Lest we forget "P" factor. Generally our planes are flying at a positive angle of attack, take-off, figting gravity, pulling toward the canopy in turns. Under these conditions we often find the downward moving blade (right side) at a higher angle of attack than the upward moving blade (left side). If you are unfamiliar) draw a little vector diagram with aircraft velocity you'll see it. This results in a torque force around the "Z" axis (yaw axis) requiring right thrust or right rudder to offset