ORIGINAL: 3D_Junkie
The effect that you guys are talking about with the warbirds (or any single engine aircraft) is from P-factor not slipstream effects on the rudder.
As a mattor of fact, both P-factor and slipstream effects contribute to the yawing tendency during take-off.
P-Factor does not really come into play during 3-D flight since the forward motions are small and there is really not a difference in the angle-of-attack of the propeller during flight.
I could be wrong though, as I am sure someone will point out.
Some 3D maneuvers involves flying at high alpha, i.e., high angle of attack, at low speed. In those cases I would think that the P-factor does contribute significantly.