I agree with Ed in most respects, and I think you need
to get a few facts right Denis.

Have you any reference for this affirmation ? THis
is a know issue on earlier delta wings, also in earlier
near-transsonic aircraft, but I don't know any glider
with such a problem.

Yes, as has already been mentioned the ASW20 has a
problem, where exceeding Vd can result in wing twist
that results in a terminal dive even with the stick
fully back. Not to mention what flutter can do anyway.



In most modern gliders you should be able to pull
6g+ without breaking any bits
off them.

Not at VNE !!!

Yes, I think Ed is probably right. Although the glider
will probably be a write-off after you land, because
the material will yield in highly stressed areas. Glider
wings are bloody strong, and are unlikely to snap,
but the reason you dont want to exceed the G-limits
every day is because bits will start to creep, and
your glider's structure will gradually deteriorate
and eventually fail, but as a One-off it is unlikely
to result in failure, particularly as the stalling
angle of the wing will limit the maximum g you can
pull below VNE. It will be pretty high, but is unlikely
to be more than 10g, and you shouldnt need to pull
this hard anyway. To be honest if it was a choice between
flutter, where bits like ailerons and elevator might
come off, and exceeding the G-limits where the wing
might be a write off but the plane will remain flyable
and be safe to land (or at least bail out of), I know
which I would choose.


The drag rise is not enough to avoid overspeeds. The
rise in drag
provided by *airbrakes* (not pulling too hard) is the
*only* way to
avoid either flutter (above VNE) or breaking the wings
(by overloading).

I believe that with the airbrakes open your safe positive
G-limit reduces to +2.5G. This is because you are forcing
most of the lift to be produced near the tip and thereby
increasing the wing bending moment at the root, and
there is also a hell of a shear force produced. God
knows what happens if you open them suddenly above
Va while pulling 3.5g but i suspect it would not be
pretty. (I also suspect that it may be this that caused
several big gliders to have wings come off in spin
recovery)

Ask an aerobatic pilot if you don't want to take my
word for it, but I believe their rule of thumb is that
it is always better to exceed the g-limits than to
exceed VNE, and that you should NEVER open the airbrakes
in an attempt to limit speed, because it has such a
small effect on drag and such a huge effect on the
g-limits.

Hope this in some way helps, though I think I am just
re-iterating what a lot of other people have already
said.

J.