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The Fly Higher Tutorial II Aircraft in the air: What Jet

Engines Do

Image Source: Rolls Royce Plc. 2013

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Birds are able to fly because of a variety of specialised adaptations. They need extreme level of energy to fly in the air which comes from their high metabolisms. Because of their very light bodies, birds are able to produce both the required lift and propulsion using their flight feathers.

Introduction: How can birds fly in the air?

Image source http://gimnasio-altair.com/webquest/flight/

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A short video to demonstrate how birds can fly in the air :

Introduction: How can birds fly in the air?

Video source Youtube Acknowledgement: www.pendulumswingmedia.com

http://www.youtube.com/watch?v=3So7OMwNgy8

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Like birds, for aircraft to stay in the air we need thrust and lift. Where do these come from?

Why can we not just copy the birds?

And what is Thrust ? Let us look at the basic concept.

Introduction: Thrust

Image source http://www.kids.ct.gov/kids/cwp/view.asp?q=330926

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Based on Newtons Third Law: Every action has an equal and

opposite reaction

Demo: Fill the balloon with air and let it go in free space - What happens ?

So what happens to an aircraft fitted with a jet engine?

Introduction: The physics behind thrust

Source http://www.bloodhoundssc.com/shop/balloon-car-kit

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Hot exhaust gases from the aircrafts jet engines push on the air which in return produces opposite reaction on the engines. As the engines are securely fitted to the aircraft body, the aircraft moves in the forward direction.

Who came up with this brilliant idea?

Introduction: Aircraft in forward motion

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In the 18th Century Sir Isaac Newton, an English physicist and mathematician proposed a theory of rearward-channelled explosion which could propel a machine forward at a great speed. He foresaw a use of his third law of motion which we now take for granted.

History How did it begin?

Newtons Steam Wagon

Source http://www.globalsecurity.org/military/library/policy/army/fm/1-506/Ch2.htm

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In 1903 , the year of the Wright Brothers first flight, their wooden and canvas bi-plane was fitted with a 12 horse power petrol engine.

Their engine was a basic mechanical design, remarkably similar to a modern, four-cylinder car engine.

Image courtesy: http://wright.nasa.gov/airplane/Images/eng2.gif

History How did it begin?

http://www.google.co.uk/url?sa=i&rct=j&q=the+wright+brothers+plane&source=images&cd=&cad=rja&docid=_BS8urismEJhQM&tbnid=PdVrBHl_E1098M:&ved=0CAUQjRw&url=http://wright.nasa.gov/ROGER/models.htm&ei=5DVkUaaVBe_40gW7-YDICA&bvm=bv.44990110,d.d2k&psig=AFQjCNG7SQ8OxBge1cUTF-U8Gnk280sarw&ust=1365608284534260

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Their aeroplane, Kitty Hawk, depended upon the propeller to give her thrust; the engine simply turned the propeller.

Most modern, small light aircraft still use propellers Can you suggest why?

History How did it begin?

In the next 30 or 40 years, aircraft became single-winged, metallic tubes; their engines were more powerful and fuel-efficientbut this principle did not change.

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In 1930 Sir Frank Whittle from England patented the Turbo jet engine. By April 1941 (early in World War II), the new engine was ready for flight testing. The first flight of a Turbojet, the Gloster E28/39, was made on 15th May 1941 at Cranwell in Lincolnshire, England.

The engines exhaust would propel the aircraft

NO PROPELLER!!

History How did it begin?

Source: www.frankwhittle.co.uk/content.php?act=viewDoc&docId=15&level=top

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Fundamentals Engine function

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In the basic internal combustion engine the combustion is, in truth, an explosion. This explosive energy is used to drive a set of pistons, and the exhaust is regarded as waste.

The pistons can then turn the wheels of a car, the blades of a pump. or the propeller of an aircraft.

Fundamentals Engine function

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In the Jet Engine, the exhaust is not simply waste, but the source of the thrust that moves the aeroplane forward.

Fundamentals Engine function

Source Youtube Inside a Jet Engine Acknowledgement www.wydea.com

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There are even different kinds of jet engines.

The Airbus A380 with 525 Passenger the largest long range civil aircraft in the world uses turbofan engines, refined versions of Whittles original that include a massive fan to accelerate the air entering the jet engine as

well as contribute to the thrust exactly as a propeller does .

Turbofan Turbofan

Types of Engine Why are different engines used?

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Different aircraft need different types of engine Can you guess what these are and why they are used?

Ramjet

Turbojet

Rocket

Types of Engine Turbofans are not the only choice

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQ1V5eCFRbPSkLKrz68Ab_AGlud0UDUDQ0vR7dmp_OhHr1Xqu8NDg

http://img.bhs4.com/64/e/64e5d996fcdce95195acd4621cb79fb4f8ec776a_large.jpg

https://upload.wikimedia.org/wikipedia/commons/d/d3/Atlantis_taking_off_on_STS-

27.jpg

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Different aircraft need different types of engine Can you guess what these are and why they are used?

Turbo-prop

Piston-prop

Types of Engine Turbofans are not the only choice

http://www.instablogs.com/wp-content/uploads/2012/07/hb350i_vM1uz_25013.jpg

http://air-and-space.com/20050812%20Hawthorne/DSC_3008%20An-2%20N2AN%20cn43798%20left%20front%20landing%20l.jpg

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The choice of engine is based on : Thrust Required Performance Efficiency Cost Maintenance

Civil aircraft require

fuel efficient engines.

Military Aircraft require high performance engines.

Types of Engine Engyne section

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Engine Components (Turbojet)

Whittles original was a Turbojet engine like this

Types of Engine Turbojet

source: http://commons.wikimedia.org/wiki/File:Turbojet_operation-axial_flow-en.svg

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The airlines choice. Turbofans are like Turbojets but also have a large fan accelerating the airs entry into the engine and adding to the thrust as an internal propeller.

Types of Engine Turbofan

source : http://upload.wikimedia.org/wikipedia/commons/c/c0/Turbofan_operation.png

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Turbo-Props have external propellers but use the jet engine idea to drive them

Unlike Piston-Prop engines, Turbo-Props do not have pistons

Types of Engine Turbo-prop

Source http://upload.wikimedia.org/wikipedia/commons/4/4e/Turboprop_operation.png

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Ramjet do not have compressors, fans and turbines like other jet engines.

Technically, ramjets are the simplest form of jet engine. But they cannot produce thrust at zero speed, so Ramjet aircraft

need other mechanisms to start their flight.

Types of Engine Ramjet

source - http://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Ramjet_operation.svg/300px-Ramjet_operation.svg.png

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Unlike an aircraft engine, rocket engines carry both fuel and oxygen to energise the gas in

the combustion chamber, before it exits through nozzle.

Why do you think this is?

Types of Engine Rocket engine

source: http://www.grc.nasa.gov/WWW/k-12/VirtualAero/BottleRocket/airplane/Images/rockth.gif

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Summary

Engine Summary Turbojet Animation

Video source Youtube Acknowlegement www.rendermedia.co.uk

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Link for Engine Simulator: http://www.geaviation.com/education/engines101/

Further Learning GE Engine Simulator

http://www.geaviation.com/education/engines101/

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Consortium

/groups/Fly-Higher-Project-4737756

/flyhigherproject

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Follow us on

www.flyhigher.eu For further information flyhigher@inovamais.pt

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