Build Thread: Gene's L3 Project

Looking great Gene. Are you going to fly this at the Ranch?

Thanks for the very detailed documentation Gene, looks very cool! I have a few simple novice questions.

For the rings, you used CF over Aramid (was it kevlar or nomex?) honeycomb. I've made similar structures with light solid woods before, but the honeycomb looks great. Where did you get the raw material, and how expensive was it?

How did you decide to use 2 layers of CF over the GLR panels? Is the GLR material not that stiff to start out, or was this mostly to hold the edging? Was sanding the panels enough to get the additional CF to adhere well?

Did you wrap the CF or glass over the edges of the fins to protect the balsa edging from dings?

By the way, thanks for the pictures of your jigs for cutting rings/bulkheads on the router table and disk sander. A nice simple way to trim CF parts, and add bevels.

Thanks, and keep up the great work!

For the rings, you used CF over Aramid (was it kevlar or nomex?) honeycomb. I've made similar structures with light solid woods before, but the honeycomb looks great. Where did you get the raw material, and how expensive was it?

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I got the raw Aramid core here: https://www.cstsales.com/products.html. It's around $9 to $15 / sq' dependin on thickness and quantity.

Key to using this core is you need to be carefull how you join it to the skins. I used a vacuum bag to make sure I have a good tight high quality bond to the carbon layers.

I used four layers of carbon on each side. I cut the weight over 3/8 ply by about 40%, and I can place the rings between two pieces of wood and it supports my 175lbs. They are incredibly strong, and super light.

How did you decide to use 2 layers of CF over the GLR panels? Is the GLR material not that stiff to start out, or was this mostly to hold the edging?

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I've worked with 6oz carbon for some time and I guess I just have a feel for it. I've also used a similar layup scheem on the Foly a Deux two stage project I did this last year. It's just seemed like a good place to start.

Regarding the GLR board, I think they sell finished board at the site listed above. GLR's price on it was actually pretty good. It's also very flat which I like. Most woods have some curvature that has to be pressed out. Not this stuff! The GLR board is reasonably stiff, but I wanted carbons strength and stiffness. There is no comparison to the original board and what I got from this combination. It rocks.

Was sanding the panels enough to get the additional CF to adhere well?

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I didn't see any issues with epoxy bonding. I did sand each side though but just to rough up and as part of finishing the balse edging.

Did you wrap the CF or glass over the edges of the fins to protect the balsa edging from dings?

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So I did the edging and shaping, and *then* I did the carbon lamination over the entire assembly. So the edges are integrated into the piece and not likely to seperate.

And ya, the router table with the centering jig works great for all kinds of parts. I don't know how I would get along without it.

Final tip - don't even try to cut your carbon laminate without carbide tools!

Thanks for the info!