1. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Aerodynamics Chapter 1 Forces Acting on an Airplane

2. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-1. Drag counteracted by thrust.

3. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-2. The airplane is supported by the ground, and in the air by lift.

4. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-3. The four main forces are in equilibrium during unaccelerated flight.

5. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-4. Weight acts downward through the center of gravity (CG).

6. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-5. Airfoil shape.

7. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-6. Left aileron.

8. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-7. Vertical stabilizer and rudder.

9. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-8. Wing flaps.

10. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-9. Laminar flow.

11. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-10. Turbulent flow.

12. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-11. Total reaction.

13. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-12. Pressure around an airfoil.

14. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-13. Dynamic pressure increases with airspeed.

15. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-14. Dynamic pressure is greater in dense air.

16. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-15. Airflow can lift a flat plate (but not efficiently).

17. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-16. Examples of various airfoil shapes.

18. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-17. A cambered airfoil with internal structure.

19. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-18. More camber, more lift, less drag.

20. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-19. Mean camber line.

21. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-20. Camber.

22. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-21. Chord line.

23. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-22. The production of lift and drag.

24. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-23. The aerodynamic force acts through a point on the wing called the center of pressure.

25. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-24. Relative airflow (measured relative to the “free-stream” airflow).

26. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-25. Same angle of attack, but different pitch attitudes.

27. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-26. Same pitch attitude, but different angles of attack.

28. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-27. The angle-of-incidence is fixed during design and construction.

29. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-28. Coefficient of lift versus angle of attack; each angle of attack produces a particular C L value.

30. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-29. A cambered and a symmetrical airfoil.

31. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-30. Lift curve for a symmetrical airfoil.

32. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-31. The size of the aerodynamic force and the CP position change at various angles of attack.

33. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-32. The elevator keeps the attitude constant.

34. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-33. Contamination on the wings can seriously affect the lifting characteristics.

35. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-34. Low drag requires only low thrust to counteract it.

36. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-35. Skin friction and form drag.

37. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-36. A stalled wing increases form drag substantially.

38. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-37. Streamlining, especially behind the shape, greatly reduces form drag.

39. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-38. Streamlining reduces form drag.

40. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-39. Ice accretion on the airframe will increase drag.

41. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-40. Parasite drag increases with airspeed.

42. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-41. Induced drag increases as angle of attack increases.

43. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-42. The production of lift creates wingtip vortices and induced drag.

44. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-43. Induced drag is greatest at low speeds and high angles of attack.

45. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-44. High aspect ratio.

46. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-45. Total drag versus airspeed.

47. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-46. Aspect ratio.

48. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-47. Minimum drag speed.

49. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-48. Coefficient of drag versus angle of attack.

50. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-49. Design features that minimize induced drag.

51. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-50. C L versus angle of attack.

52. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-51. C D versus angle of attack.

53. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-52. Lift/drag ratio versus angle of attack.

54. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-53. Same lift at a different cost in total drag.

55. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-54. Lift/drag ratio versus angle of attack.

56. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-55. Typical flap installation—a Cessna wing-flap system.

57. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-56. Same airspeed: increased camber and/or wing flaps give higher lift.

58. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-57. Flaps lower the stall speed (and nose attitude).

59. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-58. Effect of flaps on lift/drag ratio.

60. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-59. Lowering the flaps can cause the airplane to balloon unless you simultaneously adjust the pitch attitude.

61. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-60. Extending the flaps may cause the nose to pitch.

62. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-61. A Fowler flap.

63. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-62. Slats and slots delay the stall.

64. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-63. Propeller terminology.

65. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-64. The speed of the blade section depends on the radius and RPM.

66. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-65. Each propeller blade-section follows its own path.

67. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-66. The propeller blade angle is made progressively larger from tip to hub to provide efficient angles of attack along its full length.

68. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-67. Forces on a propeller blade.

69. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-68. Fixed-pitch propeller—the angle of attack varies with forward speed and RPM.

70. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-69. A constant-speed propeller maintains an efficient angle of attack over a wide speed/RPM range.

71. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-70. Constant-speed propeller controls.

72. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-71. An offset fin helps counteract propeller-slipstream effect.

73. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-72. The down-going propeller blade produces more thrust when the airplane is in a nose-high attitude, causing P-factor.

74. © 2009 Aviation Supplies & Academics, Inc. All Rights Reserved. The Pilot’s Manual – Ground School Figure 1-73. Questions 68 to 70.