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Gel coat and a foil wing

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downunder
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Gel coat and a foil wing

Postby downunder » Thu May 26, 2016 1:45 pm

Hey guys

exiting times ahead!

I am making a foil wing and decided to join two big fins off my race board to form a shape.

And already ruing it :(

What happend is, the gel coat is clearly reacting with the fin surface under the heaps of wax. Heaps, like 8 layers of max release wax by Meguiars.

This can be seen as wrinkled area in red. I am now worried and thinking not to pour the rest on top of it to create a mold.

I did make one mold already off epoxy, which worked just fine on the waxed surface. But the gel coat?
DSC_0013.resized.JPG
What do you think?



Thx

D.

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Re: Gel coat and a foil wing

Postby TheJoe » Thu May 26, 2016 3:15 pm

Why gel coat? Really how much uv protection is a foil going to need? It is in the water most of the time and your not going to store it where the sun is constantly on it. Plus the texture of the cloth should help help with the drag like a golf ball.

I that's my laziness talking.

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Re: Gel coat and a foil wing

Postby downunder » Fri May 27, 2016 1:41 am

Hi Joe,

thanks for your reply.

I am making a mold FOR the wing...Gelcoat is used coz epoxy doesn't stick to it when making a product. Anyways, I dodged to bullet and poured all on top of this. If you look carefully, two MDF boards are bolted together and they form the outline of the mold.

The gelcoat is needed on top of the fin Im replicating. The epoxy is poured on top of gelcoat when tacky. Some light fiberglass as well to make the mold stronger.

When cured, I'll unbolt the MDF boards, and take the fins out carefully. The result should be a mirror shine mold. Than I can make a wing super fast and replicated many times if I wish.

Or, I can make the fins as well. So two birds with one rock. In theory :)

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Re: Gel coat and a foil wing

Postby plummet » Fri May 27, 2016 2:14 am

Side issue. Doesn't look like you have any anhedral in the wing design..... Looks too flat. All my research points to the fact that you need anhedral on the winds for stability.

Ps I haven't built one yet some my advice is only theoretical.

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Re: Gel coat and a foil wing

Postby TheJoe » Fri May 27, 2016 2:22 am

Ahh I see. I have only used silicon for making a molds in the past. Silicon is the way to go but very expensive.

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Re: Gel coat and a foil wing

Postby downunder » Fri May 27, 2016 3:08 am

Hi Plummet,

the pic doesn't reveal much :) But it's all there. It might be an awesome build. The target is a very light foil (you know me, I'm not a heavy dude).

Joe, indeed, silicone is a go for a beefy build. Myself going with as cheap option as I can. The mold is semi cured now, can't wait to take it off.

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Re: Gel coat and a foil wing

Postby Starsky » Fri May 27, 2016 3:23 am

plummet wrote:Side issue. Doesn't look like you have any anhedral in the wing design..... Looks too flat. All my research points to the fact that you need anhedral on the winds for stability.

Ps I haven't built one yet some my advice is only theoretical.
Research?

Zeeko alloy is flat. Very stable, quite fast, easy to learn on with plenty of performance. Well liked and reviewed.

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Re: Gel coat and a foil wing

Postby downunder » Fri May 27, 2016 3:38 am

^
Agreed, a lot of it is a marketing thingy...Flat wings work just fine with a vertical mast acting as a roll stability. 30 kn easily achievable (not interested in that anyway ;)

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Re: Gel coat and a foil wing

Postby plummet » Fri May 27, 2016 7:07 pm

Starsky wrote:
plummet wrote:Side issue. Doesn't look like you have any anhedral in the wing design..... Looks too flat. All my research points to the fact that you need anhedral on the winds for stability.

Ps I haven't built one yet some my advice is only theoretical.
Research?

Zeeko alloy is flat. Very stable, quite fast, easy to learn on with plenty of performance. Well liked and reviewed.

I'll be honest. I cant be fucked digging up the threads, But has been discussed at length by foil builders would have build more foils than you or I. It also makes sound aerodynamic sense to have anhedral/dihedral. Go and look at almost any aircraft and you will find dihedral on the wings. Look at any bird or any fish....

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Re: Gel coat and a foil wing

Postby Starsky » Fri May 27, 2016 10:40 pm

I will likely never build a foil.

Totally depends on the plane or the foil, or fish I guess!

Nicholas from Zeeko has said he prefers flat wings for waves for better agility with respect to yaw.

Sail planes have dihedral some supersonic jets have anhedral. Aerobatic and Red Bull racing planes are flat wing. It's certainly a component of most race foils, but some of the most impressive freeride foilers use flat wings. I kinda like that on my foil yaw control is largely a function of the vertical fin on the tail. Its a standard TT fin, and can be sized to your preference.

I don't doubt theres a lot to designing a great wing for foiling, but anhedral is not essential. I see its a key part of many good designs, but you can obviously make a fantastic foil with nice broad performance envelope using flat wings. They exist.


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