Engines Flashcards
What is the main function of an aircraft engine?
To create the necessary movement for an aircraft and to provide hydraulic and electric power plus bleed air for the pneumatic system
What are the two types of engine?
-piston type
-gas turbine
What are the 4 types of gas turbine engines?
-turbojet
-turboprop
-turbofan
-turbo shaft
What wash the first type of engine ever used?
Turbojet
When does a turbojet engine experience issues and with what?
Issues with noise and fuel consumption at 0.8 mach
what are some advantages of a turbojet engine?
-relatively simple design
-capable of very high speeds
-takes up little space
What are some disadvantages of a turbojet engine?
-high fuel consumption
-loud
-poor performance @ slow speeds
-limited in range & performance
What was the turbofan engine developed from?
The turbojet engine
Why is the turbofan arrangement better?
Because of high aircraft speeds with food fuel efficiency
What are the two turbofan arrangements?
-twin spool
-triple spool
Define a spool?
A turbine driving a compressor through a shaft
Describe a twin spool?
High pressure turbine driving a high pressure compressor and a low pressure turbine driving a low pressure compressor
What does a triple spool add?
An intermediate turbine with and intermediate compressor
What are the advantages of a turbofan?
-fuel efficient
-quieter than turbojets
-streamline appearance
What are the disadvantages of a turbofan?
-heavier than turbojets
-larger frontal area than turbojets
-inefficient at very high altitudes
What are turboprop engines designed to do?
Produce shaft horsepower only to drive a propeller
What are the principles of a turboprop engine similar to and what is the difference?
Turbojet principles only difference is additional turbines,a power shaft and reduction gearbox are added
What are the advantages of turboprop engines?
-very fuel efficient
-most efficient at 250-400 knots
-most efficient at 18k-30k ft
When is a turboprop most efficient? (Mid,low,high range)
Mid range
What are the disadvantages of a turboprop engine?
-limited forward airspeed
-gearing systems are heavy & can break down
What does a turboshaft engine prioritise?
Shaft power to drive machinery rather than thrust
Describe a turboshaft engine briefly?
Small but powerful lightweight engine
What is a turboshaft engine usually called?
An APU
What does a turboshaft engine do for the aircraft?
Supplies electric & pneumatic power when engines not available
Where is a turboshaft engine used outside of planes?
Helicopters
What are the advantages of a turboshaft engine?
-much higher power to weight ratio than piston engines
-typically smaller than piston engines
What are the disadvantages of a turboshaft engine?
-loud
-gear systems connected to the shaft can be complex and break down
Where does intake,compression,combustion and exhaust occur on a reciprocating engine?
In the same combustion chamber
Name some things a typical gas turbine engine consists of?
-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)
What are the two section types in a gas turbine engine and what are they?
-hot (compressor to combustion chambers & exhaust)
-cold (inlets to compressors/diffusers)
What are some advantages to the engine manufacturer for modular design?
-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
What are the advantages of modular design for the engine operator?
-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
What is the main requirements for engine materials?
-it’s have strength for required purposes
-must be as light & cheap as possible
Name some typical engine materials?
-aluminium alloy
-ceramic material
-composite material
-cobalt base alloy
-nickel base alloy
-corrosion resistant steel alloy
-titanium base alloy
