Think couples, not just forces
As far I see it ( in very simple terms as always) the error is you've drawn the force generated by the live engine and the force generated by the rudder as if they act both act directly/linearly through the C of G of the aircraft, whereas instead the forces are generating couples around the C of G. One is the couple generated by the asymmetry (clockwise in the case of your drawing), hopefully opposed by the (anticlockwise) couple generated by the rudder.
Standing by to be shot down or someone to draw a nice diagram!!!
Last edited by wiggy; 22nd Jul 2011 at 16:47.