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Free kite plans on GitHub

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kiteykitekite
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Re: Free kite plans on GitHub

Postby kiteykitekite » Tue Mar 17, 2020 1:34 pm

kjorn wrote: Thin tube requires much higher pressure. Also changes the flight characteristics.
Really with increased bridles you can't keep the pressure lower?

Thinner will fly better, that is the point. Lighter and less drag.

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Re: Free kite plans on GitHub

Postby kk0239 » Wed Mar 18, 2020 1:20 pm

Any chance of updated documentation?

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Re: Free kite plans on GitHub

Postby kjorn » Thu Mar 19, 2020 3:19 am

kiteykitekite wrote:
Tue Mar 17, 2020 1:34 pm

Thinner will fly better
In your imagination this happens. In real life - no.

Now, please provide some evidence that a super thin LE flies better.

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Re: Free kite plans on GitHub

Postby kiteykitekite » Thu Mar 19, 2020 12:46 pm

No you have that wrong. In real life it does, in your imagination it doesn't.

You can find examples of thin carbon kites, like the peterlynn cquad and many others. Bruno is developing a thin LE. And despite all that the principles of aerodynamics disagree that a thick tube would be better. I wouldn't expect kite designers to grasp those principles though, given they can't understand things like appropriately weighted bridle lines, splices or something better or more appropriate than a chicken loop. Industry is obviously not high paid enough to generally attract intelligent people. To me it is just a hobby. Surprises me though in spite of hints a plenty they still can't work things out or are incredibly slow. Dumb is dumb.

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Re: Free kite plans on GitHub

Postby Matteo V » Thu Mar 19, 2020 1:57 pm

kiteykitekite wrote:
Thu Mar 19, 2020 12:46 pm
No you have that wrong. In real life it does, in your imagination it doesn't.

You can find examples of thin carbon kites, like the peterlynn cquad and many others. Bruno is developing a thin LE. And despite all that the principles of aerodynamics disagree that a thick tube would be better. I wouldn't expect kite designers to grasp those principles though, given they can't understand things like appropriately weighted bridle lines, splices or something better or more appropriate than a chicken loop. Industry is obviously not high paid enough to generally attract intelligent people. To me it is just a hobby. Surprises me though in spite of hints a plenty they still can't work things out or are incredibly slow. Dumb is dumb.
Kkk,

You're lost right out of the gate, buddy! You first need to define "better". Thicker foil sections, and thicker leading edges have their place. The world is full of different Wing shapes because different Wing performance characteristics are desired in different situations.

And thinner is not always better. Even high-performance airplane Wings do not use a sharp Leading Edge with a microscopic tube at the front. So this defines the parameters of sharp being too small of a round section, and on the other end, there is too large of a round section. In between is a wide range of performance characteristics desirable to the unique application of kites.

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Re: Free kite plans on GitHub

Postby kiteykitekite » Thu Mar 19, 2020 9:59 pm

So better, in the same way I believe you define it, a faster kite. So a kite with also more range, depower, lift and speed from less drag. But also less weight and associated benefits. But hey if you look back I did say that just in less words, those being "lighter and less drag".

So a number of things when you think of a thicker airfoil. There is a lot of misinformation on airfoils. A thinner airfoil is better, but for a number of design limitations thicker airfoils are used. Kites are interesting in they are basically just a piece of flexible cloth, of a thickness that approaches almost zero. They take their shape mainly by how they interact with the wind. Foil kites rely solely on the wind to affect their shape, albeit in interesting ways of storing higher pressure areas to work against the lower pressure areas, but so too do inflatables have to take a shape against the wind, as they are mainly loose fabric.

The tube has never been considered a good aerodynamic structure. Now the tube with a skin on one side is a bit different, particularly with the skin on top and as well tubes at differing sizes can have vastly different aerodynamic properties at different air speeds. So saying that you can have a reasonably thick tube that for general kiting is not so bad. But in general to make it thinner will improve the aerodynamic properties and that is not to include the weight benefit too.

I am not talking about sticking razor blades on the LE. Though if you could a maintain direct heading of the LE into the airstream then yes a Razor blade would be better. That is not possible really though, a variety of AoAs will see the LE too change angle. The only slight exception is where like with foils you can alter camber so much that in some realms the LE can remain static. But you add in the complications of flight and particularly a kite which changes AoA mainly from window position and then no a sharp LE is never going to be best. Having said all that there is a great difference in scale from a razor to a 1inch, or 6inch or 12inch tube. What are the exact benefits? Well it would have to be tried. Ozone originally made an attempt. To me they seemed good, but from what I was told they were too hard to relaunch. Strange should you give these people a Peak to use....From what I have seen of the bridle designs from most tube designers is they couldn't design what I am thinking. Which is to use a bridle design and density, like used on something like a Peak, so you can get the tube really small, maybe 2 inches, maybe 3, maybe 4. Maybe you go higher pressure, maybe you use thicker material. There is a lot of speculation, but it is not silly because thin carbon tube kites work and so too do many bridles on foil kites. If you make bridles out of 3mm ropes no this will not work. But kite designers that do and have done that are just showing how little they understand. Dumb is dumb.

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Re: Free kite plans on GitHub

Postby kitexpert » Fri Mar 20, 2020 3:09 pm

LE thickness is not all about when kite is flying but also when it doesn't. For example in some relaunch situations LE is not supported by the bridle and if it is very thin it will bend and buckle. If thin LE is compensated by having more bridle kite becomes more complex and also drag increases.

When kite changes AoA thicker more rounded LE makes kite behave more predictable, powering up, stalling and reacting to gusts is not as aggressive as it is with thin LE.

Best had a kite with quite thin LE, Nemesis, it even had dyneema fabric LE. It was a serious try but as a kite it wasn't anything so special after all, but not a failure by any means. However when heavy riders used it in higher winds it tend to buckle or even invert itself.

Light weight kiter may be unable to get enough pressure with a normal pump if kite has very thin LE.

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Re: Free kite plans on GitHub

Postby VP22 » Fri Mar 20, 2020 7:56 pm

i made a custom GO 9m² because i just keep one strut. The LE and the one strut is made with cuben fiber . the total weight: 1,55Kg. with hydrofoil is just magic because the kite flight in very light wind. thanks panthau for this works.

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Re: Free kite plans on GitHub

Postby kiteykitekite » Fri Mar 20, 2020 11:04 pm

Yes design considerations cover more than just flying. But the peak should teach that not all kites need those considerations. I am sure though that a thin LE could be quite relaunchable though, especially if you can reverse it well.

I am aware of the round LE need for AOA change, but how round? vs the disadvantage for the added weight and drag.

Yes the Nemesis was thin but not as thin as I am thinking. I would guess buckling is because it was not bridled enough or maybe the kites were not pumped enough or had leaked.

Yes for higher pressure we will need a different pump. It is quite silly there has not been an innovation in pumps. Adding a high flow battery powered fan would make the experience so much better and cost little to make. It would do most of the pumping quick and with no effort, you just use a smaller high pressure manual pump to finish.

I was thinking maybe how to come to the calculation for the thinner LE and bridle density. If we looked at the smallest tube kites like size 3-5m, what is their tube diameter and bridle spacing? I think if we replicate those numbers on a larger scale it should work. I.e. if a 3m kite has a 10cm tube and bridles space at 30cm, we replicate that on a 10 or 15m kite. say at 7m span you end up with 23 bridle attachments on the LE. Most foils are 14 to say 20 so this is not unreasonable. The drag from just having an A bridle is not much.

This also got me to thinking that big foil kites should probably have more bridles to support them and that the scaling really doesn't work well. I think as you go bigger you probably want to increase AR(already done), but also reduce airfoil thickness, increase cell count(done a bit) and bridles. I think there is non linear effects to scale in aerodynamics that support this. It's why we see such difference in relative performance from different kite sizes, with the smaller kites always performing better. It's that when you scale any design smaller it always improves. It's because the actual dimensions are smaller. But what if we reversed it and carried the actual smaller dimensions to the larger kite? What if we were to fly 2 6m kites side by side instead of just one scaled up 12m? Well two 6m kites side by side is more like one 12m with double the AR. So should we scale AR with size? It makes the designers job maybe a nightmare but I think we could write software to do it.....

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Re: Free kite plans on GitHub

Postby downunder » Sat Mar 21, 2020 3:32 am

Two of my thin LE kites, LF HiFi and FS Boost1 exploded.
And I do not even pump that hard with my 59kg.

So figure out...

The 9m area of LE comparing to 6m or less is way more suspected to buckle.

And it WILL explode on weak point where it usually buckles. Having a ticker Dacron or bladder will defeat the purpose.

So, back to square one.


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