High Pressure kite by Bruno Legaignoux

[kitexpert]

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.

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.

[edt]

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.

[tilmann]

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

[kitexpert]

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

I have even more in my road bike 23mm tires. This "problem" or fear should not be exaggerated

[spritrig]

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.)

[FarQueLot]

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.

[tilmann]

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.

[tilmann]

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

Bruno - help me, please !!!

[spritrig]

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!

[tilmann]

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.

supports my feeling that 5 cm diameter is not enough. But as I said before: A 6 m HP-Rally with 10 cm diameter would make me totally happy already.