Lecture+3b Aircraft+ +Engine

8/6/2019 Lecture+3b Aircraft+ +Engine

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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.

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