Martin Gregorie wrote:
Bert Willing wrote:
Sorry Martin,

the 20 has full-span ailerons which aren't tiny by any means.
Negative flaps on initial ground roll is standard procedure for any
flapped ship, and if you do it with the 20, it is pretty difficult to
drop a wing.

Yes, I know the flaps deflect half as far as the ailerons, but there's
still very little bite below 30-35 kts even with a notch of reflex flap
and the ground roll felt very busy at first.

My ASW 20 C had plenty of "bite" by 20 knots - it was only the first 100
feet or so that might have a wing drop.


I had a wing drop or two among my first flights in my 20 - something I
never experienced on the club's Peg - or the Williams Soaring one
either. I don't recall much difference in the weather conditions during
those launches either - certainly nothing worth commenting on.

Some flapped gliders have a higher angle of attack when sitting on the
ground, compared to similar unflapped gliders. This can cause the tip to
stall more easily in the "neutral" flap position, but using negative
flap improves the situation. It also reduces the effects of crosswinds.

Why a higher angle of attack? One reason is to allow a slower touch down
speed with main and tail touching at the same time; another is a longer
gear extension can provide more pilot protection in an off field landing
(more clearance), and more protection in a very hard or crash landing
(more room to absorb energy).

--
Eric Greenwell - Washington State, USA
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* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org