On 2/21/2014 3:23 PM, wrote:
Per Steve's comment that the only energy for the glider comes from the
towplane engine I have a comment which is in many ways a request for
enlightenment.
Snip...
I pushed forward on the stick, the glider began to react, as I
flew out of whatever it was caused the bobble, the glider sank fast towards
the concrete, so I (rationalizing) assume I moved the stick back to ease
the bump. The glider bounced off the concrete, not that hard but bounced.
The one thing I believe I truly remember is that there was a bit of a snake
in the rope -- ie some slack. The tow plane was of course accelerating. So
(rationalizing) as the glider bounces up I have at best neutral stick,
maybe a bit aft still, and the slack comes out of the rope and the glider
at this point began the early stage of a winch launch. I know that I did
two things quickly -- one was hit the release, the other was to get the
nose down.
Snip...
My point is that there can
be a hell of a lot of energy in the rope if for some reason it gains a bit
of slack and is then turned into an elastic band. For some strange reason
weak links sometimes do not bust when they might be expected to ...

Ropes indeed can store significant strain energy. Compared to poly ropes,
nylon rope is akin to a rubber band. Is anyone in the U.S. still using nylon
towropes behind their tugs? Real fun for beginning students and instructors...!

As to how that energy got into the rope...I'm with Steve.

Your written assessment sounds entirely plausible to me. Good job dealing with
your unwanted surprise.

Bob W.