Optimum CG Range

On Dec 15, 10:42*am, Andy wrote:
On Dec 15, 6:52*am, wrote:

Gives adequate pitch authority to pull to max lift coefficient, thus
tightest turn. From my experience, this is usually about 75-80% aft in
manufacturer's approved range.
UH

It's not quite that simple though is it?

For the ASW-28, and probably other modern gliders, the "manufacturer's
approved CG range" is dependent on the glider mass. * Again for the
28, a cg position of 75-80 of approved range at min weight (315-321 mm
aft of root leading edge) will be behind the approved aft CG limit at
max gross wt (306mm).

I used to think that the change in aft cg limit with increasing mass
was to protect for the case where the tail tank fails to dump. *If
that is true then ASW 28 built without the optional tail tank would
not have the variable aft limit. *Do they?

Comments or other explanations of the variable aft limit?

Hank - Where is your 28 CG at max gross or at the max weight you fly
at if lower?

Andy (GY)

My glider is set up for about 75% dry- about 315mm. Water goes in tail
tank to maintain this position when water goes in wings. My manual
doesn't have variable limit but does suggest a dry position of 300-310
mm.
My glider is also set up to retain relationship of tail to main water
during dumping.
Only exception is ridge flying when I use less tail weight to unload
ship in gusts.
FWIW
UH