Pik 20 D in rain
Milan Dolinar
hallo,
i“m flying a pik 20 d (D-5990). the plane is ok, as long as there is no
rain. does anybody no would could be done with this problems.
please dont“t say: do not fly in rain.
has anybody tried to use special polish?
Milan
Steven B. Wood
If the D is like a PIK 20B which I flew for years, rain is a problem.
Try the following. Slow down (between stall and best l/d) while rolling
out positive flaps until you hear the noise from the airflow seperation
over the wing diminish. This seems to wrap the flow down on the wing.
Play with this setting and the airspeed to optimize the performance.
This should reduce the problem. The new problem is that you are now
flying slow in the rain but at a better sink rate. The Pik 20-B could
not penetrate with rain drops on the wing. Avoidance was the main
tactic. Also, be real serious about finding a landing field if you
don't dry off quick.
Good luck.
Steve Wood - Atlanta
Robert Danewid
Milan Dolinar wrote:
> please dont=B4t say: do not fly in rain.
Milan
As far as I recall, when we evaluated the PIK-20 in the 70=B4s, it was
quite clear that the problem is the airfoil (Wortmann FX67), so I am
sorry, but the only advice there is is "do not fly in rain"
Dick Johnson did a lot of test flying with the PIK-20B. His reports were
published in Soaring and later the early ones (including the PIK-20
reports) were published in a booklet, "The Johnson Flight Tests". I
suppose you can order it from SSA.
Cheers
Robert Danewid
fi...@ibm.net
In <346549...@segelflyget.se>, on 11/08/97
at 09:25 PM, Robert Danewid <robert....@segelflyget.se> said:
>As far as I recall, when we evaluated the PIK-20 in the 70 s, it was
>quite clear that the problem is the airfoil (Wortmann FX67), so I am
>sorry, but the only advice there is is "do not fly in rain"
If the FX67-170/150 is so susceptible to laminar flow separations in the
rain (which I don't dispute), then why doesn't the Nimbus II (FX67-170)
and LAK-12 (FX67-170) have the same bad reputation as the PIK-20 for
flying in rain? The question begs to be asked.
I've got a PIK factory booklet that covers performance tuning issues such
as control gap sealing, etc.. It also has a section regarding rain. The
recommendation to help minimize the effects of rain other than not flying
in it was to wipe down the wings with a 50/50 solution of hand dishwashing
liquid and water. Let the solution dry for 10 minutes and buff with a soft
cloth. The seasoning here is to cut the surface tension of the rain to
promote sheeting of the rain on the wing surface.
-----------------------------------------------------------
Frank
fi...@ibm.net
PIK-20D
N3019M
-----------------------------------------------------------
Ian Johnston
Milan Dolinar (Dol...@t-online.de) wrote:
: rain. does anybody no would could be done with this problems.
An instructor I flew with recommended a good deep stall, claiming that this
let the rain run off. I offer this for what its worth. I suspect that, near
the ground, it's not worth much.
Ian
Shane's Signs, Inc.
The LAK-12 manual that came with my glider stated that the L/D
is cut in half when wet. And it would take about 7 minutes of flying to
dry the wing. I have flown the LAK-12 thru some light rain and did not
notice any negative effects. I fly 2-33'S alot so it would not bother me
very much to go from an L/D of 47 to 23.5.
Shane Neitzey
JNBearden
Milan Dolinar writes:
>i´m flying a pik 20 d (D-5990). the plane is ok, as long as there is no
>has anybody tried to use special polish?
An airline pilot competitor of mine used to say there were only three
things he was afraid of:
(i) his ex-wife's lawyer,
(ii) [I can't remember this one], and
(iii) a PIK in the rain.
I believe the PIK-20 gliders used the same popular Wortmann airfoil series
as the LS-3 (which I owned for many years) and many other 15M gliders of
similar vintage such as the Mosquito & Mini-Nimbus. These airfoils can be
sensitive to both pitch and roughness/waviness. Two thoughts, based on many
flights through rain:
- Lightly sanding the wing to a satin finish (400 or 600 grit) helps the
water "spread out" rather than forming beads or droplets which disrupt the
air flow. Wax has the opposite effect and probably should be avoided. Since
the PIKs had a painted finish, I assume the sanding/no wax approach would
be of less concern than for a more traditional polyester gel coated wing
(although my wings still looked beautiful after 13 years).
- Using more positive flap deflection than normal also seems to help.
Having said that, I'll admit that after I contoured my wings the last
time, I polished them up and waxed them in anticipation of sale, then got
caught in the rain on a ridge day. The airplane flew just fine. So much for
generalizations.
Chip Bearden
ASW-24 "JB"
TERRY LISANSKY
There is a wax that I see on those late-night infomercials that does not
bead water like most waxes do, it sheets it away. I haven't paid
attention so I can't remember the name. But, maybe this would be a
solution. You can get a glossy surface and water sheeting at the same
time...........Terry
--
Terry Lisansky - N3JJB http://udel.edu/~lisansky
Give me a fast ship........
For I intend to go in harms way.
Gar...@ameritech.net
In article <19971110035...@ladder02.news.aol.com>,
jnbe...@aol.com (JNBearden) wrote:
>
> Milan Dolinar writes:
> >i“m flying a pik 20 d (D-5990). the plane is ok, as long as there is no
> >rain. does anybody no would could be done with this problems.
> >please dont“t say: do not fly in rain.
> >has anybody tried to use special polish?
>
>
Waxes can be formulated to either bead or sheet water. Most automotive
waxes bead because people tend to think this is an indication of a good
wax job, but I have seen recent TV ads for waxes that sheet. Their pitch
is that sheeting reduces dried water spots.
-------------------==== Posted via Deja News ====-----------------------
http://www.dejanews.com/ Search, Read, Post to Usenet
bob gibbons
>>>>> "FI" == fivey <fi...@ibm.net> writes:
FI> In <346549...@segelflyget.se>, on 11/08/97 at 09:25 PM, Robert
FI> Danewid <robert....@segelflyget.se> said:
>> As far as I recall, when we evaluated the PIK-20 in the 70 s, it was
>> quite clear that the problem is the airfoil (Wortmann FX67), so I am
>> sorry, but the only advice there is is "do not fly in rain"
FI> If the FX67-170/150 is so susceptible to laminar flow separations in
FI> the rain (which I don't dispute), then why doesn't the Nimbus II
FI> (FX67-170) and LAK-12 (FX67-170) have the same bad reputation as the
FI> PIK-20 for flying in rain? The question begs to be asked.
As a long time PIK pilot I have certainly noticed the degradation in the
rain. As to whether the Nimbus II was as bad, I asked the old master
Dick Johnson this question. His reply was that the Nimbus II did have a
bad reputation for performance in the rain, just not as bad as the
PIK. Dick's explaination of why the PIK was worse is that the culprit
seems to be the thick versions of Wortmann's airfoils. For instance, the
17% thick FX67-170 was notable poorer in the rain than the thinner
FX67-150. Dick cited the Slingby Vega with the 15% section throughout that
did not have a bad reputation in the rain. On the other hand, the PIK
used the 17% version all the way out to the ailerons, where they
transitioned to a 15% section. The Nimbus II started at the root with
the 17% section but immediatly started a linear taper of the thickness
ratio. So, on the average, the PIK had a thicker Wortmann section than
did the Nimbus II, leading to degraded rain performance compared with
the Nimbus II. Dick cited the 604, with something like a 20% thick
Wortmann section as even worse than the PIK.
At any rate, I found this interesting.
Bob
--
Bob Gibbons Raytheon-TI Systems
Internet: Bob.G...@dseg.ti.com Dallas, TX
fi...@ibm.net
In <nqen4ncdh2.fsf@cronus>, on 11/11/97
>>>>>> "FI" == fivey <fi...@ibm.net> writes:
<snip>
>FI> If the FX67-170/150 is so susceptible to laminar flow separations in
>FI> the rain (which I don't dispute), then why doesn't the Nimbus II FI>
>(FX67-170) and LAK-12 (FX67-170) have the same bad reputation as the FI>
>PIK-20 for flying in rain? The question begs to be asked.
>As a long time PIK pilot I have certainly noticed the degradation in the
>rain. As to whether the Nimbus II was as bad, I asked the old master Dick
>Johnson this question. His reply was that the Nimbus II did have a bad
>reputation for performance in the rain, just not as bad as the PIK.
>Dick's explaination of why the PIK was worse is that the culprit seems to
>be the thick versions of Wortmann's airfoils.
<snip>
>The Nimbus II started at the root with the 17% section but
>immediatly started a linear taper of the thickness ratio. So, on the
>average, the PIK had a thicker Wortmann section than did the Nimbus II,
>leading to degraded rain performance compared with the Nimbus II.
<snip>
Now that makes sense to me.
So the second must ask question is which glider airfoil/glider is least
susceptible to performance degradation in rain?
Nick Leaton
My understanding about the performance of Pik D's in rain is that it is
the radius of curvature of the leading edge. A small radius leaves the
aerofoil vunerable to small inperfections - rain and bugs.
--
Nick
gus_st...@nymc.edu
In article <3468fc07$1$svirl$mr2...@news-s01.ny.us.ibm.net>,
fi...@ibm.net wrote:
>
> In <nqen4ncdh2.fsf@cronus>, on 11/11/97
> at 03:44 PM, r...@ti.com (bob gibbons) said:
>
> >>>>>> "FI" == fivey <fi...@ibm.net> writes:
> <snip>
> >FI> If the FX67-170/150 is so susceptible to laminar flow separations in
> >FI> the rain (which I don't dispute), then why doesn't the Nimbus II FI>
> >(FX67-170) and LAK-12 (FX67-170) have the same bad reputation as the FI>
> >PIK-20 for flying in rain? The question begs to be asked.
>
> >The Nimbus II started at the root with the 17% section but
> >immediatly started a linear taper of the thickness ratio. So, on the
> >average, the PIK had a thicker Wortmann section than did the Nimbus II,
> >leading to degraded rain performance compared with the Nimbus II.
> <snip>
>
> Now that makes sense to me.
>
> So the second must ask question is which glider airfoil/glider is least
> susceptible to performance degradation in rain?
>
> -----------------------------------------------------------
> Frank
> fi...@ibm.net
> PIK-20D
> N3019M
> -----------------------------------------------------------
SGS 2-33 ;-))
gus
Tor Olav Steine
Milan Dolinar wrote:
> hallo,
> i“m flying a pik 20 d (D-5990). the plane is ok, as long as there is no
> rain. does anybody no would could be done with this problems.
> please dont“t say: do not fly in rain.
> has anybody tried to use special polish?
The PIK is an excellent glider, only not in rain. The best answer I have
seen to explain this in this thread yet, is the thickness of the
airfoil.
The best way to reduce the problem, as we have found it (check the
trailer), is to sand the wings with 1200 paper, in lines 45 degrees to
either side of the longitudional. Do not rotate the sandpaper. This way
the water tends to spread out on the wings, rather than form bubbles.
We never polish the wings, since it causes bubbles of water on the
surface.
The wings have polyurethane paint, and do not have to be polished for
durability.
Why fly in ran, anyway :-)
--
Tor Olav Steine
_________________________________________________________________
[====> Ultrafast Vector Map Engine - http://www.flexim.com <====]
[_____ Beautiful glider for sale: http://home.sn.no/~tos _______]
Henryk Birecki
"Doug Haluza" <Xdha...@pipeline.com> wrote:
>We didn't dump the water until after we were clear of the rain. I wonder
>what would have happened if we dumped earlier. Is a heavier wing loading
>advantageous in rain?
Since at higher wing loadings you get better L/D at high speeds you
were probably better off keeping the ballast as you were flying
through sing. The 80kts you had to slow down to was most probably in
the speed range where the ballast paid off.
Happy flying
Henryk Birecki
Nilton O. Renno
I fly mine in the desert. It works, most of the time!
;-)
fi...@ibm.net
In <64j8ba$k64$1...@news.ccit.arizona.edu>, on 11/15/97
>I fly mine in the desert. It works, most of the time!
>;-)
There's always at least one SA in the crowd! :-)
Doug Haluza
bob gibbons wrote in message ...
>>>>>> "FI" == fivey <fi...@ibm.net> writes:
>
>FI> In <346549...@segelflyget.se>, on 11/08/97 at 09:25 PM, Robert
>FI> Danewid <robert....@segelflyget.se> said:
>
>>> As far as I recall, when we evaluated the PIK-20 in the 70 s, it was
>>> quite clear that the problem is the airfoil (Wortmann FX67), so I am
>>> sorry, but the only advice there is is "do not fly in rain"
>
>FI> If the FX67-170/150 is so susceptible to laminar flow separations in
>FI> the rain (which I don't dispute), then why doesn't the Nimbus II
>FI> (FX67-170) and LAK-12 (FX67-170) have the same bad reputation as the
>FI> PIK-20 for flying in rain? The question begs to be asked.
>
>As a long time PIK pilot I have certainly noticed the degradation in the
>rain. As to whether the Nimbus II was as bad, I asked the old master
>Dick Johnson this question. His reply was that the Nimbus II did have a
>bad reputation for performance in the rain, just not as bad as the
>PIK. Dick's explaination of why the PIK was worse is that the culprit
>seems to be the thick versions of Wortmann's airfoils. For instance, the
>17% thick FX67-170 was notable poorer in the rain than the thinner
>FX67-150. Dick cited the Slingby Vega with the 15% section throughout that
>did not have a bad reputation in the rain. On the other hand, the PIK
>used the 17% version all the way out to the ailerons, where they
>transitioned to a 15% section. The Nimbus II started at the root with
>the 17% section but immediatly started a linear taper of the thickness
>ratio. So, on the average, the PIK had a thicker Wortmann section than
>did the Nimbus II, leading to degraded rain performance compared with
>the Nimbus II. Dick cited the 604, with something like a 20% thick
>Wortmann section as even worse than the PIK.
Our Janus C has shares the aft fuselage, airfoil sections, and, I believe,
the airfoil section taper with the Nimbus II-C. We have only washed the
glider in flight once. We were on a long ridge and flight full of water
ballast when a rain shower crossed our path. We were on the return trip late
in the day, so we had no choice but to enter the rain to get home. We hit
moderate rain at Hyndmen and flew through rain in ridge lift about 20 miles
north to Bedford, PA. At Bedford we thermaled to cloud base (still in the
rain with full water) and jumped one ridge downwind to get home.
Before entering the rain we were flying 100 kts at -7 flaps. After entering
the rain we only had to slow to 80 kts. I didn't try playing with the flaps
to see if it made any difference. Fortunately both the wings and canopy had
just been treated with a polymer which caused the water to bead up,
otherwise we wouldn't have been able to see, the rain was that heavy (flight
visibility was about two miles, and we always had a landing field in sight).
The water was beading up and running back in streams across the wing.
Doug Haluza
JNBearden wrote in message
<19971110035...@ladder02.news.aol.com>...
[snip]
>
> - Lightly sanding the wing to a satin finish (400 or 600 grit) helps the
>water "spread out" rather than forming beads or droplets which disrupt the
>air flow. Wax has the opposite effect and probably should be avoided. Since
>the PIKs had a painted finish, I assume the sanding/no wax approach would
>be of less concern than for a more traditional polyester gel coated wing
>(although my wings still looked beautiful after 13 years).
Is there any objective evidence to support this? Although this explanation
seems intuitivly reasonable, one could also argue that waxing is better
(especially in heavier rain) since it allows the water to "go with the flow"
and pass over the wing without bunching up at the leading edge.
Doug Haluza
Henryk Birecki wrote in message <346c22a8...@hplntx.hpl.hp.com>...
>"Doug Haluza" <Xdha...@pipeline.com> wrote:
>
>>We didn't dump the water until after we were clear of the rain. I wonder
>>what would have happened if we dumped earlier. Is a heavier wing loading
>>advantageous in rain?
>
>
>Since at higher wing loadings you get better L/D at high speeds you
>were probably better off keeping the ballast as you were flying
>through sing. The 80kts you had to slow down to was most probably in
>the speed range where the ballast paid off.
>
No, we didn't fly 20 miles through sink! We were in ridge lift. The
reduction in speed from 100 to 80 knots was due to the performance penalty.
Doug Haluza
We didn't dump the water until after we were clear of the rain. I wonder
Andreas Maurer
On Tue, 11 Nov 97 19:44:53 -0500, fi...@ibm.net wrote:
>So the second must ask question is which glider airfoil/glider is least
>susceptible to performance degradation in rain?
The ASW-20 seeems very good in rain - Wortman FX 62-K131. I would
estimate the loss with a wet wing on less than 15 percent.
Bye
Andreas