Andreas Maurer wrote:

An excellent point. Has anyone practiced spins with water ballast?
With just one tank full? In a Nimbus DM? With the pylon extended?

Ask Martin Heide, the current Schleicher chief designer.
His first task at Schleicher was the spin-testing of the first ASW-22.

When he did what you described (spin with only one full water tank),
the first 22 prototype broke apart inflight.

Hereupon this test was removed from the German LBA certification
requirement.

BTW: Martin was convinced that the 22 would break up in this kiind of
test.

Like I said, if you have enough money, and good parachutes and
are good at bailing out, you can train spins in whatever you
want, but the insurance company may eventually become suspicious :PPPPP