In article , Andy
Durbin writes

I have flown the last 15 or so years with aerotow on a cg hook. My new
ASW-28 has forward and CG hooks but I have never used the forward
hook.

First of all, if the manual says to not use the C.G. hook
for aerotow, I personally wouldn't try it, even once.
But that's just me.

Next, as a tow pilot, if I ever towed someone and found out
they used a CG hook not allowed by POH, I'd
have a lengthy discussion with the pilot. I'd explain why
I'm not interested in doing abnormal procedures without
being informed before the flight. I don't believe
I always must do everything recommended, but if I
decide not to, I MUST acknowledge that I am now a
test pilot, and have perhaps voided any insurance. I also
need to get the approval of anyone else put at greater risk
(a second pilot, the tug driver, etc.).

We had this happen when flying the Blanik L-13 without the
canopy. There was quite a bit of discussion and agreement
from all parties before doing this. In the end everything
worked out fine, but more importantly, everyone had input
and was comfortable that precautions and research had been
done. And boy was it FUN!

I would think glider CG might be an issue here.
In the past 15 years, you've flown using the CG hook of
a glider that has a certain CG and a certain, perhaps
fairly forward, loading. A new glider with a different
placement of the CG hook relative to the CG may
be a completely different ride. If you do try it, keep
meticulous records, and send a report to the manufacturer.
I bet they'd like to know, since maybe their test pilot
was too chicken to do it himself.

If you do decide to use the CG hook for an aerotow,
despite the voices here and the POH, at the very least
get the cooperation of the tow pilot, since it isn't just
you taking a risk. And if you can't find a towpilot to
agree, maybe that's a sign...

Another thought...is it possible to rig a towline in such a way
that it has TWO rings? So that one could release the nose
ring and then be on the belly ring? Could one then
launch (the super dangerous part) using the nose ring and
then release this and experiment using the belly ring up at
high altitude?

Hmmm...I guess not since they both release using the same
mechanism...but otherwise this seems to be a better way
to experiment than taking off on the CG hook.
I'd suspect that a factory test pilot who wanted to test both
hooks for aerotow might try something like this...with
two individual release knobs perhaps...

Of course all of this begs the question: if the glider
HAS a nose hook for aerotow, why not just use it?
But that certainly wouldn't encourage a nice armchair
discussion, right?