Referring to the ASK21 TM4b, publicly available on the
AS site. I see on page 4 : "By following the spin ballast
table a c.g. of approx. 406 mm (16 inch) is set in for the
flight."

As far as I can tell from other data, this is not the aft
limit. I believe the aft limit is 469mm.

The USAF spinning tests are well documented in the
technical note flight manual and discusses inertia effects
as well as just CG position effects. 406mm is aft enough.



At 23:32 13 September 2018, Andreas Maurer wrote:
On Mon, 10 Sep 2018 08:56:05 -0700 (PDT), krasw
wrote:

maanantai 10. syyskuuta 2018 16.54.53 UTC+3
kirjoitti:
Un-spinable? You might want to watch this and look
up the USAF report
conducted on the spin characteristics of the ASK-21.

https://www.youtube.com/watch?v=yXH6XDxQdPY

ASK21 is unspinable unless you equip with spin kit
designed to move cg
well aft of normal limits. Without this kit you cannot
spin 21.

One addition:
The spin weights put the CG to the normal aft limit, but
not beyond
it.
This is the same CG that you would have if a light pilot
flies without
a copilot.

With the spin weights the ASK-21 is an excellent spin
trainer.


Cheers
Andreas