I think this is really ignorant and misguided thinking. Yes, absolutely
the glider can damage the tug. The tail structure of most airplanes was
not designed to handle the load of a glider on tow. It was only
designed to handle aerodynamic and landing loads. Considering that the
breaking strength of a 5/8" rope is greater than the weight of the
towplane, it's not hard to imagine that it is certainly strong enough
to damage the tail. A 1000 lb glider can deliver well over 6000 lb of
pull before it's wings come off.

We have had an ongoing problem with stress cracking of the longerons
near the tail on our Super Cub towplane. It has been dsicovered from
time to time over the years during annual inspections because we have a
very good IA who knows how to look for this. And we tow with a 5/16"
poly rope, 1/4 the breaking strength of a 5/8" rope.

There have been a number of towplane upsets that would have resulted in
accidets had the tow rope not broken. The rope will not break when the
glider pulls the towplane's tail up, because the forces are not that
great. But after the upset, the forces are much greater, and if the
rope breaks, the towpilot has a chance to recover if there is enough
altitude remaining.

Most tow hook installations in the US are supposed to be placarded for
1200 lb breaking strength maximum. Most gliders also have maximum
breaking strength limits on their tow hooks as well (check your
manual). As has been pointed out in another thread, if you conduct
operations outside these limits, your insurance could deny coverage for
any resulting accident, especially since there will be a causal
relationship.

wrote:
A lot of the clubs here tow with thickish (5/8 inch and some 1/2inch)
poly and nylon ropes, without weak links, and pilots with years of
experience say that no load exerted by the glider can damage the tug -
and in the worst of cases even a 5/8 rope will break before damaging
the Tug (Most often a supercub)

Comments from knowlegable people please ---

Thanks and kind regards

JS