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DIY Foil Kites

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stefmoris
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Re: DIY Foil Kites

Postby stefmoris » Fri Dec 30, 2016 10:25 pm

Foilholio Chikara is 42gsm. I do not have a fixed limit to my B lines so Mixer depowers onto A. -stef

kitexpert
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Re: DIY Foil Kites

Postby kitexpert » Fri Dec 30, 2016 11:09 pm

stefmoris wrote:Foilholio Chikara is 42gsm. I do not have a fixed limit to my B lines so Mixer depowers onto A. -stef
I don't see the weight an issue at all , your kite is a light weight kite.

To depower onto A is quite tough test for stability. I don't see it very possible because of the high AR and the shape of the airfoil. If it doesn't work some limit to B should be considered, I guess there is not much else to do...

Btw, what is the location of A row by the chord, % ?

foilholio
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Re: DIY Foil Kites

Postby foilholio » Sat Dec 31, 2016 2:12 am

I think it is a bit of a gamble onto A alone, but you obviously have more experience now with a few kites so the risk is lower.

I too would like to know your chord positions A and B would be good. Did you vary the cord positions over the span? I remember measuring a pyscho4 a long time ago and there is quite some variation, but that is a different kite.

stefmoris
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Re: DIY Foil Kites

Postby stefmoris » Sat Jan 07, 2017 11:15 pm

"A"s are at 10% and "B"s and "C"s vary their position through the span. -stef

stefmoris
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Re: DIY Foil Kites

Postby stefmoris » Fri Jan 13, 2017 2:18 pm

phpBB [video]

socommk23
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Re: DIY Foil Kites

Postby socommk23 » Fri Jan 13, 2017 2:27 pm

Brilliant!

Phezulu1
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Re: DIY Foil Kites

Postby Phezulu1 » Fri Jan 13, 2017 11:54 pm

Hi Stef
Looks like you've done it again, fantastic!

I can't wait to see some more footage, looking like a winner so far :D

kitexpert
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Re: DIY Foil Kites

Postby kitexpert » Sat Jan 14, 2017 12:20 am

Thank you Stef for all of your work and its fine presentation here :thumb:

Kite looks good and remembering high AR and quite low cell count it is even more remarkable. Your choices for other parameters have been successful, I'm not at all sure I had done it as well from design basis you started with.

I see the wind was very low there (like it should be for the first tests), but kite is fully inflated and flys well as far as I can see. Canopy curve is perhaps a bit mild to my eye, but it is more or less a matter of taste and a compromise between different things.

I see some problem with the brakes, some distortion at the TE. Because of wide cells you could have bridled it on every rib. There is not much difference if brakes are on 95% or at the TE, so you can add lines there if it is necessary. Brake bridle is not the most important thing in a foil kite but to have it to turn TE smooth, almost hard to see way, gives the best drag/effect ratio.

Your work has been inspiring, in fact it inspired me doing some real kite work again. And as we both know making a foil kite from the scratch, from the beginning, gives you a lot of understanding and thorough knowledge how it is made down to smallest detail. You must design and think every parameter and you should have some kind of justification for each choice you make. You must make a lot of decisions - that is what design is. It is funny to hear someone say "Ah, you designed it with a computer", like computer or design program was the reason for possible success...

:thumb:

foilholio
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Re: DIY Foil Kites

Postby foilholio » Sat Jan 14, 2017 2:39 am

Looks well designed and made. Some of my Pansh's have TEs pull like that. I wonder if it has efficiency advantages as fluid dynamics is not always straight forward. Might confuse our resident expert :lol:. Straight lines and uniform shapes are the thinking of a simplistic design mind. You just have to look at the shapes of differing airfoils and their performance to see the designs that work well are far more involved.

stefmoris
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Re: DIY Foil Kites

Postby stefmoris » Sat Jan 14, 2017 5:14 pm

Thanks everyone for the nice comments!

I'm really happy with how solid it feels relative to my last kite for only having 25 cells. As you can see there is a lot less jellyfishing and wrinkles than my previous one. The precision of the laser cutting (before when I pen plotted I had material slippage), the crossbracing, and correct billow (thus strap tension) all add up.

I've already ordered the material to sew up an 8 and a 15! It will take me all summer to really learn all I can from this design so I'm just going to scale it up and down.

My personal goal is to do at least two races this summer on my own kites, and not finish last!! I feel like I could win the whole hydrofoil pro tour when I'm designing and sewing them up, so I think its all doable!!! And my blinding flourescent colors are part of the strategy!!! :)

It is too cold for my tastes here in Italy right now so I'm sending off my kite to someone far more capable then myself (I'm intermediate on the hydrofoil and still trying to figure out the air gybes!) to put it through its paces. I will share on the water feedback, gps tracks, video etc.... when I have it - probably March-ish.

I also had some second thoughts about my brakes after reviewing the video, and after going over my spreadsheets and 3D model I found I had forgot to scale up my brake pigtails - so in the video my brake lines are 10cm too short!! This doesn't make the trailing edge smoother per se but should lesson the amount of deformation. When I'm charging around on a reach or upwind my D's are loose anyway as all my kites fly on the ABCs with D's engaging for downwind or max turns, or flying overhead coming back to the beach to prevent overflight etc....

Kitexpert I hope you develop that 80 cell monster of a kite I saw you posted in another thread! Then we can have a virtual battle of the gps tracks!

:) -stef


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