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Foil Kite folding in half when going upwind!?

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foilholio
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Re: Foil Kite folding in half when going upwind!?

Postby foilholio » Mon Jul 16, 2018 1:09 am

Well the kite is not folding in half is it? So it appears fixed in that regard. There appears a tip issue with associated bridle issue there. I think he hasn't lengthen Z to have the same effect as he had in the picture, where B appears 1.5cm shorter. Lengthening Z more may improve the tip but it is better to fix the tip bridle if it has LCLs so it can be done easy. He could stretch the bridle there at the LE, but it is hard to tell with out a line plan exactly what needs doing. Looking at the second video again though it is definitely a B bridle as it reacts to bar movement. Makes sense as this is what kite designers tend to do, move B and C forward on the cord towards the tip. In which case shortening B is not a good solution, shorten C would help but it will just throw the rest of the bridle out. The tip bridles need to be fixed.

As to regards to B, this will need to be lengthened more with C and Z in ratio to restore full depower. You need will need a line plan to calculate the amount or generally it is till B goes slightly slack (bowed) when bar lines are at max depower (rear lines well bowed).

As to kitexpert, he is a bit of a strange one. All evidence points to him being a Tube kite designer, you just need to talk to some, read their posts or see that new BS article. He doesn't seem to actually use foil kites much. Which is more strange because he gives lots of advice on them, and incorrect like above. Adjusting Z has the biggest effect on foil kites than any other bridle. It is commonly known and understood. Flysurfer has perhaps muddied the water by going about it in a strange way of adjusting both BandC to get much the same effect.

kitexpert
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Re: Foil Kite folding in half when going upwind!?

Postby kitexpert » Mon Jul 16, 2018 7:30 pm

foilholio wrote:
Mon Jul 16, 2018 1:09 am

As to kitexpert, he is a bit of a strange one. All evidence points to him being a Tube kite designer, you just need to talk to some, read their posts or see that new BS article. He doesn't seem to actually use foil kites much. Which is more strange because he gives lots of advice on them, and incorrect like above.
Nonsense, you foilholio just don't know enough. Even worse, you think you know even you don't.
foilholio wrote:
Mon Jul 16, 2018 1:09 am
Adjusting Z has the biggest effect on foil kites than any other bridle. It is commonly known and understood. Flysurfer has perhaps muddied the water by going about it in a strange way of adjusting both BandC to get much the same effect.
Nonsense. Lengthening Z has zero effect on anything when it already slacks, and that is when most unstability issues exist. Very rarely kite collapses when AoA is high - if it does it is shitty kite or badly out of tune. Of course when sheeted in loose brakes make kite to go lower camber, but for what the f*** it is needed any more? It is just harmful, it makes absolutely no sense!

You foilholio don't understand different kite/mixer positions during the depower range, how line tensions and CoL are in different AoA's and how they should be for kite to behave correctly and to be stable enough.

I repeat: adjusting A-B (C) ratio is completely different compared to your suggestion for "same effect" because Z is almost or completely slack when this adjustment is needed and done. Do you understand know?

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Re: Foil Kite folding in half when going upwind!?

Postby PullStrings » Mon Jul 16, 2018 10:20 pm

I sense so much nonsense from "A-B (C)Zoolio"
He is understandibly in his own mind a foilmixerexpert

foilholio
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Re: Foil Kite folding in half when going upwind!?

Postby foilholio » Tue Jul 17, 2018 1:00 am

No kitenotanexpert, unlike you I fly and use foil kites all the time, and understand how changes to them affect actual use, not just some theoretical model you most likely don't understand correctly. But please go on exposing your shit, someone else will come along eventually to have a laugh as well.


Pullstrings doesn't even use foil kites and just trolls. But hey keep posting more TP, it is actually funny sometimes. A star for effort too. Supa :-) effort!

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Re: Foil Kite folding in half when going upwind!?

Postby socommk23 » Fri Aug 10, 2018 4:43 pm

A lines need lengthening or b and c shortening. An increase in camber can introduce a frontal collapse but lengthening the z lines will not change the aoa of the front of the aerofoil therefore will not alter it's collapsing. Imo

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Re: Foil Kite folding in half when going upwind!?

Postby foilholio » Sat Aug 11, 2018 12:48 am

The AB relationship is primarily changed with the Bar position or trim. When B engages it isn't so much a change to AoA, though it does change over all and for the frontal area as you say but this would be considered a reduction in camber as well. When you slack Z you are allowing B ( and C) to engage more. It really does have an effect on collapsing.

You can limit B, but most foils are not designed like this at the windows edge. Why would you want to permanently limit it when you can do that with the bar? When conditions allow you now have less depower, both your low end and high end will suffer. The kite will stall easier and have a higher minimum pull. You have lost range with no need to.

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Re: Foil Kite folding in half when going upwind!?

Postby jakemoore » Sat Aug 11, 2018 1:26 pm

kitexpert wrote: Nonsense, you foilholio just don't know enough. Even worse, you think you know even you don't.

You foilholio don't understand different kite/mixer positions during the depower range, how line tensions and CoL are in different AoA's and how they should be for kite to behave correctly and to be stable enough.
Certainly a CAD would help! How else are we hoing to know if the kite is stable or not?

OP: Is impossible to tell from YouTube videos if the kite is flying well. Fly it in light wind. Does it sit nicely at the edge of the window? Stable? Does it make a nice pull when you pull the bar in? Turn the way you like? Does it backstall too much?

It won’t hurt to move some lines around and find what it does as long as you know how to get back to a starting point e.g. with a mixer test. It helps to understand that lines shrink. Front lines on the bar shrink less than the rear because they carry more tension. For the same reason line shrink affects Z > C > B > A above the mixer all the way up to the kite. Pully lines can also shrink a lot because they are subject to abrasion - especially if prestretch lines are used. Mixer test with even knots accounts for pulley line changes more than changes above the mixer.

On my older foil kites, I like to put Z pig tails between each Z-main and the secondary Z risers. That way I can lengthen Z at each section of the kite. I like to go just enough to prevent most frontstalls, but not too much to make the kite dull.

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Re: Foil Kite folding in half when going upwind!?

Postby davesails7 » Sat Aug 11, 2018 1:39 pm

I gave up trying to read through the back and forth, but would add this because I dont think it was said:

This is a known issue with the LF elite. Not sure if it can be fixed by adjusting bridles.

I heard it was because the air intakes are in the wrong spot. I've seen it on several different LF elites of different sizes, but I think it was worst on the 15m. Rider goes upwind. No air is getting in because the air intakes are in a low pressure area. Eventually the kite folds in half/front-stalls and it's in the water.

LF elite was a disaster. I first saw this happen on an early prototype. Then somehow it was never fixed and went to production like that!

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Re: Foil Kite folding in half when going upwind!?

Postby foilholio » Sat Aug 11, 2018 3:31 pm

Me and the expert do make a mess in threads.

Nash556 didn't get back here again I assume he has no more problem.

Funny though Nash556 got talked out of a Pansh because someone suggested he might have to adjust their bridles. Adjusting bridles is a fact of life with foils, all brands need it at some point.

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Re: Foil Kite folding in half when going upwind!?

Postby jakemoore » Sat Aug 11, 2018 8:19 pm

foilholio wrote:
Sat Aug 11, 2018 3:31 pm
Funny though Nash556 got talked out of a Pansh because someone suggested he might have to adjust their bridles. Adjusting bridles is a fact of life with foils, all brands need it at some point.
You can’t polish a turd.


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