PRINCIPLES OF FLIGHT

1. PRINCIPLES OF FLIGHT Key Revision Topics Click on ‘F5’ to start.

2. PRINCIPLES OF FLIGHT Chapter 1 Lift and Weight Contents List. Chapter 2 Thrust and Drag Chapter 3 Stability and Control Chapter 4 Stalling Chapter 5 Gliding Chapter 6 Helicopters exit

3. Contents List. Click on a chapter. PRINCIPLES OF FLIGHT Chapter 1 Lift and Weight Chapter 2 Thrust and Drag Chapter 3 Stability and Control Chapter 4 Stalling Chapter 5 Gliding Chapter 6 Helicopters exit

4. PRINCIPLES OF FLIGHT Chapter 1 Lift and Weight Return to contents list exit

5. Lift and Weight How can an aircraft, which is so much heavier than air, be supported by that air? Sir Isaac Newton’s third law states: “To every action, there is an equal and opposite reaction.” A vehicle weighing 1 tonne is supported by the road pressing up with a force of 1 tonne. A boat weighing 10 tonnes is supported by a 10 tonne upward force from the water, otherwise it would sink.

6. Lift and Weight How can an aircraft, which is so much heavier than air, be supported by that air? Sir Isaac Newton’s third law states: “To every action, there is an equal and opposite reaction.” Aircraft can only remain airborne while they are actually moving – if they stop moving they cease flying. The upward force to support the aircraft is only there when the aircraft is moving forwards through the air.

7. Lift and Weight How can an aircraft, which is so much heavier than air, be supported by that air? Sir Isaac Newton’s third law states: “To every action, there is an equal and opposite reaction.” This upward force is generated by the aircraft’s wings as they pass through the air. We must understand how wings moving through the air create that upward force, known as ‘lift’.

8. Which scientist formulated laws which explain the way things move? a) Morgan. b)Newton. c) Riddeley. d)Einstein.

9. Which scientist formulated laws which explain the way things move? a) Morgan. b) Newton. c) Riddeley. d) Einstein.

10. That scientist’s 3rd law states that: a)Every object has weight. b)Weight equals lift during flight. c)Every force causes an object to move. d) Every action has an equal and opposite reaction.

11. That scientist’s 3rd law states that: a) Every object has weight. b) Weight equals lift during flight. c) Every force causes an object to move. d) Every action has an equal and opposite reaction.

12. Lift and Weight In this wind tunnel experiment the air is passing from ‘A’ to ‘C’ through a constriction at ‘B’. As the amount of air leaving at ‘C’ is the same as the amount entering at ‘A’, the air must speed up as it passes the narrowest point ‘B’.

13. Lift and Weight Another scientist, Bernoulli, discovered that in areas where airspeed increases, the air pressure decreases. In the wind tunnel experiment above, the air pressure measured at ‘B’ will be less than at ‘A’ and ‘C’.

14. In the diagram below, air is flowing past a constriction. What has happened to the air pressure at point B? a) It is lower than at point A. b)It is the same as at point C. c) It is greater than at point C. d)It is greater than at point A.

15. In the diagram below, air is flowing past a constriction. What has happened to the air pressure at point B? a) It is lower than at point A. b) It is the same as at point C. c) It is greater than at point C. d) It is greater than at point A.

16. For air moving in a smooth streamline flow, if the air is made to speed up, what happens to the pressure of the air where it is flowing faster? a) It increases. b) It fluctuates wildly. c) It decreases. d)It remains constant.

17. For air moving in a smooth streamline flow, if the air is made to speed up, what happens to the pressure of the air where it is flowing faster? a) It increases. b) It fluctuates wildly. c) It decreases. d) It remains constant.

18. Bernoulli’s Principle says that: a)Where air speed decreases the temperature increases. b) Where air is speeded up the pressure increases. c)Where air is speeded up the pressure decreases. d)Where air speed increases the temperature increases.

19. Bernoulli’s Principle says that: a) Where air speed decreases the temperature increases. b) Where air is speeded up the pressure increases. c) Where air is speeded up the pressure decreases. d) Where air speed increases the temperature increases.

20. Lift and Weight A simple experiment you can do to demonstrate this principle is illustrated in this picture. Blowing along the top of this sheet of paper causes it to lift into line with the airflow. By blowing and speeding up the air over the top, you have reduced the pressure above the paper, so the normal air pressure below the paper pushes it up.

21. When this person blows along the top of the paper, the paper rises. This is because of: a) The skin friction that develops along the top of the paper. b) A reduction in the air pressure along the top of the paper. c)The vortices that form along the top of the paper. d)A rise in the air pressure along the top of the paper.

22. When this person blows along the top of the paper, the paper rises. This is because of: a) The skin friction that develops along the top of the paper. b) A reduction in the air pressure along the top of the paper. c) The vortices that form along the top of the paper. d) A rise in the air pressure along the top of the paper.

23. Lift and Weight The top surface of a wing is shaped so that the air which flows between it and the undisturbed air a little way above the wing is effectively flowing through a constriction. undisturbed air The air flows over the wing at increased speed and therefore at reduced pressure.

24. Where is the airflow fastest in this diagram of an aerofoil in an airflow? a) W b) X c)Y d) Z

25. Where is the airflow fastest in this diagram of an aerofoil in an airflow? a) W b) X c) Y d) Z

26. Where is the air pressure lowest in this diagram of an aerofoil in an airflow? a) W b) X c)Y d) Z

27. Where is the air pressure lowest in this diagram of an aerofoil in an airflow? a) W b) X c) Y d) Z

28. As air passes over the top surface of a wing in normal flight, its speed will: a) Increase. b)Reduce considerably. c) Reduce slightly. d)Remain constant.

29. As air passes over the top surface of a wing in normal flight, its speed will: a) Increase. b) Reduce considerably. c) Reduce slightly. d) Remain constant.

30. Why is lift produced when air flows over the top surface of a wing? a) The air pressure rises because the air is speeded up. b) The air pressure rises because the air is slowed down. c) The air pressure falls because the air is speeded up. d)The air pressure falls because the air is slowed down.

31. Why is lift produced when air flows over the top surface of a wing? a) The air pressure rises because the air is speeded up. b) The air pressure rises because the air is slowed down. c) The air pressure falls because the air is speeded up. d) The air pressure falls because the air is slowed down.

32. Lift and Weight All parts of a wing generate lift, some parts more than others. lift forces oncoming air

33. Lift and Weight The top surface normally generates more lift than the bottom surface. lift forces oncoming air

34. Lift and Weight The top surface may generate up to 80% of the total lift. lift forces oncoming air

35. Lift and Weight The greatest amount of lift on the top surface occurs where the surface is curved the most. lift forces oncoming air

36. Lift and Weight All of the lift forces act at 90 degrees to the oncoming airflow. lift forces oncoming air

37. Lift and Weight All of the lift forces act at 90 degrees to the oncoming airflow. lift forces oncoming air

38. Where is the greatest amount of lift normally generated on an aerofoil? a) Top surface. b) Bottom surface. c) Trailing edge. d)Leading edge.

39. Where is the greatest amount of lift normally generated on an aerofoil? a) Top surface. b) Bottom surface. c) Trailing edge. d) Leading edge.

40. Lift is obtained from almost all parts of the wing but not equally from every part. About how much is obtained from the top surface of an aircraft wing? a) Up to 80%. b)Up to 50%. c) Up to 33%. d)Up to 25%.

41. Lift is obtained from almost all parts of the wing but not equally from every part. About how much is obtained from the top surface of an aircraft wing? a) Up to 80%. b) Up to 50%. c) Up to 33%. d) Up to 25%.

42. On a general purpose aerofoil, the greatest amount of lift occurs: a) Just forward of the trailing edge. b)At the centre of the bottom surface. c) Where the top surface is not curved. d)Where the top surface is curved the most.

43. On a general purpose aerofoil, the greatest amount of lift occurs: a) Just forward of the trailing edge. b) At the centre of the bottom surface. c) Where the top surface is not curved. d) Where the top surface is curved the most.

44. In what direction relative to the direction of the oncoming air, or path of the aircraft, do the lift forces act? a) At about 4 degrees. b)The opposite direction. c) At 90 degrees. d)The same direction.

45. In what direction relative to the direction of the oncoming air, or path of the aircraft, do the lift forces act? a) At about 4 degrees. b) The opposite direction. c) At 90 degrees. d) The same direction.

46. Lift and Weight Instead of looking at the thousands of lift forces generated by a wing, we add them together and represent them with a single line. lift forces oncoming air

47. Lift and Weight Instead of looking at the thousands of lift forces generated by a wing, we add them together and represent them with a single line. oncoming air

48. Lift and Weight The point at which all the lift can be said to act is the ‘centre of pressure’. oncoming air

49. Lift and Weight The point at which all the lift can be said to act is the ‘centre of pressure’. The idea is similar to finding the centre of gravity of a ruler by balancing it on your finger. All the small forces of gravity acting on the ruler balance about the centre of gravity.

50. The point on a wing at which all the lift forces are said to act is: a) Centre of pressure. b)Dynamic centre. c) Pressure point. d)Static point.