Pic 20's in the rain

At 00:12 30 April 2004, Matt wrote:
do they fall out of the sky when they get wet?

My best estimate (I flew them quite a lot in the late
70's/early 80's) was that in light rain best glide
went from near 1:40 to around 1:20, heavy rain or icing
could be worse. Difficult to be sure because some
(or nearly all) of the observed deterioration could
be sink. However, clean and dry they pretty much stayed
with the ASW 20, slightest hint of rain on the wings
and they dropped very rapidly away.

(Hank Nixon) wrote in message

I used to wash mine with very soapy water solution and let it dry on
front 1/3 of wing. This would allow water to wet out and flow off
wing. Good for about 10 minutes in the rain.
Good Luck UH

I have heard of people doing this. Has anyone tried that new car
washing stuff I have seen advertised on TV? Says it makes it so you
will never have to dry your car again. The water sheets up and runs
off. Dries without spotting. Sounds ideal for those of us flying the
ole 67K 150/170 sectioned gliders.

I have wanted to run a test by flying in a balast dump trail. Prepare
a test section of wing and fly in the dumped ballast. Do a visual
comparison of the standard and prepped sections. I have seen the
dreaded "wall of water" that forms on the top of the wing. Not sure
if it is more depressing to see it on a 15 meter wing, or a 22 meter
wing, though. ;-)

And I don't know if it was just the rain, or some sink, too. But I
was on a 40 mile or so final glide in my Zuni with an ASW-20. GPS
tracks showed neck and neck until I flew through a small shower. He
made it home, and I landed 6 miles short. He said he didn't get wet,
and looks to have been less than half a mile to my side and a bit
behind. A year or so previous, that same 20 was out ahead of me on a
final glide. He found sink and claimed picked up a headwind. Landed
about 6 miles short. I started for home a couple of turns after him
and a bit behind, and made it home. I guess what comes around goes
around.

Steve Leonard
Zuni II (15 meters worth of water spoiler)
604 (22 meters worth of water spoiler)

"Steve" wrote in message
om...
(Hank Nixon) wrote in message

I used to wash mine with very soapy water solution and let it dry on
front 1/3 of wing. This would allow water to wet out and flow off
wing. Good for about 10 minutes in the rain.
Good Luck UH

I have heard of people doing this. Has anyone tried that new car
washing stuff I have seen advertised on TV? Says it makes it so you
will never have to dry your car again. The water sheets up and runs
off. Dries without spotting. Sounds ideal for those of us flying the
ole 67K 150/170 sectioned gliders.


I would be careful to make sure that any such "miracle product' does not
contain silcone before you try it on your glider.

One thing I found flying my old PIK-20d in the rain and with bugs that
applies to any glider is to not fly too fast when the wings are
contaminated. Most speed to fly information is based on a clean polar and
it will be telling you to fly faster and faster as the sink becomes worse.
You will find the ground quickly. I found that if you just slow down in the
rain or with bugs that your achieved glide will be much better (but, of
course, not good).

If you have a vario with a "bugs" setting, and you think you know where to
set it, you can try that, too.
-Bob Korves

"Steve" wrote in message
om...
(Hank Nixon) wrote in message

I used to wash mine with very soapy water solution and let it dry on
front 1/3 of wing. This would allow water to wet out and flow off
wing. Good for about 10 minutes in the rain.
Good Luck UH

I have heard of people doing this. Has anyone tried that new car
washing stuff I have seen advertised on TV? Says it makes it so you
will never have to dry your car again. The water sheets up and runs
off. Dries without spotting. Sounds ideal for those of us flying the
ole 67K 150/170 sectioned gliders.

I have wanted to run a test by flying in a balast dump trail. Prepare
a test section of wing and fly in the dumped ballast. Do a visual
comparison of the standard and prepped sections. I have seen the
dreaded "wall of water" that forms on the top of the wing. Not sure
if it is more depressing to see it on a 15 meter wing, or a 22 meter
wing, though. ;-)

And I don't know if it was just the rain, or some sink, too. But I
was on a 40 mile or so final glide in my Zuni with an ASW-20. GPS
tracks showed neck and neck until I flew through a small shower. He
made it home, and I landed 6 miles short. He said he didn't get wet,
and looks to have been less than half a mile to my side and a bit
behind. A year or so previous, that same 20 was out ahead of me on a
final glide. He found sink and claimed picked up a headwind. Landed
about 6 miles short. I started for home a couple of turns after him
and a bit behind, and made it home. I guess what comes around goes
around.

Steve Leonard
Zuni II (15 meters worth of water spoiler)
604 (22 meters worth of water spoiler)

A fair bit of experimenting led me to think that flying
at normal best glide speed with about 2 degrees of
positive flap was least bad. I never tried to think
up theoretical explanations for that, but I'm reasonable
sure it was true.

At 00:06 03 May 2004, Bob Korves wrote:
One thing I found flying my old PIK-20d in the rain
and with bugs that
applies to any glider is to not fly too fast when the
wings are
contaminated. Most speed to fly information is based
on a clean polar and
it will be telling you to fly faster and faster as
the sink becomes worse.
You will find the ground quickly. I found that if
you just slow down in the
rain or with bugs that your achieved glide will be
much better (but, of
course, not good).

If you have a vario with a 'bugs' setting, and you
think you know where to
set it, you can try that, too.
-Bob Korves

'Steve' wrote in message
. com...
(Hank Nixon) wrote in message

I used to wash mine with very soapy water solution
and let it dry on
front 1/3 of wing. This would allow water to wet
out and flow off
wing. Good for about 10 minutes in the rain.
Good Luck UH

I have heard of people doing this. Has anyone tried
that new car
washing stuff I have seen advertised on TV? Says
it makes it so you
will never have to dry your car again. The water
sheets up and runs
off. Dries without spotting. Sounds ideal for those
of us flying the
ole 67K 150/170 sectioned gliders.

I have wanted to run a test by flying in a balast
dump trail. Prepare
a test section of wing and fly in the dumped ballast.
Do a visual
comparison of the standard and prepped sections.
I have seen the
dreaded 'wall of water' that forms on the top of the
wing. Not sure
if it is more depressing to see it on a 15 meter wing,
or a 22 meter
wing, though. ;-)

And I don't know if it was just the rain, or some
sink, too. But I
was on a 40 mile or so final glide in my Zuni with
an ASW-20. GPS
tracks showed neck and neck until I flew through a
small shower. He
made it home, and I landed 6 miles short. He said
he didn't get wet,
and looks to have been less than half a mile to my
side and a bit
behind. A year or so previous, that same 20 was out
ahead of me on a
final glide. He found sink and claimed picked up
a headwind. Landed
about 6 miles short. I started for home a couple
of turns after him
and a bit behind, and made it home. I guess what
comes around goes
around.

Steve Leonard
Zuni II (15 meters worth of water spoiler)
604 (22 meters worth of water spoiler)

"Matt" wrote:

do they fall out of the sky when they get wet?

Yes, just like the DG400, 200, LS-3 and many others.
Don't use strange products disigned to give long lasting lustre for
cars: they will produce much larger droplets on the wing surface, and
the problem will be worse.
Don't fly fast in the rain: lower your flaps and your speed as well.
The manual says that stall speed may increase, but any excess in speed
will be transfered to the water instantly: a big energy loss!
(a student has calculated the amount of energy needed to accelerate
100 grams of water from 0 to 60kts in a few seconds: it's about 3
times as much as the energy that would keep you flying level at the
same speed).

Water droplets will affect the tailplane too: you'll feel the stick
has different forces, generally it feels "dead". But it isn't, don't
worry.
Take care to avoid turbulence, as recovery from unusual attitudes will
become... scary!

I tried 40kts with landing (+15°) flaps on my 400, and was able to
avoid losing too much altitude. Stop for a few circles in any dry,
zero (or more) lift area, so you may later proceed gliding only when
the wings are nearly dry.

And generally, steer well clear of rain.

Aldo Cernezzi

Matt wrote:

do they fall out of the sky when they get wet?

Since I didn't see anyone mention it, I'll do so: taking off with rain
(or a lot of bugs) wings can also be troublesome. The manual on most
gliders cautions against it, and that caution is probably even more
important for a glider like the PIK 20.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Aldo Cernezzi wrote:
any excess in speed
will be transfered to the water instantly: a big energy loss!
(a student has calculated the amount of energy needed to accelerate
100 grams of water from 0 to 60kts in a few seconds: it's about 3
times as much as the energy that would keep you flying level at the
same speed).


I'm puzzled by the apparent assumptions here, why would any of the rain drops, other than that hitting the stagnation point on the leading edge, be accelerated to 60 Kts? It's much more likely that a high proportion of the mass of the rain drops would simply bounce off with very little momentum transfer. The rain which stuck, a much smaller proportion, may get accelerated to 60Kts, but there is only a limited amount which the wing could accommodate anyway. When I experimented with rain on the wings, I found the sink remained constant even though the speed increased, in which case my glide angle was getting better as I went faster. I must admit I didn't experiment with flaps, but I will, all these comments I've seen so far provide food for thought on how to get the best out of the glider in poor conditions.

Rgds,

Derrick.

Derrick Steed wrote:

Aldo Cernezzi wrote:
any excess in speed
will be transfered to the water instantly: a big energy loss!
(a student has calculated the amount of energy needed to accelerate
100 grams of water from 0 to 60kts in a few seconds: it's about 3
times as much as the energy that would keep you flying level at the
same speed).


I'm puzzled by the apparent assumptions here,

Dear Derrick,
clearly there are assumptions. But I have deliberately flown my 400
into rain, and kept watching the canopy and the wings, trying to
investigate the behaviour of water droplets.
A wing can get very little or a lot of water per time unit, depending
on many variables. Anyway, 100grams of water (= 0,1 liters) is just
half a drinking glass. Not that much, over 10,xx m2 of wing surface,
plus fuselage and tail. It definitely looked possible, from my
perspective in the cockpit, in anything more than light drizzle.

I have then tried to use my method (extremely slow flying, and parking
in dry, zero lift, before leaving for a glide) in competitions, and
could notice a very big advantage against those who raced to escape
from the rain. No matter if they were flying an 800!

all the above, is IMVHO.

Aldo Cernezzi
now dg600 flyier

Aldo Cernezzi wrote:
any excess in speed
will be transfered to the water instantly: a big energy loss!
(a student has calculated the amount of energy needed to accelerate
100 grams of water from 0 to 60kts in a few seconds: it's about 3
times as much as the energy that would keep you flying level at the
same speed).


I'm puzzled by the apparent assumptions here,

Dear Derrick,
clearly there are assumptions. But I have deliberately flown my 400
into rain, and kept watching the canopy and the wings, trying to
investigate the behaviour of water droplets.
A wing can get very little or a lot of water per time unit, depending
on many variables. Anyway, 100grams of water (= 0,1 liters) is just
half a drinking glass. Not that much, over 10,xx m2 of wing surface,
plus fuselage and tail. It definitely looked possible, from my
perspective in the cockpit, in anything more than light drizzle.

I have then tried to use my method (extremely slow flying, and parking
in dry, zero lift, before leaving for a glide) in competitions, and
could notice a very big advantage against those who raced to escape
from the rain. No matter if they were flying an 800!

all the above, is IMVHO.

Aldo Cernezzi
now dg600 flyier

I can assure you that although it maybe doesn't come across that way the are
lots of "V"'s in my "IMHO". I'm just curious about other the experience
other people have, to get the full story it's sometimes necessary to
challenge assumptions.

My reasoning was based on one not being able to "parking in the dry", but
instead having to get out of the wet, it's not clear what is the best option
for this. I am only too well aware of the bad effect the rain has, and I
have tried the wing both polished and unpolished (interestingly, the form of
the water droplets was different in the two instances - unpolished, they
stood like little spikes). The real worry I would have is taking off or
landing with the wings very wet - once when visiting a hill site I called
off the launch on a winch three times before giving up and calling it a day
because of passing rain shower wetting the wings (another pilot stole the
only dry launch possibility I had that day - I'll never forgive him for
that).
I hope to hear more experiences, it all goes into the melting pot.

Rgds,
Derrick.