Gary Emerson wrote:

I'm taking a wild guess here, a hypothesis only...

If you exceed VNE can you divide the failure causes into two families?
Structural and Flutter?

Ok, discount Flutter for the moment and consider only a structural failure.

If you are in moderate dive, the wings still have to support the weight
of the glider and therefore you have higher drag because the wing is at
some positive angle of attack.
However, if you are in a near zero G pushover, the wings are unloaded
vertically and therefore you are at a minimum drag condition from an AoA
standpoint. Then, if there is no flutter, you might get well beyond VNE
before something goes bang..

To go from level flight at 125 knots to 250 knots would require losing
over 2000 feet in this zero lift flight, much of which would vertical. I
have to wonder how a pilot could resist pulling back on the stick or
opening the spoilers for such a long distance! And how carefully he'd
have to fly to avoid G forces that would remove the wings; after all,
this maneuver isn't in the usual glider training syllabus.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA