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?
The flight manual for my ASH 26 E also shows a reduction in the aft cg
limit above a certain mass, and a far greater change in the forward cg
limit over the entire mass range. It also shows the "Favorable CG range
for optimum straight flight performance" that is quite broad, about 80%
of the permissible range at full gross, and about 40% at the lowest
weight (100 pound pilot!). There is no chart for "optimum"
maneuverability in thermals, nor is there a tail tank.

It's a flapped ship, so I suspect it has a larger range than comparable
unflapped gliders, regardless of the criteria chosen.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly