Uncontrolled copy not subject to amendment

1. Uncontrolled copy not subject to amendment Principles of Flight

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

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

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

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

11. Basic Stability Stable Unstable Neutral

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

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

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

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

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

17. Application to Aircraft StaticStability Unstable Neutral Stable

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

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

20. Stabilisation AxisPlaneStability Longitudinal Rolling Lateral

21. Stability

22. Stabilisation AxisPlaneStability Longitudinal Rolling Lateral Lateral Pitching Longitudinal

23. Stability

24. Stabilisation AxisPlaneStability Longitudinal Rolling Lateral Lateral Pitching Longitudinal Normal Yawing Directional

25. Stability

27. DirectionalStability

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

29. CofG Considerations An aft CofG requires a large Fin

30. The strange case of the ever growing fins MOD

32. Longitudinal Stability

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

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

35. Lateral Stability

36. Lift Lift Weight Lateral Stability Resultant Sideslip

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

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

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

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

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

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

43. Any Questions?

44. Stability Objectives: • Identify the Axes of Rotation for an Aircraft. • Identify the Planes of Movement for an Aircraft. • 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.