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High Pressure kite by Bruno Legaignoux

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longwhitecloud
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Re: High Pressure kite by Bruno Legaignoux

Postby longwhitecloud » Thu Nov 29, 2018 11:45 am

cost is of big interest to me, following safety of course

LEIs cost about $260 (US) in quantity, a cquads cost about $40 if anyone remembers them!

no idea the factory costs of ram airs but when you look at the amount of labour and material ot mskes sense they are more expensive

what percentage saving on manufacturing/materials?

i remember the tarp material wipikas.. school kites. i also had a freeair up until last year .. it has no delamination at all after 17 years

i have rigged up an actual $10 8m2 tarp with a 5 line bar, not quite ridable but was surprised to find it flew, steered and i could loop it!

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Re: High Pressure kite by Bruno Legaignoux

Postby brunolgx » Thu Nov 29, 2018 2:58 pm

Honnestly I can't reply, you are talking design. The HP hose technology allows to design kites with low drag and with many design possibilities because of the flexibility of the frame. I'll post today a video showing one of these possibilities.

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Re: High Pressure kite by Bruno Legaignoux

Postby brunolgx » Thu Nov 29, 2018 3:17 pm

I was replying stefarius question in my previous post. Now longwhitecloud.
Tarp material was too heavy and if it was possible to make a light one it would be too fragile I guess.
I roughly estimate that the savings on materials and manpower will be 40%, so a small HP kite could be 600$ when a classic inflatable is 1000$. And if more powerful for same size, real savings will be more than 50%.
(remember that bow kites made the sport cheaper just because you need a 2 kite quiver instead of 3 or 4)

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Re: High Pressure kite by Bruno Legaignoux

Postby Qiter » Thu Nov 29, 2018 4:31 pm

Not sure this was referenced already? Eleveight seems to go in the same direction, there are some pics in the link below

http://forum.oase.com/showthread.php?t=174323

The author (kite designer Peter Stiewe) mentioned that he used the 4m kite in 18-20kn..

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Re: High Pressure kite by Bruno Legaignoux

Postby Faxie » Fri Nov 30, 2018 12:20 am

Qiter wrote:
Thu Nov 29, 2018 4:31 pm
Not sure this was referenced already? Eleveight seems to go in the same direction, there are some pics in the link below

http://forum.oase.com/showthread.php?t=174323

The author (kite designer Peter Stiewe) mentioned that he used the 4m kite in 18-20kn..
Looks like bridle wraps waiting to happen...

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Re: High Pressure kite by Bruno Legaignoux

Postby spritrig » Fri Dec 14, 2018 6:01 pm

I love the new kite you've been developing!

For safety, fill your pipes with water when you pressure test them. Liquids are incompressible and a burst should not create a dangerous explosion. You could also put the pipe in a container of water to measure changes in volume from stretching of your pipes before failure.
https://en.wikipedia.org/wiki/Testing_a ... _cylinders

I think you already know how to calculate burst pressure of a tube using Barlow's formula. Length is irrelevant. So you could do hydrostatic pressure testing on short pipes.
https://en.wikipedia.org/wiki/Barlow%27s_formula

I think safety is going to dictate an upper pressure limit of 100 pounds per square inch in a marketed product. "In order to breach the human skin the ejection pressure has to be at least 100 pounds per square inch (psi)8" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2532970/

Eardrums rupture at 5 psi. https://hypertextbook.com/facts/2007/ShemikaWhite.shtml

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Re: High Pressure kite by Bruno Legaignoux

Postby spritrig » Sat Dec 15, 2018 11:17 am

Hi Bruno. Here is a film on pressure testing airplane tires. They fill the tire with water. The stretching of the tire does cause the release of energy upon bursting with water, that they had to be shielded from. Testing with air in the 1960's was much more disastrous.

Be careful with pressurized gasses. I got a lot of stitches in my hand after a can of refrigerant gas exploded. I did something very stupid.

Increasing the diameter of struts would have a much lower drag penalty than increasing diameter of leading and trailing edge pipes.



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Re: High Pressure kite by Bruno Legaignoux

Postby kitexpert » Sat Dec 15, 2018 4:12 pm

spritrig wrote:Be careful with pressurized gasses.
That is true. But in this case there is not that much volume (conserved energy) so there isn't much danger. However there has been many deaths with exploding tires of heavy equipment. I was once at the same crossroad when a wheel of a truck exploded, my car got sand blasted and sound was really big.
spritrig wrote: Increasing the diameter of struts would have a much lower drag penalty than increasing diameter of leading and trailing edge pipes.
Too bad it is LE which needs most rigidity. Small struts can be a bit lighter in weight if they are smaller in diameter. But then they should have higher pressure than LE has. I'm not convinced TE strut because it sacrifices one LEI benefit, thin TE.

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Re: High Pressure kite by Bruno Legaignoux

Postby spritrig » Sun Dec 16, 2018 1:15 am

The energy stored would be the area of the pressure volume diagram cycle. Assuming a constant or average volume, the energy would be pressure times volume. https://en.wikipedia.org/wiki/Pressure–volume_diagram
A 2.5cm radius pipe that is 7 meters long is 13.7 liters. There are tires with about that volume. Multiplying 13.7 liters volume by 100 psi yields 9,476 joules of energy. (Type "(2.5cm)^2 * π * 7m * 100psi" into google to get that answer.) That's about 2.6 watt hours. It isn't energy that is the problem. It is power, energy per time. If you release 2.6 watt hours in a second we get (2.6 watt hours x 3600 seconds/hour) = 9,360 watts. Do it in half a second and we have 18,720 watts. More than sufficient to cause injury.

Long thin circuit batten(s) like used in popup shades could be used instead of inflatable beams on the leading and trailing edges. Wider struts could provide floatation with less drag penalty. This idea is now in the public domain and un-patentable. The circuit battens can be offset from the edge for safety, and there can be multiple circuit battens.
https://www.ikea.com/us/en/catalog/products/30228978/

Bruno's high pressure kite design also uses bridle system more similar to foil kites than LEI kite to give shape under tension. 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.

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Re: High Pressure kite by Bruno Legaignoux

Postby BWD » Sun Dec 16, 2018 6:18 am

now in the public domain and un-patentable.
No worries, it’s been done before anyway


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