File #1338: "Power for Aircraft Workbook.pdf"

Power for Aircraft Workbook.pdf

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Major General Walter R. Agee, USAF
National Commander
Civil Air Patrol
Dr. Mervin K. Strickler Director of
Aviation Education Civil Air Patrol

PREFACE

The exercises and activities prescribed in this
workbook will help you attain the purposes of each
lesson. These purposes will be brought to your
attention by your instructor. No exercise is to be
attempted until your reading assignment has been
completed. Do not attempt the exercises until you have
made preparation after planning with the instructor and
paying heed to his presentation at the first lesson
session.
Do not hesitate to use every method at your command
in order to obtain essential information. Observe, read,
ask questions of your instructor and the resource
people that visit your classroom. You will note that
lessons are numbered in accordance with a natural
sequence and not with reference to a particular
workbook; for example, the first lesson of the
workbook: Aircraft in Flight is Lesson VII; that of the
workbook: Power for Flight is Lesson XIV. This
procedure is also used to identify the lesson plans of
the several booklets of the Instructor Guide series.
By means of a key your instructor will help you correct
Exercises 1, 2, and 3 of each lesson. Since it has not
been possible to key the responses to Exercise 4, the
quality of these should be appraised during discussion
by students and instructor.

HAROLD E. MEHRENS, Editor
PRICE 15 CENTS PER COPY

POWERFORAIRCRAFT
LessonXlV
EXERCISE NO. 1
(You have 5 minutes to complete this exerciseJ Place a T in the
blank space which precedes a true statement; place an F in the
blank space which precedes a false statement.
a .............. Without a dependable power plant, the airplane could
not have been put into practical use.
b………… Before the Wright Brothers made their historic flight at
Kitty Hawk in 1903, men had flown in man carrying gliders.
c. .................. From the outset, aircraft power plants have been
reliable machines
d…………. The aircraft engine is a complete power unit and
does not depend on related systems to perform its function.
e ................ The principles of the six simple machines have no
application to aircraft power plants.
f ................. The first task of any engine is to convert potential
energy into kinetic energy.
g ................. Energy, once created, cannot be changed into
another kind of energy.
h ............. Practically all aircraft engines are external combustion
engines.
i ................ Robert Boyle (1627-1691) discovered that the
pressure of a confined gas is directly proportional to its
temperature.
j ……………….. internal combustion engines have pistons that
turn a crank shaft by means of a connecting rod.

EXERCISE NO. 2
(You have 10 minutes to complete this exercise.)
Fill in the blank spaces with the word, or words, that properly complete the statement.
a. When the pressure of a gas is doubled, its volume is ………………………………….. by one-half.
1

b. The ……………………, one of the six simple machines, may be
regarded as an inclined plane wrapped around a shaft

d. The internal combustion engine puts to practical use the two principles
discovered by

c. One characteristic of energy is that although it cannot be created
nor destroyed, it can be ……………………………………….
d. A mixture of fuel, such as gasoline and air, has
………………………………………… energy,
e. Work is defined as force times ..................................................

1. Orville and Wilbur Wright
2. Generals Eaker and Spaatz
3. Robert Boyle and Jacques Charles
4. Charles A. Lindbergh
e. The power generated by an aircraft reciprocating engine is productive only
when harnessed to an airplane propeller or helicopter rotor by a
1. Control System
3. Transmission System
2. Carburetor
4. Pulley System

f. The child's teeter totter on the playground is an example of the
………………….
g. The wedge is a movable …………………………………….
h. In ………………….. the then Major Carl Spaatz and Captain Ira C.
Eaker kept the …………………………………. aloft
for over …………………………
days.
i. It is the ..............................................................................
that makes sustained flight possible.
j. Energy in action is called .............................................
energy.

EXERCISE NO. 3 (You have 5 minutes to
complete this exercise.)
Draw a circle around the number preceding the phrase that makes the
statement most correct.
a. It may be that the greatest accomplishment of the Wright Brothers was to design and
build, with the help of Charles Taylor, the first successful
1. Internal combustion engine
3. Aircraft power plant.
2. Soaring plane.
4. Commercial air field.
b. The crank shaft of an internal combustion engine is an adaptation of

1. The screw.
3. The pulley
2. The wheel and axle
4.The piston rod.
c. The first man ever to make a balloon ascension was
1. Jacques Charles
3. Octave Chanute 2. Charles Taylor
4. Orville Wright

EXERCISE NO. 4
(You have 15 minutes to complete this exercise.)
1 . Wr i t e a p a r a g r a p h e x p l a i n i n g t h e p r i n c i p l e s d i s c o v e r e d b y R o b e r t
Boyle and Jacques Charles. How are these principles put to practical use
in the internal combustion engine?
2 . Wr i t e a p a r a g r a p h e x p l a i n i n g h o w t h e p o t e n t i a l e n e r g y i n a i r c r a f t
fuels is converted into the thrust required for powered flight.

LessonXV
EXERCISE NO. 1 (You have 5 minutes to complete
this exercise.)

Place a T in the blank space which precedes a true statement;
place an F in the blank space which precedes a false statement
a ……;…. Reciprocating engines are also known as reaction
engines b. ................. The turbo-jet engine is in many respects
less complicated than a reciprocating engine.
c ……………. Most aircraft reciprocating engines are of the
"four-stroke-five-event-cycle” type.
d……………. Ignition in the combustion chamber takes place
some time after the compression stroke is started and before
the power stroke is completed.
e ................... The diesel engine shows promise as a future
aircraft engine.

f ................... The valves of a two stroke cycle engine open and close
twice as fast as they do on a four-stroke cycle engine
g…….........
Normally, in-line engines are liquid-cooled while radial engines aircooled.
h .................
Radial engines always have an odd number of cylinders in each row.
i .................
Jet propulsion is based on Newton's second and third laws of motion.
j .......... Rocket engines like the turbo-jet engines have been
developed to the point where they can be effectively used in large
bomber and transport type aircraft.

EXERCISE NO. 2
(You have 10 minutes to complete this exercise.)

Fill in the blank spaces with the word, or words, that properly complete
the statement.
a The most simple reciprocating engine consists of
……………………….., a……………………….., a
……………………………, and a ……………………………..
b. Since an aircraft engine must be of comparatively
……………………………,
little use is made of the diesel as a power plant unit for aircraft.
c. The principle advantage of jet propulsion of aircraft
is .........................
d. One type of turbo-jet engine has an ,………………………….. where
extra fuel is injected into the escaping gases, giving added
……………………..
to the engine.
e. The first jet propelled aircraft that actually flew was developed by an
…………………………
named …………………………….
f. It appears likely that reciprocating engines will be used as the
principal element of ……………………………
and ………………………………….
power plants for many years to come.
g. The …………………………………. ............ helps convert the
straight-line motion of the piston to the rotary motion of the crankshaft.
h., The five events that happen during the four-stroke cycle are
……………………………., ……………………………..,
……………………., ……………………. 4

i. A common application of jet propulsion is
the .......................................
or similar device. j.
j ……………………………………engines are easier to streamline than
engines.

EXERCISE NO. 3
(You have 5 minutes to complete this exercise.)
Draw a circle around the number preceding the phrase that makes the
statement most correct
a. The first turbo-jet power plant was designed by
1. An Italian named Campine
2. Charles Taylor
3. Air Commodore Frank Whittle
4. Robert Boyle
b. A jet engine that has a device whereby extra fuel can be injected into the
escaping gases to give added thrust is said to be equipped with a:
1. Hot pipe
3. Afterburner
2. Afterthought
4. Afterglow
c. Most air cooled engines are of the
1. In-line type
3. Four-stroke-cycle type
2. Radial type
4. None of these
d. Both the intake and the exhaust valves in a four-stroke engine are closed on
the
1. Intake stroke
3. Ignition stroke
2. Power stroke
4. Exhaust stroke. That part of the turbo-jet engine that does the same job as
the piston in a reciprocating engine is called a
1. Turbine
3. Turbo-supercharger
2. Compressor
4. None of these

EXERCISE NO. 4
(You have 15 minutes to complete this exercise.) 1. Show,
by means of a drawing, the position of the valves and the
direction of travel of the piston during each of the four
strokes of an internal combustion engine.
2. Radial engines ore usually easier to maintain than inline engines Why is this the case?
5

LessonXVI
EXERCISE NO. 1
(you have 5 minutes to complete this exercise.) Place a T in the
blank space which precedes a true statement; place an F in the
blank space which precedes a false statement.
a ……….. In order to get the proper fuel-air mixture into an
engine's combustion chamber, either a diaphragm-carburetor or
an injection-carburetor must be used to meter and atomize the
fuel and mix the fuel with air.
b ................... A float type carburetor is not affected by any
unusual change in the altitude of the aircraft as the diaphragm
type carburetor is.
c. .................. When fuel is vaporized in the carburetor it can
cause a decrease in air temperature of as much as 30° to 40° F.
d…………………… The fuel injection system eliminates
completely the problem of ice formation, since fuel vaporization
takes place at the intake valve where temperatures are normally
quite high.
e……………….. A supercharger is a part of the induction
system.
f ................... Superchargers are primarily used on aircraft
engines designed for low altitude operation.
g ……………….
A jet engine uses a diaphragm type carburetor so that it will
function properly regardless of the altitude of the aircraft.
h .............. A supercharger is a sort of air compressor.
i ……….. All superchargers operate on the same principle, i.e.
revolving blades press the air into the carburetion system and
consequently build up manifold pressure.
j…………….…. The economizer valve in a carburetor works in
cooperation with the accelerating pump.

EXERCISE NO. 2
(You have 10 minutes to complete this exercise.) Fill
in the blank spaces with the word, or words, that
properly complete the statement.
a. A carburetor is used with reciprocating type
engines that do not employ the
………………………… system.

b. The first task of a carburetor is
to ........................................................... fuel.
c. The second task of a carburetor is to ……………………………
the fuel.
d. The …………………………........... helps break the fuel into
small particles as it is discharged from the carburetor nozzle.
e. An engine driven internal supercharger located between the
carburetor and the intake manifold is called
an ......................................................
f. The ................................................
compresses the air before it reaches the carburetor.
g. …………………………………………….. is caused by
improper combustion.
h. The ............................................... ................... controls the
amount of the fuel-air mixture entering the manifold for
distribution to the cylinders.
i. An ................................................. is incorporated in the
aircraft carburetor to allow an aircraft engine the to run while the
throttle is fully closed.
j. The function of the .......................................................
is to transmit air to the carburetor and feed the resulting mixture
to the cylinders in the proper amount and at the proper pressure
and temperature.

EXERCISE NO. 3
(You have 5 minutes to complete this exercise.)
Draw a circle around the number preceding the phrase which makes
the statement most correct.
a. One of the following is not the proper nomenclature for a type of aircraft carburetor.
1. Ram air type
3. Diaphragm type 2. Fuel injection type
4. Float type
b. When compared to sea level pressure, atmospheric pressure at 15,000 feet is
1. About twice as much
3. About 15 times as much
2. About half as much
4. About the same
c. Which of the following is not a part of the carburetor
1. Venturi
3. Impeller
2. Idle air bleed
4. Discharge nozzle

d. In a turbo-supercharger the turbine wheel is driven by
1. An auxiliary motor
2. The crankshaft
3. Exhaust gases from the engine
4. Air induction motor
e. Jet engines use
1. Ram air type carburetors
2. Fuel injection systems 3. Fuel injection
type carburetors 4. Diaphragm type
carburetors

EXERCISE NO. 4
(You have 15 minutes to complete this exercise.) 1. List the
similarities and differences between a turbo-supercharger and a
turbo jet engine.
2. List the advantages of the fuel injection carburetor over the
diaphragm and flow type carburetors. What is the main
disadvantage of the injection type carburetor?
3. Draw schematically the induction system of a large aircraft
engine.
Show the location of such parts of the system as internal
supercharger, turbo supercharger, carburetor and intake manifold.

LessonXVll
EXERCISE NO. 1
(You have 5 minutes to complete this exercise.) Place a T
in the blank space which precedes a true statement; place
an F in the blank space which precedes a false statement.
a ................... If a magnetic field is moved across a
conductor, the effect is the same as that which occurs
when the conductor is moved through the magnetic field.
b ………………. Ignition systems are of two types:
generator and magneto.
c………………… The purpose of a condenser in an
ignition system is to reduce the electricity at the distributor.
d. .................. Direct electric starting is the most widely
used of all starting systems.
8

e ................... An electric motor is a generator operating in reverse.
f ………………..
Aircraft using magnetos for ignition usually use the magneto as a
source of electricity to operate other aircraft systems.
g .................
The ignition system of the jet engine is much less complicated than
that of the reciprocating engine.
h ……………… A booster co is used to build up the voltage for the
"spark-jump" when the engine is turning at take-off RPM.
i ................
An induction (secondary) coil is used with each spark plug to obtain
voltage needed for the "spark-jump" when low tension magnetos are
used.
j ………………….. A condenser does not provide a path for the
transmission of an electrical current.
EXERCISE NO. 2 (You have 10 minutes to complete this
exercise.)

Fill in the blank spaces with the word, or words, that properly
complete the statement.
a. One type of magneto, the ……………………………………..
does not "step up" the voltage of the primary circuit.
b. Electric starters use an electric motor whose source of
electricity is produced by the ………………………. and stored in
an electric ..................................................
c. When a conductor of electricity is moved through a magnetic
field a current will flow through the …………………………………..
d. The …………………………… is a revolving contact point which
posses over a circle of other stationary contact points.
e. An induction coil of a magneto is really a
……………………………….
that steps up the voltage.
f. if a primary coil which has 50 turns of wire produces 24 volts, its
secondary coil which has 500 turns will produce
……………………………. volts.
g. The magneto is a special kind
of ........................................................
h. In inertia starting the crank turns
a ................................................
, which in turn rotates the crankshaft through a clutch
arrangement.

i. A current flowing through a conductor sets up a
…………………………………………… around the conductor.
j. In an aircraft magneto, magnets are rotated between "pole shoes" by means
of on accessory shaft geared to the ……………………………………..

EXERCISE NO. 3 (You have 5 minutes to
complete this exercise.)
Draw a circle around the number preceding the phrase which makes
the statement most correct.

a. The voltage produced by the average aircraft magneto is
1. 20 volts
3. 2000 volts 2. 200 volts
4. 20,000 volts
b. The most widely used starting system for aircraft is the
1. "Spinning the prop by hand" system
2. Electric inertia starting system
3. Direct electric starting system
4. Hand crank inertia starting system
c. One of the following is not considered a part of an aircraft magneto ignition
system.
1. Distributor
3. Battery
2. Condenser
4. Spark plug
d. The ignition system found on most modern aircraft is the
1. Dual magneto type
3. Single battery type
2. Single magneto type
4. Dual battery type
e. One of the following is not used to increase the voltage in the ignition
system
I. Condenser
3. Booster coil
2. Magneto
4. Distributor

LessonXVlII
EXERCISE NO. 1 (You have 5 minutes to complete
this exercise.)

Place a T in the blank space which precedes a true statement; place
an F in the blank space which precedes a false statement.
a. ..................The principle of operation of the aircraft engine is
based upon the fact that heat energy can be changed into
mechanical energy.
b ................... The first law of thermodynamics states that although
energy may change its form, no energy is destroyed except that lost
through friction.
c ...................
In measuring units of work, the British Thermal Unit (BTU) is used.
d ..................
Mechanical efficiency is the ratio of brake horsepower to indicated
horsepower.
e ………….. In calculating the indicated horsepower of an engine, the
horsepower produced varies directly with the length of the stroke.
f ……………….. About 20% of the heat produced in an aircraft
combustion chamber is carried away by the exhaust.
g ………………
If a jet propelled airplane was flown in a vacuum its forward velocity
would equal the velocity of the jet its engine produced.
h ……………… Crude petroleum is the source of modern aviation
fuels.
i …………… In reciprocating engines, the more rapid the fuel vapor
burns, the greater power the engine will produce.
j ………………….
The ability of an engine fuel to turn into vapor is called its fractional
distillation index.

EXERCISE NO. 2 (You have 70 minutes to complete this
exercise.)

EXERCISE NO. 4
(You have 15 minutes to complete this exercise.) 1. Draw
schematically an aircraft ignition system depicting the essential
parts of the system.
2. List the four most commonly used starter systems for modern
aircraft.
10

Fill in the blank spaces with the word, or words, that properly
complete the statement.
a. The …………………………………. is an index to the slowburning quality of the fuel.

b. An English physicist named ...............................
demonstrated many years ago that it was possible to transform a
certain amount of work into the same amount of heat.
c. If all the heat energy in one BTU could be salvaged, it would
produce ………………………………..
ft./lbs, of work.
d. About …………………..
of the total heat produced by the reciprocating engine is expended
because of friction.
e. One pound of gasoline has a potential heat energy content of
…………………………… BTU.
f. Indicated horsepower minus brake horsepower equals
…………………………….
horsepower.
g. One horsepower is equal to ...............................................
ft./lbs, per minute.
h. The letters m.e.p, in thermodynamics stand for
………………………………..
i. The jet engine's rate of fuel consumption is .............................
compared to a reciprocating engine.
j. Too rapid burning of fuel vapors in the combustion chamber
causes ....................................................... or a sudden rise
followed by a rapid decrease in pressure.

c. One pound of thrust of a jet engine will equal two horsepower when the
speed of the jet aircraft is:
2. 250 MPH
3. 500 MPH
2. 375 MPH
4. 750 MPH
d. In calibrating the indicated horsepower of a four-stroke-cycle engine we can
arrive at the number of pressure strokes per minute by dividing the RPM of the
engine by:
1. 2
3. 4
2. 3
4. 8
e. A British Thermal Unit is:
1. The amount of heat necessary to raise I cc of water 1 o C.
2. The amount of heat necessary to raise 1 ounce of water 1 o F.
3. The amount of heat necessary to raise 1 pound of water 1 o C.
4. The amount of heat necessary to raise 1 pound of water 1 o F.

EXERCISE NO. 4
(You have 15 minutes to complete this exercise.)
1. Which engine, the reciprocating or the jet, has the least thermal
efficiency. Why?
2. An afterburner on a jet increases the power output of the engine.
W h a t e ff e c t d o e s t h e a f t e r b u r n e r h a v e o n t h e t h e r m a l e f fi c i e n c y o f t h e
engine.

EXERCISE NO. 3
(You have 5 minutes to complete this exercise.)
Draw a circle around the number preceding the phrase which
makes the statement most correct.
a. The fuel-air mixture in a reciprocating engine combustion
chamber burns at about:
1. 200° Centigrade
3. 2000° Fahrenheit
2. 200° Fahrenheit
4. 2000° Centigrade
b. The thermal efficiency of an aircraft reciprocating engine runs
about:
1. 100%
3. 50%
2. 75%
4. "25 %
12

LessonXIX
EXERCISE NO. 1 (You have,5 minutes to complete this
exercise.)

Place a T in the blank space which precedes a true statement;
place an F in the blank space which precedes a false statement.
a …………….. Friction generates heat.
b ……………..Petroleum is a member of the hydrocarbon family.
c. ..................The lower the viscosity of an oil, the greater the
weight it can support without breaking.
d. .................. All crude oils (petroleum) are asphalt base.

e..................
Oil gets its lubricating ability from the fact that its molecules are
greasier than the molecules of other substances except pure
grease.
f ................. In air cooled engines cowl flaps are used to scoop
up the air that is used to cool the engines.
g ...... ........... In liquid cooled engines the oil in the lubrication
system acts as the coolant in the cooling system
h. Jet engines are liquid cooled
i …………….. Wet sump lubricating systems are usually found
on large engines.
j ................... One way to help keep cylinder head temperatures
down is to use a greater ratio of fuel to air in the combustion
chamber.

EXERCISE NO. 2 (You have 10 minutes to
complete this exercise.)
Fill in the blank spaces with the word, or words, that properly complete the
statement.
a. Oil, when placed between moving parts, tends to form a layer only one
molecule deep; this is known as a ………………………………..
………………….. layer.
b. An index to an oil's ability to flow at certain temperatures is
…………………………..………..
c. The .................................................
test discovers the temperature at which an oil gives off inflammable vapor.
d. The ……………………………………
forces the oil of an aircraft engine oil system from the sump through a filter, a
radiator and back into the storage tank.
e. The ........................................ is used to feed the oil through oil lines to the
engine parts.
f. Two systems of engine cooling are used in aircraft engines. They are the
……………………………….
system and the ...................................
system.
g. Heat has been defined as the motion of the
………………………………………. of a substance.
h. As a result of compression and ignition, cylinder head temperatures of an
uncooled aircraft engine could reach ……………………………………….
degrees F.
14

i. Radial engines are usually ……………………………………… cooled.
j. ............................................ are used to control the amount of air that
flows around an air cooled aircraft engine.

EXERCISE NO. 3 (You have 5 minutes to complete
this exercise.)

Draw a circle around the number preceding the phrase which makes
the statement most correct.

a The best lubricating oil for aircraft engines is." 1. Animal oil
3. Mineral oil 2. Vegetable oil
4. Wesson oil

b. One of the tests not used to determine the characteristics of lubricating oil is the
1. Viscosity test
3. Flash point
2.
Octane rating test
4. Sulphur content test
c. Indicate which of the following statements is false.
1.
Friction between two metal parts is less when the parts in contact are of different
metals.
2. Petroleum is a member of the great hydrocarbon family.
3.
Oil of the oil system carries off a great amount of excess engine heat.
4.
In-line engines are more difficult to streamline because they are usually liquid cooled
engines and carry radiators and coolant pumps not found on radial engines.

d. The S.A.E. have established viscosity ratings for lubricating oils.
S.A.E. stands for
1. Society of Aeronautical Engineers
2. Society of Automotive Engineers
3. Sigma Alpha Epsilon
4. Society of American Engineers
e. The oil system consists of an oil storage tank, an oil pump, oil lines, a sump and scavenger pump, an
oil filter and a
1. Coolant
3. Distributor
2. Radiator
4. Manifold

EXERCISE NO. 4
(You have 15 minutes to complete this exercise.) 1. Discuss the
three methods of reducing friction between moving parts.
Give an example in the aircraft engine of how the three
methods are used in combination.
2. Make a schematic sketch of an aircraft engine oil system
showing its various component ports.

LessonXX
EXERCISE NO. 1
(You have 5 minutes to complete this exercise.)
Place a T in the blank space which precedes a true statement;
place an F in the blank space which precedes a false statement.
a................. To develop power and to convert it into thrust are
the major purposes of the aircraft power plant The aircraft
propeller virtually succeeds in combining these two tasks into
one.
b. .................. The blade of a propeller is a type of airfoil just as
the aircraft win is an airfoil.
c ................... The principle of propeller action is based on the
fact that a decrease in pressure in any direction will cause the
air to produce a force in that direction.
d............... All wood propellers are fixed-pitch and all metal
propellers are variable-pitch propellers.
e………………..
An adjustable propeller can be adjusted by the pilot in flight.
f. ..................
Reversible pitch propellers are used to reverse the direction of
rotation of the propeller.
g ................. In flight the propeller tip travels faster than the
propeller hub...
h ................
The electric propeller uses an electric motor to govern propeller
speed.
i. …………………. Blade pitch is defined as the angle made by
the chord of the blade element and the plane in which the
propeller rotates.
j................. The fixed pitch propeller is a compromise, its pitch
setting is neither the best possible for take-off nor for cruising.
16

EXERCISE NO. 2 (You have 10 minutes to
complete this exercise.)
Fill in the blank spaces with the word, or words, that properly complete
the statement.

a. Like the rotor of a helicopter, the propeller, in a sense, is a
…………………………………………….
b. In flight the propeller has two motions, ………………………………….
and ………………………….,
the path of this motion is .................................. (shaped like a
corkscrew).

c. One classification of propeller is based upon whether the pitch of
the propeller blade is .......................... or ....................................
d. There are two types of variable-pitch
propellers; ......................................
and ..............................................
e. Constant-speed propellers are of two principal types, depending
upon the system controlling their operation. One type uses
a ........................... system; the other, an …………………………….. system.
f. Both types of constant-speed propellers use a ............................................
as the core of the automatic pitch control.

g. Some propellers are dual rotating, they are called ..................................
propellers.

h. Propellers that are so constructed that the pilot can change the blade angle
to create a backward thrust are called ......................................
propellers.

i. The governor of a hydraulic propeller activates a control rod that opens
and closes a ………………………………… and also operates
an ........................................
which in turn varies the oil pressure on either side of a ..................................
in the dome section of the propeller assembly.

i. The governor of an electric propeller, through the control rod, opens or closes an
electric switch to a ………………………………….. in the propeller hub.

EXERCISE NO. 3
(You have 5 minutes to complete this exercise) Draw a circle
around the number preceding the phrase which makes the
statement most correct.
a. Reduction gears are used in propeller systems, particularly on
propellers with large diameters to:
1. Reduce wear on the system.
2. Keep propeller tip speed below the speed of sound.
3. Help keep the engine cool.
4. Feather the propeller on "dead" engines.
b. Propellers are feathered to:
1. Help brake the airplane and thereby shorten the landing run.
2. Reduce drag and eliminate windmilling on dead engines.
3. Get more engine power for take-off.
4. Utilize less gas during normal cruise operations.
c. One type of variable pitch propeller is little better than a fixedpitch one, it is the:
1. Electric propeller
3. Adjustable propeller 2. Hydraulic propeller
4. Controllable propeller
d. Regardless of the length of a propeller blade the speed of the
propeller tip, in relation to a section midway between the hub
and tip, will travel:
1. At at rate equal to the mid-section
2. At a rate equal to 2 times the rate of the mid-section
3. At a rate one-half times the mid-section
4. At a rate twice that of the mid-section
e. There is a certain similarity between three of the following
from the standpoint of function and design. Which one is the
dissimilar one? 1. Aircraft propeller
3. Helicopter rotor 2. Aircraft wing
4. Aircraft tail section

EXERCISE NO. 4
(You have 15 minutes to complete this exercise.) 1. Make a
simple diagram of the major parts of a hydraulic propeller
control system.
2. Explain why a propeller blade is designed in such a way
that the camber, chord, and pitch is different for each section.
18

LessonXXI
EXERCISE NO. 1 (You have 5 minutes to complete this
exercise.)

Place a T in the blank space which precedes a true statement;
place an F in the blank space which precedes a false statement.
a................
Engine designers have been able to reduce the number of
engine instruments required for modern aircraft engines under
that required by earlier engines.
b ……………..
The purpose of the engine instruments is to keep the pilot
informed of the operating conditions of his engine.
c ................... Most aircraft engine pressure gauges are of the
vapor-pressure, thermometer type.
d. ………….. The tachometer on engines equipped with fixed
pitch propellers gives an indication of the engine power output.
e ................... The vapor-pressure type, temperature indicator
uses a bulb containing a highly volatile liquid.
f ................... Electronic mechanisms ore electric devices which
employ vacuum tubes.
g................ Jet engine controls are much more complicated than
reciprocating engine controls.
h ................... It is by means of the mixture control that a proper
ratio of fuel to air is kept in the induction system.
All engine control systems operate on the "push-pull tube
control" system.
Where automatic controls are used, some method of manual
control is almost always kept as a safeguard in the event of
failure of the automatic system.

EXERCISE NO. 2 (You have 10 minutes to complete
this exercise.)

Fill in the blank spaces with the word, or words, that properly complete the
statement.
a. Pressure gauges operate either on
the ............................................................... principle or
the .................................................... prlnciple.

b. Temperature indicators may employ the principle of the
………………………………….., the .....
............................................., or the vapor-pressure type thermometer
and Bourdon tube.
c. On large multi-engine aircraft where considerable distances
separate the point where a measurement is to be made, and the
instrument panel where the reading is
taken .......................................................................................
systems are in common use.
d. The vapor-pressure type temperature indicator uses a
……………………………….. containing a highly volatile liquid such as
methyl chloride, a ………………………….
tube and a Bourdon tube.
e. The principles underlying, the operation of automatic controls are
………………………………………,
............................................... or electronic.
f. The control .................................................
is a frame secured to the floor of the cockpit which supports the
control quadrants and control mechanisms.
g. An automatic mixture control lever has four positions. They are
………………………, ………………………., …………………….., and
………………………
h. A manually operated mixture control has
any .............................................
positions.
i. In terms of operating method, there are three classifications of
engine controls: the ..................................., the
…………………………………………,
and the automatic.
j. In terms of construction there are two engine control systems: the
…………………………………………………………………….. and
the .......................................................

EXERCISE NO. 3
(You have 5 minutes to complete this exercise.) Draw a circle
around the number preceding the phrase which makes the
statement most correct.
a. One of the following is not normally used as an aircraft engine
instrument.
1. Oil pressure gauge
2. Fuel pressure gauge
3. Manifold pressure gauge
4. Cylinder head pressure gauge
20

b. Temperature gauges for aircraft instruments are usually one of three
types. Which one of the following is not used to measure temperature?
1. Wheatstone bridge
2. Thermocouple
3 Vapor-pressure type thermometer and Bourdon tube
4. Aneroid
c. One of the most important controls, the one that helps the pilot
govern the power output of the engine and the speed of the airplone, is
the:
1. Mixture control
3. Propeller control
2. Throttle
4. Quadrant
d. Which of the following engine instruments would you expect to find
on an in-line engine but not on a radial engine?
1. Cylinder head temperature gauge
2. Manifold pressure gauge
3. Coolant temperature gauge
4. Carburetor air temperature gauge
e. On the control quadrant of airplanes equipped with reciprocating
engines are usually found levers marked "P', "T', and "M". These
letters stand for
1. Propeller, throttle, and magneto
2. Propeller, turbo-supercharger, and mixture
3. Power, throttle, and magneto
4. Propeller, throttle, and mixture

EXERCISE NO. 4
At this point, if you should have any questions about the material covered in the
previous seven classes, bring these to the attention of the instructor. This period
should be devoted to discussing all questions which you and other students desire to
have answered.