On Thursday, April 30, 2015 at 1:15:07 PM UTC-5, Gav Goudie wrote:
With their permission I will gladly give you the contact details of at
least 2
tow pilots who have experienced just such a thing (unless it was their
imagination of course...)

I would love to hear the details: Where, what type of towplane, what kind of glider, how long was the towrope, what was the glider doing, pilot experience, result of the upset.

I've been towing on and off for 30 years, in everything from C-172s to Pawnees via Supercubs and have never been near a horizontal upset. Now, having my tail lifted by a glider kiting prior to release, that I've seen ;^)

Cheers,

Kirk