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1964 
cop. 2 


i  . 


fundamentals  of 


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L  I  B  R.AFIY 

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or    ILLINOIS 

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1964 

cop.  2 


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BY 

LESLIE  A.   BRYAN 
KERMIT   B.   ANDERSON 
I.   BURNELL  APPLEGATE 
OMER   BENN 
EUGENE   L.   HAAK 
JAMES  M.   HANCOCK 
FRANCIS   B.  SCHABER 
H.  S.  STILLWELL 
W.   DALE  TRULOCK 


fundamentals  of 

AVIATION  AND  SPACE  TECHNOLOGY 

1964  Reprint 

INSTITUTE  OF  AVIATION  •  3\B  CIVIL  ENGINEERING  HALL  •  UNIVERSITY  OF  ILLINOIS  •  URBANA,  ILLINOIS 


©  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 


Foreword 


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 


Contents 


CHAPTER  1     LIVING  IN  THE  AEROSPACE  AGE      1 
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 

CHAPTER  2    HISTORY  OF  FLIGHT      1 1 
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 

CHAPTER  3    THEORY  OF  FLIGHT      16 
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 

CHAPTER  4    AIRCRAFT      24 

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 


14 


Other  Aircraft  Types      32 

Aircraft  Construction  34 

Aircraft  Inspections  34 

Supersonic  Transport  36 
Summary      36 

CHAPTER  5    THE  AIRCRAFT  ENGINE      38 

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 

CHAPTER  6    AIRPLANE  INSTRUMENTS      52 

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 

CHAPTER  7    FLIGHT  TECHNIQUE      62 

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 

CHAPTER  8    AIR  NAVIGATION      71 
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 

CHAPTER  9    METEOROLOGY      86 
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 

CHAPTER    10    AIR  TRAFFIC  CONTROL 

AND  COMMUNICATION      100 
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  0 


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 

CHAPTER    12     SPACE  TRAVEL      118 
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 

CHAPTER    13     SPACE  EXPLORATION 
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 

APPENDIX      143 


CHAPTER    1 1     THE  FEDERAL  AVIATION  AGENCY 
Government  Regulations      1  1  2 


112 


Illustrations 


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 
problems. 

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 

Aircraft   Engines 
Aircraft  Parts  and  Accessories 
Missiles 
Spacecraft 

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 
facilities. 


2        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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. 

THE  AEROSPACE  MANUFACTURING  INDUSTRY 

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 
1-) 

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. 


LIVING   IN   THE  AEROSPACE  AGE 


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 
industry. 

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. 


AIR  TRANSPORT  INDUSTRY 

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. 


J 

L'^ 

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JION 

AL 

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52 


S3 


54 


55 


56 


57        58 


59 


60 


61 


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. 


Source: 
4v(at(on 


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


DC-7C 

Jets 

Cities 

Miles 

(hours) 

(hours) 

New  York  to  London 

3,250 

12.0 

6.5 

New  York  to  Paris 

3,680 

13.0 

7.0 

New  York  to  Rio  de  Janeiro 

5,020 

18.5 

10.0 

San  Francisco  to  Honolulu 

2,420 

8.0 

5.5 

Los  Angeles  to  New  York 

2,458 

7.5 

4.5 

New  York  to  Los  Angeles 

2,458 

8.5 

5.5 

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 


4        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


RAIL  N. 

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DATA  ESTIMATED 


50 


52 


60 


62 


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 
4.) 

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 


LIVING  IN 

THE 

AEROSPACE  AGE        5 

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INSTRUCTIONAL 

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. 

Helicopters 

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


6        FUNDAMENTAIS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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 
versatility*. 

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- 
crease! 

GENERAL  AVIATION 

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 
airlines. 

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 
decade. 

The  Social  Aspect 

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


LIVING   IN  THE   AEROSPACE  AGE 


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. 


POPULATION  DISTRIBUTION 

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. 

EDUCATION 

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 
instruction. 

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 


FAMILY  LIFE 

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. 

MILITARY  OPERATIONS 

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. 


8        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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 
supremacy. 

INTERNATIONAL  AFFAIRS 

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 
relations. 

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 


LIVING    IN   THE   AEROSPACE   AGE 


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 
affairs. 

POLITICS 

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. 

Summary 

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. 

Questions 


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? 


10        FUNDAMENTALS   OF   AVIATION  AND   SPACE  TECHNOLOGY 


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- 
line. 

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 
importance. 

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 


12        FUNDAMENTALS   OF  AVIATION   AND  SPACE  TECHNOLOGY 


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 
Langley. 

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 


HISTORY  OF   FLIGHT        13 


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 


14        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOIOGY 


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. 

Summary 

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, 


HISTORY  OF  FLIGHT        15 


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, 
1903. 

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


constantly  being  set.  Round-the-world  flights  became 
commonplace. 

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. 


Questions 

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

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 
ground? 

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? 


11. 


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 
research. 

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 


THEORY  OF   FLIGHT        17 


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 
attack. 

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. 


18        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


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 


THEORY  OF   FLIGHT        19 


AXIS  OF  PITCH 


AXIS  OF  YAW 


AXIS  OF  ROLL 
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. 

Rudder 

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. 


20        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


^  \l 


1 


f 


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. 


Elevators 

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. 


Ailerons 

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- 


THEORY   OF   FLIGHT        21 


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 
airplane. 

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. 


FORCES  RUDDER  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 


22        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


Summary 

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 
drag. 

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 
drag. 

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. 


Questions 

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- 
tions? 

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? 


THEORY  OF   FLIGHT        23 


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 
components. 

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 


AIRCRAFT       25 


Figure     21 — Various  Wing  Shapes 


^ 


Figure  22 — Possible  Wing  Locations 


26        FUNDAMENTALS   OF   AVIATION   AND   SPACE  TECHNOLOGY 


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.) 

Wings 

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 


AILERON 


FLAP 


AILERON 


AILERON 


FLAP 


FLAP 


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.) 

Fuselage 

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 


STALL 


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 


28        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


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. 


AIRCRAFT       29 


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 


30        FUNDAMENTALS   Of  AVIATION   AND   SPACE   TECHNOLOGY 


OUTER 
CYLINDER 


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- 
anism. 

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. 

Powerplants 

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 
transport. 

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. 

Propellers 

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 
34.) 

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. 


AIRCRAFT       31 


Figure 
low  ar 
(blade: 
each   n 


34-1     F.ne   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  dis.ar,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- 


A=  CONSTANT  SPEED   PROP 
B=TWO  P0SITK3N  CONTR.  PROP 
C=  FIXED  PITCH  PROPELLER 


Figure  36— Propeller   Pitch   Performonce   Comparisons 


j  ,     FEATHERING 


Figure 


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 


FUNDAMENTALS   OF  AVIATION   AND   SPACE   TECHNOLOGY 


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 


AIRCRAFT       33 


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 
cables. 

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 
problem. 

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 


34        FUNDAMENTALS   OF  AVIATION   AND   SPACE   TECHNOLOGY 


© 


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 
propulsion. 

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- 
pleted. 

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. 


AIRCRAFT       35 


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. 

4.  CHECK  FUEL  AND  OIL  SUPPLY,  making 
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- 
curity. 
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 


36        FUNDAMENTALS   OF   AVIATION   AND   SPACE   TECHNOLOGY 


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. 


Summary 

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. 


AIRCRAFT       37 


Questions 

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 
boots. 

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- 
ware? 


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 


ROW 
TYPE 

Figure  43 — Aircraft    Engine   Cylinder    Arranger 


THE  AIRCRAFT   ENGINE        39 


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 ) . 


SPARK 
PLUG 


COOUNG 
FINS 


Figure  44 — Types  of  Crankshafts 


CRANK 
SHAFT 


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— 


40        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


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 
development. 

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, 


PISTON    RINGS 


CONNECTING 


COOLING  FINS 


VALVE    GUIDE 


CYLINDER    HEAD 


Figure  47 — Airplane    Engine   Cylinder   Nomenclatur 


Figure  48— Val 


THE   AIRCRAFT   ENGINE        41 

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 
are: 

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 


EXHAUST  INTAKE 


^^    ^     ^     ^     ^ 


INTAKE 


COMPRESSION 


IGNITION 


POWE  R 


EXHAUST 


Figure  49 — Slages   of  the   Four-Slroice  Cycle   Engine 


42        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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 
charge. 

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. 


THE   AIRCRAFT   ENGINE        43 


FUEL  AND  INDUCTION  SYSTEM 

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- 


THROTTLE  PRESSURE    RELIEF  VALVE 

VALVE 

FINGER 
FLOAT         STRAINER 
CHAMBER 


MAIN 
DISCHARGE   NOZZLE 


AIR 
INTAKE 


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. 


44        FUNDAMENTALS   OF  AVIATION  AND   SPACE  TECHNOLOGY 


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


IGNITION   SYSTEM 

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 


WASTE   GATE 
EXHAUST  GASES 


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 

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 
setting. 


DISTRIBUTOR    BLOCK" 
DISTRIBUTOR    FINGER 
SECONDARY    WINDING 
PRIMARY    WINDING 
CONDENSER 


FOTH  OF  MAGNETIC 
FLUX    THRU  MAGNET 


Figure  52 — Culawoy   View   of   o   Turbo  Supercharger 


LPOLE    SHOES''         ROTATING    MAGNET 
Figure  54 — Schematic  Diagram  of  an  Aircraft  Engine  Magneto 


THE  AIRCRAFT  ENGINE       45 


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. 

PLAN 

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

33,000 

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 
33,000 
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 

2200 

per  minute   should   have  9    X  or  9900  power 

2 

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 
aircraft. 

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. 


Figu. 

Tube 


56 — Reciprocating    Engine-Propeller   Combination    Enclosed 


46        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOIOGY 

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. 

COMBUSTION    CHAMBER 


COMPRESSOR 


Figure    57 — Compressor-Turbine 
(Typical    Turbojet    Engine) 


TURBINE 


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. 


Jl 


.^SPARK    PT.UG 


^COfcaOSTION     SECTION 

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 


THE  AIRCRAFT   ENGINE       47 


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 
compression. 

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 


48        FUNDAMENTALS   OF  AVIATION   AND  SPACE  TECHNOLOGY 


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. 


COMPRESSORS 

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 


THE  AIRCRAFT   ENGINE        49 


COMBUSTION   CHAMBERS 

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. 

TURBINES 

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 
diaphragm. 

EXHAUST  CONES 

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. 

THRUST  VERSUS  POWER 

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  = -. 

time 

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- 


50        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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  =  ^°^^- 


TURBOJET,  TURBOPROP,  AND  TURBOFAN  ENGINES 

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- 


COMBUSTION  CHAMBER 

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 
afterburner. 

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. 
ROCKET  PROPULSION 

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  AIRCRAFT   ENGINE        51 


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. 

ATOMIC   PROPULSION 

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. 

Summary 

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 
exhaust. 

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. 


Questions 


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 
engine? 


13. 


14. 


15. 


UNIVERSITY  Oh 
lUINOIS  LIBRARV 


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  -  ' 


nXDOD 


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


AIRPLANE   INSTRUMENTS        53 


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 
limits. 

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, 


54        FUNDAMENTALS   OF  AVIATION   AND  SPACE  TECHNOLOGY 


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 
fimctions: 

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. 


AIRPLANE   INSTRUMENTS        55 


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- 


56        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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

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. 

Tachometers 

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 
tachometers. 

MAGNETIC  TACHOMETER 

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 


Figu 


73 — Electricol  Tachometer 


AIRPLANE    INSTRUMENTS        57 


ELECTRIC   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. 


58        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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 
gage. 

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 


AIRPLANE   INSTRUMENTS        59 


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- 
ditions. 

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 
turns. 


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 
tube. 

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 


60        FUNDAMENTALS   OF  AVIATION   AND   SPACE   TECHNOLOGY 


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 


AIRPLANE   INSTRUMENTS        61 


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  0  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. 

Summary 

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 
horizon. 

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- 
peratures. 

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. 


Questions 

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 
airplane? 

4.  What  detemiines  instrument  requirements? 

5.  What  is  a  venturi  tube  used  for? 

6.  How  does  a  venturi  tube  cause  a  decrease  in 
pressure? 

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 
be? 

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- 
tion? 

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

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 
compass? 

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. 

CONTROLS 

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 
efl^ect. 


STRAIGHT  AND  LEVEL  FLIGHT 

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 


AILERON 


ELEVATOR 
PUSH    TUBE 


RUDDER 


RUDDER 
PEDALS 


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


FLIGHT  TECHNIQUE       63 

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. 

THE  CLIMB 

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 

THE  GLIDE 

.£";  ri,-,r  :;•-:•  •'•■••> -"' 

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

Jv;r4™™:h?t;ti'eer'™-'''"' 

arag  and   lift  equals   weight-and   the 


64        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


AIR  SPEED    (POWER) 


-=#^^=-4^^^=^ 


aircraft  descends  at  a  constant  rate  and  at  a  constant 
airspeed. 

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. 

THE  TURN 

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. 


LOAD 


BOMBS    AWAY 


^^^ 


FACTOR 

ATTITUDE 

AIR  SPEED -LOW 
HIGH 

LOAD- HEAVILY  LOADED 
EMPTY 

NOSE-HIGH 

LEVEL  OR  NOSE-LOW 

NOSE-HIGH 

LEVEL  OR  NOSE-LOW 

Figure   83 — The  Factors  Affecting  Attitude 


NORMAL     LIFT 


FLIGHT  TECHNIQUE        65 
^^^        CHORD  LINE 


NORMAL     LIFT 


CHORD  LINE 


CHORD  LINE 

ANGLE    OF  ATTACK 


FLIGHT    PATH 


CLIMB 


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


USE  OF  RUDDER  IN  A  TURN 

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 
position. 

OVERBANKING  TENDENCY 

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. 

LOSS  OF  VERTICAL  LIFT 

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. 

RATE  OR  TURN 

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. 

SLIPPING  AND   SKIDDING 

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. 


66        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


# 


RESULTANT      j^.  VERTICAL 

LIFT  A"      COMPONENT 

OF  LIFT 


HORIZONTAL       \ 
COMPONENT 
OF  LIFT 


WEIGHT 


CENTRIFUGAL 
FORCE 


^. 


w 


.w 


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 


FLIGHT  TECHNIQUE       67 


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 


68        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 

TRAFFIC       PATTERNS 


leave  traffic  Ii5° 


I 


Heavy  or  fast 
aircraft  departure 


HEAVY,  FAST  AIRCRAFT 
•^>     LIGHT,  SLOW  AIRCRAFT 

THE  ABOVE  PATTERNS  WILL  BE  USED  FOR  ALL  WIND  DIRECTIONS 


Figur, 


FLIGHT  TECHNIQUE       69 


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. 

Summary 

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 
airborne. 

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. 


70        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


Questions 

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 
turned. 

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 
approach? 

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 


72        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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. 


^mfje^ 


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^ 


^"'^THT^U^yy^'' 


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


Figure  91 — Lines  of   Lolitude 


AIR  NAVIGATION        73 


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. 


74        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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 


Figu 


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

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 
destination. 

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- 


AIR  NAVIGATION       75 

1224 


Figure  95 — Sectional  Chart 


FUNDAMENTALS   OF  AVIATION   AND  SPACE  TECHNOLOGY 

AERONAUTICAL   SYMBOLS 


AERODROMES 


AERODROMES   WITH    FACILITIES 


o 

o 


^ 


AERODROMES   WITH    EMERGENCY 
OR    NO   FACILITIES 
LAND  WATER 


Joint  civil  and  military 
Military 


X 


Landing  area 
Anchorage 


Heliport  (Selected) 


^  o 


WINSTON 
2427  L  48 

Airport  of  entry 
GCA    ILS   DF 

278  119.5  126.2 
257.8     122.7G 


Cont 
278 

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 

L^^P  AERODROME    DATA 

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 


WATER 
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 


NAS   NORFOLK 

00  L  S250 

3053 


learest  town 


name 


a\  advi 


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

AIR    NAVIGATION  LIGHTS 

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 


Lightship 

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


4. 


indicoted.  Man 


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


RADIO    FACILITIES 

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 


JSPR 
'•|J71 


Radio  broadcasting  station 


EVERETT 
233 

20m  &  30m-40ni 


Radiobeaco 
(homing) 


1.  nondirectionaL 
(With  voice' 


Outer  marker 

(Shown  when  con 


radiobeacon  _QLOMc 

ponent  of  airway  system) 


090°-*- 


, LOM , 

—••[359  EW     -^ 


cation  station- _G> .^FORT   WORTH 

365 


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 
distortion. 

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 


AIR  NAVIGATION        77 


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.) 


MERIDIANS 


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  0  degrees  running  through  the  Great 
Lakes  south  to  Florida.  These  lines  of  magnetic  vari- 


Figure  98 — Measuring  a  True  Course  line  with  Protractor 


78        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


to*           IS- 

Kf      !■      rf       5"       KC            «■        20' 

/  — 
1 

1 — 

\^K. 

.<•-— ~— "-^^^^^ 

^ 

4-                                             5-                                 0- 

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


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 
oirplone. 


blowing 


plane  a   definite  amount 
II    concel    out    the 


drifting 


: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 


AIR  NAVIGATION        79 

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 
determined. 

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 


CONTACT  FUGHT  LOG 


TIME  OF  DEPARTURE 

DISTANCE 

ELAPSED 
TIME 

CLOCK 
TIME 

GS 

CH 

REMARKS 

CHECK-POINTS 

^^-t^ 
f^^" 

^^'i^ 
f^^ 

■.■^^■S'-'-^ 
^^^ 

BRACKETS.  WEATHER 
RADIO  DATA.  ETC. 

1. 

^^^ 

^^--^ 

^.^^ 

^,^^ 

^//^ 

2. 

^^-^ 

^^^ 

^./-^ 

^^/-^ 

^^ 

3. 

^,^^^ 

^^ 

^^^ 

^.-^ 

^^ 

4. 

^^^ 

^^-^ 

^^ 

^^ 

6. 

^^^ 

^^.-^ 

^^ 

^^ 

^^.^ 

6. 

^.-^^ 

^^^ 

^/^^ 

^-^ 

Figure    102 — Contact   Flight   Log 


80        FUNDAMENTALS   OF  AVIATION  AND   SPACE  TECHNOLOGY 


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 


AIR  NAVIGATION        81 


RADIO    AIDS    TO    NAVIGATION 

O     VHF    OMNI    RANGE  (VOR) 

'\2     TACAN 

^     VORTAO 

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


m 


r  LMM  Beacon 

anO'Consol  Statu 
steal  Broadcast  S 
Marker  Beacons 

CXDb 


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aci 

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NAVIGATION    AND    PROCEDURAL 

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INFORMATION 
Official  Time  Zone 

IRWAYS    DATA 

International  Boundary 

sory  Reporting  Poi 

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,      Designates  char 
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P,      than  facilities  /J, 

r        Minimum  Crossing  Altitude     r 
/  (MCAl  / 

35 

J. 


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35  Mileage  to  Facility 

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


i  to  Fa 


Illy 


URSPACE    INFORMATION 

Air  Defense  Identilicat 
Zone  (ADIZ  -  CADIZ) 


THE    US     FEDERAL   GOVERNMENT 
DISCLAIMS    RESPONSIBILITY    FOR 
NON-FEDERAL  NAVIGATIONAL    FAC- 
ILITIES 


5  depicted  within  this  boundary-) 
tlRSPACE    RESERVATIONS 


Rp.t.icled  Area 

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ALL    MILEAGES 

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NAUTICAL         1 

(EXCEPT  AS 

NOTEDI 

.1 

Figure  104 — Radio  Facility  Chart  legend 


82        FUNDAMENTALS   OF  AVIATION   AND   SPACE   TECHNOLOGY 


RADIO  SYSTEM 


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 


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


84        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


POSITION  THE  STATION 


MOVEMENT  OF  NEEDLE  INDICATES  W/IND  DIRECTION 
(NEEDLE  MOVES  TO  LEFT,  WIND  IS  FROM  THE  LEFT). 


IF  NEEDLE  MOVES, /TURN  AIRCRAFT  TO  RE-CENTER  IT. 


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"  ( ). 


1.    AFTER  TUNING  STATION,  TURN  AIRCRAFT  TO  ZERO  OM  THE 
RADIO  COMPASS  AZIMUTH  NEEDLE. 
Figure   108 — The   Rolaling    Needle   of   the   Aulomalic    Direction    Finder 
(ADF) 


Figure   109 — Aircraft    VHF   Tronimitter   and    Recei' 


AIR   NAVIGATION        85 


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 
references. 

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. 

Summary 

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 
Projections. 

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. 


Questions 

1.  Why  is  navigation  important  to  any  means  of 
transportation? 

2.  What  is  air  navigation? 

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

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 
bands? 

11.  What  advantage  does  a  pilot  have  using  a  VHF 
radio? 

12.  Explain  briefly  the  fundamentals  of  VOR. 

13.  List  the  equipment  necessary  for  celestial  navi- 
gation. 

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

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


Chapter  O  Meteorology 


NORTH  POLE  EQUATOR 

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. 


METEOROLOGY        87 


TEMPERATURE 

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 
processes. 

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. 

PRESSURE 

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. 

MOISTURE 

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, 


88        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


CIRROSTRATUS 


ALTOSTRATUS 


10,000  FT. 


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


METEOROLOGY        89 


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. 

CLOUDS 

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 
formations: 

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 
flight. 

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 
weather. 

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. 


90        FUNDAMENTALS  OF  AVIATION  AND  SPACE  TECHNOLOGY 


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 
feet. 


CIRCULATION 

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  AAASSES  AND  FRONTS 

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 


METEOROLOGY       91 


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 

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 

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. 


92        FUNDAMENTALS   OF  AVIATION   AND  SPACE  TECHNOLOGY 


JC^'-X^/i^-^^ ^^ 


Figure    Hi — Avoiding  Convectt^e   Turbulence  by  Flying  above  Cumulus 
Clouds 


LOW   WIND   SPEED 
(BilOV/  ABOUT  20  MPH) 


HIGH   WIND   SPEED 
(ABOVE  ABOUT  20  MPH) 


Figure    116 — Surface    obstructions    cause    eddies    and     other    irregular 
wind  movements. 


WARM    AIR 


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 

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 


METEOKOLOGY       93 


■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. 
ICING 

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 


94        FUNDAMENTALS   OF  AVIATION  AND   SPACE  TECHNOLOGY 


MKC 


S  I150M250[4R-K  fl32f/58/56  1 17|/993/ 


©55/  RB05  eV©R18VR32 


SKY  AND  CEILING 

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  0  1  sky  cover 
(D^Scallered     0  1  to  less  than  0  6  sky  cover 
(I)  =  Broken     0  6  to  0  9  sky  cover 
®  .Overcasl     More  than  0  9  sky  cover 
-  =Thin  (W  hin  ptihvcj  iu  ihi  jh..n  >>nih.iK 
-X=Parttal  Obscuration     0  1  to  less  than  1.0  sky  1 

1  0  sky  hidden  by  precipitation 


X=Obscu 


VISIBILITY 

Reported  In  Statute  Miles 

WEATHER  SYMBOLS 


INTENSITIES 

'  Llttht     —    LlRht     (n 


OBSTRUCTION  TO  VISION  SYMBOLS 

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» 

WIND 

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 


ALTIMETER  SETTING 


CODED  PIREPS 


RUNWAY  VISUAL  RANGE  (RVR) 


DECODED  REPORT 


-;-s- 


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. 

HOURLY  SEQUENCE  REPORTS 

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. 


PILOT  REPORTS 

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. 

AAAPS 

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. 

WINDS  ALOR  REPORTS 

Weather  bureau  stations  also  periodically  check  the 
winds  aloft.   (Figure  123.)  This  wind  information  is 


METEOROLOGY       95 


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^^ht 

r^i^^i^--^'^>  ^--^x^ 

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K,jj5^y 

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96        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


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^°^  i2S^ 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. 


THE  CIRCLED  REPORT  IS  READ: 


01  309 

20812 

C515 

43616 
3421 


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. 

AREA  FORECASTS 

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. 

TERMINAL   FORECASTS 

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 
others. 


Summary 

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. 


METEOROLOGY       97 


FCST  O7C-I9C 

MINN   N  DAK   S  DAK 

CLDS  AND  WX.  HEIGHTS  MSL  UNLESS  NOTED.  CNDS  IN  5O  MILE 
WIDE  SQAL  LINE  ZONE  THRU  SERN  MINN  MOSTLY  60©  BUT 
VSBYS  BRFLY  2-k   MIS  AND  CIGS  NEAR  20  HND  ABV  GND 
WITHIN  HVYR  TSTM  AREAS.  THIS  SQAL  LINE  WILL  MOVE  SEWD 
ABT  25  MPH  AND  DSIPT  BY  ABT  IOC.  STRATUS  OVC  5-IO  HND 
ABV  GND  IN  NERN  MINN  WILL  CLR  BY  MID  MRNG  BUT  LCL 
AREAS  LOW  CLDS  6-12  HND  BRKN  ABV  GND  WILL  PERSIST 
UNTIL  ABT  NOON  ALNG  THE  SLOW  WOVG  COLD  FNT  FROM  INTER- 
NATIONAL FALLS  TO  HURON  AT  O5C  AND  STNRY  FROM  THERE 
WWD  TO  BYND  RAPID  CITY.  10-12  THSD  BRKN  GNRL  IN  CNTRL 
AND  WRN  PTNS  DAKOTAS  WITH  A  FEW  HI  LVL  TSTMS  DVLPG  IN 
LATE  AFTN 

ICG.  LGT  TO  OCNLY  MDT  ICGIC  ABV  120  XCP  LCLY  HVY  IN 
TSTM  AREAS.  FRZG  LVL  I2O-II4.O 

TURBC,  MDT  TO  HVY  IN  TSTMS 

OTLK  19c  SUN  TO  O7C  MON.  TSTMS  CNTRL  AND  WRN  DAKOTAS 
WILL  END  BY  ERY  AFTN  BUT  ANTHR  SQAL  LINE  WILL  DVLP 
FROM  NERN  MINN  TO  SERN  CORNER  S  DAK  BY  I9C  THAT  WILL 
MOVE  EWD  ABT  2^  MPH  WITH  LCLY  SVR  CNDS  AND  THEN  DSIPT 
SHORTLY  AFT  MIDN.  ELSW  UNRSTD  VSBYS  AND  NO  CLDS  BLO 
10  THSD  MSL. 


PLAIN    LANGUAGE    INTERPRETATION 

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 


98        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


KEY  TO  AVIATION  WEATHER  FORECASTS. 


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. 

ADVISORIES  FOR  LIGHT  AIRCRAFT      advises  oirmen  in 

CEILING      Identified  by  Ihe  leller  "C" 

ClOUD  HEIGHTS;    In  hundreds  ol  feel  above  the  station 
CLOUD   LAYERS      Stoted  in  oscend.ng  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 

channels. 

Examples  of  TERMINAL  FOttECASTS: 

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 

Examples  of  WINDS  ALOFT  FORECASTS: 

5-2030J      5,0C!0«Sl  ..ndl.om  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. 

U.  S.  DEPARTMENT  OF  COMMERCE 


WEATHER  BUREAU 


WASHINGTON  25,  D.  C. 


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. 


METEOROLOGY       99 


Questions 

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 


AIR  TRAFFIC  CONTROL  AND  COAAMUNICATIONS        101 


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 
conversation. 

To  hmit  the  possibility  of  error  in  the  transmission 
of  names  or  difficult  words,  a  standardized  phonetic 
alphabet  has  been  devised  to  identify  individual 
letters: 


"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 

Phrase 

Roger 

Wilco 
Acknowledge 

Say  again 
I  say  again 
Over 

Out 


Meaning 

Message  received  and  meaning  un- 
derstood. 

Will  comply  with  instructions. 
Let  me  know  you  have  received  and 
understood  my  message. 
Repeat. 
I  will  repeat. 

Transmission  ended;  I  expect  a  re- 
ply. 

Communication  ended;  no  reply  ex- 
pected. 


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." 


102        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOLOGY 


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- 
ditions. 

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 
takeoff. 

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, 


AIR  TRAFFIC  CONTROL  AND   COMMUNICATIONS        103 


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. 
Over." 

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. 

Over." 
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. 

EXAMPLE: 

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." 


104        FUNDAMENTALS  OF  AVIATION  AND  SPACE  TECHNOIOGY 


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. 
Over." 

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 
base." 

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 
heading. 

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 
altitude. 

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 


All  TRAFFIC  CONTROL  AND  COMMUNICATIONS        105 


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 
airways. 

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- 
ment. 


106        FUNDAMENTALS  OF  AVIATION  AND  SPACE  TECHNOLOGY 


wrrioc.     \jr      uincv^iun 

DEPUTY     DIRECTOR 

COMMUNICATIONS 
PLANS     AND     REVIEW 
STAFF 

MANAGEMENT     AND 
PERSONNEL     STAFF 

MILITARY 
COMMAND     LIAISON 
DIVISION 

OPERATIONS 
EVALUATION 
DIVISION 

PROGRAM 
CONTROL 
DIVISION 

SYSTEMS 

REQUIREMENTS 

DIVISION 

AIRSPACE 

UTILIZATION 

DIVISION 

OPERATIONS 
STANDARDS 
DIVISION 

REGULATIONS 
AND     PROCEDURES 
DIVISION 

FLIGHT 

INFORMATION 

DIVISION 

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: 

1.  AIR   ROUTE   TRAFFIC   CONTROL 

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.) 

2.  TOWERS 

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. 


3.    FLIGHT  SERVICE  STATIONS 

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 


AIR  TRAFFIC  CONTROL  AND  COMMUNICATIONS        107 


Figure   132 — A  Typical   Flight  Plan 


108        FUNDAMENTALS   OF  AVIATION  AND  SPACE  TECHNOIOGY 


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. 


Pilot: 


Ground 
Control: 


Pilot: 


"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 
one." 
"Roger,  five  eight  Hotel." 


The  aircraft  is   now  cleared  to  just  short  of  the 


__       fO  flOHID* 


,-  / 


.DAWN  j'o" 


^-? 


'OOo 


llii  «'"   LIBERTY 


ONROWA     i 

I  I  u/uirci  / 

Figure   133 — A  Portion  of  a  Radio  Focility  Chart 


AIR  TRAFFIC  CONTROL  AND   COMMUNICATIONS        109 


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: 

Pilot: 


"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 


Over." 

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. 
Over." 

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. 

Over." 
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." 


no        FUNDAMENTALS  OF  AVIATION   AND   SPACE  TECHNOLOGY 


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. 
Over." 
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. 


Summary 

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- 
lision. 

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 
aircraft. 

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. 


AIR  TRAFFIC  CONTROL  AND  COMMUNICATIONS        III 


Questions 

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- 
sage? 


6.  What  are  the  functions  of  ARTC? 

7.  In  the  absence  of  radio,  how  does  a  tower  control 
traffic? 

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 
general. 

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). 


THE  FEDERAL  AVIATION  AGENCY        113 


Bute 

ou   of 

Nati 

nol 

Capi 

Gl 

Airp 

ins 

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- 
merce. 

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- 


114        FUNOAMENTAIS  OF  AVIATION  AND  SPACE  TECHNOLOGY 

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: 

Subchapter  A   DEFINITIONS 

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 

Standards. 
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 

Crewmembers. 
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. 

Subchapter   F  AIR   TRAFFIC   AND   GENERAL 
OPERATING   RULES 

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 

Rockets. 
Part  103— Transportation  of  Dangerous  Articles  and 

Magnetized  Materials. 
Part  105— Parachute  Jumping. 


Subchapter   B    PROCEDURAL   RULES 

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- 
craft. 

Part  29— Airworthiness  Standards:  Transport  Rotor- 
craft. 

Part  33— Airworthiness  Standards:  Aircraft  Engines. 

Part  35— Airworthiness  Standards:   Propellers. 


Subchapter   H   SCHOOLS   AND   OTHER 
CERTIFICATED   AGENCIES 

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- 
ports. 

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. 


THE   FEDERAL  AVIATION  AGENCY        115 

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. 


Subchapter  K  ADMINISTRATIVE  REGULATIONS 

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 


116       FUNDAMENTALS  OF  AVIATION   AND   SPACE  TECHNOIOGY 


AIRCRAFT       WITHIN 
THIS     AREA     CONSIDERED 
OVERTAKING     AIRCRAFT 


AIRCRAFT    ON    CROSSING      COURSES 


'!f 


■^, 


AIRCRAFT     APPROACHING     HEAD-ON 
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 


OVERTAKING    AIRCRAFT 


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   FEDERAL  AVIATION   AGENCY         tI7 


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.) 


Summary 

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- 
lations. 

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. 


Questions 

1.  Why    are    government    regulations    necessary    in 
aviation? 

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- 
ating. 

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- 
mospheres. 

7.  Pluto,  the  most  distant  planet,  is  relatively  un- 
known. 

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 


SPACE   TRAVEL        119 


A  MERCURY 
B  VENUS 
C  EARTH 
D  MARS 


E  JUPITER 
F  SATURN 
G  URANUS 
H  NEPTUNE 
I  PLUTO 


Figure   139 — The   Solar  Syslen 


Planets  of  the  Solar  System 


Mean 

distance 

Equator- 

Orbital 

Escape 

from  Sun 

ial  Di- 

Velocity 

Velocity 

Gravity  at 

(million 

length 

Period  of 

ameter 

(miles  per 

( miles  per 

Surface 

Planet 

miles) 

of  year 

Rotation 

(miles) 

second ) 

second ) 

(earth  =  l) 

Mercury 

36.0 

88.0  days 

88  days 

3,000 

29.7 

2.2 

0.27 

Venus 

67.2 

224.7  days 

unknown 

7,600 

21.7 

6.3 

0.85 

Earth 

93.0 

365.25  days 

1  day 

7,900 

18.5 

7.0 

1.00 

Mars 

141.5 

1.88  years 

24  hr.  37  min 

4,200 

15.0 

3.1 

0.38 

Jupiter 

483.3 

11.86  years 

9  hr.  55  min. 

88,700 

8.1 

37.0 

2.64 

Saturn 

886,1 

29.46  years 

10  hr.  14  min. 

75,100 

6.0 

22.0 

1.17 

Uranus 

1,782.8 

84.02  years 

10  hr.  40  min. 

30,900 

4.2 

13.0 

0.92 

Neptune 

2,793.5 

164.79  years 

15  hr.  40  min. 

33,900 

3.4 

14.0 

1.12 

Pluto 

3,675.0 

248.43  years 

unknown 

3,500 

2.7? 

6.5? 

0.9? 

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 


120        FUNDAMENTALS  OF  AVIATION   AND  SPACE  TECHNOLOGY 


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. 

EARTH'S  ATMOSPHERE 

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 
protected. 

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 
terminology: 

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. 


SPACE  TRAVEL        121 


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 
boundaries. 

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 
Chiozza. 

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 
sound. 

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 
public. 

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 


122        FUNDAMENTALS   OF  AVIATION   AND  SPACE  TECHNOLOGY 


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 
citizens. 

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- 
ance. 

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 

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 


SPACE  TRAVEL        123 


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 
tank. 

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. 


LIQUID    FUEL    ROCKET 


^(MiusiiM  (umn 


SOLID     FUEL     ROCKET 


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 
thrust. 

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 
kilowatts. 

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 
thrust. 

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. 

GUIDANCE 

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 


124        FUNDAMENTALS  OF  AVIATION  AND  SPACE  TECHNOIOGY 

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 
(SSIA)." 

ORBITS 

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- 


SPACE  TRAVEL        125 

C  D 


PLANET 


A     CIRCLE 
B     ELLIPSE 
C     PARABOLA 
(Parallel  to 
line  XY) 
D     HYPERBOLA 

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 
satellite. 

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 

APOGEE 


PERIGEE 

Figure   143 — The  Satellite  Ellipse 


126        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


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 
surface. 

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 
moon. 

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- 
tic. 

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. 


ATMOSPHERE   REENTRY 

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 
atmosphere. 

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. 

PHYSICAL   PROBLEMS 

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 
more. 

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 


SPACE  TRAVEL        127 

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. 


128        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


Figure   144 The   USAF  Titan   ICBM   is   launched   from   Cape  Conaveral,  Florida,  on  another  successful  5,000   mile  flight.        OfTiciol   USAF  photo. 


SPACE  TRAVEL        129 


Summary 

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 
propulsion. 

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. 
Questions 

1.  Name  the  planets  which  revolve  around  the 
sun. 

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 
asteroid? 


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 
stability. 

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 
flight. 

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- 
tion? 

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 
rocket? 


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- 
mendous. 

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 
mankind." 

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." 


SPACE   EXPLORATION        131 


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 
nations. 

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.) 

SPACECRAFT  TOTALS' 

Earlh  Lunar  Solar 

Satellites        Impact  Orbit  Total 


United  States 

Spacecraft  Orbited 


Russian 

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 

EXPLORER   SATELLITES 

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 


132        FUNDAMENTALS   OF   AVIATION   AND  SPACE   TECHNOLOGY 


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. 

PIONEER   SATELLITES 

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. 

PROJECT  SCORE 
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 
space. 

DISCOVERER   SATELLITES 

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. 

TRANSIT  SATELLITES 

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- 


SPACE   EXPLORATION        133 


weather  air  and  sea  navigation  system  than  is  presently 
available. 

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. 

TIROS  SATELLITES 

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. ) 

MIDAS   SATELLITES 

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. 

ECHO   SATELLITE 

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. 

SAMOS  SATELLITES 

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 


134        FUNDAMENTALS  OF   AVIATION   AND   SPACE  TECHNOLOGY 

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 
Prospector. 

RANGER  SPACECRAFT 

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. 

SURVEYOR   SPACECRAFT 

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.) 

MARINER  AND  VOYAGER   SPACECRAFT 

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 
planned. 

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.) 


SPACE   EXPLORATION        135 


on  the  atmosphere.  The  initial  launch  is  scheduled 
for  1967. 

Future  Space  Projects 

METEOROLOGICAL  SATELLITES 

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. 

COMMUNICATIONS  SATELLITES 

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. 

OBSERVATORY   SATELLITES 

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 
earth. 

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. 

X-15  ROCKET  PLANE 

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. 


136        FUNDAMENTALS  OF  AVIATION  AND  SPACE  TECHNOLOGY 


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 

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, 
1962. 

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 
instruments. 

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. 


SPACE   EXPLORATION        137 


A.      ESCAPE    TOWER 


B.     ANTENNA    HOUSING 


PRESSURIZED 

CREW    COMPARTMENT 


FIGURE   148— MERCURY  CAPSULE 


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 
light. 

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. 


138        FUNDAMENTALS   Of   AVIATION   AND   SPACE  TECHNOLOGY 


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, 


COMMUNICATIONS 


MAIN  fr  RESERVE 
CHUTES 


side  hatch 
ihstrument\   window 

PANEL      \ 


ANTENNA  HOUSING  \jPERI«^0« 


/—  iMM  /rtiTirrrti 

^^^'^n/- MENTAL 
ROLL  CONTROL  JET  CONTROL 

SYSTEM 


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 

operations 

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. 

PROJECT  GEMINI 

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 


SPACE   EXPIORATION        139 


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 

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 
steps. 

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. 

COMMUNICATIONS 

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. 


UO        FUNDAMENTALS  Of  AVIATION   AND  SPACE  TECHNOLOGY 


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. 

WEATHER 

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. " 

ADDITIONAL  RESEARCH  BENEFITS 

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. 

Summary 

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 


SPACE   EXPLORATION        Ml 


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. 


Questions 

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- 
cury? 

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 
Sink"? 

14.  What  are  Prospector  spacecraft  designed  to  ac- 
complish? 

15.  What  was  unique  about  the  Transit  IIA  satellite? 

16.  Why  were  Midas  satellites  launched? 

17.  Describe  five  different  by-products  of  space  tech- 
nology? 

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? 


142        FUNDAMENTALS  OF  AVIATION   AND  SPACE   TECHNOLOGY 


NASA'S  PROPOSED   1964  LAUNCH   PROGRAM' 


Payload  Wt.  (lb.) 


Purpose 


MANNED   FLIGHT: 

Gemini 

MANNED   FLIGHT  DEVELOPMENT: 

Gemini 

Gemini 
Apollo 
Apollo 
Apollo 
Apollo 

LUNAR,  PLANETARY: 
Mariner  C  (2) 
Ranger  (4) 
Surveyor  (2) 

SCIENCE: 

Solor  Observatory  (2) 

Ariel-2(UK-S-52) 

Explorer  (S-66) 

Explorer    (IMPB) 

Explorer  (5-3C) 

COMMUNICATIONS: 

Syncom 

Echo  2 

Relay 

METEOROLOGY: 

Nimbus 

Tiros 


'     186 

Ballistic 

Ballistic 

Ballistic 

200 

200 


Mars 
AAoon 


300 

174-939 

575-851 

126-172^00 

173-10,350 


22,300 

641-816 

1 ,298-4,606 


575 

400 


7,000 

7,000 
22,500 
22,500 
22,500 
22,500 


570 

804 

2,100 


490 
165 
110 
135 
100 


75 
650 
172 


650 

285 


Vetiicle-copsule   compatibility 

Systems   qualification 
Launcli  vctiicle  test 
Launch  vehicle  test 
Lounch  vehicle  test 
Launch  vehicle  test 


Flyby 

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. 


OFFICIAL  WORLD  RECORDS 


Competition 


Country 


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 

(claimed) 
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 

(claimed) 
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. 


Appendix 


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- 
sengers. 

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 
variation. 

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 
region. 


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. 


144        FUNDAMENTALS   Of   AVIATION   AND   SPACE   TECHNOLOGY 


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 
level. 
Amphibian— an  airplane  designed  to  rise  from  and  alight 

on  either  water  or  land. 
Aneomometer- an  instrument  for  measuring  the  speed  of 

wind. 
Angle— 

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 
gear. 
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 
planet". 
Astro — a  prefix  meaning  "star"  or  "stars"  and,  by  extension, 
sometimes  used  as  the  equivalent  of  "celestiaF,  as  in 
astronautics. 
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 
location. 

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 
two. 

Azimuth— the  initial  angle  or  direction  between  true  North 
and  a  great  circle  course. 


B 


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- 
ance. 

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. 
Barometer— 

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 
tube. 
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. 


APPENDIX        145 


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- 
ence. 

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- 
craft. 

Blades- 
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 
dirigible. 

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 
visibility. 

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 
aircraft. 

Bucket— one  of  the  blades  or  vanes  attached  to  the  tur- 
bine wheel  in  a  jet  engine  or  to  the  wheel  of  a  gyro- 
scope. 

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 
occurs. 


Calibrated  Air  Speed— (See  Airspeed.) 

Camber— the  curvature  of  the  upper  or  lower  surface  of 
an  airfoil  with  respect  to  its  chord. 

Cantilever— 

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 
bank. 

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. 

Chord— 

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- 
nal. 

Climate— the  natural  weather  conditions  of  any  region  or 
portion  of  the  earth. 

Climb— the  action  of  an  airplane  when  ascending  under 
power 


146        FUNDAMENTAIS  OF  AVIATION   AND  SPACE  TECHNOLOGY 


Clouds— 

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 
sky. 

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. 
Compass- 
Card— a   card   graduated   in   degrees   from   0'^    to   360° 
rigidly    mounted    to    and    actuated    by    the    compass 
needle. 
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 

capacitor. 
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. 
Control— 

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 
operated. 
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 
360°. 
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- 


APPENDIX        147 


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. 

Deviation— 

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 
aids. 

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 

lift. 
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 
intensity. 

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 

phenomena. 
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 

failure. 
Fin— an  approximately  vertical   fixed   or  adjustable   airfoil 

attached  to  the  tail  of  an  airplane  to  provide  directional 


148        FUNDAMENTALS   OF  AVIATION   AND   SPACE  TECHNOLOGY 


Stability. 
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 
satellite. 

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 
ground. 

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. 


APPENDIX        149 


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. 

Heading- 
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 
sound. 

Hypoxia— oxygen  deficiency  in  the  blood  in  high-altitude 
flight,  impairing  phvsical  faculties.  Occurs  at  about 
20,000  feet. 

1 

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 
endures. 

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 
planets. 

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 
cylinders. 

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 
miles. 

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 


150        FUNDAMENTALS  Of   AVIATION   AND   SPACE   TECHNOLOGY 


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 
rest. 
Area— that  portion  of  the  field  available  for  takeoft's  and 

landings. 
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  0  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 
blade. 

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 
discharge. 

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 
flight. 
Full— empty  weight  plus  useful  load.   Also  called  gross 

weight. 
Pay— that  part  of  the  useful  load  from  which  revenue  is 

derived. 
Useful— the  crew  and  passengers,  oil  and  fuel,  ballast, 
other  than  emergency,  ordnance  or  portable  equip- 
ment. 

Loading— 

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 
0  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- 
tributor. 

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. 

Mile- 

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". 

N 

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. 

Navigation— 

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 
rocket. 


152        FUNDAMENTALS  OF  AVIATION   AND  SPACE  TECHNOLOGY 


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 
both. 
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 
mph. 
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 
earth. 

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 
ground. 
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 
surface. 
Protractor— an  instrument  for  laying  down  and  measuring 

angles  on  paper,  used  in  drawing  and  plotting. 
Psi— the    standard    abbreviation    for    "pounds    per   square 

inch." 
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 
facility. 
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. 
Radio— 

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 
station. 
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 
critical. 
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 

rays. 
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 
body. 

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- 
work. 

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 
stretching. 

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 
spaces. 

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 
control. 

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 
(snowflakes). 

Soar- the  art  of  flying  without  engine  power  for  prolonged 


154        FUNDAMENTALS  OF  AVIATION   AND  SPACE  TECHNOLOGY 


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. 
Space— 

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- 
bustion. 
Speed— 

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 

conditions. 

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 
attitude. 
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 
axis. 
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 
stability. 
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. 


APPENDIX        155 


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 
turns. 

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- 
servations. 
Tracks— the  actual  path  over  the  ground  of  an  airplane  in 

flight. 
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 
off. 
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. 


156        FUNDAMENTALS  OF  AVIATION  AND  SPACE   TECHNOLOGY 


u 

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. 

W 

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 
180°. 
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 

predominant. 

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. 


w