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High Pressure kite by Bruno Legaignoux

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brunolgx
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Re: High Pressure kite by Bruno Legaignoux

Postby brunolgx » Sun Dec 16, 2018 3:50 pm

BWD wrote:
Sun Dec 16, 2018 6:18 am
now in the public domain and un-patentable.
No worries, it’s been done before anyway
I don't mind if it has been done before or not (if it has, why there is not such a kite on the market ?) but when you make such statement it would be interesting for everybody that you give your sources. Thanks in advance.

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Re: High Pressure kite by Bruno Legaignoux

Postby kitexpert » Sun Dec 16, 2018 3:58 pm

OK, thanks spritrig for your calculations. Personally I'm not so fond of any high pressure possible exploding things near me even if they wouldn't be risk for health.
spritrig wrote: It isn't a stiff leading and trailing edge that is needed, with a foil kite type bridal system. Something to hold open the kite to get tension on the bridles quickly which give shape to the kite is what is needed.
That is only partially true. More stiffness better handling, both in the air and on the ground/water. If LE isn't rigid enough it will bend and fold for example when parked at the edge of the WW.

I'm afraid "circuit battens" are too weak - if not they will be too heavy and cumbersome.

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Re: High Pressure kite by Bruno Legaignoux

Postby edt » Sun Dec 16, 2018 4:46 pm

Fantastic work Bruno. Can't wait until we get one of these kites on the market. I remember both the Hellfish by Best back in 2004 and the Ruben Lenten Extract in 2014 both were market failures, those both used cuben fiber (dyneema fabric), and while the Hellfish died due to quality issues and the Extract failed mainly because it was a C kite and thus had no market, so I remain convinced that high pressure kites are the future of inflatable kites. There's just too much drag you can remove from the kite when you use higher pressure kites. right now we are not even using 1 bar pressure. There's vast room for improvement.

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Re: High Pressure kite by Bruno Legaignoux

Postby tilmann » Sun Dec 16, 2018 6:17 pm

kitexpert wrote:
Sun Dec 16, 2018 3:58 pm
OK, thanks spritrig for your calculations. Personally I'm not so fond of any high pressure possible exploding things near me even if they wouldn't be risk for health.
I pump my bike with 60 PSI. No explosions so far 8)

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Re: High Pressure kite by Bruno Legaignoux

Postby kitexpert » Sun Dec 16, 2018 6:58 pm

tilmann wrote:
Sun Dec 16, 2018 6:17 pm
kitexpert wrote:
Sun Dec 16, 2018 3:58 pm
OK, thanks spritrig for your calculations. Personally I'm not so fond of any high pressure possible exploding things near me even if they wouldn't be risk for health.
I pump my bike with 60 PSI. No explosions so far 8)
I have even more in my road bike 23mm tires. This "problem" or fear should not be exaggerated :)

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Re: High Pressure kite by Bruno Legaignoux

Postby spritrig » Sun Dec 16, 2018 9:40 pm

Ah yes. There are single line kites like that! Focus on kiteboarding has gotten me out of flying single line kites which have a lot more diversity of designs. I forgot from my single line days. https://prismkites.com/product/eo-atom/

Kitexpert, how stiff are foil kites? Do they fold at the edge of the wind window? The pressure in foil kites are really low and the shape is formed by tension on the lines. Tires are well developed. I am sure that high pressure kites can be reliable and safe like tires. My concern is that Bruno has no injuries. So he can develop without delay. So we can enjoy his this next contribution to the sport!

(The hand surgeon that stitched my hand back together told me, with a wry smile, "you know nothing about refrigeration". Actually I did, but I did something very stupid. So I have professionals work on my AC then on.)

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Re: High Pressure kite by Bruno Legaignoux

Postby FarQueLot » Mon Dec 17, 2018 3:04 am

spritrig wrote:
Sun Dec 16, 2018 9:40 pm
Ah yes. There are single line kites like that! Focus on kiteboarding has gotten me out of flying single line kites which have a lot more diversity of designs. I forgot from my single line days. https://prismkites.com/product/eo-atom/

Kitexpert, how stiff are foil kites? Do they fold at the edge of the wind window? The pressure in foil kites are really low and the shape is formed by tension on the lines. Tires are well developed. I am sure that high pressure kites can be reliable and safe like tires. My concern is that Bruno has no injuries. So he can develop without delay. So we can enjoy his this next contribution to the sport!

(The hand surgeon that stitched my hand back together told me, with a wry smile, "you know nothing about refrigeration". Actually I did, but I did something very stupid. So I have professionals work on my AC then on.)
Sadly have to say that I too have been by consumed by kiteboarding and almost forgotten single line kites, and I designed the EO kite.

I think using pressure to combat the differences in the pressure the wing is experiencing means that you shouldn't need super high pressures, but it does effect more of the wing, Foils respond with wing tip luff but the rest of the wing is stable, an LEI will progressively luff, each you can catch and recover when piloting well. foils have a softer feeling reaction, LEI harder, a C-Quad had more power and control than either, until it didn't but was safer than the Nexus.
I look forward to the evolving of the wings we use, as I have been a crash test dummy for many experiments that didn't work then, but with current technology would've been a success. I still like foils for the snow and sand more than LEI, LEI on the water, will be interesting to see how this HP kite fits in.

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Re: High Pressure kite by Bruno Legaignoux

Postby tilmann » Mon Dec 17, 2018 8:30 am

I just measured the fronttube diameter of my 6 m Rally: 13.8 cm !! So it would be a big step forward if it had 10 cm. I think 10 cm diameter on a 6 m kite would work with 60 Psi and there would be no need for extra bridles.
Last edited by tilmann on Mon Dec 17, 2018 9:51 am, edited 1 time in total.

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Re: High Pressure kite by Bruno Legaignoux

Postby tilmann » Mon Dec 17, 2018 9:35 am

Now I measured my 9 m Edge. I find it shocking to just read the pure numbers: 16 cm ! :o
That means this "kite" is a flying rubber boat :cool2:

Bruno - help me, please !!!

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Re: High Pressure kite by Bruno Legaignoux

Postby spritrig » Mon Dec 17, 2018 10:40 am

I actually like a fat leading edge. Once you power up the kite, the canopy is giving a lot more drag. Right behind it is the powered up canopy which would have drag. I have kites with narrower leading edges than my fat LE 15.5m LF Solo. They are floppier! (Same number of line attachment points.) The bending moment of an inflatable beam is:

M = pπR^3 / 4

(page 3, equation 5) https://hal.archives-ouvertes.fr/hal-01008403/document

That means the bending moment goes up with the cube of the radius, but only linearly with the pressure. Lots of stiffness with radius or diameter, but less for pressure. Bruno is getting extra structure with more line attachments to the kite that the high pressure narrower diameter pipes need. The trailing edge needs to be low drag.

I like both of Bruno's LEI and HP designs. The speed records are with LEI kites!


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