steve, bone up on "P-torque" or "P-thrust" or more accurately "asymetrical
thrust". It is a common problem for aircraft with "conventional" landing gear
(meaning two wheels up front and one on the tail), and has been fully
understood since the early days of WWII.

Another P.S.

The change in direction of applied force from the torque of the
prop/shaft is only one part of the theory. The rest is the change in
the amout of paddle wheel effect as the angle changes as well as a
change in the amout of available thrust in the proper direction to
counteract the prop walk as the shaft angle changes.

I'm always willing to adjust the theory.

Steve