CF in homebuilt aircraft

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#1

Nice Forum here,

I’m getting interested in CF for constructing non-structural parts for a home-built airplane mainly for weight savings. I’ve heard comments that pure CF parts are stiffer and more brittle than fiberglass. Should this be of concern to me? Seems like if I have to keep some fiberglass in the layup then I won’t be saving that much weight in the end.

Another question is the different types of resin and compatibility with fiberglass vs CF. We’re using Epoxy resins in the fiberglass layups. Any links to others doing similar work would be appreciated.

Thanks again for a great forum.

Bob

#2

Hello Bob,

CF will give you better stiffness than glass but it’s certainly not more brittle. The brittle factor is caused by the amount of resin used. When you’re resin rich, what you have is a heavy part with unsupported excess resin. Resin by itself is very brittle. So if you can control the cloth to resin ratio, you can certainly obtain higher strength to weight ratio compare to glass. Epoxy is the way to go, especially if you are building aircraft parts. A cheaper alternative would be vinyl ester, which is epoxy based.

Evan