R
Uli, has some actual data, from a load cell with telemetry, from our winch launches. Which should be much greater than anything you would see on tow. when winch launching the two areas of maximum rope stress are during the initial ground acceleration, and at the top when the winch can pull the the glider down while the glider is trying to go up. Only the first part of that is applicable to aerotow, and the initial winch pull is much greater than the relatively gentle acceleration of a tow plane.

If the rope does not break with the glider on or just off the ground, it shouldn't break during tow, unless the glider pilot does some unusual maneuvers behind the tow plane. The last time a student broke the rope on tow, I was relieved, because I could just land, and make it stop.

If you want the data e-mail me, and I'll hook you up with Uli.

SF