PPRuNe Forums - View Single Post - Why is Yaw 2nd effect of Roll? (and explain Trim)
Old 29th March 2007 | 12:18
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rondon9897
 
Joined: Jan 2007
Posts: 33
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From: West Midlands
s I said earlier, yaw (not surprisingly) occurs about the yaw axis, which is perpendicular to the other 2 axes and not related to where the horizon happens to be.

No such thing as a yaw axis its the normal or vertical axis

Yaw is not required in order for the aircraft to change heading EXCEPT when the wings are level.

A confusing statement which is technically incorrect, at slow speed adverse aileron yaw can momentarily produce a heading change in the opposite intended direction

A normal turn results from the horizontal component of the lift vector.
Yaw results from BANK when the vertical component of lift is insufficient to balance the weight - the aircraft sideslips and directional stability results in yaw.

You need to differentiate between into turn yaw and out of turn yaw. Into turn yaw will not occur if the height is maintained so again the above statement is not correct. The into turn yaw you are talking about occurs after the aircraft rolls and no corrective action is taken by the pilot.

You have also missed out;
The nose pitches down and eventually the result is spiral descent which is the most important point in the teaching of the further effects of aileron or rudder


Yaw results from ROLL because of differential drag caused by aileron deflection.

INCORRECT-- only out of turn adverse yaw is the product of aileron deflection. A non induced roll such as in turbulence will not produce adverse out of turn yaw if the ailerons remain neutral

Differential and frise ailerons reduce this but will only work optimally at a certain speed or angle of attack and (I believe) are typically optimised for cruise speed.

It is not possible to totally remove adverse aileron yaw hence to be correct an opposite rudder input is always required to offset this out of turn yaw

ASK CAPTAIN JON
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