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How does a plane fly?


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An explanation of how airplanes are able to fly

Published in: Technology
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How does a plane fly?

  1. 1. Air transportation is the safest form of transport in theworld.Donkeys kill more people annually than plane crashes.One wind shield or window frame of the Boeing 747-400s cockpit, cost as much as a BMWThere are approximately 200,000 flights every dayaround the world.Every 3 seconds in the world a plane makes a landing
  2. 2. 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?”
  3. 3. 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.
  4. 4. 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.
  5. 5. 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.
  6. 6. When all this processes take place inside the engine, huge amounts of hot air is forced outside at high speed. And applying newtons third law of motion, “for every action there is an equal and opposite reaction,” Thesame force from which the air was pushed backwards, the engine, and the plane, will be pushed forward. Air pushed backwards Plane pushed forward
  7. 7. 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 twoimportant changes:1. It is lowered in pressure2. It is accelerated downwards
  8. 8. The air on the upper surface on the wing is pushed downwards following theshape of the wing. So applying newtons 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.
  9. 9.  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).
  10. 10.  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.
  11. 11. When the angle of attack exceeds 15degrees, the air starts to separate from the wing and a stall is created. The angle of attack is controlled by the elevators.
  12. 12. When enough thrust is provided to the aircraft either by a propelleror 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.
  13. 13. Located at the back of the wing.They extend and contract to alter the shape of the wing in orderto 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
  14. 14. When flaps extend they alter the shape of the wing making the bend on its upper surface wider. This new shape of the wing divertsmore air downwards creating more lift. When flaps retract the bend in the wing issmaller, 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
  15. 15. • 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.
  16. 16. When the aileron on one of the wings rises, lift is slightly decreased in theend of the wing. Simultaneously the aileron in the other wing will decreaseand slightly increase the lift in the end of the wing. So lift increases in onewing and decreases in the other causing the plane to roll. Ailerons are used for steep turns Raised aileron Normal aileron Decreased aileron
  17. 17. • 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.
  18. 18. • 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
  19. 19. 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 Newtons third law of motion). Consequently the nose rotates to the right. When the rudder deflects to the left the same process occurs and theRudders are used for small turns nose is rotated to the left.
  20. 20. Elevators: control the pitch of the planeMove the nose up or downRudders: control the yaw of the planeRotate the nose of the plane to the leftor to the rightAilerons: control the roll of the planeTilt the wings up or down
  21. 21. Surfaces that extend or retract on top of the planes wing They are used for stopping the aircraft when landed as theyincrease reasonably the amount of drag (air resistance) acting on the aircraft
  22. 22.  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
  23. 23.  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
  24. 24.  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
  25. 25.  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
  26. 26.  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.
  27. 27.  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
  28. 28. • (n.d.). Retrieved November 11, 2012, from How a jet engine works:• Air Museum. (2006). Retrieved November 17, 2012, from How does an airplane fly?:• Anderson, D. (2012, July 20). All star networks. Retrieved November 07, 2012, from How airplanes fly:• Arce, O. (2012, November 22). How do airplanes stay in the air? (P. Chatain, Interviewer) Bogotá, Cundinamarca, Colombia.• Benson, T. (2010, September 10). NASA. (R. J. Dr, Ed.) Retrieved November 02, 2012, from Dinamics of flight: 12/UEET/StudentSite/dynamicsofflight.html• Brain, M. (n.d.). How stuff works. Retrieved October 02, 2012, from How gas turbine engines work:• GE aviation. (2012). Retrieved November 13, 2012, from engines 101:• Kristin, P. (2009). Airplanes. Abdo Publishing.• Kunzig, R. (2001, April 01). The physics of airplanes. Discover magazine .• Magafactories. (2012). Boeing 747-8 , season 7 , episode 2. USA: National Geaographic.• Marshall Brain, R. L. (n.d.). How stuff works. Retrieved October 12, 2012, from How airplanes work:• Porque vuelan los aviones? (2005, April 12). Eroski Consumer .
  29. 29. • Florbor007, United Airlines Boeing 767 Windy Landing Brussels Airport, Jan 18, 2012, (youtube)• Curuxiane, Air Malta A320 - take-off, Feb 14, 2007, (youtube)
  30. 30. • jDQTsaAGrIU/T9JkLYmT8OI/AAAAAAAANHs/zG7xilRSn7Q/s1600/airplane20landing-jj-001.jpg••••••••••••
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