Foiler Design

[bistros]

Originally Posted by Doug Lord

Hey Pi-that picture is in "Icarus the boat that Flies". The boat was owned by Frenchman Claude Tisserande and he claimed an unofficial speed record of 20 knots. He is credited with improving the top speed ever achieved by a 470(up to 1975) by 5 knots. He used two surface piercing foils forward and a t-foil aft. There was also an FD that flew with the same configuration in about the same time frame ,if I remember correctly.
But the first monofoiler in history is probably Monitor ,a US Navy project with Baker Mfg. from 1950-56 in the USA. She was timed at 30.4 knots- a speed not yet equalled by the Moth(but it will be soon).

Bill Hansen of Hansen Aerosports - he built a fully foiling FD in the 70's in SF.

And this one in Europe: http://www.wind-water.nl/hydrofoil.htm Click on "FD H40"

[sigurd]

hey Paul Scott, Ive stopped reading this thread but am looking at all the nice pictures. (I now started reading again! )
If you could illustrate your bruce foil idea, or explain a bit more in detail how you would place them.

[Paul Scott]

Hey Sigurd. Frankly, the more I think about it, the only way to do it is to make some educated guesses, strap 'em on, and see what happens. But my right shoulder is too fragile (too many years of having too much fun, and the surgery that came along with that) for that, so it's the educated guesses part at this point. If you treated a largish bruce foil (3' chord on top?) like a sinker, except your feet would be strapped to the top of the thing, so that it had just enough flotation to keep your feet just at the surface of the water when it was vertical, you might be able to at least waterstart it- it would be like standing on the top edge of 2 kickboards tied together, though, which I know is doable without straps (way too many years spent swimming 18,000 metres a day), and then somehow steer it with your legs and ankles, at least you would be at the same angle as a normal kitesufer is relative to the control lines as the the bruce foil inclined away from the kite, but since bruce foils tend to bury away from the sail force, how on earth would you control it? Has anyone out there ridden (standing) on the top of a bruce foil? It would be like railriding a really small windsurfer that wanted to move down and to leeward the faster it went. I don't know if or how the foil would find equilibrium without control input. It might. Wish I was 22 again. If you limited the amount of travel, you could articulate the foil into 3 parts, and control the amount of camber without breaking your ankles, maybe. And steer it that way, maybe control the amount of lift/drag. hmmmmmm....

What do you think? If it worked, a kite might actually sail to windward!

I suppose you could strap on two foils like iceskates, but must go keep culture safe for Seattle.

Paul

[Tcubed]

Kites do sail to windward already.

For a bruce foil to be worthwhile the pull of the kite should exceed the weight of the kiteman, which would make starting an extra challenge. I'm sure there are ssolutions though.

[Paul Scott]

Mr. T; define 'sailing to windward'?

Paul

[sigurd]

Sailing to windward is sailing any course closer than 90` to the wind. Closer to the wind is called better or higher pointing. The lift / drag of the vessel decides pointing ability. I haven't seen polars of kiteboards or windsurfers but both can sail pretty close to the wind.

[Chris Ostlind]

Paul,

If you are into sailing and you live in Seattle, surely you know of the remarkable winds the run up the Columbia River Gorge, which separates Washington from Oregon?

Here's a friendly Google list of the potential there. It's sailing spot for kitesurfing, windsurfers and trad sailors that you should not miss in your lifetime.

http://www.google.com/search?hl=en&q...iling&aq=f&oq=

Even a cursory exam will put you hot on the trail of amazing wind powered sports, terrific lodging potentials and a cadre of enthusiasts who will regale you with tales of fabulous potential.

You owe it to yourself.

[sigurd]

I wonder if ventilation and cavitation can be prevented by injecting water to the lowest pressure area near the leading edge? A slit in this area could possibly be connected to a slit nearer the trailing edge, to suck away the separation bubble? Possibly it would be working like a foil with thicker leading edge?

[Tord]

Originally Posted by sigurd

I wonder if ventilation and cavitation can be prevented by injecting water to the lowest pressure area near the leading edge? A slit in this area could possibly be connected to a slit nearer the trailing edge, to suck away the separation bubble? Possibly it would be working like a foil with thicker leading edge?

Interesting idea! But I'd think a fan/pump would work better ...

Tord

[Paul Scott]

Originally Posted by Tcubed

Kites do sail to windward already.

For a bruce foil to be worthwhile the pull of the kite should exceed the weight of the kiteman, which would make starting an extra challenge. I'm sure there are ssolutions though.

In my experience, the kite had to pull me from the water to waterstart. I suppose you could take off from the beach....

Paul

[sigurd]

Like this
here fellow?
I found an interesting way to construct a fair flap hinge.

Thanks, Sigurd! One of my concerns has always been what happens if the foil flexes. I've tested "solid state " hinges like on early Ilett boats that would bind if flexed . Anybody have experience with this hinge method?

[sigurd]

I don't know solid state hinges. is it the ones with only a membrane hinge, or perhaps the piano hinge sort?

you could look at the "variable camber" thread of mine also, such a foil would have the core removed in the aft part and a slit between upper and lower trailing edges, some sort of mechanism like ropes, hydraulics or conrod/twist rod would then flex the unsupported aft skins.
I'd rather like to find out whether a jet flap can be used where the input pressure would be simply taken along the stagnation line of the strut; no moving parts, no draggy flap when slow moving. I suppose that the stagnation pressure may not be high enough. I remember reading about some boat using this actuation method at least, can't remember whether it used normal flap, inclination, jet flap or some other lift augmentation. I'd be glad if anybody knows the boat i'm talking about.

Originally Posted by sigurd

I don't know solid state hinges. is it the ones with only a membrane hinge, or perhaps the piano hinge sort?

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John Ilett used kevlar fabric with flexible epoxy resin. I have used mylar sheet
which worked well on model foils. I also experimented with foils having short overhanging flap so that foil flexing wouldn't be a problem: