ORIGINAL: WEDJ
ORIGINAL: snowman333
One more question ? what is coupling ?
Alan
When one control input axis creates a change of direction/heading on a different axis.
The most common example is that application of rudder only (yaw) in knife edge flight produces an (unwanted) change in roll or pitch, or both.
You are correct, but be careful when talking about axes. Changing an axis is MUCH different than moving about an axis.
For example, the elevator changes the longitudinal axis, but it makes the airplane pivot about the lateral axis.
A good example of coupling on the average sport airplane would be when you yaw the airplane (rudder) it typically rolls it in the same direction. You didn't touch the ailerons, but the airplane still rolled with use of the rudder. Our pattern airplanes don't (or shouldn't) exhibit that coupling.