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helix vs cult

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ScottM
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Postby ScottM » Mon Jun 11, 2007 3:58 pm

I'm sure when looking head on the kite has naturally curved struts.

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funalex
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Postby funalex » Mon Jun 11, 2007 4:33 pm

BWD wrote:
the canopy must be arc shaped,
Apparently not.
What I wanted to say is that a naturally arc-shaped strailing edge (the trailing edge of the helix is arced ?) can't mach a straight trailing edge.
MissionMan wrote:May want to rethink that argument, you contradicted yourself.
Also interested, that the last time Best and SQ blew a concept out the water on this forum, they ended up making one themselves.
Which argument ? could you precise ? ... I don't ride Best, they are not the perfect choice I think, but I just precise that the inverted pulley used on waroo, introduced by globerider, on sonic...and so...are great device to increase stability even if the weight on the front part is important.

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Postby sq225917 » Mon Jun 11, 2007 4:59 pm

the front pulley itself doesn't increase stability, it just allows for a wider range of AOA from any canopy profile. the stability comes from how you use the bridle to support the profile shape and control the COE positioning relative to AOA.

There are better ways to stabilize a bridled kite than a single pulley.

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Postby eldadgold » Mon Jun 11, 2007 5:42 pm

eran m wrote:when the center of pressure(effort?)move back > more bar pressure?
:?:

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Postby funalex » Mon Jun 11, 2007 8:50 pm

A single inverted pulley like on a "tribalou"...is really more stable than anything on tube kite market...there is an auto regulation between bridle on the front part, and bridle on the back part. If you add stopper like on waroo2, it break the balance.

We could easily imagine that without stopper the kite loose too much AoA to be Stable, but it's the contrary, don't put stopper and the kite will be very-very stable.

for eldadgold...yes, moving backward the COP make the kite pull more on backline...but bakcline are really far, I don't think it pull a lot.

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Postby tautologies » Mon Jun 11, 2007 9:23 pm

eldadgold wrote:
eran m wrote:when the center of pressure(effort?)move back > more bar pressure?
:?:
No not at all. The bar pressure on 1:1 was SUPER light.

Also I don't think there is a natural shape for a kite...it will be whatever it is designed to be. I think the kite looks really great, and the reasoning behind the kite seems good to me. I am no aerodynamic expert, but moving the weight further back on the kite would prevent it from overflying. ALso the shapr of the leading edge I would prevent it from inverting. It seems good to me. The straight canopy does minimize flutters on the canopy...actually it looked dead solid even in gusty Maui wind.

I forgot to look at details regarding pulleys and such on the kite, so I can't really comment on that. Only that kite felt really nice, and solid...

A.

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Postby Nino_fs » Mon Jun 11, 2007 9:32 pm

Ok so from reading the post of the guy or girl who has flown this kite he makes it sound as if the leading edge is made up of perfectly straight sections :o .

I really hope not because a kite does have a natural shape which is the arc shape. It is completely a matter of physics when holding a sheet in the wind by the two ends it makes a smooth continous even curvature between the two points. To make it do anything else you need rigid structures or bridles.

Which is no problem at the leading edge but is impossible at the TE because the only thing supporting those points is the struts which just are not strong enough.

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Postby tautologies » Mon Jun 11, 2007 10:13 pm

Nino_fs wrote:Ok so from reading the post of the guy or girl who has flown this kite he makes it sound as if the leading edge is made up of perfectly straight sections :o .

I really hope not because a kite does have a natural shape which is the arc shape. It is completely a matter of physics when holding a sheet in the wind by the two ends it makes a smooth continous even curvature between the two points. To make it do anything else you need rigid structures or bridles.

Which is no problem at the leading edge but is impossible at the TE because the only thing supporting those points is the struts which just are not strong enough.
oh, oki, I think I understand what you mean. Well, no they are not perfectly straight, but they are way straighter than I have seen before. Also remember that I just had a few short views / runs on the kites..but my overall perception..and I'll modify my choice of words for you ;-) are straighter planes...you have the leading edge sectioned up using what I remember as straight sections...maybe except for the wingtips..but at least more so in the center of the kite. The point of the straight leading edge sections as far as I know was to avoid loosing energy in fluttering canopies, and the kite really looked super stable. Also I am guessing that the flatter profile would be able to generate more lift as it is more efficient where the lift is created. Also if you look at wings in nature, they actually do have straight lines, surely if it was more efficient with a curing profile, wings in nature would be that way?
The same way as the Sigma shape is I guess looking at some of the pics the trailing edge is more curved, but in all my pics the canopy is perfectly straight, and didn't even have a wrinkle on it.

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Postby munteruk » Tue Jun 12, 2007 4:05 am

I think the matching of the LE & TE shapes will be an issue for this kite. Concave TEs are a good idea because they allow the TE to be pulled into a flatter shape to match the bridle supported LE. With the helix, the additional area put into the center section of the TE will have the effect of flaring the TE up in the center. You can see it in some of the promotional photos. Look for a photo from behind where you can seen the profile of the TE & LE and its possible to see a C-shaped TE but a flatter LE.

Does this really matter? I don't know. I would have thought that an TE that matched the LE would be the lowest drag profile but kites are complicated and they operate in many different air flow modes. Maybe a difference between the LE & TE doesn't matter?

Anyway - the proof will be in the testing. Discussions before public testing are interesting but what really matters is how it flys. :thumb:

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Postby tautologies » Tue Jun 12, 2007 5:15 am

the proof will be in the testing. Discussions before public testing are interesting but what really matters is how it flys
Agree!!!!

A.


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