Not an RV, but some may find the techniques transferable, and I'd love to see a bit more custom stuff in our fleet. These parts feature carbon's primary structural attribute,
stiffness. They're for an orphan Rans S-9 which wandered into my shop.
The standard canopy is not tall enough for me, and it's ugly as sin.
I decided to convert to an open cockpit sportster, a fun flying adjunct to the RV-8. At the regular 08A Sunday sunset meeting, one of the group sort of dared me to build it all in lightweight carbon, which was actually sensible, unlike most of our beer meeting ideas. The current plan will make both sections removable with just a few fasteners, quickly exposing the entire interior of the fuselage for inspection and maintenance.
Really stiff parts at lowest weight require that the top and bottom fiber elements be moved apart with a core element. Here I went with 1/8" honeycomb, similar to a Vans cowl. The best matrix application (the epoxy) would be to use pre-preg, but I was far too lazy to build the necessary oven, pre-preg is expensive, and cheap foam forms can't be baked anyway. The game was to see what I could do with a typical home shop wet layup, vacuum bagged.
First thing was to make two foam forms. They required a nice surface finish, in particular the turtledeck, because I want to leave the inside carbon pattern exposed. For whatever reason, folks just love the look.
Methods are just like the smaller parts in previous posts...shape foam, seal it, give it a smooth finish, wax, PVA, and do the layups.
Clean up, then lay out and cut all the materials.
Now for the fun part. Very rapidly, drape the first ply of 5.7 oz twill on the form, wet it out, then drape the honeycomb. Wet out the top ply of twill between plastic sheet to keep epoxy ratio reasonable, peel one side of the plastic, and drape it over the honeycomb. Add a perforated release ply, and a bleeder ply, then slide the whole thing into a big bag (furniture storage bags are huge), seal it, and apply vacuum.
The raw turtledeck shell, untrimmed, weighs a bit over two pounds. It would be a little lighter if made from prepreg, as there is some excess epoxy with the wet layup. However, the wetness means the interior finish is attractive with no other work. It is very stiff, and not being structural, more than strong enough to mount on the airplane with no interior ribs. It's just a big fairing. I will put a headrest bulkhead in the cockpit end.
The cockpit cover was made in a similar fashion, but with more carbon (5.7 twill and 12oz plain weave on the inside, 12 oz plain and a top sheet of 9 oz glass on the outside). It must support the windshield, and stand up to abuse when the pilot gets in and out.
Plenty more detail work to do, but here are the basic shells. I have two windshields, one the forward end of a broken RV-4 bubble, and this one, the aft end of an RV-8 bubble I found in the shop attic. I have not decided between them yet, but it should be a cute airplane either way. More later.
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