5 Aircraft Systems I Flashcards
Engines provide ____ to overcome DRAG.
THRUST
Piston engines run through the ___ cycle.
OTTO
Gas turbine engines run through the ______ cycle.
BRAYTON
Describe the parts in a standard piston engine cycle.
Inlet Valve Piston Crankshaft Connecting Rod Spark Plug Outlet Valve
Describe the 4 stages of the piston (Otto) cycle.
Induction - Air drawn into cylinder through inlet valve.
Compression - Upward movement of piston compresses air.
Power - Spark used to ignite air/fuel mixture driving piston.
Exhaust - Hot gases expelled through outlet valve.
List the 5 different cylinder layouts
In-line Inverted Flat Opposed V Radial
2 main limitations of a piston engine
RPM
Temperature
List the types of gas turbines
Turbojet
Turbofan
Turboprop
Turboshaft
Describe the gas turbine work ‘cycle’
Intake - Air drawn into compressor
Compression - Inc T+P, dec Vol.
Combustion - Fuel injected and burned. Inc T+Vol.
Turbine - Work taken out of combustion gases to drive compressor.
Exhaust - Expelled from rear of turbine (possibly giving thrust).
List the sections in a Gas Turbine
Air Inlet Compression Combustion Chamber Turbine Exhaust
What sections make up the ‘Cold Section’ of a Gas Turbine?
Air Inlet
Compression
What sections make up the ‘Hot Section’ of a Gas Turbine?
Combustion Chamber
Turbine
Exhaust
In a turbojet, what proportion of the air goes into the combustion process?
100%
In an ‘optimal’ gas turbine the exhaust pressure is as close to ____ ______ to maximise energy efficiency.
INLET PRESSURE
Name the 2 types of air intake
Sub-sonic
Super-sonic
Name the 2 types of compressors
Axial
Centrifugal
Which type of compressor is “cheaper to produce”?
Centrifugal
Which type of compressor is “more difficult to manufacture”?
Axial
Which type of compressor has “lower maintenance and running costs”?
Centrifugal
Which type of compressor has “small mass flow rates”?
Centrifugal
Which type of compressor has a “large frontal area”?
Centrifugal
Which type of compressor has a “low compression ratio”?
Centrifugal
Which type of compressor has “higher maintenance and running costs”?
Axial
Which type of compressor is “multi stage”?
Axial
Which type of compressor has “air flowing radially”?
Centrifugal
Which type of compressor is “more expensive to produce”?
Axial
Which type of compressor is “single stage”?
Centrifugal
Which type of compressor has a “small frontal area”?
Axial
Which type of compressor has a “high compression ratio”?
Axial
Which type of compressor has “large mass flow rates”?
Axial
List the types of Combustion Chambers.
Multiple
Can-Annular
Annular
What is Turbine Creep?
Turbine blades lengthen under load and high temps.
What is Thermal Stress?
Rapid changes in temp causes uneven expansion and contraction in a turbine blade which increases the stress in the blade.
Advantage of a Turbofan
Increased thrust at low speeds results in better take-off performance.
Describe a Turbofan
Most common derivative of gas turbine
Has “By-pass”
In a Turboprop. The _____ absorbs the majority of the gas energy to drive the propeller
TURBINE
Advantage of a Turboprop
Less kinetic energy waste makes this the most efficient use of a gas turbine at low/medium altitudes and speeds up to 350 kt.
Advantage of a Turboshaft
More compact than the others.
Used on rotary assets
What gas turbines are designed for SUPERSONIC flight
Turbojet
What gas turbine is most efficient at low speeds?
Turboprop
A compressor stall occurs when a compressor operates _____ __ ___ ______.
Outside of its limits
List some causes of a compressor stall
- Wrong RAF over comp blades.
- A blade ‘stalls’.
- All comp blades in stage at same angle/RAF.
- Presented airflow is disrupted.
- Disrupted airflow can cause following stages to stall.
What are the indications of a compressor stall?
Increase in engine vibration.
Increase in Turbine Gas Temp (TGT).
Describe a compressor surge
Not a high enough pressure in the compressor therefore flame will migrate through compressor and force flame out front.
Indications of compressor surge
- Intake banging
- Large rise in Turbine Gas Temp (TGT)
- Loss of thrust
- Possible catastrophic compressor failure
A STALL is a ____ breakdown of airflow through the compressor.
PARTIAL
A SURGE is a ____ breakdown of airflow through the compressor.
COMPLETE
What design features can help prevent comp stalls and surging.
- Variable inlet guide/ stator vanes
- Multi-spool compressors
- Compressor bleeds
What are the 9 uses of oil in an aircraft?
- Reduce friction
- Reduce wear
- Cleaning
- Minimise corrosion
- Cooling
- Heating (fuel heat exchanger)
- Hydraulic Fluid
- Chip detection
- Engine status (Oil T+P)
Fluid introduced between two load bearing surfaces is known as _____
LUBRICATION
What is hydrodynamic lubrication regime?
Relatively thick layer of oil between surfaces
What are the 3 lubrication regimes?
Hydrodynamic
Boundary
Mixed
What is Boundary layer lubrication?
Very thin layer of oil between surfaces.
Often seen during start up conditions.
Components of the Engine Oil system (6)
- Oil Tank
- Oil Pump
- Oil Cooler
- Filter Assembly
- Magnetic Chip detection
- Monitoring Instruments
What are the 2 key parameters we want to know about the engine oil system?
Temp and Pressure
Components of the Fuel system (7)
- LP fuel cock
- Fuel cooled oil cooler
- Fuel filter
- HP fuel pump
- Throttle valve
- Fuel control unit
- HP shut-off valve
Everything upstream (before) the HP fuel pump is known as the ______ pressure part of the system
LOW pressure
Everything downstream (after) and inc. the HP fuel pump is known as the ______ pressure part of the system
HIGH pressure
List some uses of the air from the Air system
- Engine cooling
- Blade cooling
- Air sealing
- Bleed air
- Anti-icing
Why is engine cooling required?
Internal temperatures are very high
What is used to cool the engine?
Combination of Air and Oil
Which blades typically require the most amount of cooling?
Turbine blades
How are blades in the engine cooled?
Through longitudinal holes in the internals of the blade structure
Film cooling on leading and trailing edges of the blades
What info/data about the engine is typically provided to the pilots?
- Eng Temp
- Eng Speed
- Torque
- Fuel Flow, T+P
- Oil T+P
Bleed air can be used for
- Airframe anti-icing
- Cabin pressurisation
- Fuel tank pressurisation
- Pneumatic Services
- Air blown flight controls
Anti-icing air can be supplied to
- Engine intakes
- Inlet guide vanes
- Inlet cone
Engine temperature is measured using ______
THERMOCOUPLES
What piece of equipment is used to measure engine speed?
Tacho-Generator
List some accessory systems driven by the gearbox (9)
- Fuel Control Unit (FCU)
- HP Fuel Pump
- LP Fuel Pump
- Oil Pumps
- Scavenger Pumps
- Centrifugal breather
- Tacho-generator
- DC starter/generator
- Air Con Compressor
The frequency of the Tacho-Generator is ______ proportional to the speed of the engine.
DIRECTLY
Torque is measured by the ________
TORQUEMETER
Name the 4 types of fuel
AVGAS
AVTUR
AVTAG
AVCAT
What 3 fuels include FSII?
AVTUR
AVTAG
AVCAT
Piston Engines use what fuel?
AVGAS