If any of you have ever worked with GLR (or other) glass or carbon skinned nomex honeycomb fin material, you know you need to make up leading, trailing, and in some cases tip edging. For subsonic rockets, a piece of hardwood dowel will suffice for a leading edge. For trailing edges and the leading edges on supersonic rockets, you need a razor bevel.
What I'm looking for is pre-made (or a process for making) carbon/epoxy or glass/epoxy pre-beveled edging for honeycomb fins. At the same time, I DO NOT want to take G-10, G-12 or some other variety of composite plate and grind it down to the desired bevel. While this is a known technology and one can readily make a jig to grind down such a bevel, that leaves two issues. 1) It is wasteful as hell to grind away perfectly good and expensive carbon or glass and epoxy. 2) The dust is not only highly nasty to your lungs, but it gets into everything and is also incredibly abrasive to your tools.
What I would prefer is formed or molded bevel strip that has the desired aspect ration and that requires nothing more than to trim it to length and bond it to the cut edge of the honeycomb, a light touch of sanding and then lay up the rest of your fabric to finishe the fins.
The question is, has anyone done this and created molds or some other method for laying up carbon or glass bevel strip? I'd hate to re-invent the wheel on this and I'd love to pick the brain of anyone who's investigated techniques for doing something like this. By the way, I'm looking to make strip on the order of 1/8" thick at the base and 5/8" or 3/4" high (5:1 or 6:1) and 1/4" thick at the base and 1.25" or 1.5" high.
Warren
I've been thinking of the same kind of project as well. My thoughts were to make a mold for the fin edges.
The idea was to cut strips of .062 G10 for the sidewalls of the mold.
I'd lay them next to each other along the long edge and place a tape "hinge" lengthwise along the joint, fold them back on themselves to whatever angle is needed and clamp them on a dowel or similar that would be the same as the fin width on the inside of the "V".
With it clamped in place, glue and glass the outside of the "V" shape.
Once it's cured, I would build a small box that you could hold this form and keep it solid. You could use epoxy or expandable foam to hold if firmly in place.
I was even thinking of placing a small diameter Carbon Fiber dowel in the mold to act as a leading edge. Also, the fiberglass or carbon rods you can get at "Into the Wind" in Boulder would be sweet for a trailing edge/glue joint for the newly formed fin edge.
Lef me know if you want to work on something like this together.
Ed
Hi Warren,
I too have looked for such V-shaped strips but the only thing I could find (pre-made) was the wood strips used in RC airplanes. I just opted for round carbon rods for my subsonic flights...
The only other idea that I thought of was a brass or aluminum T that you could attach to the edge of the fin then "fill in" to make the wedge.
Doug
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