What are the forces on a tied down glider?

On Aug 14, 3:17*pm, jb92563 wrote:
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I use chain myself since it does not weaken much over time in the sun
and should be good way past what my glider could withstand.

At our airport a thunderstorm with downbursts came through about
this time last year. The C182 that was tied down with 1/4" aged
polyester broke all 3 strings and flipped on its back. (I'd feel worse
about this except that guy who tied it down, our local mechanic, had
listened to me give a speech on proper tiedown ropes at our airport
commission meeting not too many months before, and had chimed in with
support.)

And the C152 that was tied down with chains, in the lee of the FBO,
broke 2 of 3 chains and had damaged wing ends and tail.

The problem with chains is that you can't get all the slack out, and
in the turbulence of high surface winds, the variable lift generated
jerks the chains violently. Each sharp jerk generates powerful
transient tensions, and metal fatigue with repeated jerks is a very
real phenomenon. As our mechanic found out (yes, he too had faith in
chain until then).

Meanwhile, it obviously depends on the chain's metallurgy and
size...

Dan Johnson