On Jul 3, 7:22 pm, Andreas Maurer wrote:
On Mon, 02 Jul 2007 20:29:48 -0700, Chip Bearden
wrote:

It's
interesting how two airplanes with identical performance when new had
such dramatically different lives.

Looks like the early LS-3s were flown in a climate with very little
rain....

Didn't the dramatic performance loss of the LS-3 in rain show up
immediately?

Bye
Andreas

Well, sort of. I got rained on many times when flying an annual
regional contest in Cordele, Georgia and noticed it. I can't say it
was the "falling out of the sky" feeling that PIK-20 owners complained
about, but performance suffered. In retrospect, it didn't seem any
worse than the few other gliders I've flown in rain (Libelle 201 and
ASW 24) even though I understand that airfoil does suffer more than
the newer airfoils from roughness.

I thought the LS-was somewhat less sensitive to rain after I contoured
the wings the first time and left them at 400 grit finish and I knew
other LS-3 drivers who did the same thing for the same reason. But
just before I sold it, I sanded it one last time and brought the
finish back up to a gloss. I might even have waxed it (not sure).
During my last contest with these polished wings, I flew into a
rainstorm flying the ridge in Pennsylvania. The sink rate did increase
but not as much as that of the DG-400 right behind me whose highly
experienced pilot complained he was forced to turn back to get out of
the rain and then use the engine to stay aloft. I eventually turned
back also but had no trouble staying aloft and waiting out the rain.
This was not exactly a scientific test but my impression was that
having polished wings hadn't really hurt and that the performance
degradation was significant but not unusual.

I concluded that the LS-3 probably wasn't much worse, if any, than the
other ships of its time when new. It's possible that it was more
sensitive after the flat spot over the spar cap developed due to
curing of the composite structure, making most other LS-3s more
vulnerable. Based on feedback from one PIK pilot, I also tended to use
more positive flap than normal when the wing was wet, which seemed to
help.

It's also possible that the LS-3's reputation developed more rapidly
in Europe due to the greater degree of bugs that can be deposited on
the wings. Bugs aren't generally a problem here in the U.S., even in
south Georgia in the summer (at altitude, that is; they're definitely
a serious problem on the ground!).

Chip Bearden
ASW 24 "JB"
USA