Na, i'm taking the piss cause a kite cannot be compared to an aerofoil, wing, handglader, paraglider... The closest thing it could be compared to is a sail/spinniker...

regards browneee

ps, we're talking about bloody kites fellas... go get some wind will ya...

reading all these posts by you want to be physisists and looking at these formulas that are way off is interesting, i would love to live in a place where these messed up rules apply.
we have this crazy version of the kinetic energy of moving air, which i suppose would be ok if it were right, but after that emu says **** like a kite half the weight will have half the momentum when it hits the water, i cant believe i passed my exams, i didnt realise that you could just take the momentum of the air behind the kite out of the equation. this is great news because it probably applys to other things like, if a truck gets a bumper bar that weighs 0kg, i could get hit by it at 100km/h and it wouldnt even hurt because we can ignore any factors we feel like.
why would you be talking about the kite and rider as one system when talking about the weight of light wind kites, that is retarded, i cant be bothered saying why.
greg

Build two kites identical in size and design based on the Hellfish model.
Kite A is to be constructed from dacron/rip-stop,
Kite B is made of lighter, stiffer cuben fibre.

Test them together on the same day, same beach using the same board and rider in the same wind conditions.

I'm guessing BEST has already conducted this experiment and found Kite B to be more efficient.

But is the efficiency increase great enough to warrant a drop in kite size (say 2m min) for that given wind speed??

quote:

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Originally posted by waveslave

Build two kites identical in size and design based on the Hellfish model.
Kite A is to be constructed from dacron/rip-stop,
Kite B is made of lighter, stiffer cuben fibre.

Test them together on the same day, same beach using the same board and rider in the same wind conditions.

I'm guessing BEST has already conducted this experiment and found Kite B to be more efficient.

But is the efficiency increase great enough to warrant a drop in kite size (say 2m min) for that given wind speed??

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I'm going to have to say yes to this... As we've done it... And we are saying that...

we're not talking about disproving the laws of physic's, simply challenging the way everyone thinks kite's fly...

quote:

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Originally posted by Emu

If the kite is close to the water, the board is supporting near 100% of the rider's weight. Where the kite is just hauling you along the weight of the kite is going to make little difference. Its when you go to turn the kite or make it change direction or speed in some way that you get the benefit.

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Ok, comes back to this...

If the kite is close to the water's surface, you're obviously hooking along... Now as you said, almost all the riders weight is being support by the board skimming across the waters surface.

Therefore the kite would not have to do as much work to keep you on the plane as it would require to get you on the plane...

Now to get you on the plane it would require:

force
----- = Accelaration
Mass

Now to keep you on the plane it would require:

Mass x Velocity = Momentum

Ok now we're making this claim,

quote:

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"up to 80% lighter than a traditional kite made from polyester rip-stop & dacron."

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So being 80% lighter that would indicate it has less "mass" ?, therefore it would require less "force" to "accelarate" it than a traditional polyester rip-stop kite in the same wind conditions.

So putting the reduced "mass" back into the above formular and keeping the same "force" that would equate to better "accelaration" .

Further to this, having better "accelaration" and using the rider as the "mass" would that not indicate the kite would be able to maintain the "momentum" easyer...

my head hurts...

regards browneee

quote:

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Originally posted by jan

when the kite turns the speed at which it can turn or the speed at which it could pivot about the kiter (move across the wind window) could be significantly altered by a lighter kite

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Yeah I agree,

force
----- = faster acceleration...
mass

quote:

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its not that the kite is lighter therefore faster/stronger or can generate more force, but that it is lighter, faster, more efficient and able to fly in such a way that the forces it can generate are "better"

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I think you just said the same thing twice, which again would equate to...

force
----- = faster acceleration, better performance ?
mass

regards browneee

ps, I also want to say this, I belive that everone has a right to an opinion, in my replies in this thread I'm not trying to convince you that I'm right as I'm not interested in that. I simply enjoy chatting about these ideas and seeing other points of view I find it helps increase my own knowledge and understanding on these theories...

what might be more interesting, is that once you jump and are airborne, the kite *would* be acting more like an airfoil as you "glide" back down...

now *here* having a lighter more efficient airfoil could be far more (directly) apparent

quote:

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Originally posted by kitepower

quote:

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Originally posted by jan

the "weight" of the kite and F=ma acting on the rider would concern the m of rider+kite (the whole system)... a couple kilos has a small effect

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Just thought I would throw in another perspective.
The kite is sometimes supporting rider weight, but most of the time it is pulling against the the force exerted on it by the riders board edging skills/strength and a percentage of the riders weight, would you agree?
Then a lot of the "better" has to do with rider preference and skill from my perspective, as I don't know jack about all the physics compared to some of you guys.

What I have seen at the beach is that rider A who weighs 65kg is out on a kite size and having fun, that rider B who weighs 90Kg is afraid to launch.

Have fun!

Cya and

Goodwinds

Steve McCormack
(who will be in Vanuatu tonight)

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Yeah well thats what you have to do, Physics has its place however practically you have to observe what happens out side of the controlled environment and what really happens out on the ocean/river and in the gusty winds...

regards browneee

quote:

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Originally posted by NorthSide

MAN I LOVE BEING RIGHT!!!

P.S FACT! The Right Brothers tested there wing designs by flying them as kites first...

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FACT: It was the Wright Brothers, (Orville and Wilbur).

Please show the respect our kiting forefathers deserve!

NorthSide said

quote:

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Oh dear I am bathing in cleverness!!!
Thankyou, thankyou... LOUD APPLAUSE

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He also said on the NASA Thread

quote:

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Something interesting to note is that aspect ratio is a powerful indicator of the general performance of a wing. Wingtip vortices greatly deteriorate the performance of a wing, and by reducing the amount of wing tip area, making it skinny or pointed for instance, you reduce the amount of energy lost to this process, and increase the lift generated by the wing. This is why high performance gliders have very long, skinny wings; with no engine power, they must be as efficient as possible in every respect in order to stay aloft.
Most birds have wings with a wide aspect ratio, and with tapered or elliptical tips. This is particularly noticeable on soaring birds such as the Albatross and Eagles. In addition, the V-formation (echelon) often seen in flights of geese, ducks and other migratory birds can be considered to act as a single swept wing with a very high aspect ratio - the vortices shed by the lead bird are smoothly transferred to the next and so on. This confers a huge efficiency advantage to the flight as a whole - perhaps as much as a 100% improvement compared to a single bird in flight. Note that the usual common explanation of the V-formation - that following birds are "shielded" from air resistance by the bird in front - may be misleading. While birds do "take turns" at being the lead bird, it is probably to give those at the tips a rest - they are the ones that will experience the most drag when the vortices are finally shed.

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Which was pretty unfair coz he neva once told all us dum schmucks that he had a job actually writing definitions on this web site www.answers.com/search?q=aspect-ratio - where his quote above appears word for word

I'm sure we all apologise for basking in your superiority - but we must The alternative thought that you are a plagiarist is a thought that we all couldn't bear

From the same site - Self Expression "Expression of one's own personality, feelings, or ideas, as through speech or art"

Have a clever day

I'm with you Later