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Re: Hydrofoil Wing Build

Posted: Fri Aug 07, 2020 8:58 am
by RichR2
Cathedral !!!! Dont you just hate predictive text... Anhedral

Re: Hydrofoil Wing Build

Posted: Fri Aug 07, 2020 11:41 am
by Kevin Brooker
Cutting a strip of woven material about 3 cm wide on the bias will allow it to wrap the LE. The top and bottom can be overlapped with a small gap which leaves a continued layer. Another bias ply can be laid on top of the joint so there is more material to grind away to maintain the LE profiles. A light dusting of spray adhesive (3M77) prior to cutting will hold the strip together and allow you to attach it prior to wetting it out. The adhesive won’t hinge the wet out or bonding. If you are vac bagging the same thing works for the peel ply to avoid wrinkles.

Re: Hydrofoil Wing Build

Posted: Sat Aug 22, 2020 8:45 am
by OzBungy
I just laminated a strip of carbon around the tip of my foil from about 100 mm onto the leading edge, around the tip and about 50 mm onto the trailing edge. The strip was about 300 mm long and 100 mm wide (overlapping the top and bottom by 40-50 mm).

It went very well from the leading edge and around the tip. It didn't quite go around the sharp corner onto the trailing edge.

I could have done a relief cut or two, but just cut the end bit flush. I've since added a small patch that closes a tiny gap and wraps the sharp corner.

I think there's a relationship between the collection of angles you're trying to wrap and the size of the patch you're laminating. It's fairly obvious once you start and try and do it. There's a whole world of people doing cosmetic carbon skinning around all sorts of complex shapes. There's loads of videos showing the basic techniques, and some pretty odd looking attempts.

I did spray the carbon with a little 3M Super 77 adhesive. That stopped the carbon shredding and allowed me to practice positioning and flexing the carbon to fit. Even with the adhesive dry it sticks a bit to the carbon surface of the foil. It's fairly easy to peel off.

According to all the youtube videos I could have left it stuck on then applied the epoxy over the top. I wanted to wet out the carbon from underneath to avoid the risk of a dry lamination. It wet out and stuck down pretty well with a plastic squeegee.

I made a sleeve of peel ply sewn to the exact shape of the tip of the foil. Once that was pulled into position the carbon was very neatly locked into place. I ended up with a couple of tiny wrinkles and the small gap on the tip that I filled with a second patch.

I think it would be quite easy to laminate a strip for the whole leading edge that would wrap the top and bottom.