe the two main types of fu- 
selage construction. 

6. List the major components of the empennage. 

7. Of what value to the pilot are balanced controls 
and servo units? 

8. Explain how the effect of a soft landing is 
achieved by the various types of landing gears. 

9. Differentiate between the tractor and pusher 
types of aircraft. 

10. What types of engines are used to power air- 
planes, and in what positions are they located on 
the airframe? 

11. What are the different types of propellers and 
what advantages are to be derived from chang- 
ing propeller pitch? 

12. Explain the purpose and operation of de-icer 

13. List some of the accessories that make for safer 
and more comfortable flight. 

14. How is forward motion accomplished with a 
helicopter and with an autogiro? 

15. What are the three general types of airships? 

16. What are the two basic types of convertiplanes? 

17. List some of the materials that are used in air- 
plane construction and describe how these mate- 
rials are fastened together. 

18. What is the purpose of safetying aircraft hard- 

Chapter H 

The Aircraft Engine 

Man's failure in his early attempts at flight were due 
primarily to two obstacles: insufficient knowledge of 
the basic principles of aerodynamics and the lack of 
a suitable source of power. The second obstacle was 
the last to be overcome. Several pioneers attempted 
flight using only their own power, but it soon became 
apparent that man was not sufficiently powerful to lift 
and propel himself in flight— with or without the most 
efficient aerodynamic devices. The requirements were 
obvious— an engine must be built which was capable 
of producing considerably more power per unit of 
weight. The solution called for use of lighter, stronger 
materials, new engine design to eliminate unnecessary 
parts and weight, and possibly a new fuel. 

The first partial solution was (juite crude though the 
operating principles of this engine, built by the Wright 
brothers in 1903, are still used in our present recipro- 
cating or piston-type engines. The Wright engine's 
shortcoming was its relatively high weight per horse- 
power. With a weight of about 180 pounds and an 
output of approximately 30 horsepower, it developed 
only 1/6 horsepower per pound. Continued research 
in the use of lighter materials, more powerful fuels, 
the principle of supercharging, and more efficient 
arrangement of cylinders has since increased the ratio 
of horsepower to weight in reciprocating engines to 
appro.ximately one horsepower per pound. When the 
aviation industry demanded a more powerful engine, 
the jet or "reaction" engine was developed. The jet 
engine is capable of producing several horsepower per 
pound of weight at high speeds. 

Aircraft Engine Requirements 

Although the fundamental aircraft engine recjuire- 
ment is still the same as when the Wright brothers 
built their engine— as much power as possible from 
a given weight— the airplane engine may vary accord- 
ing to the purpose for which the plane is intended. 
Some types of engines are more suited to light private 


Figure 43 — Aircraft Engine Cylinder Arranger 


airplanes, others better suited for civilian transports, 
and still others more adapted to military aircraft. 

Regardless of size, type, or principle of operation, 
all aircraft engines possess certain mutual characteris- 
tics. These characteristics are: 

( 1 ) development of a reasonably large amount of 
power for a given weight, 

(2) reliability and performance at various speeds, 

(3) fuel and oil consumption compatible with 
power produced, 

( 4 ) lack of excessive vibration, 

(5) relatively easy maintenance. 

Aircraft Engine Types 

Installation of the engine in the airplane raised 
several new problems including cooling and stream- 
lining. To overcome these problems, wliile fulfilling 
the previously mentioned requirements, manufacturers 
have designed engines with many different cylinder 
arrangements. ( Figure 43. ) One of the first air-cooled 
radial engines was a French rotary type, i.e., the 
cylinders and crankcase revolved around a stationary 
crankshaft. The French rotary type engine had good 
cooling characteristics, but because of excessive vibra- 
tion, it became obsolete. The most commonly used 
engines have their cylinders arranged parallel to each 
other in tandem (in-line), in two tandem rows at ap- 
proximately right angles (V), in two rows on opposite 
sides of the crankshaft (flat or horizontal opposed), or 
like spokes of a wheel around a central shaft ( radial ) . 



Figure 44 — Types of Crankshafts 


Courtesy Wright Aeronautical Corp. 
Figure 45 — Front View of 9-Cylinder Radiol Engine 

Because cooling difficulties more than offset stream- 
lining advantages of the in-line and V-type engines, 
most modern reciprocating engines are horizontally 
opposed or radial. Opposed engines are used in almost 
all light aiiplanes, including small twin-engine planes 
where the engines are "buried" in the wings. The 
number and the size of the cylinders used in opposed 
engines are so limited by cooling problems and crank- 
shaft design that opposed engines rarely exceed 250- 
300 horsepower. Larger airplanes, requiring more 
power, use radial engines— some with two or four rows 
or "banks" of cylinders. Such engines can develop in 
excess of 3,.500 horsepower per engine. When even 
more power is needed, engines are used in pairs, in 
groups of four, or as many as six or eight per plane. 
However, more power per engine requires a different 
type— the jet or rocket. 

Aircraft Engine Parts 

Some knowledge of the parts of an engine is pre- 
requisite to understanding its principles of operation. 
(Figures 44, 45 and 46.) The main function of the 
crankshaft is to change reciprocating motion into 
rotary motion. The force of the expanding gases on 
the top of the piston is transmitted to the crankshaft 
thiough the connecting rod or a link rod. The type of 
crankshaft varies with the engine. A single row radial 
engine uses a crankshaft with one throw or crank, 
about which a master rod is fitted. Link rods connect 
this master rod with all of the cylinders except one— 


Figure 46 — Cutaway View of Twin-Row Radial Engine 

the master rod cylinder. An in-line or opposed engine 
normally uses a crankshaft with as many throws as it 
has cylinders and with a connecting rod between each 
cylinder's piston and its respective crank throw. The 
crankshaft may be connected directly to the propeller, 
or through reduction gears which slow the rotation of 
the propeller relative to the crankshaft. The cylinder 
head is forged or cast aluminum and is threaded and 
then shrunk onto a steel cylinder barrel which has a 
hardened inner wall. The intake valve has a solid 
stem, while the exhaust valve may be hollow and filled 
with metallic sodium to improve the heat transfer to 
the cylinder. Cooling fins on both head and barrel 
aid in keeping cylinders below dangerous tempera- 
tures. Piston rings help prevent loss of gas pressure 
above the piston during compression and power 

The Four-Stroke Cycle Principle 

Reciprocating engines operate by repeating the 
same cycle of events in each cylinder, i.e., (1) a 
charge of fuel and air is forced into the cylinder, 

(2) the charge is compressed, (3) the charge is ig- 
nited, (4) power is obtained from the expanding 
gases, and (5) the burned gases are expelled. The 
first event may differ somewhat in diesel engines or 
in those equipped with direct fuel injection, but, 






Figure 47 — Airplane Engine Cylinder Nomenclatur 

Figure 48— Val 


fundamentally, the same events are present. These 
are sometimes called: (1) intake, (2) compression, 
(3) ignition, (4) power, and (5) exhaust. Most en- 
gines require two complete revolutions of the crank- 
shaft or four strokes (a movement of the piston from 
top dead center to bottom dead center in the cylinder, 
or vice versa, is called a stroke) to complete all five 
events in the cycle. Such engines are called four- 
stroke cycle engines, or sometimes four-cycle engines. 

Two valves, operated by a cam shaft or a cam ring 
and a connecting linkage, are required in each cyl- 
inder to complete this cycle of events. (Figure 47.) 
The gears actuating the valve-operating mechanism 
and the magneto are correctly meshed with those on 
the crankshaft to give correct timing to these events. 
(Figures 48 and 49.) 

In more detail, the five events in a complete cycle 

1. Intake. With the e.xhaust valve closed and the 
intake valve open, the piston moves downward in the 
cylinder, reducing the pressure therein and causing 
air ( and fuel, if a carburetor is used ) to flow through 
the induction system into the cylinder. 

2. Compression. The intake valve closes shortly 
after the piston passes bottom dead center, and the 


^^ ^ ^ ^ ^ 






Figure 49 — Slages of the Four-Slroice Cycle Engine 


Figure 50 — Diogram Showing the Radial Engine Lubricolion Syslen 

fuel and air charge is compressed as the piston moves 
toward top dead center. 

3. Ignition. A high-voltage current flowing from 
the magneto through the distributor at the correct 
instant, usually 20° -30° before top dead center, 
jumps a gap in the spark plug and ignites the fuel 

4. Power. The burning gases create very high pres- 
sures inside the cylinder and after the piston has 
passed top dead center (carried there by momentum 
or the force on other pistons) it is forced down, caus- 
ing the crankshaft to rotate. 

5. Exhaust. When the piston approaches the bot- 
tom of the cylinder, the exhaust valve opens and stays 
open almost three-fourths of a revolution, thus permit- 
ting the burned gases to be forced out by the upward 
travelling piston. 

The complete cycle is repeated appro.ximatcly 1,000 
times by each cylinder during every minute of opera- 
tion. An eighteen cylinder engine gets its power from 
approximately 300 power strokes per second. 

Engine Systems 

Although the engine functions as a complete unit, 
its operation is more easily studied by a breakdown 
into smaller functions, or systems. This breakdown 
would include the lubrication, fuel and induction, 
ignition, and mechanical systems. The mechanical 
system is composed of cylinders, pistons, valves, etc.. 

and has already been discussed in the four-stroke 
cycle principle. The lubrication system, besides per- 
forming the obvious and necessary function of lubri- 
cating the moving parts of the engine, has several 
other responsibilities, e.g., helps to cool the engine, 
provides for a better seal between piston rings and 
cylinder walls, prevents corrosion, and actuates hy- 
drauhc units such as valve lifters and propeller con- 
trols. (Figure 50.) Aircraft engines use a pressure 
lubrication system in which oil is pumped through 
drilled passages to the many engine parts which re- 
quire lubrication. Other parts, such as cylinder walls, 
piston pins, and some roller or ball bearings, receive 
oil by splash and spray. The oil supply may be car- 
ried either in the engine's crankcase (wet-sump) or 
in an external tank (dry-sump). Most opposed-type 
enj^nes are the wet-sump variety, but radial engines 
are always dry-sump. The dry-sump engine is so 
called because the oil which settles into the sump 
(collection place) is pumped back to the external 
tank as quickly as possible by a scavenging pump. 
If the external tank is very large, as in a large airliner, 
a small hopper tank within the main supply tank re- 
ceives the oil pumped from the engine by the scav- 
enger pump for recirculation within the engine. When 
the supply of oil in the hopper tank drops below the 
level of that in the main tank, additional oil is added 
from the main supply. Several benefits derive from 
the use of a hopper tank, the most important being a 
more rapid warm-up of the engine. 



Internal combustion engines must be supplied with 
the correct mixture of fuel and air, which is taken into 
the cylinders, compressed, ignited, and burned to sup- 
ply power. This process may be accomplished by use 
of a fuel injection system which includes an air- 
metering device, or a carburetor, in which air and fuel 
are properly mixed before entering the intake mani- 
fold and cylinders. (Figure 51.) 

The carburetor must be able to provide the proper 
mixture (about one part of fuel to fifteen parts of air, 
by weight) at all speeds. The correct mixture requires: 
( 1 ) an idling system when the throttle is almost 
closed; (2) a main metering system for all other throt- 
tle positions; (3) an accelerating system to prevent 
temporary lean mixtures upon rapid acceleration; 
(4) an economizer system to supply extra fuel at 
higher engine speeds; and (5) a mixture control to 
allow for different air densities. 

The throttle controls air flow through a restriction 
or venturi, in which a fuel discharge nozzle is placed. 
Increased air velocity causes a pressure drop, and 
fuel then flows from the discharge nozzle into the 
air stream. A wider throttle opening permits faster 
air flow and more fuel to be discharged. 

Fuel must be vaporized and mixed with the oxygen 
in the air before it can burn. .As fuel vaporization 

occurs, the mixture's temperature drops, sometimes 
as much as 60° F. Water vapor in the air may be 
condensed and frozen, even when outside air tem- 
peratures are as high as 80° F. Ice may collect on 
the butterfly valve (throttle) of the carburetor or 
in the intake manifold and, if allowed to build up, 
will cause engine stoppage. Carburetor ice is usually 
prevented by a carburetor air heater, which sends air, 
heated by the exhaust stacks, through the carburetor. 
Excessive use of the carburetor air heater may cause 
loss of power, or detonation; consequently carburetor 
heat should be used only when required. 

At higher altitudes, the difference in pressure be- 
tween the inside of the cylinder on the intake stroke 
and the outside atmosphere may be so small that 
air and fuel flow into the engine are greatly reduced 
without some help. Full fuel and air flow are restored 
by a supercharger; in fact, the density of the intake 
charge may be increased to more than twice that 
obtained by an unsupercharged engine at sea level. 
The supercharger is a centrifugal pump which forces 
more air-fuel mixture into the cylinders. It may be 
internal, driven by a gear train connected to the crank- 
shaft, or external, driven by the exhaust. The external 
type is called a tiirbosupcrchargcr. (Figure 52.) Most 
of the larger radial engines have internal or integral 
superchargers, which have the additional responsi- 






Figure 51 — A t/pical aircraft fuel system showing how the gasolii 
pumped from the fuel tank into the carburetor float chamber, d 

out of the main jet by suction, and, in an atomized or vaporized form, 
flows inside the intake manifold to the intake valve of the cylinder. 


bility of providing an even distribution of fuel to all 
of the cylinders. 


The compressed fuel-air mixture is ignited in the 
cylinder, at the correct time, by a spark from a spark 
phig. (Figure 53.) The spark is caused by a high- 
voltage current developed by a magneto. ( Figure 54. ) 
As the permanent magnet rotates, a fluctuating mag- 
netic field is developed in the pole shoes, around which 
both the primary and secondary coils are wound. The 
changt in magnetic field creates a low-voltage current 
in the primary circuit, which includes, besides a coil 
with a relatively few turns of fairly heavy wire, a 
condenser, a switch, and a set of breaker points. The 
primary circuit is interrupted by the breaker points 
aided by the condenser at the most opportune time 
to cause a very rapid collapse in the magnetic field 
through the pole shoes. As a result, a high-voltage cur- 
rent is induced in the secondary circuit, which in- 
cludes, besides a coil with many turns of fine wire, 
the distributor, ignition leads, and spark plugs. The 
distributor causes current to flow to the spark plugs 
in the correct sequence, or firing order. An aircraft 
engine usually has two complete ignition systems, with 
two magnetos and distributors and two complete sets 


Figure 53 — A Simplified Cutaway Drawing of a Spark Plug 

of spark plugs, not only for better ignition, but also 
as a safety factor. 


Accessories include those items which aid an en- 
gine's operation, but do not necessarily cause it to 
function. All large engines, and many smaller ones, 
are equipped with electric starters which are usually 
powered by a storage battery. A second accessory, the 
generator, is required to recharge the battery that also 
provides power for lights, flap and landing gear actu- 
ating motors, radio equipment, etc. Other accessories 
found on many engines include vacuum pumps for 
operating certain instruments, and propeller governors 
which control propeller blade pitch to maintain a con- 
stant engine speed through wide variations in throttle 



Figure 52 — Culawoy View of o Turbo Supercharger 

Figure 54 — Schematic Diagram of an Aircraft Engine Magneto 


Power Factors 

Fundamentally, an internal combustion engine 
changes heat energy into mechanical energy and its 
power depends upon the rate at which it can do 
work. Three factors are involved in power devel- 
opment, (1) engine size or piston displacement, 
(2) speed of rotation, and (3) the amount of pres- 
sure on the piston. 


The horsepower formula is: H. P. = . "P" 


is the effective pressure on the piston measured in 
pounds per square inch. "L" is the distance, measured 
in feet, which the piston moves from top dead center 
to bottom dead center (stroke). "A" is the cross- 
sectional area of the cylinder in square inches. "N" 
is the number of power strokes which the engine has 
in one minute. The constant divisor of 33,000 is used 
because one horsepower is defined as that power 
required to perform 33,000 foot pounds of work in 
one minute. 

For example, a nine-cylinder engine with a 6-inch 
Cylinder diameter (bore), a 6-inch stroke, turning at 
2200 rpm with a mean effective pressure of 160 pounds 
per square inch will develop horsepower at the rate of 
160 X 1/2 X 32 X 3.1416 X 9900 
or about 680 horsepower. Everything in the substitu- 
tion should be obvious with the possible exception 
of the value of "N", which was 9900. This value is 
obtained from the fact that in two complete revolu- 
tions of the crankshaft of any four-stroke cycle engine, 
each of the cylinders should deliver one power stroke. 
Therefore, a nine-cylinder engine rotating 2200 times 


per minute should have 9 X or 9900 power 


strokes in one minute. 

Modern Powerplants 

Jet and rocket propulsion devices are often called 
reaction engines because their thrust is produced as a 
result of a reaction to an action. Perhaps the best 
explanation of the effect is a comparison with a more 
familiar occurrence, propulsion by a propeller driven 

Figure 55 shows a typical engine nacelle and pro- 
peller. Anyone who has been behind such an engine 
when it is operating knows that a large amount of air 
is being pushed to the rear with a high velocity. 
According to Newton's third law, for every action 
there is an equal and opposite reaction. In this in- 
stance, a force is being produced on the propeller 

Figure 55 — Typical Reciprocating Engine-Propeller Combination 

and engine combination in the opposite direction from 
that in which air is being thrown by the propeller. 
This combination might be called a "reaction engine." 
Figure 56 shows the same items as above, except 
they have been enclosed in a tube, and the air- 
flow is directed to the rear through this tube. 



56 — Reciprocating Engine-Propeller Combination Enclosed 


In figure 57 the engine-propeller combination has 
been replaced by a turbine wheel at the rear, a com- 
pressor at the front, and combustion chambers in 
which fuel and air are burned between the two. This 
combination causes air flow through the tube in the 
same manner as the engine-propeller combination in 
Figure 56. The mass of air being moved in this 
arrangement may be less but the final velocity of the 
moving gas is much greater and the resultant tlirust 
can be much greater. This thrust is the reaction, which 
was caused by the action of air moving toward the 
rear, and is transmitted from the component parts of 
the engine through its frame to the aircraft. 



Figure 57 — Compressor-Turbine 
(Typical Turbojet Engine) 


The same result-a high-velocity flow of gases— is 
accomplished in the engine shown in figure 58 by 
burning fuel inside a container which is open at only 
one end. Such a device is called a rocket. 

Thrust is NOT the reaction of the e.xpelled gases 
upon the air outside the engine. Thrust would be the 
same if the gases were being expelled into a vacuum. 
Thrust depends upon: (1) the mass of gas being 
moved, and (2) the velocity with which it is expelled 
from the exhaust or tail pipe. Technically, the second 
factor is the change in the velocity of the entering 
and leaving gases, but it is sufficient for our purpose 

to consider only final velocity. The mass of gas being 
moved is increased by forcing as much air as possible 
into the inlet section of the engine. The velocity is 
increased by heating and expanding the air and by 
burning the fuel which has been mi.xed with it, then 
expelling it through a restricted exhaust passage. 

Three types of jet engines may be considered, al- 
though only one merits much discussion at present. 
The most simple of the jet engines is the ram jet, or 
athodijd (a contraction of aero thermodynamic duct). 
( Figure 59. ) It is often called a "flying stovepipe" be- 
cause it consists of a tube into which fuel is injected, 
burned, and then the hot gases expelled from the tail 
pipe. The "catch" is that the air which enters this jet 
must be compressed by the ramming action of the 
device itself. Consequently, it wOl not operate until 
it has reached a very high velocity— at least 500-600 
miles per hour. It can be used to power helicopter 
rotors, as an auxiliary powerplant in an aircraft which 
has another engine to bring the aircraft up to the 
required speed, or in some other limited applications. 




Figure 59 — Schematic Diagram of a Rom Jet Engine 

The pulse jet (Figure 60) is almost as simple as the 
ram jet, except for the addition of automatic shutters 
in the inlet section. These shutters open as the engine 
moves through the air thus permitting air to enter 
the inlet opening. The shutters close when fuel, which 
has been injected into the same section, bums and 
causes the air to heat and expand. The heated gases 

Figure 58 — Simple Rocket Engine 

Figure 60 — Schematic Diagram of o Pulse Jet Engine 


Figure 61 — Cutaway View of a Turbojet Engine 

are then forced out the rear at high velocity. The drop 
in pressure, as the gases leave the exhaust section, 
again forces open the shutters, and the same cycle is 
repeated as often as 50-60 times per second. Although 
the pulse jet is simple to build, it loses efficiency at 
high speeds and is exceptionally noisy. There have 
been some military applications of this engine, notably 
the German "buzz bomb" of World War II, but its 
disadvantages are such as practically to eliminate it 
from commercial use. 

The third, and by far most important commercially, 
is the turbojet. This classification is sometimes further 
subdivided into ( 1 ) the pure jet engine, without a 
propeller (Figure 61), and (2) the turboprop engine, 
which incorporates a propeller driven by the main 
shaft through a reduction gear train. 

Turbojets are also classified according to the type 
of compressor used. Earlier models invariably used a 
compressor similar to the centrifugal pump of the 

turbo supercharger and were called centrifugal flow 
engines. Because considerable energy was expended 
to change the direction of airflow as it was being com- 
pressed, the centrifugal pump was later replaced by 
a device similar to a turbine wheel in the turbo super- 
charger. This engine was called axial flow and per- 
mitted air to flow in more of a straight line during its 

Regardless of type or manufacturer, turbojet en- 
gines consist, primarily, of four sections. These sec- 
tions are: (1) compression, (2) combustion, (3) tur- 
bine, and (4) exhaust. The turbine lies directly behind 
the combustion section, and is driven by the gases 
leaving the combustion chamber. The shaft, which 
the turbine turns, also supports the compressor which 
compresses the incoming air before it enters the com- 
bustion chambers. Fuel is injected into the combus- 
tion section by a spray nozzle and burned. Ignition is 
continuous, and spark plugs or ignitors are required 

Figure 62 — Gas Generator Section of a Turbofon Engine 


only for starting the engine. After the heated gas 
passes the turbine section, it flows through the ex- 
haust cone to the atmosphere, increasing in velocity 
and decreasing in pressure until it leaves the cone. 
In addition to the basic units of the turbojet engine, 
numerous appliances and accessories are required. 
These include fuel pumps, pressure regulators, oil 
pressure and scavenger pumps, a starter, a generator, 
and an ignition system. Some accessories have a more 
demanding job to perform than their reciprocating 
engine counterparts; e.g., fuel pumps (there are usu- 
ally two per engine ) must be able to develop pressure 
twenty to fift\' times that of the normal fuel pump of 
a reciprocating engine. The pressure regulators must 
be able to control fuel flow in widely varying condi- 
tions of atmospheric temperature and pressure. The 
starter must be able to accelerate the compressor, 
turbine and shaft from zero to 2000 or 3000 rpm in 
a very few seconds. The electric starter requires about 
1,200 amperes of current during this period; however, 
larger jet engines often use a small gas turbine engine 
as a starter. There may also be other minor accessories, 
such as vacuum pumps, electric motors to move con- 
trollable vanes in the inlet or exhaust sections, etc. 


The first turbojets used centrifugal-flow compres- 
sors. (Figure 63.) The centrifugal-flow compressor is 

easy to build and maintain, but rather inefficient be- 
cause the airflow direction is changed so often during 
its passage through the engine; e.g., this compressor 
is usually double sided, and consequently the air 
entering the rear inlet must traverse a complete circle 
before it enters the combustion chamber. The maxi- 
mum compression ratio obtainable with centrifugal- 
flow compressors is only about 3 to 1. 

More recently developed turbojets, and almost all 
of the turboprop engines, use an axial-flow com- 
pressor. ( Figure 64. ) This compressor has several 
rows of compressor blades set into a rotating drum 
and separated by rows of somewhat similar blades in 
a fixed outer case called stators. The rotating blades 
(actually airfoils) force the air toward the rear with 
the stators serving as guide vanes to direct the air to 
the next row of blades. An engine with twelve rows of 
rotating blades has thirteen rows of stators and is 
called a twelve-stage compressor. The entire compres- 
sor is driven by one turbine wheel. This type of com- 
pressor can compress incoming air by as much as a 5 
to 1 ratio. When higher compression ratios are desired, 
a split compressor, consisting of two different com- 
pressor sections, each with a row of rotors on its shaft, 
and separate turbines on the opposite ends of the 
shafts, may be used. Sometimes two or more stages of 
turbines are used to drive the compressor in the high 
compression section. Split compressors can achieve 
compression ratios as high as 12 to 1. 

Figure 63 — Cutaway View of a Centrifugol Flow Compressor Eng 



Only a small part of the compressed air mixes with 
fuel and burns as it travels through the engine, al- 
though all of it is heated. A cannular combustion 
chamber has an inner and an outer liner, and as air 
leaves the compression section some flows between 
these liners while the rest enters the inner chamber 
where it mixes with fuel supplied by the fuel nozzle 
in the front of this chamber. The spray is controlled 
in such a way that the burning is concentrated near 
the center of the inner liner in order to prevent the 
burning of the metal. Thus, a layer of air separates 
the burning mixture from the inner liner. Since com- 
bustion chambers are connected by cross-ignition 
tubes, only two igniters are needed and then only for 
starting. As many as twelve to fourteen combustion 
chambers may be used in the average turbojet engine. 


Turbine assemblies are quite similar in design and 
construction. The most critical stresses occur in this 
section because turbine blades or buckets must 
withstand high temperatures (sometimes as high as 
1500° F. ) and centrifugal forces. Clearances ate very 
critical, and, because of expansion at high tempera- 
tures, will vary with the change in temperature. Cool- 
ing the turbine wheel and lubricating the bearings are 
major problems. The first is usually solved by ducting 
air from the compressor section to the turbine, and the 
second by using a special type of lubricant. 

The biggest di£Ference between turbojet and turbo- 
prop engines (aside from the additional propeller and 
gear box in the turboprop) is in the turbine section. 
One turbine wheel, with its outer rim of buckets, is 
normally sufficient to drive several rows of compressor 
blades. However, if the main shaft must also turn a 
propeller, more rows of turbines are needed. Whether 
one or more turbines are used, a row of stationary 
blades is placed in front of each turbine to direct the 
gas flow toward the buckets at the correct angle. This 
particular row of stator blades is called a nozzle 


The efficiency of a turbojet is increased by properly 
controlling the hot exhaust gases. The exhaust cone or 
nozzle may be convergent, divergent, or both, although 
the increased velocity of the convergent type is de- 
sired. Some engines use a variable cone which can be 
changed to get maximum efficiency. A thrust aug- 
menter, called an afterburner, is often used in military 
turbo jets. In effect, the afterburner becomes a ram 
jet engine which receives the compressed gas at its 

Figure 64 — Axial Flow Compressor of Turbojet Power Unit 

inlet and into which fuel is then discharged. Such a 
combination is often called a turboramjet. Since the 
gas is already aflame as it enters the afterburner, it 
continues to burn and the exhaust velocity is thereby 
greatly increased with only a slight increase in over-all 
engine weight. Fuel consumption is somewhat in- 
creased in proportion to thrust gained, but the increase 
in thrust per pound of weight, including both engine 
and fuel, is more than sufficient to warrant use of the 
afterburner when maximum performance is required. 


It is possible to calculate the power which a re- 
ciprocating engine will develop when its piston dis- 
placement, rpm, and mean eflFective pressures are 
known, and to test this calculation with a Prony 
brake. For a jet engine, however, only thrust can 
be ascertained until the forward speed factor is 
added. Since work is defined as force times dis- 
tance (W = FxD) and power is work per unit of time, 

force X distance. 

then power = -. 


A jet engine developing 5,000 pounds of thrust 
tends to push itself, and the aircraft in which it is 
mounted, forward with that thrust. However, if the 
airplane is not moving, the force of 5,000 pounds 
multiplied by a distance of zero gives a product of 
zero foot-pounds of work and zero power. The same 
thrust, while pushing the airplane forward at a speed 
of 240 miles per hour (or 352 feet per second) is 
performing work at the rate of 5,000 x 352 X 60 foot- 
pounds per minute. Dividing this by 33,000, the num- 


ber of foot-pounds per minute required for one horse- 
power, gives 3200 horsepower. The same thrust at a 
higher speed means more power. Thus at a speed 
of 375 mph., the amount of horsepower developed by 
a jet engine is numerically equivalent to its thrust. 
For example a 5000 pound thrust engine develops 
5000 H.P. at 375 mph. since 

5000 X 375 X 5280 

60 X 33,000 = ^°^^- 


The low efficiency of a turbojet engine at low 
altitudes and low speeds is a major deterrent to its 
use for other than long range aircraft. As a com- 
promise between the turbojet and the reciprocating 
engine— propeller combination, the turboprop engine 
was developed. In the turboprop engine, a major 
part of the energy in the gases emerging from the 
combustion chambers is tranformed into mechan- 
ical energy in the rotating shaft. A propeller is con- 
nected to the shaft by reduction gears, so most of 
the tlirust developed by the turbine engine is utilized 
through the propeller. A considerable increase in 
efficiency at low altitudes and low speeds is thus 
obtained through the use of the turboprop. How- 
ever, a possible shortcoming still exists with the use 
of the propeller— that of poor efficiency when its 
rotational speed is too great. Most of the more power- 
ful reciprocating engines use propeller reduction gears 
to prevent the prop tip speeds from becoming super- 
sonic, at which point the developing shock waves 
cause loss of propeller efficiency. 

The turbofan engine is a modification of the stand- 
ard turbojet engine. It can produce more thrust by 
expelhng a greater volume and weight of cooler gas. 
Through its large intake the turbofan pulls in four 
times as much air as the standard turbine engine. 
This gives a greater volume of gases expelled at 
lower velocity and temperature, thus producing in- 
creased thrust at a lower noise level. The turbofan 
engine has one or more rows of compressor blades 
extended several inches beyond their normal length 
to direct air back through an area which surrounds 
the regular engine giving what is called a forivard- 


Figur* 65 — Rocket Power Unit 

fan engine. The fan acts quite similar to an ordinary 
propeller. An alternative procedure is to extend one 
or more of the rows of turbine blades, resulting in 
an aft-fan engine. With a fan, there is a sufficient 
increase in thrust and efficiency to propel an airplane 
faster than the speed of sound without using an 

A more recent development, one which engineers 
are expecting to utilize in the engines of supersonic 
airliners designed to travel at speeds of Mach 3 or 
above, is the fan burner. Similar in operation to the 
afterburner of the normal turbojet engine, the fan 
burner engine obtains additional thrust by burning 
additional fuel in the fan duct. Thrust can be doubled 
with a fan burner, and in addition, these engines 
have lower operating temperatures, a wider range of 
available power, and a much lower weight per horse- 
power. In fact, the fan burner engine has proved to 
be very efficient and economical at low altitudes and 
speed without burning in the fan stream, and at 
high altitudes and speeds with burning in the fan 
stream. The high-thrust turboramjet has apparently 
been far surpassed in thrust as well as economy by 
the fan burner engine. 

Recent military successes in the field of rocket pro- 
pulsion have raised hopes and predictions of ex- 
tremely rapid intercontinental travel, and even inter- 
planetary travel. While it is true that rockets can be 
and have been developed which can deliver tremen- 
dous thrust, there are still many unsolved problems 
delaying wide acceptance of this method of propulsion 
for anything other than military projectiles. This does 
not rule out the use of rockets as auxiliary power for 
takeoff or emergency purposes for some manned air- 
craft, and for satellites of the earth, sun, moon, or 
some other planetary body. ( See Chapter 12. ) 

A major problem at present is fuel consumption. 
Whether the fuel be liquid or solid, rockets must still 
carry their own oxygen supply, thereby increasing fuel 
load weight and decreasing pay load weight. Rocket 
power is successful when the vehicle it powers can 
attain very high speeds and high altitudes. Both of 
these conditions have physiological implications which 
are serious. 

Another difficult problem involves control of a 
rocket-powered aircraft while in flight. If the flight is 
made at sufficient altitude to warrant use of rocket 
propulsion, aerodynamic controls will be almost use- 
less. If the rocket leaves the low heavier layer of 
atmosphere and progresses to a high speed in the thin 
upper layer, the re-entry into the lower altitudes with 
its resultant friction and heat also causes trouble. 


The military implications of rocket propulsion are 
awesome and frightening, particularly when coupled 
with electronics s\'stems which permit remote or 
automatic contiol of various "stages" of the composite 
rocket, and with intricate and remarkably accurate 
guidance systems. A schematic drawing of the essen- 
tial parts of a rocket appears in figure 65. 


The success of the atomic-powered submarine has 
led to a clamor for an airplane powered by an atomic 
engine; in fact, the Hight of such a plane by another 
government has been reported. Although the report 
may be premature, the possibility of such an engine 
cannot be denied. Basically, the engine would develop 
thrust using the same principle as the jet, with the 
atomic reactor providing the heat normally obtained 
in the combustion chambers of the conventional jet. 
Major problems, including lack of protection from 
radiation of the atomic materials, have delayed devel- 
opment of this engine. Quite possibly, its principal 
application may be that of an auxiliary engine— to be 
used only when the airplane has reached high speed 
and altitude by use of another type engine. Inter- 
planetary travel may become a reality if and when 
the atomic engine is perfected. 


Early powerplants were unsuitable for aircraft be- 
cause they were heavy, cumbersome, and unable to 

deliver sufficient horsepower. First aircraft engines 
were crude and inefficient, but had the same operating 
principle of present-day reciprocating engines. 

To be satisfactory for aircraft use, an engine must 
be powerful, compact, and light in weight. Fuel and 
oil consumption must be within reason, and main- 
tenance must be relatively easy. 

Almost all current reciprocating aircraft engines are 
air-cooled and either of the radial or horizontally- 
opposed type. 

Practically all aircraft engines operate on the four- 
stroke cycle principle. There are five events in each 
cycle: intake, compression, ignition, power and 

The main functions of the lubrication system are 
to (1) lubricate, or reduce friction, (2) cool the 
engine, and (3) give a better seal between piston 
rings and the cylinder wall. 

The carburetor acts as a control and mixing cham- 
ber for liquid gasoline and air. Gasoline is atomized 
and vaporized in the induction pipes and cylinders. 
The fuel charge is ignited at the proper instant by a 
spark plug which receives high voltage current from 
the magneto via the distributor and ignition leads. 

Reaction engines, such as the ram jet, pulse jet, 
turbojet, turboprop, and rocket devices, produce 
thrust by expelhng gases through a jet or nozzle. Jet 
engines use oxygen from the earth's atmosphere but 
rockets carry their own oxygen, enabling them to 
produce thrust outside the atmosphere. 


1. Why are the most liigh-powered reciprocating 
engines of the multi-row radial type? 

2. Name the five events in a complete cycle in a 
four-stroke cycle engine. 

3. How many power strokes should be delivered 
per minute by a nine-cylinder engine operating 
at 2200 R. P. M.? 

4. What is to be substituted for each of the letters, 
P, L, A, and N in the horsepower formula? What 
does the 33,000 in the denominator represent? 

5. What is the function of a carburetor in a recip- 
rocating engine? How is carburetor icing elim- 
inated or prevented? 

6. What are the two main functions of the lubrica- 
tion system? 

7. What causes high-voltage current to be induced 
in the secondary circuit of a magneto? 

8. Under what operating conditions is a super- 
charger required? Why? 

9. Name four different kinds of jet engines. 

10. What is an afterburner, and what is its purpose? 

11. What advantages does a turboprop engine have 
over a turbojet engine? 

12. What is the purpose of the turbine in a turbo- 
jet? In a prop jet? 

Why is a spht compressor used in high perform- 
ance jet engines? 

Why is the turbofan engine superior to other 
types of jet engines? 

Where is the "fan" located in the turbofan 





Chapter 6 Airplane Instruments 

Due to the inability of the human senses to cope 
completely with variable climatic conditions and com- 
plicated mechanical devices, it is essential that certain 
physical characteristics of the airplane be measured 
and indicated. These measured indications must be 
extremely accurate and readily accessible to the pilot. 
Safe, economical, and reliable operation of modern 
aircraft and their powerplants is absolutely dependent 
upon the proper use of instrmnents. 

Instruments are divided into three classes: (1) flight 
instruments; (2) navigation instruments; and (3) en- 
gine instruments. The number of instruments found in 
various aircraft depends upon the size of the aircraft, 
and upon the purpose for which the aircraft is used. 
Multi-engine aircraft, for example, require a separate 
set of instruments for each engine and often require 
a duplicate set of instruments for the second pilot or 
the flight engineer. 

In addition, the wide variety of aircraft operational 
temperatures, pressures, and speeds make it necessary 
to paint operational markings in various colors on the 
cover glasses or faces of the instnnnents. Short radial 
lines and arcs of circles indicate the safe operating 
limits prescribed by the manufacturer for a particular 
engine or aircraft. 

The Federal Aviation Agency (FAA) also has re- 
quirements that must be met for certain conditions 
of flight operation, e.g., visual flight rules (VFR), 
instrument flight rules (IFR), and day and night op- 
eration. These FAA requirements also govern the 
number and kind of instruments to be found in a 
specific airplane. 

Some of the more important instruments found in 
airplane cockpits are the airspeed indicator, altimeter, 
rate of climb indicator, compass, tachometer, oil pres- 
sure gage, oil temperature gage, turn and bank indi- 
cator, directional gyro, and gyro horizon. Before 
describing their operation and functions, it is neces- 
sary to discuss two other fundamental aircraft acces- 
sories which are part of the instrument system, i.e., 
the pitot-static tube and the venturi tube. 

Pitot-Static Tube 

The airplane's pitot-static tube (Figure 66) fur- 
nishes accurate measurements of (1) impact (pitot) 
and (2) static pressures. The pitot-static tube is com- 
posed of two separate tubes of seamless brass tubing 
mounted together in a housing or head. Specifically, 
the pitot-static tube is used to supply impact pressure 
to the sensitive element in the airspeed indicator and 
to maintain static pressure inside the housing of the 
aii-speed indicator, altimeter, and rate of climb instru- 
ment. The pitot-static tube is positioned on the air- 
plane so that its axis is parallel to the longitudinal 
axis of the airplane. It is attached to the airplane in 
a location that is away from the propeller's slipstream 
and in undisturbed air. 

The pitot tube is open on the front so that it is sub- 
jected to the full impact of the air pressure which is 
created by the forward motion of the airplane. The 
static tube, however, is closed on the front end with 
holes drilled into its sides, top, and bottom in order to 
subject it to the pressure of the static or still air. 

The pitot and static pressures obtained from these 
tubes are transmitted to the cockpit instruments by 
air-tight tubing. The instrument connection points for 
this tubing are always marked with "P" for pitot pres- 
sure and "S" for static pressure, to make easy, sure 

lube solder cone - 

Tube nu+ -' 

Solder cone nut - ' 


Figure 64 — Standard PitolStolic Tube. 1. Solder Cone Nut; 
Nut; 3. Tube Solder Cone. 


Figure 67 — Venturl Tube 

mechanical connections. Water, snow, ice, or other 
foreign matter which enters the pitot tube results in 
either restriction or complete stoppage of the air flow. 
Stoppage, of course, causes either inaccurate readings 
or complete operational failure of the airspeed indi- 
cator instrument. 

Venturi Tube 

The airplane's ventiu-i tube (Figure 67) develops 
suction or lower than normal atmospheric sea-level 
pressure. This suction operates vacuum-driven instru- 
ments on those aircraft which do not have engine- 
driven vacuum pumps. 

Although the hollow venturi tube flares out on both 
ends, it has a restriction in the "throat" of the tube. 
When air passes through the throat of the tube, the 
velocity of the air increases, thereby causing a de- 
crease in the air pressure. A tube connected to this 
restiicted portion of the venturi then develops a pres- 
sure which is lower than the normal atmospheric sea- 
level pressure. A four-inch venturi, for example, causes 
a three-pound-per-square-inch drop in pressure, i.e., to 
11.7 psi. Vacuum or suction is measured by an instru- 
ment which is calibrated in inches of mercury. Each 
inch of mercury weighs .49 lbs. per inch. 

Venturi tubes, like pitot tubes, are mounted outside 
the airplane and freeze or restrict when subjected to 
ice and snow; therefore, an engine-driven vacuum 
pump is usually considered more dependable. 

The Airspeed Indicator 

The airspeed indicator is a flight instrument which 
aids in ( 1 ) determining the best climbing and gliding 
angles, (2) selecting the most satisfactory power set- 
tings for efficient flying speeds, and (3) maintaining 

200 V 

Figure 68 — The Pilot-Static Tube Showing the Connections to the Air- 
speed Indicator 

the speed of the airplane within its safe operating 

The aiispeed indicator is composed of an air-tight 
case and a sensitive diaphragm capsule. The air-tight 
case is connected to the static tube, which keeps it at 
existing atmospheric pressure at all times. The dia- 
phragm capsule is connected to the pitot tube. As the 
airplane moves through the air, the pitot pressure 
causes the diaphragm to expand with an increase in 
speed and to contract with a decrease in speed. The 
difference between pitot pressures in the diaphragm 
and static pressures in the air-tight case operates a 
series of gears and levers which visually show the 
indicated airspeed (IAS), either in statute miles per 
hour or nautical miles (knots) per hour, on the face 
of the dial. ( Figure 68. ) 

The dial shows the indicated airspeed at which the 
airplane is moving through the air. This indicated 
airspeed is always different from true ground speed, 


except in still air at noniial sea-level atmospheric 
pressure. The pilot, however, is always able to calcu- 
late his ground speed from his indicated airspeed if 
he knows both the altitude at which he is flying, the 
temperature at that altitude, and the direction and 
speed of the wind. As the airplane gains altitude, the 
air becomes less dense and creates a lower atmos- 
pheric pressure. This lower atmospheric pressure af- 
fects the accuracy of the airspeed instrument, thereby 
necessitating the use of a correction factor to recalcu- 
late the true airspeed (TAS)— 2 per cent for each 1000 
feet of altitude, i.e., for each 1000 feet of altitude, the 
airplane actually travels 2 per cent faster than the 
airspeed indicator reads. For example, at 5000 feet of 
altitude the airspeed indicator reads 150 mph. Apply- 
ing the correction factor: 

TAS = 150 mph + (2% X 5000 ft. x 150 mph) 

TAS = 150 mph -h (.02 X 5 X 150) 

TAS = 150 mph + 15 mph 

TAS = 165 mph 
It must also be borne in mind that if an airplane is 
flying at 100 mph. True Indicated Air Speed (TIAS) 
into a 20-mph headwind, the actual speed with respect 
to the ground (GS) would be only 80 mph. (See 
definition of Calibrated Air Speed in Appendix.) 

The reliability of the airspeed indicator is de- 
pendent upon ( 1 ) the pressures delivered to the air- 
speed indicator's mechanism by the pitot-static tube, 
and (2) the accurate response of this mechanism to 
the pitot-static tube pressures. 

The Altimeter 

The altimeter, a flight instrument, has two specific 

1. To measine the elevation of the aircraft above 
any given point on the ground regardless of that 
point's elevation above sea level. This altitude meas- 
urement method is called the "Field Elevation Pres- 
sure" system and represents the field elevation baro- 
metric pressure at a point which is 10 feet above the 
average elevation of the airport's runways. 

2. To measure the altitude of the airplane above 
sea level. This altitude measurement method is called 
the "Altimeter Setting" system and represents atmos- 
pheric pressure, in inches of mercury, at normal sea- 
level pressures. Thus, the altimeter— an aneroid barom- 
eter— (Figure 69) is a sensitive instrument, calibrated 
in feet of altitude instead of inches of mercury, which 
measures atmospheric pressure. 

The aneroid is either a sealed diaphragm capsule or 
a metal cell enclosed in an airtight case which is con- 
nected to the static tube. Atmospheric pressures from 

the static tube act on the capsule by either compress- 
ing or expanding the diaphragm. The movements of 
the diaphragm are then transferred, through a system 
of levers and gears, to indicating hands on the face 
of the altimeter. As the airplane's altitude increases, 
atmospheric pressure decreases and allows the sealed 
diaphragm to expand. The amount of expansion con- 
trols the hands on the face of the altimeter. As the 
airplane descends, however, the increase in atmos- 
pheric pressure causes the diaphragm to contract and 
indicates a decrease in altitude. Atmospheric pressures 

Figure 69 — Altimeter 

constantly change and whenever a change in pressures 
occurs the altimeter hands move— even when the air- 
plane is in a stationary position on the ground. 

Because of the changing barometric pressure, the 
altimeter fails to indicate the correct height unless 
other means are provided to keep it accurate, such as 
a knob on the front of the instrument. If a pilot, flying 
locally, wants to know his height above that particular 
airport, he sets the dial hands, before takeoff, to read 
"zero." After takeoff, the altimeter indicates his alti- 
tude only above that airport. The above description is 
an example of how the Field Elevation Pressure sys- 
tem is used to indicate altitude. 

If a pilot is flying cross-country, he uses the Altim- 
eter Setting system because he must know his specific 
height above sea level. All map elevations are given 
in terms of height above sea level. Prior to takeoff the 
pilot will set his altimeter, by means of the knob, at 
the surveyed elevation of his departure airport rather 
than on zero. On this setting the reading on the 
barometric scale will be the local pressure corrected 
to sea level barometric pressure. After takeoff, the 
altimeter indicates the airplane's altitude above sea 
level rather than the altitude above the surveyed 
airport's elevation. 


Rate of Climb Indicator 

The rate of climb indicator, a flight instrument, is 
also called a vertical sp>eed indicator and is used to 
show either a gain or a loss of altitude regardless of 
the atitude of the aircraft. Specifically, it is used ( 1 ) 
to show rate of ascent or descent, (2) to accomplish 
banked turns without gain or loss of altitude, and 
(3) to establish constant and definite rates of descent 
when making instrument landings. 

The rate of climb instrument (Figure 70) also con- 
sists of a metal diaphragm enclosed in an airtight case. 
The diaphragm is connected to the static tube and the 
air-tight case is sealed except for a small, calibrated 
leak which leads to the internally-connected static 
line. The capsule— diaphragm— is subject to the ascend- 
ing and descending pressure changes. To measure this 
rate of change in atmospheric pressure, the dial hands 
indicate a rate of change in feet per minute. The static 

Figure 70 — Vertical Speed Indicator 

pressure inside the capsule or diaphragm changes 
faster than the air pressure inside the case because the 
small-size hole in the case permits a calibrated leak. 
Normally, when the airplane is neither ascending nor 
descending, the pressure both inside and outside the 
capsule is equal, and the instrument hand reads "zero." 
The face of the instnmient is marked both in a 
zero-to-2000-feet clockwise direction and a zero-to- 
2000-feet counterclockwise direction. Each increment 
or marking represents 100 feet per minute. The unit 
pointer— hand— rotates from the zero mark in either 
a clockwise or counterclockwise direction. Normally, 
the instrument has a sector stop which limits the 
motion of the pointer, for either ascent or descent, to 
1900 feet per minute. All rates of climb have an in- 
herent lag of six to nine seconds because of a built-in 
restriction which prevents instrument oversensitive- 
ness which might be caused by bumpy air. 

The Magnetic Compass 

The magnetic compass ( Figure 71 ) is a navigational 
instrument used to indicate the heading on which the 
airplane is flying. The magnetic compass consists of 
a metal bowl filled with a liquid and a numbered, 
magnetic card element which has attached to it a 
system of magnetized needles. This card and the mag- 
netized needles are suspended on a pivot and are 
always free to turn. The magnetized needles normally 
point toward magnetic north. The magnetized card is 
calibrated into a 360-degree circle. A reference line, 
called the lubber line, and the graduations of the card 
are always visible through a glass window on the 
front of the bowl. 

Figure 71 — Mognetic Composs 

The liquid inside the instrument— a mixture of kero- 
sene and mineral oil which will not freeze— dampens 
the oscillations of the card. There is also an expansion 
chamber built into the compass to provide for ex- 
pansion and contraction of the damping fluid— which 
would result from altitude and temperature changes. 
The magnetic compass also has permanent magnets 
located above the card, which compensate for com- 
pass deviations that are caused by radio, electrical 
equipment, and metal parts of the aiiplane. The com- 
pensating assembly, or magnets, may be rotated by 
adjusting screws which are marked N-S and E-W on 
the face of the magnetic compass. 

The compass is mounted in the airplane so that the 
lubber line and the card pivot are aligned parallel to 
the longitudinal axis of the airplane. The magnetic 
compass is the only instrument in the airplane which 
indicates earth's magnetic north. 

The magnetic compass, however, is subject to errors 
which must be taken into consideration "when estab- 
lishing a true heading." Variation is caused by the 
difference in the geographical location between the 
True North and the Magnetic North. Since the mag- 


netic compass always points to Magnetic North, 
magnetic variation is always indicated on aeronautical 

Errors in the magnetic compass can also be caused 
by acceleration, turning, and by bumpy or rough air 
since the card swings while it tries to keep itself 
aligned with Magnetic North. 


The tachometer is an engine instrument and is used 
to measure the engine crankshaft speed in revolutions 
per minute (rpm). 

On airplanes equipped with fixed pitch or adjust- 
able pitch propellers this instrument is of primary 
importance because engine speed is directly related 
to the power output of the engine. The tachometer 
responds instantly to any change in engine speed. 

Some specific uses of the tachometer, when used 
on airplanes with fixed pitch propellers, are ( 1 ) to test 
the engine and magnetos prior to takeoff, (2) to aid 
the pilot in selecting the best jDOwer settings, (3) to 
indicate a loss in power, and (4) to indicate safe 
operating limits of the engine. 

There are two types of tachometers used on modem 
airplanes : ( 1 ) magnetic tachometers, and ( 2 ) electric 


The magnetic tachometer (Figure 72) derives its 
name from its internal mechanism. It is similar to and 
works on the same principle as an automobile speed- 
ometer except that it is calibrated in revolutions per 
minute (r^im) instead of miles per hour (mph). The 
magnetic tachometer is driven by a flexible shaft 
encased in a metal housing. On some of the smaller 
engines the flexible tachometer shaft is driven from 
an extended shaft on one of the oil pump gears 
located on the back of the engine. On other engines 

a special tachometer drive is used which consists of a 
gear train meshing with an accessory gear on the back 
of the engine. 

The mechanism of the tachometer consists of a ro- 
tating magnet, a round drum, and a hairspring. The 
rotating magnet is driven by the tachometer shaft 
through suitable couplings. The round drum or cup 
fits loosely over the rotating magnet and is fastened 
to a staff or shaft which is geared to the pointer shaft. 
The hairspring is attached to the shaft on the drum. 
When the rotating magnet is turned, the force or pull 
of the magnetic field pulls the drum against the force 
of the hairspring. When the force of the magnet 
equals the strength of the spring, the drum turns and 
rotates the pointer shaft by means of the gearing. The 
faster the rotating magnet turns, the more lines of 
magnetic force are applied to the drum, causing the 
pointer to move and thereby show an increase in rjim. 
The face of the instrument is calibrated in increments 
of 100 rpm. 

Figure 72 — Mognetic Tachometer 


73 — Electricol Tachometer 



The electric tachometer (Figure 73) consists of 
two units: the indicator, which is mounted on the 
instrument panel, and the generator, which is attached 
to the tachometer drive of the engine. The two units 
are connected by means of an insulated electrical 
cable. Because this instrument needs no flexible ta- 
chometer shaft to drive its mechanism, it is readily 
adaptable to multi-engine installations and to those 
aircraft where the distance from the engine to the in- 
strument panel is excessive. The electric tachometer is 
actually a voltmeter, but calibrated in revolutions per 
minute instead of in volts. The mechanism, contained 
in the indicator unit, is a permanent magnet with a 
moving coil connected to a pointer. The moving coil 
moves within the air gap of the permanent magnet. 
The pointer and coil movement are dampened by a 
hairspring and are mounted in jewelled bearings 
which permit steady and accurate readings. The elec- 
trical output of the tachometer generator is routed 
through a coil in the indicator unit. As engine speed 
increases the tachometer generator increases its energ\ 
output. This increased voltage feeds into the moving 
coil of the indicator unit and causes the coil to move 
against the restraining hairspring, thereby indicating 
an increase in rpm. A decrease in engine speed results 
in a decreased voltage output of the tachometer 
generator and the hairspring is then able to overcome 
the attraction between the coil and the permanent 
magnet, thereby causing the pointer to move toward 
the lower end of the scale. 

Oil Pressure Gage 

The oil pressure gage (Figure 74) is an engine in- 
strument required on all airplanes. It shows the pres- 
sure at which the lubricant is being forced into the 
bearings and to the other points of the lubricating 
system. Among the uses of the oil pressure gage are 
(1) a warning of an impending engine failure if the 
oil pump fails or oil lines break, and (2) visual indi- 

Figure 74 — Oil Pressure Gage 

Figure 75 — Bourdon Tube 

cation that oil is circulating under proper pressure 
before takeoff. 

The oil pressure gage is calibrated in pounds per 
square inch (psi). The instrument contains a Bourdon 
tube mechanism (Figure 75) which is used in almost 
all fluid pressure gages. A Bourdon tube is a hollow 
ciu-ved tube made of spring-tempered brass or bronze 
and has an elliptical cross-section. It is sealed at its 
outer end. The outer end of the tube is free to move, 
while the other end is rigidly fastened to the instnr- 
ment case. The outer or free end of the tube is at- 
tached to a lever and gear segment which actuates 
the pointer. The stationary end of the tube has an 
opening connected to a fitting on the back of the 
instrument case. The fitting has a restriction to prevent 
surging and oscillation of the pointer. An oil line from 
a high pressure passage in the engine connects to the 
restricted fitting on the back of the instrument case. 
When the engine is started, some pressure should be 
indicated on the oil pressure gage almost immediately. 
If no pressure is indicated after thirty seconds of oper- 
ation, the engine should be shut off and the cause for 
operational failure investigated so as to prevent dam- 
age to the engine. 

Oil Temperature Gage 

The oil temperature gage ( Figure 76 ) is an engine 
instiument used on all aircraft. The Federal Aviation 
Agency requires a suitable means for taking the oil 
temperature as it enters the engine. This FAA require- 
ment is important since oil plays a big part in the 
cooling of aircraft engines. 

The oil temperature gage is used ( 1 ) to enable the 
pilot to operate the engine within safe operating tem- 
peratures, and (2) to warn the pilot of engine over- 
heating. The oil temperature gage used on most 
aircraft is a vapor pressure type thermometer and is 
calibrated in degrees of Fahrenheit or Centrigrade. 


Figure 76— Oil Te 

alure Gag 

A vapor pressure thermometer consists of tliree 
units: the indicator unit, which is mounted in the in- 
strument panel; the bulb, which is located at the point 
of temperature measurement; and the capillary tube, 
which connects the indicator to the bulb. 

The indicator unit contains a Bourdon tube mecha- 
nism similar to the oil pressure gage except that the 
Bourdon tube also has a progressive restrainer to per- 
mit the use of a uniformly graduated scale. The pro- 
gressive restrainer is necessary because vapor pressure 
does not increase uniformly with temperature. The 
bulb is a hollow brass cylinder about three inches long 
and one-half inch in diameter. It contains a volatile 
liquid, meth\l chloride, which actuates the instrument 
or indicator unit. 

The capillary tube is a very small annealed copper 
tube protected with either a shield of braided wire or 
a helical wound tube. The capillary tube connects the 
bulb and the indicator unit and is used to transmit the 
vapor pressure from the bulb to the opening in the 
Bourdon tube. 

The operation of the vapor pressure thermometer is 
entiiely automatic. As the temperature of the bulb 
increases, the liquid methyl chloride, being very 
volatile, changes to a gas. This change causes an in- 
crease in pressure which is transmitted through the 
capillary tube to the Bourdon tube. The Bourdon tube 
tends to straighten out and its movement is transmitted 
through the linkage to the pointer on the face of the 

The three units of a vapor pressure thermometer are 
integrated and cannot be taken apart without losing 
the gas and thereby rendering the instrument useless. 
For this reason care must be taken to prevent cutting, 
denting, or stretching the capillaiy tube. 

Turn and Bank Indicator 

The turn and bank indicator (Figure 77) is a flight 
instrument which is actually a combination of two 
instruments. It combines an inclinometer— a pendulous 

device— and a rate of turn indicator— a gyroscopic de- pigu 

Figure 77 — Turn and Bonk Indicator 

vice. It is becoming a widely-used flight instrument, 
especially under conditions of jioor visibility. 

The turn and bank indicator enables the pilot ( 1 ) to 
maintain straight and laterally level flight, (2) to 
make precision turns at pretermined rates, and (3) 
to coordinate rudder and ailerons when making 
banked timis. It may be either a vacuum-operated 
instrument or an electrically-driven instrument. Both 
types operate in the same manner and on the same 
general principles. 

The turn indicator portion indicates motion about 
the vertical axis of the airplane and measures the rate 
of this motion. It is composed of a suction or vacuum- 
driven gyro rotor located in the rear of the instrument 
case, a restraining spring, a dashpot for damping, and 
an indicator needle or hand to indicate the rate of 
turn. The dial is marked with the letters "L" and "R" 
and also has a neutral position with an index mark 
on each side. The index marks indicate a timed one- 
minute turn of 360° when the needle coincides with 
the index. The turn indicator operates on the gyro- 
scopic principle of precession. Due to the rigidity of 


Left turn ~ Left turn 

Skidding out. not enough bonk Slipping in, too muctibank 

Figure 79 — Visual Indications of Various Turn and Bank Conditions 

a spinning gyro, it tends to precess at right angles to 
an applied torque. The gyro rotor is mounted so that 
it turns about the lateral axis of the airplane. When 
mounted in this manner, the gyro responds only to 
motion about the vertical axis of the airplane. 

If the airplane turns to the left, (Figure 78) the 
gyro assembly rotates as indicated by the arrow "b." 
The immediate reaction of the gyro to this turning 
force is a rotation "c" about the "X" axis until "Z" has 
aligned itself with the original position of "Y." This is 
the natural reaction of a gyro mounted in this manner 
and is called precession. 

The precession of the gyro, or its reaction to the 
applied torque, acts against the force of a restraining 
spring and is limited by stops to a movement of about 
45 degrees from each side of the vertical. The spring 
serves to balance the gyroscopic reaction or precession 
during a turn and to return the assembly to its neutral 
or vertical position as soon as the airplane assumes a 
straight flight pattern. The action of the gyro assembly 
is damped by the dashpot and when properly adjusted 
the displacement of the gyro and the needle is directly 
proportional to the rate of turn of the airj^jlane. When 
centered, the needle shows that the airplane is flying 
straight, disregarding drift, pitch, and bank. When the 
needle is off center it indicates that the airplane is 
turning in the direction shown by the needle. Figure 
79 shows indicator readings for several different con- 

The bank indicator portion of the instrument con- 
sists of a black glass ball inside a curved glass tube. 
The glass tube contains a nonfreezing liquid which 
serves as a damping fluid. The bank indicator or in- 
clinometer is located in the front of the instrument 
case and is visible through the instrument's glass cover. 

The action of the bank indicator can be compared 
to a pendulum which is acted upon by centrifugal 

force. It shows motion about the longitudinal axis of 
the airplane. When the airplane is making a perfectly 
banked turn, the ball, due to centrifugal force, remains 
in the center of the glass. The correct bank is always 
indicated for any tiu-n, but no indication is ever given 
of the amount of bank. In straight flight or in a turn, 
the centered ball indicates proper lateral attitude of 
the airplane. If the ball moves in the direction of the 
turn, it indicates that the airplane is slipping, i.e., the 
angle of bank is too steep. If the ball moves in a 
direction opposite to the turn, it indicates that the 
airplane is skidding toward the outside of the turn, 
i.e., the airplane is not banked enough. 

The indications of these two instruments combined 
in one dial always show the rate of turn and the lateral 
attitude of the airplane during straight flight or during 

The Directional Gyro 

The directional gyro is a navigational instrument 
sometimes called a gyro compass or a turn indicator. 
This instrument establishes a fixed reference point to 
assist the pilot in maintaining flight direction. Unlike 
a magnetic compass the directional gyro has no direc- 
tive force to return it to a fixed heading. It must be 
checked occasionally and, if necessary, reset by a 
caging knob. 

The directional gyro (1) supplements the compass 
in keeping "on course," (2) shows the amount of turn, 
(3) maintains alignment when making instrument 
landings, and (4) aids in locating radio beacon sta- 
tions. (Figure 80.) It is a horizontal, axis-free compass 
provided with an azimuth card and a setting device. 
The instrument, itself, is vacuum operated by suction 
from the engine-driven vacuum pump or the venturi 

The spinning gyro rotor is mounted horizontally and 
is supported in a gimbal ring which is free to turn 
about an axis on bearings in the vertical ring. The ver- 

Figure 80 — Directional Gyro 


tical ling is mounted in bearings and is free to turn 
about the vertical axis. The circular azimuth card visi- 
ble through the instrument cover glass is graduated in 
degrees and is attached to the vertical ring. A caging 
knob in the front of the instiimient is used to set the 
card on a desired heading and to cage the gyro. When 
the knob is pushed in, it engages a pinion gear to a 
gear attached to the gimbal ring. By turning the knob, 
when it is thus engaged, the gimbal ring, vertical ring, 
and azimuth card can be rotated to any desired head- 
ing. The rotor, spinning at appro.ximately 12,000 rpm, 
obeys a gyroscopic principle of rigidity. Thus the 
rotor, gimbal ring, and the circular azimuth card 
remain fixed, the airplane moving around them. 

When establishing a course, the pilot refers to the 
magnetic compass, then cages the gyro and selects 
a heading by use of the caging knob. After setting the 
card, the knob is pulled out, and the instrument is 
then in operation and will function properly until it is 
either upset or recaged. 

Any bank in excess of 55 degrees will upset the gyro 
and cause the card to spin. The airplane must then 
be leveled, the gyro caged, and reset. The directional 
gyro will gradually drift off a heading over a period 
of time and should be reset at 15-minute intervals. 
Gyro drift should not exceed 5 degrees in 15 minutes 
on any single heading. Care should be taken in both 
setting the instrument and uncaging the gyro. The 
knob must always be pidled straight out with no turn- 
ing motion. If the knob is turned, even slightly, the 
card will begin to turn slowly and the instrinnent's 
natural tendency to drift off course will be speeded up. 

The Gyro Horizon 

The gyro horizon ( Figure 81 ) is a flight instrument 
often called an artificial horizon or an attitude gyro. 
By visually showing a miniature airplane and a gyro- 
actuated horizon, the pilot can look at the instrument 
and determine his flight attitude without reference 
to the ground. 

The gyro horizon ( 1 ) enables the pilot to orient 
himself under conditions of poor visibility by provid- 
ing a reference in the form of an artificial horizon; 

(2) shows the attitude of the air]^)lane's flight with 
reference to the real horizon and to the ground; and 

(3) aids in maintaining the proper glide angle when 
making an instrument landing. 

The gyro horizon is a vacuum-driven instrument 
which utilizes vacuum or suction from the vacuum 
pump or venturi tube as its source of power. The 
instnmient has a gyro rotor, which spins at approxi- 
mately 12,000 rpm, mounted in a case. The rotor is 
mounted so that its axle is vertical, thus allowing it 

Figure 81 — Gyro Horizon 

to spin in a horizontal plane. The case contains the 
rotor, on pivots, which is attached to a gimbal ring 
The horizon bar is attached to an arm pivoted at the 
rear of the gimbal ring and is controlled by the gyro 
tlirough a guide pin. This entire assembly is mounted 
on pivots located at the front and the back of the case. 
The dial is an integral part of the gimbal mount and 
follows the precession movement of the rotor. A minia- 
ture airplane image is located on the front of the 
instrument and is adjustable. The gyro horizon always 
indicates the attitude of the airplane in which the in- 
strument is mounted. 

A caging knob is located on the front of the instru- 
ment to level the internal mechanism properly when 
it is upset. The limits of operation of the gyro horizon 
are 60 degrees of pitch and 90 degrees of bank. Any- 
time that these limits are exceeded, the mechanism 
will be upset and its readings will be erroneous. 

The gyro horizon operates on the same fundamental 
gyroscopic principle as the directional gyro, i.e., 
rigidity. When the rotor is spinning, it will maintain 
itself in its plane of rotation unless upset. On the face 
of the instrument the position of the gyro rotor is 
indicated by the horizon bar, which is actuated by 
a pin protruding from the gyro case through a slot in 
the gimbal ring. Any tendency of the gyro to depart 
from its true position is corrected by a pendulous de- 
vice which constantly maintains the axle of the gyro 
in its vertical position. 

The horizon bar remains stationary. Only the instru- 
ment case and the miniature airplane move when the 
airplane is banked, nosed up, or nosed down. To keep 
the aiq^lane laterally level, the miniature airplane is 
kept parallel to the horizon bar. To keep the airplane 
longitudinally level the miniature airplane must keep 
the same position with reference to the horizon bar as 


the nose of the airplane keeps with reference to the 
earth's horizon. Sometimes this may be a shghtly nose- 
up or nose-down attitude, dep)ending on power and 
load. The easiest way to determine the correct posi- 
tion of the miniature airplane with respect to the 
horizon bar is to observe the rate of climb indicator. 
If this instrument indicates level flight with neither 
a rate of ascent nor a rate of descent, then the minia- 
ture airplane can be manually set to coincide with the 
horizon bar. A graduated scale from to 90 degrees 
both left and right are located on the outer circum- 
ference of the instrument face to indicate the degree 
of bank. An inde.x mark is provided on the curved 
portion of the dial as a reference point. 


As the design of the modern airplane has become 
more complicated over the years, it has resulted in an 
increased number of complex mechanical devices, de- 
signed to measure the performance of the airplane. 
These instruments are divided into three classes : ( 1 ) 
flight, (2) engine, and (3) navigation. The aircraft 
and engine manufacturers, in cooperation with the 
Federal Aviation Agency, have established safe oper- 
ating limits for the airplane's airframe and engine. 
These safety limits are indicated either by markings 
on the instruments or by placards in the cockpit. 

The pitot-static tube and the venturi tube are neces- 
sary to the proper operation of many of the airplane's 
instruments. Some airplanes, however, use a vacuum 

pump instead of a venturi tube to supply suction for 
the gyro instruments. 

Flight instruments include the airspeed indicator, 
altimeter, rate of climb indicator, turn and bank in- 
dicator, and the gyro horizon. The airspeed indicator 
is the airplane's speedometer, measuring the airplane's 
speed through the air rather than over the ground. 
The altimeter indicates the airplane's altitude either 
above the airport or above sea level. The rate of climb 
indicator shows that the airplane is either ascending 
or descending. The turn and bank indicator demon- 
strates the airplane's angle of bank and rate of turn. 
The gyro horizon is a visual aid which represents the 
attitude of the airplane with respect to the earth's 

Engine instruments include the tachometer, oil pres- 
sure gage, and oil temperature gage. The tachometer 
shows the engine speed and in some cases indicates 
the power output of the engine. The oil pressure gage 
indicates the amount of pressure of the oil when it is 
circulating in the engine. The oil temperature gage 
provides a means of determining oil and engine tem- 

The two navigation instruments are the magnetic 
compass and the directional gyro. The magnetic com- 
pass always points to the earth's Vlagnetic North and 
provides the pilot with a means by which he can 
determine the direction of the airplane's flight path. 
The directional gyro serves as a fixed reference point 
and aids the pilot in maintaining directional control 
of the airplane. 


1. How may the safe, economical and reliable 
operation of an airplane best be determined? 

2. How are instruments classified? 

3. Who determines the safe operating limits of an 

4. What detemiines instrument requirements? 

5. What is a venturi tube used for? 

6. How does a venturi tube cause a decrease in 

7. What is the disadvantage of a venturi tvibe as 
compared to an engine driven vacuum pump? 

8. If an airplane was traveling 150 mph with a 
tailwind of 20 mph, what would its groundspeed 

9. What instrument is used to determine the best 
climbing and gliding angles? 

10. What is the primary difference between a Gyro 
\ compass and a magnetic compass? 

11. Which flight instrument would indicate the rate 
of change in altitude? 

: 12. Why would a pilot use the altimeter setting 

system when flying cross country? 

13. Is compass deviation the same as magnetic varia- 

14. Which instrument would be used to indicate 
power setting on an airplane with a fixed pitch 

15. Why is oil temperature so important on an air- 
craft engine? 

16. Which flight instrument is best suited to indicate 
a proper banked turn? 

17. ■ What would be indicated to the pilot if the black 

ball of the turn and bank moved in a direction 
opposite the turn? 

18. Which flight instrument would show the attitude 
of the airplane's flight with reference to the 
earth's horizon? 

19. Which navigation instrument aids the pilot in 
determining direction other than the magnetic 

20. What advantage does the electrical tachometer 
have over the magnetic tachometer? 

Chapter 7 Flight Technique 

The flight techniques employed by the Wright 
brothers during their experimental flights at Kitty 
Hawk in 1903 are comparatively the same as those 
used by modern-day pilots. This chapter will dis- 
cuss the primary techniques wliich all pilots employ 
whether they are flying small, propeller-driven air- 
craft or huge jet-propelled airliners. 

Airplane Attitude and Controls 

When discussing flight maneuvers, the word "atti- 
tude" is frecjuently used. Attitude describes the posi- 
tion of the airplane in space with respect to the 
ground, i.e., it defines the "squareness with the earth" 
of the wings and fuselage. For example, a nose-high 
or climbing attitude would mean that the longitudinal 
axis of the airplane is inclined upward with respect to 
the plane of the earth's surface. 

Attitude must not be confused with either the angle 
of attack or the flight path. The flight path is the direc- 
tion, up and down as well as sideways, taken by the 
airplane and is a result of attitude and power. The 
angle of attack is the angle at which the wing strikes 
the air. 

The four fundamental flight attitudes are ( 1 ) 
straight and level flying, (2) climbing, (3) gliding, 
and (4) turning. All four attitudes are controlled from 
the cockpit by the elevator, the ailerons, and the rud- 
der controls (Figure 82) while altitude is controlled 
only by the throttle or power setting. 


The throttle controls the engine power, which, 
through the propeller, develops the thrust that propels 
the airplane through the air. Airflow around the wing 
produces the lift which enables the airplane to climb, 
descend, fly straight and level, or make turns. 

The elevator control (Figure 82) (stick or control 
column) moves the hinged elevator up or down. In 

normal flight, movement of the control forward de- 
presses the elevator, raises the tail, and makes the nose 
point downward. Movement of the control to the rear 
raises the elevator, depresses the tail, and makes the 
nose point upward. 

The hinged rudder (Figure 82), controlled by the 
rudder pedals, yaws or swings the airplane about its 
vertical axis, i.e., points the nose toward the right or 
left. For example, right rudder pressure moves the 
trailing edge of the rudder to the right and causes 
the airplane's tail to swing to the left and the nose 
to the right. Left rudder pressure moves the trailing 
edge of the rudder to the left and causes the airplane's 
tail to swing to the right and the nose to the left. 

The ailerons ( Figure 82 ) , connected to the stick 
or wheel, give the airplane a rolling motion. Move- 
ment of the stick (or wheel) to the right depresses 
the left aileron and raises the right aileron, thereby 
increasing the lift of the left wing and decreasing 
the lift of the right wing. This action causes the air- 
plane to roll to the right. Pressure on the stick (or 
rotation of the wheel) to the left has the opposite 


During straight and level flight the throttle is set 
to produce constant power when the rudder, elevators 
and ailerons are streamlined, i.e., lined up with their 
respective fixed surfaces— rudder with fin, elevators 
with horizontal stabilizer, and ailerons with wing. In 
straight and level flight the lateral and longitudinal 
axes of the airplane are parallel to the earth's surface, 
and the yawing or vertical axis is perpendicular to 
the earth's surface. 

If this stiaight and level flight attitude is disturbed 
by rough air or by movement of the controls, it is 
corrected by the coordinated use of stick (or wheel) 
and rudder. As will be explained in detail later, the 
rudder and ailerons are always used together. For 





c-::."H!:::r'::s;r "' "- '°""'"'- '->-' coB,es one 


During straight and level ftiaht f r 
att,tude-«/„,i^,„d W fS e sT) S'^'"" f T^ 
at slow airspeed or when thraltl' u^ ^'^^' 

loaded^ the angle of attack n^'s Ct^^:.:, o"^"^ 
duce the needed lift reauired fr, .'"f^^^-^f ^ to pro- 
at a given power etX Th ° "" "" ^?''' ^'^^^ 
changing the airnhnT If . ^ '' accomplished by 
positfon and a the ^ T'^' '° ^ ^''Shtly nose-high 

trim tabTtCl^lir" r f *"^""S '^' ^'-^'o'" 
^"^^ '^ "^'^ maintain the new attitude. 


POS.L (FigTrfsT) s l^t ^ddittf t "°^^-''^^ 
an increased angle o attaci; vn P"'^^'' ^"^ 

thereby raise the .1^? TU^" '"""'^"'^ '^' ^'^' ^^^ 
be coinpared to dW " '' P'-oeedure may best 

eas • thaf ic- I, uiiver must step on the 

Se; 1 e etaT::l""T" ™^'"' .»»- since i 


.£"; ri,-,r :;•-:• •'•■••> -"' 

» re<,„e„„„ ,„ .pee" tt" TZ £^"7 '°'«.' 
Earths gtlV„L»%''r?'* ?™' •'■'»"■"""■'■ 
controls the airspeed hv arl- !- ^ ' however, 


arag and lift equals weight-and the 




aircraft descends at a constant rate and at a constant 

This rate of descent cannot be controlled by chang- 
ing the airplane's attitude. If the nose were raised, 
for example, the speed would decrease and lift be 
reduced in the same proportion that lift was increased 
when the angle of attack was increased. Consequently, 
there is no change in either the lift or the rate of 
descent. In contrast, if the nose were lowered, the 
angle of attack would decrease and the speed increase, 
again without noticeable effect on lift or rate of 
descent. The only way in which a pilot can control 
the rate of descent is by changing the power setting, 
i.e., the rate of descent can only be reduced by increas- 
ing the angle of attack and by keeping the same air- 
speed through an addition of jwwer. Once again a 
definite relationship between engine power, airplane 
attitude, and airspeed is apparent. 


An airplane, like any moving object, requires a 
sideways force to make it turn. In a normal turn this 
force is developed by banking, the wings so that lift, 
which always acts perpendicular to the span line of 
the wings, is exerted sideways as well as upward. 

The lift in a turn is divided into two parts: one 
acting vertically and opposite to the force of gravity; 
the other acting horizontally and in the direction of 
the tvirn. (Figure 85.) When the airplane is banked 
the horizontal lift pulls the airplane sideways and as 
the banked airplane is pulled to the side, the air 
pressure on the vertical side of the tail surfaces pushes 
the tail around the turn in much the same way that 
a weathervane is turned when wind blows on it from 
the side. As long as the airplane is banked, this 
weathervaning takes place and results in a continuous 
turning movement. 

In a properly executed turn, therefore, the turning 
force is not supplied by the rudder since an aircraft 
cannot be steered around a corner in the same manner 
as an automobile; it must be banked. If an airplane is 
not banked, there is no force to pull it from a straight 
flight path, unless the aircraft is skidded. 












Figure 83 — The Factors Affecting Attitude 









Figure 84 — The Aerodynamic Functions of an Airplane Wing in a Climb with Power Constant 


During entry into and recovery from turns, and at 
any other time that the ailerons are used, the rudder 
is used to counteract aileron drag, often known as the 
adverse ijaw effect. Adverse yaw is the tendency of 
an airplane to swing (yaw) momentarily toward the 
side of the down-turned aileron, or away from the 
desired direction of turn. Adverse yaw is caused by 
an increased drag of the lowered aileron on the wing 
which is being raised. 

When right stick, for example, is applied, one would 
expect the airplane to bank and to turn to the right. 
However, as soon as aileron is applied the drag pro- 
duced by the lowered left aileron holds back the 
left wing, causing the nose to swing moiuentarily to 
the left. When the airplane begins to bank to the 
right, the inclined lift force then pulls the airplane 
into a right turn. 

Adverse yaw is nullified by applying rudder and 
aileron control at the same time. In the above exam- 
ple, right rudder used in coordination with the right 
aileron swings the nose of the airplane immediately 
to the right, balancing the adverse yaw effect to the 
left. After the bank is established, both the rudder 
and aileron controls are returned to a center or neutral 


When the airplane is in a turn, the wing on the 
outside of the circle travels faster than the wing on the 
inside of the circle, e.g., a person sitting on the out- 
side edge of a merry-go-round moves faster than a 
person sitting nearer to its center. The greater speed 
of the outer wing causes it to have more lift than the 

inner wing and therefore the airplane has a tendency 
to overbank. This overbanking tendency is counter- 
acted by applying opposite aileron. 


As illustrated in figure 86, banking the airplane 
causes a loss of vertical lift, i.e., the airplane will lose 
altitude in a turn unless the vertical part of the lift 
is increased to equal the weight of the airplane. An 
increase in vertical lift is produced by increasing the 
angle of attack with the elevators. As the angle of 
attack is increased, the drag also increases and slows 
the airplane. Therefore, in order to maintain a con- 
stant airspeed, more power must also be added. 


At a given airspeed, the rate at which an airplane 
turns depends upon the force which is pulling it out 
of a straight path, i.e., upon the size of the horizontal 
part or component of the lift. This depends directly 
on the angle of bank. The greater the angle of bank, 
the faster the rate of turn will be. Also, the greater 
the angle of bank, the more power that must be added 
to maintain vertical lift and avoid losing altitude. 


An airplane points directly along its flight path 
except when it is being slipped or skidded. Using 
only the rudder to yaw the aiiplane, the nose can be 
skidded either to the right or to the left of the direc- 
tion in which the airplane is moving. If the wings are 
held level, the airplane will slide through the air side- 
ways and slowly change its flight path. (Figure 87.) 
This is called a skiddin<j[ turn. 












Figure 86 — Loss of vertical lift 
moving toward the horizontal. 

a turn due to component of lift 

L_Lift U — Vertical Lift 

W — Weight L„— Horizontal Lift 
Lr — Resultant Lift 

The airplane is not pointed in the direction of its 
flight path. In a skidding turn to the right, for exam- 
ple, the nose points to the right of the flight path, but, 
upon release of the rudder pedal pressure, the air- 
plane weathervanes and points once again in the 
direction of the flight path. 

Similarly, the airj^lane may be skidded while exe- 
cuting an ordinary banked turn by applying too much 
rudder or by failing to return the rudder pedals to a 
neutral position after the turn has been started. The 
skid tends to carry the airplane outward— away from 
the direction of turn— and the pilot's weight is also 
forced toward the outside of the turn. 

If the wings are not held level with the ailerons, 
and rudder alone is applied, the airplane yaws, 
i.e., one wing moves forward faster than does the 
other wing. However, this increased wing speed also 
increases wing lift; consequently, the airplane banks. 
When the airplane banks, it is pulled from its straight 
flight path as explained above. If rudder pedal pres- 
sure is released after a given angle of bank is estab- 
lished, a normal turn will result. Back pressure on the 
elevator column is required, however, to compensate 
for the decreased vertical lift, but the turn will have 
been made with only the rudder, causing the airplane 
to skid at the beginning of the turn. 

An airplane may be slipped either without changing 
its heading or while in a turn. In a straight slip the air- 
plane is banked with ailerons but prevented from 

Figure B5 — The Forces Acting on on Airplane in a Normal Turn 

Figure 87— A Skidding Tur 
Wings Held Level 

Caused by Rudder Being Applied v»ith 


turning by the use of the opposite rudder. The direc- 
tion the airplane is pointed does not change, but the 
bank causes the aircraft to be pulled sideways. The 
resulting decreased lift from the inclined airfoil causes 
the airplane to lose altitude. 

Slipping also takes place during a banked turn if 
the airplane is not allowed to turn as fast as it should 
in respect to the angle at which it is banked. This 
kind of slipping is caused by holding some pressure 
on the outside rudder pedal. In a slip during a turn, 
the weight of the pilot is forced toward the inside 
of the turn. 

Use of either aileron or rudder alone during normal 
flight results in slipping or skidding and should be 
avoided. When entering turns, the two controls should 
be used together so that the nose starts moving in the 
desired direction at the same moment that the air- 
plane begins to bank. 

Many flight conditions, principles, and maneuvers 
are difficult for the student to visualize by merely 
reading a text. Visual aids and demonstration devices, 
therefore, are recommended for classroom use. Wind 
tunnels, instrument mockups. Link trainers, and model 
airplanes, are among many instructional devices pres- 
ently available. 

The Takeoff 

After a visual preflight inspection of the aircraft, 
the pilot starts the engine and taxis to the downwind 
end of the runway which he will use for takeoff. Dur- 
ing the takeoff, the airplane is always headed into the 
wind so that the additional speed of the air over the 
wing will permit a shorter takeoff run. Stopping 
at least 100 feet from this runway, the pilot checks 
his engine and all other systems and instruments on 
the airplane. When he is satisfied that everything is 
working properly, he taxis onto the runway. As soon 
as he is lined up on the runway, he slowly and 
smoothly opens the throttle. By means of rudder 
control, he keeps the aircraft on a straight course 
as the plane gathers momentum. 

If the airplane has a conventional landing gear 
(with tail wheel), the control column is pushed for- 
ward to raise the tail, changing the airplane's attitude 
from a three-point to a slightly nose-high attitude. If 
the airplane has a tricycle gear, a little back pressure 
is applied to the control column to raise the nose gear 
off the runway, again putting the airplane into a 
slightly nose-high attitude. When the speed becomes 
great enough to generate sufficient lift, the airplane 
leaves the nmway. At this point the nose is lowered 
slightly so that the airspeed may increase quickly 
to the normal climbing airspeed. When this airspeed 

is reached, the pilot reduces the throttle setting from 
maximum takeoff power to climb power and puts the 
airplane into the normal climbing attitude. 

The pilot will continue to climb straight ahead until 
he reaches an altitude of 400 to 1,000 feet, depending 
upon the type of airplane he is flying. At the specified 
altitude he will leave the traffic pattern. If the airjjort 
is served by a control tower, the tower may give him 
definite instructions for leaving the pattern. In the 
absence of tower instructions, he will leave the pat- 
tern according to the standard procedure established 
for airports which are not served by a control tower, 
i.e., a 90 degree turn to the left and then a 45 degree 
turn to the right. ( Figure 88. ) 

Landing Approach 

To land at any airport the pilot again uses a stand- 
ard procedure unless otherwise directed by the air- 
port's control tower. The standard pattern consists of 
a downwind leg, a base leg, and a final approach. 
( Figure 88. ) 

On the downwind leg, the airplane flies with the 
wind and parallel to the active runway. It is on 
the downwind leg that the pilot completes the pre- 
landing check and reduces power. The point at which 
he begins his descent and the manner in which he 
continues it to the end of the runway depends upon 
the type of airplane he is flying. In small, slow air- 
planes, the pilot continues level flight on the down- 
wind leg until the airplane is directly opposite the 
touchdown spot. At this point, the throttle is closed 
completely and a power-off glide, which will include 
two 90 degree turns to the left, begins. After making 
the first 90 degree turn, the pilot is on the base leg. 
This leg of the landing pattern is crosswind and per- 
pendicular to the runway. On the base leg the pilot 
opens the throttle momentarily in order to keep the 
engine from cooling too rapidly during the glide. The 
second 90 degree turn to the left places the airplane 
on the final approach leg, at which point it continues 
to glide to the point of landing. This is called the 
power-off approach and landing. 

In larger and or faster airplanes, the throttle is not 
usually closed completely on the downwind leg since 
a power-on approach is more appropriate. In a power- 
on approach, the pilot controls his rate of descent 
by varying the power setting. His aim is to have a con- 
stant and moderate rate of descent as he continues 
around the pattern to the point of landing. Just before 
reaching the point of contact with the runway, the 
pilot closes the throttle completely. Also, with larger 
and^^or faster airplanes, the pilot may make a shallow 
left turn of 180 degrees from downwind leg to final 



leave traffic Ii5° 


Heavy or fast 
aircraft departure 





approach rather than two steeper 90 degree turns. Re- 
gardless of the size or speed of the aircraft, there are 
two methods which can be used to touch down with 
conventional landing gear. 

One method of landing an airplane with a conven- 
tional gear is to make a wheel landing, i.e., touch down 
on the two main wheels only, keeping the tail wheel 
off the runway. When the airplane descends to the 
bottom of the final approach, the pilot applies back 
pressure on the control column and levels off a few 
inches above the runway. Since the airplane has no 
power at this point, its forward speed rapidly de- 
creases. As the speed decreases, the wings produce 
diminishing lift and the airplane settles slowly to the 
runway. To prevent the airplane from settling too rap- 
idly, resulting in a hard landing, the pilot constantly 
increases the back pressure on the control column, 
thereby permitting the airplane to touch down gently. 
As the airplane slows after contacting the runway, the 
tail wheel is allowed to touch down also. When the 
airplane has slowed to taxi speed, the landing is con- 
sidered completed. 

The second method often used to land with con- 
ventional gear is to make a three-point or full-stall 
landing, i.e., to touch down with all three wheels 
at the same time. This landing starts just as the wheel 
landing does, but differs in technique from the wheel 
landing only in the amount of back pressure the pilot 
applies to the control column. He does not allow the 
airplane to settle to the runway until the control col- 
umn is all the way back and the wings are completely 
stalled. This type of landing is well adapted to very 
light airplanes since the stalled attitude keeps gusts 
of wind from lifting the airplane from the runway 
after it has finally touched down. 

There is a slight variation in the landing technique 
of an airplane equipped with a conventional gear and 
one equipped with a tricycle gear. That used for 
landing an airplane equipped with a tricycle landing 
gear is exactly the same as that used for a wheel land- 
ing in those airplanes equipped with a conventional 
landing gear, except that, as the tricycle-geared air- 
plane slows after touchdown, the nose wheel, rather 
than the tail wheel, is allowed to contact the runway. 


Attitude, the relationship of the axes of an airplane 
to the earth's surface, is controlled with the stick (or 
wheel) and the rudder pedals. 

Forward and backward movement of the stick (or 
wheel) moves the elevators, causing the nose to move 

down or up. This changes the angle of attack, which 
is defined as the angle between the chord of the wing 
and the relative wind. 

Movement of the stick or rotation of the wheel to 
right or left controls the ailerons and produces bank- 
ing. Pressure or movement of the rudder pedals actu- 
ates the rudder, causing the nose to yaw or move to 
the right with right rudder pressure and to the left 
with left rudder pressure. 

During straight and level flight, the control surfaces 
are approximately streamlined with the surfaces to 
which they are attached and the four forces acting on 
the airplane in flight are balanced, that is, thrust 
equals drag and lift equals weight. 

Thrust is supplied by the engine and the propeller; 
drag is represented by anything which tends to retard 
the airplane during flight; lift is created by the wings; 
and weight is the expression of the force of gravity 
which tends to pull the airplane earthward. 

To climb, the angle of attack is increased and power 
is added. For any given attitude and power setting, 
a certain airspeed will result. In a glide, no power is 
used and the airplane must be nosed down to main- 
tain a safe flying speed^with the thrust, which at other 
times is supplied by the engine, being provided by 
gravity. During a powered descent, the amount of 
power used and the attitude established and main- 
tained by the elevators determines the rate of descent. 

Turns are produced by banking— the rate of turn 
being determined by the amount of bank. In order to 
turn without slipping or skidding, the rudder is co- 
ordinated with the ailerons when rolling into and out 
of the bank. While the airplane is in the bank, both 
controls should be in a neutral position. Some back 
pressure should be maintained on the stick or wheel 
to avoid losing altitude. 

Takeoffs are always made into the wind. By use of 
the rudders, the aiq^lane is held in a straight path 
while on the ground. During the takeoff run, the air- 
plane is put into a slightly nose-high attitude until 
sufficient speed is reached thereby creating lift and 
causing the airplane to leave the runway and become 

Landing technique is basicaUy the same for any 
airplane. Approaches to landings may be made by 
gliding (power off) or by using power (power on). 
When the airplane is leveled off within a few inches 
of the runway, it loses speed and consequently Ifft. 
To prevent too rapid a loss of lift, the airplane's angle 
of attack is gradually increased by back pressure on 
the stick or wheel. With this gradual loss of lift, the 
airplane settles to the runway. 



1. Explain the meaning of the word "attitude" as 
it is used when discussing flight maneuvers. 

2. What is angle of attack? 

3. What are the four fundamental flight attitudes? 

4. If you moved the control stick forward while 
flying an airplane, what effect would this ha\e 
on the attitude of the airplane? 

5. Describe briefly how an airplane, in flight, is 

6. What is the rudder used for in turning an air- 
plane in flight? 

7. What is slipping? Skidding? 

8. What is the correct attitude for an airplane as 
it leaves the runway on take-off? 

9. In speaking of an airport traffic pattern, what 
is the downwind leg? The base leg? The final 

10. When an airplane is approaching a runway for 
landing, which is the primary control for govern- 
ing the rate of descent? 

Chapter S Air Navigation 

Navigation, in some one of its many forms, is 
employed by every individual when he moves from 
"here" to "there." In early history, man moved about 
on foot and navigated by using prominent landmarks, 
such as trees, hills, valleys, bodies of water, contours 
of land, sun, stars, etc. These familiar features guided 
him away from home and back again safely. 

After the wheel was invented, man was able to 
travel farther, and consequently he needed a written 
record of these well-known signposts. This record was 
the basis for the development of the modem maps 
and charts. 

Travel was not limited, however, to land only. 
Water was often an easier form of transportation and 
permitted greater mobility for travelers and for trad- 
ers. The magnetic compass and more complex charts 
gave man much needed assistance in traversing new 
areas. Celestial navigation was evolved to ascertain 
direction more accurately, thus enabling man to travel 
more freely across the world's surface. 

With the invention of the airplane, the importance 
of navigation increased. Pilots had to be fully cogni- 
zant of the principles of navigation if they were to 
fly safely from one point to another. 

Modern man still utilizes the earlier methods of 
navigation. A man on foot is still guided by familiar 
landmarks, but as mobility increases, the need for 
more extensive navigation aids grows. Automobile 
drivers reciuire markers and road signs. Ship captains 
are equipped with improved maps, compasses, and 
radios. Airplane pilots are supplied with their own 
maps and charts, and with electronic aids. The ancient 
types of navigational aids are still in use but with 
modern improvements. 

This chapter will discuss air navigation, define it, 
and describe four of its forms which are applicable 
to flight. 

What Is Navigation? 

Navigation is the science or art of conducting or 
steering a vessel, i.e., a boat, car, or airplane, across 

or through a medium, such as land, water, or air. It 
refers to man's ability to journey on or over the sur- 
face of the earth. 

Air navigation, then, is a science which determines 
geographic position and maintains a desired direction 
in the air with respect to specific positions and direc- 
tions on the ground. Aerial navigation is not unlike 
sea navigation in many of its problems and methods. 
It differs from sea navigation because the speed of 
the aircraft is many times that of a ship, and the 
effects of air currents on an aircraft are more critical 
than the effects of sea currents on a ship. 

Forms of Air Navigation 

Pilots, in the early days of flight, flew their aircraft 
for only short distances and at low altitudes. Flight 
was easily directed by referring to known landmarks, 
such as rivers, roads, and railroads. As science im- 
proved airplanes, longer flights at higher speeds and 
higher altitudes were possible— if the pilot could be 
freed from his continuous visual search for familiar 
guideposts. Because the airplane was now capable of 
flying under a variety of conditions (over water, over 
poorly-mapped terrain, in adverse weather conditions, 
and at high altitudes), improved navigational facili- 
ties were developed. 

The four common types of air navigation are: 
(1) pilotage, (2) dead reckoning, (3) radio, and 
(4) celestial. 

Pilotage. This form of air navigation is performed 
by locating landmarks on the ground and then match- 
ing them to a chart of the territory over which the 
airplane is flying. 

Dead Reckoning. This form of air navigation is 
performed by determining the direction to point the 
aircraft, prior to the flight. After the correct heading 
is calculated, considering compass errors and wind 
drift, the compass is the primary navigational aid used 
to keep the airplane traveling in the correct direction. 
Dead reckoning involves distance and speed problems 


which determine the length of time required for the 
aircraft to arrive over a destination. 

Radio Navigation. This form of air navigation is 
performed only if the aircraft is equipped with radio 
equipment. This equipment is used to determine posi- 
tion in flying a desired course over any part of the 
United States and over most of the world. Hundreds 
of ground transmitting stations have now been erected 
for extensive use in air navigation. 

Celestial Navigation. This form of air navigation is 
performed by observing angular reference to the sun, 
stars, and moon. 

A pilot rarely uses only one form of navigation. 
Usually a combination of these four methods is prac- 
tised to provide an accurate method for following a 
course. Before going into more detail, it may be well 
to cover some of the principles of map making. 

Position, Direction, and Distance 

Position, direction, and distance are the funda- 
mentals of navigation. Although the earth is not a 
perfect sphere, for the purposes of navigation it is 
considered to be spherical. The earth can be likened 
to a spinning ball which has an imaginary axis pass- 
ing through its center from the North Pole to the 
South Pole. (Figure 89.) 

Position. The Equator is an imaginary line around 
the earth midway between the North and South Poles. 
Imaginary lines, on a globe or map of the earth, 
drawn parallel to the Equator are called parallels of 
latitude. Lines perpendicular to the plane of the Equa- 
tor are meridians or lines of longitude. The meridian 
which passes through Greenwich, England, is called 
the prime meridian. 

These parallels and meridians form coordinates 
which make it easy to locate any position on the 
earth's surface north or south of the Equator and 
east or west of the prime meridian in degrees, minutes. 


Figure 90 — Lines of Longitude 

or seconds of latitude and longitude. (Figures 90 
and 91.) 

Direction. When the airplane is moving about in 
a familiar area where north, east, south, and west are 
known, direction is very simple. But to fly an airplane 
over a long, unfamiliar route presents the problem of 
keeping the airplane headed in the right direction; 
consequently, a system for expressing direction is 
needed. (Figure 92.) 

In navigation, direction is expressed in degrees, 

aO MP ^O^ 


Figure 89 — An Imogincry Axis through the Center of the Eorth 

Figure 91 — Lines of Lolitude 


Figure 92 — Latitude and longitude coordinates are similar to street and avenue intersections. 

Figure 93 — The direction from any given point on the eortli's surface fo any given point on the earth's surface is always measured as a 
certain number of degrees from north. 


clockwise from north. North is 360 degrees; east, 90 
degrees; south, 180 degrees; and west, 270 degrees. 
The direction from any given point on the earth's 
surface to any given point on the earth's surface is 
always measured as a certain number of degrees from 
north. (Figure 93.) As an aid to navigation, the 
Compass Rose has been devised to act as a graphic 
portrayal in determining direction. (Figure 94.) 

The path which an airplane intends to follow over 
the earth is called a course. When the direction of 
the course is measured from true north, it is called 
true course. True course may be determined on navi- 
gational charts by measuring the angle between the 
course line and the closest meridian, since all merid- 
ians are also true north lines. 

In plotting a true course, a line drawn on a sphere 
must be arced to follow the curvature of the earth. 
This line will be the shortest distance between two 
points, since it would be a section of the great circle 
which would divide the earth into two equal parts. On 
a flat surface, such as a map, this line will appear to be 
straight for short distances, but direction must be 
re-measured at appro.ximately every 3 degrees or 4 
degrees of longitude to avoid flying a straight line 
rather than the shorter, circular line which conforms 
to the shape of the earth. 

Distance. Distance can be expressed in many dif- 
ferent units. In air navigation, either a statute mile 
(5,280 feet) or a nautical mile (6,080 feet) is used. 
The nautical mile is now used more frequently, since 
one nautical mile is equal to one minute of arc at the 
equator and on all the lines of longitude. Either one 


or the other unit should be used when solving air 
navigational problems in order to avoid confusion and 

Maps and Charts 

A map is a diagram representing all or any portion 
of the earth's surface, and a map especially designed 
for navigation is called a chart. A chart used for air 
, navigation will indicate outstanding features of both 
I land and water as well as all radio stations. The pilot 
will use the chart to keep track of the airplane's posi- 
tion, and to measure the direction of the course and 
the distance between the point of departure and the 

It would be difficult to draw a chart large enough 
to represent the entire United States and at the same 
time present landmarks which are required for air 
navigation. The United States, therefore, is divided 
into 87 sections, each of which is represented on a 
chart. (Figures 95 and 96.) 

A globe, which is a true representation of the earth's 
surface and which is large enough to show detail 
necessary for navigation, would be far too bulky to 
be carried in the aircraft. Consequently, a projection 
of the earth's spherical surface is printed on a flat 
surface for more convenient use. 

Since the earth is a globe, it is impossible to draw 
a flat map of the world that is accurate as to shape, 
size, and scale. The earth's surface cannot be repre- 
sented on a flat surface without distortion. Distortion 
is better understood if one takes an orange, cuts it in 
half, then peels it carefully so that the skin comes off 
in one piece. Now try to flatten out the piece of skin 
without either cracking or stretching it, i.e., distorting 
it. It can't be done. Maps and charts of small areas 
have the least amount of distortion, but distortion 
cannot be entirely avoided. In. map making, many 
systems have been devised to control and minimize 
distortion, depending upon the use of the map. 

The exact position of any point on the earth can be 
found by the use of astronomy. Nearby points or 
features may then be found either by surveying or by 
aerial photography. The map is then made by draw- 
ing the geographic featiu-es on a framework of merid- 
. ians and parallels known as a graticule. The process 
involved in the construction of the graticule is called 
projection. Once the graticule is drawn, features may 
1 be plotted in their correct position with reference to 
the meridians and parallels. If a light bulb were 
inserted inside a transparent globe which showed the 
earth's features, including the meridians and lines of 
parallel, and these features were projected upon a 
flat surface, a picture would appear which would be 
very similar to the features of the globe but the pic- 



Figure 95 — Sectional Chart 









Joint civil and military 


Landing area 

Heliport (Selected) 

^ o 

2427 L 48 

Airport of entry 

278 119.5 126.2 
257.8 122.7G 


L-LightJng c 

Aerodromes with hard-surfaced 
runways at least 1500 feet long 

All recognizoble runways, including some which moy be closed, are shown for visual identific 


Elevation in feet 00 

Lighting (See below)t L 

Length of longest runway S 

in hundreds of feet 
-ol tower transmitting frequencies, 250 

119.5 126.2 257.8 3053 122. 7G guard(except 122.5Gnot shown). 

voilable Sunset to Sunrise 'L- Lighting ovoiloble Sunset to Sunrise on pri< 
first, followed in order by primorv VHF locol control, primory military VHF and UHF, and non st. 
When facility or information is tacking, the respective charocter is omitted or replaced by o dash. 

Aerodromes with hard-surfaced 
runways at least 1500 feet long 

U: Indicates • 

nay be omitted 

eronouticol advisor 

when same as 

' station licensed I 

Elevation in feet 
Lighting (See below)t 
Normally sheltered 
take-off area 
Length of longest rL 
in hundreds of feet 

r request (L)- Lighting available port of night only 
d guarding frequencies 


00 L S250 


learest town 


a\ advi 

. operoting on I 23.0 mc ore shown in the Remarks column 


Rotating light -ft- Flashing light |W.t 

Rotating light (With floshing code) ie Marine light 

Rotating light (With course lights) '"' -^ 

Flashing light Fl -tr 

F-fixed Fl-flashmg Dec -occulting Alt-olternqtmg Gp-groi 
Marine alternating lights ore red ond white unlesi 


W-white G-gteen B-blu 
! lights o 


indicoted. Man 

Facilities have voice unless indicated "I 
All radio facilities are printed in 
such as tower frequencies, radi 


o voice " All Marine Radiobeacons and Racons are without 
blue with the exception of certain LF/MF facilities 

ranges and radiobeacons. which are printed in magenta. 

Radio range [Without voice), 

(Two lettef identilic 

Marine radiobeacon 


Radio broadcasting station 


20m & 30m-40ni 


1. nondirectionaL 
(With voice' 

Outer marker 

(Shown when con 

radiobeacon _QLOMc 

ponent of airway system) 


, LOM , 

—••[359 EW -^ 

cation station- _G> .^FORT WORTH 


MESA GRANDE ^^' t\ea<iy line 

ection used as reporting point 

Figure 96 — Standard Syfnbols Used on a Sectional Chart 

ture would be distorted; the smaller the section taken 
out of the picture, however, the less the amount of 

Most aerial navigation charts are made from a 
Lambert Conformal Conic Projection. This may be 
thought of as a projection upon the surface of a cone 
which intersects the earth along two parallels of lati- 
tude. The axis of the cone coincides with the axis of 
the earth. (Figure 97.) A straight line drawn on the 
chart coincides with a great circle and is the shortest 
distance between two points. 

Charts or maps are made to specified scales. For 
instance, one inch on a map may represent eight miles 
on the ground. This presents no problem as long as 
the scale is clearly shown for each map. 

The Coast and Geodetic Survey of the Department 
of Commerce now publishes the aeronautical charts of 
the United States. The two most commonly used 
charts are the Sectional and Regional Charts. The 
Sectional Chart covers a smaller area, gives more 
detail, and is used for shorter flights. The Regional 
Chart covers a larger area with less detail, and usually 
is used for longer flights. 

Plotting a Course 

To plan a flight, a pilot must first obtain a chart (or 
charts) of the section of the country over which he 
intends to fly. To obtain a true course heading on this 
Lambert Chart, he draws a straight line from the 
departure point to the destination. He then places 


Figure 97 — Method of Obtaining a Lambert Projection 

a protractor so that its midpoint covers the intersection 
of the true course hne and any one of the meridians 
about half way between the destination and the 
departure point. Zero degrees on the protractor is 
ahgned with this meridian, and the true course head- 
ing is read at the point where the true course hne 
intersects the outside scale on the protractor. The 
angle between the true course line and the meridian 
which it intersects represents the angle of direction 
from true north, i.e., the North Pole. (Figure 98.) 


The pilot knows, however, that the magnetic com- 
pass, by which he steers, does not point to the North 
Pole but to the magnetic pole which is located in 
northwestern Greenland. To compensate for this error, 
the pilot must calculate the amount of magnetic varia- 
tion. In the United States, the amount of magnetic 
variation fluctuates from 25 degrees East in the State 
of Washington to 22 degrees West in the State of 
Maine, with degrees running through the Great 
Lakes south to Florida. These lines of magnetic vari- 

Figure 98 — Measuring a True Course line with Protractor 


to* IS- 

Kf !■ rf 5" KC «■ 20' 

/ — 

1 — 


.<•-— ~— "-^^^^^ 


4- 5- 0- 

Figure 99 — This diagram shows the agonic ond isogenic lines of 

ation error are indicated on aeronautical charts and 
are known as Isogonic lines (Figure 99.) 

To correct for a magnetic variation of 10 degrees 
East, for example, the pilot will subtract 10 degrees 
from his true course degree heading. The degree 
setting, after correction for variation, is called the 
magnetic course heading. The pilot will add 10 de- 
grees to his true course heading if the magnetic varia- 
tion is 10 degrees West. 

The airplane itself also creates magnetic fields which 
disturb the compass. These magnetic interferences are 
called deviation errors and they, too, must be cor- 
rected. To discover the amount of deviation error 
for a particular airplane, the aircraft is placed upon 
a Compass Rose with no error. This Compass Rose 
is usually painted on a concrete taxi strip away from 
the buildings of the airport. The compass of the air- 

plane is then compared with the Compass Rose and 
the difference between the two is the deviation error. 
This deviation error is recorded on the aircraft's com- 
pass deviation card and placed near the compass. 
From this, the pilot knows how much error he must 
allow before he obtains a correct compass reading. 
Briefly, the pilot uses the following formula to deter- 
mine compass course: 

True Course ± Variation = Magnetic Course 
Magnetic Course ± Deviation = Compass Course 

(TC)± (V) = (MC) ±(D) = (CC) 

Wind Drift Correction 

An airplane in the air has no more attachment to 
the ground than a ship has to the bottom of the ocean 
when sailing free. The air mass, in which the aircraft 
flies, moves over the surface of the earth at varied 
velocities. The air masses attempt to push the aircraft 
in the direction they are moving. The pilot wishing 
to fly over certain ground references must not let the 
air mass carry him in the wrong direction. Therefore 
he must compensate for wind drift in order to fly his 
intended track or course. (Figure 100.) 

A pilot receives infonnation about the amount of 
wind and the direction of the wind from a weather 
station. With this knowledge, he can correct his true 
course to a true heading by using either a computer 
or a wind triangle. (Figure 101.) 

When the pilot has organized and solved the many 
navigational problems relative to his flight, he will 
usually put this data on a form called a "flight log" 
or a "flight planning sheet," which he will carry with 
him during the trip. (Figure 102.) 

After checking the weather information and plot- 

Figure 100 — (Left) — Heading on oirplone directly olong its course 
without regord for wind direction or velocity will generally result in 
the airplane drifting off course. 

(Right) — Heading Ih 
which the w 


plane a definite amount 
II concel out the 


:tion from 
effect on the 

Figure 101— A Typical Wind Triangle 

ting his intended course, the pilot will inspect his 
aircraft (See Chapter 4) and will then be ready for 
takeoff. He may decide to use only one certain form 
of navigation, but more likely he will use some com- 
bination of the four forms. 

Pilotage Navigation 

The six steps in planning a pilotage flight are: ( 1 ) a 
true course line is drawn between departure point 
and destination; (2) the angular direction of the true 
course line is measured at the mid-meridian; (3) the 
course line is marked in segments of 10 or more miles, 
depending upon the size segment appropriate to the 
speed and range of the airplane; (4) landmarks along 
or near the route are designated as check points to be 
used to check heading and to determine ground 


speed; (5) prominent terrain features are selected 
along either side of the course and at the destination 
and are called brackets; and (6) compass course is 

In flight, the five steps to be followed in navigating 
by pilotage are: (1) fly direct to the first check point 
and take up the compass heading; (2) check wind 
drift; (3) correct heading; (4) determine elapsed 
time between check points and note ground speed; 
and (5) maintain a continuous scrutiny of the course 
flown, by use of check points and brackets. 

Pilotage is used for short flights in slow aircraft. 
Normally the pilot will use this form of navigation 
at an early stage of his training. 

Dead Reckoning Navigation 

If a pilot flies over an area that is sparsely settled, 
wooded, desert, or lacking in conspicuous landmarks, 
he will be unable to use pilotage. If his airplane has 
no radio equipment, he must depend upon dead reck- 
oning to reach his destination. 

The pilot, by using either a computer or a wind 
triangle, determines the amount of drift and calcu- 
lates the compass heading he must fly to reach his 
destination. He also estimates the time en route. After 
he is airborne, and over the departure airport, he 
turns to his predetermined heading, checks the time, 
and flies until his estimated time en route has expired. 
At this point, if his calculations are correct, he should 
find himself over his destination. 

A combination of pilotage and dead reckoning can 
be employed very successfully and is used more fre- 
quently than is any one system alone. These two forms 
















































Figure 102 — Contact Flight Log 


of navigation do not depend upon radio assistance 
for any portion of the trip. 

Radio Navigation 

The first aeronautical radio aid to navigation was 
a two-way communication system which linked the 
airplane to the airport. The pilot was thereby kept 
infoi-med of weather conditions en route and could 
also receive other information of value to him. Later, 
directional radio equipment was developed, which 
enabled pilots, while in flight, to determine the direc- 
tion to specific radio stations. 

The entire United States is covered with a vast 
system of airways, similar to highways, which are 
controlled by the federal government. Along these 
airways, spaced at appropriate distances, are radio 
stations which continually transmit signals. These air- 
ways ( radio roads ) , which the pilot follows, are called 
beams, radials, or tracks. (Figures 103 and 104.) 

If Very High Frequency radio (omni station) is 
the primary navigational aid on the airway, it is called 
Victor Airway. When Low Frequency radio is the 

primary electronic aid, the airways are colored air- 
ways, i.e., red, green, blue, or amber airways. 

Radio navigational charts are now available, which 
locate the radio transmitters. By using radio naviga- 
tion, a pilot can fly directly to an airport without ever 
seeing the ground. This is common procedure during 
days when clouds obscure the vision of the pilot. 
Pilots who fly in adverse weather should have an 
instrument rating. Without special instrument train- 
ing, only the foolhardy attempt to fly when the ground 
cannot be seen. 

Radio Transmission. Radiating electro-magnetic 
fields which travel long distances are called radio 
waves. Radio waves vary in frequency from about 
10,000 cycles to many million cycles per second. 

To avoid the use of many digits, when referring to 
frequencies, two units of frequency are used. One 
thousand cycles equals one kilocycle (Kc), and one 
million cycles equals one megacycle (Mg). 

A radio system consists of a transmitter, which 
broadcasts the radio waves through a transmitting 
antenna, a receiving antenna, and a receiver which 
converts the radio waves to voice signals. (Fig- 

Figure 103 — Radio Facility Chart 




'\2 TACAN 


/y LF/MF Range with simultane 
V^ Voice Signal Capab.hty 
>V LF/MF Range wilhoul simultan. 
V^ Voice Signal Capability 


r LMM Beacon 

anO'Consol Statu 
steal Broadcast S 
Marker Beacons 


at above or below 




ected treq or Chan 


Official Time Zone 


International Boundary 

sory Reporting Poi 



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4-* ♦-* f *-♦ 4-* ^jgg Boundary 


i ^ 


^,^ g^ ^ Boundary of Area Charts 

-___ Mileage between Compulsory 

Q]] Reporting Points and /or QT) 

, Designates char 
and /or MOCA v 

^otf Airways^ 

aster Serv 


P, than facilities /J, 

r Minimum Crossing Altitude r 
/ (MCAl / 



35 Mileage to Facility 

VOR Changeover Points 
(Not shown at mid-point locations) 

i to Fa 



Air Defense Identilicat 
Zone (ADIZ - CADIZ) 


5 depicted within this boundary-) 

Rp.t.icled Area 


ted A 


Warning Area 

Danger Area ICanad 
t Indicates inlorm 




■■B» NOTAM'- ind 



ion by 

NOTAM Areas w 

1 inci 

de L. 


14.500 tt . or floe 
operating lime 

ed by 



Military Clin 















Figure 104 — Radio Facility Chart legend 



Figure 105 — The obove illuslrales o 2 

ure 105.) Radio signals may be transmitted in a non- 
directional manner (Figure 105) or in certain speci- 
fied directions, thus forming beams or radials by which 
pilots can navigate. (Figure 106.) 

The two most commonly used frequency bands are 
the Low Frequency (L/F) band, ranging from 200 
Kcs to 400 Kcs, and the Very High Frequency (VHF) 
band, ranging from 30 Mgs to 300 Mgs. The VHF 
band is more popular, since this group of frequencies 
is not affected by electrical disturbances such as 
thunderstorms, which create static. L/F radio naviga- 
tional equipment is still very common but is being 
replaced rapidly with VHF equipment. 

The L/F transmitting station consists of four towers 
and four antennas. One signal only is transmitted from 
each tower. Two of the towers transmit the letter "N" 

Figure 106 — Directional Radio Trans 

( — ) and the two opposing towers transmit the let- 
ter "A" (--). (Figure 106.) 

Where the two signals meet or overlap, a solid hum, 
called a beam, is produced. This beam is directed 
along an airway and extends out to meet a beam from 
another station. A pilot can fly a certain heading along 
the beam and listen to the signals. The signals will 
tell him whether he is on the beam, or to the left or 
to the right of the beam. (Figure 107.) 

Since aircraft normally fly from airport to airport, 
radio transmitting stations are usually constructed 
near the airport. Each station sends its signals over 
a specified frequency and also transmits an identifica- 
tion signal in Morse Code; e.g., Springfield, Illinois, 

transmits the letters "S" (---) "P" ( ) "I" (--) 

to identify itself. 

Automatic Direction Finder. Another radio aid to 
navigation is the Automatic Direction Finder. This 
equipment can be tuned to certain Low Frequency 
stations and to standard broadcasting stations. 

A receiving antenna that automatically swings to- 
ward the transmitting station is employed. Attached 
to the antenna is a small electric motor that will rotate 
when the antenna rotates. This motor is in phase, 
electrically, with a similar motor attached to a needle 
located in the cockpit of the plane. Consequently, 
when the antenna rotates, this needle will rotate until 
it points directly toward the transmitting station. The 
rotating needle, which moves over a Compass Rose 
painted on the surface of the dial, can move 360 de- 
grees—always pointing in the direction of the trans- 
mitting station. (Figure 108.) 

Visual Omni Ran^e (VOR). The most widely used 

. Seven Mile ^^ 
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■Addyston !r5te=^^/\ /AX' '^P^'i/O^ 

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*-\ LUNKE 
(Oper by Cit 
AS LKA ^-- lT\Afrel 


V 128 N r^-;;! 


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flew Richmond 

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ILenoxburg VJj, 






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V 44 r 


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Brooksiille J 

V 174- 

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Figure 107— Part of a Sectional Chart Showing Four Directional Beams Transmitted by a low Frequency Station 





form of the radio navigational aids by commercial 
and private pilots is the Very High Frequency Visual 
Omni Range. Air traffic increased in the past decade 
to such an extent that navigational aids were in- 
adequate to handle the flow of traffic. To solve this 
problem, VOR (Visual Omni Range) was developed. 

VOR is a navigational aid that eliminates many of 
the deficiencies found in previous equipment, such as 
static due to atmospheric disturbances, interference 
from mountains, and a limited number of beams or 
courses to the station. 

Instead of four courses, only, to the station, VOR 
provides 360 courses to or from an omni-range station. 
All VOR stations are located on Victor Airways. 

The Omni Range is designed to operate within a 
frequency band of 112-118 megacycles. It produces a 
pattern of courses from the station similar to the 
spokes of a wheel, with the station representing the 
hub. These spokes are known as radials and are num- 
bered or identified by their magnetic direction from 
the station. Beginning at North, which is the 360- 
degree radial, they are numbered clockwise around 
the station. 

To use VOR, the aircraft must be equipped with an 
Omni (VHF) radio. This Omni radio has two un- 
usual features, i.e., the communication feature which 
permits the pilot to talk directly with the persons, if 
any, who are tending the station, and the navigation 
feature which enables the pilot to determine on which 
radial he is flying, thereby giving him the compass 
course the aircraft must fly in order to reach the sta- 
tion. (Figure 109.) 

To use the Omni range, the pilot first tunes in the 
desired station on the frequenctj selector (1) and 
identffies the station by its transmission of a three 
letter code; e.g., Minneapolis Omni would be identi- 
fied as "M" (--) "S" (---) "P" ( ). 

Figure 108 — The Rolaling Needle of the Aulomalic Direction Finder 

Figure 109 — Aircraft VHF Tronimitter and Recei' 


The pilot then rotates the course selector ( 2 ) manu- 
ally until the needle (3), which will move from side 
to side, is squarely in the center. He then reads, from 
the course selector, the course he must fly to reach 
the range station. The course selector will indicate 
the course either to the station or the course from the 
station, depending upon the position of the to-from 
indicator needle. 

After this orientation has been completed, and the 
pilot has turned the aircraft to the compass course 
indicated by the course selector, he must keep the 
needle centered by searching for the heading that will 
keep him on the radial. (When the aircraft is to the 
left of the radial, the needle will point to the right, 
or toward the radial. When the aircraft is on the 
radial, the needle will center. When the aircraft is 
to the right of the radial, the needle will point to 
the left.) 

There are numerous other aids for radio navigation, 
but those that have been covered are the most popular 
types used by private pilots today. 

Celestial Navigation 

In celestial navigation, position on the earth's sur- 
face is determined by reference to the heavenly bodies. 
During daytime flights, the sun is used as a reference, 
and at night the moon, planets, and stars are used as 

The accuracy of celestial navigation depends upon 
the skill of the navigator, the accuracy of his intru- 
ments, and the prevailing weather conditions. 

The items of equipment required for celestial navi- 
gation are: (1) a sextant, for observing celestial 
bodies; (2) a watch with a second hand; (3) an air 
almanac, for locating the position of the celestial 
bodies; and (4) numerical tables, for computing the 
line of position. 

A celestial navigator no longer needs to be an 

expert mathematician. Modern methods have simpli- 
fied this type of navigation to the point where anyone 
who can add or subtract can figure his geographic 
position in a very few minutes. The mathematics for- 
merly required has been eliminated through the use 
of numerical tables. 


Navigation refers to man's ability to journey on or 
over the surface of the earth, and air navigation is a 
science which determines geographic position and 
maintains a desired direction in the air with respect to 
specific positions and directions on the ground. 

Position, direction, and distance are fundamentals 
of air navigation. Position is expressed in degrees and 
minutes of longitude and latitude. Direction is ex- 
pressed by the angular difference, in degrees, between 
a specific heading and "north," or 360 degrees. Dis- 
tance is expressed in terms of nautical or statute miles. 

Maps and charts designed for aerial navigation will 
indicate outstanding terrain features as well as radio 
and other electronic aids. Most aerial navigational 
charts are made from Lambert Conformal Conic 

In plotting a course from the departure point to 
the destination, a pilot must determine: (1) direction, 
(2) distance, (3) speed, (4) magnetic variation, and 
(5) wind drift corrections. 

There are four common types of air navigation: 
( 1 ) pilotage— locating landmarks on the ground and 
matching them to a chart of the same area; (2) dead 
reckoning— determining the direction, speed, and dis- 
tance prior to takeoff; (3) radio— determining position 
by use of electronic equipment; and (4) celestial- 
observing the angular reference to the sun, moon, and 
stars. Each of the above listed navigational methods 
requires specific techniques. Varying weather con- 
ditions and pilot ability determine the method to be 
employed for a particular flight. 


1. Why is navigation important to any means of 

2. What is air navigation? 

3. What form of air navigation is performed by ob- 
serving angular reference to the sun, stars, and 

4. How does pilotage differ from dead reckoning? 

5. How is direction measured on a map? 

6. What is a great circle? 

7. Explain how compass heading is derived, and 
what is the difference between compass heading 
and compass course? 

8. How does the movement of an air mass over the 
ground effect an aircraft in ffight within the air 

mass? How is this effect corrected? 
9. What is radio navigation? 

10. What are the two most common radio frequency 

11. What advantage does a pilot have using a VHF 

12. Explain briefly the fundamentals of VOR. 

13. List the equipment necessary for celestial navi- 

14. How many degrees of direction are there on the 
earth's surface? 

15. Is true north the same as magnetic north? Ex- 

Chapter O Meteorology 


Figure 110 — The Atmospheric Regions or levels of the "Oceon" of 
Air Surrounding the Earth 

Because weather affects man directly, it has be- 
come his most common topic of casual conversation. 
Droughts, rainy seasons, and unusual weather con- 
ditions, such as excessive heat waves and cold spells, 
directly control the type of food man buys, the clothes 
he wears, his plans for a weekend of tennis or ice 
skating, his summer vacation period, and the trans- 
portation systems he uses. 

The advent of the airplane and the approach of 
the Aerospace age has caused the science of meteor- 
ology and weather forecasting to become even more 
important to larger numbers of people. Of all the 
many courses of study that are included in aviation 
training, meteorology— the study of the earth's atmos- 
phere—is one of the most important. 

The Atmosphere 

Surrounding the earth, held tightly to it by gravity, 
and rotating with it, is a huge ocean of air called the 
atmosphere. Although it extends upward many miles, 
our common weather occurs only in the lowest layer 
called the troposphere. The troposphere is a relatively 
thin layer, its height varying from season to season, 
but on the average is about 30,000 feet at the poles 
and 60,000 feet at the equator. The next layer above 
the troposphere is the stratosphere. For the most part, 
weather does not occur in this layer although some 
rather heavy turbulence is occasionally encountered 
by high-flying airplanes. Temperature remains rela- 
tively constant, or may increase slightly, with increas- 
ing altitude. Above the stratosphere is the ionosphere 
which is important from an aviation standpoint be- 
cause it reflects some of the radio waves from com- 
munications and navigation facilities. 

Elements of Meteorology 

To understand weather, it is necessary to know cer- 
tain basic facts and theories about the more impor- 
tant meteorological elements which, when combined, 
make up the weather. 



Temperature, the measure of heat, is an important 
element of meteorology. Heat is transferred from the 
sun to earth by a radiation process called insolation. 
The sun's heat is not absorbed by the earth's atmos- 
phere but is transferred directly to the earth's surface. 
A small amount of heat is absorbed and stored in the 
surface. The remainder is then reflected into the 
atmosphere by radiation, convection, and conduction 

The air at the surface is heated by conduction— the 
transferring of heat by contact— and by radiation— the 
transferring of heat by wave motion. When this sur- 
face air is heated, it expands, becomes lighter than 
the surrounding air, and consequently rises into the 
atmosphere. This method of carrying heat upward 
into the atmosphere is called convection. The heights 
to which these convective currents rise depend upon 
the intensity of the heating and the stability of the air 
masses. Convective currents cause turbulence, cumulus 
clouds, and sometimes thunderstorms. The fact that 
the air is heated by the earth and not the sun directly 
explains why the temperature is highest at the surface 
of the earth and progressively colder as the atmos- 
phere is penetrated. 

When the sun's rays strike the earth's surface in a 
direct rather than an angular manner, more heat is 
produced on that portion of the surface and subse- 
quently reflected into the atmosphere. This phenom- 
enon accounts for the variety of climates on the earth 
and the changing seasons of the year. In addition, the 
amount of heat which is absorbed by the earth is de- 
pendent upon the character of the earth's surface. 
When the sun shines on water, the heat is distributed 
throughout the entire depth by the action of tides, 
waves, and currents. Therefore, a relatively greater 
amount of heat is absorbed by large bodies of water. 
On the other hand, because land is a poor heat con- 
ductor, land areas absorb a relatively small amount 
of heat in a shallow layer. Consequently, during the 
daytime, land areas reflect more heat into the air, 
causing considerable increase in temperature levels of 
the atmosphere, while large bodies of water reflect 
less heat into the air, and increase temperature 
levels very little. At night, the ground soon loses its 
small amount of stored heat and the air above it cools 
quickly. The water, however, having stored more heat 
during the day, consequently supplies it to the air 
throughout the period of darkness. This is why there 
is little change in temperature between day and night 
over oceans, while the change over land is consider- 
ably greater. 

Although land areas do not absorb large amounts of 
heat, different types of land surfaces do absorb it in 

Figure 111 — Strength of Convective Currents Varies According to the 
Ground Characteristics 

varying degrees. (Figure 111.) Barren areas of sand 
or plowed fields, for example, do not absorb as much 
heat as those areas which are covered with vegetation. 
Over these barren areas, then, the temperature differ- 
ence between day and night is greater than it is over 
the vegetated areas. 


Another meteorological element which must be 
understood is pressure— the weight of the atmosphere 
on earth. The highest pressure is at the earth's sur- 
face and it decreases as the altitude increases. More- 
over, at any given altitiide, the pressure constantly 
changes. At sea level, the average pressure is 14.7 
pounds per square inch. This amount of pressure will 
support a column of mercury 29.92 inches high in 
a barometer and is equal to 1013.2 millibars. In 
aviation technology, pressure is always reported in 
terms of inches of mercury or millibars of pressure. 

Differences in pressure over the earth's surface are 
caused by differences in the intensity of the heating 
of its surface by the sun. These differences in pressure 
will influence the movement of air. Generally speak- 
ing, air will move from areas of relatively high pres- 
sure toward areas of relatively low pressure. 


Water exists in the atmosphere in tliree different 
physical states: solid, liquid, and gas. As a solid it 
takes the form of snow, hail, ice-crystal clouds, or ice- 
crystal fog. As a liquid it is found as minute water 
droplets in clouds and fog, as drizzle, and as rain. 
As a gas it is known as water vapor. 

Under a constant pressure, warm air supports more 
water vapor than does cold air. The amount of water 
vapor in the air is measured in terms of relative hu- 
midity, i.e., the ratio between the amount of water 
vapor actually present in a specified volume of air at 
a given temperature and the amount of water vapor 
which this same volume of air is theoretically able to 
support. As air temperatures decrease, air's ability to 
support water vapor also decreases, and the relative 
humidity increases. If this cooling process continues, 




10,000 FT. 

Figure 112 — A Composite Drawing of the Principal Types of Clouds Showing the Approximate Levels at Which They Are Found 


a temperature is reached where the relative humidity 
reaches 100 per cent. Further coohng of the air then 
causes excess water vapor to be condensed into a 
hquid. When this event occiu-s, temperature has 
reached the dew point, and the liquid water, in the 
form of small droplets, will remain suspended in the 
atmosphere in the form of clouds. If condensation 
continues, the droplets grow too large to be suspended 
and fall to the earth. This is called precipitation. If 
the temperature within the cloud is above freezing 
(32° F. ), the precipitation will be in the form of rain, 
but if the temperature is below freezing, the precipi- 
tation will be in the form of snow. Condensation 
which occurs only at the earth's surface is called fog. 


As indicated in the discussion of moisture, clouds 
are formed when the air is cooled to the dew point 
temperature level. Clouds are divided into two basic 
categories— stratus and cumulus. 

When whole layers of air are cooled, the clouds 
which are formed appear as smooth stratified layers, 
i.e., stratus clouds. These air layers are cooled in two 
ways: (1) by cooler air moving into and mixing with 
the stationary layer of air; and (2) by the air layer 
rising to a higher altitude. When a layer of air rises 
in the atmosphere it also expands since there is a de- 
crease in pressure. This new expansion of air will, in 
turn, cause additional cooling. 

When individual currents of air rather than whole 
layers of air rise into the atmosphere and cool to the 
dew point temperature level, the clouds which are 
formed have a lumpy or billowy appearance, i.e., 
cumulus clouds. 

While there are only two basic cloud categories, 
there are many variations within each classification. 
For purposes of identification and weather analysis, 
all of the various cloud types are separated into four 
famihes: (1) high clouds; (2) middle clouds; (3) 
low clouds; and (4) clouds with vertical development. 
(Figure 112.) 

High Clouds 

Clouds which form above 20,000 feet are classed as 
high clouds and are divided into three basic cloud 

Cirrus clouds are the highest and thinnest of all the 
cloud types. Their average height is about 32,000 feet, 
and they are composed of ice crystals which have a 
silky or fibrous appearance. Cirrus clouds are not thick 
enough to shade the sun and they do not present any 
problem to flying. However, certain types of cirrus 
clouds will indicate approaching bad-flying weather. 

Cirro-stratus clouds reach an average height of 

28,000 feet. At this altitude they appear as thin, 
whitish sheets, either in patches or as a complete 
covering in the sky. These clouds do not shade the 
sun or moon but at times cause a halo to form around 
them. Ciro-stratus clouds are very thin and are also 
formed by ice crystals. Although they present no prob- 
lem to flying activities, if they follow cirrus clouds 
they may indicate the approach of a low-pressure area 
with its usual bad-weather conditions. 

Cirro-cumulus clouds appear as small white globu- 
lar masses or flakes at an average altitude of 22,000 
feet. They produce some slight shading of the sun but 
are thin enough so that they are not a problem to 

Middle Clouds 

Clouds with bases ranging from 6,500 feet to 20,000 
feet are classed as middle clouds and are divided into 
two basic cloud formations: 

Alto-stratus clouds appear as smooth, gray clouds 
which have light and dark patches that are caused by 
differences in thickness. When they follow cirro-stratus 
clouds into an area, they indicate approaching bad 

Alto-cumulus clouds appear in the form of large 
white or grayish globular masses. They are fairly thin 
and produce partial shading of the sun. 

Low Clouds 

Clouds with bases below 6,500 feet are classed as 
low clouds and are divided into three basic cloud 
formations : 

Strato-cumulus clouds form at an average height of 
6,000 feet and have an average thickness of about 
1,400 feet. When viewed from below, the clouds have 
a wavy appearance. They occur most frequently in 
winter and often persist for two or three days. 

Nimbo-stratus clouds are the clouds from which 
steady rain falls. These clouds are dark gray in color, 
which is an indication of considerable thickness. These 
clouds do present some flight problems. 

Stratus clouds appear in uniform layers. The thick- 
ness of these clouds varies immensely so that at times 
they appear as a haze in the sky and at other times 
they are very dark gray. Stratus clouds often appear 
with other types of clouds such as cumulo-nimbus and 
nimbo-stratus. They do produce precipitation in the 
form of drizzle. 

Clouds of Vertical Development 

Clouds formed by vertically rising air are classified 
as clouds of vertical development. The bases of these 
clouds generally range from about 1500 to 5000 feet 
above ground. 


Cumulus clouds vary in size from a small spot in 
the sky to a large dark cloud many thousands of feet 
in diameter and thickness. Their tops are dome-shaped 
with rounded protuberances. These "fair-weather" 
cumulus clouds are formed as a result of the intense 
heating of the earth's surface. As the earth heats the 
air directly above it, the warmed air rises; as it rises, 
it is cooled until it reaches the dew point temperature. 
When the column of air reaches the dew point tem- 
perature, the cloud is formed. 

Cumulo-nimbus clouds are cumulus clouds which 
have continued to grow in size until enough condensa- 
tion has taken place to produce raindrops. When the 
raindrops become too heavy to be supported by the 
convective currents— updrafts— the raindrops fall from 
the cloud. From below, cumulo-nimbus clouds look 
like large, dark cumulus clouds. The tops of cumulo- 
nimbus clouds may rise to altitudes of 50,000 to 60,000 


Since unequal heating of the earth's surface causes 
uneven heating of the atmosphere, the atmosphere is 
in constant motion. Where the earth is intensely 
heated, the warm air rises, forming an area of rela- 
tively low pressure. Surrounding air, which is colder, 
will move into this low-pressure area, become warmed, 
and rise, thereby making room at the surface for more 
air. This cycle of circulation is constantly operating 
across the entire surface of the earth. (Figure 113.) 
Within this primary circulation there is secondary 
circulation. Large masses of air move toward low- 

Figure 113 — The theoretical winds on an Earth of uniform and even 
surface would follow the pattern shown here (cross section on right). 

pressure areas and cause changes in weather across 
the surface over which they move. Within the air 
masses there are also circulation movements, but on 
a smaller scale. For example, a rising convective cur- 
rent from a plowed field will create a low-pressure 
area within the air mass itself. 

Circulation accounts for wind— moving air. Primary 
circulations determine the general globular wind di- 
rections. Moving air masses influence wind direction 
and velocity over smaller areas, and circulation move- 
ments within the air masses influence wind direction 
and velocity in an even smaller region. Generally 
speaking, good weather is associated with high-pres- 
sure areas and bad or stormy weather with low- 
pressure areas. Low pressure— bad weather is caused 
by air moving inward toward low-pressure areas meet- 
ing air which is at a different temperature. Mixing 
takes place, usually cooling the warmer low-pressure 
air or forcing the warmer air aloft where it is cooled. 
When the temperature of the warmer air reaches the 
dew point, clouds and, often, precipitation result. In 
high pressure— good weather, air will neither be mixed 
nor cooled since circulation movements are outward 
and away from the high-pressure area. 


Air masses are large bodies of air which are hori- 
zontally uniform in temperature level and moisture 
content. They are identified according to their source 
region and their temperatiu-e. An air mass which 
forms over water is called a maritime air mass and 
contains large amounts of water vapor. An air mass 
which forms over land is called a continental air mass 
and contains relatively small amounts of water vapor. 
Air masses which form in the arctic and polar regions 
are called arctic or polar air jnasses and those which 
form in the tropical regions are called tropical air 
masses. A cold air mass is "cold" if it is colder than 
the surface over which it is moving. A warm air mass 
is "warm" if it is warmer than the surface over which 
it is moving. For example, a mass of air which forms 
over Northern Canada and then moves quickly down 
over the Middle West would be classified as a Con- 
tinental Polar Cold air mass (cPk) because it was 
formed over land, in a polar region, and its tempera- 
ture is colder than the temperature of the surface over 
which it is passing. 

A front is the boundary zone between two contrast- 
ing air masses. When air masses are stationary the 
front is called a stationary front. When the air masses 
are moving, with a colder air mass replacing a warmer 
air mass, the front is called a cold front. When a 
warmer air mass replaces a cooler air mass, the front 


is called a warm front. Fronts are very important to 
flying activities because weather changes almost al- 
wa\s are associated with them. 

The preceding paragraphs have pointed out and 
briefly described some of the important meteorological 
elements of weather. The principles which were dis- 
cussed should help the student to understand better 
the physical phenomenon called weather. 

Elements of Weather 
Important in Aviation 

The weather elements to be discussed in this sec- 
tion are those which are of most importance to pilots. 
Every good pilot studies these elements when he plans 
a flight. 


Ceiling refers to the upper boundary of the air 
space between the earth's surface and the lowest cloud 
layer. More specifically, it is height measured to the 
base of the lowest layer of clouds which covers more 
than one-half of the visible sky. 

The ceiling is important to everyone who flies, but 
its importance varies, depending upon the qualifica- 
tions of the pilot and the type of equipment in his 
airplane. A certified pilot with an instrument rating 
is primarily interestetl in the ceiling at his destina- 
tion, since he is qualified to fly through clouds and 
poor weather conditions if his airplane is properly 
equipped. First, he must know if the ceiling is so low 
that he will have to make an instrument approach to 
the airport. Second, if he must plan to make an instru- 
ment approach, the height of the ceiling will partially 
determine the type of instrument approach it will be 
necessary to make. Third, if the ceiling is extremely 
low, so that there is no margin of safety, the pilot will 
probably land at an alternate airport rather than at 
his intended destination. 

A pilot who is not qualified to fly solely by reference 
to instruments or a pilot who is flying an airplane not 
equipped with the necessary instruments must rely 
on his visual ability to see the ground. This means, 
of course, that the pilot must stay out of clouds. This 
pilot is interested in knowing the ceilings en route as 
well as the ceiling at his destination because he needs 
to know if he has enough room between the earth 
and the clouds in which to fly his airplane safely. 


Visibility is spoken of in terms of miles of distance 
a pilot is able to see horizontally outside of clouds. 
Visibility is important because the more restricted it 
is, the closer airplanes will be before they can see each 

other. Also, the more restricted the visibility, the 
harder it is to navigate by pilotage and the harder 
it is to keep track of the attitude of the airplane. 

Just as with ceiling, a person capable of flying and 
navigating by instruments is not too concerned with 
visibility except at his destination. At his destination, 
visibility will determine whether or not the pilot must 
make an instrument approach. If an instrument ap- 
proach is necessary, the visibility will have some bear- 
ing on the t\pe of approach which he uses. If visibility 
is too restricted, i.e., a safety margin does not exist, 
the pilot will either decide not to go or will land at 
an alternate airport. 

Four common restrictions to visibility are ( 1 ) fog, 
(2) precipitation, (3) haze, and (4) smoke. 

Fog varies in intensity but it can, and often does, 
cut visibility to zero or to 1 16 of a mile, which is too 
restricted even for safe instrument landings. Fog oc- 
curs most often during the nighttime hours when the 
sky is clear and when the earth is radiating its heat 
into space; then, as the cool ground cools the air above 
it to the dew point temperature level, fog may form. 
This type of fog usually dissipates soon after the sun 
rises in the morning. 

Precipitation does not generally reduce visibility to 
the degree that fog does; however, there are certain 
exceptions. Snow, for example, can erase in-flight for- 
ward visibility entirely, even though it is not heavy. 

Figure 114 — Pilot's forward visibility in snow can approach zero even 
ttiough snow is not tieovy. 


JC^'-X^/i^-^^ ^^ 

Figure Hi — Avoiding Convectt^e Turbulence by Flying above Cumulus 

(BilOV/ ABOUT 20 MPH) 


Figure 116 — Surface obstructions cause eddies and other irregular 
wind movements. 


O O 9 O <J ^ 

\^ 'i^ \ COID CAIM AIR 

Figure 117 — Turbulent Air at the Boundary between Calm, Cold Aii 
Below ond Moving, Warm Air Above 

Figure 118 — Cleor-Air Turbulence in the Wake of on AircrofI 

(Figure 114.) When the ground is covered with snow 
and when the snowfall is heavy, it produces visibility 
conditions equal to zero. Rain from thunderstorms can 
occasionally be so heavy that the pilot is unable to 
see the horizon. 

Although haze is caused by impurities in the air, it 
does not usually reduce visibility limits to less than 
3 to 5 miles. However, it causes the light from the sun 
to be diffused so that visibility may be less than one 
mile looking toward the sun while it is considerably 
more looking away from the sun. 

Smoke causes the same effect as haze and is a prob- 
lem only in low altitudes over industrial areas. Smoke 
is most detrimental to visibility, however, when it is 
mixed with fog or haze. 


Turbulence refers to irregular movements of the 
air— gustiness. Generally turbulence is not a serious 
hazard to flight, but it does produce uncomfortable 
conditions. In some cases it can be hazardous, but only 
if it is unexpected. 

The most common cause of turbulence is unecjual 
heating of the earth's surface on a clear day. (Figure 
111.) The resulting convective currents rising from 
the earth's surface to the atmosphere cause the flight 
path to be rough, up to a certain altitude. This alti- 
tude is usually marked, if there is sufficient moisture 
in the air, by cumulus clouds. Above the cumulus 
clouds, the air is smooth. (Figure 115.) 

Other types of turbulence are caused by wind blow- 
ing over irregular terrain, (Figure 116) by wind 
shear— wind from difi^erent directions or of different 
speeds moving side by side— (Figure 117) and by the 
slipstream of airplanes. (Figure 118.) The latter is a 
problem only on takeoffs and landings when one air- 
plane follows too closely behind another. 

The thunderstorm produces the most violent of all 
turbulences because it is composed of a series of 
strong updrafts and downdrafts existing side by side. 
(Figure 119.) It is not uncommon for updrafts with 
speeds of 30 feet per second and downdrafts with 
speeds of 15 feet per second to exist side by side. 
Thunderstorms are hazardous, however, only if the 
pilot is not prepared for them and if he does not have 
his airplane moving at a safe flying speed. Only ex- 
perienced instrument pilots flying stable airplanes 
completely ef|uipped for instrument flight attempt to 
fly through thunderstorms. Generally the pilot will do 
all he can to avoid them. If thunderstonns are 
scattered, the pilot can go around or between them. 
If he must go through a line of storms, he will try to 
pick the least violent areas through which to fly. 
The pilot can do this by visually observing the storms 


■The above shows the three stages in the life cycle of a thunderstorm, (a) cumulus stage; (b) mature stage; and (c) dissipating stage. 

ate direction of drafts 

Figure HP- 
Arrows indicate direction of drafts 

or, if he is operating in the clouds, observing them by shape of the wing, thereby reducing the amount of 
radar. Hft the wing can produce; and (4) increases the total 

weight of the airplane. 

It is quite common for water to exist in the atmos- 
phere in a liquid state at freezing or below freezing 
temperatures. If this water is disturbed, however, it 
will immediately freeze. This disturbance, when cre- 
ated by an airplane, will cause the liquid to solidify 
and freeze onto the airplane itself. Occasionally rain 
will fall through layers of air that are at freezing 
temperature levels. The surface skin of an airplane 
flying through these same air layers will also be at 
freezing temperature levels. As the airplane strikes 
the raindrops, they immediately freeze to the air- 
plane. (Figure 120.) Icing is a flight hazard be- 
cause as ice collects on the airplane it (1) increases 
drag, which tends to slow the forward speed of the 
airplane; (2) changes the shape of the propellers, 

thereby reducing their effectiveness; (3) changes the Ponei 

Figure 120 — Rime Ice, with Some Glaze Ice, on Outer Right Wing 



S I150M250[4R-K fl32f/58/56 1 17|/993/ 

©55/ RB05 eV©R18VR32 


Sky cover symbols ire In ascending 
order Figures preceding symbols are 
heights In hundreds of (eel above slatlon. 
Sky cover Symbols are: 
0=Clear: Less than 1 sky cover 
(D^Scallered 1 to less than 6 sky cover 
(I) = Broken 6 to 9 sky cover 
® .Overcasl More than 9 sky cover 
- =Thin (W hin ptihvcj iu ihi jh..n >>nih.iK 
-X=Parttal Obscuration 1 to less than 1.0 sky 1 

1 sky hidden by precipitation 



Reported In Statute Miles 



' Llttht — LlRht (n 


D =Dust H^Haze BD ^Blowing Dust 

F =Fog I F= Ice Fog BN ^Blowing Sand 

G F= Ground Fog K = Smoke BS = Blowing Sro» 


IN - E t S -. W 

i«' NKE .-V ESE 

«' NE V SE 

•-*' ENE f V SSE 
Sp«ed In Knots follows direction 
+ Indicates "Gusty" Peak speed follows "gusty" sign 

t / SSW -•N WNW 

^ SW S NW 

-»/ WSW i \ NNW 






NOTE: Since January 1, 1964, wind directiot 
which is always a zero, is omilled. Winds hi 
a G is added to denote gusty conditions. 

Figure 121 — Key to Aviation Weather Report 

In airplanes which are not equipped with anti-icing 
or de-icing equipment, icing weather conditions must 
be avoided. With fully equipped airplanes, however, 
icing conditions will not suspend flight operations if 
de-icing equipment is properly used. 

Weather Information Available to Pilots 

Weather information is available to the pilot in two 
forms— reports and forecasts. Reports are compiled 
from visual observation of the existing weather condi- 
tions. From these reports and with a complete knowl- 
edge of the physics of the atmosphere, meteorologists 
can accurately forecast weather conditions for the next 
several hours. 


Approximately every hour on the hour, 24 hours a 
day, at weather bureau stations and Federal Aviation 
Agency (FAA) communication stations throughout 
the country, trained personnel observe certain weather 
conditions and report them, via teletype, to all the 
other stations in the network and also to any airport 
or agency that subscribes to the teletype service. 
(Figure 121.) Since these reports are made so fre- 
quently and since they report existing weather condi- 
tions from more than 500 stations, hourly sequence 
reports are very valuable to pilots in flight planning. 


Pilots encountering unusual weather conditions dur- 
ing flying report this weather to the nearest FAA 
communication or weather bureau station for distribu- 
tion to other pilots by teletype or radio. Pilot reports 
are important from two standpoints : ( 1 ) a pilot actu- 
ally flying through the weather can supplement the 
information gathered by the observer on the ground 
who cannot always determine the exact weather con- 
ditions existing at flight altitude; and (2) pilot reports 
serve as gapfiller reports on unobserved weather be- 
tween stations. 


At six-hour intervals, observers at each of the 
weather bureau's stations report the existing weather 
at their station to a central station. At the central sta- 
tion, these reports are used to make a map which 
shows the weather throughout the entire country. This 
weather map is then sent to each weather bureau 
station via a facsimile machine. (Figure 122.) Actu- 
ally, several maps are made and distributed, which 
show existing conditions both at the surface and at 
several specified altitudes above the surface. 


Weather bureau stations also periodically check the 
winds aloft. (Figure 123.) This wind information is 


\ \ /~rv'~'^ ^^~ 


\ '^'---S^^^..^.^ 


/y^^^o / 







r^i^^i^--^'^> ^--^x^ 

\^ ^v!^^ 





These reports describe observed upper wind conditions (or each thousand foot levei 
up to 10,000 feet above Mean Sea Level. Larger altitude intervals are used above 
10,000 feet. 

•cha""i^ °^ i 2S^ WIND AT 10,000 FT. MSL. — / 

nmu ni iu,uuu ri. moL. 

WIND AT 12,000 FT. MSL 

Directions are in TE>fS of degrees (true); speeds in KNOTS. 


01 309 




Station is Chattanooga, Tenn. 

Time of observation, in Greenwich Civil Time (1500 GCT) 

Surface wind from 130 degrees at 9 knots (Not Included by all statior 

Wind at 2000 feet M.S.L. from 80 degrees at 12 knots 

Wind at 3000 feet M.S.L. from 50 degrees at 15 knots 

(Note odd altitudes have no indicator for altitude) 
Wind at 4000 feel M.S.L. from 360 degrees at 16 knots. 
Wind at 5000 feet M.S.L. from 340 degrees at 21 knots, etc. 

UPPER WIND REPORTS indicate winds observed at a particular timt 

Figure 123 — Key to Report of Winds Aloft 

sent, via teletype, to all other weather bureau stations 
and is useful to the pilot as it enables him to select 
the best altitude at which to fly. 


Every six hours major weather bureau stations fore- 
cast the weather for their particular area for the next 
12-hour period. (Figure 124.) This forecast includes 
expected clouds, weather, icing, and turbulence. These 
forecasts are distributed by teletype to all airports 
and to all other agencies who subscribe to the service. 


Every six hours, at each of the weather bureau sta- 
tions, trained forecasters forecast the weather for 
twelve hours in advance. (Figure 125.) These fore- 
casts are also distributed by teletype just as are the 
area forecasts. 

The above are the more important reports and fore- 
casts which are made available to pilots. There are 
many methods and instruments used by the personnel 
who gather and disseminate the weather data, but to 
describe them is beyond the scope of this chapter. 
There are still many unanswered questions in meteor- 
ology. Instruments, such as radar, have helped to solve 
many of the puzzles. It is expected that the break- 
through into space will result in the solving of many 


Meteorology, the scientific study of the atmosphere, 
is extremely important inasmuch as weather directly 
affects all people, particularly those who fly. 

The atmosphere consists of many parts. Of great- 
est current importance is the troposphere— that part of 
the atmosphere which is next to the earth's surface. 
It is within the troposphere that man exists, pilots do 
most of their flying, and changes in weather conditions 
take place. 

Temperature is one of the most important elements 
of meteorology. Differences in the temperature of the 
air result from differences in the heating of the earth's 
surface by the sun. This causes varying climatic con- 
ditions in the world and changing weather conditions 
within climatic regions. Changes in air temperature 
cause clouds and precipitation, since cool air will not 
support as much water vapor as warm air. When 
cooling of warm moist air takes place, condensation 
occurs at a certain temperature level called dew point. 
Condensed water vapor results in clouds or fog. 
Further cooling and condensation of water vapor may 
result in precipitation. 

There are four categories of clouds: high, middle, 
low, and clouds of vertical development. The two 
basic types of clouds are stratus and cumulus with 
variations within each of these types. 









Area forecast for period 7 a.m. to 7 p.m. Central Standard Time for Minnesota, North Dakota, 
South Dakota. 

Clouds and Weather. Heights mean sea level unless noted. Conditions in a bu mile squall line 
zone through southeastern Minnesota mostly 6000 foot overcast but visibilities briefly 2 to 4 
miles and ceilings near 2000 feet above ground within heavier thunderstorm area. This squall 
line will move southeastward about 25 miles per hour and dissipate by about 10 a.m. Central 
Standard Time. Stratus overcast 500 to 1000 feet above ground in northeastern Minnesota will 
clear by middle of the morning but local areas of low broken clouds 600 to 1200 feet above 
ground will persist until about noon along the slow moving cold front lying from International 
Falls to Huron at 5 a.m. and is stationary from there westward to beyond Rapid City. Broken 
clouds at 10,000 feet to 12,000 feet will be general in central and western portions of the 
Dakotas with a few high level thunderstorms developing in the late afternoon. 

Icing. Light to occasionally moderate icing in clouds above 12,000 feet except locally heavy 
in thunderstorm areas. Freezing level height 12,000 feet to 14,000 feet. 

Turbulence. Moderate to heavy in thunderstorms. 

Outlook. 7 p.m. Sunday to 7 a.m. Monday. Thunderstorms in central and western Dakotas will 
end by early afternoon but another squall line will develop from northeastern Minnesota to the 
southeastern corner of South Dakota by 7 p.m. that will move eastward about 25 miles per 
hour with locally severe conditions and then dissipate shortly after midnight. Elsewhere un- 
restricted visibilities and no clouds below 10,000 feet above mean sea level. 

Figure 124 — Area Aviation Forecast and Interpretation 



TERMINAL FORECASTS contain intormation for specific airports on ceiling, 

SIGMET odvises airmen in fliqhl of severe or extreme 

cloud heights, clouci amounts, visibility, weather concJilion ond surface wind. 

weather conditions potentially hazardous to all aircraft. 

They are written in a forni similar to the AVIATION WEATHER REPORT. 


CEILING Identified by Ihe leller "C" 

ClOUD HEIGHTS; In hundreds ol feel above the station 
CLOUD LAYERS Stoted in order of height 
VISIBailY: In statute miles, but omitted If over 8 miles 

flight of weother conditions of less severity than SIGMET 
but which may be hazardous to light aircraft. Both types 
of advisories are broadcast by FAA on NAVAID voice 

SURFACE WIND: In knots but omitted when less than 10 



WINDS ALOFT FORECASTS provide a 12-hour forecast 

C.5o|c„U.,i00- b.o>....o„d, /3^Jc..o.,...W..,...=.J 

of wind conditions at selected flight levels. Temperatures 

C1506K ,,V,b"°„ °° .U,",'i".'l. 

aloft ore included for selected stations. 

20a)C70®\30* <>'''"0 '000" ev.-co... lu.loce 


5-2030J 5,0C!0«Sl 200%l30,l-i. 

AREA FORECASTS are 12-hour forecasts of cloud and weather conditions, 
cloud tops, fronts, icing and turbulence for an area the siie of several states. 
A 12-hour OUTLOOK is added. Heights of cloud tops, icing, and turbulence 

.,* I,m„,.o.... 

10-2540/3| 10,000 MSI .,„di,o»»o-oiMU.., i,«„.o..„»j-c 

ore above SEA LEVEL. 

PILOTS report in-fliqht weather to nearest FSS. 




Figure 125 — Terminal Forecasts and Interpretation 

The atmosphere is constantly in motion. This motion 
is called circulation. Primary circulation occurs on a 
world-wide scale; secondary circulation occurs on a 
more localized scale within the boundaries of the 
primary circulation. Circulation is caused by unequal 
air pressure, which, in turn, is caused by unequal heat- 
ing of the earth's surface. 

Huge masses of air, in which temperature and mois- 
ture characteristics are uniform, are constantly moving 
across the surface of the earth. Boundaries between 
these air masses are called fronts. The leading edge 
of a cold air mass which is replacing warm air is called 
a cold front. The leading edge of a warm air mass 
which is replacing cooler air is called a warm front. 
Generally, cold fronts produce turbulent weather con- 
ditions, such as thunderstorms in summer, over a rela- 
tively narrow area along the front. Warm fronts, on 
the other hand, produce less turbulent weather, but 
over a much wider area along the front. 

The most important weather conditions from a 
pilot's viewpoint are ceiling, visibility, turbulence, 
and icing. 

Ceiling is the upper boundary of the airspace be- 

tween earth and the base of the lowest level of clouds 
covering more than one-half of the sky. Ceiling meas- 
urements tell the pilot how much space he has in 
which to fly and still maintain visual contact with the 
earth's surface. 

Visibility is the maximum horizontal distance which 
a pilot can see when flying outside of clouds. 

Turbulence is the result of irregular currents of 
air. A ride in an airplane under these conditions can 
be rough and uncomfortable in varying degrees. Tur- 
bulence may be caused by convective currents, wind 
blowing over irregular terrain, wind shear, or an air- 
craft slipstream. 

Ice will form on an airplane if it is flying through 
visible moisture and if the temperature of this mois- 
tiire or the temperatvu-e of airplane's surface skin is at 
or below freezing. Icing on an airplane increases drag 
and weight and decreases thrust and lift. 

The United States weather bureau maintains more 
than 500 stations throughout the country. These sta- 
tions observe and forecast the weather and make their 
reports and forecasts available to pilots. 



1. In which part of the atmosphere does common H. 
weather occur? 

2. What is temperature? 12. 

3. Describe briefly how the atmosphere is heated. 13. 

4. What is convection? 14. 

5. Over what kind of surface will there be the least 15. 
change in temperature between night and day? 16. 

6. What is relative humidity? 

7. Which is capable of containing more vapor, warm 17. 
air or cold air? 

8. Describe briefly how clouds form. 18. 

9. Name the clouds that produce rain. 

10. What kind of weather is generally associated 19. 

with low pressure areas? 20. 

Give two characteristics of a continental polar 
air mass. 

What is a cold front? 
What is a warm front? 
What is a ceiling? 

What are four common restrictions to visibility? 
How much of the sky is covered when a layer of 
clouds is described as scattered? As broken? 
How does an accumulation of ice on an airplane 
efi^ect its flight characteristics? 
List the sources of weather information avail- 
able to pilots. 

How long a period is covered by area forecasts? 
How often are terminal forecasts made? 

Chapter 10 Air Traffic Control and Communications 

Figure 126 — Airport Control Tower 

A few years ago, when relatively few airplanes were 
flying, airplane traffic at the larger air terminals, such 
as New York, Chicago, and San Francisco, was no 
problem. Now a highly developed system of air traf- 
fic control is required to control airplanes flying 
along the civil airways as well as those arriving or 
departing from the air terminals. The purpose of this 
chapter is to discuss briefly air traffic control methods 
and radio and radar procedures. 

Air Terminal Problems 

Every transportation control system— land, water, 
and air— regulates in some measure the traffic which is 
en route, as well as the traffic at points of arrival and 
departure. A large railroad terminal, the center for 
converging routes, schedules incoming and outgoing 
trains by switches and signals. Buses and automobiles 
depend upon safety rules and traffic signals to reach 
their destination. Ocean liners observe maritime law 

as they sail the sea lanes from port to port. 

The airplane presents a different problem. Although 
its passage is also controlled by rules and signals, the 
airplane operates at various heights, on invisible aerial 
highways, and often unseen. In addition, it is unable 
to stop en route. A train can halt on its rails, an auto- 
mobile or bus can stop on the road; a steamer can 
anchor offshore or in midstream; but an airliner, even 
when it has been slowed to approach an airport for 
landing, is still traveling between 100 and 230 miles 
per hour. Jet airliners especially complicate the prob- 
lem, because they operate at the higher speeds and 
because at low altitudes, they consume fuel at an 
extremely high rate. Another unique problem of air 
traffic control is caused by the airplane's need to rely 
on humans using radios and other electronic instru- 
ments to fly safely through clouds, rain, fog, and dark- 
ness on invisible pathways from one airport to an- 
other, rather than on steel rails or concrete highways. 
Aircraft are aided by controllers in Air Route Traffic 
Control ( ARTC) centers and in airport control towers. 
(Figure 126.) 

Aircraft Communication 

Since the radiotelephone and the omnirange VOR 
have achieved such widespread use and importance, 
the pilot, to fly safely, must have expert knowledge 
of his radios and of their operation. The pilot must re- 
ceive, acknowledge, transmit, navigate, and comply 
with instructions which he receives through radio- 
telephone transmissions. His life and the lives of 
others may depend on the accuracy with which he 
carries out these instructions. 

In radiotelephone communication, the accuracy 
with which messages are received depends largely 
upon the clearness of the speaker's voice. Loud talking 
into the microphone is unnecessary and makes recep- 
tion difficult. A normal tone of voice is used, with the 
microphone being held close to the mouth but slightly 
at an angle. (Figure 127.) In radio conversation it 
must be remembered that engine and static noises are 


in competition with the spoken word, even though 
modern high frequency radio equipment does ehmi- 
nate much of the static caused by atmospheric con- 
ditions. It is important to be concise and businesslike 
and to know what is to be said before beginning the 

To hmit the possibility of error in the transmission 
of names or difficult words, a standardized phonetic 
alphabet has been devised to identify individual 

"A" - Alfa 
"B" — Bravo 
"C" - Charlie 
"D" - Delta 
"E" - Echo 
"F" — Foxtrot 
"G" - Golf 
"H" - Hotel 
"I" — India 
"J" - Juliette 
"K" - Kilo 
"L" — Lima 
"M" — Mike 

"N" — November 
"O" — Oscar 
"P" - Papa 
"Q " — Quebec 
"R" — Romeo 
"S" — Sierra 
"T" - Tango 
"U" — Uniform 
"V" — Victor 
"W" - Whiskey 
"X" - Xray 
"Y" - Yankee 
"Z" - Zulu 

In the case of numerals, an exaggerated pronunciation 
is emphasized. Numerals "9" and "5," which can be 
easily confused, become "ni-ner" and "fi-yiv." All num- 
bers are transmitted as numerals or digits except in 
the case of an even hundred or thousand; then the 
word "hundred" or "thousand" is used. When trans- 
mitting numbers, extreme care is required since num- 
bers are used to give time, altitude, altimeter setting, 
headings, and weather information. 

To avoid confusion, flight time is based on the 24- 
hour Greenwich Meridian clock. The 24-hour clock 
eliminates the necessity of saying a.m. and p.m. When 
transmitting time, the first two numerals always desig- 
nate the hour and the last two the minutes. Midnight 
is "0000," spoken as "ze-ro ze-ro ze-ro ze-ro"; noon is 
"1200," spoken as one two ze-ro ze-ro"; 7:45 a.m. is 
"0745," spoken as "ze-ro sev-en four five"; and 5:28 
p.m. is "1728," spoken as "one sev-en two eight." 
The last two numerals, indicating minutes, are ordi- 
narily used in traffic control procedure when no mis- 
understanding can result. For instance, both the pilot 
and the control tower operator or communications sta- 
tion operator know that it is about 10:15. Giving in- 
structions to the pilot, the operator says, "Time is one 
five." If it were 10:46, the time would be given as 
"four six." 

Call signs identify the transmitting or receiving sta- 
tions. When calling airport control towers, the expres- 
sion "Tower" is used, and when calling a flight service 
station, the word "Radio" is used. A control tower is 

designated by the name of the airport or city at which 
it is located, e.g., "Midway Tower" or "Peoria Tower." 
Flight service stations are called by adding the word 
"Radio" to the name of the station, e.g., "Chicago Area 
Radio" or "Peoria Radio." 

Airplane call signs consist of words, letters, num- 
bers, or a combination of tliese factors. Private air- 
planes use the name of the manufacturer and the 
registration (N) number, e.g., "Cessna November 
three four sev-en niner five." Commercial transport 
call signs may be the name of the airline and the 
flight number, e.g., "American four" (American Air- 
lines, Trip 4). 

A set of procedure words and phrases now in use 
for communication between the airplane and the 
ground station or another airplane, and their mean- 
ings, are given below: 

Word or 




Say again 
I say again 



Message received and meaning un- 

Will comply with instructions. 
Let me know you have received and 
understood my message. 
I will repeat. 

Transmission ended; I expect a re- 

Communication ended; no reply ex- 

Every radiotelephone message has three parts: (1) 
the call; (2) the text; and (3) the ending. 

The call includes: (1) the call sign of the receiving 
station; (2) a connecting word or phrase; and (3) the 
call sign of the transmitting station. 

Airplane: "Springfield Radio, this is Beechcraft three 

four ze-ro six bravo. Over." 
Station: "Beechcraft three four ze-ro six bravo, 

this is Springfield Radio. Over." 

The message is then transmitted and the communi- 
cation ended. If there is no possibility of confusion, a 
shortened call form may be used after communication 
has been established. 

Airplane: "Springfield radio, this is Beechcraft three 
four ze-ro six bravo. Request current altim- 
eter setting. Over." 

Station: "Beechcraft three four ze-ro six bravo, al- 
timeter setting too ni-ner ni-ner. Over." 

Airplane: Ze-ro six bravo. Out." 


ophone for Radio-Telephone 

Such radio communications procedure, when care- 
fulh- followed by both pilots and ground communica- 
tion stations, provides an extremely effective link be- 
tween the airplane and the ground. This procedure 
also permits large traffic centers to handle hundreds 
of airplanes each day with a minimum amount of 
trouble and a maximum amount of safety. New sys- 
tems of electronic signalling are expected to speed up 
and simplify communication procedures; some may 
eliminate voice communication entirely. 

Airport Traffic Control Tower 

At smaller airports, where the traffic is not heavy, 
the pilot can approach the aiiport directly, inspect the 
traffic circle for other airplanes which may be circling, 
observe field conditions, wind direction and velocity, 
and then fit into the pattern and make his final ap- 
proach and landing. Most small airports have a "Uni- 

com" system, which is nothing more than a small radio 
station that transmits and receives on one frequency 
only. This frequency is 122.8 Mcs. In case there is a 
tower, 123.0 Mcs is used. Unicom is used only as a 
private aviation communication system and is only an 
advisory station. At these smaller airports, it is the 
pilot's responsibility to choose the active runway, 
maintain separation from other airplanes, and make 
a safe landing. 

At busy airports, however, the above procedure 
would create dangerous and delaying conditions. For 
this reason, the airport traffic control tower is given 
the responsibility for: (1) directing all incoming and 
outgoing traffic; (2) permitting airplanes to enter the 
traffic pattern at the proper time; (3) controlling the 
approach and landing sequence on specified runways; 
(4) giving taxiing and takeoff instructions; and (5) 
reporting field and weather conditions. (Figure 128.) 

The Control Tower, in today's aviation activities, is 
far more important than it was ten years ago. Many 
towers in high-density traffic areas, such as Chicago, 
control so much traffic that it is necessary to divide 
tower responsibilities into special areas, i.e., (1) 
Ground Control, which controls all aircraft from the 
ramp or parking area to just short of takeoff position, 
and from the active runway, after landing, to the ramp 
or parking area; (2) Tower Control, which controls 
all takeoffs and landings; (3) Approach Control and 
Departure Control, which controls aircraft just prior 
to the landing procedure and immediately after take- 
off. The work of Approach and Departure Control is 
particularK- important during instrument flight con- 

The areas that are particularly important to the 
pilot flying under Visual Flight Rules (VFR) condi- 
tions are those of Ground Control and Tower Control. 
When an aircraft is departing from a busy airport, 
taxi instructions, wind direction and velocity, runway 
in- use, field condition, altimeter setting, clearance to 
taxi, and local traffic information are transmitted from 
Ground Control. At the point just prior to taxiing onto 
the active runway, and after making the pre-takeoff 
check, the control of traffic switches from Ground 
Control to Tower Control. The Tower then clears the 
aircraft for taxiing onto the active runway and for 

When approaching the airport, upon first contacting 
the Tower, the pilot reports his location relative to the 
airport. The Tower then gives the pilot the wind 
direction and velocity, the active runway, altimeter 
setting, field conditions, and the next "call in" or check 
point. When the pilot reports from the new check 
point, he receives his clearance to land, landing se- 
quence, and information on other traffic. After landing, 


Figure 128 Interior of on Airport Control Tower Showing the Tower Operator Giving Weather Information to an Aircraft in Flight. 

the pilot is instnicted by the Tower to turn off the 
active runway and to switch to Ground Control. It is 
extremely important that all directions be carefully 
obeyed as they are given by the particular control 
agency, and that all communications be brief and to 
the point. 

A Typical Radio-Phone Conversation 

Airplane: "Midway Ground Control, this is Beech- 
craft three four ze-ro six Bravo south ramp, 
ready to taxi, VFR departure St. Louis. 

Ground "Beechcraft three four ze-ro six Bravo, 

Control: cleared to runway two two left, wind 
southwest at one five, altimeter two niner 
niner niner, time one three ze-ro five 
Greenwich, ta.xi west on ramp and north 
on runway tliree six, hold short of runway 
two two left." 

Airplane: "Roger, ze-ro six Bravo." 

The pilot proceeds to the northeast/southwest run- 

way and, after checking engine and instruments, re- 
quests his takeoff clearance from the Tower Control. 
Airplane: "Midway Tower, this is Beechcraft three 

four ze-ro six Bravo, ready for takeoff. 

Tower: "Beechcraft three four ze-ro six Bravo, 

cleared for takeoff." 
Airplane: "Roger, ze-ro six Bravo." 

An aircraft should call the control tower when 
coming in for a landing under VFR conditions ap- 
proximately 15 miles from the airport. The following 
should be included: 

1. Geographical Position 

2. Time ( optional ) 

3. Flight altitude of the aircraft 

4. Request for information or clearance if pertinent. 


Airplane: "Midway Tower, this is Beechcraft three 

four ze-ro six Bravo. " 
Tower: "Beechcraft three four ze-ro six Bravo, tliis 

is Midway Tower. Go ahead." 


Figure 129 — Airport Control Tower Operator Manning a Light Signal Gun 

Airplane: "Midway Tower, this is Beechcraft ze-ro 
six Bravo, fifteen miles south, two five at 
three thousand landing at Midway. Over." 

Tower: "Ze-ro six Bravo, runway two two Left, 
wind southwest at one five, altimeter two 
niner niner two, report two miles south. 

Airplane: "Wilco, ze-ro six Bravo." 

When the pilot has reached a position two miles 

south of the field he renews contact with the Tower. 

Airplane: "Midway Tower, this is ze-ro six Bravo, 
two miles south." 

Tower: "Ze-ro sLx Bravo, you are number two to 
land. Call Tower on base." 

Airplane: "Roger, ze-ro six Bravo." 

The pilot enters the traffic pattern (Figure 88) and 

calls again as he turns onto his base leg; that is the leg 

before the final turn into the runway. 

Airplane: "Midway Tower, ze-ro six Bravo turning 

Tower: Ze-ro six Bravo, cleared to land." 

Airplane: "Roger, ze-ro six Bravo." 

After landing. Tower Control will clear the pilot 

from the active runway and request that he change 

to Ground Control, which will direct him to the park- 
ing or ramp area. 

Several points in the above typical conversation be- 
tween the Tower and the airplane should be explained 

at this point. Note that the Tower, in giving landing 
information to the incoming airplane, says, "Wind 
southwest at 15 knots, use runway 22." All runways 
are numbered according to their magnetic direction, 
e.g., when landing toward the east the compass will 
read 90 degrees and the approach will be over the 
west end of the runway which is marked with a large 
figure "9." In the above-mentioned example, since 
the wind is from the southwest, the aircraft will ap- 
proach for a landing over the northeastern end of 
the northeast/southwest runway. The magnetic head- 
ing will be 220 degrees— the figure "22" on the end of 
the runway. This same runway will be marked "4" at 
its southwestern end— 040 degrees will be the magnetic 

When flying from one area to another, there is nor- 
mally a change in barometric pressure. To make cer- 
tain that the altimeter in the airplane indicates the 
proper altitude, the barometric pressure corrected to 
sea level at his destination is radioed to the pilot. 
By changing the barometric pressure reading in his 
altimeter to conform with the newly received baro- 
metric pressure, the pilot is able to read his correct 

To receive clearance to land at large airports, air- 
planes carry two-way radios, i.e., a transmitter and a 
receiver, but at smaller airports, light signals may be 
used instead of radiotelephone communication. Fol- 
lowing this method an outbound airplane moves far 


Figure 130— An Air Rout* Traffic Control Cente 

enough out from the ramp or parking area to permit 
the Tower to see it. Using a light-projecting device 
(Figure 129) operated like a gun, the tower operator 
flashes a red light, meaning "hold your position," or 
a flashing green light, meaning "begin taxiing." Before 
turning onto the runway for takeoff, the airplane stops, 
faces the tower, and waits for another signal. In this 
position, a flashing red light means "clear the runway 
and hold your position," a green light signifies "per- 
mission to take off" or "continue taxiing," and a flash- 
ing white light means "return to the hangar line." 

Inbound aircraft receive their first signal during the 
approach leg; a red light means "do not land, continue 
circling the field," and a green light means "cleared to 
land." Acknowledgment of all light signals received 
while in flight is made by rolling the airplane slightly 
from side to side or by blinking the navigation lights. 

Air Traffic Service 

Airplanes en route under VFR conditions may fly 
at a minimum altitude of 500 feet, except over con- 
gested areas where at least 1,000 feet above the 
highest obstacle must be maintained. Under VFR con- 
ditions the same aircraft may follow a civil airway 
directly to its destination. A civil or federal airway. 

maintained by the FAA, is a 10-mile wide aerial 
highway free of dangerous obstacles. Radio navigation 
aids enable the pilot to guide his plane along these 

Since all airways are designated Air Route Traffic 
Control Areas, all traffic flying on Instrument Flight 
Rules (IFR) in these areas is controlled by the Air 
Route Traffic Control center (ARTC). (Figure 130.) 
The ARTC issues traffic clearances directly to planes 
in flight through direct communications, Omni radio 
stations, airport control towers, or approach and de- 
parture controls. ( Figure 128. ) 

When bad weather eliminates contact flight, pilots 
with instrument ratings fly along the civil airways at 
assigned altitudes and at known airspeeds, and arrive 
at their destinations at predetermined times. 

Between any two major cities there can be a dozen 
airplanes traveling in the same direction. To make 
certain that there are no collisions, these airplanes 
flying at different speeds are required to fly at different 
altitudes, which are assigned by the Air Route Traffic 
Control center. As an additional safety factor, air- 
planes are separated by a time interval at the takeoff 
point. Radar is also used in high traffic areas not only 
to separate traffic but to speed and vector its move- 


wrrioc. \jr uincv^iun 


















Figure 131 — Toble of Organization of Air Troffic Ser 

These services come under the control of Air Traffic 
Service. (See Figure L31) The primary responsibil- 
ities of the Air Traffic Service are to: 

A. Assist the administrator in developing the plans, 
standards, and systems for control of air traffic. 

B. Keep aircraft safely separated while operating 
in controlled space when on the ground, during 
take-off and ascent, enroute, or during approach 
and landing. 

C. Provide pre-flight and in-flight assistance serv- 
ice to all pilots. 

The specific functions of the three divisions of Air 
Traffic Service are: 


Supervises the operation of aircraft flying 
under Instrument Flight Rules (IFR) in con- 
trolled airspace. ( Long range radar which ex- 
tends outward to 200 miles and upward to 
60,000 feet, is used by ARTC centers to con- 
trol enroute traffic.) 


Supervise the operation of aircraft on and in 
the vicinity of airports. Approach and De- 
parture control use short range radar to con- 
trol incoming and departing aircraft. 


These stations have no control functions but 
are very important because they provide: 

A. Pre-flight weather briefings. 

B. In-flight following service. 

C. Local and area weather reports, changes 
in radio frequencies, operating condi- 
tions at certain airports, temporary air- 
port restrictions and similar notices of 
interest to airmen. 

Flight Plans 

Flight plans must contain pilot and airplane identi- 
fication, time and point of departure, proposed cruis- 
ing altitude and airspeed, proposed route, destination, 
estimated time of arrival, and the alternate airport to 
be used in an emergency. Flight plans are required 
for all airplanes operating on IFR. For safety reasons 
it is recommended that pilots flying VFR file flight 
plans on all cross-country flights. 

Instrument flight plan approval may be obtained 
from the appropriate Air Route Traffic Control center 
by filing it with the nearest center, tower, or com- 
munications station. The tower, station, or service will 
in turn request ARTC clearance. Although flight plans 
are normally filed while on the ground, filing a flight 


Figure 132 — A Typical Flight Plan 


plan or requesting a change in a fliglit plan while in 
flight is accomplished by contacting the nearest com- 
munications station or center for approval. Clearance 
will be relayed from ARTC to the pilot through the 
communications station or from the Air Route Traffic 
Control center. 

When a clearance is issued by an ARTC center it 
must be adhered to in all respects and at all times, 
except in an emergency. En route, the pilot must re- 
port flight progress to ARTC whenever he passes over 
a compulsory reporting point, such as an omni station. 
This progress report includes the following informa- 
tion: instrument flight plan, present fix or reporting 
point, altitude, time over the fix, next reporting point, 
and estimated time of arrival over next reporting 
point. This information is used by ARTC to keep 
the various instrument flights proceeding along the 
airways separated by both altitude and time. Air 
Route Traflic Control centers are linked by a teletype 
and direct interphone network with other airport 
towers, FAA communications stations, and military 
radio facilities. (Figure 131.) 

Typical Instrument Flight Procedure 

You, a qualified instrument pilot flying a D-18 twin- 
engine Beechcraft, are planning an instrument flight 
from Indianapolis, Indiana to Dayton, Ohio. Your first 
stop is at the weather bureau where you receive in- 
fonnation about present and forecasted weather con- 
ditions along your route of flight, at your destination, 

and at your alternate airport. You also get briefed on 
the icing levels and type of icing you may encounter, 
the estimated wind direction and velocity at your in- 
tended altitude, and special hazards or conditions, 
such as heavy thunderstorms or tornados, which you 
might encounter. Before you leave the weather bureau, 
you call the tower, radio, or Air Route Traffic Control 
center and file your proposed instrument flight plan. 
(Figure 132.) All IFR proposals should be filed at 
least thirty minutes prior to departure time. 

After filing your flight plan, you proceed to your 
airplane and perform an intensive preflight inspection, 
store and secure the baggage, load your passengers, 
make certain they fasten their safety belts and request 
that no one smokes until airborne. Secure the door, 
proceed to the pilot's compartment, and fasten your 
own belt before you start the engines. After starting 
your engines, but before taxiing away from the ramp, 
call Indianapolis Ground Control. 




"Indianapolis Ground Control, this is Twin 
Beechcraft eight ze-ro five eight Hotel, In- 
strument FHght (IFR), Dayton. Over." 
"Beechcraft eight ze-ro five eight Hotel, 
Runway three one, wind northwest at ten, 
altimeter two niner eight ze-ro, time two 
one four five Greenwich, taxi west then 
south on ramp, hold short of runway three 
"Roger, five eight Hotel." 

The aircraft is now cleared to just short of the 

__ fO flOHID* 

,- / 

.DAWN j'o" 



llii «'" LIBERTY 


I I u/uirci / 

Figure 133 — A Portion of a Radio Focility Chart 


take-off position on runway 31. In the next transmis- 
sion, Ground Control (if available) or control tower 
will issue the instrument flight clearance which they 
received from Air Route Traffic Control. This is the 
exact route to be followed after leaving the airport 
and reaching the "Clearance Limit," i.e., the farthest 
point along the route to which you are cleared. 

Ground "Beechcraft eight ze-ro five Hotel, this is 
Control: Indianapolis Ground Control, have your 

ATC clearance, ready to copy? 
Pilot: "Indianapolis Ground, five eight Hotel, 

ready to copy." 
Ground "ATC clears Beechcraft eight ze-ro five 
Control: eight Hotel to the Dayton Omni, via di- 
rect Fairground Intersection, Victor fifty, 
Dayton Omni, maintain five thousand, con- 
tact Indianapolis Departure Control one 
one eight point five after release from 
tower, right turn out of traffic, over." 

The pilot reads back the entire clearance to be cer- 
tain he understands. A shorthand method is used 
when copying the clearance: 

EXAMPLE: C 8058 H Day. 

D Fairground A, V-50 M 50, etc 
DepC 118.5 RT 
After copying and reading back the clearance, 
change the radio setting to the appropriate tower 
control frequency and call the tower: 
Pilot: "Indianapolis Tower, this is Beechcraft 

eight ze-ro five eight Hotel, ready for 
takeoff, over." 
Ind. "Beechcraft eight ze-ro five eight Hotel, 

Tower: this is Indianapolis Tower, cleared for 
takeoff, right turn out, contact Departure 
Control one one eight point five imme- 
diately after takeoff." 
Pilot: "Indianapolis Tower, this is five eight 

Hotel, Roger, out." 

After takeoff, make a right turn, start the climb to 
5,000 feet, and change to Departure Control,. Depar- 
ture Control now issues new headings, or directions, 
to reach the Fairground intersection. Since most ap- 
proach and departure controls have radar, they will 
give headings and vectors by radar. 

When you contact Indianapolis Departure Control, 
it should sound fike this: 


"Indianapolis Departure Control, this is 
Beechcraft eight ze-ro five eight Hotel. 
Over." Pilot: 

Ind. Dep. "Beechcraft eight ze-ro five eight Hotel, 
Control: this is Indianapolis Departure Control. Dayton 


Pilot: "Indianapolis Departure Control, five eight 

Hotel, off Indianapolis five ze-ro, estimat- 
ing Fairground Intersection five five, climb- 
ing to five thousand. Over." 

Ind. Dep. "Beechcraft five eight Hotel, Indianapolis 

Control: Departure Control, radar contact, main- 
tain heading ze-ro four five, report over 
Fairground Intersection this frequency. 

Pilot: "Five eight Hotel. Roger." 

Upon reaching the Fairground intersection, the pilot 
Avill initiate the call by saying: 

Pilot: "Indianapolis Departure Control, Beech- 

craft five eight Hotel, Fairground Intersec- 
tion five five, five thousand, estimating 
Dayton Omni three five, Destination. Over." 

Ind. Dep. "Five eight Hotel, Roger on your position, 

Control: contact Indianapolis Center one two four 
point niner immediately. Over." 

Pilot: "Indianapolis Departure Control, five eight 

Hotel switching to one two four point 
niner now. Five eight Hotel out." 

From now on, ARTC controls the flight and issues 
new clearances until the flight is turned over to ap- 
proach control at the destination. In this example the 
pilot is instructed to contact the center immediately 
and the conversation will then sound like this. 

Pilot: "Indianapolis Center, this is Beechcraft 

eight ze-ro five eight Hotel, Fairground 

Intersection. Over." 
Ind. "Beechcraft eight ze-ro five eight Hotel, 

Center: this is Indianapolis Center. Clearance. 

Pilot: "Indianapolis Center, five eight Hotel ready 

to copy." 
Ind. "Beechcraft eight ze-ro five eight Hotel, 

Center: contact Dayton Approach Control on one 

two five point seven, ten minutes west of 

Dayton Omni." 

The pilot would then report his new clearance and 
say "Roger. Out," but would be required to maintain a 
listening watch on this frequency 124.9 mc until he 
switches over to contact Dayton approach Control on 
125.7 mc. This call should be made 10 minutes prior 
to his estimated time of arrival (ETA) which was 
2235 Greenwich, so at 2225 Greenwich, he would say: 

"Dayton Approach Control, this is Beech- 
craft eight ze-ro five eight Hotel. Over." 


Approach "Beechcraft eight ze-ro five eight Hotel, 
Controh this is Dayton Approach Control. Over." 
Pilot: "Dayton Approach Control, five eight Hotel 

estimating Dayton Omni three five, five 
thousand, Dayton Omni clearance limit. 
Dayton "Beechcraft eight ze-ro five eight Hotel. 
Approach Clearance. ATC clears Beechcraft eight 
Control: ze-ro five eight Hotel to descend to and 
maintain three thousand and hold west 
on Victor fifty, right hand turns, one- 
minute pattern, report leaving five thous- 
and and expect approach clearance at two 
three one five Greenwich. Over." 

The following is a shorthand form which is used 
by the pilot to copy the clearance. 

C 8058H\jM^0, H W 

V50 RT 1 Min RL 50, EAC 15. 

The pilot reads the clearance back and proceeds to 
the omni station, descends to 3,000 feet and enters 
a race track pattern. At 2315 Greenwich Dayton Ap- 
proach Control issues a new clearance. 

Dayton "Beechcraft eight ze-ro five eight Hotel, 
Approach this is Dayton Approach Control. Clear- 
Control: ance. ATC clears Beechcraft eight ze-ro 
five eight Hotel for an ILS ( Instrument 
Landing System) approach to the Dayton 
Airport, report leaving three thousand and 
the Dayton Omni, contact Dayton Tower 
one one niner point five over Outer Marker 
inbound. Over." 
The pilot reads the clearance back and proceeds 
to follow instructions. In many terminal areas where 
approach control uses radar, the pilot would be vec- 
tored to the final ILS approach by radar. 

When the pilot arrives over the ILS outer marker, 
he contacts the tower and continues his approach. 
The tower will give him the latest altimeter setting, 
winds, and landing information. As soon as he breaks 
out VFR and has the runway in sight, he can tell the 
tower and they will then clear him to land and can- 
cel his Instrument Flight Plan. 

When the pilot has visually identified the airport, 
he immediately cancels his flight plan. He should do 
this because approach control will not clear any other 
aircraft for an approach until he has cancelled or 
safely landed. 

If the weather is so bad that the pilot does not 

see the runway until he is at minimum altitude, the 
flight plan is automatically cancelled without a re- 
quest when the airplane touches down on the run- 
way. In order to do this, the tower maintains direct 
communications with ARTC to notify them of the 
safe arrival. 


Air traffic is controlled by the federally-operated 
Air Route Traffic Control system and by the local field 
Control Tower. Air traffic arriving at or departing 
from a field is guided and directed by the Control 
Tower. After leaving the Control Tower's jurisdiction, 
all flights are controlled by the Air Route Traffic Con- 
trol (ARTC) system which separates flights by time 
and by altitude, to eliminate the possibility of col- 

Communication between ground stations and air- 
planes is conducted by radiotelephone. In order that 
such communication will be understandable, the pilot 
must refrain from using unnecessary words, must 
clearly indicate whether he is calling the "Tower," 
"Radio," or "Center," and must always identify his 

To expedite air traffic in the vicinity of the airport, 
the Control Tower operator is charged with assigning 
a landing sequence number to incoming planes. He 
also informs the pilot about the altimeter setting, the 
wind direction and velocity, the ground obstructions, 
and the other air traffic. Similarly, before takeoff, the 
Control Tower operator grants permission for air- 
planes to taxi to the proper runway and, finally, clears 
them for takeoff. 

Airliners and private airplanes equipped with a two- 
way radio must file a flight plan when flying cross- 
country under IFR conditions. This flight plan, when 
submitted to Air Route Traffic Control, indicates the 
takeoff time, destination, preferential route to be fol- 
lowed, altitude, airspeed, aircraft number, alternate 
ail-port, and pilot's name. It is frequently filed with 
the local Control Tower which relays it to ARTC. Air 
Route Traffic Control then lists the flight and surveys 
the route for conflicting air traffic. If there is no danger 
of collision with other flights, the flight plan is ap- 
proved and the pilot is given permission to take off. 
It is extremely important that the pilot radio his posi- 
tion over radio check points and that, upon landing 
at his destination, he notify the Control Tower oper- 
ator to close his flight plan. 



1. List the words which are used in the standard 
phonetic alphabet. 

2. When the 24-hour clock is used what time would 
it be at 1:00 a.m.? 3:15 p.m.? 12:00 noon? 
9:30 p.m.? 

3. What are the three primary responsibilities of 
Air Traffic Service? 

4. For what type of radio station is the word "tower" 
the call signal? The word "radio"? 

5. What are the parts of a radiotelephone mes- 

6. What are the functions of ARTC? 

7. In the absence of radio, how does a tower control 

8. Why should a pilot cancel his IFR flight plan 
as soon as he has the field in sight? 

9. What information do inbound and outbound 
pilots get from the tower when they are on a 
VFR flight plan? 

10. What facts must be included in a flight plan? 

11. What is the procedure for filing and receiving 
approval of a flight plan? 

Chapter 11 The Federal Aviation Agency 

In the early days of aviation when there were only 
a few thousand pilots and a few hundred airplanes, 
there were practically no regulations governing safety 
in flying. Airplanes, good and bad, were designed, 
assembled, and flown by anyone who wished to do so. 

After 1920, the number of airplanes and pilots mate- 
rially increased and, unfortunately, so did the number 
of accidents. Newspapers were constantly filled with 
stories of careless, untrained, or irresponsible pilots 
who had "cracked up," some with and some without 
passengers. During this period, the majority of the 
accidents occurred because pilots flew either in un- 
airworthy airplanes or in dangerous weather condi- 
tions. Another prominent cause for so many of the 
early crackups was the irresponsible pilot who at- 
tempted aerobatics in overloaded airplanes, flew under 
bridges, dived at football crowds and "showed off" in 

Government Regulations 

In order to prevent needless and tragic accidents. 
Congress, in 1926, enacted legislation which was de- 
signed to promote safety throughout the industry. 
Pilots were forbidden by law to carry passengers, give 
instruction, or otherwise earn their living by using an 
airplane until they had demonstrated flying proficiency 
and until they had passed written examinations which 
demonstrated their knowledge of Flight Regulations, 
Navigation, Meteorology, etc. In addition. Congress 
established standards for airplane and engine manu- 
facturing companies which prevented them from using 
unsatisfactory materials, unsound airplane designs, 
and faulty construction methods. 

It was logical that major control of flying activities 
should be assumed by the federal government; conse- 
quently, the Civil Aeronautics Administration was 
established in 1938. City, county, and even state 
boundaries are traversed so quickly that local law 
enforcement usually was impossible. For this reason 
it became essential that a minimum set of rules be 

established for use on a national as well as on a state 
or local level. However, because of the vast number 
of people required to enforce these federal regulations, 
state governments, in their own interests, cooperated 
with the federal government by policing aviation ac- 
tivities within their own borders. In 1944, the Model 
Aviation Act was prepared following a conference 
between federal and state aviation officials. This Act 
established a basis whereby state laws could be 
brought into conformity with federal regulations and 
with statutes of other states. 

Today, most states have special commissions or 
departments both to foster and to regulate aviation. 
Special aviation police, state police, and county and 
municipal department forces are used to enforce avia- 
tion safety practices. The majority of pilots are aware 
of their responsibilities and do not need policing. 
These pilots do nothing to jeopardize their own lives 
or the lives and property of others. Such men are part 
of the large majority who know that "There are old 
pilots and there are bold pilots, but there are no old 
bold pilots." 

Internationally, aviation activities operate within a 
framework developed by the International Civil Avia- 
tion Organization (ICAO), a department of the 
United Nations, with headquarters in Montreal, Can- 
ada. This organization deals on an international scale 
with the activities that are similar in nature to those 
sponsored by the Federal Aviation Agency on a na- 
tional scale. ICAO provides, operates, and maintains 
communication and navigational facilities, standardizes 
names, terminology, and systems of measurement, and 
promotes personal travel by helping to eliminate red 
tape in connection with passports, visas, and the like. 

Functions of the Federal Aviation Agency 

Federal promotion and regulation of civil aviation 
is controlled by two governmental bodies— the Federal 
Aviation Agency (FAA) and the Civil Aeronautics 
Board (CAB). 



ou of 







Figure 134 — Federal Aviation Agency Table of Orgonizotion 

The CAB is a quasi-judicial body composed of five 
members appointed by the President. The Board is 
principally concerned with the economic regulation 
of organizations engaged in public air transportation 
and accidents involving their aircraft. 

The FAA is assigned to the executive branch of 
the federal government by the Federal Aviation Act 
of 1958. On January 1, 1959, the Federal Aviation 
Agency assumed all duties and responsibilities former- 
ly handled by the Civil Aeronautics Administration, 
which had operated under the Department of Com- 

The function of the FAA is to regulate and pro- 
mote civil aviation and to provide for the safe and 
efficient use of the airspace by civil and military air- 
craft. The scope of this function is vast. Four general 
areas of activity are: (1) Control of both civil and 
military air traffic by making the air traffic rules, and 
in addition, by issuing specific instructions to specific 
aircraft under certain conditions of flight; (2) Pro- 
viding all ground facilities for traffic control as well 
as for navigation and communications between con- 
trolling facilities and aircraft; (3) Determining the 
qualifications and specifications to be met by all per- 
sons engaged in flight activities and all aircraft, then 
testing to insure that these standards are constantly 
met; and (4) Besearch and development for new 
methods and equipment. 

The FAA is headed by an Administrator. Two Dep- 
uty Administrators and three Associate Administrators 
are responsible to the Administrator for planning, di- 
recting, and coordinating all operations. 

The Deputy Administrators 

A Deputy Administrator has been appointed to co- 
ordinate FAA work on the supersonic transport pro- 
gram and to present research findings and recommen- 
dations to a presidential committee. 

The other Deputy Administrator, who serves as act- 
ing Administrator in the absence of the Administrator, 
is the general manager for FAA operations and is re- 
sponsible for coordination of activities of the Begional 
offices. He is also responsible for affairs of the FAA in 
Europe, Africa, and the Middle East, and the activities 
of the Bureau of National Capital Airports. 

There are seven Begional offices headed by Assist- 
ant Administrators who are responsible to the Deputy 
Administrator for the direction and execution of all 
programs in the field. 

Associate Administrators 

Three Associate Administrators direct and coordi- 
nate administration, programs, and development. The 
Associate Administrator for Administration advises and 
assists the Administrator in all matters concerning ad- 


ministrative management, security, budget, and per- 
sonnel. The Associate Administrator for Programs is 
responsible for air traffic service, systems maintenance 
service, and airport service. The Associate Adminis- 
trator for Development is responsible for aircraft de- 
velopment, installation of facilities, material service, 
research and development, which includes the Na- 
tional Aviation Facilities E.xperimental Center at At- 
lantic City, N. J. 

Federal Aviation Regulations 

The first few simple rules governing air traffic were 
third-dimension adaptations of maritime Rules of the 
Road. In the interest of aviation safety, however, new 
air traffic rules had to be developed as traffic in- 
creased to the point that both night and day opera- 
tions, in all kinds of weather, became common-place. 
Rapid expansion in other branches of aviation also 
necessitated additional regulations. Presently, there 
are Federal Aviation Regulations which cover almost 
all phases of aviation. In addition. Advisory Circulars 
are issued as necessary to cover short-lived rules or 
procedures, as well as for clarification of standing 
rules and procedures. Because of the large number of 
regulations and the high frequency with which they 
are changed to meet current needs, it is neither prac- 
ticable nor within the scope of this chapter to quote 
specific rules. The following index of the Federal 
Aviation Regulations will serve to illustrate the wide 
variety of activities presently covered by regulations: 


Part 1— Definitions and Abbreviations. 

Part 37— Technical Standard Orders for Materials, 

Parts, and Appliances. 
Part 39— Airworthiness Directives. 
Part 41— Airworthiness Operating and Equipment 

Part 43— Maintenance and Alteration. 
Part 45— Identification and Registration Marking. 

Subchapter D AIRMEN 

Part 61— Certification: Pilots and Instructors. 
Part 63— Flight Crewmembers Other Than Pilots. 
Part 65— Certification: Airmen Other Than Flight 

Part 67— Medical Standards and Certification. 

Subchapter E AIRSPACE 

Part 71— Designation of Federal Airways, Controlled 
Airspace, and Reporting Points. 

Part 73— Special Use Airspace. 

Part 75— Establishment of Jet Routes. 

Part 77— Notice of Construction or Alteration Affect- 
ing Navigable Airspace. 


Part 91— General Operating and Flight Rules. 
Part 93— Special Air Traffic Rules and Airport 

Traffic Patterns. 
Part 95-IFR Altitudes. 

Part 97— Standard Instrument Approach Procedures. 
Part 99-Security Control of Air Traffic. 
Part 101— Moored Balloons, Kites, and Unmanned 

Part 103— Transportation of Dangerous Articles and 

Magnetized Materials. 
Part 105— Parachute Jumping. 


Part 11— General Rule-making Procedures. 
Part 13— Enforcement Procedures. 

Subchapter C AIRCRAFT 

Part 21— Aircraft Certification Procedures. 

Part 23— Airworthiness Standards: Normal, Utility, 
and Acrobatic Airplanes. 

Part 25— Airworthiness Standards: Transport Cate- 
gory Airplanes. 

Part 27— Airworthiness Standards: Normal Rotor- 

Part 29— Airworthiness Standards: Transport Rotor- 

Part 33— Airworthiness Standards: Aircraft Engines. 

Part 35— Airworthiness Standards: Propellers. 


Part 141-Pilot Schools. 
Part 143— Ground Instructors. 
Part 145— Repair Stations. 
Part 147— Mechanic Schools. 
Part 149-Parachute Lofts. 

Subchapter I AIRPORTS 

Part 151— Federal Aid to Airports. 

Part 153— Acquisition of U. S. Land for Public Air- 

Part 155— Release of Airport Property from Surplus 
Property Disposal Restrictions. 

Part 157— Notice of Construction, Alteration, or 
Deactivation of Airports. 

Figure 135— Minii 

Sofe Altitudes for AircrofI 

Part 159— National Capital Airports. 

Part 161-Cold Bay, Alaska Airport. 

Part 163— Canton Island Airport. 

Part 165-Wake Island Code. 


ments of age, citizenship, physical condition, knowl- 
edge and experience, and must pass both a written 
and a practical examination on flight techniques. 
These examinations are given by an FAA Safety In- 
spector or by a Flight Examiner. A Flight Examiner 
is an experienced flight instructor appointed by the 
F.'VA to administer flight e.xaminations. 

Requirements vary according to the type of cer- 
tificate the applicant is seeking. Ratings on the 
certificate indicate additional privileges and/or re- 
strictions. A pilot may hold a Student, Private, Com- 
mercial, or Flight Instructor Certificate. Ratings en- 
dorsed on the pilot certificate will indicate the pilot's 
ability to fly under instrument flight rule conditions, 
in single or multi-engine aircraft, helicopters, gliders, 
and land or seaplanes. Airline captains are required to 
have an Air Transport Rating (ATR). Special ratings 
are also required to fly aircraft which exceed 12,500 
pounds gross weight if passengers are to be carried. 


Part 181-Seal. 

Part 183— Representatives of the Administrator. 

Part 185— Testimony of Employees and Production 
of Records in Legal Proceedings. 

Part 187— Fees for Copying and Certifying Federal 
Aviation Agency Records. 

Part 189— Use of Federal Aviation Agency Com- 
munications Systems. 

Specific regulations, by part number, can be ob- 
tained from the Superintendent of Documents, United 
States Government Printing Office, Washington 25, 
D. C. 

Pilot Regulations 

To act as an airplane pilot, an airman must possess 
a pilot certificate issued by the FAA. To obtain a 
certificate, the applicant must meet certain require- 

Air Traffic Rules 

Air traffic rules provide for safety to persons and 
property by regulating the flow of traffic in flight and 
on the ground. In accomplishing this, they establish 
definite patterns and procedures for practically all 
conditions and maneuvers. 

In Part 91 of the Federal Aviation Regulations, the 
air traffic rules are grouped into three sections. The 
first section is called General Flight Rules ( GFR ) and 
consists of those rules which apply to all flights, re- 
gardless of the conditions under which they are con- 
ducted. The following illustrate some of the many 
general rules: (1) Aircraft must not be flown below 
certain specified altitudes (figure 135); (2) Pilots 
must follow definite rules to avoid the possibility of 
collision (figures 136 and 137); and (3) When flying 
within a specified area of an airport served by an 
F.A.A. control tower, pilots must not fly their aircraft 
in excess of certain speeds, must follow specified basic 

Figure 136— Right of Woy for Free Balloons, Gliders, Airships and Airplanes in That Order 






figure H7 — Rights of Way for Aircraft in Flight 

patterns, and must communicate with the tower by 
two-way radio in order to receive specific instructions 
and clearances. 

The second section of Part 91 is called Visual Flight 
Rules (VFR). Pilots fly under VFR when their entire 
flight can be conducted in weather conditions equal 
to or better than the minimums specified in this sec- 
tion. Practically all of the visual flight rules are con- 
cerned with weather minimums which state the 
minimum distance from clouds that aircraft must 
remain, and the minimum horizontal distance that 
a pilot must be able to see. These distances vary 
with the various classes of airspace (Figure 138). 
Additionally, there is a rule that governs the selection 
of altitudes for cross-country flights. 

When weather conditions are below the minimums 
specified for VFR flight, a pilot may not fly unless he 
has both an instrument rating and an airplane which 
is properly equipped for instrument flight. When these 
two requirements are met, a pilot may fly if he ad- 
heres to the rules specified in the third section of 
Part 91, Instrument Flight Rules (IFR). Every detail 
of an IFR flight is very carefully controlled by one 


or more of the FAA Air Route Traffic Control 
(ARTC) centers. To take off, to continue a flight al- 
ready in progress, or to land under IFR conditions, a 
pilot must receive clearance from an Air Route Traf- 
fic Control center. Either in person or by radio, the 
pilot in command must submit and receive approval 
for an IFR flight plan, and he must then follow the ap- 
proved flight plan without deviation. An IFR flight 
plan involves flying at specified altitudes, on a specific 
route, and includes time and position reports over 
designated check points. The ARTC center correlates 
this information from all pilots who are flying within 

F»9VF« 138 — Mmimum Cloud Clearance inside Control Area 


the center's jurisdiction, and continually issues clear- 
ances to keep airplanes separated by assigning dif- 
ferent routes or by time and/or altitude intervals. 
Besides being thoroughly familiar with the vast 
amount of navigational information required to fly 
under instrument procedures, the pilot must also be 
expert in all phases of communication procedures. 
(See Chapter 10.) 


During the early days of aviation, flying activities 
were limited to a comparatively few thousand pilots 
and few hundred airplanes. Since there were no regu- 
lations governing flight activities at that time, there 
were a considerable number of accidents. With the 
expansion of private flying activity, the opening of 
air-mail routes, and the scheduling of commercial pas- 
senger flights, the need for air traffic and safety regu- 
lations became apparent. 

The Air Commerce Act of 1926 established regula- 
tions governing licensing of pilots and airplanes, air- 
ways inspection, air traffic rules and other elements of 
aviation. The Bureau of Air Commerce, operating 
under the U. S. Department of Commerce, was sub- 
sequently replaced by the Civil Aeronautics Adminis- 
tration in 1938, and was, in turn, replaced by the 
Federal Aviation Agency in 1959. The FAA is charged 

with the responsibility of giving flight and ground 
school examinations, operating the civil airways, ren- 
dering assistance to aircraft manufacturers, supplying 
educational institutions with material and guidance, 
and making and enforcing the Federal Aviation Regu- 

The Civil Aeronautics Board, which was created at 
the same time as the Civil Aeronautics Administration, 
still functions as an independent agency. The CAB 
issues certificates of public necessity, regulates the 
economics of air commerce, and is responsible for 
investigation of aircraft accidents. 

Some regulations establish the requirements for 
student, private, and commercial certificates and 
ratings. Other regulations set high standards for the 
aircraft equipment manufacturers, regarding safe de- 
sign, satisfactory materials, and approved construc- 
tion methods. 

Regulations, known as Air Traffic Rules, carefully 
set forth procedures and patterns to insure an orderly 
and safe flow of traffic in the air and on the ground. 
The air traffic rules are arranged in three sections: 
(1) General Flight Rules (GFR) which apply to all 
flights, (2) Visual Flight Rules (VFR) for' flights 
which can be accomplished in weather conditions 
equal to or better than certain specified minimums, 
and (3) Instrument Flight Rules (IFR) for those 
flights which, because of weather, cannot be accom- 
plished under VFR. 


1. Why are government regulations necessary in 

2. What organization governs aviation on an inter- 
national scale? 

3. To what extent do the various states govern avia- 
tion activities? 

4. What is the primary function of the Federal Avia- 
tion Agency? 

5. What is the primary function of the Civil Aero- 
nautics Board? 

6. List four general areas of aviation activity in 
which the FAA is continually engaged. 

7. Where would you send an order for certain 
Federal Aviation Regulations? 

8. What types of requirements must be met so that 
a person may qualify for a pilot certificate? 

9. In which part of the regulations are the Air Traffic 
Rules found? 

10. Name the two conditions of flight for which spe- 
cific traffic rules are written? 

Chapter 12 Space Travel 

Space is man's new frontier. By wide use of the 
airplane, explorers have filled in the few remaining 
blank spaces on the world's map. For new challenges, 
new boundaries, and new explorations, man must look 
either below or above the earth's surface, and he has 
chosen "space" for his next great search. 

Today, with interplanetary travel almost within 
grasp, man stands upon the threshold of an experience 
which has no precedent in his past actions. So it be- 
hooves the airman of today— the spaceman of tomor- 
row—to know the medium in which he will be oper- 

The Solar System 

The earth's solar system, with the sun as its center, 
is a relatively minute section of the vast galactic star 
system called the Milky Way— which in turn is only 
one galactic star system among the many, many sys- 
tems composing the universe. Until man has first 
solved the perplexingly complex problems concerning 
the earth's solar system, he cannot intelligently deter- 
mine the means by which intergalactic travel and 
communication will be accomplished. It is entirely 
possible, however, that when man has discovered the 
secrets of his solar system and developed the methods 
for interplanetary and intergalactic travel and com- 
munication, he will then detect a multitude of planets 
which are comparable to earth and which could sus- 
tain human life. 

To acquire a basis for further study of the solar 
system, there are certain fundamentals which should 
be understood; 

1. The solar system is composed of the sun, nine 
planets and their moons, asteroids, comets, meteor- 
ites, micrometeorites, and dust. 

2. The sun is the center star of the solar system. 

3. All nine planets move around the sun in the 
same direction and in nearly circular paths. 

4. All nine planets orbit around the sun on nearly 
the same plane but at different distances from the sun. 

5. The four inner planets— Mercury, Venus, Earth, 
and Mars— are relatively small dense bodies known as 
"terrestial " planets. 

6. The next four planets in distance from the sun- 
Jupiter, Saturn, Uranus, and Neptune— are called the 
major or giant planets and are principally composed 
of gases with solid ice and rock cores at unknown 
depths below the visible upper surfaces of their at- 

7. Pluto, the most distant planet, is relatively un- 

8. The diameter of the solar system is 79 astronom- 
ical units (a.u.) or 7,300,000,000,000 miles. One astro- 
nomical unit equals 92,900,000 miles, or the mean 
distance of the earth from the sun. (Figure 139.) 

AH around earth's solar system, i.e., the sun and the 
nine planets, lie the numberless other stars of this 
galaxy. A galaxy is a system of stars and can best be 
visualized as a disc standing on edge. (Figure 140.) 
Earth's solar system is located quite far down on the 
disc. Some idea of the tremendous size of earth's 
galaxy is obtained when it is understood that it takes 
four and one-half years for light from the sun to travel 
to its nearest neighbor, the star Proxirna Centauri, and 
26,080 years for sunlight to reach the center of the 
galaxy. These figures are more easily understood when 
it is remembered that it takes only eight minutes for 
the sun's light to reach the earth. In terms of these 
almost unbelievable times and distances, the sun's 
planetary system suddenly seems a smaller, friendlier 
place, and certainly worth closer examination. 

The sun, in astronomical terms, is a "main sequence" 
star with a surface temperature of about -|- 11,000° F. 
Although classified as a medium-small star, it is over 
300,000 times as massive as the earth. All useable forms 
of energy on the earth's surface, with the exception 
of atomic and thermonuclear energy, are directly or 
indirectly due to the storing or conversion of energy 
received from the sun. 

Mercury, the planet closest to the sun, is difficult to 
observe because of its proximity to the sun. Mercury 




Figure 139 — The Solar Syslen 

Planets of the Solar System 






from Sun 

ial Di- 



Gravity at 



Period of 


(miles per 

( miles per 




of year 



second ) 

second ) 

(earth = l) 



88.0 days 

88 days 







224.7 days 








365.25 days 

1 day 







1.88 years 

24 hr. 37 min 







11.86 years 

9 hr. 55 min. 







29.46 years 

10 hr. 14 min. 







84.02 years 

10 hr. 40 min. 







164.79 years 

15 hr. 40 min. 







248.43 years 






has no moon and is about one-twentieth the size of 
the earth. It is a small, rocky sphere which always 
keeps the same side facing the sun. Mercury is not 
known to have any atmosphere. 

Venus cannot be accurately judged since its dense 
and turbulent atmosphere denies a view of its solid 
surface to astronomers. On the basis of available evi- 
dence, it may be presumed that the surface of Venus 
is probably hot, dry, dusty, windy, and dark, beneath 
a continuous dust storm. The atmospheric pressure is 
perhaps several times the normal barometric pressure 
at the surface of the earth. Carbon dioxide is probably 
the major atmospheric gas, with nitrogen and argon 
being present in lesser amounts. 

Mars is slightly more than one-half the size of the 
earth. The atmospheric pressure at the surface has 
been estimated at 8 to 12 per cent of the earth's sea 
level atmospheric pressure, and the atmosphere is be- 
lieved to consist largely of nitrogen. Topographically, 
its surface is quite flat, with no abrupt changes in 
elevation and no prominent mountains. The climate 
would be similar to that of an eleven-mile high desert 

on earth, i.e., noon summer temperatures reaching a 
maximum of -|-80° to +90°, but falling rapidly during 
the night to reach a minimum of — 100° F. Bleak and 
desertlike as Mars appears to be, with no free oxygen 
and little, if any, water, there is some evidence that 
indigenous life forms may exist. 

Jupiter, Saturn, Uranus, and Neptune have so many 
characteristics in common that they may be treated 
together. They are all massive bodies of low density 
and high diameter. They all rotate rapidly and have a 
small dense rocky core surrounded by a thick shell of 
ice and are covered by thousands of miles of com- 
pressed hydrogen and helium gases. Temperatures at 
the visible upp>er atmospheric surfaces range from 
—200° F. to —300° F. Many of their moons are larger 
than the earth's moon. Although reliable physical data 
on these moons are lacking, it is possible that they may 
be more acceptable for space flight missions than the 
planets about which they orbit. 

Pluto is the most distant planet of the solar system 
(3,675 million miles from the sun). Almost nothing is 
known about this most extreme member except its 


orbital characteristics, the fact that it is extremely 
cold, (light from the sun takes five and one-quarter 
hours to reach Pluto), and that it has a diameter less 
than one-half that of earth. 

Asteroids are a group of substantial bodies more or 
less concentrated in the region between the orbits of 
Mars and Jupiter. It is possible that these chunks of 
material may be shattered remains of one or more 
planets. Quite a few of the asteroids are as much as 
100 miles across, with the largest, Ceres, being nearly 
500 miles in mean diameter. 

Comets are very loose collections of orbital material 
that sweep into the inner regions of the solar system 
from the space beyond the orbit of Pluto. Some return 
periodically, e.g., Halley's Comet, and some never do. 
Their bodies consist of rarified gases and dust, and 
their heads are thought to be frozen gases or ices. 

Meteorites enter the earth's atmosphere in the form 
of meteoritic particles, at velocities of 7 to 50 miles per 
second. Most of these particles are decomposed in the 
upper atmospheres but a few do reach the earth's 
surface. The range of meteoritic material entering the 
earth's atmosphere is from 25 tons to 1 million tons 
per day. The information concerning meteoritic input 
is very uncertain, as the estimated tonnage range sug- 
gests. The meteoritic content of other space regions 
is unknown. 

Figure 140 — This beautiful view of one of the ditc-shaped galaxiei in 
the southern hemisphere of the sky is similar to our own galaxy, the 
Milky Way system. 

Micro-meteorites and dust originate as cometary 
refuse and are situated along the orbits of the comets 
with the highest concentration being in the ecliptic— 
the plane of the earth's orbit. 


Before spaceman can come to grips with the phys- 
ical requirements involved in space flight, he must 
first free himself from the barriers presently imposed 
by the earth's atmosphere. For a better understanding 
of the atmosphere, astronomers have divided it into 
sections. These are: 

1. Troposphere— This air region extends from the 
earth's surface up about ten miles and encompasses 
the extreme altitude range of today's conventional air- 
craft. Only about 20 per cent of the troposphere is 
oxygen; the remainder is largely nitrogen. 

2. Stratosphere— This air region extends from ten 
miles up to about sixteen miles up. In this area a 
reciprocating engine's power output is reduced to 
zero, since absolute pressure falls below 212 pounds 
per square foot. Temperatures average about —70° F. 
and due to the lack of air pressure at twelve miles and 
above, the airman's blood would boil unless he is 

3. Mesosphere— This air region extends from six- 
teen miles up to about fifty miles up. This is a rather 
unusual area because the temperature averages about 
50 degrees above zero in comparison to the — 70° F. 
in the next lower level and — 104° F. in the next upper 
level. There is also a large concentration of ozone in 
this region, which absorbs much of the sun's ultra- 
violet rays, thereby shielding the earth from cosmic 
ray bombardment. 

4. Thermosphere— This air region extends from fifty 
miles up to around 200-300 miles up. Here again the 
temperature is unusual in that it varies from —104° F. 
at its lowest boundary to +2200° F. at its upper limits. 
The thermosphere is also called the ionosphere be- 
cause of its intense electrical activity. Atoms and mole- 
cules in this layer are bombarded by powerful electro- 
magnetic waves from the sun and become electrified 
or ionized. The ionosphere has a strong influence on 
all radio transmission on the earth. 

5. Exosphere— This air region extends from 200-300 
miles up to about 1,000 miles up and begins to blend 
into outer space. 

The three following classifications have been estab- 
lished only for purposes of clarifying scientific space 

6. Terrestrial Space extends from 1,000 miles up to 
10,000 miles up. 

7. Cislunar Space extends from 10,000 miles up to 
100,000 miles up. 


8. Translunar Space extends from 100,000 miles up 
to 1,000,000,000 miles up. 

Beyond the above designated categories of space, 
scientists have arbitrarily named the regions, in 
ascending order, (9) interplanetary space, (10) inter- 
stellar space, and (11) intergalactic space, without 
having specifically determined the lower and upper 

To conquer these giant distances in space and time 
from the earth to the edges of its solar system and 
beyond to the stars, man must develop new theories 
of propulsion, guidance, and physical existence. Just 
as aeronautics is the science of air travel, so astro- 
nautics is the science of space travel. Man has now 
discovered that neither the piston engine nor the jet 
engine used in air travel will be of assistance in his 
efforts to break the atmospheric barrier. For space 
travel, man has returned to an ancient propulsive de- 
vice—the rocket. 

The History of Rockets 

The earliest authentic records show that in 1232 
A.D. the Chinese used rockets— arrows of flying fire— 
against the Mongols during the siege of Kaifung-fu. 
The first mention of rockets being used in Europe 
appears in the Chronicle of Cologne in 1258 and again 
in 1379 when an Italian historian credited the rocket 
as being the decisive factor in the battle for the Isle of 

There is an account, which was published in the 
late 18th century, which refers to the large number of 
rockets fired during a battle at Paniput, India. Records 
of the British campaign in India, particularly at the 
Battle of Mysore, relate the experiences with Indian 
rocket troops. The rockets were used primarily against 
the British cavalry and were cased in iron, 8 inches 
long by 1/2 inches in diameter, with a spiked nose. 
They were balanced by a stick of bamboo or iron 
approximately 8 feet long and were launched by spe- 
cially trained "rocketeer" troops. Rocket warfare was 
quite effective against the British forces until they, 
themselves, developed their own projectiles. 

Up to this period the rocket's primary use had been 
as a weapon. In 1826, however, it was put to use as 
a life-saving device. Four rocket life-line stations were 
established on the Isle of Wight in the English 
Channel. Since that time, life-line rockets have been 
put into world-wide use and have helped to save over 
15,000 lives around the coast of Great Britain alone. 
Continued experimentation and development of rocket 
capabilities proceeded during the latter part of the 
19th century, with William Hale, an American, devel- 
oping a rocket which rotated by offset exhaust nozzles, 

thereby establishing greater flight stability. 

The first practical studies concerning rocket propul- 
sion as a means of attaining space travel capability 
originated near the end of the 19th century and are 
generally credited to three men: Konstantin Ziolkow- 
sky, a Russian mathematics teacher; Herman Gans- 
windt, a German law student; and Robert Esnault- 
Pelterie of France. 

The first significant American contribution to rockets 
was made by Dr. Robert H. Goddard (1882-1945), a 
Clark University physicist. When Dr. Goddard started 
his experiments with rockets, little related technical 
information was available. Through his scientific 
studies he pointed the way to the development of 
rockets as they are known today. He discovered that 
a shaped, smooth, tapered nozzle would drive the 
rocket eight times faster and 64 times farther on the 
same amount of fuel. Dr. Goddard also found that the 
solid fuels of that time would not give the high power 
or the duration of power needed for a rocket capable 
of extreme altitudes. On March 16, 1926, after many 
trials, he successfully fired the first liquid fuel rocket, 
which attained an altitude of 184 feet and a speed of 
60 mph. Later Dr. Goddard was the first to fire a 
rocket that reached a speed faster than the speed of 

Dr. Goddard was the first to develop a gyroscopic 
steering device for rockets and was the first to use 
vanes in the jet stream for stabilization. After proving 
on paper and in actual test that a rocket can operate 
in a vacuum, he developed the mathematical theory 
of rocket propulsion and rocket flight, including basic 
designs for long-range rockets. He was also the first 
to patent the idea of step rockets. A step rocket is one 
that is carried by another rocket, with the second ig- 
niting when the first has consumed its fuel load. 

Professor Herman Oberth, a German, was conduct- 
ing rocket research in the early 1920's. In 1923, he 
published a book, "The Rocket into Interplanetary 
Space," which pointed the direction for others to fol- 
low. In 1925, Dr. Walter Hohmann wrote a book 
called "The Attainability of the Celestial Bodies," 
which dealt with the conservation of energy in de- 
parture trajectories from the earth, return to earth, 
circular orbits to other planets, and landing on celes- 
tial bodies. These technical books were quickly fol- 
lowed by ones which were written for the general 

The researches and writings of Oberth, Hohmann, 
Valier, and Ley established the foundation for German 
experiments. The first European liquid-fuel rocket was 
successfully tested in 1931. The following year Walter 
Domberger secured approval from the German gov- 
ernment to develop further liquid-fuel weapons, and 


in 1936, when the "Peenemunde Project" was organ- 
ized, General Dornberger became the commander of 
this experimental missile test station. The majority of 
his research staff were former members of the German 
Rocket Society. 

In the post World War 11 era, both the United 
States and Russia profited from the research accom- 
plished by the Germans at Peenemunde and at other 
rocket research centers. Russia apparently concen- 
trated from the start on long-range ballistic missiles, 
while the United States concentrated its efforts on 
rocket-powered air defense weapons. Today, there are 
many missile projects in various stages of progress, 
both offensive and defensive weapons, with rocket, 
turbojet, and ramjet engines. During this post World 
War 11 era, the United States was aided in rocket re- 
search by the many German scientists who came to 
this country and who later became naturalized 

The guided missile emerged through an evolutionary 
rather than a revolutionary process. The development 
cycle of rockets and missiles has accelerated rapidly 
during the last 30 years. This increased activity is due 
in large part to the wealth of information on aero- 
dynamics, propulsion, and guidance which has been 
obtained through the development of the airplane. 

Current Space Problems 

Rocket engines are often confused with jet engines. 
Both rockets and jets operate on the principle of 
action and reaction, both burn a fuel-oxygen mixture, 
and both exhaust the burning gases created by the 
fuel mixture. There is, however, one important differ- 
ence. A jet engine gets the oxygen it needs for com- 
bustion from the outside atmosphere whereas a rocket 
carries its oun oxygen. A jet, therefore, can operate 
only within the earth's atmosphere but a rocket can 
operate anywhere. 

There is also a source of confusion in the difference 
between a missile and a rocket. Basically, a missile is 
an object thrown at a target, i.e., a weapon. In modern 
military language a missile is a powered vehicle de- 
signed to carry explosives to a target. There are at 
present two types of missiles: (1) the guided missile, 
which is capable of a change of direction by internal 
or external command at any time during its flight; and 
(2) the ballistic missile, which is powered and guided 
during the first part of its flight only, after which it 
proceeds like a thrown rock, without power or guid- 

Rocket refers only to the type of propulsion, i.e., 
an engine. Many missiles are rocket-powered and 
there is a tendency to call them all rockets, but a 

rocket can perform many other jobs— principally the 
propulsion of vehicles into space. 

The projected probing of space is man's greatest 
challenge today. Research rockets have been success- 
fully fired into space and much valuable information 
has thereby been acquired. The technological de- 
mands for a manned vehicle capable of making a 
space flight are many: 

1. A propulsion system to sustain the initial speed 
for a long period must be developed. 

2. A guidance system of incredible accuracy must 
be created. 

3. An airframe far sturdier than any ever built, to 
protect the crew from the disastrous effects of hull 
puncture by space matter, must be designed. 

4. A complete, built-in, earth-like environment for 
the crew must be devised. 

5. A retrieving or re-entry into the earth's atmos- 
phere must be conceived. 

These are the major problems which industry and 
government, in a joint effort, are attempting to solve. 


Propulsion systems, i.e., rocket engines, are distin- 
guished by the type of mechanism and propellant used 
to produce thrust. The most common type of rocket 
engine employs chemicals to produce, by chemical 
combustion, the hot exhaust gases required to propel 
the vehicle. The chemicals are of two types, fuel and 
oxidizer— similar to gasoline and oxygen in an auto- 
mobile engine. Both are required for combustion, and 
both may be in either a solid or liquid form. 

Solid chemical rocket engines combine the fuel and 
oxidizer into a solid mass called a grain. The propel- 
lant grain can be moulded into any desired shape, but 
it usually is cast with a hole down the center. This 
hole, called a perforation, may be shaped in many 
unique ways— a circle, a star, a gear. Its perforation 
shape and size affects the burning rate, or number of 
pounds of gas generated per second, and, thereby, 
affects the thrust of the engine. 

The propellant grain, after being properly moulded 
with the desired perforation shape, is inserted into 
a metal or plastic case. When the entire missile has 
been assembled and is ready for flight, the propellant 
grain is ignited by a pyrotechnic device usually trig- 
gered by an electrical impulse. The propellant grain 
bums on the entire inside surface of the perforation, 
causing the hot combustion gases to pass down the 
grain and be ejected through the nozzle, thereby pro- 
ducing the needed thrust. (Figure 141.) 

Liquid chemical rocket engines are bipropellant 
in that two separate propellants, a liquid fuel and a 
liquid oxidizer, are used. Each propellant is contained 


in a separate tank and is mixed with the other only 
upon injection into the combustion chamber. The two 
chemical propellants are fed into the combustion 
chamber either by pumps or by pressure inside the 

Typical fuels now used in the liquid chemical en- 
gine include kerosene, alcohol, hydrozine, and hydro- 
gen. O.xidizers include nitric acid, nitrogen tetroxide, 
oxygen, and fluorine. Two of the best oxidizers are 
the liquefied gases, oxygen and fluorine, but these 
gases exist as liquids only at very low temperatures. 
This low temperature factor adds to the difficulty of 
their use in rockets. In general, the liquid propellants 
in common use today provide greater thrust capabili- 
ties than do presently available solid propellants. On 
the other hand, liquid fuels require more complex 
engine systems. (Figure 141.) 

Nuclear rocket engines, as a source of missile pro- 
pulsion, have not yet achieved operational capability. 
Present research indicates that the nuclear rocket will 
not utilize the combustion process which is typical 
of the solid and liquid fuel engines. Instead, the hot 
exhaust gases necessary to provide needed thrust will 
be developed by passing a liquid through a fission 
reactor. Liquid hydrogen is the propellant most often 
considered for a nuclear rocket because it yields the 
lightest possible exhaust gas. The liquid hydrogen 
would be stored in a single tank, forced into the reac- 
tor by a pump, heated and expanded by the reactor, 
then exhausted through a conventional rocket nozzle 
to obtain thrust. 


^(MiusiiM (umn 


Figure 141 — Schematic Diagram of Liquid and Solid Fuel Rocket Engines 

Several other types of rocket engines have been 
proposed but exceedingly complex problems are still 
to be solved before they may be advantageously used. 
There is the plasma rocket, which would utilize elec- 
tricity to heat the propellant directly by discharging 
a powerful arc through it. The restricting factor is 
that such a large amount of electrical power, about 
150 kilowatts, is required to produce one pound of 

A photon rocket would require light or some other 
radiation to be generated and then exhausted from 
the rocket in a focused beam. Such a system, how- 
ever, would use energy very inefficiently unless matter 
could be completely converted into energy. A large 
searchlight, for example, is in a sense a photon rocket, 
but it yields less than one ten-thousandth of a pound 
of thrust for an electrical power consumption of 100 

An ion rocket would be propejled by causing each 
molecule of the propellant— usually conceived as being 
an alkali metal, probably cesium— to have an electrical 
charge, i.e., the propellant would be ionized. It would, 
theoretically, then be possible to accelerate the 
charged molecules, or ions, to very high velocities 
through a nozzle. However, the amount of electric 
power re(|uired to charge and accelerate the molecules 
is very high. For example, an ion rocket using cesium 
for the propellant would require about 2100 kilo- 
watts of electric power to produce one pound of 

There are two general measures of performance of 
a rocket engine: (1) the amount of thrust, which 
determines the amount of propellant that must be 
used to accomplish a given task, and (2) the fixed 
weight of the engine including the necessary tankage, 
power supply, and structure. At present, the chemical 
rocket engine, although a fairly lightweight device, 
cannot provide sufficient thrust to sustain flight for a 
long period. The principal obstruction to general use 
of a plasma, photon, or ion rocket engine is the lack 
of a lightweight electrical power system. The nuclear 
rocket engine, however, ofi^ers the greatest potential 
for space flight if temperature limitations on the walls 
of the missile airframe can be solved. 


Many factors govern the choice of a specific guid- 
ance system for a guided missile, but the primary con- 
sideration is the range or distance which the missile 
must fly. In addition, the prescribed purpose of a 
missile may dictate that the missile be guided during 
any one or all of its flight phases, i.e., launching, mid- 
phase, and initial flight. The ballistic missiles are 
commonly guided only during their launching phase 


and initial flight, while a cruise-type missile uses mid- 
course guidance continually throughout its flight. Air- 
to-air missiles employ terminal guidance systems that 
lead the missile directly to the target. 

Space flight missions in the near future will use 
ballistic rockets— those which are powered and guided 
only during the first part of their flight— and the guid- 
ance of such vehicles will be improved versions of 
current ballistic missile guidance techniques. 

The major types of guidance systems now in use 
are (1) pre-set, (2) command, (3) target seeking, 
(4) inertial, and (5) celestial navigation. Each of 
the above-listed guidance systems must be able to 
measure the missile's position and velocity, compute 
the control actions which are needed to readjust the 
missile's position and velocity, and then deliver the 
necessary commands to the vehicle's control system 
so that the needed corrections can be made. 

When pre-set guidance is used, a predetermined 
flight course is set into the missile's internal control 
system before the missile is launched. This preplanned 
flight course will have considered the predicted 
atmospheric conditions, the probable location of the 
target, and the performance capability of the missile. 
After the missile is launched, it will obey the pre-set 
control system's commands, going through all the 
motions which have been set into the mechanism. This 
guidance system is simple, reliable, inexpensive, and 
not vulnerable to countermeasures; however, once it 
has been fired, the launching crew no longer has con- 
trol over it. Moreover, this guidance system is not 
considered to be highly accurate. 

In the command guidance system the missile can 
be controlled throughout its entire flight path. Control 
of the missile's actions is achieved by using radio 
beams or some other electronic device which can 
send back information regarding the missile's posi- 
tion, direction, and speed to a computer on the ground. 
The computer swiftly compares the missile's present 
position with its desired position and then orders 
the necessary corrections made by sending radio im- 
pulses back to the weap>on's control system. 

There are several variations of the command guid- 
ance system currently being tested. One is the Wire 
Rider, in which a wire connects the missile control 
system and the command station. As the weapon flies 
toward its target, the wire unreels. Electrical impulses 
can then be sent through the wire to the control sys- 
tem to guide the weapon to the target. This type of 
guidance system is used for very short-range efforts 
such as anti-tank warfare. 

A second type of command guidance is the Beam 
Rider, in. which a radar beam remains fixed on the 
target and the missile rides the beam to its intended 

destination. An air-to-air missile, using the Beam Rider 
technique, is also provided with sensing instruments 
which determine the missile's position relative to the 
beam and make the needed adjustments. When a 
ground-to-air missile is launched, two beams are used. 
One beam tracks the target and the other beam tracks 
the missile. A ground computing system determines 
the error between the two beams and then corrects 
the missile's course until the two beams coincide at 
the target. 

A third method of command guidance is to have 
in the nose of the missile a television camera and 
transmitter which send back to a ground operator a 
picture of what the missile is "seeing." The operator 
controls the flight of the missile and when the objec- 
tive is sighted, he steers the missile into the target. 
The primary advantage of this system is that the 
remote-control operator can be hundreds of miles 
away from the missile and the target. 

A missile using target-seeking or homing guidance 
is often referred to as "the most intelligent" of all 
missiles because it actually perceives the target and 
then computes its own control signals to guide itself 
to the target. If the missile is to "see " the target, the 
target must have some distinctive source of heat, light, 
magnetism, or radio impulse which the missile can 
accurately detect. Missiles which employ this method 
to find and destroy a target are called passive seekers. 
An active seeker is a missile which "illuminates" the 
target by radar signals and then guides itself toward 
the target by following the reflected signal. 

Inertial guidance is fundamentally a pre-set guid- 
ance system with a course-and-distance measuring 
mechanism added. Basically, an inertial guidance sys- 
tem is composed of three accelerometers and a com- 
puter. An accelerometer is a small mechanical device 
which sensitively responds to any acceleration change 
of the missile. Each accelerometer measures accelera- 
tion in a single direction and can operate only during 
powered flight. The "weightlessness" of space com- 
pletely nullifies the accelerometer's operation. The 
information acquired by the accelerometers during the 
period when they are measuring the sideways and 
the forward and backward movements of the missile 
is relayed to the missile's internal computer, which 
constantly measures velocity, distance traveled, and 
course. The computer compares the information con- 
cerning its present position, which it received from 
the accelerometers, with the position it "knows" it 
should maintain, and then makes corrections and 
necessary adjustments through the missile's autopilot. 

Celestial navigation guidance is accomplished by an 
automatic sextant which takes continual sights on pre- 
selected stars— much in the same manner as does an 

airplane or ship navigator. The missile's automatic 
equipment measures the angle bet\veen the course 
of the missile and the course to the star. This infor- 
mation is relayed to the missile's computer system, 
which evaluates the report, prepares needed correc- 
tions in the missile's position, and then dispatches 
the new or revised knowledge to the missile's control 
system. When this guidance system is used alone, it 
is known as "Automatic Celestial Navigation (ACN)," 
but it is most often used in conjunction with and to 
double check the inertial guidance system. When 
celestial navigation is used in this manner, it is known 
as the "Stellar Supervised Inertial Auto-navigator 


Today's military intercontinental and intermediate- 
range ballistic missiles will be used as man's spring- 
board into space. In fact, putting a satellite into orbit 
—once the necessary propulsion and guidance systems 
have been produced— is much simpler than putting 
a warhead on a target halfway around the world. 

An orbit is a path in which a body moves in relation 
to its source of gravity. There are four types of orbits, 
all named after the conic sections, i.e., the four basic 
curves derived by intersecting a cone with a plane. 
(Figure 142.) 

1. Circle. A body traveling around the earth at a 
constant speed and on a path which at all times is 
equidistant from the earth's center of gravity follows 
a circular orbit. 

2. Ellipse. A body traveling a closed path which is 
longer than it is wide follows an elliptical orbit. 

3. Parabola. A body traveling at such a high 
velocity that it no longer follows a closed path but 
escapes into space follows a parabolic orbit. 

4. Hyperbola. A body traveling in essentially a 
parabolic orbit, but which has the ability to change 
its position with respect to the sun, follows a hyper- 
bolic orbit. (Figure 142.) 

Basically, a satellite is put into orbit by accelerating 
it to somewhere above 18,000 mph but less than 25,000 
mph. This range of speed is known as orbital velocity, 
i.e., the satellite is projected far enough out and at 
a fast enough speed so that the earth's gravity does 
not pull it back, yet its velocity is not so great that 
it is released from the earth's gravity and flies on into 
space. Thus, satellites remain in orbit for the same 
reason that the moon and planets remain aloft. There 
is a state of balance between the earth's gravity and 
the satellite's centrifugal force. This state of balance 
is achieved, however, only when the orbiting satellite 
follows a nearly circular path. 

At the present time the orbits of most artificial sat- 


C D 


(Parallel to 
line XY) 

Figure 142 — Conic Sections and Basic Orbits 

ellites are elliptical, i.e., egg-shaped; conse(juently 
the "balance of power " is constantly shifting from the 
earth's gravitational pull to the satellite's centrifugal 
force, with a consecjuent change in the speed of the 

There are two key points in the elliptical flight path 
of the satellite— the apogee and the ))erigcc. (Fig- 
ure 143. ) The perigee is that point of the satellite's 



Figure 143 — The Satellite Ellipse 


orbit which is closest to the earth's surface; the apogee 
is that point of the sateUite's elhptical flight path 
which is farthest from the earth's surface. 

As the satclHte flies toward apogee, it gradually 
loses its initial velocity because it is traveling away 
from earth and against earth's gravitational pull. 
When it reaches apogee, earth's gravitation overcomes 
the satellite's centrifugal force— velocity— and gravi- 
tation then draws the satellite back toward the earth's 

Throughout the next half revolution of the satellite 
around the earth, the satellite drops through a long 
arc, picking up the velocity it lost on its outward 
swing. At perigee the satellite is moving at maximum 
speed— the centrifugal force exceeds gravitational pull 
—and starts shooting ofi^ into space again. This process 
is repeated over and over again and if the elliptical 
flight path does not reenter the earth's atmosphere, 
the satellite will remain in orbit indefinitely. 

Satellites are usually launched in an easterly direc- 
tion in order to take advantage of the earth's west-to- 
east rotation. Maximum impetus for satellite launch- 
ings would be acquired if the missiles were launched 
from bases along the equator, where the surface 
rotational velocity is 1,000 mph, e.g., a rocket fired 
due east from the ecjuator would have a 1,000 mph 
bonus toward its orbital or escape velocity. 

There are two basic methods for achieving a lunar 
or interplanetary flight: (1) a launching from the 
earth's surface, and (2) a launching from an orbiting 
space station. While there would be little difference 
in the techniques used, there would be a major dif- 
ference in the powerplant requirements, since a lunar 
or interplanetary trip starting from a satellite needs 
much less power. 

In calculating a flight path to the moon, an astro- 
nautical engineer must estimate the following effects: 

1. The gravitational fields of the earth, sun, and 

2. The earth's atmosphere. 

3. The earth's rotation on its axis. 

4. The moon's orbit around the earth. 

5. The inclination of the earth's axis to the ecliptic 
—the plane of the earth's orbit. 

6. The inclination of the moon's orbit to the eclip- 

7. The performance capability of the space vehicle. 

The moon will not be an easy target since its diameter 
is about one-fourth that of the earth; its orbital 
velocity is 2,268 mph, and its distance from earth 
alternates between 221,463 miles at perigee to 252,710 
miles at apogee. 


In theoiy, recoverable satellites and spacecraft will 
begin their reentry into the earth's atmosphere at a 
tangent to the earth's surface. The upper atmosphere 
will be used as a drag brake to decelerate the vehicle's 
speed gradually from the approximately 19,000 mph 
initial entry speed. As the returning spacecraft pro- 
gresses toward the earth's surface, its flight path will 
steepen and the decelerating vehicle will lose altitude 
more quickly. In contrast, the ballistic missile will 
begin entry at quite a steep angle, with an initial 
speed of about 15,000 mph. 

This high-speed reentry point has caused another 
major roadblock to space travel. All types of entry 
vehicles will exchange their kinetic energy for heat 
energy during the entry process. The ballistic missile 
will make this transformation to heat energy in a 
very brief period, while the more carefully planned 
flight paths of satellites and other spacecraft extend 
the heating process over a longer period. In all cases, 
however, this aerodynamic heating caused by the 
enormous entry speed presents staggering engineer- 
ing problems, with destruction of the vehicle being 
the penalty for unsatisfactory solutions. 

At present there are several known methods for 
dealing with the intense heat of high-speed atmos- 
pheric entry. Recently a practical aerodynamic method 
for dumping a large fraction of the heat generated 
during reentry was developed by employing blunt 
nose cones. 

A second method to keep the vehicle's skin tem- 
perature within tolerable limits is to use aerodynamic 
lift to keep the vehicle at higher altitudes for a longer 
period before slowly permitting it to enter denser 
portions of the earth's atmosphere. 

Several fluid cooling systems have been designed, 
one of which pumps a cooling fluid through passages 
next to the vehicle's skin to absorb and carry away 
incoming heat. 

Another method now being studied by the National 
Aeronautics and Space Administration (NASA) is 
called ablation cooling. The surface of the space vehi- 
cle would be coated with a substance which pro- 
gressively vaporizes during heating. The vaporizing 
process would not only absorb heat but would also 
generate gases which would insulate the skin from 
heat penetration. 

Radiation also provides cooling attributes during 
an entry flight. A moderate increase in a vehicle's 
surface temperatures in comparison to the cold, sur- 
rounding atmosphere will permit a sizeable increase 
in the quantity of heat which radiates away from the 
missile's skin. If the metal surface of the missile can 

withstand the exceedingly high temperatures which 
are created by air friction, radiation will supply all 
the cooling that is needed. Unfortunately the problem 
is intensified because the hot surface of the vehicle 
radiates in toward the cabin as well as out into the 

Stability in flight is another major area still to be 
solved if reentry of spacecraft into the earth's atmos- 
phere is to succeed. Research is presently being car- 
ried out to determine what kinds of stability are 
required by space vehicles and how much stability 
must be provided to make a given spacecraft design 
easily controlled. Without stability there can be no 
satisfactory, safe, successful return to the earth by 
satellites, ballistic missiles, or spacecraft. 


There are numerous physical problems to be solved 
before a manned missile can be launched into space. 
Those which are requiring the most attention from 
astronautical scientists at the present time are ( 1 ) ac- 
celeration, ( 2 ) weightlessness, and ( 3 ) physical needs. 

Acceleration. To achieve escape velocity from the 
earth's atmosphere, a manned missile must acquire a 
speed in excess of 25,000 mph. This speed indicates 
that a tremendous amount of acceleration must be 
developed during the launching phase and for a short 
period during initial flight. As the missile's upward 
speed increases, the fuel tanks are rapidly drained, 
causing the mass of the missile to decrease, and as 
the mass decreases, the acceleration is increased even 

Passengers in the missile will feel the direct impact 
of the astounding forces which move them upward. 
The inertia of their bodies will oppose the continuous, 
drastic change in speed and, as a result, they will be 
pressed against the bottom of their bunks by a sheer 
irresistible force. These tremendous "g-forces"— forces 
of gravity exerted on a body by the mass of the earth 
—will cause serious difficulties in blood circulation and 
in breathing. 

Flight surgeons and other scientists have devoted 
a great deal of research effort to find solutions or 
remedial activities to nullify the greatly increased 
body weight during acceleration. The rigors of pow- 
ered ascent which future spacemen must withstand 
touch the tolerance limits of the human organism; 
but by the careful selection and training of healthy 
and physically fit individuals, scientists are fairly cer- 
tain a human body will be able to withstand this 
initial acceleration phase of space flight. 

Weightlessness. Of all the phenomena that will be 


associated with space flight, weightlessness will be 
the strangest. The state of weightlessness is caused by 
an intricate interplay of the physical forces to which 
the ship and the men are subjected during their flight 
through space. The passengers will sustain the feeling 
of weightlessness as long as the rocket engines are 
out of operation. Weightlessness cannot be avoided 
since the theoretical mechanics of space flight entail 
travel by coasting. However, space technicians are 
presently searching for a method to impart rotating 
capabilities to the missile, i.e., revolving the vehicle 
at the same time that it travels forward. This rotation 
effect would tend to decrease the weightless condition. 

Physical Needs. The scientific skills and experience 
which have been used in the past to create useful 
and livable physical conditions by artificial means 
will be urgently needed in order to equip man for 
his survival in space. Using only the spaceship and 
the satellite, astronautic technicians must create an 
artificial, though minute, earth. Primary consideration 
will be given to solving the vital breathing and food 
consumption problems. 

Unlike a submarine, where the shell is built to keep 
water out, a spaceship must be designed to keep the 
air in. In addition, although the human organism 
does not require an excessive amount of oxygen, it 
does require some— about an ounce an hour- all the 
time. The net weight of the oxygen is small, about 
three pounds per day per man, but the weight of 
the storage containers is large. Therefore, space sci- 
entists are presently attempting to devise a method of 
reclaiming the oxygen which is exhaled during the 
breathing process. In conjunction with the problem of 
lack of oxygen, engineers must develop an air- 
conditioning system which will remove from the cabin 
air all substances released by man and his equipment 
which are potentially hazardous. 

On extended trips through space, it would be desir- 
able for the morale and health of the crew to provide 
food that is both varied and of high quality. Dieticians 
and food technologists are presently concerned with 
three new methods for food preservation: (1) Gamma 
irradiation, (2) Beta irradiation, and (3) freeze- 
drying. In the first two methods, gamma rays or elec- 
trons are used to extend the storage life of foods by 
stopping the sprouting process and by destroying 
microorganisms, parasites, and insects. In the case 
of freeze-drying, food is first frozen, then placed in a 
vacuum and subjected to an electromagnetic beam 
which causes the ice crystals to turn quickly into a 
gaseous state. The resulting product will have lost 
90 per cent of its weight, and the bacterial and en- 
zyme activities of the food will have been suspended. 


Figure 144 The USAF Titan ICBM is launched from Cape Conaveral, Florida, on another successful 5,000 mile flight. OfTiciol USAF photo. 



Since earth has been well explored, man has now 
turned his attention and efforts toward a new frontier 
—space. Through scientific research, man knows that 
the earth is only one of nine planets, plus a central 
star, the sun, which composes his solar system. He has 
learned that his solar system is but a small portion 
of a galactic star system, which, in turn, is but one 
galactic star system among the many that compose 
the universe. 

Historically, rockets were first described and used 
by the Chinese in the 13th century. Rockets were in- 
termittently employed during the next six centuries, 
generally as weapons or for pyrotechnic display. Near 
the end of the 19th century, the Russian, Ziolkowsky, 
the German, Ganswindt, and the Frenchman, Esnault- 
Pelterie, suggested that rockets could be developed 
as a method to propel man into space. In the early 
1900's, Dr. Robert H. Goddard and Professor Herman 
Oberth contributed extensively to rocketry's scientific 
knowledge. The German government quickly realized 
the potential in rocket propulsion and established the 
"Peenemunde Project" in 1936 to permit further ex- 
perimentation and research on missile design and 

Currently, space scientists are confronted with 
many complex problems which must be solved before 
manned space flight can become a reality. In the 
area of propulsion, engineering research and testing 
techniques have developed solid-fuel and liquid-fuel 
propellants to a fairly high degree of useability. In 
addition, astronautic engineers are attempting to 
develop practical nuclear, plasma, photon, and ion 
rocket engines which would increase the thrust and 
acceleration characteristics of the missile. 

1. Name the planets which revolve around the 

2. Who were the first tliree men to complete prac- 
tical studies concerning the use of rocket pro- 
pulsion as a means of space travel? 

3. Name three of the many discoveries which are 
generally credited to Dr. Robert H. Goddard. 

4. Why are rocket engines often confused with jet 
engines? How do they differ? 

5. Discuss briefly the propulsion system of a nuclear 
rocket, a liquid chemical rocket, a photon rocket, 
and a solid chemical rocket. 

6. What is meant by pre-set guidance, a beam rider, 
and an active seeker? 

7. What is an astronomical unit, a galaxy, and an 

A missile's guidance system must be highly accu- 
rate while completing an exceptionally complicated 
task. The commonly used types of guidance systems 
in today's missiles are (1) pre-set, (2) command, 
(3) target seeking, (4) inertial, and (5) celestial 
navigation. The particular guidance system which is 
incorporated into a missile depends upon the missile's 
target, range, and speed. 

There are four types of orbits, or flight paths, which 
a missile or satellite will follow during its travel 
through space: (1) circular; (2) elliptical; (3) para- 
bolic; and (4) hyjoerbolic. To be put into a circular 
or elliptical orbit, the spacecraft must be accelerated 
to at least 18,000 mph but not more than 25,000 mph. 
Speeds in excess of 25,000 mph will free the space- 
craft from the restrictions of the earth's atmosphere 
and cause it to fly out into space. Satellites are usu- 
ally launched in an easterly direction to take advan- 
tage of the added impetus provided by the earth's 
west-to-east rotational velocity. 

Reentry into the earth's atmosphere is still a diffi- 
cult problem which must be solved prior to a manned 
space flight. Various cooling systems are now being 
studied to alleviate the exceedingly high temperatures 
which will build up on the surface of the spacecraft 
during its reentry phase. Closely allied to the high 
temperature problem are the requirements of control 

Among the many human physical problems now 
being tested, (1) acceleration, (2) weightlessness, 
and (3) physical needs concerning food and oxygen 
are of major importance. Each of these three activi- 
ties require special attention by space scientists since 
an artificial earth must be re-created within a missile 
or satellite if man is to exist for the long periods 
required by interplanetary and intergalactic space 

8. What is inertial guidance? 

9. What is weightlessness and why is it important 
to space flight? 

10. What are the two general measures of perform- 
ance of a rocket engine? 

11. What is a guided missile? A ballistic missile? 

12. Why are satellites launched in an easterly direc- 

13. What human problems occur during the initial 
acceleration of a manned space vehicle? 

14. Define (1) apogee, (2) perigee, (3) orbital ve- 
locity, (4) troposphere, and (5) comet. 

15. How will ablation cooling assist a spacecraft to 
reenter the earth's atmosphere? 

16. What is the difiFerence between a missile and a 

Chapter 13 Space Exploration 

Beginning with the successful launching of Explorer 
I in January 1958, the United States has embarked on 
a thrilling assault on a new frontier. Vast sums of 
money are being appropriated by the federal govern- 
ment for this exciting venture. Large numbers of the 
keenest brains in the country are working on solutions 
to its difficult and complex problems. Many of the 
nation's corporations are expending time, facilities, 
and manpower on space hardware. Colleges and 
universities are developing new curricula and re- 
search projects. Members of Congress and military 
commanders are searching for answers to the political 
and military problems generated by space activities. 
Radio, television, and newspapers are providing great 
amounts of broadcast time and printed pages to 
cover and explain space-age achievements. 

With all this discussion, dialogue, and debate cen- 
tering around the need to conquer space, it is desir- 
able to review the reasons for its exploration. 

Quest for Knowledge 

The one reason most generally accepted by the 
public is the scientist's "need to know." Research gives 
the necessary impetus to progress. New knowledge 
now accruing from space research will be translated 
tomorrow into benefits for all mankind. 

The quest-for-knowledge concept was defined by 
President Eisenhower when he stated: 

"Scientific research has never been amenable to 
rigorous cost accounting in advance. Nor, for that 
matter, has exploration of any sort. But if we have 
learned one lesson, it is that research and exploration 
have a remarkable way of paying off— quite apart 
from the fact that they demonstrate that man is alive 
and insatiably curious. And we all feel richer for 
knowing what explorers and scientists have learned 
about the universe in which we live." 

There have already been some practical gains, e.g., 
new metals and ceramics and better weather fore- 

casting, but it is probable that the greatest advances 
from space research are still unseen and unknown. 

Peaceful Uses 

A second important reason for public acceptance 
of the responsibilities and sacrifices imposed by space 
exploration is the realization that the goals are funda- 
mentally peaceful. Even though the nation is gaining 
knowledge essential to the national security, the 
peacetime benefits, present and potential, are tre- 

Mr. James E. Webb, Administrator of the National 
Aeronautics and Space Administration (NASA) re- 
ports, "New knowledge is needed in almost every 
branch of science and technology. Outer space is our 
newest frontier and in this dawning era we can 
broaden man's horizons. Our Space Agency is a 
research and development organization, dedicated 
to the acquisition of knowledge and its dissemination 
for peaceful and scientific purposes to benefit all 

To accomplish this goal of peaceful penetration of 
space, the United States shares much of its knowledge 
and information with scientists of approximately 
twenty friendly foreign countries. At the same time, 
NASA is entrusted with the task of supervising the 
expenditure of over one billion dollars a year. More 
than 85 per cent of this NASA budget is distributed 
in work and research contracts negotiated with in- 
dustry and universities. There are now over 5,000 
organizations engaged in the missile-space industry. 

President Kennedy summed up the public view 
on this subject when he stated that the American 
efi^orts were planned "to invoke the wonders of science 
instead of the terrors . . ., to explore the stars, to 
conquer the deserts, eradicate disease, tap the ocean 
depths and encourage the arts and commerce." 


National Security 

Even though this nation's primary emphasis is on 
the peaceful products of space exploration, there can 
no longer be any doubt of the military implications of 
the "space race." One of the objectives in the Act 
which created NASA, passed by Congress in 1958, 
was "the making available to agencies directly con- 
cerned with national defense of discoveries that have 
military value or significance, and the furnishing by 
such agencies, to the civilian agency established to 
direct and control nonmilitary and space activities, 
of information as to discoveries which have value or 
significance to that agency." 

No one can, at the present time, forecast all of 
the military applications of space technology. How- 
ever, aerospace power of the United States is the Free 
World's key to future military security; consequently, 
the control of space becomes necessary to the future 
safety of the nation. 

National Prestige 

An added factor, but one difficult to measure, is 
that of national prestige. The Soviet Union has been 
exceptionally skillful in the exploitation of its space 
achievements for propaganda purposes. The success- 
ful orbital flights of the Cosmonauts Gagarin and Titov 
undoubtedly contributed greatly to Russian prestige 
throughout the world. Many in the United States 

believe that this country's space efforts are a gauge 
of its vitality and its capacity to counteract rival in- 
fluences, as well as a criterion of the nation's ability to 
maintain a technological and scientific greatness 
worthy of the trust and confidence of other free 

In the international-prestige feature of the space 
race, at least its early stages, the United States was 
in a runner-up position. The Soviet successes have 
been spectacular, but when the following figures are 
studied and the exploits of Astronaut Glenn added, 
it is obvious that this nation has made notable gains 
and is now forging ahead. (See Figure 145.) 


Earlh Lunar Solar 

Satellites Impact Orbit Total 

United States 

Spacecraft Orbited 


Spacecraft Orbited 

U. S. Spacecraft Now 
in Orbit 

Russian Spacecraft 
Now in Orbit 

figure M5 — The NASA Mercury-Redstone III is stiown during llie early 
morning hours of May 5, 1961, os it was being readied for flight. The 
booster ploced Astronaut Alan B. Shepard, Jr., inside a Project Mercury 
spacecraft into a 5,100 mile per hour flight 302 miles downrange. 
(Courtesy Notional Aeronautics and Space Administration.) 

*As of November 15, 1963, Space tog, TRW Space Technology 
Laboratories, p. 40. 

It can be understood both from the above figures 
and the following description of the many American 
space projects that this country's broad scientific en- 
deavors have shown outstanding results. 

Current Space Activities 


The Explorer series originated the space exploration 
program of the United States. The first Explorer, 
which was launched in January 1958, produced in- 
formation leading to the discovery of the Inner Van 
Allen radiation belt and recorded the first micro- 
meteorite observations in a satelUte. Subsequent 
Explorer satellites have continued to investigate the 
Inner and Outer 'Van Allen radiation belts, micro- 
meteorite energy, and, in addition, solar winds, inter- 
planetary magnetic fields, and distant areas of the 
earth's magnetic field. 

Explorer VII, which is one of the two satellites 
still active, was nicknamed the "Kitchen Sink" when 
it was launched in October 1959 because of the large 


number of scientific instruments it carried. Explorer 
VII has solar batteries which generate the necessary 
electricity for the satellite's operation. 

Explorer XII, which was launched from Cape 
Canaveral in August 1961, has relayed information 
which is causing a reappraisal of the Inner and Outer 
Van Allen radiation belts discovered by earlier Ex- 
plorer satellites. Scientists now feel that a single 
belt begins about 400 miles out from the equator 
and extends to a maximum of 24,000 to 28,000 miles. 
No definite outer boundary can be established as the 
solar winds constantly shift the radiation belt's 
frontier. Currently, the Van Allen belt is named the 
magentosphere. Through January 1, 1964, a total of 
21 Explorer satellites had been successfully launched. 


Beginning in October 1958, a total of five shots 
were made in the Pioneer series. Although Pioneers I, 
II, and III did not reach their objectives, i.e., earth- 
moon trajectories, they did provide much new scien- 
tific knowledge concerning radiation hazards, the 
density of micrometeorites, and measurements of the 
interplanetary magnetic field. 

Pioneer IV, however, was considered a major 
achievement during the early years of space explora- 
tion. In March 1959, Pioneer IV was launched on 
an earth-moon trajectory. Although this space probe 
reached the vicinity of the moon, it did not come 
within the 20,000-mile range which would have per- 
mitted a photoelectric sensor to sample the moon's 
radiation. Pioneer IV passed within 37,300 miles of the 
moon and continued on into orbit around the sun, 
where it is expected to remain for millions of years. 
It is also noteworthy that Pioneer IV was tracked for 
a distance of 407,000 miles before contact was lost. 

Pioneer V was considered an even more spectacular 
accomplishment. This space probe was launched in 
March 1960 and went into orbit around the sun where 
it, too, is expected to circle for millions of years. 
Pioneer V was designed to investigate space between 
orbits of earth and Venus, test extreme long-range 
communications, and study methods for checking the 
Astronomical Unit and other astronomical distances. 
At present, a total of seven launches are scheduled. 
Pioneer VI will probably be launched in 1965. To 
date, the Pioneer program has achieved all of its 
major projects and transmitted vast amounts of useful 
information. In addition, this interplanetary probe 
recorded the most distant radio transmission from 
the earth, more than 22 million miles. 

In December 1958, another earth satellite with the 

code name Project Score was placed in orbit. Although 
the satellite remained in orbit only 34 days, it relayed 
a great amount of scientific information. 

The objectives of Project Score were to test a variety 
of combinations of voices and teletype communications 
between ground and satellite stations and to confirm 
the feasibility of using courier satellites. Project Score 
is best remembered for the broadcast of President 
Eisenhower's Christmas message to the world. This 
particular transmission and reception was the first 
time a human voice had been received from outer 


In February 1959, the first in a long series of Dis- 
coverer satellites was launched. As of February 1962, 
38 Discoverer launchings had been attempted and 
26 had been successful. 

The primary mission of the Discoverer series has 
been to develop ability to launch satellites consistently 
into a precise, near circular, polar orbit; stabilize and 
control an object in orbit; maintain space-ground 
communications; and separate a capsule, bring it 
back to the earth, and recover it. This fourth mission 
has been highly successful. There have been 26 at- 
tempted capsule recoveries, of which eight have been 
successful mid-air recoveries and four successful 
ocean recoveries. 

In December 1961, Discoverer XXXVI was launched 
from Vandenberg Air Force Base in California. This 
Discoverer carried something new— a ten-pound robot 
named Oscar. Oscar, a code name for Orbiting Satel- 
lite Carrying Radio, was built by amateur radio 
operators to broadcast transmissions to ham operators 
around the world. In January 1962, Discoverer XXX- 
VII was launched but failed to orbit. However, Dis- 
coverer XXXVIII, launched the following month, did 
go into orbit. Following the launch of Discoverer 
XXXVIll, the Department of Defense adopted a 
policy of releasing only basic information on military 
launches. Consequently, Discoverer Satellites are no 
longer individually identified. 


The initial attempt to launch a Transit satellite 
occurred in September 1959. Although Transit lA 
failed to achieve orbit. Transit IB was successfully 
launched from Cape Canaveral in April 1960. 

The primary purposes of the Transit satellites are 
to develop, test, and demonstrate navigational equip- 
ment which would reliably determine the position 
of all surface craft, aircraft, and submarines. In addi- 
tion, they would provide for a more accurate, all- 


weather air and sea navigation system than is presently 

Transit 2A was unique in that it carried, and placed 
into orbit, a "piggy back" satellite which has been 
named Greb, a slight code-name misspelling of Galac- 
tic Radiation and Beta. Transit 4A carried two piggy- 
back satellites which, although successfully ejected, 
did not separate; nevertheless, they are still trans- 
mitting data on certain experiments. Transit 5A, an 
operational, navigational system for Polaris submarines 
was successfully launched on December 18, 1963. 


The Television and Infrared Observation Satellite 
(TIROS) was the first NASA meterological satellite 
project. In April 1960, the first of eight Tiros satellites 
was launched. Tiros I, a camera-carrying picture- 
taking satellite, provided the weatherman with a new 
dimension for weather prediction. The two television 
cameras have relayed over 22,000 pictures to weather 
scientists around the world. 

Tiros II was placed into orbit in November 1960 
and Tiros III in July 1961. (See Figure 146.) All three 
satellites are expected to remain in an earth orbit for 
many decades, and since the top and sides of these 
pill-box shaped satellites are covered with solar cells 
which transform sunlight into electricity, they will 
continue to measure the earth's cloud cover and to 
transmit pictures. Tiros IV, V, and VI were launched 
into an earth orbit during 1962. Eight Tiros satellites 
have now been successfully launched with a ninth 
scheduled for the summer of 1964. 

Figure 146 — This is NASA's solellite TIROS III. This Tiros differs from 
earlier Tiros satellites in thol it carries two wide-angle cameros and on 
odditionol infrared experiment. (Courtesy NASA.) 

Although the Tiros series has been a highly suc- 
cessful experiment, the satellites are not in them- 
selves operational weather systems. (See Future Space 
Projects. ) 


The Missile Defense Alarm System satellite 
(MIDAS) was designed to provide the United States 
with a military satellite system capable of detecting 
the launch of an aggressor ballistic missile within 
seconds after lift-off. Although Midas I, launched 
in February 1960, failed to orbit, Midas satellites II, 
III, and IV have since been successfully injected into 
a nearly circular earth orbit. 

An interesting feature of the Midas satellite is that 
after attaining its 18,000 mph orbital speed, the atti- 
tude of the satellite is changed from the horizontal 
to a nose-down position. Its shape is basically a 
cylinder, with one end pointed. It is this pointed end 
which is continuously aimed at the earth and which 
contains the infrared sensors which detect the tremen- 
dous heat generated by missile boosters at the time 
of launch. The Midas satellites, weighing close to 
3,500 pounds, are the largest objects to have been 
placed in orbit by the United States. 


A man-made star, given the code name Echo I, was 
launched in August 1960. It is an inflated sphere, 100 
feet in diameter, made of mylar polyester plastic about 
one-half the thickness of the cellophane on a package 
of cigarettes, and is still in orbit. Because this com- 
munications satellite can be seen by the naked eye, it 
has probably created more public interest than any 
other unmanned shot. 

Echo I was an experiment in a passive communica- 
tions satellite, and its only mission was to serve as a 
relay point for bouncing messages from one point on 
the earth to another point. Except for two very tiny 
transmitters which are powered by solar cells, it was 
unique in that it carried no instruments. Echo II was 
launched in January 1964. It is being used as a passive 
reflecting sphere for joint US-USSR experiments. 


From October 1960 to November 1961, three at- 
tempts were made to launch a Satellite and Missile 
Observation System (SAMOS). Only Samos II was 
successfully orbited. Its programmed life span was 
relatively short. Samos II was launched in January 
1961 and its transmitters faded in March 1961. 

The Samos satellites were designed to scan the 
entire surface of the earth, and, in addition, to study 


cosmic rays, the earth's electrical field, and micro- 
meteorites. The details of the results of the various 
Samos II experiments have not been made public. 
It is known, however, that the picture-taking, world- 
wide reconnaissance satellite was sponsored as a 
military program and was a follow-up to the Midas 
satellite series. During 1964, NASA/DOD plan a joint 
effort to continue the Midas and Samos projects. 

Lunar and Interplanetary Launchings 

The next logical step in the effort to achieve space 
capability is, first, to probe the atmosphere surround- 
ing the moon, then to make an impacted or "hard" 
landing followed by a controlled or "soft" landing, 
and finally, after an instrumented exploration of the 
moon's surface, to make a manned lunar landing. The 
attempt to reach the moon with unmanned satellites 
has been divided into three stages. These have been 
given the code names of Ranger, Surveyor, and 


In August 1961, Ranger I, the initial effort of the 
United States in moon exploration, was launched from 
Cape Canaveral to flight test lunar spacecraft. Both 
Rangers I and II were designed to seek information 
concerning attitude control, solar and battery power 
supplies, communications equipment, estimates of the 
probable lifetime of equipment in a space operation, 
and data on the composition of materials and gases 
beyond the earth's atmosphere. 

Ranger III was to have studied the possibilities of 
landing a package on the moon and to have developed 
studies of lunar environment. It was launched in 
January 1962, but, due to excess velocity given by 
the Atlas booster, the spacecraft missed the moon 
by over 22,000 miles and continued on into space to 
become a satellite of the sun. Rangers IV and V 
were launched in April and October of 1962. They 
were assigned the same program objectives and ex- 
periments as Ranger III. 

Ranger VI was launched on January 30, 1964. It 
impacted on the surface of the moon; however, its TV 
system failed and consequenriy a great deal of in- 
valuable data was not transmitted to the various 
earth receiving stations. A total of nine spacecraft 
launches are planned prior to an attempted manned 
lunar landing. 


A launch schedule, beginning in 1965, or possibly 
late 1964, has been established for the Surveyor series 
Surveyor spacecraft will attempt a soft or con- 

trolled lunar landing. It is expected that Surveyors 
will carry 100 to 300 pounds of scientific instruments 
designed to examine the magnetic lunar field, the 
atmosphere of the moon, and its surface and subsur- 
face characteristics. The spacecraft will carry a drill 
which will dig and analyze samples of the lunar 
surface. A successful Surveyor will also choose the 
eventual site for a manned landing, via television 
search and by depositing a radio beacon which future 
spacecraft can use as a "Moon approach beam." (See 
Figure 147.) 


During the same period that the moon was being 
explored, interplanetary probes by Mariner spacecraft 
were launched. A Mariner II spacecraft investigated 
interplanetary space between earth and Venus in 
1962. The e.xperiments which were carried out by 
this satellite determined the temperature on the 
planet's surface, the Venusian magnetic field, and the 
atmospheric composition. A total of twelve shots are 

The Voyager project is similar to the Surveyor series 
except that Voyager spacecraft will explore the planet 
Venus, first by orbit, then by placing a capsule on 
the surface of the planet Venus. While the capsule 
records measurements on the surface of the planet, 
the mother spaceship will continue to orbit it at an 
altitude of several hundred miles transmitting data 

Figure 147 — Full-scole model of Surveyor satellite. Surveyor 
uled to moke soft landing on the moon. (Courtesy NASA.) 


on the atmosphere. The initial launch is scheduled 
for 1967. 

Future Space Projects 


In the meteorological field, Nimbus and Aeros satel- 
lites are planned. Nimbus satellites, scheduled for an 
early 1964 launching, will be placed into a polar orbit 
and will be able to provide weather information 
from every point on the earth's surface every six 
hours. Aeros satellites will also be earth-oriented and 
will be placed in a circular stationary orbit. Three 
Aeros satellites, properly spaced around the surface 
of the earth, will be able to monitor global weather 
conditions continuously. 


In the field of world-wide communications, the 
United States has developed the Relay, Telstar and 
Syncom projects. 

Relay was placed in orbit in 1962 and Relay II in 
1964. These satellites will have as their primary mis- 
sion the reception and transmission of television, tele- 
phone, and other wide-band forms of communication. 
Telstar I and II satellites are a commercially spon- 
sored series which will also be used to develop new 
information on television, telephone, and radio trans- 
missions. Both Relay and Telstar will be relatively 
low-altitude earth satellites. 

Syncom II went into orbit at an estimated 22,000- 
mile altitude in July, 1963. Like the Relay and Telstar 
satellites, Syncom is an active-repeater satellite, 
unique in that its orbital pattern will follow a "figure- 
eight" conformation, constantly monitoring activities 
along the east coast of the United States only. 

The Advent satellite will also be injected into orbit 
at approximately 22,000 miles but, unlike the Syncom 
which will orbit in a figure-eight path, it will be given 
a speed which will be synchronized with the earth's 
speed, thus permitting the satellite to remain in a 
stationary position. First flights are scheduled for the 
1966-1968 period. 


The Orbiting Solar Observatory (OSO), Orbiting 
Astronomical Observatory (OAO), and Orbiting Geo- 
physical Observatory (OGO) projects are developing 
a great deal of scientific interest. The first OSO 
satellite was successfully placed in orbit on March 7, 
1962. A second launch is scheduled for 1964. This 
458-pound laboratory will help to answer such ques- 
tions as how the sun affects weather conditions, how 

radio and television communications are influenced 
by bombardment in the ionosphere, and the extent of 
the Van Allen belt. 

OAO satellites will be of primary interest to astron- 
omers. It is planned that the satellite will carry tele- 
scopes to aid the study of deep space not presently 
observable because ground observations are obscured 
by the earth's atmosphere. OAO satellites are sched- 
uled for launch in 1965 and, in addition to telescopes, 
will carry large reflecting mirrors, solar batteries, and 
video tubes to test ultraviolet rays. 

OGO satellites will be devised so that they can 
conduct up to 50 geophysical experiments in one 
flight. Planned experiments now include investigation 
of terrestrial phenomena, the physics of fields and 
energy in space, solar elements, gravitation, and micro- 
meterorites. OGO will be positioned so that it always 
points at the earth; however, certain instruments lo- 
cated on the solar paddles will point toward the sun. 
A total of six flights are planned with the first launch 
to be in 1964. 

Man in Space 

Sometime prior to 1970, Phase ill of the Apollo 
project will have been completed. This will land a 
lunar spacecraft, carrying three people, on the moon, 
conduct numerous experiments, and return to the 

Just as the unmanned satellites were a vital step 
in the progression to a manned lunar shot, so the 
X-15, Mercury, and Gemini projects are necessary 
preliminary requirements to the Apollo effort. 


Beginning with the X-1 rocket plane, which Major 
Charles Yeager, USAF, flew in 1947 faster than the 
speed of sound, much experimental and scientific 
data have been compiled which are of major assistance 
to the man-in-space program. The X-series of rocket 
planes, presently represented by the X-15, have tested 
the higher altitudes where the air is so thin and cold 
that a man would die within a few seconds if he 
were not wearing a spacesuit. Information gained 
from friction and heat developed by high-speed craft 
have aided the Mercury Project designers and will be 
of valuable assistance to Gemini and Apollo scien- 
tists. G-load testing has given some indication of both 
pilot and aircraft operational control and proficiency. 
New ways to control the attitude of the rocket plane 
have been developed, since the plane was designed 
to fly at an altitude which would leave 99 per cent 
of the atmosphere behind. 


The X-15, flying almost outside the earth's atmos- 
phere, has provided a study of the effects of radiation 
on the human body, along with much useful informa- 
tion on the survival of man in space. In addition, 
air-conditioning systems have been tested, communi- 
cations improved, and new instruments planned. The 
list of experiments attempted and the amount of 
knowledge acquired from X-15 flights has been sub- 
stantial. Possibly the reentry information, physiological 
and psychological data, and improved rocket engine 
performance and fuel knowledge have been among 
the most significant experiments of the X-15 program. 

The X-15 research program was started in 1952 
when the National Advisory Committee for Aero- 
nautics (NACA), the immediate predecessor of NASA, 
began laboratory studies on manned hypersonic flight 
at high altitudes. In 1954, NACA established the 
basic performance requirements for the research air- 
plane and in 1955 North American Aviation, Inc. was 
awarded a contract to build three X-15's. 

The X-15 is a comparatively small airplane, 50 
feet long, with a 22-foot wing span. The outer body 
of the craft is made of a special metal, a nickel- 
chrome-iron alloy, named Inconel X, with an inner 
layer composed of a stainless-steel and titanium alloy. 
This special skin is not only strong but can protect 
the plane and the pilot in temperatures up to 1,200 
degrees Fahrenheit. The vehicle is painted with an 
unusual chemically composed black paint which re- 
sists fire, absorbs heat, but still holds together at 
temperatures up to a thousand degrees. The rocket 
engine has been designed to generate more than 
400,000 hp, and although it requires less than IV2 
minutes to consume its fuel load, the X-15 has been 
able to achieve an altitude of approximately 354,000 
feet and a speed of over 4,000 mph. The X-15's sci- 
entific contributions in the areas of aeromedicine, 
aerodynamics and structural heating, hypersonic 
stability and control, and piloting problems are a 
major factor in the successful suborbital and orbital 
flights programmed under the direction of Projects 
Mercury and Gemini. The X-15 and X-15A2 programs 
are expected to continue through 1968. 


Project Mercury became an official program in 
America's assault on space in October 1958. Its scien- 
tific objective was to determine what man's capabil- 
ities would be in a space environment and his reactions 
while being subjected to entering into and returning 
from space. To accomplish this scientific objective 
successfully, NASA decided it would be necessary 
to put a manned space capsule into orbital flight 
around the earth, recover the capsule and its occupant 

successfully, and analyze the scientific information 
resulting from this flight. The Project was terminated 
upon the successful completion of Maj. Gordon 
Cooper's 22-orbital flight. The general objectives were 
attained when Lt. Col. John H. Glenn, Jr., USMC, 
completed three orbits of the earth on February 20, 

The initial flight of the man-in-space program was 
accomplished by Navy Lt. Com. Alan B. Shepard, Jr., 
when he completed a suborbital flight in May 1961. 
(See Figure 148.) His achievement was quickly fol- 
lowed by a similar one made by Capt. Virgil I. Gris- 
som, USAF, in July 1961. 

A first step in the Mercury Project was the selection 
of the Astronauts. Hundreds of applications were 
submitted and, following strenuous physical and 
psychological tests, seven former test pilots were 
chosen in April, 1959: Lt. Malcolm S. Carpenter, USN; 
Capt. Leroy G. Cooper, USAF; Lt. Col. John H. Glenn, 
Jr., USMC; Capt. Virgil I. Grissom, USAF; Lt. Cdr. 
Walter M. Schirra, USN; Lt. Cdr. Alan B. Shepard, 
Jr., USN; and Capt. Donald K. Slayton, USAF. 

These men were chosen because of their exceed- 
ingly high intellectual ability and physical fitness. All 
seven Astronauts have considerable technical knowl- 
edge in astronomy, navigation, mechanics, and other 
basic sciences. Prior to being chosen, all were care- 
fully checked on their ability to sustain stresses such 
as high altitude, pressure, motion, heat, and loneliness. 

When the training program for the Astronauts was 
started, many difficulties had to be resolved since 
a similar training schedule did not previously exist. 
As the program developed, the training schedule was 
divided into five major categories: (1) academics, 
(2) static training devices, (3) dynamic training de- 
vices, (4) egress and survival training, and (5) 
specific mission training. 

The academic phase consisted of lectures and 
studies in the scientific fields of mechanics, aerody- 
namics, astronomy, meteorology, astrophysics, geo- 
physics, space trajectories, rocket engines, and 
physiology. In addition, there were many detailed 
briefings on the launch vehicle, the capsule, and their 

The static training devices tested and improved 
the Astronauts' knowledge of retromaneuvers and 
reentry maneuvers. There was extensive instruction in 
the function and operation of the instrument panel. 
Their ability to control the flight attitude of the 
spacecraft was tested by a machine named ALFA 
(Air Lubricated Free Attitude) Trainer, and their 
navigational ability was improved by installing a 
Link Trainer in a planetarium so that they could 
practice navigation by the stars. 







A. Escape rockets, tower jettison rockets, and es- 
cape tower provide safe recovery of vehicle 
in cose of booster malfunction. 

B. Antenna housing for ground command, telem 
eiry and voice antennas; six-foot drogue para- 
chute; and infrared horizon sconners for 
attitude reference. 

C. Recovery compartment contains the 63-foot 
diometer main and reserve parochutes; re- 
covery beacon antennas; flushing recovery-aid 

Crew compartment contains major spacecraft 
systems, including communications, electrical 
power, environmental control, instrumenlolion, 
navigation oids, stabilization and control. 

E. Retrogrode package contains three retrograde 
rockets for initiating the spocecroft's return 
from orbit; ond three rockets for separating 
the spacecraft from the booster after orbital 
velocity is reached. 

F. Heat shield provides protection for the astro- 
naut from the extreme temperatures experi- 
enced during re-entry. 


The dynamic training devices gave tlie Astronauts 
some experience in weightlessness by flying aircraft 
through a paraboHc trajectory. This instruction was 
followed by centrifuge training or high-g training, 
where several of the men were able to withstand 
accelerations up to 18g without apparent difficulty. 
Another interesting training device was the MASTIF 
(Multiaxis Spin Test Inertia Facility). The Mastif 
trainer revolved around all three axes, i.e., pitch, roll, 
and yaw. The Astronaut, by using an exact replica of 
the Mercury capsule control panel, was taught to 
control the flight path. (See Figure 149.) In addition, 



side hatch 
ihstrument\ window 



/— iMM /rtiTirrrti 

^^^'^n/- MENTAL 


Figure 149 — Project Mercury, Ballistic Missile. (Courtesy of NASA.) 

since all of the men were qualified jet pilots, they felt 
that it was vital to continue their proficiency as pilots 
because they were then able to maintain their sharp- 
ness in making rapid judgments and reactions. 

Egress and survival training provided an adequate 
amount of proficiency should the Astronaut not be 
rescued within a reasonable period. The space capsule 
was dropped into the ocean and both open sea and 
underwater egress were practiced. During this same 
period, both water survival and desert survival tech- 
niques were acquired. 

Specific mission preparation consisted of special 
instruction for a particular mission in an indivdual 
spacecraft and launch vehicle. From the time that the 
spacecraft arrived at Cape Canaveral until it was 
launched, the Astronaut lived with it. He participated 
in all the check-out procedures, attended all meetings 
concerned with the check out and modification of 
the craft, and practiced his specific mission flight plan 
in a procedures trainer. When the spacecraft was 
moved to the launching pad, there were additional 
countdowns and radio checks to be made, and emer- 
gency rescue procedures to be practiced. This final 

training program took about eight weeks and was 
successfully completed when the man and the machine 
were launched from the earth's surface and were 
safely returned. 

Since there was such a vast amount of knowledge to 
be learned, it is not possible for each Astronaut to be 
completely expert in every area. It was therefore nec- 
essary to have each Astronaut assume the responsibil- 
ity for certain areas: 

Carpenter * Navigation and navigational aids 

Cooper ir Redstone launch vehicle 

Clenn * Crew space layout 

Grissom * Automatic and manual attitude 

control system 

Schirra * Life support system 

Shepard * Range, tracking, and recovery 


Slayton * Atlas launch vehicle 

This new type of training program produced out- 
standing results. The suborbital flights of Shepard and 
Grissom, followed by the orbital flights of Glenn, Car- 
penter, Schirra and Cooper advanced the space flight 
capability of the United States to the point that 
manned lunar and interplanetary flight is now planned. 
Although the flights themselves were spectacular, the 
long-range values will stem from the scientific and 
research data which was obtained. 


In September 1962, the National Aeronautics and 
Space Administration (NASA) released the name of 
nine men who had been selected for Gemini and 
Apollo missions. The nine new "astronaut candidates" 
were: Neil A. Armstrong, a NASA test pilot; Maj. 
Frank Borman, USAF; Lt. Charles Conrad, Jr., USN; 
Lt. Com. James A. Lovell, USN; Capt. James A. Mc- 
Divitt, USAF; Elliott M. See, flight test engineer; 
Capt. Thomas P. Stafford, USAF; Capt. Edward H. 
White, USAF; and Lt. Com. John W. Young, USN. 
These men were selected from over 200 military and 
civilian test pilots. 

The first two-man space team was announced in 
April 1964. Astronaut V. I. (Gus) Grissom and Astro- 
naut Candidate John W. Young were chosen as the 
first team and Astronaut Walter M. Schirra and Astro- 
naut Candidate Thomas P. Stafford were selected as 
the backup crew. 

In April 1964, Project Gemini became operational 
with the successful firing and orbiting of an unmanned 


Gemini capsule. A second unmanned test flight was 
scheduled for August 1964. 

After the two unmanned tests are completed, NASA 
plans an additional ten Gemini flights to test manned 
orbital flights and finally manned flights with ren- 
dezvous and docking missions. 

The Gemini spacecraft will be similar in appear- 
ance to the Mercury capsule, although Gemini will 
weigh twice as much as Mercury and will be about 
one-fifth larger. (See Figure 150.) Gemini wiU also 
differ from Mercury in its reentry and landing 
methods. While the Mercury capsule, after reentering, 
was parachuted to the earth, Gemini spacecraft will 
have an inflatable, steerable device, resembling a bat's 
wing, to guide it to the ground. 


Project Apollo research and development is cur- 
rently in the mock-up stage. Prior to the Project's final 
goal of a multi-manned landing on the moon and a 
safe return to earth, there will be several intermediate 

The first step will be to fly the three-man spacecraft 
in an earth orbit. This flight will permit the testing of 
the equipment and systems, the training of the crew, 
and the development of operational techniques. Fol- 
lowing the earth orbital flights, the craft will be flown 
longer and longer distances from the earth. 

The final step before a moon landing will be to 
make several orbits of the moon, conducting numerous 
scientific experiments pertaining to the guidance and 
control tasks that would be needed in the lunar land- 
ing mission. 

Although the final Apollo spacecraft configuration 
has not been established, safety of flight will be of 
utmost importance and will be a major influence on 
the ultimate design. One of the most difficult prob- 
lems still to be solved is the development of a power- 
ful launch vehicle for the capsule. Saturn booster 
rockets are now being tested. Saturn launch vehicles 
will be capable of providing 1,500,000 pounds of thrust 
and will have the power to send a 90,000-pound pay- 
load to the moon. 

Peaceful Applications of Space Research 

One of the most obvious and continuing values of 
America's space effort is the economic benefit. A large 
percentage of the federal budget is being spent by 
contracting with industry for new research and new 
product development. The government's expenditures 
are not being limited to one field only. The entire 
industrial spectrum is used; e.g., electronics, metals, 
fuels, machinery, plastics, instruments, textiles, paints, 
and even foods. The economic benefit is a general one 

Figure 150 — Mockup of o Project Gemini spacecraft. (Courtesy of Mc- 
Donnell Aircroft Corporation.) 

which improves the health and well-being of the na- 
tion's economy. But there are also some specific ad- 
vantages to the individual. 


Although communications satellites are still in the 
research and development stage, the potential world- 
wide coverage of television, telephone, and radio is 
enormous. The experiments being conducted with the 
aid of Echo and Telstar Satellites presage success- 
ful and broadened broadcast ability. 

Echos I and II have already proved that voice 
transmission can be extended to intercontinental 
ranges. Two-way telephone conversations have been 
held. In August 1960, the first transatlantic wireless- 
code was transmitted between the United States and 
France by bouncing the signal off the reflecting skin 
of Echo I. Wire photos have also been sent and re- 
ceived. When enough earth satellites have been 
properly positioned, world-wide transmissions will 
become a reality. 

The advantages of a world-wide communications 
net are evident. The efficiency and effectiveness of 
transmissions would be improved, since atmospheric 
magnetic storms would not affect their operations. 


On-the-spot news coverage and "live" programs would 
assist the nations of the world in a better understand- 
ing of the customs and habits of other countries. Edu- 
cational TV would be available in a wider area and 
would not be dependent upon weather conditions. 
Hi-fidelity radio and long-distance phone calls would 
be available to everyone at much less cost. 


Meteorologists have stated tliat their inability to 
predict weather conditions accurately stems from their 
lack of adequate data. With present equipment, about 
20 per cent of the earth's surface is regularly observed. 
The Tiros satellites have greatly added to the amount 
of knowledge now available to scientists on cloud 
coverage. Many researchers feel that once accurate 
weather prediction becomes commonplace, then some- 
thing can also be done to change the weather. 

The benefits of long-range accurate forecasts could 
be immeasurable. Farmers would be able to take ad- 
vantage of the best days for planting and harvesting- 
even determine the best crops to plant. Hurricanes and 
tornados might be dissipated before they became de- 
structive. Vacations could be better planned. Floods 
and other natural disasters could be foreseen and nec- 
essary countermeasures thus prepared. 

The significance of correct weather forecasting was 
outlined in a study by the House of Representatives 
Committee on Science and Astronautics. The report 
stated, "An improvement of only 10 per cent in ac- 
curacy could result in savings totalling hundreds of 
millions of dollars annually to farmers, builders, air- 
lines, shipping, the tourist trade, and many other 
enterprises. " 


In experimenting with foods for space use, nutri- 
tionists have discovered new methods for their prepa- 
ration and preservation, particuarly the development 
of synthetics and the infrared blanching of foods, 
which is an improved way to prepare them for freez- 
ing or canning. 

The research on temperature control can lead to 
more economical and efficient home heating. For the 
housewife, scientists have developed a new material 
for pots and pans named Pyroceram. Pyroceram, which 
can be taken from the refrigerator and immediately 
placed over the hottest flame, was originally proposed 
for use as a nose-cone material. 

Miniaturization of instruments, caused by the need 
to conserve both weight and space in the space cap- 
sule, may eventually provide the well-known two-way 
wrist watch radio of the "Dick Tracy" comic strip. 

By evolving new ways to check the physical and 

mental health of the Astronauts, doctors and medical 
technicians have developed new technicjues and in- 
struments to measure heart action, brain waves, blood 
pressure, breathing rate, and other physiological re- 
sponses. A new drug, which is a by-product of a 
missile propellant, is now being used to treat mental 
ills. In addition, a means to lower blood temperature 
during operations and a miniature heart stimulator 
and a small valve which could replace the valve in 
the human heart are now in the testing stage. 

Industry is making use of new plastics and metal 
alloys to replace iron, steel, aluminum, etc. Newly dis- 
covered silicones, polyesters, resins, asbestos, graphite 
cloth, and glass fibres have proved to have far more 
mechanical strength than many common construction 
materials. New sources of power are being investi- 
gated. Scientists believe that it will eventually be 
possible to substitute solar batteries, gaseous fuel cells, 
and lightweight nuclear reactors for the present gas, 
oil, and coal power sources. 

Transportation and navigation may soon progress 
to the point where they are not affected by the 
weather. Research data from both the Tiros and 
Transit series of satellites will make it possible for 
planes and ships to avoid inclement weather and to 
pinjx)int exactly their geographic location. 

The new products and the new developments of 
space research and technology are numerous and 
varied. The by-products and new incentives of the 
Aerospace Age, as Dr. Hugh L. Dryden, NASA's 
Deputy Administrator said, are "perhaps the greatest 
economic treasure . . . This new technology is ad- 
vancing at a meteoric rate. Its benefits are spreading 
throughout our whole industrial and economic sys- 
tem." Many new jobs have been created. It is esti- 
mated that the aerospace industry is now the largest 
manufacturing industry in the United States. As an 
employer, it has approximately 1,200,000 employees. 


The space program of the United States, which 
began with the successful launching of Explorer I in 
January 1958, has achieved many spectacular suc- 
cesses in a very short period of time. Although there 
have been many military applications and uses of 
space technology, the primary American emphasis has 
been on peaceful developments. 

The United States has planned and carried out a 
variety of scientific experiments with its satellite pro- 
gram. Communications, weather, navigation, lunar and 
interplanetary probing, missile warning, missile re- 
covery, mapping, and observation satellites have been 
launched. All of the satellite projects have added to 


the knowledge which will permit both lunar and inter- 
planetary landings within the near future. 

The X-series of experimental aircraft have provided 
much needed information to conclude successfully 
the Mercury flights. Knowledge concerning air con- 
ditioning, temperature control, and communications 
equipment is important. However, the greatest con- 
tributions of the X-15 project to the space program 
have been in the areas of physiological and psycho- 
logical data, and in improved engine performance and 
fuel information. 

Project Mercury was initiated in 1958. After select- 
ing seven men to begin training as the nation's first 
Astronauts, a new training program was developed. 
Because it was impossible for the Astronauts to keep 

up to date with all of the information required for 
successful space flights, each man became an expert 
in one particular area. The next man-in-space project 
has received the code name of Project Gemini. 
Project Gemini will be followed by unmanned lunar 
and interplanetary launches. Project Apollo's goal is 
to land a manned spacecraft successfully on the moon 
and then have it return safely to earth. 

The peaceful applications of space research are even 
now finding aceptance and use by the public. An en- 
tirely new industry has developed to deal with space 
technology and research. More than 5,000 companies 
are presently engaged in space research or production, 
and there are more than 3,000 useable by-products of 
missile-space science. 


1. What are the five major categories of the Astro- 
nauts' training program? 

2. What new information did Explorer XII ascertain 
concerning the Van Allen radiation belt? 

3. Which unmanned earth satellite created the most 
public interest? Why? 

4. What have been the contributions of the X-15 to 
manned space flight? 

5. What were the two objectives of the Project Score 
satellite? Were they achieved, and, if so, how? 

6. How many people were chosen for Project Mer- 
cury? Name them. 

7. How can accurate weather prediction be of value? 
Which earth satellites assist the meteorologist in 
his forecasts? 

8. What are the major differences between Project 
Mercury and Project Gemini? 

9. What was the scientific objective of Project Mer- 

10. Did Ranger VI accomplish its launch objectives? 
What were those objectives? 

11. What is an OAO satellite and what will it do? 

12. What is Inconel X and what is its use? 

13. Which satellite was nicknamed the "Kitchen 

14. What are Prospector spacecraft designed to ac- 

15. What was unique about the Transit IIA satellite? 

16. Why were Midas satellites launched? 

17. Describe five different by-products of space tech- 

18. What is the significance of the code name Gemini 
when used to describe the next United States 
man-in-space project? 

19. What are the names of the Russian Cosmonauts 
who made orbital flights? 

20. Which launch vehicles are now being tested for 
the Apollo program? What intermediate steps in 
the Apollo Project are planned before a manned 
lunar landing can be accomplished? 



Payload Wt. (lb.) 







Mariner C (2) 
Ranger (4) 
Surveyor (2) 


Solor Observatory (2) 


Explorer (S-66) 

Explorer (IMPB) 

Explorer (5-3C) 



Echo 2 





' 186 














1 ,298-4,606 












Vetiicle-copsule compatibility 

Systems qualification 
Launcli vctiicle test 
Launch vehicle test 
Lounch vehicle test 
Launch vehicle test 


Rough impact 

Vehicle-dynamic payload test 

Study solar radiation 
Study space phenomena 
Study ionosphere from above 
Interplanetary monitoring platforn 
Study energetic porlicles 

Active relay experiments 

Passive Sphere (launched 1/25/64) 

Active Repeater (launched 1/21/64) 

First RSiD flight 
Photograph cloud cover 

•Aviotion Week ond Spoce Technology, McGrow-Hill, Vol. 80, No. 11, March 16, 1964, p. 




August 11-15, 1962 

June 14, 1963 

August 11 15, 1962 

June 14, 1963 

April 12, 1961 

April 12, 1961 

May 5, 1961 

May 5, 1961 

Duration with Earth Orbit 
Commandant A. G. Nikoloev; 
Spacecraft USSR Vostok 3; 
63 orbits around earth. 

Duration with Earth Orbit 

Lt. Col. Voleri Bikovsky; 
Spocecrofl USSR Vostok 5; 
81 orbits around earth 

Distance with Earth Orbit 
Commandant A. G. Nikoloev; 
Spacecraft USSR Vostok 3 

Dislonce with Earth Orbit 

Lt. Col. Valeri Bikovsky; 
Spacecroft USSR Vostok 5 

Greatest Altitude with 
Earth Orbit 

Moj. Yuri A. Gorgorin; 
Spacecraft USSR Vostok 

Greotest Moss Lifted 
with Earth Orbit 
Moj. Yuri A. Gogarin; 
Spacecraft USSR Vostok 

Greatest Altitude without 
Earth Orbit 

Cmdr. Alan B. Shepord, 
USN; Mercury Spacecraft, 
U.S. Freedom 7 

Greatest Moss Lifted without 
Earth Orbit 

Cmdr. Alan B. Shepord, USN; 
U.S. Freedom 7 

94 hr. 09 min. 59 sec. 


Glossary of Aerospace Terms 

Ablation cooling— melting of nose cone materials during 
reentry of space ships or vehicles into the earth's atmos- 
phere at hypersonic speeds. 

Acceleration— the act of increasing speed. 

Accelerometer- an instrument which measures and indi- 
cates the magnitude of accelerations of an aircraft or 
spacecraft in flight and is a direct indication of the 
forces applied to aircraft or spacecraft and their pas- 

Aerobatics— evolutions voluntarily performed with an air- 
craft other than those required for normal flight. 

Aerodynamics — the science that treats of the motion of air 
and other gaseous fluids, and of the forces acting on 
bodies when the bodies move through such fluids, or 
when such fluids move against or around the bodies. 

Aeronautics— the science and art of flight. 

Aeronomy — the study of the upper regions of the atmo- 
sphere where physical and chemical reactions due to 
solar radiation take place. 

Aerospace power— the entire aeronautical and astronautical 
capacity of a nation. 

Afterburner — an auxiliary combustion attached to the tail- 
pipe of certain jet engines in which additional fuel is 
mixed with unused oxygen in the air flowing from the 
jet and burned to increase the change in velocity of the 
gases, thus increasing total thrust. 

Agonic line— an imaginary line over the surface of the 
earth joining all points along which there is no magnetic 

Aileron— a hinged or movable portion of the traihng edge 
of an airplane wing, used to control the motion of the 
airplane about its rolling or longitudinal axis. 

Aircraft — any airborne vehicle supported either by buoy- 
ancy or by aerodynamic action. 

Air density— the ratio of the mass of air to its volume, 
expressed as its weight per unit of volume, e.g., kilo- 
grams per cubic meter. 

Airfoil- any surface, such as an airplane wing, aileron, 
rudder, or elevator designed so that air flowing around 
it produces useful motion. 

Air mass— a large body of air within which the conditions 
of temperature and moisture in any horizontal plane aie 
approximately the same. 

Arctic or polar— an air mass formed in a cold northern 

Cold—SLXi air mass the temperature of which is colder 
than the surface over which it is moving. 

Continental— an air mass foimed over land areas in a 
temperate zone. 

Maritime— an air mass formed over water. 

Tropical— an air mass formed in or near a bopic region. 

Warm— an air mass the temperature of which is warmer 
than the surface over which it is moving. 
Airplane— a mechanically-driven, fixed-wing, heavier-than- 

air craft supported by the dynamic reaction of the air 

against its wings. 

Pusher— an airplane with the propeller or propellers in 
back of the main supporting surfaces. 

Tractor— an airplane with the propeller or propellers in 
front of the main supporting surfaces. 
Airport— a tract of land or water adapted for the landing 

and takeoff of aircraft and providing facilities for shel- 
ter, supply, and repair. 

Approach— an approach channel designated by the 
FAA administrator where adequate facihties are pro- 
vided for instrument approach procedures. 

Traffic— 1. The flow of aircraft within a given airspace, 
or the traffic of aircraft on an airdrome, or a combina- 
tion of these. 2. The passengers, cargo, mail, or bag- 
gage carried by aircraft. 
Airspeed— the speed of an aircraft relative to the air 

through which it is moving. 

Calibrated— the indicated airspeed rectified to compen- 
sate for error in the airspeed indicator or the Pitot- 
static system. 

Indicated— the speed of the airplane passing through the 
air, uncorrected for instrumental errors or errors 
caused by temperature or barometric pressure. 

Indicator— an instument for measuring the speed of an 
aircraft through the air. 

True- the actual speed of an aircraft through the air, 
obtained by correcting the indicated airspeed for 
temperature and altitude. 
Airway— an air route along which aids to air navigation, 

such as beacon lights, radio ranges and direction finding 

facilities, and landing fields are maintained. 
Airworthiness— the quality of an aircraft denoting its fit- 
ness and safety for operation in the air under normal 

flying conditions. 
Algae— unicellular and multicellular plants considered as a 

potential source of food and oxygen in a closed ecologi- 
cal system for space vehicles. 


Altimeter— an aneroid instrument for measuring the height, 
in feet, of an aircraft above sea level or above an aii- 
port of either departure or destination. 
Setting— the setting made on the barometric scale of an 
altimeter so that on landing the instrument pointers 
will indicate the approximate elevation of that airport 
above sea level. 
Altitude— the vertical distance from a given level to an 
aircraft in flight. 

Absolute— the height of an aircraft above the earth. 
Corrected— the actual height of an aircraft above sea 
Amphibian— an airplane designed to rise from and alight 

on either water or land. 
Aneomometer- an instrument for measuring the speed of 


Dihedral— the acute angle formed by the plane of the 

wing and the lateral a.\is of the aircraft. 
Drift—the horizontal angle between the longitudinal a.xis 

of an aircraft and its path over the ground. 
Of attack— the acute angle between the wing chord and 
the relative wind. This angle varies with the attitude 
of the aircraft. 
Of incidence— the angle between the wing chord and 

the longitudinal axis of an airplane. 
Wind correction— the angle between the track of an air- 
craft over the ground and the heading of the aircraft. 
(If intended track or course is being followed, wind 
correction angle and drift angle are equal.) 
Anoxia— absence of oxygen in the blood, cells, or tissue, as 
would be the case if a person were at 50,000 feet or 
above without oxygen equipment. 
Antigravity — a hypothetical effect upon masses, such as a 
rocket vehicle, by which some yet-to-be-discovered 
energy field would cancel or reduce the gravitational 
traction of the earth or other body. 
Aphelion— the point at which a planet or other celestial 
object is farthest from the sun in its orbit about the sun. 
Apogee— the point in an elliptical orbit around earth which 

is farthest from earth. 
Arrester hook— a hook attached to an airplane for engag- 
ing an arresting wire; part of the complete arresting 
Asteroid — one of the many small celestial bodies revolving 
around the sun, most of the orbits being between those 
of Mars and Jupiter. Also called "planetoid", "minor 
Astro — a prefix meaning "star" or "stars" and, by extension, 
sometimes used as the equivalent of "celestiaF, as in 
Astrodynamics — the practical application of celestial 
mechanics, astroballistics, propulsion theory, and allied 
fields to the problem of planning and directing the 
trajectories of space vehicles. 
Astronaut — a person who occupies a space vehicle. 
Specifically one of the test pilots selected to participate 
in Project Mercury, the first U.S. program for manned 
space flight. 
Astronautics — the art, skill, or activity of operating space 
vehicles. In a broader sense, the science of space flight. 
Astronomical Unit— mean distance of the earth from the 
sun, equal to 92,907,000 miles. 

Astronomy— the oldest of the sciences; treats of the celestial 
bodies, their magnitudes, motions, constitution, and 

Astrophysics-the study of the physical and chemical 
nature of celestial bodies and their environs. 

Atmosphere — the envelope of air surrounding the earth; 
also the body of gases surrounding or comprising any 
planet or other celestial body. 

Attitude— the position of an airplane as determined by the 
inclination of its axes to some reference, usually the 
earth or horizon. 

Aurora borealis— a luminous phenomenon usually seen in 
this hemisphere in the northern sky when it does occur. 
It is due to electric discharges from the sun. In the 
southern hemisphere the same phenomenon is known 
as aurora australis. 

Autogiro- a type of rotor plane in which lift is produced 
by revolving airfoils or blades hinged to a vertical shaft 
above the fuselage. Some forward speed, as provided 
by an engine that is fitted with a conventional propeller, 
is necessary for takeoff in contrast to the helicopter, 
which has no conventional propeller. 

Axes of an aircraft— three fixed lines of reference perpen- 
dicular to each other and passing through the center 
of gravity of the airplane: longitudinal, running from 
nose to tail; lateral, parallel to a hne drawn from wing 
tip to wing tip; and vertical, perpendicular to the other 

Azimuth— the initial angle or direction between true North 
and a great circle course. 


Ballistics — the science that deals with the motion, behavior, 
and effects of projectiles, especially bullets, aerial bombs, 
rockets, or the like; the science or art of designing and 
hurling projectiles so as to achieve a desired perform- 

Ballistic trajectory — the trajectory followed by a body be- 
ing acted upon only by gravitational forces and the 
resistance of the medium through which it passes. 

Balloon — (I) a bag, usually spherical, made of silk or 
other light, tough, nonporous material filled with some 
gas which is lighter-than-air, (2) a term describing the 
tendency of an aircraft to float or maintain altitude at 
minimum speed. 

Banking— (bank)— to incline an airplane laterally or roll it 
about its longitudinal axis; the position of an airplane 
when its lateral axis is incfined to the horizontal. 

Aneroid— An instrument indicating atmospheric pressure 
by the action of a partially air-evacuated aneroid cell. 
Mercurial— an instrument indicating atmospheric pres- 
sure in terms of the height in inches of a column of 
mercury supported by it in an air-evacuated glass 
Beaching gear— wheels and struts which can be fastened 
to the hull of a flying boat when at rest in the water, 
permitting the boat to be hauled up onto land. 
Beacon— a light, group of lights or other signalling device, 
indicating a location or direction. 


Beam— a comparatively narrow directional radio signal 
formed by interlocking and blending the A and N 
signals of a radio range station. 

Bearing— the angle from one object to another, generally 
measured clockwise through 360° from a given refer- 

Magnetic— the angle to an object, measured clockwise 
through 360° from the magnetic meridian (i.e.. Mag- 
netic North). (Magnetic bearing equals true bearing 
plus or minus magnetic variation.) 
Relative— the angle to an object from the nose of an air- 
plane (longitudinal axis), measured clockwise. 
True— the angle to an object, measured clockwise 
through 360° from the true geographic meridian 
(i.e.. True North, 0°). 

Bioastronautics— astronautics considered for its effect upon 
animal or plant life. 

Biplane— an airplane having two wings or supporting sur- 
faces, one located above the other. 

Bipropellant — a rocket propellant consisting of two unmix- 
ed or uncombined chemicals (fuel and oxidizer) fed to 
the combustion chamber separately. 

Bird — a colloquial term for a rocket, satellite, or space- 

Compressor— revolving compressor blades pull air into 
the engine, forcing it back through diminishing pas- 
sages to compress it. A modern gas turbine may have 
several hundred blades arranged in rows called stages. 
Turfotne— turbine blades extend into the stream of hot 
gases rushing through the engine. These gases, which 
were ignited in the combustion section, push against 
the turbine blades, causing the turbine shaft to rotate. 

Blimps— a nonrigid dirigible; sometimes also a semirigid 

Blister— a dome made of Plexiglas or some other similar 
substance protruding from the fuselage of the airplane 
providing navigators, observers or gunners with better 

Boat, flying— a type of aircraft in which the fuselage (hull) 
is especially designed, being both strong and water- 
proof, to permit water landing only. 

Booster vehicle— the engine, or engines, on a rocket or 
guided missile that provides the initial thrust to get the 
unit into motion— or into the air. Usually, the booster 
operates for a very short time— a few seconds or minutes 
—and is then burned out or cut off. These engines pro- 
vide a powerful thrust and expend a great amount of 
fuel. The entire section containing the booster is dropped 
to hghten the missile or rocket. The operation is com- 
parable to the use of jet-assisted take-off on conventional 

Bucket— one of the blades or vanes attached to the tur- 
bine wheel in a jet engine or to the wheel of a gyro- 

Bumpiness— an unstable condition of the air often result- 
ing in minor vertical changes in an aircraft's flight path. 
A condition resulting from flight in rough air. 

Burble— a term used to illustrate severe disturbances of 
the streamlined flow around an airfoil. 

Burnout — an act or instance of the end of fuel and oxidizer 
burning in a rocket; the time at which this burnout 

Calibrated Air Speed— (See Airspeed.) 

Camber— the curvature of the upper or lower surface of 
an airfoil with respect to its chord. 


Full— a type of wing constiuction in which the internal 
construction is sufficiently strong to eliminate the 
necessity for external bracing. 
Semi— a type of wing construction in which the internal 
construction is less strongly built, thereby requiring 
external short struts or braces. 

Carburetor — an apparatus on an engine which mixes air 
and fuel in proper proportions to form a highly com- 
bustible mixture. 

Heater— a device installed on a carburetor to prevent 
icing caused by refrigeration due to vaporization of 
the gasoline. 

Capsule— a small, sealed, pressurized cabin with an ac- 
ceptable environment, which contains a man or animal 
for extremely high-altitude flights, orbital space flight, 
or emergency escape. 

Ceiling— the height above ground of the base of a cloud 

Ai>soZu(e— maximum height above sea level that an air- 
plane will reach under its own power. 
Sert>ice— height above sea level beyond which the air- 
plane is unable to climb 100 feet per minute. 

Centrifugal force— a force which tends to force an object 
outward from a center of rotation. 

Centrifuge— a large motor-driven apparatus with a long 
rotating arm at the end of which human and animal 
subjects or equipment can be revolved at various speeds 
to simulate very closely the prolonged accelerations en- 
countered in high-performance aircraft, rockets, and 
manned missiles. 

Centripetal force— a force which tends to force an object 
inward toward a center of rotation. 

Chamber, cannular combustion— a tube, roughly cylindri- 
cal, between the compressor and turbine of a jet engine, 
in which fuel is injected into the airstream and burned. 

Chart— an aeronautical navigation map showing lines of 
latitude and longitude, compass roses, topographical 
detail, prominent land marks and other aids and dangers 
to aerial navigation. 

Check points— a known or designated point or feature, as 
a landmark, beacon, mountain, city, or the like, used as 
a reference in air navigation or for orientation in flying. 


Leri;^/i— the projection of the airfoil on its chord length. 
Line— the reference line of an airfoil by which curva- 
tures are specified. It consists of a shaight line ex- 
tending roughly from the center of the leading edge 
backwards to the trailing edge. 

Cislunar space — space between the earth and the orbit of 
the moon. 

Clearance— the difference in diameters of closely fitting 
parts, such as piston and cylinder or bearings and jour- 

Climate— the natural weather conditions of any region or 
portion of the earth. 

Climb— the action of an airplane when ascending under 



Alto-cumulus— a. fleecy, middle-height cloud formation 
made up of large whitish or grayish cloudlets, often 
grouped in rows. 

Alto-stratus— A middle-height sheet cloud similar to ciiTo 
stratus but thicker and heavier. 

Cirro-ci/mi;/i/4'— small, white, rounded masses of high 
altitude clouds, referred to as mackerel sky. 

Cirro-stratus— uniiorm layer of high altitude cloud, 
formed of ice particles. 

Cirrus— a light, fleecy, filmy high altitude cloud (20,000 
to 40,000 feet) formed of minute ice particles. 

Cumulo-nimbus— a. very turbulent, mountainous mass of 
condensed water vapor from which may fall rain, 
snow, or hail; commonly called a thunderhead. 

Cumulus— d billowy, heaped-up cloud formation usually 
found between 5,000 and 15,000 feet and having a 
flat base. 

Nimbo-stratus—d gray, layer-like type of rain cloud cov- 
ering the entire sky. 

Strata-cumulus— \aige billowy masses of low level, dark 
clouds which during the winter often cover the whole 

Stratus— Rdt layer-like clouds extending horizontally and 
lying at any height between the surface of the earth 
and an altitude of about 15,000 feet. Stratus clouds 
represent stable air conditions with very little verti- 
cal convection and quite usually associated with 
warm fronts. They occasionally occur at low altitudes 
in a warm air mass, in the form of fog. 
Cold front— (See Front.) 

Comet — a luminous member of the solar system composed 
of a head or coma at the center of which a presumably 
solid nucleus is sometimes situated, and often with a 
spectacular gaseous tail extending a great distance from 
the head. 
Communications satellite — a satellite designed to reflect 

or relay radio or other communications waves. 
Card— a card graduated in degrees from 0'^ to 360° 
rigidly mounted to and actuated by the compass 
Correction card— a. small card mounted near the airplane 
compass indicating the amount of deviation found 
on various headings. 
Course— the true course corrected for variation and devi- 
ation but not for wind. 
Heading— the true course corrected for variation, devi- 
ation, and wind. 
Magnetic— an instrument in which shongly magnetized 
needles, affected by the earth's magnetic field, are 
used to determine direction of flight. 
Rose— a. circle, graduated in degrees from 0° to 360°, 
printed on aeronautical charts at convenient intervals 
and used for plotting directions. 
Condenser— a device for storing electrical energy; a 

Configuration — a particular tv'pe of a specific aircraft 
rocket, etc., which differs from others of the same model 
by virtue of the arrangement of its components or by 
the addition or omission of auxiliary equipment as 'long- 
range configuration", "cargo configuration". 
Connecting rod— a rod in an aircraft engine which trans- 
mits the energy exerted by the piston to the crankshaft. 

Contact flying— flight of an aircraft in which its attitude 
and flight path can at all times be determined by visual 
reference to the ground. 
Contour line— a line connecting all points of equal eleva- 
tion above sea level. 
Control, balanced— (surface)— a control surface which ex- 
tends on both sides of the hinge in such a manner that 
the wind force striking the surface aids the pilot in 
moving the controls. 

Cable— any cable in an aircraft which transmits move- 
ment from the control levers to the control surfaces. 
Column— a lever, corresponding to the control stick, hav- 
ing a rotatable wheel mounted at its upper end for 
operating the longitudinal and lateral control surfaces 
of an airplane. 
Stick— the vertical lever by means of which the longi- 
tudinal and lateral control surfaces of an airplane are 
Surface— a movable airfoil designed to be moved by the 
pilot in order to change the attitude of an aircraft. 
Controls— a general term applied to the means provided to 
enable the pilot to control the speed, dii-ection of flight, 
attitude, and power of an aircraft. 
Convection— the upward or downward movement, me- 
chanically or thermally produced, of a limited portion 
of the atmosphere. Convection is essential to the forma- 
tion of many clouds, especially of the cumulus type. 
Convertiplane— an aircraft so built that it can perform, at 
the will of the operator, as any one of two or more 
different types of vehicles, especially an aircraft that 
can be adjusted to fly either as a fixed-wing airplane or 
as a helicopter or autogiro. 
Corona — the faintly luminous outer envelope of the sun. 

Also called "solar corona". 
Cosmonaut— Russian term for their astronaut Major Yuri 

Gagarin, the first man in space. 

Countdown— a time-sequenced step-by-step process for 

final check-out and preparation of a missile for launch. 

Counter rotating— propellers having two sets of blades 

mounted coaxially and revolving in opposite directions. 

Course— the direction over the surface of the earth that 

an aircraft is intended to travel, sometimes referred to 

as intended track. 

Compass— the angle in degrees between North on the 
compass and the desired course of the plane meas- 
ured clockwise through 360°. 
Line— the direction over the surface of the earth that an 
aircraft is intended to travel, sometimes referred to 
as intended track. 
Magnetic— the angle in degrees between Magnetic North 
and the desired course of the plane measured clock- 
wise from Magnetic North through 360°. 
True— the angle in degrees between the nearest geo- 
graphic meridian and the desired course of the plane 
measured clockwise from 0°— True North— through 
Cowling— a removable covering over the engine. 
Crankcase— that part of the aircraft engine which holds 
the bearings for the crankshaft, timing gear, cam shaft, 
etc., and which supports the oil pan and cyhnders. 
Crankshaft— a shaft in an aircraft engine which receives 
its rotation from off-set cranks and to which the pro- 


peller is attached. 

Cultural features— a map-making term referring to works 
of man, that is cities, railroads, highways, airports, etc. 

Cyclone— in meteorology an area of low barometric pres- 
sure called, on weather maps, a low. 

Cylinder— a chamber in an aircraft engine of which the 
upper part serves as the combustion chamber and the 
lower part houses the sliding piston. 

Deep space probes — spacecraft designed for exploring 
space in the vicinity of the moon and beyond. Deep 
space probes with specific missions may be referred to 
as "lunar probe", "Mars probe", "solar probe", etc. 

Degree— a 360th part of the circumtereuce of a circle, or 
a 9()th part of a right angle. 

De-icer boots— a rubber strip on the leading edge of an 
airfoil actuated pneumatically to break ice which has 
formed. Also a rubber strip on the base and the leading 
edge of a propeller blade over which alcohol is sprayed 
to prevent the formation of ice. 

Depression— (See Cyclone.) 

Destruct — the deliberate action of destroying a rocket 
vehicle after it has been launched, but before it has 
completed its course. 


Card— the card usually placed near a compass giving the 
deviation correction for converting magnetic head- 
ings to compass headings. 
Errors— the error of a magnetic compass caused by mag- 
netic influences in the structure and the equipment 
of an aircraft. 

Dew— moisture condensed on the ground as a result of a 
chilling of the earth's surfaces, i.e., the layer of air rest- 
ing on the earth's surface. 

Dew point— the temperature at which, under ordinary con- 
ditions, condensation begins in a cooling mass of au'. 

Diaphragm, nozzle — in a jet engine, a row of stator blades 
immediately preceding the turbine wheel, which has the 
dual purpose of increasing gas velocity and of directing 
it upon the turbine blades at the proper angle. 

Dihedral— ( See Angle.) 

Discontinuity— the term applied in a special sense by 
meteorologists to a zone within which there is a com- 
paratively rapid change of meteorological elements, as 
in a warm or cold front. 

Distributor— an apparatus for directing the secondary cur- 
rent from the induction coil to the various spark plugs 
of a multicylinder engine. 

Dive— a steep descent, with or without power, in which 
the airspeed is greater than the maximum speed in 
horizontal flight. 

Docking — the process of bringing two spacecraft together 
while in space. 

Dope — a compound, made of cellulose-nitrate or cellulose- 
acetate-butyrate, used on fabric surfaces of airplanes, 
making such surfaces taut and weather resistant. 

Doppler navigator— navigation equipment contained in an 
aircraft which gives accurate position information but 
which operates independently of ground based radio 

Doppler shift — the change in frequency with which energy 
reaches a receiver when the source of radiation or a 

reflector of the radiation and the receiver are in motion 
relative to each other. The Doppler shift is used in 
many tracking and navigation systems. 

Double drift— a wind force and direction-finding method 
in which the drift angle is observed on each of two 
successive headings at a known airspeed. 

Downwash— the air deflected in a direction perpendicular 
to the direction of motion of the airfoil. 

Drag— the component of the total air force on a body 
parallel to relative wind and opposite to thrust. 
Induced— that component of drag which is induced bv 

Parasite— that component of drag not including the in- 
duced drag of the wings. 
Pro^— the result of subtracting the induced drag from 
the total wing drag. 

Drizzle— precipitation originating from stratus clouds con- 
sisting of numerous tiny droplets. 

Duralumin— a very strong copper, aluminum, and manga- 
nese alloy which may or may not include magnesium, 
widely used in aircraft construction. 

Ecliptic — the intersection of the plane of the earth's orbit 
with the celestial sphere. 

Elevator— a movable auxiliary airfoil, usually hinged to 
the horizontal stabilizer and used to control the air- 
plane's angle of attack. 

Empennage— the tail assembly of the fuselage including 
the fixed and movable control surfaces, that is, the fin, 
rudder, stabilizer and elevator. 

Equi-signal zone— a zone of equal signal strength of the 
"on course" signal of a radio range, where a steady tone 
is heard as the result of the reception of the energy from 
the two antenna systems being received with equal 

Escape velocity— minimum velocity which will enable an 
object to escape from the surface of the earth without 
further propulsion. The escape velocity of the earth is 
just over seven miles per second, or 25,000 mph. 

Estimated time of arrival (ETA)— the estimated time at 
which the pilot of an aircraft expects to aiTive at a 
given destination as based on his calculations from 
known factors. 

Exhaust port— the opening from which the burned gases 
escape from the cylinder after their combustion. 

Exosphere- outermost region of the earth's atmosphere, 
where atoms and molecules move in dynamic orbits 
under the action of the gravitational field. 

Fading— diminishing of signal stiength due to increasing 

distance from a radio station or because of other radio 

Fairing— a drag-reducing auxiliary part of an aircraft, 

usually covering a part that would otherwise create a 

much greater parasite drag. 
Feathered— a propeller whose blades' leading edges are 

turned parallel to the line of flight, thereby reducing 

drag and preventing windmilling in the case of engine 

Fin— an approximately vertical fixed or adjustable airfoil 

attached to the tail of an airplane to provide directional 


Fix— a definite geographic position ot an aircraft deter- 
mined by the intersection of two or more bearings or 

hnes of position. 
Fixed satellite — an earth satellite that orbits from west to 

east at such a speed as to remain constantly over a 

given place on the earth's equator. 
Flaps— hinged or pivoted auxiliary airfoils forming part of 

the trailing edge of the wing and used to increase lift 

at reduced airspeeds. 
Flight path— the flight path of the center of gravity of an 

aircraft with reference to the earth. 
Floats— an enclosed water-tight structure attached to an 

aircraft to give it buoyancy and stability when in con- 
tact with water. 
Float chamber— a chamber in a carburetor which contains 

the float and the proper supply of gasoline to feed 

the spray nozzle. 
Fog— a cloud at the earth's surface. 
Four cycle— (engine)— a four-stroke-cycle engine. 
Free fall — the fall or drop of a body, such as a rocket, 

not guided, not under thrust, and not retarded by a 

parachute or other breaking device. Weightlessness. 
Front— a surface of discontinuity between two overlapping 

air masses possessing different densities; also the 

boundary between two different air masses. 

CoW— the border at the forward edge of an advancing 
cold air mass displacing warmer air in its path. 

Stationary— A front along which neither air mass is dis- 
placing the other to any significant degree. 

Warm— the line of discontinuity found at the forward 

edge of an advancing current of relatively warm air 

which is over-running a retreating mass of colder air. 

Frost- atmospheric moisture deposited upon objects in 

the form of ice crystals. 
Fuel pump— a small engine driven pump which makes 

gasoline available to the carburetor inlet from the fuel 

tank; used in cases where the fuel tanks are below the 

carburetor level. 
Fuel system— all parts of an airplane having to do with 

the consumption of gasoline. 
Fuselage— the approximately streamlined body to which 

the wings and tail unit of an airplane are attached. 

Galaxy— the group of several billion suns, star clusters, 
etc. Most recognizable is our own galaxy, the Milky 
Way. Also refers to any groups of stars forming in- 
dependent units. 

Gantry— crane-type structure, with plattonns on ditterent 
levels, used to erect, assemble, and service huge rockets 
or missiles; may be placed directly over the launching 
site and rolled away just before firing. 

Gap — distance between the wings of a biplane as measured 
from the chord line of the upper wing to the chord line 
of the lower wing. 

Garbage — miscellaneous objects in orbit, usually material 
ejected or broken away from a launch vehicle or 

Gear pump— a type of oil pump which derives its pump- 
ing action from a set of meshed gears, the teeth of 
which are in close clearance to the inside wall of the 
pump housing. 

Generator— machines used to transform mechanical energy 
into electric energy. 

Geocentric— relating to or measured from the center of the 
earth; having, or relating to, the earth as a center. 

Geodetic — pertaining to geodesy, the science which deals 
with the size and shape of the earth. 

Geographic poles— the north and south poles through 
which pass all geographic meridians and around which 
the earth rotates. 

Geophysics— the physics of the earth, or the science treat- 
ing of the agencies which modify the earth. 

Glaze— a U. S. Weather Bureau term for a smooth coating 
of ice on objects due to the freezing of rain. 

Glide— a descent at a normal angle of attack with little 
or no power. 

G-load— the force exerted on an object by gravity or by 
an acceleration. One G is the measure of the gravita- 
tional pull exerted on a body by earth at approximately 
sea level. 

Gnomonic— a method of chart projection on which straight 
lines represent great circle courses. 

Grain— a single piece of powder charge regardless of size 
or shape used in a rocket. 

Granular snow— a form of precipitation consisting of small 
nontransparent grains of snow. 

Gravity— the force which tends to draw all bodies toward 
the center of the earth. 

Great circle— an imaginary circle on the earth's surface 
which is made by passing a plane through the center 
of the earth (e.g., any meridian or the Equator). 
Bearing— the direction from one place to another which 
follows a great circle passing through both places. 

Greenwich meridian— the meiidian passing through the 
location of the principal British observatory near Lon- 
don and from which longitude is reckoned east or west. 

Ground loop— an uncontrollable violent turn of an air- 
plane while taxiing or during the landing or takeoff run. 

Ground speed— the actual speed of the airplane over the 

Guidance — the process of directing the movements of an 
aeronautical vehicle or space vehicle, with particular ref- 
erence to the selection of a flight path or trajectory. 
Beam Rider— d system for guiding missiles in wfiich the 
guided missile rides along a beam, usually a radar 
beam, to its target. 
Command— a tyV^ of electronic guidance of guided 
missiles or other guided aircraft wherein signals or 
pulses sent out by an operator cause the guided ob- 
ject to fly a directed path. 
Homing— the guidance given a guided missile or the like 

by built-in homing devices. 
Preset— a type of guidance for guided aircraft rockets 
or other guided missiles in which the path of the 
missile is determined by controls set before launching. 

Gust— a sudden brief increase in the force of the wind. 

Hail— irregular lumps or balls ol ice, often of consider- 
able size and having a complex structure, falling almost 
exclusively in thunderstorms. 

Halo— a name for a group of optical phenomena caused 
by ice crystals in the atmosphere. 


Haze— a lack of transparency in the atmosphere caused 
by the presence of dust or of salt particles left by evap- 
orated ocean spray. At a certain distance, depending on 
the density of the haze, all details of landscape and 
color disappear. 

Compass— the angle between north as indicated on the 
airplane compass and the direction in which the ship 
is headed. 
Magnetic— the angle between magnetic north and the 

direction in which the ship is pointed. 
True— the angle between True North and the direction 
in which the airplane is pointed. 

Helicopter— a type of rotor plane whose support in the 
air is derived from airfoils mechanically rotated about 
an approximately vertical axis. It is capable of vertical 
flight or hovering at a given altitude. 

Heliocentric— measured from the center of the sun; related 
to, or having the sun as a center. 

High— an area of high barometric pressure. 

Horn— a short lever which moves a control surface in re- 
sponse to the movement of the control wires. 

Horizon— the line where the earth and sky seem to meet. 

Hp (horse power)- unit by which rate of work is measiued 
—one horsepower is the power necessary to lift 550 
pounds one foot in one second. 

Hull— the water-tight fuselage or body of a flying boat, 
which supplies the buoyancy necessary for operation 
from the water. 

Humidity— the percentage of invisible moisture particles 
in a given parcel of air. 

Relative— the ratio of the actual amount of vapor pres- 
ent in a given parcel of air to its saturation point 
at the same temperature. 

Hydraulic— any force exerted by liquid pressure. 

Hypersonic— velocities of five or more times the speed of 

Hypoxia— oxygen deficiency in the blood in high-altitude 
flight, impairing phvsical faculties. Occurs at about 
20,000 feet. 


ICBM— a ballistic missile with sufficient range to strike at 
strategic targets from one continent to another. ICBM 
minimum range is approximately 5,000 miles. 

Ice needles— thin crystals or shafts of ice so light that they 
seem to be suspended in the air. 

Ice rain- (1) a rain that causes a deposit of glaze, (2) 
falhng pellets of clear ice, called sleet by the U.S. 
Weather Bureau. 

IGY— International Geophysical Year. 

Impact pressure— the pressure imposed by a moving object 
striking a relatively motionless body. 

Incidence— (See Angle). 

Inconel-x— a registered trade-name of The International 
Nickel Company, Inc. The name "Inconel" is applied 
to a nickel chromium-iron alloy. It contains approxi- 
mately 80% nickel, 14% chromium and 6% iron. It has 
physical properties similar to stainless steel and is used 
in the X-15. 

Indicated airspeed— ( See Airspeed.) 

Inertia— the tendency of a body to remain in a static 
state, state of rest, or a state of motion, until it is acted 

upon by a moving force. 

Inertial force— the force produced by the reaction of a 
body to an accelerating force, equal in magnitude and 
opposite in direction to the accelerating force. Inertial 
force endures only as long as the accelerating force 

Inertial guidance— a pre-set guidance system with a 
course-and-distance measuring mechanism composed of 
three accelerometers and a computer. Primarily em- 
ployed as a navigation and guidance device in missiles, 
space craft, and high altitude performance aircraft. 

Infrared— pertaining to or designating those rays lying just 
beyond the red end of the visible spectrum, such as are 
emitted by a hot nonincandescent body. Their wave 
lengths are longer than those of visible light and 
shorter than those of radio waves. 

In-line engine— an internal-combustion, reciprocating en- 
gine in which the cylinders are arranged in one or 
more straight rows. 

Insolation— solar radiation as received by the earth or other 

Instrument flight— flight which is controlled solely by 
reference to instruments, i.e., without any reference to 
landmarks. Involves maintainance of definite altitudes 
and navigation by dead reckoning and radio. 

Intake valve— a valve in an aircraft engine which is auto- 
matically opened on the intake stroke of the piston, for 
the proper length of time, to permit the charging of the 
cylinder with the fuel mixture. 

Internal combustion— a term used to define an engine that 
receives driving force by the burning of fuel in its 

Ion — an atom or molecularly bound group of atoms having 
an electric charge. Sometimes also a free electron or 
other charged subatomic particle. 

Ionosphere— region of the earth's atmosphere extending 
fifty to 500 miles above the earth, merging into the 
exosphere above. 

IRBM-a ballistic missile with a range of 200 to 1,500 

Isobar— a line on a weather chart drawn through places 
or points having the same barometric pressure. 

Isogenic lines— imaginary lines on the surface of the earth 
at all points on which the magnetic variation is the same. 
The Agonic line is the line of no variation. 

Jet, Pulse— a kind of jet engine of the athodyd group, hav- 
ing neither compressor nor tuibine, but equipped with 
vanes in the front end which open and shut, taking in 
air, to create power, in rapid periodic bursts rather than 
by continuous inhaling. 

Ram— a jet engine consisting essentially of a tube open 
at both ends in which fuel is burned continuously to 
create a jet thrust, and having neither a compressor 
nor turbine. 
Turbo — a jet engine which obtains thrust from the in- 
crease in air velocity as it passes through the com- 
pressor, where its density is increased; the combustion 
section, where it is mixed with fuel and burned to ob- 
tain increased pressure; and the turbine and exhaust 
cone, where its velocity is further increased as its 


pressure drops. The turbine's single function is to 
drive the compressor to increase air pressure before 
it enters the combustion chambers. 
Turboprop — a variation of the turbojet in which the tur- 
bine absorbs most of the energy of the flowing gases 
and transmits it through a shaft and reduction gears 
to a propeller. 

Knot— a measure of speed. One knot being a speed of one 
nautical mile per hour. 

Lambert projection— a method of projecting a portion of 
the curved surface of the earth on a flat chart with a 
minimum amount of distortion. 
Landing— the act of terminating flight in which the air- 
craft is made to descend, lose flying speed, establish 
contact with the ground or water and finally come to 
Area— that portion of the field available for takeoft's and 

Geor— the understructure which supports the weight of 
an aircraft when in contact with the land or water 
and which usually contains a mechanism for reducing 
the shock of landing. Also called under carriage. 
Some landing gear is retractable or able to be drawn 
up into the wings or body of an airplane in flight to 
reduce parasitic drag. 
Pancake— a landing in which the leveling-off process is 
carried out several feet above the ground, as a result 
of which the airplane settles rapidly on a steep flight 
path in normal attitude. 
Three point— the act of contacting the ground simul- 
taneously with the wheels and tail wheel or skid of 
the aircraft. 
Lapse rate— the rate temperature decreases in relation to 

altitude decrease. 
Laser- (from Zight amplification by stimulated emission 
of radiation) a device for producing light by emission 
of energy stored in a molecular or atomic system when 
stimulated by an input signal. 
Lateral axis— (See Axis). 

Latitude— the angular measurement north or south of the 
equator of any point on the earth measured in degrees, 
minutes, and seconds of arc from to 90 degrees. 
Launch— send forth a rocket or missile from its launcher 

under its own power. 
Launching pad— launch stand upon which the missile will 
stand when ready for liftoff, plus the service tower that 
can be moved out of the way on tracks, the flame 
bucket, the ground-support equipment located nearby 
to control the countdown sequence, and the protective 
building or trailer housing the equipment. 
Launch vehicle — any device which propels and guides a 
spacecraft into orbit about the earth or into a trajectory 
to another celestial body. Often called "booster". 

Leading edge— the foremost edge of an airfoil or propeller 

Level-ofF— to make the flight path of an airplane horizon- 
tal after a climb, glide, or dive. 

Lift— the nearly vertical reaction resulting from the pas- 
sage of an airfoil through the air. Lift always acts 
approximately perpendicular to the relative wind. 

Liftoff — the action of a rocket vehicle as it separates from 
its launch pad in a vertical ascent. A liftoff is applicable 
only to vertical ascent; a takeoff is applicable to ascent 
at any angle. 

Lightning— a disruptive electrical discharge in the atmos- 
phere or the luminous phenomena attending such a 

Light-year — the distance light travels in one year at 186,- 
000 miles per second. 

Line squall— a more or less continuous line of squalls and 
thunderstorms marking the position of an advancing 
cold front. 

Link Trainer and Link Simulator— a synthetic replica of 
an aircraft cockpit containing a complete panel of con- 
trols, radio aids, and computer-actuated flight and en- 
gine instruments. Used for training pilots and crews in 
instrument flying, emergency procedures, and, in some 
instances, complete tactical missions. 

Liquid-propellant rocket engine — a rocket engine fueled 
with a propellant or propellants in liquid form. Rocket 
engines of this kind vary somewhat in complexity, but 
they consist essentially of one or more combustion 
chambers together with the necessary pipes, valves, 
pumps, injectors, etc. 

Load— the force or pressure exerted upon an object under 
static or dynamic conditions, either by virtue of its own 
weight or by some imposed object or force. 
Factor— {in flight maneuvers) the ratio of the aero- 
dynamic load imposed upon the lifting surfaces in a 
specified maneuver to that imposed in normal level 
Full— empty weight plus useful load. Also called gross 

Pay— that part of the useful load from which revenue is 

Useful— the crew and passengers, oil and fuel, ballast, 
other than emergency, ordnance or portable equip- 


Of aircraft— placing the useful load in an airplane so as 
not to disturb the normal level position of the airplane 
in flight. 
Power— the result of dividing the gross weight of the 
airplane by the rated horsepower of the engine com- 
puted for air of standard density. 
Wing— obtained by dividing the gross weight of the 
airplane by its wing area. 

Log— a written record, either computed or observed, 
of navigational data; a record of a pilot's flying time; an 
operational record of an aircraft or its engine (s). 

Longeron— any one of the principle longitudinal members 
of the internal construction of an airplane fuselage, usu- 
ally continuous across a number of points of support. 

Longitude— the angular measuiement of any point on the 
earth's surface east or west of the Greenwich meridian, 
measured in degrees, minutes, and seconds of arc from 
to 180 degrees along the parallel of latitude which 
passes through that point. 

Longitudinal axis— (See Axis.) 

Low— an area of low barometric pressure, with its attend- 
ant system of winds. Usually called a barometric de- 

pression or cyclone. 
LOX— liquid oxygen used as an oxidizer. 
Lubber line— a clearly defined, fixed index or reterence 

line on an aircraft instrument. 
Lunar— of or pertaining to the moon. 

Mach number— a number expressing the ratio of the speed 
of a moving body or of air to the speed of sound, with 
Mach 1.0 equal to the speed of sound. 

Mackerel sky— a portion of cirro-cumulus or alto-cumulus 
covered sky. 

Magnetic north— the north of the earth's magnetic field, 
situated at about Lat. 71° N., Long. 96° W., more than 
1,000 miles from the geographic north pole. 

Magneto — a device for generating electricity, usually of 
high voltage, which is delivered to the spark plugs, in 
the proper order and at the proper time, by the dis- 

Map— a flat surface representation of a portion of the 
earth's curved surface, drawn to some convenient scale, 
and usually dealing with or showing more land than 
water. The unit of linear measurement of surface dis- 
tance used in map making and map reading is the 
statute mile (5,280 feet). 

Maser — an amplifier utilizing the principle of microwave 
amplification by stimulated emission of radiation. 

Mercator— the chart projection on which latitude and 
longitude lines are represented as straight lines inter- 
secting at right angles. On this projection rhumb lines 
(or lines of constant course) are represented by straight 
lines and great circles by curved lines. 

Meridian— a great circle on the earth's surface passing 
through the North and South Poles. 

Meteor — in particular, the light phenomenon which re- 
sults from the entry into the earth's atmosphere of a 
solid particle from space; more generally, any physical 
object or phenomenon associated with such an event. 

Meteorite — a meteoroid which has reached the surface of 
the earth without being completely vaporized. 

Meteoroid — a solid object moving in interplanetary space, 
of a size considerably smaller than an asteroid and 
considerably larger than an atom or molecule. 

Meteorology— the scientific study of the atmosphere. 

Mid-meridian— a meridian passing through the halfway 
point between two places on the earth's surface. 


Nautical— the unit of 6,080.2 feet tor measuring dis- 
tances. For practical purposes one minute of latitude 
may be considered equal to a nautical mile. 
Statute— the unit of 5,280 feet for measuring distances. 

Millibar— a unit of pressure used in reporting weight of 
atmosphere on weather charts. One inch of mercury is 
equal to approximately 33.8 millibars. The standard 
atmospheric pressure of 29.92 inches of mercury equals 
approximately 1,013 millibars. 

Minute of arc— 60 minutes of arc are equal to one degree. 

Missile, ballistic— any missile guided especially in the up- 
ward part of its trajectory, but becoming a free-falling 
body in the latter stages of its flight. 

GuiJed— controlled or controllable as to direction by 
present mechanisms, radio commands, or built-in self- 
reacting devices. 

Mist— a thin fog in which the horizontal visibility is 
greater than one kilometer or approximately 1,100 yards. 

Module — a self-containued unit of a launch vehicle or 
spacecraft which serves as a building block for the 
overall structure. The module is usually designated by 
its primary function as "command module" , "lunar land- 
ing module". 

Monoplane— an airplane having but one wing or support- 
ing surface. 

Monopropellant— a rocket propellant in which the fuel and 
oxidizer are premixed ready for immediate use. 

MPH— the standard abbreviation for "miles per hour." 

Multiple courses— a number of narrow equi-signal zones 
resulting from the breaking up of a radio range course 
by mountainous topography or other causes. 

Multipropellant— a propellant that consists of two or more 
liquid ingredients each separated from the others until 
introduced into the combustion chamber. 

Multistage rocket — a vehicle having two or more rocket 
units, each unit firing after the one in back of it has 
exhausted its propellant. Normally, each unit, or stage, 
is jettisoned after completing its firing. Also called a 
"multiple-stage rocket" or, infrequently, a "step rocket". 


NACA— National Advisory Committee for Aeronautics. 

Nacelle— an enclosed shelter for personnel or for a power 
plant in an airplane, usually shorter than the fuselage 
and without a tail unit. 

NASA— National Aeronautics and Space Administration. 

Nautical mile (NM)— a measure of distance equal to 6,- 
076.103 feet or approximately 1.15 miles. 


Celestial— the method of obtaining a fix by reference to 
the altitude or angular height above the horizon of 
celestial bodies at a given instant. 
Dead reckoning— the fixing of position using known 
directions, ground speed, and elapsed time from a 
given point. 
Pilotage (Map Reading Navigation)— directing an air- 
plane with respect to visible landmarks. 
Radio— the fixing of position by means of various radio 
aids, i.e., radio ranges, radio direction finding equip- 
ment, etc. 

Nephoscope— an instrument for measuring the movement 
of clouds. 

Non-rigid dirigible— a lighter-than-air craft having a gas 
bag, envelope, or skin that is not supported by any 
framework nor reinforced by stittening. It maintains 
its shape by internal pressure of the gas with which 
it is filled. 

Nosecone — assembly at the upper end of a ballistic missile 
from which it is separated after the end of propelled 
flight. The nosecone may contain an atomic bomb with 
an arming and fuzing system, and a means of deceler- 
ating the body as it speeds down into the atmosphere. 

Nozzle diaphragm — (see Diaphragm, nozzle.) 

Nozzle, filled— a duct through which a liquid or gas is 
directed, designed to increase the velocity of the liquid 
or gas; specifically, a jet nozzle for a jet engine or 


Occluded front— a line along which a waim or cold front 
overtakes a slow moving cold or warm front, forcing 
aloft a parcel of the warmer air. 
Oil pump— gear, vane, or plunger type of pump used to 
lift oil from the sump to the upper level tank and to 
provide pressure for the circulation of oil in an engine. 
Oleo struts— a special kind of shock-absorbing strut used 
in certain landing gear, depending essentially on a 
hydraulic action. The oleo strut is a telescoping strut 
consisting of a hollow piston, which upon compression, 
forces a fluid through a small orifice in the piston, 
causing the piston to travel slowly so as to cushion the 
shock. Most types of oleo struts employ, in addition to 
the hydraulic device, compressed air, coil springs, or 
Orbit— path in which a celestial body moves about the 
center of gravity of the system to which it belongs; 
every orbit is basically in the shape of a conic section 
with the center of gravity at one focus. 
Orbital speed— velocity needed to keep a body moving 
in a closed orbit around a sun, planet, or satellite. May 
be circular velocity or elliptical velocity and can vary 
over wide limits depending on the distance from the 
attracting force center and upon the magnitude of the 
attracting force; orbital velocity of the Earth is 18,000 
Orbital velocity— speed of body following closed or open 
orbit, most commonly applied to elliptical or near- 
circular orbits. 
Omithopter— an as yet unsuccessful type of aircraft 
theoretically achieving its chief support and propulsion 
from the bird-Hke flapping of its wings. 
Over-the-top flying— flight of an aircraft above an overcast. 
Overshoot— to fly beyond a designated mark or area, such 
as a landing field, while attempting to land. 

Panel— a section of airplane wing separately constructed 
and fitted to the rest of the wing. 

Paraglider — a flexible-winged, kite-like vehicle designed 
for use in a recovery system for launch vehicles or as 
a reentry vehicle. 

Parallel (of latitude)— a circle on the earth's surface 
parallel to the plane of the equator at all points. 

Payload — originally, the revenue-producing portion of an 
aircraft's load, e.g., passengers, cargo, mail, etc., by 
extension, that which an aircraft, rocket, or the like 
carries over and above what is necessary for the opera- 
tion of the vehicle during its flight. 

Perigee— the point in an elliptical orbit which is nearest 

Perihelion— the point in an elliptical orbit around the sun 
which is nearest the sun. 

Photon engine — a projected type of reaction engine in 
which thrust would be obtained from a stream of elec- 
tromagnetic radiation. 

Piston— a closely fitting, plunger shaped pait of an engine 
which slides within the cyhnder. 

Pin— anchors the piston to the connecting rod assembly. 
Ring— an iron ring fitted into a groove in the piston 

head, the purpose of which is to provide a pressure 
seal between the piston and the cylinder wall, thus 
keeping oil from the combustion chamber and in- 
creasing the head compression characteristics. Also 
used as a heat-conducting medium from the piston 
head to the cylinder wall. 
Pitch— an airplane's movement about its lateral axis. 
Adjustable— a. propeller, the blades of which are 
mounted to the hub in such a manner that the pitch 
may be changed only while the propeller is on the 
Constant speed— a. propeller, the blades of which are 
attached to a pitch-changing mechanism that auto- 
matically keeps them at the optimum pitch during 
various flight conditions. 
Controllable— SI propeller, the blades of which are so 
mounted that the pilot may change the pitch at his 
discretion while the propeller is rotating. 
Fixed— a propeller whose pitch cannot be changed. 
Pusher— a propeller so mounted as to push the airplane 
through the air; a propeller mounted aft of its engine. 
Reversible— a propeller that may be turned to reverse 
pitch so as to give reverse thrust. Used to slow an 
aircraft in flight or during the roll after landing. 
Tractor— a propeller that pulls. 
Planet — a celestial body of the solar system, revolving 
around the sun in a nearly circular orbit, or a similar 
body revolving around a star. 
Planetarium— a room or building containing a model or 
representation of the planetary system, especially one 
using projectors to display the movement of celestial 
bodies on a hemispherical ceiling. 
Plot— accurately marking the position and/or course of 

an aircraft or ship on a navigational chart. 
Precipitation— any moisture reaching the earth's surface, 

such as rain, snow, hail, or dew, etc. 
Pressurized — containing air, or other gas, at a pressure that 

is higher than the pressure outside the container. 
Prime meridian— a meridian from which longitude is 
measured. In English-speaking countries and in many 
other countries, the Greenwich meridian is used as the 
prime meridian. 
Projection— any of various methods for representing the 
surface of the earth or the celestial sphere upon a plane 
Protractor— an instrument for laying down and measuring 

angles on paper, used in drawing and plotting. 
Psi— the standard abbreviation for "pounds per square 

Pylon— a rigid structure that protrudes from a wing, fuse- 
lage, or other surface of an aircraft to support a float, 
engine, drop tank, or the like. 

Quadrant— one of the four signal zones, which are 90° 
apart, identified by either the "N" or the "A" signal 
surrounding a Radio Range Station. 

Radial— (engine) an aircraft engine with one or more 
stationary rows of cylinders arranged radially around a 
common crankshaft. (More in AF diet.) 

Radials— any one of a number of lines of position radi- 
ating from an azimuthal radio-navigation facility, e.g., 
VHF omnidirectional radio range, identified in terms 
of the bearing of all points along that line from the 
Radiation— the emission from a body (per unit time per 
unit surface area), of an amount of energy which de- 
pends partly on the nature of the body but to a larger 
extent upon the temperature. 
Radiation fog— fog resulting from the radiation coohng of 
air near the surface of the ground on calm, clear nights. 

Astronomy — the study of celestial objects through ob- 
servation of radiofrequency waves emitted or re- 
flected by these objects. 
Compass— d radio receiver using a fixed or rotating loop 
antenna and a visual indicator, chiefly for "homing" 
of a flight directly toward or away from a radio 
Direction finder— a radio receiver using a manually 
rotatable loop antenna for the purpose of determin- 
ing the direction to or from the transmitting station. 
Detection is made aurally (through the ear) and/or 
visually (by reference to an instrument). 
Automatic (ADFj— similar to the ordinary radio direc- 
tion finder, except that the rotation of the loop is 
automatic and the indicator needle continuously 
indicates the bearing of the station. 
Telescope — a device for receiving, amplifying, and meas- 
uring the intensity of radio waves originating outside 
the earth's atmosphere. 
Radius of action- the distance, determined by fuel capac- 
ity and wind conditions, that an aircraft can safely fly 
in a given direction before returning to its base, with- 
out running out of fuel. 
Reentry— entry of a balhstic missile, nose cone, space 
weapon, or bomb from a satelUte bomber into the at- 
mosphere. The reentry point is the portion of the 
terminal trajectory where thermal heating becomes 
Relief— unequal elevations of the earth's surface noted on 

charts by gradient tinting and by contour lines. 
Retrorocket— a rocket fitted on or in a vehicle that dis- 
charges counter to the direction of flight, used to retard 
forward motion. 
Rhumb line— a line on a chart or the surface of the earth 

that cuts all meridians at a constant angle. 
Rib— a structural member of an aircraft wing which gives 
the wing its proper airfoil shape and which supports 
the wing covering. 
Rigid— a dirigible having several gas bags or cells in- 
closed in an envelope supported by an interior frame- 
work. Distinguished especially from nonrigid and semi- 
rigid airships. 
Rocket — a reaction engine which derives its thrust by ex- 
peUing a mass at high velocity through its open end. It 
is distinguished from a jet in that it is entirely independ- 
ent of the atmosphere. 

Ion— a type of engine in which the thrust to propel the 
missile or spacecraft is obtained from a stream of 
ionized atomic particles, generated by atomic fusion, 
fission, or solar energy. 
Nuclear— a rocket engine in which the hot exhaust gases 
necessary to provide needed thrust will be developed 

by passing a liquid through a fission reactor. 
Photon— a type of rocket or missile engine in which the 

thrust is derived from harnessing a stream of light 

Plasma— ii rocket engine in which the propellant would 

be heated by discharging a powerful electrical charge 

through the propellant. 
Roll— angular motion about the longitudinal axis accom- 
plished by operating the ailerons. 
RPM— the standard abbreviation tor "revolutions per 

minute. " 
Rudder— a hinged or movable auxiliary airfoil on an air- 
craft, the function of which is to initiate a yawing or 
swinging motion on the aircraft. 
Pedal— the foot pedals by means of which the controls 

leading to the rudder are operated. 

Satellite— an attendant body that revolves around another 

Saturation— the condition that exists in the atmosphere 
when the water vapor present is equal to the maximum 
amount of vapor that the air can hold at the prevail- 
ing temperature. 

Selenocentric — relating to the center of the moon; referring 
to the moon as a center. 

Selenographic — of or pertaining to the physical geography 
of the moon, specifically, referring to positions on the 
moon measured in latitude from the moon's equator 
and in longitude from a reference meridian. 

Semi-rigid— a dirigible having its main envelope reinforced 
by some means other than a completely rigid frame- 

Sextant— an instrument used in celestial navigation tor 
deteiTnining the altitude or angle of a celestial body 
above the horizon. 

Shock cords— a cord that absorbs shock, especially one that 
consists of a bundle of rubber strands that permits 

Shower— a fall of rain, snow, sleet, or hail, of short dura- 
tion but often of considerable intensity, falling from 
isolated clouds separated from one another by clear 

Sideslip— motion of an aircraft in a direction downward 
and parallel to an inclined lateral axis. In a turn it is 
the opposite of skidding. Also used to lose altitude 
and airspeed in short landing. 

Skid— sliding sideways away from the center of curvature 
when turning. It is caused by using excessive rudder 

Skin— the covering of an airplane— either metal, fabric 
or plywood. 

Sleet— frozen or partly frozen rain; frozen raindrops in the 
form of clear ice. 

Slipstream— the current of air driven astern by a propeller. 

Slots— a high hft device incorporated in the leading edge 
of an aircraft wing, the primary purpose of which is 
to improve the airflow about the wing at high angles 
of attack. 

Snow— precipitation in the foim of small ice crystals, 
falling either separately or in loosely coherent clusters 

Soar- the art of flying without engine power for prolonged 


periods of time by taking advantage of ascending 
currents of air. 
Soft landing— a landing on the moon or other spatial body 
at such slow speed as to avoid a crash or destruction 
of the landing vehicle. Soft landings on the moon are 
anticipated by use of retrorockets for slow-down of the 
landing vehicle; soft landing on Mars may be accom- 
plished by partial use of the Martian atmosphere. 
Solar— of or pertaining to the sun. 

Solar cell— an electronic device similar to a junction diode, 
in which photons of energy (radiant energy) from the 
sun cause an electron flow across a junction. 
Solid propellant — specifically, a rocket propellant in solid 
form, usually containing both fuel and oxidizer com- 
bined or mixed and formed into a monolithic grain. 
Sonic boom— a sonic boom sounds much like thunder. 
Sonic booms are caused by aircraft flying faster than 
sound. In supersonic flight, an aircraft will cause shock 
waves of compressed air to form. These air waves move 
to the ground and are heard as sonic booms. 
Sonic speed — the speed of sound; by extension the speed 

of a body traveling at Mach 1. 

Cis7(inar— space around the earth beyond the outermost 
reaches of the terrestrial atmosphere and within the 
orbit of the moon. 
I ntergalactic—thdt part of space conceived as having its 
lower limit at the upper limit of interstellar space, 
and extending to the Hmits of space. 
Interplanetary— thdt part of space conceived, fiom the 
standpoint of the earth, to have its lower limit at the 
upper limit of translunar space, and extending be- 
yond the limits of the solar system, some several bil- 
lion miles. (This term is one of distance from earth, 
not one of planetary influence.) 
Interstellar— that part of space conceived, from the 
standpoint of the earth, to have its lower limit at the 
upper limit of interplanetary space, and extending to 
the lower limits of intergalactic space. (From the 
standpoint of a detached observer, it is that part of 
space within the Galaxy.) 
Tra/w/unar— interplanetary space beyond the orbit of 
the moon. 
Spacecraft— a vehicle designed to fly in space. 
Spacesuit— hermetically sealed enclosure for an individual, 
supplying him with a respirable atmosphere, suitable 
temperature, and permitting him mobility. 
Space vehicle— an artificial body operating in outer space. 
May be a pilotless, instrumented vehicle, or a manned 
space vehicle. 
Span— the maximum length of an airfoil from wing tip 

to wing tip measured parallel to the lateral axis. 
Spark plug— in an internal combustion engine, a part fitting 
into the cylinder head, carrying two electrodes separated 
by an air gap across which the current from the ignition 
system discharges thereby forming the spark for com- 

Air— the speed of an airplane through the air. 

Constant— a propeller, the blades of which are attached 

to a pitch-changing mechanism that automatically 

keeps them at the optimum pitch under various flight 


Ground— the actual speed of the airplane over the 

ground, i.e., airspeed plus or minus wind velocity. 
Landing— the minimum speed an airplane reaches as 
the airplane strikes the ground in normal landing 
Speed of light — the speed at which light travels, 186,300 

miles per second. 
Speed of sound— the speed at which sound waves travel 
through a medium. In air at standard sea-level condi- 
tions, some 750 mph. 
Spin— a maneuver in which an airplane descends along a 
helical path of large pitch and small radius while flying 
at a mean angle of attack greater than the angle of 
attack at maximum lift. 
Spinner— a cap fitted over the propeller hub to increase 

the streamline properties of the aircraft. 
Spiral— a maneuver in which an airplane descends in a 
helix of small pitch and large radius, the angle of attack 
being within the normal range of flight angles. 
Spoiler— a small plate fitted to the upper surface of a 
wing, the purpose of which is to disturb the smooth 
airflow and create lack of lift and increase in drag. 
Squall— (I) a sudden, brief storm, closely akin to a thun- 
derstorm but not necessarily accompanied by thunder 
and lightning; (2) a sudden, brief blast of wind of 
longer duration than a gust. 
Stability— that property of a body which causes it, when 
its equilibrium is disturbed, to develop forces or move- 
ments tending to restore the original condition. 
AMfomafiC— stability of an aircraft created by movable 
auxiliary control surfaces operated by automatic 
mechanical devices. 
Direcfiona/— stability around the vertical or yawing axis. 
Di/namic— that property which causes an airplane to 
return gradually to its normal flight position by damp- 
ing out the restoring forces after its steady flight 
position has been disturbed. 
Inherent— the property which causes an airplane to 
restore itself to normal flight position solely by the 
arrangement of its fixed parts and without help from 
the controls or other mechanical devices. 
Lateral-stability around the longitudinal or rolling axis. 
Longitudinal— stability around the lateral or pitching 
Stabilizer, horizontal— the stationary horizontal member 
of the tail assembly of an airplane to which the ele- 
vator is attached. It is responsible for longitudinal 
Stagger— a term referring to the position of the wings of 
a biplane. When the upper wing is placed slightly for- 
ward of the lower wing, stagger is positive. When the 
lower wing is placed forward of the upper wing, stag- 
ger is negative. 
Stall— the condition of an airplane which is operating at 
an angle of attack greater than the angle of attack of 
maximum lift. 
Standard atmosphere— the condition of the atmosphere 
when the barometric pressure reads 29.92 inches of 
mercury and the temperature is 59° Fahrenheit (15° 
centigrade) at sea level; used primarily as the accepted 
standard in calibrating aircraft instruments whose indi- 
cations are affected by changes in barometric pressure. 
Stationary orbit— also, in reference to earth, known as a 
twenty-four hour orbit; a circular orbit around a planet 
in the equatorial plane, having a rotation period equal 
to that of the planet. 


Step rocket— a multistage rocket. 

Straight and level— the adjustment and maintenance of an 
aircraft in three planes, vertical, lateral, and horizontal, 
i.e., (1) keeping the plane longitudinally level by use of 
the elevators, (2) keeping the plane laterally level by 
the use of ailerons, and (3) keeping the plane direction- 
ally straight by use of rudder. The movements and use 
of these three controls are later coordinated to fly the 
airplane properly. 

Stratiform— a general term applied to all clouds which are 
arranged in unbroken horizontal layers or sheets. 

Stratosphere— the upper region or external layer of the 
atmosphere, in which the temperature is practically 
constant in a vertical direction. 

Streamlining— shaping of a part so as to create the least 
disturbance of air passing around it. 

Stringers— longitudinal members connecting the bulkheads 
or rings in semi-monocoque construction. They act to 
keep these bulkheads and rings in place and to support 
the skin of the aircraft fuselage. 

Strut— a rigid, streamlined member fastened to either the 
fuselage or landing gear to support the wings. 

Subsonic— less than the speed of sound. A speed having 
a Mach number less than 1. 

Supercharger— a centrifugal pump or blower which forces 
a greater volume of air into the cylinders of an aircraft 
engine than would normally be accomplished at the 
prevailing atmospheric pressure. 

Supersonic— greater than the speed of sound. A speed 
having a Mach number greater than 1. 

Sweepback— the tapering back of the wing of an airplane 
from the wing root to the tips. 

Switch— a device for making, breaking, or changing the 
connections in an electric circuit. 

Synchronous satellite — an equatorial west-to-east satellite 
orbiting the earth at an altitude of 22,300 statute miles 
at which altitude it makes one revolution in 24 hours, 
synchronous with the earth's rotation. 

Tab — an auxiliary airfoil attached to a surface to provide 
for aerodynamic control of that surface or for trimming 
of the aircraft for any normal attitude of flight. 

Tachometer— an instrument that measures, in revolutions 
per minute, the rate at which an engine crankshaft 

Tail— (See Empennage.) 

Takeoff— the handling of an airplane leading up to and at 
the instant of leaving the ground. 

Tank, hopper — a separate compartment within an aircraft 
engine's oil tank, from which, during engine operation, 
the engine draws its oil. Also called a "hotwell". 

Taper— a gradual change in chord-length of a wing, from 
the root to the tip. Chord-length usually decreases from 
root to tip. 

Taxi— to operate an airplane under its own power, either 
on land or water, other than in actual takeoff or landing. 

Telemetering— the technique of recording space data by 
radioing an instrument reading from a rocket to a re- 
cording machine on the ground. 

Terrestrial — pertaining to the earth. 

Three-point landing— the act of contacting the ground 
simultaneously with the front wheels and tail wheel or 
skid of the aircraft. 
Throttle-a valve which regulates aii-flow through a carbu- 
retor and therefore controls the amount of fuel-air mbc- 
ture available to the cylinders of an engine. 
Throw-the displacement, or the amount of the displace- 
ment, of a control surface to either side of its neutral 
position, as in "rudder throw was measured by a rule." 
Thrust— the amount of "push" developed by a rocket; 

measured in pounds. 
Thrust augmenter— any contrivance used for thrust aug- 
mentation, as a venturi used in a rocket or an after- 
burner, etc. 
Topographical features— the representation of the natural 
geographic detail of a charted region but not including 
cultural (man made) aids to navigation. 
Torque— any force which produces or tends to produce 

rotation about the airplane's longitudinal axis. 
Tracking — the process of following the movements of a 
satellite or rocket by radar, radio, and photographic ob- 
Tracks— the actual path over the ground of an airplane in 

Trailing edge— the rear or following edge of an airplane 

wing or propeller blade. 
Tricycle landing gear-a three-wheel landing gear in which 
no tail-wheel or tail skid is used, normally consisting of 
two main wheels with an auxiliary wheel forward. Also 
applied to landing gears of this type or other devices. 
Often shortened to "tricycle gear." 
Trim tab— a small auxiliary hinged portion, inset into the 
trailing edge of an aileron, rudder, or elevator and in- 
dependently controlled. The trimming tabs are an aero- 
dynamic control for the surface to which they are 
affixed and serve to hold that surface at a position that 
will result in balancing or trimming the aiiplane for any 
normal attitude of flight, i.e., the airplane will fly hands 
Troposphere— the lower region of the atmosphere from 
the ground to the stratosphere in which the average 
condition is typified by a more or less regular decrease 
of temperature with increasing altitude, storms, and 
irregular weather changes. 
Truss— a rigid framework made up of such memf)ers as 
beams, struts, and bars (welded or bolted together to 
form triangles), and itself a structural member that re- 
sists deformation by applied loads. 
Turbofan— a jet engine of the bypass, or ducted-fan, type 
in which part of the air taken in at the front by a com- 
pressor or fan bypasses the combustion chamber to give 
extra thrust; one type has a fan at the rear. 
Turboprop — (see jet, turboprop.) 

Turbo-supercharger- a supercharger utiUzing an exhaust- 
driven turbine to operate the impeller. 

Turbulence— irregiJar motion of the atmosphere produced 
when air flows over a comparatively uneven surface, or 
when two currents of air flow past or over each other 
in difi^erent directions or at difi^erent speeds. 

Turn indicator— an instrument for indicating the direction 
and rate of turn of an airplane. It is usually combined 
with a "ball bank indicator" to show whether or not the 
controls are properly coordinated in making a turn, 
i.e., whether the airplane is slipping or skidding. 



Ultrasonic— speeds between sonic and hypersonic. 

Umbilical cord— any one of the servicing electrical or fluid 
lines between the ground and an uprighted rocket mis- 
sile or vehicle before the launch. 

Valve, butterfly— a valve operating in a tube or shaft which 
has a surface on each side of the valve axis. 

Van Alien Belt— a doughnut-shaped belt of high-energy 
charge particles, trapped in the earth's magnetic field, 
which surrounds the earth. This belt, which forms an 
obstacle to interplanetary explorations, was first reported 
by Dr. A. Van Allen of Iowa State University. Scientists 
now feel that the belt begins about 400 miles out from 
the equator and extends to a maximum of 24,000 to 
28,000 miles. 

Variation— the angle at any given place between the true 
meridian and a line drawn to the magnetic North Pole. 
It is labeled East or West, depending on which side of 
the true meridian the magnetic North Pole lies. 

Venturi tube— a short tube with a constricted throat which, 
when placed in a fluid flow and parallel to the flow, 
brings about an increase in flow velocity at the throat 
with a consequent diminished pressure within the fluid 
at the throat. 

Visibility— the greatest distance toward the horizon at 
which prominent objects can be seen and recognized. 

Visual Omni Range (VOR)— a type of ground-based radio 
aid used in navigation. 


Wash— the disturbance in the air produced by the passage 
of an airfoil through the air. 

Weightlessness— condition in free fall. May be physio- 
logically unimportant but psychologically dangerous in 
space flight. Can be avoided by spinning the space 
vehicle and simulating the effects of gravity by provid- 
ing a weight feeling with centripetal force. 

Wind— moving air, especially a mass of air having a com- 
mon direction of motion, generally limited to air moving 
horizontally or nearly so. Vertical streams of air are 
usually called convectional currents. 
Angle— the angle between the true course and the direct- 
tion from which the wind is blowing; measured from 
the true course, toward the right or left from 0° to 
Correction angle— the angle between the track and the 
heading of the aircraft. 
Wing— an airfoil or lifting surface so designed as to pro- 
duce sufficient force when in motion as to lift the 
weight of the aircraft. 

Bow— the internal construction of the wing tip that de- 
termines its shape. 
Rib— a chordwise member of the wing structure of an 
airplane, used to give the wing section its form and 
to transmit the load from the fabric to the spars. 
Root— the end of an airplane wing which is attached to 
the fuselaee. 

Yaws— an angular displacement or motion to the left or 
right about the vertical axis of an airplane. 

Zone "A" or "N"— the area in which, when flying near a 

low frequency radio range, the A( ) or N( ) is 


Bi-aignal area (or zonej— that area of a circle around a 
radio range station in which both the "A" and the 
"N" signal and two sets of identification letters can 
be heard. One signal predominates while the other 
is hccud as a "background" sound. 
Zoom— the climb for a short time at an angle greater than 

the normal climbing angle, the airplane being carried 

upward at the expense of airspeed.