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Double Chord Wise Ballooning...???

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Mossy 757
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Double Chord Wise Ballooning...???

Postby Mossy 757 » Thu May 25, 2017 2:38 pm

Can someone who knows what this means explain to me how this affects kite performance? This has been a feature of Flysurfer's marketing for a while and I remember in the Flysurfer testing and development video that came out earlier this year Armin mentioned this was an area of development for them, testing new materials for their ballooning characteristics.

gwicke
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Re: Double Chord Wise Ballooning...???

Postby gwicke » Thu May 25, 2017 5:11 pm

I think it refers to the normal tapering of panels at the nose & trailing edge, to reduce the ballooning locally, and thus reduce creases. Interestingly, the sonic race now has adopted a seam across panels on top of the nose, which lets them reduce creasing in that area further, by reducing excess fabric at the side of the cell in the strongly curved upper nose section. Ozone has been using those seams for a long time.

Edit: See http://laboratoridenvol.com/info/shapin ... 3d.en.html for a discussion of the issue & a few different options.

Mossy 757
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Posts: 1198
Joined: Fri Sep 11, 2015 5:10 pm
Kiting since: 2013
Local Beach: First Landing State Park, Virginia Beach Oceanfront
Style: Kitefoil
Gear: Delta Hydrofoil and board. Cabrinha Velocity 9m, Flysurfer Sonic2 11m, Elf Joker-7 15m

Re: Double Chord Wise Ballooning...???

Postby Mossy 757 » Thu May 25, 2017 5:26 pm

So the kites are basically sewn "tight" in order to account for the outward deformation that occurs when the cells pressurize?

gwicke
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Re: Double Chord Wise Ballooning...???

Postby gwicke » Thu May 25, 2017 11:26 pm

Mossy 757 wrote:
Thu May 25, 2017 5:26 pm
So the kites are basically sewn "tight" in order to account for the outward deformation that occurs when the cells pressurize?
Yup. The idea is to keep the fabric tight & crease free by a) locally increasing the fabric tension between ribs, and b) shortening the fabric closer to the ribs with tapered, horizontal seams. Mini-ribs also help address the issues associated with ballooning near the trailing edge.

gwicke
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Re: Double Chord Wise Ballooning...???

Postby gwicke » Fri May 26, 2017 3:50 am

On the R1V3 Ozone now added a second horizontal seam for even finer control over the shaping in the upper nose section. They call this "Double Transversal Shaping".

I am a bit sceptical about the second seam. It is positioned right across the laminar section of the profile. The turbulence caused by the seam itself could partly negate the gains from less creases near the rib. Additionally, the sewing tolerances would be even more critical with more seams. Any minor imprecision could introduce creases and discontinuous shaping of its own.
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Mossy 757
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Posts: 1198
Joined: Fri Sep 11, 2015 5:10 pm
Kiting since: 2013
Local Beach: First Landing State Park, Virginia Beach Oceanfront
Style: Kitefoil
Gear: Delta Hydrofoil and board. Cabrinha Velocity 9m, Flysurfer Sonic2 11m, Elf Joker-7 15m

Re: Double Chord Wise Ballooning...???

Postby Mossy 757 » Fri May 26, 2017 2:47 pm

Very interesting, I see your point about the seams, I haven't heard anyone complain of a bad R1V2 in terms of build quality at all, so hopefully they're sparing no expense in that regard to get this stuff right.


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