On Thursday, October 11, 2012 8:03:04 PM UTC-4, (unknown) wrote:
Weirdest thing today. On the grid, ready to takeoff. I had a highly experienced contest pilot hookup the small ring into my TOST hookup. When the towplane started rolling, after about 20 feet, it released uncommanded. I thought that it must have been the way it was hooked up, so we tried it again. Before the second attempt we did a very focused test and it seemed normal. Then on my second takeoff the same thing happened and I rolled to a stop again. We took the towrope and hooked up the ring just like we always do for a third time. Towplane engine shut off at this point. This time I pulled the rope with both hands as two guys were holding back on the sailplane and it disconnected just with my force. I now have the seat pan out, the instrument panel out and looking it over very thoroughly with a couple other pilots and see nothing. The cable looks normal, the sleeve looks normal, pulley system looks normal, the clamps at each end of the cable look fine. Essentially, everything associated with the release system looks brand new. The plan is to purchase a new TOST hook from Tim Mara and be done with it. I'm just writing this on here to inquire information regarding this from others. I am puzzled as to why this would have happened.

The last time I saw what you describe it turned out that the release cable was rusted inside the guide and just prevented the release from completely closing.
Pee in the belly is a bad thing.
Another case from the past was in 19's and 20's, guys would put the guide that supports the release and rudder pedal adjustment on the back of the bulhead they mount to and remove all the slack- Boinggggg!
Another couple experience points
UH