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First foil kite flight. Wingtips keep folding and tangling?

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

Postby Lars Madsen » Fri Jun 03, 2016 6:57 pm

kitexpert wrote:"
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.

I just got a used sonic 11 ( I have a sonic 18 from new 1 year fly perfekt) but this one fly like a hole different kite . the wing tip folding like all the time (the 18 almost never fold ind ) When I measure a and A bridle lines lokes like it about 2 cm to short, if I measure it right? So your ide with stretching A bridle line could be for me. But how exactly do you do that? Take them of an put them on something and pull? and how hart should you pull?
When I got it B was -5 and c - 10 . First time out I put b and c to zero and them to b -2 and c -4 . i am using a naish bar. The way it fly now I dont dare to jump high.
ok there is a little turbulent wind the 2 time i been out.
I just hope that the 11m could be great like the 18m.

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

Postby kitexpert » Fri Jun 03, 2016 11:56 pm

Lars Madsen wrote:
kitexpert wrote:"
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.

I just got a used sonic 11 ( I have a sonic 18 from new 1 year fly perfekt) but this one fly like a hole different kite . the wing tip folding like all the time (the 18 almost never fold ind ) When I measure a and A bridle lines lokes like it about 2 cm to short, if I measure it right? So your ide with stretching A bridle line could be for me. But how exactly do you do that? Take them of an put them on something and pull? and how hart should you pull?
When I got it B was -5 and c - 10 . First time out I put b and c to zero and them to b -2 and c -4 . i am using a naish bar. The way it fly now I dont dare to jump high.
ok there is a little turbulent wind the 2 time i been out.
I just hope that the 11m could be great like the 18m.
11m kite has shorter chord than 18m kite, this makes same bar movement to have greater AoA change in 11m kite. Smaller kite is also more sensitive to changes in bridle line lengths because they are relatively bigger for it. But of course lines are shorter in smaller kite so that balances that.

If your B and C are negative, it means greater camber which means decreased stability, -5cm and -10cm is a lot. If you want more stability B and C should be longer to decrease airfoil camber. So it is possible to alter or preset airfoil camber by adjusting mixer. However there is only one position (everything in level, if bridle is ok) which does not distort the airfoil (or does it optimally). And like I wrote it is not correct to adjust whole kite's camber if problem is only in wingtips.

I would start stretching from the AIII, then A5, A6 and if necessary every primary line in that area. It is good to check B and C too. You don't have to take them off the kite, although in FS it is quite easily done because of LCL's. Thicker lines need more pull of course. Lines have loops in each end, use some rods, weights, larks head knots etc. and measure the results. One trick is to do one side of the kite first and have a testfly to see the effect.

Sonics bridle is good work, it is clear and it has well designed cascades. Problems may occur because lines are thin. Sonic is a kite with compromises some durability and usability for high performance.

All in all, it is best to get back to original lenghts and to concentrate in problem area.

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

Postby foilholio » Sat Jun 04, 2016 3:18 am

kitexpert wrote:If your B and C are negative, it means greater camber which means decreased stability, -5cm and -10cm is a lot. If you want more stability B and C should be longer to decrease airfoil camber.
WTF? Shorter B and C equals negative or reduced camber so more stable, not longer. You wonder why I disagree with you sometimes!

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

Postby foilholio » Sat Jun 04, 2016 3:32 am

Lars Madsen wrote: I just got a used sonic 11 ( I have a sonic 18 from new 1 year fly perfekt) but this one fly like a hole different kite . the wing tip folding like all the time (the 18 almost never fold ind ) When I measure a and A bridle lines lokes like it about 2 cm to short, if I measure it right? So your ide with stretching A bridle line could be for me. But how exactly do you do that? Take them of an put them on something and pull? and how hart should you pull?
When I got it B was -5 and c - 10 . First time out I put b and c to zero and them to b -2 and c -4 . i am using a naish bar. The way it fly now I dont dare to jump high.
ok there is a little turbulent wind the 2 time i been out.
I just hope that the 11m could be great like the 18m.
The kite could be sewn up incorrectly and is a dud someone got rid of. If the mixer was so radically changed like that with B -5 and C -10 sounds like it had some issues. Making them longer by changing B to -2 and C to -4 will make the kite less stable than -5 and -10.

To stretch the bridles you attach the mixer/line ends to something and just pull on them. To get an even pull bridle to bridle and most IMPORTANT to NOT BREAK your bridles use a weight connected to a rope run through a pulley connected to your mixer/line connections. I would try with 15 to 20KG for the weight, the sonic has lighter bridles than other kites so you may break a bridle even with that weight. You can pull from the kite end in such a way that the LCL can help protect the bridles. You don't need to disconnect anything. It won't be possible to restretch to original lengths but you can even or level the whole kite. Stretching A alone may make your problem worse as Z is the main bridle that shrinks and a short Z is the same as a long B and C, making the kite unstable.

Is there any asymmetry in the kites behavior? Like collapsing more to one side or flying to one side? I would measure the pulley lines as well.

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

Postby kitexpert » Sat Jun 04, 2016 11:30 am

foilholio wrote:
kitexpert wrote:If your B and C are negative, it means greater camber which means decreased stability, -5cm and -10cm is a lot. If you want more stability B and C should be longer to decrease airfoil camber.
WTF? Shorter B and C equals negative or reduced camber so more stable, not longer. You wonder why I disagree with you sometimes!
Those huge corrections and still unstable kite lead me thinking it wrong.

Of course if you make B-C shorter, camber decreases, if longer it increases.

"Stretching A alone may make your problem worse as Z is the main bridle that shrinks and a short Z is the same as a long B and C, making the kite unstable." -foilholio

Stretching A at the wingtip problem area makes it more stable. No matter foilholio says. If Z is too tight kite may backstall and it behaves more twitchy, although it turns better. Z tightness is a bit matter of taste and it should be adjusted last. I used to make testflys even without brakes at all, decent foilkite flys and turns without them.

Adjusting Z is very easy (or at least it should be), it is just a straight line which is pulled 1:1.

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

Postby foilholio » Sat Jun 04, 2016 11:44 am

Every thing works in ratio, a change at Z is the same as changing B 1/4 and C 1/2. Except you can change the final depower point with the B length. It is possible to change the ratio to what ever and maintain the same depower point or do the opposite changing the depower point while maintaining the ratio. Adjusting Z alone is one of the biggest influences on stability and lift. Shortening it actually reduces stall.
kitexpert wrote: If Z is too tight kite may backstall
Again how is it not a surprise when you talk rubbish I would disagree. We are not talking about fixed bridle kites here either.


Adjusting A is the same as changing B 3/4 and C 1/2. Except it changes the depower point by 1 as well. Lengthening A could make it more stable but changes like that can be weird.


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