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Kiteloop Kite Deformation: Bridled vs. C

 
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skilja

Since 02 Jan 2008
75 Posts

 



PostTue Aug 30, 16 10:28 pm    Kiteloop Kite Deformation: Bridled vs. C Reply with quote

The question is, how do bridled vs. unbridled kites change shape during a kiteloop, and thus change the characteristic of the loop?

I've heard differing opinions on this from knowledgeable people ... and also internet speculation.

One perspective is that the bridle keeps the kite from deforming and thus creates a slower and harder pull at the bottom of the loop. Whereas the traditional C-kite deforms as it moves through the loop into a kind of corkscrew shape that funnels wind through/over the canopy.

The contrasting perspective I've heard is that those two characteristics are actually reversed and it's the bridled kite that twists into a corkscrew shape, and the C-kite that holds it's shape through the loop.

Does anyone have a definitive answer for this?

Are there any kite design/engineering links out there about this?

Thanks!

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consumer

Since 28 Nov 2010
406 Posts
banned
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PostWed Aug 31, 16 6:54 am     Reply with quote

if twist is related to torque and torque is force at a distance from the center of mass, then we have a kite applying a force at multiple points along the leading edge vs a kite that applies that same total force, but at a single point on the wing tip.

Assuming the center of mass is not at the wing tip and is maybe, near the center of the leading edge, it sounds like more torque is applied to the kite via a single attachment point at the wingtip than if it were distributed along the leading edge via a bridle.

*i'm ignoring the trailing edge attachment points because I am assuming most of the tension/force is in the front lines.

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bigjohn

Since 13 Mar 2012
663 Posts

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PostWed Aug 31, 16 7:04 am    Re: Kiteloop Kite Deformation: Bridled vs. C Reply with quote

skilja wrote:
The question is, how do bridled vs. unbridled kites change shape during a kiteloop, and thus change the characteristic of the loop?

I've heard differing opinions on this from knowledgeable people ... and also internet speculation.

One perspective is that the bridle keeps the kite from deforming and thus creates a slower and harder pull at the bottom of the loop. Whereas the traditional C-kite deforms as it moves through the loop into a kind of corkscrew shape that funnels wind through/over the canopy.

The contrasting perspective I've heard is that those two characteristics are actually reversed and it's the bridled kite that twists into a corkscrew shape, and the C-kite that holds it's shape through the loop.

Does anyone have a definitive answer for this?

Are there any kite design/engineering links out there about this?

Thanks!


I am definitely not a kite engineer... So hopefully more knowledgeable will throw in answers.

That being said, I believe that there is more than kite design in play here. Technique and size/relativeWindSpeed are primary factors as well.

Often times when quickly looping a kite we are actually "stalling" the inside portion of the kite which reduces the power of the loop considerably.

Consider This:
While pointing your board straight downwind you can continuously loop your kite very low to the water in tight loops (switching loop direction after 3 bar wraps) with the kite completely in the wind window and your kite pull is rather minimal.

However, if instead you take giant rounded loops where your kite comes up high and then goes through the wind window with lots of speed the pull of the kite is significant.


My thought is that at some point during the larger loops your kite becomes efficient and actually creates lift for the entire kite rather than part of the kite back stalling throughout the loop.

Now in an attempt at an opinion towards your question...

I believe it is likely that the faster turning characteristics of a C kite will allow it to reach the point of efficiency sooner (thus you are more likely to have an efficient loop with a C kite). However, in the event a kite with a more bow shape does reach the efficiency stage of a loop it will have more pull than the C kite had.

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Justsmile

Since 20 Jul 2009
1523 Posts
Not Portland
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PostWed Aug 31, 16 8:40 am     Reply with quote

Friend Alex Bloechinger on crack book. He does quite a bit of kite design for slingy and could give you actual answers instead of us hypothesizing!!!!
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bwd

Since 04 Aug 2007
385 Posts

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PostTue Sep 06, 16 5:18 am     Reply with quote

During the loop, a c kite increases projected area (=more power) in the wingtip on the outside of the loop, which is also reaching a higher airspeed - the long wingtips come into play. While the kite is looping, the outside half takes a more open arc shape and pthe inside half of the canopy is more u shaped, so the kite more closely resembles and acts like a propeller. With a bridle, this effect is less, especially when the arc is not as deep, i.e. more open c and less u shaped, with the bridle locking the arc shape in to some degree, usually a large degree (but it depends on the bridle).

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bigjohn

Since 13 Mar 2012
663 Posts

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PostTue Sep 06, 16 6:12 am     Reply with quote

I guess all engineering theories could be put to a test.

Wouldn't a downwinder be the perfect testing ground?

What do the winners of the BOTG blowout ride?

... this isn't a seeded question... I honestly don't know as this race occurs during my busy season...

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jperry

Since 07 Nov 2008
188 Posts

Stoked



PostTue Sep 06, 16 7:17 am     Reply with quote

Kites work on the theory of wing warping. The right brothers used this.

Bridled vs un bridaled.

Bridals allow you to support different wing shapes and allow for different cg points on a kite.

You can control the twist or warp of the leading
Edge with bridals and threw different leading edge thicknesses and constructions.

c kites lift in a c shape giving you a more locked in feel. You can put a 5th line or bridal on it dispersing the load freeing the wing tips giving you a lighter turns feel.

A more open kite with bridling and pulleys will feel lighter and turier. Depending on the cg and geometry. This can all carry. When you take away pulleys your start getting more direct feels and your load distrbutation gets more vital. Each line of your bridal is now more dedicated to its task. Cg points now become a lot more important to how the wing was designed. I could go on. I gotta go to work though. Sad.

I have experienced more collapsing problems with bridaled kites.. Due to load dispersion. I have not had much with c kites.
But I have not played with many c kite Geometrys

In general kites collapse either from under inflation and turbulent air flor from the lei design or from improper inflation and load distrbutation in the bridling.

Kites work on the same general theories as wings. I have been playing with load testing and other types of data collection.

I have pretty limited knowledge in revalance to what's out there and what could be done with time and
Money.

I know thekiteboat homies in San Fran have funds and full time jobs doing this.

Tony Logosz is local and a good guy to talk to about it
Alex Bloechinger is good to.

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