Foil building

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BenIOW
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Foil building

Post by BenIOW »

I'm looking to build a new rudder blade for my firefly, does anyone have any tips or links to good guides?

I assume that ply won't be strong enough so will need to laminate up some planks, any suggestions on good woods to choose?

Any help much appreciated! :D
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JimC
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Re: Foil building

Post by JimC »

The Cherub guide is good for high end foils, http://www.uk-cherub.org/doku.php/tech/foils, however if I read the rules right it looks as if you're not allowed to glass or carbon sheath foils. Ply foils work on lots of lower powered classes, but I suspect they're probably only reliable when you're not allowed to shape the blade, and again I think the rules may prohibit ply. You'd want to build the rudder blank in strips in the way the article describes, but I don't know if all cedar would be good enough or whether it should be part or all hardwood - sapele or something.
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PeterV
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Re: Foil building

Post by PeterV »

I built a Finn rudder blade out of Western Red Cedar strips about 8 or 9 years ago, it's still in as new condition. It was shaped then coated with glass and epoxy.
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Rupert
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Re: Foil building

Post by Rupert »

As you can't glass it, you do need some tougher wood on leading and trailing edge, and maybe also down the middle. Edge gluing is the way to go, as ply has half the grain running the wrong way, so can break.
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Ed
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Re: Foil building

Post by Ed »

Gosh......maybe my rudder is out of class.....

I knew you couldn't cover foil in glass, but I have put a inset a fibreglass trailing edge into the wood for the last 5mm or so and then filler on that to give the rudder a feather edge. Is that not Kosha?

But, yeah, the way to do it is to laminate some strips of wood and alternate the grain, then cut down to size/shape.

Various ways of doing that. By eye with belt-sander electric plane works, working down to a femail template.

Setting up a router and ripping it down to established depths and then finishing with belt sander, worked very well for me when I cut my IC foils from foam, but it took lots of thinking and preparation time. I would do it again for making up another set of foam/carbon foils, but to be honest for a Firefly rudder, would most probably do it by eye and offering up to template.

eib
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Rupert
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Re: Foil building

Post by Rupert »

You can do an epoxy trailing edge, but no glass allowed. Unless made by Rondar, of course...
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Ed
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Re: Foil building

Post by Ed »

mmmm....can't see it being an issue, but it still sounds like I am potentially out of class....

I think I used a thin core of glass at the centre and then put filler around that to build up the feather. But it isn't a 'coating' it is at the core.

Hell, it doesn't really matter too much, I can't see anyone complaining in local club events.

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Bathurst Whiff - looking for someone to love it
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