Aerodynamics - PowerPoint Presentation

Slide1

Aerodynamics

Chapter 2

Stability and ControlSlide2

Figure 2-1.

Positive static stability

: tends to return to center.Slide3

Figure 2-2.

Neutral static stability

: no tendency to return.Slide4

Figure 2-3.

Negative static stability

: tends to diverge.Slide5

Figure 2-4. Damped oscillation—dynamically stable.Slide6

Figure 2-5. Undamped

oscillation—dynamically neutral.Slide7

Figure 2-6. Divergent oscillation—dynamically unstable.Slide8

Figure 2-7. Lift counteracts weight, thrust counteracts drag in straight-and-level flight

(moments neutralized by stabilizers and trim). Total weight includes download on the tail.Slide9

Figure 2-8. Thrust and drag form a pitching couple.Slide10

Figure 2-9. The lift–weight couple and the thrust–drag couple may be balanced.Slide11

Figure 2-10. Following a loss of thrust the lift–weight couple pitches the airplane nose-down.Slide12

Figure 2-11. The horizontal stabilizer provides the final balancing moment.Slide13

Figure 2-12. Propeller slipstream affects the force generated by the horizontal stabilizer.Slide14

Figure 2-13. Angular movement can occur about three axes.Slide15

Figure 2-14. Rolling about the longitudinal axis.Slide16

Figure 2-15. Pitching about the lateral axis.Slide17

Figure 2-16. Yawing about the vertical axis.Slide18

Figure 2-17. Longitudinal stability following an uninvited nose-up pitch.Slide19

Figure 2-18. Longitudinal stability following an uninvited nose-down pitch.Slide20

Figure 2-19. Longitudinal stability is provided by the tail feathers of a dart.Slide21

Figure 2-20. A forward CG—greater longitudinal stability.Slide22

Figure 2-21. Directional stability following an uninvited yaw.Slide23

Figure 2-22. Wing dihedral.Slide24

Figure 2-23. Dihedral corrects an uninvited roll.Slide25

Figure 2-24. Sweepback corrects uninvited roll.Slide26

Figure 2-25. High keel surfaces and a low CG correct uninvited roll.Slide27

Figure 2-26. A high wing tends to level the wings.Slide28

Figure 2-27. Roll causes yaw.Slide29

Figure 2-28. The CG must remain within the area bounded by the wheels.Slide30

Figure 2-29. A destabilizing crosswind.Slide31

Figure 2-30. Yaw causes roll.Slide32

Figure 2-31. The primary flight controls: elevator, ailerons, and rudder.Slide33

Figure 2-32. The elevator is the primary pitching control.Slide34

Figure 2-33. A butterfly tail (early Beech Bonanza model).Slide35

Figure 2-34. Separate horizontal stabilizer and elevator.Slide36

Figure 2-35. Stabilator

.Slide37

Figure 2-36. The ailerons–one up, one down–provide a rolling moment.Slide38

Figure 2-37. The rising wing has increased aileron drag, causing adverse yaw effect.Slide39

Figure 2-38. Differential ailerons reduce adverse yaw.Slide40

Figure 2-39.

Frise

-type ailerons equalize aileron drag and reduce adverse yaw.Slide41

Figure 2-40. Aileron/rudder interconnect can reduce adverse yaw.Slide42

Figure 2-41. Left rudder pressure—the nose yaws left.Slide43

Figure 2-42. Yaw is followed by roll.Slide44

Figure 2-43. The controls are more powerful with increased airflow.Slide45

Figure 2-44. The slipstream only affects the elevator and rudder.Slide46

Figure 2-45. Hinge moment at the control surface.Slide47

Figure 2-46. Inset hinge balance (at left) and horn balance (at right).Slide48

Figure 2-47. The balance tab.Slide49

Figure 2-48. Anti-balance tab on

stabilator

.Slide50

Figure 2-49. The anti-balance tab opposes further control deflection and provides feel.Slide51

Figure 2-50. An elevator trim tab.Slide52

Figure 2-51. A mass balance moves the control’s CG forward to prevent flutter.