Someone taught me a pretty effective way to put almost "all" the
gliders in a spin. It consist in just flying straight at a speed just a
little over the stall speed. Then use the ailerons only to slightly
bank the wings, say ten or fifteen degrees. At that moment if you push
the rudder on the side of the low wing you _will_ enter a spin.

I remember that during instruction we had to use the ASK13 for the
spins, because the Grob Twin Astir was not really spinning. Years after
I have then tried the Twin with this system, and geez down it goes...