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Lecture 3b: Aircraft Engines
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1903- 1940s: Propeller + Piston
Engines Era From 1903 (Wright bros.)
until the Early 1940s, allaircraft used the pistonengine combined with
propeller as theirpropulsion system.
Piston engine is justsimilar with car engineexcept with severaldifferent.
A propeller is essentiallya type of fan whichtransmits power byconverting rotationalmotion into thrust to
propel the aircraft (moveforward).
Piston engine uses theenergy produced by
burning a mixture of air
and fuel to drive the
propeller.
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3
Piston engineMain parts
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Piston engineDifferent configurations of piston engines
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5
Piper PA-28 Cherokee
Engine(s):
-Lycoming piston engine
- 4 cylinders
- 110 hp
Propeller(s):
- 2 blades fixed pitch
Performance:
- Max. speed 127kt
- Operational ceiling 11000 feet
Piston engineExamples
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6
Antonov AN-2
Engine(s):
-PZL piston engine, RADIAL
-9 cylinders
-1000 hp
Propeller(s):
-4 blades variable pitch
Performance:
-Max. speed 139kt
-Operational ceiling 13000 feet
(approx.)
Piston engineExamples
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The differences between piston aircraft
engines and car engines Crankshaft The crankshaft in an piston aircraft engine
turns a propeller, crankshaft in car engine is used to movethe wheels of the car.
Weight the piston aircraft engine must be lightweightcompare to car engine.
Power demand to run the engines- the piston aircraftengine demands high power for very long times compareto car engines
Numbers of engine parts - an aircraft engine has at least
two sets for every parts, including ignition system (sparkplugs and magnetos) and fuel pumps compare to carengine that only have one set.
Operating environment different- an aircraft engine noneed radiator for air-cooling compare to the car.
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Propeller + Piston
Engine Aircraft Very efficient for low speed flight.
Lower load capacity compared to similar sized jetpowered aircraft.
Consumes less fuel, thus cheaper and much moreeconomic than jets.
Quiet, but fly at lower speeds.
The best option for people who need to transport afew passengers and/or small amounts of cargo.
Best choice for pilots who wish to own their ownaircraft.
Propellers are not used on high speed aircraft.
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Jet Engine History
1931: 1st turbojet engine designed 1930 by Sir
Frank Whittle
1939: The 1
st
jet aircraft (Heinkel He 178) wasdeveloped in England and Germany
1943: The first jet fighter aircraft,Messerschmitt
Me 262 went into service in the German
Luftwaffe.
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History of Aircraft Propulsion
1944 (After World War 2)-Today :
Airplanes usedjet engines to generate thrust. Jet engines also referred to as Gas Turbine
Engines.
Various types (turbo-jet, turbo-prop, turbo-shaft,turbo-fan , ramjet, scramjet)
Messerschmitt Me-262 : 1st operational jet-poweredaircraft
German V-1 bomb (pulse jet engine): 1st applicationfor military purposes.
Bell P-59: 1st American aircraft
MiG-15: 1st Soviet jet aircraft.
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Jet Engines
Jet aircraft make use of turbines for the creation ofthrust.
Consumes more fuel but provide much more thrust
than a piston engine. Fly faster than propeller driven aircraft.
Greater weight capacity
Example: Airbus A340 and Boeing 777, can carry
hundreds of passengers and several tons of cargo,and are able to travel for distances up to 13 thousandkilometers.
Noisy, this makes jet aircraft a source of noise
pollution.
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Newton's 3rd law
The theory of jet propulsion is based on the Newtonsthird Law, which state that For every action there isan equal and opposite reaction.
When the jet engine is operating, it draws a lot of airfrom the front and after air-fuel burns the gas ejectsat high speed.
During this process, the engine applies force to thegas and lets the gas accelerate in the backwarddirection and in the meantime, the gas also gives theengine a reactive force to push the aircraft to moveforward.
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Turbo-jet Engine
Inlet- inlet is the opening at the front of engine, it allows the outside air to enterthe engine.
Compressor compressor is made up of fans with many blades, it compress theair and raises the pressure & temperature of the air, the compressed air then isdelivered to the burner.
Burner Burning process occur here. Fuel is sprayed to the compressed air .The
mixture of the fuel + air will be burned. The results is heated gas with high energy,high pressure and high temperature.
Turbine- turbine used some of the heated gas energy to turn the compressor . Thisenergy is transferred through the shaft.
Nozzle- The balance of heated gas energy exits through the nozzle at very highspeed. This causes thrust.
As the jets of gas shoot backward, the engine and the aircraft are thrust forward.(Newton 3rd Law)
Thrust
Newton's 3rd law: For every action there is an equal and
opposite reaction. This is called thrust.
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Turbo-prop Engine
The propeller located at the front of engineThe propeller converts the power developed by the
engine into thrust as efficiently as possible under all
operating conditions.
These aircraft are popular with regional airlines, asthey tend to be more economical on shorter journeys.
Hercules-1 C130
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Turbo-fan Engine
Similar to the turboprop, except a fan replaces
the turboprop propeller.
Larger fan at the front provides thrust in thesame way as a propeller.
The turbofan engine has a front fan, which runs
at the same speed as the compressor and fan
turbine located at the back to drive the fan. Most modern airliners use turbofan engines
because of they can produce high thrust, lower
fuel consumption and low engine-noise.
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Rocket EngineRocket Engine A rocket engine produces thrust by
burning a fuel at high pressure andexhausting the gas through a nozzle.
The oxygen for combustion is carried with
the propulsion system. High temperatures and pressures is built
up, the are used to accelerate the exhaustgases through a rocket nozzle to produce
thrust. The heavier the rocket , the greater thrust
needed to get it off the ground.
Newton 3rd Law: To every action there isan equal and opposite reaction."
1717
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Differences between Jet engine
and Rocket engineThrust direction
Jet engine is an engine using jet propulsion for forwardthrust .
Rocket engine is an engine using jet propulsion forupward thrust.
Source of oxygen
Jet engines do not have their own source of oxygen.Outside air is sucked into the engine to act as anoxidizer
There is no air in space. Rockets have their own oxygensource, either a liquid tank, or mixed in with the solid
fuel for combustion.
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Rocket vs Missile
Purpose
Rocket mission is to send the satellite to
outer space. Missile mission is as a weapon to attack
high value target.
Guidance Rocket no guidance system.
Missile has a guidance system.