Hi David

Thanks for the detailed explaination. It gives me a better understanding of roll and spin.

The plane I built has the following dimensions:
a) 40" wing span
b) 42" fuselage length
c) 12" chord, 16% thick symmetrical airfoil
d) CG at about 1/3 of the Chord (LE)

When full rudder is applied, the plane will yaw a little before one of the wing tip drops, resulting in a bank. In my other ARF fun-fly plane, the yaw is continous (without any wing tip dropping) and ended with a complete U-turn of the plane.

I wonder if the length of the fuselage is causing this? My ARF fun-fly plane has a shorter fuselage (as compared to wing span).

Anyway, I manage to reduce the problem by adding some aileron in the opposite direction of the rudder!

Thanks again!