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Jul 26, 2019, 08:26 AM
An itch?. Scratch build.
eflightray's Avatar
Just for reference, I have now covered one wing and decided to weigh it before covering the other one, (post #801) to compare the 'before and after'.

Uncovered - 560g -- 1lb 4oz

Covered - 700g -- 1lb 8 1/2oz

Quite a respectable increase, but considering each wing is 50" span with an inner chord of 17", (105" span Lancaster), and the surface strength has increased considerably, I'm not too worried.

Why do simple comments like white glue cause such a fuss .

Actually what I used to give it its correct name was Evo-Stik Resin W Wood Adhesive, it's white, same as my PVA. and which actually says Evo=Stik Waterproof Evo-Bond PVA. which inciently is the same color as my Gorilla Wood Glue. Should anyone care to get carried away yet more about chemical content.

.
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Jul 26, 2019, 09:44 AM
Space Coast USA
hoppy's Avatar
Thread OP
By commenting on the chemical composition, you do realize you now have joined the ranks of those who have gotten carried away.


Good data on the wing weights.
Jul 26, 2019, 12:31 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Pedantic.

Yes, I fit into that category too!
Jul 26, 2019, 04:18 PM
Entropy is happening!
Jim.Thompson's Avatar
Quote:
Originally Posted by eflightray
............................. I have now covered one wing .....................
Very good.
I am specifically interested in how straight your trailing edge turned out after the adhesive had dried.
Can you describe it? Or post a picture looking along the TE?
Jul 26, 2019, 06:10 PM
Foam is where the heart is
brett.c's Avatar
Hi, recently I retiled my bathroom and had some left over waterproof sealer https://www.dunlopdiy.com/component/...ive?Itemid=236
It looks like watered down PVA glue but has a more pungent smell.
I tried it on a reject xps foam wing ( hotwire cutting trial) and the results were quite good. The paper (brown) ended up quite smooth and tight with no ripples. Adhesion seemed as good if not better than the pva/glue mix.
I then soaked it in water and found that it wasn't quite as waterproof as I expected. The water did soak into the paper however there was no evidence of the paper lifting or bubbling. One of the problems I had with my earlier pva/water coverings was that the paper tended to bubble when painting it with water based paint. While the bubbles went away once the paint dried I am concerned about the effects when the humidity rises. As a precaution I have coated it wbpu.

My earlier paper covering trial plane is now complete and has been maidened. While heavy for its size at 670g it still flies like a dream and tracks very well. It feels more like a balsa build than a floppy foamy, and I put that down to added rigidity of the paper covering.
Jul 26, 2019, 10:26 PM
Space Coast USA
hoppy's Avatar
Thread OP
Titebond II with paper can be immersed in water with no problems. I gave it a 24hr soaking with no ill effects. The bubbling you experienced is the glue "ungluing" and the shrunk paper taking on its original dimensions, hence the bubble.

I don't think the brown paper shrinks like newsprint does, thus no bubbling when it gets wet and relaxes.
Jul 26, 2019, 11:38 PM
Foam is where the heart is
brett.c's Avatar
Quote:
Originally Posted by hoppy
The bubbling you experienced is the glue "ungluing" and the shrunk paper taking on its original dimensions, hence the bubble.
.
Thank you, that is my main concern, ie that these areas are no longer glued to the foam and the paper is merely "stretched" over them and will bubble up again once the weather turns humid. However, that is another 6 months away the plane may not last that long anyway
Oct 09, 2019, 03:20 PM
Short bursts, Don't waste ammo
RCAV8R1964's Avatar
Hoppy,
I may have missed it when I went through this thread but I have a question. Do you cover the fuselage, wing and tail pieces separately then assemble them or do you cover the plane after you have assembled it?
Oct 09, 2019, 03:53 PM
Space Coast USA
hoppy's Avatar
Thread OP
Cover each part separately. Trying to do it when assembled would be a tough project...
Oct 09, 2019, 03:59 PM
Short bursts, Don't waste ammo
RCAV8R1964's Avatar
Thanks!
Oct 09, 2019, 05:42 PM
Entropy is happening!
Jim.Thompson's Avatar

Trailing edges.


My only remaining concern about using this method to cover wings with is the result achieved at the trailing edge.
Is it possible to achieve a stable, straight and twist free control surface/ trailing edge with this?
Oct 10, 2019, 08:42 AM
Space Coast USA
hoppy's Avatar
Thread OP
No problem Jim if we are talking about something other than a razor edge. I wrap the bottom first with an overlap to the top of about a 1/2". Then while the bottom is still wet, wrap the top and overlap the bottom by about an 1". This gives you a double layer on the leading and trailing edges. Since both sides are covered at the same time the paper shrinking will be even and the foam stays straight.

Try it on a single piece of foam as a test. I never had a problem with single thickness foam pieces such as the rudder and elevator.
Oct 10, 2019, 08:45 AM
Registered User
Captain Dunsel's Avatar
Quote:
My only remaining concern about using this method to cover wings with is the result achieved at the trailing edge.
Is it possible to achieve a stable, straight and twist free control surface/ trailing edge with this?
I've done it, and I was pleased with how straight and strong the TE is on my test ship (Now over 2 years old). The problem I ran into is the vulnerability of the TE to 'hangar rash'. So, I've gone to a 1/8" sq. balsa TE on 200 to 400 sq. inch wings. They're much more resistant to handling bumps & dings, plus a bit easier to trim. I do that for the wing, rudder, and elevator TE's (most of my control surfaces are 1/4" foam, BTW, sanded down to 1/8" at the balsa edge).

Check out my plans in the "Plans for Scratchbuilt Foamies" thread for more info.

CD
Last edited by Captain Dunsel; Oct 10, 2019 at 08:54 AM.
Oct 10, 2019, 12:24 PM
Entropy is happening!
Jim.Thompson's Avatar
Thanks Hobby and CD.
I will look over on the other thread for your plans CD.
Oct 11, 2019, 07:29 AM
Registered User
Quote:
Originally Posted by brett.c
My earlier paper covering trial plane is now complete and has been maidened. While heavy for its size at 670g it still flies like a dream and tracks very well. It feels more like a balsa build than a floppy foamy, and I put that down to added rigidity of the paper covering.
OV-10 wing/booms/tail with a different fuselage? Interesting project!


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