Aircraft Engines

Question 1

What are the three important differences between aircraft piston and automobile engines?

Answer 1

Air cooling
Dual Ignition
Fuel/Air Miture Control

Question 2

What are the ‘Four Strokes’ of a piston engine?

Answer 2

Induction
Compression
Power
Exhaust

Question 3

What are the ‘Five Events’ associated with a Piston Engine?

Answer 3

Induction
Compression
Ignition
Power
Exhaust

Question 4

What is the Carburetor?

Answer 4

A device which provides a suitable mixture of fuel and air to the cylinder for ignition.

Question 5

How does air draw fuel through the carburetor?

Answer 5

Air flowing through the carburetor draws fuel from a reservoir through a ‘Venturi’ Tube.

Question 6

What three things happen when air passes through a Venturi in a piston engine?

Answer 6

The Air Accelerates
There is a drop in pressure
This causes fuel to be drawn through the main jet, allowing it to mix with the air in the Venturi

Question 7

What is a problem with Venturi type carburetors?

Answer 7

They are prone to Icing.

Question 8

Outline two reasons for Carb Icing.

Answer 8

The pressure drop in the Venturi is accompanied by an instant drop in temperature.

When fuel changes state from liquid to vapour, latent head is absorbed, cooling the air further.

Question 9

How much can the temperature in a carburetor drop?

Answer 9

As a result of the ‘double cooling’ effect, the air temperature in the carburetor may drop by as much as 20 degrees.

Question 10

If there is more water vapour present in the air, will the risk of carb icing be greater or lesser?

Answer 10

Greater

Question 11

How can pilots avoid carb heating?

Answer 11

Avoid areas where moisture is present and icing likely.

Regular application of carb heat.

Question 12

What system is used to overcome problems associated with carb icing?

Answer 12

Fuel Injection Systems

Question 13

Why are most aircraft piston engines air cooled?

Answer 13

Lighter and Safer

Question 14

What is the difference between geometric and effective pitch known as?

Answer 14

Slip

Question 15

Define blade pitch

Answer 15

The angle made by the chord of the blade and its plane of rotation

Question 16

What is the difference between Coarse pitch and Fine pitch?

Answer 16

A coarse pitch will take a bigger bite of air and move the aircraft farther forward in one rotation than a fine pitch.

Question 17

Which propeller pitch do you want at takeoff and cruise?

Answer 17

Takeoff - Fine
Cruise - Coarse

Question 18

What are the three types of fixed pitch propeller?

Answer 18

Coarse
Fine
Standard

Question 19

What pitch propeller do most light aircraft use?

Answer 19

Standard pitch propeller

Question 20

How is a variable pitch propeller useful if the engine shuts down?

Answer 20

Variable pitch propellers can be rotated to be parallel to the airflow and reduce drag. This is known as Feathering.

Question 21

What is another name for variable pitch propeller?

Answer 21

Constant Speed Propeller

Question 22

What are the advantages of a piston/propeller?

Answer 22

Simpler design reducing costs

More efficient at low speeds and low altitudes

Faster initial acceleration than jet engine

Immediate reaction to pilot input

Propwash over wings generates lift and aids controllability

Question 23

What is a disadvantage of a piston/propeller?

Answer 23

As the propeller tips approach supersonic speeds, their aerodynamic efficiency decreases.

Question 24

What is Newtons 2nd Law?

Answer 24

F = MA

Question 25

What are the basic parts of the jet engine?

Answer 25

Air Intake
Compressor
Combustion
Turbine
Exhaust

Question 26

What are some different types of Jet Engine?

Answer 26

Turbojet
High/Low Bypass Turbofan
Turboprop
Ramjet
Scramjet
Turboshaft (Helicopters)

Question 27

What are the two types of basic jet engine?

Answer 27

Centrifugal Compressor
Axial Compressor