In article
,
a wrote:

Reminds me of my first visit to the local wave camp three years ago.
Showed up really early in the morning, got the club two-seater (which we
had trailered over from our usual airport) out of the hangar, prepped it
for flight, and then let it sit out in the sun to clear the frost from
the wings.

As we're standing around talking and waiting, my instructor, who was
once head of the Navy Test Pilot School, turns to a younger club
instructor who I think had no non-glider experience and asks, "How much
frost on the wings starts to worry you?"

The younger instructor gave him an interesting look, and replied, "ANY
frost on the wings worries me...."

We waited for it all to sublime, then had a nice flight. And I learned
an interesting lesson on the different attitudes people can take. (And
I'm not saying either one was necessarily wrong, it's just interesting
how different the attitudes were and how clearly they were shaped by
their respective past experiences.)

Great big smilie...
I have a feeling that frost on the wings of a jet fighter wouldn't
have the same result as on the wings of a sailplane or even a Club
training machine.
Of course I'd like to be offered the chance to fly one of those there
fighters to see if I'm right. :-)

I have not taken off with frost on the wings, but have gotten into
icing conditions a couple of times. The airplane continued to fly well
enough, but looking at that stuff grow on the leading edges was not
fun. I would not want to have to land with any ice on the laminar flow
wings on my airplane, I have no idea when they'll stop flying! Now
having enough thrust to carry the stuff is a different story.

Certainly the thrust-to-weight ratio is a bit higher on the fighter.

I've never flown with frost on the wings (have flown through snow a
couple of times though, always entertaining) but I have flown through
rain and gotten the wings wet. Noticeably detracts from performance (and
it's amazing how much water stays on there), but add airspeed to
compensate and it's ok.

I had this happen on my checkride, actually. Didn't notice too much on
the wings, but we were flying around and suddenly I realized that we
were doing 50+kts and I had the stick at the back stop. (Normally it
should slow to under 40!) After some head scratching and worry, I
realized that the horizontal stabilizer was also wet, and the water was
destroying its performance. I shoved the trim all the way forward to put
the trim tab up and give me more authority, and all was well.

I imagine that light frost would be less destructive to performance than
rain, and so I wouldn't worry about it too much. On the other hand,
what's the harm in waiting for it to go away?

I should mention that the former test pilot has an enormous amount of
glider experience as well (he does about 1/3rd of all instruction in my
glider club, even though we have over a dozen instructors), and he
certainly knows what he's doing there, it's just that his overall
attitude to flying is a bit less nitpicky and a bit more cavalier than
the average instructor's.

Mike's glider with its 40 something to 1 glide slope would not need
much horsepower to keep it aloft, but I'd bet dew around the
stagnation point on the wings would have a bad effect.

I've only experienced wet wings in one glider (one of the club
two-seaters) but I've read some things about it, and the most striking
thing is how differently different airfoils will respond to being wet.
Apparently my type deals fairly well with it, but other gliders with
similar performance in normal flying can experience a drastic reduction
in performance after passing through rain. Aerodynamics is mysterious to
me....

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon