Discus polar curve at high speeds

If "something goes bang" it is either because of a) flutter or b)
extreme drag forces when extending airbrakes at extreme speeds.

Which are the known incidents of gliders fluttering to bits?
(apparently Dirks parachuted from the DG-600 prototype after wing loss,
also almost loosing his eyeballs in the process...)

Karl

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

In article , Eric Greenwell wrote:
Gary Emerson wrote:

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.

You might also want to consider the twist in the wings.
Ever looked along your wing at high speed and noticed the tips bending down?

At really high speed you can twist your wings off. A blanik did that in
NZ a few years ago. One wing twisted off leading edge up, the other went
leading edge down.

--
Philip Plane _____
|
---------------( )---------------
Glider pilots have no visible means of support