The Fly Higher Tutorial II
Aircraft in the air: What Jet
Engines Do
Image Source: Rolls Royce Plc. 2013
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Introduction:
How can birds fly in the air?
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’.
Image source http://gimnasioaltair.com/webquest/flight/
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Introduction:
How can birds fly in the air?
A short video to demonstrate how birds can fly in the air :
Please watch video 1 How do birds fly?
Source Youtube
Acknowledgement :
www.pendulumswingmedia.com
Edition Fly Higher
Video source – Youtube
Acknowledgement: www.pendulumswingmedia.com
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Introduction:
Thrust
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?
Image source http://www.kids.ct.gov/kids/cwp/view.asp?q=330926
And what is Thrust ? Let us look at the basic concept.
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Introduction:
The physics behind thrust
Based on Newton’s 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 ?
Source http://www.bloodhoundssc.com/shop/balloon-car-kit
So what happens to an aircraft fitted with a jet engine?
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Introduction:
Aircraft in forward motion
Hot exhaust gases from the aircraft’s 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?
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History
How did it begin?
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.
Newton’s Steam Wagon
Source
http://www.globalsecurity.org/military/libr
ary/policy/army/fm/1-506/Ch2.htm
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History
How did it begin?
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
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History
How did it begin?
Their aeroplane, Kitty Hawk, depended upon the propeller to give
her thrust; the engine simply turned the propeller.
In the next 30 or 40 years,
aircraft became singlewinged, metallic tubes;
their engines were more
powerful
and
fuelefficient…but this principle
did not change.
Most modern, small light aircraft still use
propellers… Can you suggest why?
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History
How did it begin?
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.
Source:
www.frankwhittle.co.uk/content.php?act=vie
wDoc&docId=15&level=top
NO PROPELLER!!
The engine’s exhaust would
propel the aircraft
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Fundamentals
Engine function
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Fundamentals
Engine function
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.
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Fundamentals
Engine function
In the Jet Engine, the exhaust is not simply waste, but the source of
the thrust that moves the aeroplane forward.
Please watch video 2 Inside a Jet Engine
Source Youtube
Acknowledgement : www.wydea.com
Edition Fly Higher
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Types of Engine
Why are different engines used?
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 Whittle’s 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
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Types of Engine
Turbofans are not the only choice
Different aircraft need different types of engine… Can you guess
what these are and why they are used?
Turbojet
http://img.bhs4.com/64/e/64e5d996fcdce9
5195acd4621cb79fb4f8ec776a_large.jpg
Rocket
https://upload.wikimedia.org/wikipedia/co
mmons/d/d3/Atlantis_taking_off_on_STS27.jpg
https://encrypted-
Ramjet
tbn2.gstatic.com/images?q=tbn:ANd9GcQ1V5eCFRb
PSkLKrz68Ab_AGlud0UDUDQ0vR7dmp_OhHr1Xqu8
NDg
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Types of Engine
Turbofans are not the only choice
Different aircraft need different types of engine… Can you guess
what these are and why they are used?
Piston-prop
Turbo-prop
http://www.instablogs.com/wpcontent/uploads/2012/07/hb350i_vM1uz_25013.jpg
http://air-and-space.com/20050812%20Hawthorne/DSC_3008%20An2%20N2AN%20cn43798%20left%20front%20landing%20l.jpg
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Types of Engine
Engyne section
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.
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Types of Engine
Turbojet
Engine Components (Turbojet)
Whittle’s original was a Turbojet engine like this
source: http://commons.wikimedia.org/wiki/File:Turbojet_operation-axial_flow-en.svg
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Types of Engine
Turbofan
The airlines’ choice.
Turbofans are like
Turbojets but also
have a large fan
accelerating the air’s
entry into the engine
and adding to the
thrust as an internal
propeller.
source : http://upload.wikimedia.org/wikipedia/commons/c/c0/Turbofan_operation.png
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Types of Engine
Turbo-prop
Turbo-Props have external propellers but use the jet engine idea to drive them
Unlike Piston-Prop engines, Turbo-Props do not have pistons
Source http://upload.wikimedia.org/wikipedia/commons/4/4e/Turboprop_operation.png
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Types of Engine
Ramjet
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.
source - http://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/Ramjet_operation.svg/300px-Ramjet_operation.svg.png
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Types of Engine
Rocket engine
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?
source: http://www.grc.nasa.gov/WWW/k-12/VirtualAero/BottleRocket/airplane/Images/rockth.gif
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Engine Summary
Turbojet Animation
Summary
Please watch video 3 Turbojet Animation
Source Youtube
Acknowledgement :
www.rendermedia.co.uk
Edition Fly Higher
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Further Learning
GE Engine Simulator
Link for Engine Simulator:
http://www.geaviation.com/education/engines101/
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Consortium
Follow us on
www.flyhigher.eu
/groups/Fly-Higher-Project-4737756
/flyhigherproject
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For further information flyhigher@inovamais.pt
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