An explanation of how airplanes are able to fly

2. Air transportation is the safest form of transport in the
world.
Donkeys kill more people annually than plane crashes.
One wind shield or window frame of the Boeing 747-
400's cockpit, cost as much as a BMW
There are approximately 200,000 flights every day
around the world.
Every 3 seconds in the world a plane makes a landing

3. In this moment there are thousands of planes traveling through
the air.
Machines that travel at heights over 12,500 meters above sea
level and at speeds greater than 850 km/h
But, how is this possible?????
In this presentation we will solve the question “How
does an airplane fly?”

5. There are 4 aerodynamic forces acting on an airplane:
• Thrust: Is the force that moves an airplane forward through space.
Caused by a propeller or a jet engine.
• Drag: Is the force that resists the airplane from moving forward. It is the
friction or air resistance that stops the plane.
In order for flight to take place, thrust must be equal or greater than drag.
 Lift: Is the upwards force that keeps an airplane in the air. It is caused by
the shape of the wings.
 Weight: Due to gravity every object on earth has weight. Weight is the
force that pushes an object down (due to gravity)
In order for flight to take place, lift must be equal or greater than weight.

7. 1. Fan: Rotates at high speed at sucks in large amounts of air.
2. Compressor: Made up of stationary and rotating blades. Rotating blades push
air into stationary blades which compress the air and rises its pressure.
3. Combustor: Here, the high speed, compressed air enters and it is sprayed
with fuel from fuel injectors. The compressed air and jet fuel mixture burns
forcing exhaust gases to leave rapidly through the rear of the engine.

8. 4. Turbine: Fan-like set of blades which are rotated by the high speed gases which
are being exhausted by the combustor. It is connected to the compressor and
to the fan so its rotation also helps rotate the compressor and the fan for the
new entering air.
5. Mixer: Not all the air sucked in enters the compressor and the air that didn’t
enter, bypasses the engine by its side, then in the mixer it is mixed with the hot
air being exhausted.
6. Nozzle: Exhaust duct of the engine. Here is where all the air leaves the engine.
Atmosphere Hot, high speed air
air sucked in thrown out.

9. When all this processes take place inside the engine, huge amounts of hot
air is forced outside at high speed. And applying newton's third law of
motion, “for every action there is an equal and opposite reaction,” The
same force from which the air was pushed backwards, the engine, and the
plane, will be pushed forward.
Air pushed backwards Plane pushed forward

11. Lift occurs when a moving fluid is deflected by a solid object. In
this case, the wing splits the air into two directions (up and
underneath the wing)
The shape of the wing is what enables it to produce lift. The wing of an
aircraft is curved in the upper surface and its flatter in the bottom
surface.
The air that passes through the upper surface of the wing undergoes two
important changes:
1. It is lowered in pressure
2. It is accelerated downwards

12. The air on the upper surface
on the wing is pushed
downwards following the
shape of the wing. So applying
newton's third law of motion
“for every action there is an
equal and opposite reaction,”
if the wing pushed the air
downwards, the air will apply
an equal and opposite
reaction and push the wing
upwards and produce lift.

13.  The air that is forced to the upper surface of the wing must also travel a
longer distance (due to the bend in the wing) therefore it must go
faster. And faster moving air has a lower pressure due to that molecules
are more spread apart.
 As the air on top of the wing has less pressure than the air on
bottom, the higher pressure air on the bottom of the wing will push the
wing upwards producing lift.
 As the speed of the aircraft increases so does the lift produced (more
air is diverted downwards and the difference in air pressure from the
top and bottom surfaces of the wings is wider).

14.  The angle of attack is the angle that the wings presents to the
oncoming air. The greater the angle of attack, the greater the
lift produced because the air is diverted downwards in a
steeper angle. Until a certain point.
Usually a wing has to achieve a
negative angle of attack to
produce zero lift.

15. When the angle of attack exceeds 15
degrees, the air starts to separate from the wing
and a stall is created.
The angle of attack is
controlled by the
elevators.

17. When enough thrust is provided to the aircraft either by a propeller
or a jet engine, thrust will overcome drag and the airplane will start to
gain speed.
As speed increases so will the lift provided by the wings. When a
certain speed is reached, lift will overcome weight and the airplane
will be pushed up and into the air.

19. Located at the back of the wing.
They extend and contract to alter the shape of the wing in order
to achieve the necessary lift.
When flaps extend more lift is
created and when they retract
less lift is created.
Flaps are constantly
operated during a flight

20. When flaps extend they alter the shape of the
wing making the bend on its upper surface
wider. This new shape of the wing diverts
more air downwards creating more lift. When
flaps retract the bend in the wing is
smaller, diverting less air downwards and thus
creating less lift.
Different flap positions are useful at
different stages of the flight
Flap not extended: used when
cruising, climbing and descending (no
extra lift)
Flap partially extended: used for takeoff
and initial climb (extra lift)
Flap fully extended: used on approach to
landing and landing (more lift with lower

21. • Horizontal flaps located near the end of the wings.
• They act the same way as normal flaps, when raised, lift decreases and
when lowered lift increases (based on the same principle).
• The ailerons on both wings work simultaneously and opposite to each
other, this means that when the aileron on the right wing is lowered, the
one on the left wing will be raised proportionally (in the same amount) and
opposite.

22. When the aileron on one of the wings rises, lift is slightly decreased in the
end of the wing. Simultaneously the aileron in the other wing will decrease
and slightly increase the lift in the end of the wing. So lift increases in one
wing and decreases in the other causing the plane to roll.
Ailerons are used for
steep turns
Raised aileron
Normal aileron
Decreased aileron

23. • Small flaps on the horizontal wing of the tail.
• They work simultaneously but not opposite to each other.
• The same principle is applied, when the elevators are raised, lift is
slightly decreased and when they are lowered lift is slightly increased.

24. • When the elevators are raised lift decreases in the tail of the
plane, causing it to go down and raising the nose.
• When the elevators are lowered lift in the tail is increased, causing it
to go up, pointing the nose down.
Elevators are raised, lift in the tail Elevators are lowered, lift in the tail
decreases, nose points up. increases, nose points down.
During takeoff, ascent and During descent and approach to
landing landing

25. Vertical flap on the vertical wing of the tail which turns left
or right forcing the plane in the opposite direction.
When the rudder deflects to the
right, it diverts the air to the right
and thus forces the tail of the plane
to the left (applying Newton's third
law of motion). Consequently the
nose rotates to the right.
When the rudder deflects to the left
the same process occurs and the
Rudders are used for small turns nose is rotated to the left.

26. Elevators: control the pitch of the plane
Move the nose up or down
Rudders: control the yaw of the plane
Rotate the nose of the plane to the left
or to the right
Ailerons: control the roll of the plane
Tilt the wings up or down

27. Surfaces that extend or retract on top of the planes wing
They are used for stopping the aircraft when landed as they
increase reasonably the amount of drag (air resistance) acting on
the aircraft

29.  The plane taxis until it is lined up with the runway
 When lined up with the runway flaps are lowered until about halfway
through (to gain more lift)
 When authorization is given for takeoff, turbines are forced to maximum
power and the airplane will start to gain speed

30.  As the plane gains speed, the wings will start to produce more and more lift
 After some time (when enough speed is gained) the pilot will rotate the
plane (by the use of elevators), changing the angle of attack of the wings
creating enough lift (which overcomes weight) to lift the plane up

31.  After about 20 seconds from takeoff the plane will rotate (roll) heading
towards its destination (by the use of ailerons)
 Then the plane will keep climbing until reaching a certain altitude
 There the turbines are lowered to about 75% of power and the angle of
attack is adjusted in order to achieve zero lift.
 The plane starts to cruise through the sky

32.  At the beginning of the descent the plane is rotated downward (pointing the nose
down) by the use of elevators.
 Turbines are lowered to about 50% of their power
 As it descends it lowers flaps until they reach their maximum extension

33.  When close to the runway the landing gear will be extended
 In this moment turbines are lowered to minimum power (about 40%) and the
plane is rotated pointing the nose up.
 In this moment the speed of the aircraft is so slow, that the lift produced is
slightly lower than weight.
 This will cause the plane to starts descending slowly as it approaches the
runway.

34.  As soon as the plane touches the runway, brakes and speed brakes are applied
to stop the airplane quicker.
 Finally the airplane taxis to its parking lot

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•
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•
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•
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•
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•
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•
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39. • http://wingsovermars.arc.nasa.gov/images/Pitch.gif
•
• http://www.nasa.gov/images/content/452494main_image_8.jpg
•
• http://cdn-www.airliners.net/aviation-photos/middle/7/7/5/0959577.jpg
•
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•
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