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Regional Gliding School

The Propeller• The function of the propeller is to

convert the torque, or turning movement, of the crankshaft into thrust, or forward, speed.

• Designed that, as it rotates, it moves forward along a corkscrew or helical path.

• It pushes air backward with the objective of causing a reaction, or thrust, in the forward direction.


The Propeller• The jet engine moves a small

mass of air backward at a relatively high speed.

• The propeller, on the other hand, moves a large mass of air backward at a relatively slow speed.

• The propeller blade is an airfoil section, similar to the airfoil section of a wing.


The Propeller• It meets the air at an angle

of attack as it rotates.

• It produces lift and drag.

• In the case of the propeller, the forces are designated as thrust and torque.


The Propeller• Those attached forward of

the engine and pull are called tractors.

• Those which are attached aft of the engine and push from behind are called pushers.


Pitch The distance in feet a propeller travels

forward in one revolution. The angle at which the blade is set governs

the pitch. There is a Coarse Pitch meaning the blade

is set at a larger angle. There is a Fine Pitch meaning the blade is

set at a small angle.


Coarse Pitch Travels forward a greater distance with

each revolution. The airplane will move forward at greater

speed for a given RPM. Like high gear in a car. Best suited for high speed cruise and for

high altitude flight.


Fine Pitch Less torque, or drag. Revolves at a higher speed around its own

axis. Enables the engine to develop greater

power. Like low gear in a car. Gives best performance during take-off

and climb.


Types of Propellers Fixed Pitch:

constant blade angle, blades are at an angle in

between fine and course pitch to give the best overall performance possible for all flight conditions.

Controllable Pitch: blade angle can be adjusted

by the pilot to various angles during flight.

Adjustable Pitch: blade angle may be

adjusted on the ground.

Constant Speed: blades automatically adjust

themselves to maintain a constant RPM as set by the pilot.


• Propeller Control Systems: the mechanism for varying the pitch of the propeller

may be: mechanical - hand controlled by linkages hydraulic - a fluid under pressure pushes or pulls on a cam

that uses gears to turn the blades of the propellers

electrical - operated by an electric motor.

• Feathering: turning the propeller blades to an extreme coarse

pitch, used in the event of an engine failure to stop the

propeller from “wind milling”. It will reduce drag of the failed engine or propeller.


• Thrust Reversing:

changing the pitch below the idle position (full fine pitch) into the reverse range or negative pitch,

thrust now works in the reverse direction,

used to slow down the aircraft after it has landed and to manoeuvre the aircraft on the ground.

Confirmation Stage

NOTE: You must use the buttons in the Confirmation Stage


Aero EnginesAero EnginesThe Propeller and Engine InstrumentsThe Propeller and Engine Instruments

A

B

C

D

Adjustable

Fine

Constant

Let's try a few review questions on Aero Engines:

Question #1 - Name a type of pitch?

Mechanical

I’m afraid that answer is incorrect

Let's try again...

Flying Scholarship Program


That answer is correct.

Let's move on...

Regional Gliding School (Atlantic)

Pitch The distance in feet a propeller travels

forward in one revolution.

The angle at which the blade is set governsthe pitch.

There is a coarse pitch meaning the bladeis set at a larger angle.

There is a fine pitch meaning the blade isset at a small angle.


A

B

C

D

Air braking

Thrust reversing

Hydraulic positioning


Question #2 - Changing the pitch below the idle position (full fine pitch) into negative pitch is known as what?

Feathering



Let's try again...




Let's move on...


• Thrust Reversing:

changing the pitch past the featheringposition,

thrust now works in the reversedirection,

used to slow down the aircraft after ithas landed and to manoeuvre the aircrafton the ground.


Basic Engine Instruments

Although an aircraft has many complex instruments, the basic engine instruments are perhaps the most important.

These gauges monitor essential components of the engine.

Can indicate early warning signs of potential problems and possible engine failure.


Colour CodingColour code ranges from green, to yellow to red, indicating normal, caution and danger operating settings respectively.


Oil Pressure Gauge Monitors oil pressure

supplied by oil pump.

High pressure can force oil into the combustion chamber where it will burn.

Low pressure leads to poor lubrication.


Oil Temperature Gauge

Monitors temperature of oil.


Carburetor Air Temperature Gauge

Enables pilot to monitor the temperature of intake air or air/fuel mixture into the carburetor.

If icing exists, the carburetor heat control unit can be activated by the pilot.


Tachometer (RPM Indicator)

Monitors the number of revolutions per minute the engine crankshaft is turning.

On aircraft with fixed or controlled pitch propellers, RPM is controlled by the throttle.


Cylinder HeadTemperature Gauge

Records the temperature of one or more of the engine cylinder heads.

Extremely high cylinder head temperatures are immediate signs of engine overloading.


Manifold Pressure Gauge

Usually located beside the tachometer because both indicate engine power output.

A drop in manifold pressure usually indicates carburetor icing.

Confirmation Stage

NOTE: You must use the buttons in the Confirmation Stage


A

B

C

D

Camshaft revolutions

Engine power control

All the above


Question #3 - What does the tachometer monitor?

Crankshaft revolutions



Let's try again...




Let's move on...


Tachometer (RPMIndicator)

Monitors the number ofrevolutions per minutethe engine crankshaft isturning.

On aircraft with fixed orcontrolled pitchpropellers, RPM iscontrolled by thethrottle.


A

B

C

D

Cylinder Head Temperature Gauge

Manifold Pressure Gauge

Both A and C


Question #4 - What instrument indicates engine power output?

Tachometer



Let's try again...




Let's move on...


Manifold PressureGauge

Usually located beside thetachometer because bothindicate engine poweroutput.

A drop in manifoldpressure usually indicatescarburetor icing.


Congratulations!!

You have now completed the Propeller and Engine Instruments lesson of the Aero Engines Module. Of course, this lesson is always available to you for future reference if required.

You are now ready to move along to the next module you have not completed or to any other module you wish. You can advance to the Self Test Module if you feel ready to challenge the final exam.

Good Luck!


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Documents

propeller blades

adjustable pitch

controllable pitch

course pitch

negative pitch

type of pitch

propeller travels

constant blade angle