Engines

Question 1

What is the main function of an aircraft engine?

Answer 1

To create the necessary movement for an aircraft and to provide hydraulic and electric power plus bleed air for the pneumatic system

Question 2

What are the two types of engine?

Answer 2

-piston type
-gas turbine

Question 3

What are the 4 types of gas turbine engines?

Answer 3

-turbojet
-turboprop
-turbofan
-turbo shaft

Question 4

What wash the first type of engine ever used?

Answer 4

Turbojet

Question 5

When does a turbojet engine experience issues and with what?

Answer 5

Issues with noise and fuel consumption at 0.8 mach

Question 6

what are some advantages of a turbojet engine?

Answer 6

-relatively simple design
-capable of very high speeds
-takes up little space

Question 7

What are some disadvantages of a turbojet engine?

Answer 7

-high fuel consumption
-loud
-poor performance @ slow speeds
-limited in range & performance

Question 8

What was the turbofan engine developed from?

Answer 8

The turbojet engine

Question 9

Why is the turbofan arrangement better?

Answer 9

Because of high aircraft speeds with food fuel efficiency

Question 10

What are the two turbofan arrangements?

Answer 10

-twin spool
-triple spool

Question 11

Define a spool?

Answer 11

A turbine driving a compressor through a shaft

Question 12

Describe a twin spool?

Answer 12

High pressure turbine driving a high pressure compressor and a low pressure turbine driving a low pressure compressor

Question 13

What does a triple spool add?

Answer 13

An intermediate turbine with and intermediate compressor

Question 14

What are the advantages of a turbofan?

Answer 14

-fuel efficient
-quieter than turbojets
-streamline appearance

Question 15

What are the disadvantages of a turbofan?

Answer 15

-heavier than turbojets
-larger frontal area than turbojets
-inefficient at very high altitudes

Question 16

What are turboprop engines designed to do?

Answer 16

Produce shaft horsepower only to drive a propeller

Question 17

What are the principles of a turboprop engine similar to and what is the difference?

Answer 17

Turbojet principles only difference is additional turbines,a power shaft and reduction gearbox are added

Question 18

What are the advantages of turboprop engines?

Answer 18

-very fuel efficient
-most efficient at 250-400 knots
-most efficient at 18k-30k ft

Question 19

When is a turboprop most efficient? (Mid,low,high range)

Answer 19

Mid range

Question 20

What are the disadvantages of a turboprop engine?

Answer 20

-limited forward airspeed
-gearing systems are heavy & can break down

Question 21

What does a turboshaft engine prioritise?

Answer 21

Shaft power to drive machinery rather than thrust

Question 22

Describe a turboshaft engine briefly?

Answer 22

Small but powerful lightweight engine

Question 23

What is a turboshaft engine usually called?

Answer 23

An APU

Question 24

What does a turboshaft engine do for the aircraft?

Answer 24

Supplies electric & pneumatic power when engines not available

Question 25

Where is a turboshaft engine used outside of planes?

Answer 25

Helicopters

Question 26

What are the advantages of a turboshaft engine?

Answer 26

-much higher power to weight ratio than piston engines -typically smaller than piston engines

Question 27

What are the disadvantages of a turboshaft engine?

Answer 27

-loud -gear systems connected to the shaft can be complex and break down

Question 28

Where does intake,compression,combustion and exhaust occur on a reciprocating engine?

Answer 28

In the same combustion chamber

Question 29

Name some things a typical gas turbine engine consists of?

Answer 29

-an air inlet (fan blades) -compressor section (low pressure compressor LPC and high pressure compressor HPC) -combustion section (diffuser & combustor) -turbine section (low pressure turbine LPT and high pressure turbine HPT) -exhaust section (turbine exhaust case TEC) -accessory section (main gearbox)

Question 30

What are the two section types in a gas turbine engine and what are they?

Answer 30

-hot (compressor to combustion chambers & exhaust) -cold (inlets to compressors/diffusers)

Question 31

What are some advantages to the engine manufacturer for modular design?

Answer 31

-rotating module parts can be pre-balanced -fewer spare engines are needed in stock -more flexibility for changes to be made to a part -main engine modules can be easily stored and transported

Question 32

What are the advantages of modular design for the engine operator?

Answer 32

-modules can be removed and replaced without disturbing the rest of the system too much -no re-balancing it required after a module change -most modules can be replaced whilst the engine remains in the aircraft -less need for spare parts and the modules can be easily transported

Question 33

What is the main requirements for engine materials?

Answer 33

-it’s have strength for required purposes -must be as light & cheap as possible

Question 34

Name some typical engine materials?

Answer 34

-aluminium alloy -ceramic material -composite material -cobalt base alloy -nickel base alloy -corrosion resistant steel alloy -titanium base alloy