On 15 Mar, 05:45, Bob Cook wrote:
For purposes of analysis, the angle at which the tow rope meets the glider
is the angle to consider that THRUST is acting on the glider. *A rope can
only be in tension. *It cannot impart any rotational "moments" to the
glider.

Unless the hook is on the centreline and the tow rope is pulling
stright ahead, it certainly can apply a moment. Simplest case: low
down belly hook, pull straight ahead, pitch up.

Ian