Thrust line Angle
 

Is it right to say that the reason
for the ~2deg shift to the right of the thrust line on prop engine
is because of the P-Factor & Spiral Prop-Wash
(They both cause the nose left reaction)

Thrust line Angle
 

P-Factor yes, I don't agree that it is due to the spiral prop wash.

Thrust line Angle
 

But The Spiral PropWash heats
the ruder from the left side (Tail view)
and this affect creates a nose left reaction..

Thrust line Angle
 

The propeller was hits the right side elevator as well but doesn't roll! Sounds good, but I don't think so. Also do a slow pass then gun it, you will not see the effect as big as you do on the ground.

Thrust line Angle
 

Read the folowing article.
& watch the figures:


http://www.mindspring.com/~cramskill/propefct.htm