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Marginal wind kites ?

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Pedro Marcos
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Re: Marginal wind kites ?

Postby Pedro Marcos » Sat Jul 28, 2018 9:03 am

kitexpert wrote:
Fri Jul 27, 2018 11:58 pm
tomtom wrote: 40 degree difference makes 200g per m3. I know 40 degree is little extreme but just little :) So in 3m3 kite it CAN be 600g uplifting force. I know this is very optimistic estimate but even half - 300g can make difference - especially in full line slack situation.


At 30 degrees air density is 1.16kg/m3, at 50 degrees it is 1.09kg/m3, about 70g/m3 difference. 9m AR 5 kite has volume of about 1.2m3, so in that case this effect would be 84g. Compared to kite weight and lift forces kite has when it is possible to kitesurf this kind of help is insignificant.

I was kite surfing on Thursday, no clouds and temperature peaked 26 degrees C. There was three foil kites on the water, Sonic2, Matrixx3 and Speed5. I helped Speed and Matrixx down but I didn't notice anything warm in them. With Sonic2 I had a nice low wind session, but I doubt it had any more hot air inside than those other two :)
It probably will have some influence on a 21m kite

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Re: Marginal wind kites ?

Postby jakemoore » Sat Jul 28, 2018 3:04 pm

foilholio wrote:
Sat Jul 28, 2018 4:27 am
Come on you can do better. Personally I am waiting for a Pullstrings reply and a kitexpert cad render.
I like the solar balloon kite concept a lot. But I also like PChem better than most sane people. Kite Experts argument is good. To make a significant difference that air inside the kite would have to get uncomfortably hot. I’ve observed lukewarm at best.

This has more maths for anybody interested: https://en.m.wikipedia.org/wiki/Solar_balloon

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Re: Marginal wind kites ?

Postby jakemoore » Sat Jul 28, 2018 3:16 pm

kitexpert wrote:
Fri Jul 27, 2018 11:58 pm
At 30 degrees air density is 1.16kg/m3, at 50 degrees it is 1.09kg/m3, about 70g/m3 difference. 9m AR 5 kite has volume of about 1.2m3, so in that case this effect would be 84g.
Hyperlink 9 in regular cloth is easily 2000 grams less than a similar sized wave or freestyle LEI. I wouldn’t spend a whole lot of time contemplating about the inertia of 1300 grams of air of trapped air in a 9m foil kites either. It’s there, but inserts less than Dacron and plastic bladder.

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Re: Marginal wind kites ?

Postby haare » Sun Aug 05, 2018 2:15 pm

I just bought Flysurfer sonic race 21m for marginal wind kiting. I have 15m already and will sell 18m.

I would say that the difference is very marginal compared to 18m. I would not buy it for summerkiting alone. Differece between 18m and 15m is definitely bigger.

I would say that with
21m I can kite in 2.5m/s.
18m I can kite in 2.75m/s
15m I can kite 3.5 m/s

However the difference in real life feels more. Our wind very commonly is between 2-4m/s. With 18 I can foil but I quite often will stall even from full speed in lulls. This often ruins the session because I cannot get to the middle of the lake where the wind is more steady. 21m I dropped from foil because of stall only once in 2 hour session in very marginal conditions. Also it is more meallow so it is easier to handle in gusty conditions.

It comes with a cost though. You need to be able to handle overpowered conditions well. Even 6m/s gust ask strength from your legs with 21m. With 18m I could handle 7m/s base wind. It is not only because of the extra sqm. It is also because it is so slow compared to 18m. So it stays in center of the wind window forever.

I must also add that I ride with zeeko spitfire which needs plenty of power. Moses onda and such probably don't benefit from 15+m kites.

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Re: Marginal wind kites ?

Postby TomW » Sun Aug 05, 2018 6:30 pm

I bought a used Sonic 2, 13m. Used it 5 hours, but only 2 of those in what I would call marginal. It was during a race, and other way more competent foilers were on 15-18-21 m foils. Diablo, FS Vmg, Soul.
I used 20m lines on a 50cm bar. It turns very very slow...
At this point I think it's a big investment for little benefits. I bet I will use this kite 10-12 hours a year, if that. I get it if you're racing....
I'm setting up a 60cm bar for it, see if we get dome marginal winds in August.

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Re: Marginal wind kites ?

Postby Pedro Marcos » Sun Aug 05, 2018 6:38 pm

TomW wrote:
Sun Aug 05, 2018 6:30 pm
I bought a used Sonic 2, 13m. Used it 5 hours, but only 2 of those in what I would call marginal. It was during a race, and other way more competent foilers were on 15-18-21 m foils. Diablo, FS Vmg, Soul.
I used 20m lines on a 50cm bar. It turns very very slow...
At this point I think it's a big investment for little benefits. I bet I will use this kite 10-12 hours a year, if that. I get it if you're racing....
I'm setting up a 60cm bar for it, see if we get dome marginal winds in August.
Use it with max 15m lines, it will handle much better.

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Re: Marginal wind kites ?

Postby TomW » Sun Aug 05, 2018 6:48 pm

Good idea Pedros. The bridles are like 3m in themselves...
I have the lines, I'll set it up.

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Pedro Marcos
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Re: Marginal wind kites ?

Postby Pedro Marcos » Sun Aug 05, 2018 6:57 pm

TomW wrote:
Sun Aug 05, 2018 6:48 pm
Good idea Pedros. The bridles are like 3m in themselves...
I have the lines, I'll set it up.
I also would not use it as a "marginal" wind kite, use it in 10+ knots.

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Re: Marginal wind kites ?

Postby Regis-de-giens » Mon Aug 06, 2018 9:07 am

Indeed. If we focus on extreme marginal wind , lines less than 20m is not part of the game (and Sonic 2 is to me not on the podium neither)

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Re: Marginal wind kites ?

Postby Pedro Marcos » Mon Aug 06, 2018 9:33 am

This weekend i realised rider ability its way more important than the kite, so we really need "the same rider" to test all kites in the same conditions. Im now very used to my R1V2 19m in 15m lines and i was feeling very confortable in 5-6 knots, so i made the mistake of "saying yes" to a friend that wanted to try... instant swim, didnt even stand up, he tried to get up by pumping the kite, kite went to the edge of the window, stalled and swim.... So being used to the kite in this conditions is quite important.


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