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First foil kite flight. Wingtips keep folding and tangling?

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kitexpert
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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby kitexpert » Mon May 16, 2016 5:31 pm

If problem is in the tips, the cure should be for the tips. Wingtip folding results from three main reasons:

1) Kite is underinflated. This happens if kite is not airtight, like many Speed3's nowadays. Air intakes are far away to pressurize leaking wingtip cells.
2) AoA of the wingtips is too low
3) Airfoil of the wingtips is too cambered, not stable enough

Kiter can adjust wingtips to a higher AoA (and/or lower the camber). Because R1 is a new kite leaking is not the culprit. For tangling bridle lenghts may not be optimal, but for bridles there are more important design requirements than to avoid tangling.

In practice B-linerow should be shortened perhaps 2cm and C 4cm in the problem area of the wing. Or just shorten B, it is the classical fix. It is wise to make adjustments for one side at the time, so effect is well observable and original setup can be restored if needed.

Lowering the camber of the whole kite is worse for the performance than to adjust just wingtips.

-----

"....to measure a few bridles and use that to calculate adjustments at the mixer to compensate for the bridle changes on the kite. It should make restretching largely unnecessary." -foilholio

This helps but is a kind of shortcut. Bridle line lenghts vary a lot spanwise (and so does the shrink) and they also support kite canopy curve, the arc shape of the kite. In P4 bridle line rows even have a function to change PA of the kite. And if kite has different airfoils and different AoA in different part of the wing bridle line lenghts should be correct for these too.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby plummet » Mon May 16, 2016 11:31 pm

norcom wrote:
plummet wrote:Is this tip tucking while launching?

Or have you fully inflated the kite have it in the air and get tip pucking when flying?
Both? While launching I've had the tip catch and not recover and I've had it launched, in the air, moving it around the window. It felt powered and looked inflated all through. Then while moving it around in the window one of the tips would tuck and catch on some bridle lines.

I think the wind was just too light and I did something wrong. I was worried that it wouldn't stay in the air so I kept trying to move it through the window. Maybe it needed more pressure built up before it could go?
Before you adjust anything like what kite expert is saying. Try this.

When inflating bar in hard. Keep the kite stalled deep in the window until its fully inflated. In ultralight wind it may not pre-inlfate buy its self. you may have to run backwards while feathering the bar to keep the kite stalled and in the powerzone.

Once inflated and in the air keep the kite moving with emphasis on keeping the line tension and kite speed. When line tension is lost the chance of tip tuck is high. Keep the bar out enough to get kite speed but not enough to loose line tension.
Keep the kite away from the edge of the window. Kites don't tip tuck powered up in the powerzone.

If none of that works then look for problems with the bridles. Is it tip tucking only on one side? or exactly the same on both? If its one side there there is a chance there is a small bridle snag causing the issue. There are real easy to get and hard to see with those teny tiny bridle lines.

Then if none of that works, perhaps think about making adjustments to the actual bridles. I think this would be a last ditch effort.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby Kamikuza » Tue May 17, 2016 1:09 am

foilholio wrote:This is why I think side of the window launches are just a waste of time, you need to spend heaps of time preinflating and the kite often ends up downwind anyway. I think inflatable riders cant understand how foils can be "hot" launched, it's because they just have so very little pull until inflated or while backstalled and they don't spike with power like an inflatable.
You mean he race foils or any? I side launch all the time and perhaps half the time don't pre inflate at all. The other half, I'm too impatient to do a proper job of it. No problems so far.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby foilholio » Tue May 17, 2016 1:39 am

Yes you can not preinflate but you need to start upwind then move downwind. The whole thing is complicated and does not give as much control as straight down wind. Yes you can have no problems, but I am sure you give yourself the room to the side and downwind. Straight down wind you don't really need to worry about either side, if you are good at it. I have launched many times between a thick of inflatables with many on each side of me. Mainly because they give me the shits and do things, probably from a lack of knowledge, like setup right next to my lines or run their lines side ways so I am forced to setup over the top of them. Freaks them out a bit when I launch :-) though some do start to get used to it. I like to throw in some helicopter loops just to liven it up for everyone now :-) looks a bit like a launch gone into a death loop lol.



kitexpert wrote:but for bridles there are more important design requirements than to avoid tangling.
Depends how you ride, if you ride freestyle or wakestyle you drop the kite a lot and bridles cause large headaches , like death loops. This is why bridleless C kites are preferred for this style of riding. They will talk about slack but that is largely rubbish as other kites can "slack" as well. For me riding waves I somewhat regularly collapse or drop the kite, if something tangles its extremely annoying and could possible get the kite damaged. This is why I don't like anything on foils that causes tangles, like heavy pullies or large knots on pigtails. Even in riding where the kites should really not be dropped like in racing, inexperienced flyers plus very high performance kites with these things will create tangles, especially in gusty lully conditions.
kitexpert wrote: In practice B-linerow should be shortened perhaps 2cm and C 4cm in the problem area of the wing.
Ozone has no adjustments for B or C only Z. Which is fine because lengthening Z 8cm is the same for the profile as shortening B 2cm and C 4cm. Shortening B though does move the tow point back when depowered making it more stable depowered but have less depower. It is surprising what effect just the profile alone has on a kites stability and not the tow point. I think the big discover in parafoils is by sewing more reflex in, the tow points have been able to be moved much further forward while still being stable and yet have less pull/better depower. Tension on B rather than viewed as just changing AoA could be looked at as creating a kink in the airfoil at that point, the front of which generates an upward moment and rear a downward moment. Both would combine to make the wing want to increase AoA but not in a classical stiff wing sense.
kitexpert wrote: It is wise to make adjustments for one side at the time, so effect is well observable and original setup can be restored if needed.
This is good advice, I have used it many times testing things.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby davesails7 » Tue May 17, 2016 9:36 pm

Th wingtips were folding on my 15m sonic during use. I checked my mixer. B, C and Z were about 2 cm shorter than A. I set them all back to even and it made it worse!

I messed around with the settings, and found that shortening B made things a bit better.

Then found that adding a 1.5 cm pigtail to A solved the entire tip collapse problem.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby foilholio » Wed May 18, 2016 2:17 am

That is weird I wonder how you were doing the mixer test as it normally aligns A and Z to start the test, so a change in the length of Z should not be noticed. Lengthening A 1.5cm would be the same as shortening Z 1.5cm, and then doing a mixer test and shortening B 1.125cm and C 0.75cm. Sounds much simple to just lengthen A lol. Of note there is no way to achieve what you did by adjusting B and C alone, if you adjusted Z as well you could have like I explained. I think foil kites need 3 adjustments, B and C alone is not sufficient. Z is great because the low pressure on it means knots arn't too tight and it alone can achieve things in a much simpler fashion than B and C. Adjusting Z for 4 is the same as adjusting both C for 2 and B for 1, which is the advice flysurfer gives when ever adjusting the mixer, always C for 2 and B for 1.

I also find it interesting you shortened B more over C to find your solution. I am still trying to understand the B and C relationship. I have noted so far B can increase stability but not power as much as C does, C increases stability but also power a lot. When I was testing my various mixers I had no luck maintaining stability in the kite. Though in one of my mixers where the tension on C was double B I never tried it in reverse. Maybe with double the tension on B vs C the stability could be maintained and my goal of a shorter bar throw achieved. I will have to test. Thanks. I suppose thinking about it a bit the order of highest tension to lowest the bridles experience goes ABCZ , so from that view B should have more tension/i.e. shorter vs C.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby kitexpert » Wed May 18, 2016 7:35 pm

"I messed around with the settings, and found that shortening B made things a bit better.
Then found that adding a 1.5 cm pigtail to A solved the entire tip collapse problem." -davesails7

About same effect can be achieved in different ways. Lenghtening A equals shortening other line rows. It is a bit different than shortening just B, but no doubt it works. It is still best to do this adjustment to the problem area only, adjusting mixer is for the entire wing.

One easy method could be stretching some (or all) A bridle line in the problem area or at least to check that they have not shrinked. Wingtips are less loaded than center of the kite so that may be the case. On the other hand, short wingtip area chord gets more AoA change from B to Z, so perhaps they stretch (or shrink less than A), resulting folding wingtips.

I would first stretch tertiary, then secondary and if needed primary bridle lines. I think couple of cm's more lenght to A would result quite surely.

"Ozone has no adjustments for B or C only Z. Which is fine because lengthening Z 8cm is the same for the profile as shortening B 2cm and C 4cm." -foilholio

Yes I know Ozone does not have adjustments. It is stupid, but you can do it one way or the other. Lenghtening Z especially near wingtips is not a good idea because it makes turning worse.

Line lenghts affect spanwise too: if you lenghten Z at the wingtips 8cm it is that much longer in relation to center of the kite. For turning speed wingtip brakes are essential, they must not be too loose.

Locational adjustments must be made above the speedsystem, but preferable as far from the kite as possible (in secondary or tertiary bridles). Adjusting single primary bridle lines is usually unnecessary and more laborous. FS's LCL lines are handy and can be modified if this is however done. Every foilkite should have them.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby foilholio » Thu May 19, 2016 3:00 am

Ozone has an adjustment for Z. I meant adjust Z at the mixer with this adjustment. 8cm was just an example to show how B and C work with Z and is actually what you suggested to change the kite by, but with B and C to do it. I previously said loosen Z 2cm at a time.

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby norcom » Sun May 29, 2016 3:41 am

I was finally able to get the R1 17m into the air today and got a little over an hour of riding. :jump: The wind wasn't as light as I would have liked it to be. It was between 10-16mph. I could have easily been on a tube but when I got there it was averaging 8mph. Took me an hour to get it in the air and only when the wind finally picked up. I don't know how anyone launches these things in anything under 8mph.

Turns out that what I needed to do when the wingtips were folding was to pull on the break strap. It would put the kite deep and low into the window and open it up. Had to do it a few times. I thought the kite was going to fold in half but it recovered! Doing that in this much wind felt very sketch. The pull was massive while filling the kite by pulling the brake strap.

No issues with the bridle or anything else. Kite flies very perfectly and with plenty of power. I was on my Monster Door. Felt overpowered but the upwind and downwind was excellent. Kite definitely has some speed. Even got some jumps in.

Now I had a new problem, landing. With this much wind it turned out to be an issue. I pulled the brake strap, the kite came down pretty hard and sat on the beach. I kept holding the brake strap and the kite started to reverse relaunch, so I just punched out. It did some spins and settled down. There's not much clean beach to launch/land. When landing I was waist deep in the water while the kite was on land. Really wish there was some way to self land it on the side of the window with a sandbag/anchor. Maybe I'll try to put it on the side of the window next time and punch out, instead of the brake strap.

Edit:-------
Looking at this video https://www.youtube.com/watch?v=ssU5RkUHzUc
When the guy pulls the steering lines the kite comes down on the trailing edge. When I pulled my brake strap, the kite came down on the leading edge. I think it did some kind of a turn half way? When pulling the brake strap, should the kite come down on the trailing edge?

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Re: First foil kite flight. Wingtips keep folding and tangling?

Postby foilholio » Sun May 29, 2016 4:35 am

Yes it should come down on the trailing edge. Some times if you pull too much of the rear lines the kite will invert and reverse launch. Is that what happened?

I spoke about making something to aid in landing at the side of the window here viewtopic.php?f=197&t=2392406&p=929441.
foilholio wrote: On a side note it would be possible to design a device to snag the tip bridles and flag the kite out. Could be a hook on a stake to hold it upright, with a loop and leash that you tether to your kitebag or other bag full of sand. Fly the tip into it, you'll know when it catches :-), and then quickly run at the kite to flag it. One of the brands could take the idea and make it really quite cool, like a tent stick style construction so it packs very compact. Maybe with a large detachable plastic hook so it doesn't damage the bridles. Oh and now the really cool idea, no stake, no sticks, a self flying mini pilot style kite with a hook that you fly directly off the sandbag/kitebag/sand anchor( flat bit of fabric buried). It could be really tiny and so cute lol. Call it a "parking kite" instead of pilot. I want to make it :-) ROFL
Hopefully you can find your answer to land the kite in that thread. Oh and you can buy pilot style parafoils cheap off ebay just search for "parafoil". Maybe it will work. Or you could add a fifth line if you want peace of mind. Either make it or get one from a flysurfer speed or sonic , if they are available. I am sure ozone would make it for you as well.

Launching in light winds you need to downwind launch and preinflate on the ground. Stand behind the kite and hold the middle vent up open to the wind. You need enough air so the vents and kite can catch enough wind so it will continue to inflate when at the bar. Tugging on the front lines/leader can help.

You can avoid most launch problems especially in higher wind by inflating the kite while it's on or near the ground.


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