wrote:
The "-21 "does not spin"????

I must have been hallucinating in the dozens I have done in them. You
might want to read the exhaustive and definitive USAF Test Pilot
School Report on the subject as well - written after someone at the
USAF Academy spun one into the ground.

The ASK21 does spin when the CofG ist aft of 400mm. But any halfways
normally grown pilot will put the CofG too much forward.

Since 1982 there has been TM #4 which describes a modification which
allows fit lead ballast to the tail and put the CofG in the spinning
range. For many years, only the USA and Switzerland had accepted this
TM, so the Germans and others had to resort to other gliders to train
spinning, which was pretty absurd given the aerobatic capabilities of
the ASK21. Only recently that TM became valid for the rest of Europe,
too. (I don't know about the rest of the world.)