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Objective test of kite performance!

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ancsi@hotmail.com

Objective test of kite performance!

Postby ancsi@hotmail.com » Thu Dec 02, 2004 3:35 am

.... I just do not get it. Everybody is so emotional about which kite is the best. How come that no one came up with an objective way to test a kite's performance?
Get into a windtunel! Pump up a size 12 kite to factory specs (...every brand has a size 12), weigh the kite, measure the rigidity, measure the pull at a given windspeed, measure drag, check how close it gets to the edge of the wind-window...... The same way it is done with a car. If a kite aces those test it can cut all the BS about subjective mambo-jumbo..... What do you think?
steven

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consumer
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Postby consumer » Thu Dec 02, 2004 3:38 am

do you have any idea how expensive wind tunnel time is?

even major car manufacturers budget to the absolute minimum duration of tunnel time, its expensive as hell, i dont know the exact figures i just know its not an inexpensive deal or so i was told.

and even if it was moderately priced i dont think these low budget mag companies could pull it off, lets face it, its a 2 month/issue ratio.

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Postby hortobagy » Thu Dec 02, 2004 3:44 am

Oh, come on all the kite companies claim that their design is wind-tunel tested..... It can not be that expensive. Some University could do it as a student project.
I think the reason it is not done beacuse the results would be the same. Same material, same concept and no difference between the years.... the marketing guys would not be able to promote the same old stuff as revolutionary, hyperperformance, super, extra, etc.

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Postby DrLightWind » Thu Dec 02, 2004 4:30 am

hortobagy wrote:I think the reason it is not done beacuse the results would be the same. Same material, same concept and no difference between the years.... the marketing guys would not be able to promote the same old stuff as revolutionary, hyperperformance, super, extra, etc.
hortobagy,

I agree there is not much difference. The difference is only 4 to 1 or 5 to 1 of L/D,
than it's still only the half of what hangliders used to have 8 to 1, 20 years ago.
So what the hell is this? That means kites are very poor design. No penetration and too much drag.
So that's the reason the range is so narrow and when overpowered it's not the lift but the drag what we feel.

DrLightWind

hortobagy you must be from Hungary, right?

Any type of kite could look "gay" because of the rider's abilities;
and any type of kite could look "cool" because of the rider' abilities!
It's a mistake to be divisive,
there are many ways by many brands to get the same feeling of fun.

Flown Arc type, Foil type and L.E.I. kites and
found neither one are perfect as people, especially the L/D;
But each one has it's good point of applications.

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Postby harakiri » Thu Dec 02, 2004 6:11 am

Is kite supposed to be tested as attached with full 30 m lines? What diameter the biggest wind tunnel have?

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Postby Elia » Thu Dec 02, 2004 8:17 am

The problem is what you are measuring is often a subjective quality. One person wants a stable kite another wants one that turns quick or what ever characteristic you want to describe. A wind tunnel test is only going to give you numbers how we interpret those numbers is another matter. Also you have the problem of real life conditions i.e. gusty wind, I wish I could go to my local beach and say I want 17.8 knts for 2 hours… please. It’s just not like that. You have so many factors that are not dependent on the kite that it would be a very difficult thing to have objective testing. I personally think it’s better to have a bunch of people of differing abilities test the kite and that way you have a general Idea about the kites and then test fly them yourself. I think it’s the only way.

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Postby spork » Thu Dec 02, 2004 9:24 am

I have to agree that I'd like to see some hard data. I realize there are a number of parameters that might be difficult to test, but you could certainly map the polar of the kite readily by mounting and instrumenting the bar in the bed of a pickup and driving at specific speeds while recording the data. This is done by the hang glider manufacturers association (HGMA) in the U.S. to pass the HGMA structural and stability tests (but not performance). I believe it would be easier to do with a kite than it is with a hang glider. You typically do these tests in early morning to get the smoothest possible air.

You could certainly get the complete polar (basically the L/D over a range of speeds and A.O.A.) without much difficulty. I think turning rate could be measured with some accuracy as well fairly readily. Really no need for a wind tunnel for something like this.


The question is: who has enough motivation to do this? I suspect the manufacturers aren't in a hurry to start competing on cold hard data.

RC

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Postby kitebored » Thu Dec 02, 2004 9:42 am

it's like asking which paintbrush is the best.

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Postby jakobjth » Thu Dec 02, 2004 11:58 am

At least the mags/reviewers/brands could do an effort and weight the kites (at least for tube kites this should indicate some of the performance in light winds...). And why don't the brands include the lift coefficient in the specs of the product & also the L/D ratio? If this was measured we would avoid all the xxx posts on the tube vs foil vs arc subject :wink:

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Postby kitefrog » Thu Dec 02, 2004 12:04 pm

Let's fACE IT.

Take a 12m kite, same cord and AR. Similar front tube diameter...
They are all the same!


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