Originally Posted by
JPerrone
Rob2160: "At no stage do you need to hold rudder to compensate for the cross wind". That was what I was not sure about; I was thinking the best way to test this was.... to do it!!!
So, I'll try that, and keep in the back of my mind that I might have to just nudge the nose in the right direction, then return rudder to neutral.
There is a force-vector reason that you might need to hold rudder; but this might not prove to be true for a "real" model or airplane. With a cross wind, there's some sideways force. This is applied against the entire side of the craft. The total force behind the CG is trying to make the plane turn into the wind; the total force in front of the CG is trying to turn the plane away from the wind. If those forces equal; then there's no need to hold rudder.
The vertical stabilizer has a lot of area; the area behind the CG could be greater than the area in front; and the plane would essentially want to weathervane, ie , turn into the wind.
This is all theoretical of course. I would not be surprised if most airplane designs were such that the area of the airplane behind the CG is close to the area in front, so that the plane doesn't experience these imbalances
Regards
You can change heading with rudder, and when you release that rudder the plane will yaw slightly back to neutral.
You can also change heading with bank, using rudder only to balance the adverse yaw. This is actually a more efficient way of changing heading.
Yawing the body of the aircraft away from the flight path increases profile drag, this is why side slipping is a very good way of losing height quickly without gaining speed.
Using bank to change heading while keeping the aircraft in balance produces far less drag.
When you roll out on the desired heading, the plane will stay there. There is no weathercock effect in steady winds as the plane is moving with the wind.
Here is one way to understand it. You are flying in a commercial jet at 500 Mph. The air inside that jet is moving at 500 Mph relative to the ground. How much wind do you feel?
Planes fly all around the world every day, across jet streams over 150 mph that can be all crosswind for hours and never "hold rudder" to compensate.
Speed uses his rudder to change the heading of his plane in contests for a very specific reason, to avoid being down graded by the judges for banking.
If you don't have that limitation then turning by banking is always far more efficient.