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Building Tips and technical articles. => Paint and finishing => Topic started by: bob branch on June 04, 2011, 05:54:17 PM
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I am going to be applying silkspan over a carbon fiber/epoxy structure. I plan on attaching it with dope but do not know if that will work or if it will pull off. Some of the edges will be on carbon tubes, some will be on carbon fiber plates. Anyone had any experience?
bob branch
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Ty is right , you are actually better off using carbon veil. And filling the weave with dope, and using a sandable primer. Carbon fiber, is not so porus, it does not soak up dope or paint like silk span. Essentially all you are trying to achieve is to fill the low spots in the weave as carbon does not swell. Plus carbon veil is far thinner than silk span yet much much tougher. This is where a picture is worth a thousand words. With carbon fiber dope is not so much a adhesive than a gap filler, if you get what I mean. It is not a dope to fiber bond like with silkspan but more a dope to dope bond with the fiber trapped between.
With carbon fiber you have to start thinking in terms of a matrix.
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Peter
Thanks for your input. But there is no wood in the structure whatsoever. It is 100% carbon fiber spaceframe. No solid structure either.
Thanks,
bob
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Peter
Thanks for your input. But there is no wood in the structure whatsoever. It is 100% carbon fiber spaceframe. No solid structure either.
Thanks,
bob
Hmmm,
Interesting, I have to ponder this. Acutally dependimg what you want to achieve, Monokote or some othwr film would be perfect foe this, as the heat activated ashesive works well, so long as you do not overheat the resins.
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Peter
That is the conclusion I have come up with as well. Since its electric power its not an issue. But the UV and heat exposure is. Colors will have to be very light. Like to be translucent but do not think I can get UV protection for the carbon that way. The ability of paint to block uv was the reason I was considering silkspan and paint.
bob
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I see your thoughts, black does soak up a UV and get hot. Carbon fiber it'self does not care about UV or heat. It is the binding resins. It all depends on the matrix as UV is actually used to cure some of the resins out there and those tolerate more UV than the sun can throw at it. You can always use chrome monokote, but you would probably need welders goggles to fly it on a sunny day. Actually on a electric stunter some chrome may actually look cool. :)
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Peter
Ever work with chrome monocote? We all should once in our life. I already did my once. On second thought, I have nothing against you at all. I'll recommend you pass on the experience.
bob
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Peter
Ever work with chrome monocote? We all should once in our life. I already did my once. On second thought, I have nothing against you at all. I'll recommend you pass on the experience.
bob
I have used the chrom stuff in the past, Really did not find it any different than any other color, at least it did not show through like the Gold Monokote, which ended up being not very opaque. Never covered an entire plane with the stuff, as it is really shiney. Mostly used in inset panels, accent areas, or where I wanted to give the impression of metal. (If you fine sandpaper chrome monocote with 800 grit straight in one direction you can imitate brushed aluminum or stainless really well) Actually now that I think of it, I did cover a face panel for a dish washer once with the stuff. Looked real good too.
Never use the self stick trim sheets as the glue used to suck on those, I cut trim from super monokote and Iron it on. Did a full camo forerunner once with kote.
If you look close at the attached picture you will see some chrome super monokote especially the really shiny part. (Pearl Blue, Transparent Blue, Gold, White, Metallic Blue, and Chrome!!!.
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Very nice Peter
bob H^^
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Is this similar to an article that was in a magazine some time ago? Need a picture. D>K
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I am going to be applying silkspan over a carbon fiber/epoxy structure. I plan on attaching it with dope but do not know if that will work or if it will pull off. Some of the edges will be on carbon tubes, some will be on carbon fiber plates. Anyone had any experience?
bob branch
I've made a bunch of carbon-epoxy stuff will all sorts of epoxy. It's pretty easy to get along with, except for the splinters, which you know about by now. I have put several different things on it for finish. The only chemical problem I had was with mold release residue on some wheel pants. It left pinholes in the finish. If the carbon tubes are the material that people sell for pushrods, I suspect (because of how it smells when cut) that they are made with polyester resin, which may be soluble in dope thinner.
Silkspan might tear at sharp corners, but I can't imagine any other problems with it. I put it over my carbon-epoxy-tube flap leading edges without incident. It stuck fine.
Although some epoxy used now in aircraft composites is UV sensitive, I haven't had any problems. I used some bare-composite landing gear for ten years, and it still held up to my landings. Heat could be an issue if you use low-Tg resin, keep it black, and leave it in the sun. Room-temperature-layup props change pitch when left out on hot, sunny days. I keep my spares in the cooler and cover the one on my plane with a rag. If your parts are made from 250-degree or higher prepreg, I wouldn't think they'd get hot enough to soften.
Phil Granderson may have used a carbon tube structure in his recent electric planes. He might have some wisdom on covering and finishing.
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Thanks Howard.
bob H^^