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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Wed Dec 02, 2009 12:33 am 
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le zee wrote:
Hi all,

I'm Nicolas Caillou (we know together Peter!!!) and one of the guy riding the foil strapless.

I finished 2nd of 2 racing contest in France (overal of the year 4th), and the French racing Champion is a foil riding: Mac Blanc, we fighted hardly on the contests all the year long, but he is really good.

Foil riding is awesome in light wind, specially because you don't have to force to use the board and the feeling is the same as a "flying carpet".
You cannot describe the feeling if you don't know it.

here a small video about the contest in france
http://www.vimeo.com/6980941


Hi Nicolas, good to hear from you and see you racing. I simply MUST try a "magic carpet" one day - looks sooo smooth, and I like the strapless thought ! Just not easy to find around here.

; -) Peter


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Wed Dec 02, 2009 3:03 am 
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Location: NW Pacific
Hydrofoils, tough nut. The Carafino type wing is more like an old fashioned diamond shaped kite in that it doesn't have the high pressure, low pressure aspects of a true wing, Like LEIs and foils and airplane wings, etc. It doesn't get sniffy when it's going 8 knots through the water or 20. It just depends on its angle in the water to provide lift.

The dual job first mentioned in this thread does have a true wing shape. Or at least that's what I am led to believe. I built a dual "true" bi-directional hydrofoil board 4 years ago. It popped up in 8 or so knots and after that gained speed really fast once the friction of the board was eliminated. It also started severely cavitating and porpoising. It went upwind like a train on tracks and actually caused my hips a lot of aggravation attempting to steer it. It was a piece of cake to use and I got up first try. With a not very advanced kite compared to now, FS Titan 18.

True water hydrofoils have a very finite ability to function in a range of speeds unless they somehow decrease in size with speed or are adjusted in angle of attack. Some of the big hydrofoil sailboats have a dedicated computer adjusting the angles. Some have a forward or rear ski that senses the water surface and makes the adjustments.

Many complications for a small contraption. I saw the British board a year ago and it wasn't available then nor is it now. Wonder why. Armin of FS is keen on this and tried my board but found it to have too much wing shape, i.e., rose too quickly and therefor no good at higher speeds.

Love to see somebody get it figured out but fearful the dual approach may never "fly".

All in all, having owned a few different types of hydrofoils, after you get over the first few thrills of flying above the surface of the water, I find them ultimately boring compared to a regular board. Kinda like wearin a rubber. Sorry.


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Wed Dec 02, 2009 8:05 am 
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Location: Slovenia
Hi Chemosavi,
Do you have some photos of the board you have build? I would like to bould one someday, so I would like to gather as many information as possible.
Thank you!
Jaros


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Wed Dec 02, 2009 10:22 am 
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The strapless riding is due to the fact we are trying a lot of different wings, then the location of feet change as a function of the wing. This is why I ride strapless. For contests when I'll validate a wing, maybe I'll restrap (for more control)
Additionnaly, strapless is more safe at high speed (this is not real high speed, but with a foil board is not too bad).

The carafino board is perfect to learn the foilriding but the performance is not high.
Actually on the French tour (don't have time to do other ones) 4-5 people use foils. 100% of the riders have customized wings.

With the carafino wings, I'm able to ride at a max of 18knots speed.
With my current wings, I can ride at 24-25knots speed gaining in upwind ability too.
We are at the starting of the development, wait and see next season!
But love the feeling, love to ride strapless, but I miss jumps with a foil, which is super funny (specially front and back loops)


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Wed Dec 02, 2009 10:55 am 
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Location: NW Pacific
........

here' tiz


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Wed Dec 02, 2009 11:14 am 
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Location: Slovenia
Hi chemosavi,
Thank you for a quick reply but for some unknown reason I can not see the photo. Where should be a photo I only see a window with a red "x" sign. Someone knows why?
Greetings,
Jaros


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Thu Dec 03, 2009 12:32 am 
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Hi Chemo,
Very cool looking circa 2005 foil. But looking at the cross section shape, I would think that a tunnel foil would help solve both issues with your foil:
1) less lift
2) better water flow at high speeds.
Roy Stewart makes surfboards with the tunnel fin, would be cool to see it adapted to a hydrofoil.
http://en.wikipedia.org/wiki/Tunnel_fins

What's a good NACA foil for a hydrofoil?


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Thu Dec 03, 2009 4:07 am 
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le zee wrote:
The strapless riding is due to the fact we are trying a lot of different wings, then the location of feet change as a function of the wing. This is why I ride strapless. For contests when I'll validate a wing, maybe I'll restrap (for more control)
Additionnaly, strapless is more safe at high speed (this is not real high speed, but with a foil board is not too bad).

The carafino board is perfect to learn the foilriding but the performance is not high.
Actually on the French tour (don't have time to do other ones) 4-5 people use foils. 100% of the riders have customized wings.

With the carafino wings, I'm able to ride at a max of 18knots speed.
With my current wings, I can ride at 24-25knots speed gaining in upwind ability too.
We are at the starting of the development, wait and see next season!
But love the feeling, love to ride strapless, but I miss jumps with a foil, which is super funny (specially front and back loops)


re: carafino foil. Without being an expert this seems to be my impression too. It was way easier to ride than the Neil Pryde one.


If you want to divulge info that would be great....tho I am assuming no.

I can agree with the riding out of straps. When you fall with a foild board, it hurts a lot more than the same fall with a regular board.


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Thu Dec 03, 2009 9:19 am 
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sflinux wrote:
What's a good NACA foil for a hydrofoil?

Mahalo HydroLovers :heartface:

Good qestion @sflinux, I can ask my self the same. You know there is no answer ;-)
Any NACA can be good, question is for what and for which speed/lift range
you are looking to be used. The safe one is for sure 0009 used on most Moth Foils, but
here it is http://en.wikipedia.org/wiki/NACA_airfoil something to study on :thumb:

Following this discussion over, one point to see here ;-) The same guys pushing
the hydrofoils forward! Good! The kite surf foils are stocked somehow at the moment,
no right development or better results as we have the state of the art on the products.
I was move a bit out from kite scene and I was even not riding my "Blade" this summer,
at this moment Moth boat and the development of the foils there makes me busy!

My Blade kite-hydrofoil 2007
Image

More of the moth foils can be find here
http://drlojz.blogspot.com/2009/11/i-am-connected-to-nature-air-and-water.html
Image

as I say the kite hydrofoil is somehow stocked, the Moth foils have problem with the ventilating and
cavitation. The Kite-foil will or have the same problem. weary good video of this "phenomena"

http://www.youtube.com/watch?v=qDpnXsAB1oc

More about this on
http://forums.sailinganarchy.com/index.php?showtopic=98777
and
http://www.boatdesign.net/forums/sailboats/moth-foils-30-31-knots-34-86-mph-11209-63.html

Be good, be creative and have fun, but don't even to try to go against nature ;-)

dr.Lojz


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 Post subject: Re: Twin Tip Hydrofoil
PostPosted: Thu Dec 03, 2009 10:24 pm 
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Joined: Sat Oct 30, 2004 11:35 pm
Posts: 170
Location: Rome Italy
I love my FOILBOARD
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