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Carbon mast layup

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wdric
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Re: Carbon mast layup

Postby wdric » Sun Mar 02, 2014 11:52 am


teknologika
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Re: Carbon mast layup

Postby teknologika » Tue Mar 04, 2014 12:03 am

Hi Scuba,

I haven't built any kite hydrofoils (yet) but I have successfully built a number of moth hydrofoils over the years so I can offer some advice.

Firstly ... you definitely can build a foil in a single session, my first T foils were a 4 hour wet lamination process from start to finish, done in 4 1hour stages (left skin, right skin, bottom skin, then bog join).

I would stay away from a balsa core, I used one in my first moth foil, and it added nothing, the foil broke and sank quickly to the bottom of Lake Macquarie.

I have written up a how to guide for moth foils on my blog which you might find useful ...http://www.teknologika.com/mothblog/wp-content/uploads/2009/10/Home-Building-a-Carbon-Moth-Part-2-Foils.pdf

As I mention in the document, you probably want a couple of layers of +/- 45 and 6 ish layers of uni. Just go 100% carbon, as everything else just adds weight at the expense of strength.

Bruce

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Re: Carbon mast layup

Postby tkettlepoint » Tue Mar 04, 2014 12:18 am

Bruce good to have you here. I have read your blog awhile back and your info is great. learn a lot of you.. thank you

terrie



teknologika wrote:Hi Scuba,

I haven't built any kite hydrofoils (yet) but I have successfully built a number of moth hydrofoils over the years so I can offer some advice.

Firstly ... you definitely can build a foil in a single session, my first T foils were a 4 hour wet lamination process from start to finish, done in 4 1hour stages (left skin, right skin, bottom skin, then bog join).

I would stay away from a balsa core, I used one in my first moth foil, and it added nothing, the foil broke and sank quickly to the bottom of Lake Macquarie.

I have written up a how to guide for moth foils on my blog which you might find useful ...http://www.teknologika.com/mothblog/wp-content/uploads/2009/10/Home-Building-a-Carbon-Moth-Part-2-Foils.pdf

As I mention in the document, you probably want a couple of layers of +/- 45 and 6 ish layers of uni. Just go 100% carbon, as everything else just adds weight at the expense of strength.

Bruce

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Re: Carbon mast layup

Postby teknologika » Tue Mar 04, 2014 1:28 am

tkettlepoint wrote:Bruce good to have you here. I have read your blog awhile back and your info is great. learn a lot of you.. thank you

terrie



Glad I could help.

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Re: Carbon mast layup

Postby ozchrisb » Tue Mar 04, 2014 2:35 am

Thanks Bruce. I've been reading your blog too. Great to have you here! Any thoughts on doing a surface following kite foil? Would you even be able to counteract someones weight pushing in the wrong direction.

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Re: Carbon mast layup

Postby ronnie » Tue Mar 04, 2014 9:59 am

ozchrisb wrote:Thanks Bruce. I've been reading your blog too. Great to have you here! Any thoughts on doing a surface following kite foil? Would you even be able to counteract someones weight pushing in the wrong direction.


This is a foil designed to self-regulate its depth. My guess is that it works off the water pressure at different depths.



Here is a write-up on the project (in French).

http://www.augredelair.fr/joomla/recits ... ledeau.pdf

If you jump to Page 121, I think that illustrates that he had a bladder in a tube that was compressed by the water pressure and the shorter bladder operated a flap at the back of the rear of the hydrofoil.
The equivalent would probably be a bladder inside the fuselage that when compressed by greater water depth, would operate a rod to pull a rear flap (like what happens with the flap on a Moth) to counteract whatever the change in water pressure (depth) was.

This design though, was for something which was trying to maintain a constant state. That may not be so suitable when you are gybing or tacking or jumping.

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Re: Carbon mast layup

Postby teknologika » Wed Mar 05, 2014 2:01 pm

ozchrisb wrote:Thanks Bruce. I've been reading your blog too. Great to have you here! Any thoughts on doing a surface following kite foil? Would you even be able to counteract someones weight pushing in the wrong direction.


Would it be able to counteract? Maybe. It would all depend where the wand paddle was tracking the surface of the water. If it was right at the front, then if you leaned forwards (lowering the AOA) then, yes the wand would induce more lift as you would be lowering the hinge point and compressing in to the waters surface. That would be great at low speed to make the foil less prone to incorrect angle of attack when riding, however that would be really bad at high speed when you were leaning slightly forwards (deliberately) as the speed and the lift of the foil increases.

Too far back and it would amplify what you are doing instead of reducing it.

So .. maybe it could work, but it would need a lot of R&D, testing and tuning.

On our boats we have fine on the water adjustment for just about everything (I have 5 control lines on the wand alone (length, gearing, neutral setting, spring rate and a stop line), and we change it around the course. I am not sure how you could include that sort of adjustment in a kite foil.

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Re: Carbon mast layup

Postby Bille » Wed Mar 05, 2014 6:18 pm

The Hobie tri-foiler used a surface devise on their foil ; it looks
to work Ok. At .22 seconds, you can see how it works :

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

Bille

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Re: Carbon mast layup

Postby plummet » Wed Mar 05, 2014 8:29 pm

I have laid up parts greater than 7mm thickness. Yes it is possible.

The issue you will have is the first layers starting to go off before you vac bag it. That means you can have a resin rich layup. Not ideal.

Why 30 layers at 7mm? that does not make sense. Use heavier weight carbon in uni and double bias.

You could get your layers down to 10. Use 600gram insteat of 200grm weights. If you want a nice looking layer then put the 200gram twill on the outside only.

Will 10 heavier layers you physically will be able lay up the job faster and get the vac bag sucking before the resin goes off.

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Re: Carbon mast layup

Postby teknologika » Fri Mar 07, 2014 6:49 am

Bille wrote:The Hobie tri-foiler used a surface devise on their foil ; it looks
to work Ok. At .22 seconds, you can see how it works :

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

Bille


The hobie tri-foiler canard based control system won't work as you don't have the separation between rudder and front hydrofoils that the hobie has.


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