RocketFeller
Well-Known Member
- Joined
- Sep 15, 2009
- Messages
- 1,185
- Reaction score
- 74
I have spent a lot of time trying to figure out exactly how to build the fins for our 4.9x upscale Dragonfly.
In the end we have decided to go with 1/2" end-grain balsa ("Balsasud" brand) core material. The fin laminate is cut from 1.3mm carbon fiber sheet. The laminate is glossy on one side, while the other side has a matte textured finish designed to readily accept adhesives. The edges will be finished with strips of aluminum.
The balsa sheet will be cut to shape on a CNC, as you can see the CF sheet is already cut.
What I am currently pondering is how to laminate the skins to the core material. I am thinking about using melamine covered particle board and plywood to build a press of sorts. Using bolts around the edges and a few large c-clamps I would then compress the sandwich panel while it cures. We will be using Aeropoxy laminating resin to bond the CF to the balsa.
A couple of issues I can imagine running into:
How to keep everything lined up perfectly while it cures? It would be a major bummer if the layers were to slide around and get out of alignment. I am thinking about putting a couple of rods (or bolts) through the fin tab (so the holes will be hidden beneath the body-tube wall).
How to avoid getting resin on the glossy (finished) side of the CF sheet? I imagine a fair bit of resin is going to squish out from around the edges of the fins. We will be cleaning/squaring up the edges on a belt sander after it cures, but I am afraid that the resin could weep under the CF. Would covering the gloss side with a masking film of some sort (vinyl?) be smart? We could even use blue painter's tape, perhaps?
In the end we have decided to go with 1/2" end-grain balsa ("Balsasud" brand) core material. The fin laminate is cut from 1.3mm carbon fiber sheet. The laminate is glossy on one side, while the other side has a matte textured finish designed to readily accept adhesives. The edges will be finished with strips of aluminum.
The balsa sheet will be cut to shape on a CNC, as you can see the CF sheet is already cut.
What I am currently pondering is how to laminate the skins to the core material. I am thinking about using melamine covered particle board and plywood to build a press of sorts. Using bolts around the edges and a few large c-clamps I would then compress the sandwich panel while it cures. We will be using Aeropoxy laminating resin to bond the CF to the balsa.
A couple of issues I can imagine running into:
How to keep everything lined up perfectly while it cures? It would be a major bummer if the layers were to slide around and get out of alignment. I am thinking about putting a couple of rods (or bolts) through the fin tab (so the holes will be hidden beneath the body-tube wall).
How to avoid getting resin on the glossy (finished) side of the CF sheet? I imagine a fair bit of resin is going to squish out from around the edges of the fins. We will be cleaning/squaring up the edges on a belt sander after it cures, but I am afraid that the resin could weep under the CF. Would covering the gloss side with a masking film of some sort (vinyl?) be smart? We could even use blue painter's tape, perhaps?