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 Post subject: Why not two smaller LE instead of one big LE???
PostPosted: Wed Mar 05, 2003 8:08 pm 
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Location: Bremerhaven/Germany
When i couldn´t sleep last night a question came to my mind. :idea:

Why did nobody untill today try to build a kite with two smaller/thinner fronttubes (one behind the other) instead of one thick fronttube. :?:

Espacially the big sizes should be faster, when there is no big LE that is troubleing the airflow. :!:

Any comments?


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 Post subject:
PostPosted: Wed Mar 05, 2003 8:40 pm 
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I don't think the fronttube is a major problem, really.

The leading edge of a kite has to have a reasonable diameter, in order to give a kite lift, and at the same time it offers good stall characteristics (wont stall, only slow down).

To get rid of the front tube is not really a goal, unless it is WAY too thick.

But I don't think it is, really.

If you take a look at foils from paragliding, you'll see that the leading edge size is usually really huge.
Despite they have the possibility to construct it much thinner - they don't !

A sharp leading edge is useless, unless you are flying supersonic aircrafts.

And even the fastest kites, in lots of wind, are relatively slow flying objects.

The front tube diameter seems to have decreased slightly the last years, and on some kites replaced with more camber instead.
This gives a kite with good upwind performance (high L/D), but still not very good in overpowered conditions (can't depower much).

The object for good jumping (which is the goal for all kiters I assume), is to get a very fast turning responding kite, which is relatively fast flying, but most of all also has the ability to produce lift at low speeds, and huge AOA.
In case you want to slow down and float to the surface, this is extremely important - besides that it gives you the ultimate hangtime in normal jumps.

This is why the LE tube is good in fact, up to some extent (size).

It is not as bad as some want's it to be (I don't know why some say its so bad...)

We can see how good it works, and how fast the kites are flying today, while they still are able to lift insanely when flying slower.


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 Post subject: Re: Why not two smaller LE instead of one big LE???
PostPosted: Wed Mar 05, 2003 8:58 pm 
Fabe wrote:
Why did nobody untill today try to build a kite with two smaller/thinner fronttubes (one behind the other) instead of one thick fronttube.


Who said nobody has tried it? :wink:
I agree with Peter though. The state of the art is not bad at all.

What's great is that it will keep getting better. Whoever thinks tubes have plateaued is delusional.
8)


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PostPosted: Thu Mar 06, 2003 1:15 pm 
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Peter_Frank wrote:
I don't think the fronttube is a major problem, really.

To get rid of the front tube is not really a goal, unless it is WAY too thick.


A round tube of a given thickness has about ten times the zero AoA drag of a 33% t/c foil of the same thickness.

Leading edges will get smaller again in 2004.

I have flown 7 different prototypes with different leading edge diameters. ALL the kites with the smallest diameters, were the highest preforming. When you walk around the beach, just think, in this case smaller is better. :D Snicker at kites with fatter leading edges, because they are old school.

Quote:


If you take a look at foils from paragliding, you'll see that the leading edge size is usually really huge.
Despite they have the possibility to construct it much thinner - they don't !


They are double surface, that's the difference.

All hang gliding round spars have fairings.


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PostPosted: Thu Mar 06, 2003 2:10 pm 
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I remember a while back some company tried having two bladders in the front tube, the idea that by having a thinner one infront of the thicker one you could make the front more of an elliptical shape.

at the time it was supposed to be the next revolutionary step (if you believe the hype) but I guess any benefits were far outweighed by the extra weight and pumping required.


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 Post subject:
PostPosted: Thu Mar 06, 2003 2:11 pm 
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Location: the best place to kite in the world
Small leading edges may be good for you light weights. But take one heavy dude throw in a supper hard heel side carve and fold goes the leading edge. Or take one super heavy dude throw in a gust and good edge ability and fold goes the leading edge. All this on a well pumped heavy segmented LEI kite. Trust me....

So any manufactures out there please dont forget the big guys flying kites.

Cheers shane


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 Post subject:
PostPosted: Sat Mar 08, 2003 6:05 am 
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Actually, this is already being done. I haven't seen it myself, but last year Gaastra was making prototypes of this, testing them here in the Gorge, and possibly even working on patents. It was kind of top secret until recently, but the last time I talked to people from Gaastra it seemed that it was no longer a secret, so I don't think I'll get too much flack for posting this here. The last report I heard was that the newest prototypes are really dialed in, and this spring or summer they might even let some of us regular folks try them.

I rode Wipikas for 3 years (now I've got BlackTips), and in 2001, there were 3 different generations of the AirBlast. There were multiple variables in each generation, but the one with the smaller leading edge tube seemed better to me, although a bit too much jellyfishing (2 tubes apparently solves this). We can argue all we want about aerodynamic theory, but in the near future we should be able to put theory to the test, and see if this truly is an improvement. I think there is still room for huge improvements in inflateable kite designs. I'm anxious to see where this goes. If you like lower aspect kites with really deep draft for doing technical tricks, this might not be an exciting innovation, but for people who like really fast high aspect kites that deliver a big power spike when sined, this could be really cool. It's on the way, so time will tell.

Spencer
Hood River


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 Post subject:
PostPosted: Sat Mar 08, 2003 7:45 am 
small -strong kite is avery good philosophy ,but how you do it thats the main issue .
one way is to construct awide diameter tube easy to make -but not effective (alot of draft) .
differrent way is to make adeep kite with asmall tube, the rin0-2 built like that , you cant make much deeper kite since the top wind range will be much smaller and only 90+ kg people will be able to ride it ,maybe you can reduce the diameter of the front tube (rino 2) and with avery precise designing it will not jelly fish (i think this kind of designing will use more material on the tipps and make them longer) but the kite will be very hard to relunch and very tearable.
third way is aduble tube,very good idea ,with some question -how the extra weigth will efect the kite ,with big kites the extra weigth can be significant but with the med and small kite it can be the next revolution ,on problem is not the extra weight but the location of the extra weith ,that can lead to unstable kite ,every time the kite will stall ut will fall forward/
last way is to make mid- ar kites ,it will not make asmall and strong kite but the kite will not be to-long (from tip to tip)so the diametr of turning will be smaller and the kite will turn faster/
all of this is true for tube kites ,the potential of afoil kites on the same mattr is much bigger ,still they have to go long way changing there thinking from para-gliders to kite-surffing ,but the potential is there


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