Effect of rain on gliders in flight

[Michael[_7_]]

Hi all,

Beginner student here again. :)

The weather during my last training session was overcast with ceiling
at 2,500 ft. Right after our last tow for the day to 2,000.....after
the release and a turn or two....it started to rain, perhaps for just
5-10 seconds. I could see the rain drops on the canopy and see them
pushed back by the relative wind.

My instructor made no mention of it and I forgot to ask about it post
landing.

What are the implications about getting rained on in flight?
Obviously, if the ceiling is 2500 and overcast, this is primarily a
"training day." How should a glider pilot react to rain? How does it
affect the control of the aircraft?

How does one fly safely in the event or threat of rain?

--Michael

[Hellman]

Michael,

First, welcome to soaring. All of us were beginners once, and it's
great that you are asking questions. The things that come to mind with
rain:

Is there a possibility of lightning? If so, stay clear. Composite
ships are especially prone to lightning damage and I seem to remember
hearing of damage to the metal control linkages in one glider.

High performance gliders will suffer more loss of L/D in rain due to
their laminar flow airfoils -- which rain makes non-laminar flow, with
higher drag.

Will visibility stay VFR? Aside from seeing other traffic, is there
any danger of loss of spatial orientation?

A good general rule: If it feels dangerous, it probably is. At a
minimum, err on the side of believing that until you confirm
otherwise.

Martin

[Chris Reed[_2_]]

Rain on the wings will almost certainly increase the stall speed - by
how much depends on the particular airfoil. As a rule of thumb, older
wood & fabric or metal gliders suffer only a little degradation, early
glass (like my Open Cirrus) suffers quite a lot, newer glass suffers
something in between.

This means that if you are landing with wet wings you need a higher
approach speed to retain the same safety margin over the stall. Your
instructor will advise you (but maybe later in your training - now
you've got too much to think about just following the tow plane).

*Never* winch launch with wet wings, as this could lead to a stall and
spin off the wire. I wouldn't aerotow with anything more than mildly
damp wings either.

[[email protected]]

There is also an illusion caused by rain on the canopy that makes the
glider appear higher than it is - causing the pilot to flare higher
than normal. When you have rain on the windscreen, you should gently
fly it on; it is a surprise when you find that the height you expect
to touch the ground is not correct. Also, because you think you're
higher, you tend to fly a lower approach, so add a few feet for
obstacle clearance in rain.

There will also be a tendancy for the inside of the canopy to mist up
more, so open the vents.

[Berry[_2_]]

>
> What are the implications about getting rained on in flight?
> Obviously, if the ceiling is 2500 and overcast, this is primarily a
> "training day." How should a glider pilot react to rain? How does it
> affect the control of the aircraft?
>
> How does one fly safely in the event or threat of rain?
>
> --Michael


Most of the time, light rain is not going to be troublesome with
training flights as long as the visibility is good. However, take it
from one who knows: Even light rain can be accompanied by an occasional
downburst or or unexpected wind shear. You don't have to be actually
caught in the downburst itself. A downburst near the field can result in
a very rapid change in wind direction (shear). Not good if it catches
you on landing or takeoff. I was getting checked out in a glass 2-seater
for the first time. An instructor and I were doing takeoffs and landing
in a Grob. A little light rain had started falling. Almost now wind.
Ceiling was probably around 2000' but we were only towing to 800-1000.
We were on the takeoff run on what was to be my last dual flight that
day. We had just lifted off behind the Maul tug and airspeed was
indicating about 70 (don't remember if it was knots or mph).
Unexpectedly, the Maul plopped back down onto the runway, then we did
the same. I glanced at the airspeed and it was reading 40! Then I
noticed the trees tops whipping around. We were too close to the end of
the runway at that point to abort and the Maul went up over the low
trees at the end and we went with him. We immediately started descending
into the valley and picked up some speed. We got rolled around pretty
violently. The Maul driver got it more-or-less back under control,
managed to start climbing, and expressed his surprise that we had not
broken the tow rope in the turbulence. As we turned back towards the
airport, things calmed down. We had been caught in a reversal of wind
direction, apparently due to a downburst off the approach end of the
field.

[[email protected]]

On Apr 26, 9:36*pm, Michael > wrote:
> Hi all,
>
> Beginner student here again. *:)
>
> The weather during my last training session was overcast with ceiling
> at 2,500 ft. *Right after our last tow for the day to 2,000.....after
> the release and a turn or two....it started to rain, perhaps for just
> 5-10 seconds. *I could see the rain drops on the canopy and see them
> pushed back by the relative wind.
>
> My instructor made no mention of it and I forgot to ask about it post
> landing.
>
> What are the implications about getting rained on in flight?
> Obviously, if the ceiling is 2500 and overcast, this is primarily a
> "training day." *How should a glider pilot react to rain? *How does it
> affect the control of the aircraft?
>
> How does one fly safely in the event or threat of rain?
>
> --Michael

When wet, some airfoils, such as found on the Pic-20, can turn your
glider into a lawn dart... more like a hang glider than a slick glass
ship.... maybe 15:1. And, associated with some rain can be some
unpredictable and changing winds... strong down, strong up, headwind,
crosswind, downwind.

In my opinion, days that are overcast, and possibly rainy, should be
left to the ducks, not gliding... much less training gliding. We
might be eager to fly, and train, but haste can make waste... or
worse. Think safety. Fly safe.

19

[[email protected][_2_]]

Then again, if you are training in a 2-33, a little rain will probably
increase your performance by washing some of the bugs and dirt off!

Seriously, in a non-laminar wing (any metal trainer, pretty much),
especially if it hasn't been waxed recently (and who waxes a 2-33 or a
Lark!), light rain will have no aerodynamic effect. Biggest problem
will be reduced visibility through the canopy, and less braking action
if you land on grass.

Obviously, stay away from heavy rain showers or thunderstorms, but
pattern-bashing in a light, occasional drizzle beats watching birds
fly.

Good training, too.

Kirk

[Mike the Strike]

On Apr 27, 11:29*am, " >
wrote:
> Then again, if you are training in a 2-33, a little rain will probably
> increase your performance by washing some of the bugs and dirt off!
>
> Seriously, in a non-laminar wing (any metal trainer, pretty much),
> especially if it hasn't been waxed recently (and who waxes a 2-33 or a
> Lark!), light rain will have no aerodynamic effect. *Biggest problem
> will be reduced visibility through the canopy, and less braking action
> if you land on grass.
>
> Obviously, stay away from heavy rain showers or thunderstorms, but
> pattern-bashing in a light, occasional drizzle beats watching birds
> fly.
>
> Good training, too.
>
> Kirk

Kirk beat me too it! When you have an ugly crinkled metal wing
bristling with rivets, a few raindrops are hardly going to matter from
an aerodynamic perspective.

The most important consideration is the type of cloud overhead
producing the rain. Out here in the US west, there's a good chance
it'll be a shower cloud or thunderstorm that may produce downdrafts
and lightning - things to worry about a lot more than a few raindrops.

If you are in western Europe where most of the rain comes from
stratiform clouds, it's not so bad. Heck - if you live in some of the
countries with the worst climate (Britain for example), flying in the
rain is a necessary skill!

Mike

[[email protected]]

I also did some of my initial training in a 2-33 in the rain.
Naturally a light steady rain with good visibility, not associated
with unstable air. One thing nobody has mentioned is the sound. Even a
light rain sounds like someone is throwing BB's at the canopy.

I've also had to deal with rain while out on course on a cross-country
flight, and my glider has the same airfoil as a PIK-20. I've
thermalled to cloudbase more than once in a steady rain from lake-
effect cumulus (with full water ballast). I've also had to ridge soar
through heavier rain that ran across the wing in sheets (the boundary
layer water flow was mostly laiminar, the airflow not so much). And I
used a rain street to run upwind and get home late in the day. But
I've also landed out just a few miles from home when a summer thermal
street overdeveloped and started raining on me. So there is a
performance hit from rain, but it does not necessarily mean the end of
your soaring day. In fact, one promising soaring day almost looked
like a bust, until we realized the rain over the airport was falling
from a massive wave cloud--we towed upwind out of the rain, and had an
amazing wave flight.

On Apr 27, 4:40*pm, Mike the Strike > wrote:
> On Apr 27, 11:29*am, " >
> wrote:
>
>
>
>
>
> > Then again, if you are training in a 2-33, a little rain will probably
> > increase your performance by washing some of the bugs and dirt off!
>
> > Seriously, in a non-laminar wing (any metal trainer, pretty much),
> > especially if it hasn't been waxed recently (and who waxes a 2-33 or a
> > Lark!), light rain will have no aerodynamic effect. *Biggest problem
> > will be reduced visibility through the canopy, and less braking action
> > if you land on grass.
>
> > Obviously, stay away from heavy rain showers or thunderstorms, but
> > pattern-bashing in a light, occasional drizzle beats watching birds
> > fly.
>
> > Good training, too.
>
> > Kirk
>
> Kirk beat me too it! *When you have an ugly crinkled metal wing
> bristling with rivets, a few raindrops are hardly going to matter from
> an aerodynamic perspective.
>
> The most important consideration is the type of cloud overhead
> producing the rain. *Out here in the US west, there's a good chance
> it'll be a shower cloud or thunderstorm that may produce downdrafts
> and lightning - things to worry about a lot more than a few raindrops.
>
> If you are in western Europe where most of the rain comes from
> stratiform clouds, it's not so bad. *Heck - if you live in some of the
> countries with the worst climate (Britain for example), flying in the
> rain is a necessary skill!
>
> Mike-

[Ron Ogden]

At 00:02 28 April 2009, wrote:
>I also did some of my initial training in a 2-33 in the rain.
>Naturally a light steady rain with good visibility, not associated
>with unstable air. One thing nobody has mentioned is the sound. Even a
>light rain sounds like someone is throwing BB's at the canopy.
>
>I've also had to deal with rain while out on course on a cross-country
>flight, and my glider has the same airfoil as a PIK-20. I've
>thermalled to cloudbase more than once in a steady rain from lake-
>effect cumulus (with full water ballast). I've also had to ridge soar
>through heavier rain that ran across the wing in sheets (the boundary
>layer water flow was mostly laiminar, the airflow not so much). And I
>used a rain street to run upwind and get home late in the day. But
>I've also landed out just a few miles from home when a summer thermal
>street overdeveloped and started raining on me. So there is a
>performance hit from rain, but it does not necessarily mean the end of
>your soaring day. In fact, one promising soaring day almost looked
>like a bust, until we realized the rain over the airport was falling
>from a massive wave cloud--we towed upwind out of the rain, and had an
>amazing wave flight.
>
>On Apr 27, 4:40=A0pm, Mike the Strike wrote:
>> On Apr 27, 11:29=A0am, "
>> wrote:
>>
>>
>>
>>
>>
>> > Then again, if you are training in a 2-33, a little rain will
probably
>> > increase your performance by washing some of the bugs and dirt off!
>>
>> > Seriously, in a non-laminar wing (any metal trainer, pretty much),
>> > especially if it hasn't been waxed recently (and who waxes a 2-33 or
a
>> > Lark!), light rain will have no aerodynamic effect. =A0Biggest
problem
>> > will be reduced visibility through the canopy, and less braking
action
>> > if you land on grass.
>>
>> > Obviously, stay away from heavy rain showers or thunderstorms, but
>> > pattern-bashing in a light, occasional drizzle beats watching birds
>> > fly.
>>
>> > Good training, too.
>>
>> > Kirk
>>
>> Kirk beat me too it! =A0When you have an ugly crinkled metal wing
>> bristling with rivets, a few raindrops are hardly going to matter from
>> an aerodynamic perspective.
>>
>> The most important consideration is the type of cloud overhead
>> producing the rain. =A0Out here in the US west, there's a good chance
>> it'll be a shower cloud or thunderstorm that may produce downdrafts
>> and lightning - things to worry about a lot more than a few raindrops.
>>
>> If you are in western Europe where most of the rain comes from
>> stratiform clouds, it's not so bad. =A0Heck - if you live in some of
the
>> countries with the worst climate (Britain for example), flying in the
>> rain is a necessary skill!
>>
>> Mike-
>
>When you encounter precip you are likely to experience sink to one extent
or another because of the cooling effect of droplets or crystals that have
a relatively large surface area or just the natural effect of
precipitation entraining some local air as it descends. But as long as you
are dealing with the stable air type of precip--drizzle or flurries--its
unlikely to be noticeable

[bagmaker]

There is also an illusion caused by rain on the canopy that makes the
glider appear higher than it is - causing the pilot to flare higher
than normal. When you have rain on the windscreen, you should gently
fly it on; it is a surprise when you find that the height you expect
to touch the ground is not correct. Also, because you think you're
higher, you tend to fly a lower approach, so add a few feet for
obstacle clearance in rain.

There will also be a tendancy for the inside of the canopy to mist up
more, so open the vents.


Hey !

I have never heard of this wet canopy illusion, Dan, can you expand for me?
Why does this happen? Is it just from looking through the water like when looking into a pond?

thanks
bagger

[danlj]

On Apr 27, 9:41*pm, bagmaker >
wrote:
> -There is also an illusion caused by rain on the canopy that makes the
> glider appear higher than it is - causing the pilot to flare higher
> than normal.
>
> I have never heard of this wet canopy illusion...

Not one of the standard texbook visual illusions... which doesn't mean
it's not real.

The things I noticed when the dark cloud overhead opened up when I was
on downwind one day was that visibility was terrible AND the yaw
string stuck to the canopy AND there was terrific sink. I flew a very
small pattern...

DJ

[[email protected]]

Bagger, everything looks normal - until the ground isn't there when
you expect it to be; seems like you flare about 1-2 feet higher.
There is an abrupt arrival once your fully-held-off approach leaves
you will the flying qualities of a brick and too much altitude below
you. With the addition of a contaminated airfoil making stall speed
higher. carrying a couple of knots/mph/kph/furlongs per fortnight and
flying it on seems prudent.

Details mentioned at:
http://www.nappf.com/nappf_aero_medical.htm#Vision%20in%20Flight

From the Canadian Tansport Canada Aeronautical Information Manual
(AIM), Airmanship, Section 2.5:

"An error in vision can occur when flying in rain. The presence of
rain on the windscreen, in addition to causing poor visibility,
introduces a refraction error. This error is because of two things:
firstly, the reduced transparency of the rain-covered windscreen
causes the eye to see a horizon below the true one (because of the eye
response to the relative brightness of the upper bright part and the
lower dark part); and secondly, the shape and pattern of the ripples
formed on the windscreen, particularly on sloping ones, which cause
objects to appear lower. The error may be present as a result of one
or other of the two causes, or of both, in which case it is cumulative
and is of the order of about 5° in angle. Therefore, a hilltop or peak
1/2 NM ahead of an aircraft could appear to be approximately 260 ft
lower, (230 ft lower at 1/2 SM) than it actually is.

Pilots should remember this additional hazard when flying in
conditions of low visibility in rain and should maintain sufficient
altitude and take other precautions, as necessary, to allow for the
presence of this error. Also, pilots should ensure proper terrain
clearance during enroute flight and on final approach to landing. "

The AIM is now online, and a good reference for things like this.

Dan

[Geoff Vincent]

On Mon, 27 Apr 2009 11:58:30 +0100, Chris Reed
> wrote:

>
>*Never* winch launch with wet wings, as this could lead to a stall and
>spin off the wire. I wouldn't aerotow with anything more than mildly
>damp wings either.

My experience with wet wings (DG-300 and PIK 20B) when winch launching
is that the droplets disappear from the wing surface long before you
enter rotation and to all intents and purposes the launch is normal.
Both above-mentioned gliders had a well polished surface finish
though. I've also aerotowed on many occasions with wet wings -
"operations normal" at 60-65 kts airspeed.

In cruising flight there is a tendency to fly fast to "blow" the wings
free of water - this tends to be counter productive and I've settled
on 60-65 kts as the optimum for my PIK 20B. I estimate about a 20%
reduction in L/D with wet wings. Simply allow for a nominal 40:1
dropping to 32:1!

Geoff Vincent
Melbourne, Australia

[Chris Reed[_2_]]

Geoff Vincent wrote:
>
> My experience with wet wings (DG-300 and PIK 20B) when winch launching
> is that the droplets disappear from the wing surface long before you
> enter rotation and to all intents and purposes the launch is normal.
> Both above-mentioned gliders had a well polished surface finish
> though.

The British Gliding Association advice is never to winch launch with wet
wings. From memory of Steve Longland's book (effectively part II of the
BGA Instructor's Manual), your minimum winch speed is calculated as 1.5
x Vs (free flight), to allow a safe margin over the increased stall
speed on the winch caused by the weight of cable + pull of winch. If wet
wings increase the stall speed by, say, 15% (for my Open Cirrus it's
15-20%), the safe winch launch window is much smaller.

For my aircraft the normal launch window is 90-110 kph (50-59 kt). With
wet wings, the free flight stall speed rises from 60kph to 69kph (say 70
for ease of calculation), and 1.5 x this is 105kph. Max winch speed
remains the same, so I now have a safe window of only 5 kph (3 kt)!

It might be that the rain in the Southern hemisphere runs off wings
quicker, but I'm not taking chances on that if I get the opportunity to
fly there!

[Don Johnstone[_4_]]

The performance of some gliders is badly effected by wet wings. PIK 20,
Kestrel 17 and 19, Grob 103 spring to mind but there are others. The
Kestrel and PIK have a Wortman Section and the Grob an Eppler. All these
gliders suffer from very high sink with wet wings. Other gliders are not
so badly effected, the ASW17 would climb in rain. It very much depends on
the wing section as the ASW17 has a different Wortman Section.

Whatever the performance issues I would agree with the rule that a winch
launch should not be undertaken with wet wings, doing so could result in
you being served by undertakers.

At 15:11 29 April 2009, Chris Reed wrote:
>Geoff Vincent wrote:
>>
>> My experience with wet wings (DG-300 and PIK 20B) when winch launching
>> is that the droplets disappear from the wing surface long before you
>> enter rotation and to all intents and purposes the launch is normal.
>> Both above-mentioned gliders had a well polished surface finish
>> though.
>
>The British Gliding Association advice is never to winch launch with wet

>wings. From memory of Steve Longland's book (effectively part II of the

>BGA Instructor's Manual), your minimum winch speed is calculated as 1.5

>x Vs (free flight), to allow a safe margin over the increased stall
>speed on the winch caused by the weight of cable + pull of winch. If wet

>wings increase the stall speed by, say, 15% (for my Open Cirrus it's
>15-20%), the safe winch launch window is much smaller.
>
>For my aircraft the normal launch window is 90-110 kph (50-59 kt). With
>wet wings, the free flight stall speed rises from 60kph to 69kph (say 70

>for ease of calculation), and 1.5 x this is 105kph. Max winch speed
>remains the same, so I now have a safe window of only 5 kph (3 kt)!
>
>It might be that the rain in the Southern hemisphere runs off wings
>quicker, but I'm not taking chances on that if I get the opportunity to

>fly there!
>

[Bob Gibbons[_2_]]

On 30 Apr 2009 09:30:03 GMT, Don Johnstone >
wrote:

>The performance of some gliders is badly effected by wet wings. PIK 20,
>Kestrel 17 and 19, Grob 103 spring to mind but there are others. The
>Kestrel and PIK have a Wortman Section and the Grob an Eppler. All these
>gliders suffer from very high sink with wet wings. Other gliders are not
>so badly effected, the ASW17 would climb in rain. It very much depends on
>the wing section as the ASW17 has a different Wortman Section.
>
.... text deleted

It has been said a number of times before in this group, but probably
needs repeating for those new to the sport as ships like the PIK come
on the used market.
The impact of rain on the wings of the PIK is significant and easily
recognized, but based on my 2000+ hrs in a PIK20B, including multiple
500K+ flights, the effect is not dramatic. You will hear this effect
described by those with no experience in the type as "falling out of
the sky". This is NOT the case. When encountering rain in the PIK, you
can feel the separation as a low frequency vibration usually before
you can actually see the rain accumulation on the wing. As rain builds
up on the wings, the sink impact is probably about 20%, significant,
but not severe. I have continued flight many times penetrating though
rain showers. and, if the lift is strong enough to compensate for the
slight sink increase (less severe at slower climb airspeeds), the PIK
will climb perfectly well in the rain. I never noticed any effect in
landing during rain showers, though I would add 5 knots or so to my
landing speed.
That said, there is no arguing with the fact that the PIK (and others
with this airfoil) were more strongly effected by rain when compared
with the earlier non-laminar airfoil ships, and the later thin airfoil
ships. But this concern should not be a significant factor in the
decision of a pilot to consider one of these older, and often very
affordable sailplanes.
I sold my PIK over 10 years ago, but still would have no safety
concerns about flying the ship through the rain.

Bob

[Geoff Vincent]

On Thu, 30 Apr 2009 20:33:38 -0500, Bob Gibbons >
wrote:

>On 30 Apr 2009 09:30:03 GMT, Don Johnstone >
>wrote:
>
>>The performance of some gliders is badly effected by wet wings. PIK 20,
>>Kestrel 17 and 19, Grob 103 spring to mind but there are others. The
>>Kestrel and PIK have a Wortman Section and the Grob an Eppler. All these
>>gliders suffer from very high sink with wet wings. Other gliders are not
>>so badly effected, the ASW17 would climb in rain. It very much depends on
>>the wing section as the ASW17 has a different Wortman Section.
>>
>... text deleted
>
>It has been said a number of times before in this group, but probably
>needs repeating for those new to the sport as ships like the PIK come
>on the used market.
>The impact of rain on the wings of the PIK is significant and easily
>recognized, but based on my 2000+ hrs in a PIK20B, including multiple
>500K+ flights, the effect is not dramatic. You will hear this effect
>described by those with no experience in the type as "falling out of
>the sky". This is NOT the case. When encountering rain in the PIK, you
>can feel the separation as a low frequency vibration usually before
>you can actually see the rain accumulation on the wing. As rain builds
>up on the wings, the sink impact is probably about 20%, significant,
>but not severe. I have continued flight many times penetrating though
>rain showers. and, if the lift is strong enough to compensate for the
>slight sink increase (less severe at slower climb airspeeds), the PIK
>will climb perfectly well in the rain. I never noticed any effect in
>landing during rain showers, though I would add 5 knots or so to my
>landing speed.
>That said, there is no arguing with the fact that the PIK (and others
>with this airfoil) were more strongly effected by rain when compared
>with the earlier non-laminar airfoil ships, and the later thin airfoil
>ships. But this concern should not be a significant factor in the
>decision of a pilot to consider one of these older, and often very
>affordable sailplanes.
>I sold my PIK over 10 years ago, but still would have no safety
>concerns about flying the ship through the rain.
>
>Bob
>

Well spoken Bob - exactly my own experience, albeit with only 1600 hrs
in the PIK 20B. It is rarely acknowledged, but many other early glass
ships world-wide were equipped with the same Wortman FX 67-K- 170
(150) airfoil and suffered from performance degradation when the wings
were wet:

e.g. Kestrel 17/19, Glasflugel 604, Nimbus 2, Mini-Nimbus, Janus,
Caproni Calif, Open Jantar 1& 2, Mosquito, LS-2 (only one built, but
won a world championship - Reichmann, Australia 1974), LS-3, HP-18,
Zuni and several others.

It is such a pity that the PIK 20 seems to cop all the flak when the
subject of wet wings comes up! In almost all respects it's a great
aircraft.

Geoff V
Melbourne, Australia

[Wayne Paul]

Bob,

This is WAY off subject; however, your old Ka-6E
(http://www.soaridaho.com/photogallery/valley/Ka-6E.jpg) is sitting in its'
trailer in a hangar here in Idaho. I sold it to the current owner a little
over 10 years ago. He has never flown it and seems to have no desire to
sale it.

Wayne
HP-14 "6F"
http://www.soaridaho.com/

"Bob Gibbons" > wrote in message
...
> On 30 Apr 2009 09:30:03 GMT, Don Johnstone >
> wrote:
>
>>The performance of some gliders is badly effected by wet wings. PIK 20,
>>Kestrel 17 and 19, Grob 103 spring to mind but there are others. The
>>Kestrel and PIK have a Wortman Section and the Grob an Eppler. All these
>>gliders suffer from very high sink with wet wings. Other gliders are not
>>so badly effected, the ASW17 would climb in rain. It very much depends on
>>the wing section as the ASW17 has a different Wortman Section.
>>
> ... text deleted
>
> It has been said a number of times before in this group, but probably
> needs repeating for those new to the sport as ships like the PIK come
> on the used market.
> The impact of rain on the wings of the PIK is significant and easily
> recognized, but based on my 2000+ hrs in a PIK20B, including multiple
> 500K+ flights, the effect is not dramatic. You will hear this effect
> described by those with no experience in the type as "falling out of
> the sky". This is NOT the case. When encountering rain in the PIK, you
> can feel the separation as a low frequency vibration usually before
> you can actually see the rain accumulation on the wing. As rain builds
> up on the wings, the sink impact is probably about 20%, significant,
> but not severe. I have continued flight many times penetrating though
> rain showers. and, if the lift is strong enough to compensate for the
> slight sink increase (less severe at slower climb airspeeds), the PIK
> will climb perfectly well in the rain. I never noticed any effect in
> landing during rain showers, though I would add 5 knots or so to my
> landing speed.
> That said, there is no arguing with the fact that the PIK (and others
> with this airfoil) were more strongly effected by rain when compared
> with the earlier non-laminar airfoil ships, and the later thin airfoil
> ships. But this concern should not be a significant factor in the
> decision of a pilot to consider one of these older, and often very
> affordable sailplanes.
> I sold my PIK over 10 years ago, but still would have no safety
> concerns about flying the ship through the rain.
>
> Bob
>

[vontresc]

On May 1, 9:29*am, "Wayne Paul" > wrote:
> Bob,
>
> This is WAY off subject; however, your old Ka-6E
> (http://www.soaridaho.com/photogallery/valley/Ka-6E.jpg) is sitting in its'
> trailer in a hangar here in Idaho. *I sold it to the current owner a little
> over 10 years ago. *He has never flown it and seems to have no desire to
> sale it.
>
> Wayne
> HP-14 "6F"http://www.soaridaho.com/
>
> "Bob Gibbons" > wrote in message
>
> ...
>
>
>
> > On 30 Apr 2009 09:30:03 GMT, Don Johnstone >
> > wrote:
>
> >>The performance of some gliders is badly effected by wet wings. PIK 20,
> >>Kestrel 17 and 19, Grob 103 spring to mind but there are others. The
> >>Kestrel and PIK have a *Wortman Section and the Grob an Eppler. All these
> >>gliders suffer from very high sink with wet wings. Other gliders are not
> >>so badly effected, the ASW17 would climb in rain. It very much depends on
> >>the wing section as the ASW17 has a different Wortman Section.
>
> > ... text deleted
>
> > It has been said a number of times before in this group, but probably
> > needs repeating for those new to the sport as ships like the PIK come
> > on the used market.
> > The impact of rain on the wings of the PIK is significant and easily
> > recognized, but based on my 2000+ hrs in a PIK20B, including multiple
> > 500K+ flights, the effect is not dramatic. You will hear this effect
> > described by those with no experience in the type as "falling out of
> > the sky". This is NOT the case. When encountering rain in the PIK, you
> > can feel the separation as a low frequency vibration usually before
> > you can actually see the rain accumulation on the wing. As rain builds
> > up on the wings, the sink impact is probably about 20%, significant,
> > but not severe. I have continued flight many times penetrating though
> > rain showers. and, *if the lift is strong enough to compensate for the
> > slight sink increase (less severe at slower climb airspeeds), the PIK
> > will climb perfectly well in the rain. I never noticed any effect in
> > landing during rain showers, though I would add 5 knots or so to my
> > landing speed.
> > That said, there is no arguing with the fact that the PIK (and others
> > with this airfoil) were more strongly effected by rain when compared
> > with the earlier non-laminar airfoil ships, and the later thin airfoil
> > ships. But this concern should not be a significant factor in the
> > decision of a pilot to consider one of these older, and often very
> > affordable sailplanes.
> > I sold my PIK over 10 years ago, but still would have no safety
> > concerns about flying the ship through the rain.
>
> > Bob- Hide quoted text -
>
> - Show quoted text -

That is really sad. A Ka-6 would make some beginning glider pilot very
happy. I sure do love mine....

Pete