I've worked with the stuff and plan on an M-powered bird that will fly with 1/8" Nomex honeycomb fin cores. Unfortunately I don't have a weight for you. I plan on putting beveled G10 strips for leading and trailing edges and adding a full layer of 5.6oz standard weave carbon on each side to the basic cores before mounting them on the airframe and then 1/3, 2/3, and full size tip to tip layers across the airframe.

I haven't seen 1/2" honeycomb material - I've just used the 1/8", 1/4" and 3/8" material Giant Leap sells. My L2 bird has fins made from the 1/8" material.

Unfortunately to make the upscale I will have to go around 1/2" to keep everything in scale. I may just use the thinner stuff and possibly loose points to keep this as light as possible.

Nothing is set in stone yet, I do have 3 other upscale ideas if this one gets out of hand.

How large of pieces do you need. I have some different assorted thickness of carbon fiber aluminum honeycomb.

Edward

I have some of the 1/2" and some 3/8" in the shop. These are the ones that Giant Leap sells.

I can go out and weigh them to be exact, but don't worry too much about the weights. The 1/2" is almost the same weight as the other dimensions. It's all pretty light stuff.

Im thinkin of a sheet around 4'x6' should do.
Right now im just throwin around ideas so at this point I dont need any just yet but thanks for lookin. When I get the actual plans scaled up Ill know more of total size.

A 4' x 6' sheet of what I have would probably be on the extreme high end of the price range 🙂

Edward

I found a 1/4" piece 24" X 48" online for $160. A little more for balsa core. I didn't see 1/2" thick but that is where I bought mine from.

Doug

Balsa end-grain is almost as light and considerably stronger from my understanding.

Another option to consider is foam-core fins. I built a fin can for someone a couple years ago made up of a skeleton-frame of foam-core board (cheap) with 2-part foam filling the spaces in the skeleton. The root edge and leading and trailing edges were done with basswood. The whole fin was skinned with carbon and glass and survived an L boost without a problem.

Very light and very stiff once the carbon was applied and far, far cheaper for materials cost than Nomex honeycomb. They definitely took more labor, but I've been thinking about doing this sort of thing again for a scale Nike-Smoke project I have in mind if I ever get around to moving on from my current fixation with MD altitude birds.

One final thought - in general, the thicker you make a stressed-skin construct like a foam or Nomex-core fin, the stronger and stiffer it is. Making a fin blank from a couple layers of foam-core may very well be stronger than plywood.

I finally went out to the shop and weighed the honeycomb I have in the fin material stash. I have a 1' x 3' piece of both 3/8" and 1/2".

3/8" weighs 703g.
1/2" weighs 475g.

Yes, that is correct - the 1/2" is lighter.

One thing about Nomex honeycomb panel. Weight depends a LOT on how it was made. If epoxy from the layup process fills some or all of the cells, it weighs a lot more than if it was properly laid up. I've seen homemade panel that didn't v-bag and the excess epoxy went INTO the honeycomb instead of out.

Since I have not seen this stuff, would 1/8" take the abuse of a full L motor? The actual fins would use the 3/8" but I will use the 1/8" for other parts.

Im thinkin Ill go with my other upscale plan. The one I want to do may get too expensive and could be very unstable at the scale I want to go with. I may even do a smaller scale of this then planned to test it.

would 1/8" take the abuse of a full L motor?

Well that all depends on the size ans shape of the fin, and the speed of the bird. If you have a long root and a small span (like the spars on an ARM), then you could use pretty pretty much anything. But a large span and a small root (ie an Mosquito) are another thing.

It's pretty good stuff. I also have some bare honeycomb core for making your own. As Warren poits out, that is pretty easy, but it's also very easy to add unneeded epoxy weight.

I'll be at the All Colorado Rocketry Dinner next week if you want me to bring the honeycomb for you to see for yourself.

I've flown 1/8" honeycomb fins on my L2 cert bird - standard trapezoidal planform ala Nike Smoke. Has something like 10 flights K and L on it and has fallen from 2K with an incomplete main deployment and bounced. No problem. That said, there are 3 layers of tip to tip of carbon/kevlar hybrid fabric, carbon and glass.

Warren

I wont be at the dinner but if anyone could bring a sample to the next launch that would be great.

I could always pick it up from anyone too.