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  • September 22, 2018, 03:30:31 PM

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Author Topic: Under-camber wing covering.  (Read 473 times)

Offline John Rist

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Under-camber wing covering.
« on: March 12, 2018, 08:47:38 PM »
How do you cover an under-camber wing on the bottom so the covering does not sag?  I am thinking of building a scale Eindecker wing.  ???
John Rist
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Offline Ken Culbertson

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Re: Under-camber wing covering.
« Reply #1 on: March 13, 2018, 05:56:15 PM »
Hi John. When I flew Nordic, they had under cambered wings and to keep the tissue attached, we used glue in Nitrate dope. Got it stuck to the ribs, then shrunk it using alcohol. NOT water. I have some glue and a bunch of Nitrate it you need some. Free. such a deal.  Ty H^^

Same here with a twist.  We put a couple of coats of thinned lacquer (which really is nitrate dope, just cheaper) on the frame to seal it.  Light sanding then wet the bottons of the ribs with full strength lacquer and stretched the tissue spanwise to remove the wrinkles.  Painted through the tissue on the LE & TE then pinned it to the workboard for 2 days.  You can shrink with alchohol but we found that if were careful pulling the tissue the final coats shrunk it enough and did not distort the shape as much.  We used a 1" rib spacing and one more trick.  We used a pinwheel to carefully put little holes in the tissue so when we put on the final coats it sunk in like little rivets.
I still have one wing set that is warp free and still fully attached.   The ship you are building was probably covered by light canvas and the undercamber was most likely sewn to the ribs with a canvas strip doped over the stitches.  I don't recommend trying to sew tissue.  My guess is you will use silk.  This will work well if you get the weave of the silk right but I would not use glue on silk.  It will not meld with the later coats unless you are putting caps on the bottom for scale. 

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Offline Ken Culbertson

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Re: Under-camber wing covering.
« Reply #2 on: March 13, 2018, 06:12:43 PM »
Hi John. When I flew Nordic, they had under cambered wings and to keep the tissue attached, we used glue in Nitrate dope. Got it stuck to the ribs, then shrunk it using alcohol. NOT water. I have some glue and a bunch of Nitrate it you need some. Free. such a deal.  Ty H^^
Ty:
How far back were your Nordic days?  I flew nearly daily with a now deceased gentleman named Don Chancey in the mid to late 60's.  He would be about 6 years your junior and was a world team member in the late 70's.   

Ken Culbertson
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Offline Ken Culbertson

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Re: Under-camber wing covering.
« Reply #3 on: March 13, 2018, 11:46:38 PM »
When I flew, 1971/79, it was still call A-1 and A-2. I flew a Top Kick, A Talon, Starstream, Jetstream, and a few others whose names I cannot recall.  I loved that big Talon. I remember when circle tow was the new rage, but I had been doing it for weeks simply because the damn thing would not release!! LL~ LL~ LL~ LL~ LL~ LL~ LL~ H^^
I knew of Don,but never met him.

Small world - I still have my A-2 Talon and I flew a Top Kick in A-1.  My last A-2 which disappeared in one of those Texas brick lifter thermals was an early version of Don's Hyperion.  We both eventually gave up Nordic in favor of Sailplanes.  No FF competition in Dallas but tons of Sailplane activity.  Don was one of the pioneers of Circle towing in the US.  I think he told me that he first saw the Russians doing it at worlds.  He became so good at it that he would do it with his sailplanes.
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Offline John Rist

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Re: Under-camber wing covering.
« Reply #4 on: March 16, 2018, 09:31:08 AM »
I found my Eindecker book.  Looking at the Eindecker wing it would be a tough build.  It is very thin and very under-camber.  The flying wires would have to be really functional!   n~
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Offline Paul Smith

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Re: Under-camber wing covering.
« Reply #5 on: March 17, 2018, 08:14:49 AM »
The undercamber wing is a real challenge and there's no reward.  In some classes of FF scale they give bonuses for undercamber and other difficult challenges.

With this subject, if you succeed, you merely avoid a downgrade.  If you take one of the many easy ways out, you get downgraded.

This is why some people just build Shoestrings.
Paul Smith


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