ORIGINAL: pimmnz
If I may offer a couple of observations...Major Tom, the Torque reaction of any engine/prop combination is always that provided by the engine, it cares not whether thrust is produced or not, if the stick in front is being rotated at an RPM then there will be torque, and it will be determined by the engine power and RPM.
Just to clarify: No reactive force = no counter-torque
That reactive force can be coming form drag solely or from drag plus acceleration or deceleration of the rotating body (propeller in this case).
A rotating body, at constant rotational speed and in vacuum will produce no counter-torque.
ORIGINAL: UStik
Precession of the helical propwash...............?
From
http://en.wikipedia.org/wiki/Precession:
"Precession is a change in the orientation of the rotation axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle (nutation) is constant. In physics, there are two types of precession: torque-free and torque-induced."