Understanding Adverse Yaw | explained in simple terms. — Transcript

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1. 0:03an
2. 0:03airplane in straight and level flight
3. 0:06has a lift distribution pattern that
4. 0:08looks something like this
5. 0:10the lift generated by one wing is the
6. 0:13same as the lift generated by the other
7. 0:15wing
8. 0:17deflecting the right aileron down causes
9. 0:20an effective increase in the wing's
10. 0:22camber
11. 0:23and an increase in the effective angle
12. 0:25of attack
13. 0:26the lift from that section of the wing
14. 0:28increases
15. 0:30deflecting the left aileron up causes an
16. 0:33effective decrease in the wing's camber
17. 0:36and a decrease in the effective angle of
18. 0:38attack
19. 0:40the lift from that section of the wing
20. 0:42reduces
21. 0:44the primary effect of aileron
22. 0:46deflections is a roll
23. 0:50this is an approximate drag distribution
24. 0:52pattern
25. 0:54when the ailerons are deflected extra
26. 0:57drag is generated by both
27. 0:58wings however more drag is generated
28. 1:03by the down going aileron than the up
29. 1:05going aileron
30. 1:07this is induced drag and it is caused by
31. 1:10more lift required
32. 1:12on the right wing to help initiate the
33. 1:14roll
34. 1:19combining the lift and drag effects
35. 1:21together creates the undesirable
36. 1:24tendency
37. 1:25for the airplane to roll in one
38. 1:27direction but
39. 1:28you're in the opposite direction
40. 1:31this effect is called adverse yaw
41. 1:35this effect is most noticeable at low
42. 1:38speeds
43. 1:38and on airplanes with high aspect ratio
44. 1:42wings
45. 1:44there is another reason for the adverse
46. 1:46yaw that is not often mentioned
47. 1:50in straight and level flight both wings
48. 1:53encounter the relative airflow
49. 1:55head on but as the airplane rolls
50. 1:59and the left wing moves down a small
51. 2:02amount of additional airflow
52. 2:04strikes the wing from below
53. 2:07as the right wing moves up a small
54. 2:10amount of airflow strikes the wing from
55. 2:12above
56. 2:14and vice versa so as the airplane rolls
57. 2:19the relative airflow is deflected
58. 2:21slightly
59. 2:22up on the right wing and the relative
60. 2:25airflow is deflected slightly down
61. 2:28on the left wing as
62. 2:31lift always acts at right angles to the
63. 2:34relative airflow
64. 2:36the upward deflection of the relative
65. 2:38airflow on the right wing
66. 2:40causes lift to deflect backward
67. 2:45conversely as the left wing goes down
68. 2:49its relative airflow is deflected
69. 2:51downward
70. 2:52and its lift is deflected forward
71. 2:56the slight deflection of both lift
72. 2:58vectors
73. 3:00results in an adverse yaw moment to the
74. 3:02right
75. 3:04the adverse your moment is felt when the
76. 3:07airplane is rolling
77. 3:09and it stops when the airplane stops
78. 3:12rolling
79. 3:16adverse yaw can be prevented by using
80. 3:18the rudder to create a yawing moment
81. 3:21that helps to turn the airplane in the
82. 3:23correct direction
83. 3:25to remain coordinated
84. 3:29some aeroplanes incorporate design
85. 3:32features
86. 3:32to minimize the adverse yaw
87. 3:36one such feature is called differential
88. 3:39ailerons
89. 3:41by excessively deflecting the upward
90. 3:43aileron
91. 3:44drag is increased on the downgoing wing
92. 3:49this produces a desired your force in
93. 3:52the direction
94. 3:53of the turn
95. 4:03you