Eric Greenwell wrote in message ...

I think you forgot to account for the increasing load that pitching up
produces. Sure, the lever arm is reduced, but the glider is at a higher
angle of attack, increasing it's lift. This increases the force much
more than the lever arm is reduced, and the pitch up continues.

Good point. I have along train journey today, and will have a ponder
on this. I suspect the outcome will be along the lines of "the glider
has stick fixed stability in free flight anyway: the effect of the
added winch cable force is to increase this stability".

This eventually stabilizes with the glider in the normal nose high
attitude of a winch launch, but this is not a good attitude for
aerotowing! For a nose hook, the lever arm is much less to begin with,
and a small pitch up reduces it to zero - quite a different situation.

Agreed completely.

Ian