What are the forces on a tied down glider?

Just some facts, Eric. At Stead 2 gliders that were tied down at wing
tips and tail with 3/8" poly rope, broke all 3 ropes and performed a
near perfect half loop landing upside down after experiencing a
reported 100 knot wind (ships were tied down facing the wind).

At Minden 2 ships did much the same maneuver after experiencing about
the same wind (Winter storm frontal passage).

Raising the tail to get a negative angle of attack and locking the
spoilers open can go a long way in preventing the above OR, put it in
the box!
JJ