What other gliders are known to have this problem with
water or turbulent air? Seems I have heard that one
of the ASW series was similarly affected.

Pete

Pete,

I posted this about a month ago.
Sent: Thursday, April 29, 2004 7:14 PM
Subject: Pic 20's in the rain


Max,

Most gliders of that generation use the Wortmann FX 67 airfoil, which has
degraded performance when wet.
Some examples are :
Kestrel, DG-400, Pik-20, Nimbus 2, Lak-12, LS-3, Janus, HP-18, Jantar 2B

Apparently some are worse than others, I suppose this is due to the fact
that some use this profile on the wing roots only, with a different
profile
towards the wingtips (these being "better" or more "tolerant"), while some
use the FX-67 from root to tip. But it could be something else.

Apparently the laminar flow is disturbed very easily on this profile, so
not
only water, but bugs will degrade their performance as well.

Reading Dick Johnson's flight tests, especially some from the 70s, will
tell
you a little bit more about this.
If you go to this link (http://www.ssa.org/Magazines/Johnson.asp) and
scroll
down, there are 3 reports about the Pik-20, very illuminating.