I noticed this today: http://www.newscientist.com/article.ns?id=dn7867

"In wind tunnel tests, Salmon stuck sections of plastic piezo-electric
film to wing segments. This film vibrates when an electrical signal is
applied, producing sound.

Tests using a barely audible sinusoidal tone of about 400 hertz showed
22% increase in lift, compared with a standard wing"

I've not found the entire paper but wonder: what thoughts or experience
does anyone have on this topic as it might relate to gliding?

Apart from the obvious about giving your aircraft a "tune up"

Cheers,
Neil
--
Christchurch, NZ