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Building Tips and technical articles. => Building techniques => Topic started by: TDM on July 25, 2020, 09:39:21 AM
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For all of you who want to dabble in to composite constructions here is a link that explains step by step how to make composite wings fuselages etc.
These techniques are valid for whatever you want to build and can be applied in different parts of the model. You might be watching a hollow wing mold building and realize the same technique can be used for a fuselage for example. You night be watching making a compression molded wing and realize it could be used in a landing gear door build or some other part.
https://www.youtube.com/channel/UCWaPcbCQVYwQQ-zrQ5jpv7A
Resources
https://sweetcomposites.com/Kevlar.html Kevlar for hinges etc
https://www.sollercomposites.com/ for by axial sleves some unidirectional stuff
https://thayercraft.com/ for inexpensive fiberglass in bulk
https://www.easycomposites.co.uk/#!/ for carbon fiber at a reasonable price specially unidirectional carbon 100g, my number one weapon for spar reinforcement of spar material. Also some spread tow carbon and plain weave carbon.
https://cn-models.com/catalog/carboweave good resource for skin material.
https://www.r-g.de/en/home.html when all else fails these guise are more expensive but have good service. Here you can find the more rare elusive stuff not available elsewere.
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Awesome! Thanks!
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Here's the guy,
There's always a guy, he spent a short time at this Forum displaying his composite CL, "look ma, no balsa" model, and, if I remember, he has a build someplace in the Forum or a website with great photos.
I'll try to find it.
I don't remember the Country where he's from, but we did exchange a few emails. Because balsa was expensive in his country he opted for another building medium, as he said. Balsa is growing in price.
As you can see, he has great accomplished building skills, plus, obviously, he adapted to a totally different building medium.
His material methods are the use of blue or pink construction foam covered with two layers of fiberglass cloth, If I remember? I had interest because, although this sounds complicated, it isn't, and this method has been around for quite some time.
I actually made the cowling and the fuselage firewall radius areas for my Gee Bee Z using pink foam. I dissolved the foam using lacquer thinner but this builder keeps his foam in tact.
If I did try this method, I would most probably contact this builder and construct his identical model. Great looking model!
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It's hard to believe the price of balsa would be that much more than foam, fiberglass and epoxy.
I'm only repeating what that builder said. He may be from Hungry.
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You are thinking of Istvan Travnik. No balsa.
https://stunthanger.com/smf/building-techniques/the-bluefoam-model-or-how-to-build-a-stunt-plane-without-a-bit-of-balsa/
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He may be from Hungry.
How can someone be from Hungry? It is not anywhere on any map.
Keith
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How can someone be from Hungry? It is not anywhere on any map.
Keith
Hungary
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The master model builder using the foam method I'm referring to is our one and only,
Istvan Travnik.
Istvan has made many contributions to the Forum. Maybe he'll see this?
Here's a "cross section" of his work.
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Does he use epoxy - or perhaps some water based varnish with the glass cloth?
Glassed foam is a favorite building method with many R/C flyers.
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Does he use epoxy - or perhaps some water based varnish with the glass cloth?
Glassed foam is a favorite building method with many R/C flyers.
Istvan used glass cloth and Huntsman (CIBA) LY 5052 epoxy thinned with methanol over the blue foam.
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Almost all of Istvans plane can be made using the NXT Sport wing build techniques. You can find that stuff in the first thread link. Obviously you have to modify the techniques used for the fuse or wing construction. A great choose for resin is the MGS brand you can find at Aircraft Spruce.
Noteworthy is that Istvan is using closed cell foam which doesn't collapse during banging. Thinning resin with alcohol is not a good practice because it can alter the resins proprieties. The resin should be applied to the cloth and not the foam to reduce weight.
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Almost all of Istvans plane can be made using the NXT Sport wing build techniques. You can find that stuff in the first thread link. Obviously you have to modify the techniques used for the fuse or wing construction. A great choose for resin is the MGS brand you can find at Aircraft Spruce.
Noteworthy is that Istvan is using closed cell foam which doesn't collapse during banging. Thinning resin with alcohol is not a good practice because it can alter the resins proprieties. The resin should be applied to the cloth and not the foam to reduce weight.
There is nothing to be anxious, when we thin up a good, so-called "high energy" resin, by 20 or 30 % Methanol, in thin coat. First "painting" on sanded, pure bluefoam, is for stand up, and stabilize every small, or microscopic hairs on the surface. Next day it can be fully sanded, by 280 or 320 wet paper, and the surface will be absolute perfect (hard and smooth). Minimal weight of the resin remains on the surface. Next step we simply cover the surface basically by light glass weawe*, and "paint" again with thinned resin. The methanol does not harm the resin chemically, and since is very volatile, it is off in 5-10 minutes, hours before than the resin begins to polymerizing.
*the glass can be doubled on critical parts (e.g. nose of fuselage), or strengthened by some light, thin carbon (e.g. horizontal stab, "spar" in wing centre, etc. )
Istvan
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Happy New Year!! Any new technics or material choses in the foam model area?
Best, DennisT
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Happy New Year!! Any new technics or material choses in the foam model area?
Best, DennisT
Happy New Year to this nice company!
My answer is: YESSSSSS! S?P
Not everybody use blue/pink foam technology for IC driven big, heavy C/L stunt ships, and here is a technology for small, electric driven, or sailing planes, or flying toys for children.
When we want to get very light, not fuelproof models, we can substitute epoxy resin by genuine celluloid. (Nitrocellulose, scratched smelling camphor. ) It is soluble by methanol, so not harmful to polystyrene. When dries, will be very-very light, but strong.
Where can we found celluloid?
-old, 100 or 120 years old films gone already...
-old toothbrushes gone too...
-tabletennis balls banned after 2016...
-nowhere can be found old rulers, inking patterns...
But, in piano industry, between Ivory and Acrylic ages, the covering of white keys was celluloid, for almost 100 years.
So visit a piano restorer shop, ask / buy a pound from garbage, clean them, solve them in Methanol, and have fun! :)
Istvan