1. Uncontrolled copy not subject to amendment Principles of Flight

2. Learning Outcome 2: Understand how the stability of an aeroplane is maintained in flight and how manoeuvrability is controlled Part 1

3. Principles of Flight Revision I Flyum Dan Winterland S Huttle H Copter B LoonsA Ship C Tower R Way A Bourne

4. Questions What is the force called that drives an aircraft forwards? Lift Weight Drag Thrust

5. Questions What is the force called that resists the forward motion of an aircraft? Lift Weight Drag Thrust

6. Questions If your speed is doubled, by how much would the Drag be increased? x2 x4 x6 x8

7. Questions If Thrust = Drag and Lift = Weight then the aircraft is: Climbing Flying Straight & Level and Accelerating Flying Straight & Level an Decelerating Flying Straight & Level at Constant Speed

8. Stability Objectives: 1.Identify the Axes of Rotation for an Aircraft. 2.Identify the Planes of Movement for an Aircraft. 3.Describe and Explain Stability in the 3 Planes of Movement. 4.Explain Dihedral and Anhedral and how they affect Stability.

9. Stability What would happen to this dart when thrown? What would happen now? Something is needed to “Stabilise” the Dart (Aircraft ). OW!!

10. Stability Centre of Gravity (CG) Airflow ‘Body’ Ahead of CG is Destabilising. ‘Body’ Behind CG is Stabilising.

11. Basic Stability Stable Unstable Neutral

12. Forms of stability Static - initial reaction Dynamic - subsequent reaction Stable Basic Stability

13. Stable Basic Stability Forms of stability Static - initial reaction Dynamic - subsequent reaction

14. Stable Basic Stability Forms of stability Static - initial reaction Dynamic - subsequent reaction

15. Stable Basic Stability Forms of stability Static - initial reaction Dynamic - subsequent reaction

16. Stable Basic Stability Forms of stability Static - initial reaction Dynamic - subsequent reaction

17. Application to Aircraft Static Stability Stable Neutral Unstable

18. Statically StableDynamic Stability Dynamically Neutral Dynamically Unstable Dynamically Stable Application to Aircraft

19. Pitch (Longitudinal) Planes of Stabilisation Longitudinal Axis Normal Axis Lateral Axis Yaw (Directional) Roll (Lateral)

20. Axis Plane Stability LongitudinalRollingLateral Stabilisation

21. Stability

22. Axis Plane Stability LongitudinalRollingLateral PitchingLongitudinal Stabilisation

23. Stability

24. Axis Plane Stability LongitudinalRollingLateral PitchingLongitudinal NormalYawingDirectional Stabilisation

25. Stability

27. Directional Stability

28. Flight Path CG Something causes the aircraft to yaw Lift Stabilising Influence of fin: 1.Value of Lift 2.Moment Arm Enhancement features: A large fin and/or a long moment arm

29. CofG Considerations An aft CofG requires a large Fin

30. MOD The strange case of the ever growing fins

32. Longitudinal Stability

33. Path Longitudinal Stability Lift Weight Flight To explain this stability, we assume that the CP and CG are coincident.

34. Longitudinal Stability Lift Weight Flight Path Something causes the nose to rise Lift Lift wings - Destabilising Lift tailplane - Stabilising Stabilising influence of Tailplane: Area x Moment Arm = Tail Volume

35. Lateral Stability

36. Weight Lateral Stability Lift Resultant Sideslip

37. Hdg Aircraft sideslips in this direction All design features for lateral stability rely on the fact that bank results in sideslip Lateral Stability

38. Lateral Stability Methods 1. Large Fin of high aspect ratio (a big tall fin). Lift from fin rolls wings level

39. 2. Dihedral: Due to new direction of relative airflow – lower wing has higher AoA than upper - more lift - tends to roll wings level. Lift Lateral Stability Methods

40. 3. Sweepback More Less More Higher Lower Span Chord Aspect Ratio Lift More Less LOW WING Lateral Stability Methods

41. 4. High wing Relative Airflow Air flow near wing roots affected by fuselage - Increases AoA on Low Wing -Decreases AoA on High Wing Less Lift More Lift Lateral Stability Methods

42. But too much Lateral Stability (High wing and Sweepback) very undesirable in fighter aircraft. Therefore anhedral to reduce the excess Lateral Stability Methods 1. High Fin. 3. Sweepback.4. High Mounted Wing 2. Dihedral.

43. Any Questions?

44. Stability Objectives: 1.Identify the Axes of Rotation for an Aircraft. 2.Identify the Planes of Movement for an Aircraft. 3.Describe and Explain Stability in the 3 Planes of Movement. 4.Explain Dihedral and Anhedral and how they affect Stability.

45. Questions What are the 3 planes of an aircraft’s movement? a. Pitching, Lateral and Rolling. b. Pitching, Rolling and Yawing. c. Yawing, Longitudinal and Rolling. d. Longitudinal, Lateral and Normal.

46. Questions Which one of the following will REDUCE Lateral Stability? Dihedral. A Large Fin. Sweepback. Anhedral.

47. Questions What are the 3 Axes about which an Aircraft can move? a. Pitching, Lateral and Longitudinal. b. Pitching, Rolling and Yawing. c. Yawing, Longitudinal and Normal. d. Longitudinal, Lateral and Normal.

48. Questions Which 3 Terms describe Static Stability? a. Stable, Neutral and Unstable. b. Stable, Rolling and Unstable. c. Yawing, Neutral and Stable. d. Neutral, Unstable and Pitching.