Page 2 of 3

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Tue Sep 10, 2019 7:47 pm
by PugetSoundKiter
Rein de Vries wrote: ↑
Tue Sep 10, 2019 6:31 pm
When i pull the break lines the same effect is achieved i saw, and the kite flies better.
PL Arcs can usually fly with slack rear lines. The stiffer the spars the better, carbon rods are best, aluminum is ok, fiberglass is usually heavy, don't use bamboo (I tried this once and the spar flex alone made the kite clap). Maybe try adding attachments for the rear lines from the end of the spars further towards the leading edge, called flares: http://www.arcusers.net/mx5alan.html.

Before starting skin modifications maybe read this link for some ideas about curing the clap :clap:
http://www.arcusers.net/viewtopic.php?f=4&t=889

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Wed Sep 11, 2019 12:21 am
by foilholio

That type of tuck won't fix the issue. You need to go across the width of the cell not the cord.

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Wed Sep 11, 2019 9:37 am
by merl
foilholio wrote: ↑
Wed Sep 11, 2019 12:21 am

That type of tuck won't fix the issue. You need to go across the width of the cell not the cord.
I don't remember seeing the mod to which you are referring, but the topskin tuck as referenced definitely 100% fixed clapping issues in e.g the Guerillas in smaller sizes and was endorsed by vlieger op (the PL company). Now I think about it you used the tuck in the centre for this fix. All I am saying is that it might not be completely useless in this case.

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Wed Sep 11, 2019 10:35 am
by Rein de Vries
Hey! Great inputs, thanks! For clarity,i observed two issues with this kite. Clapping when the inflation was not fully there, but more severely, the kite flaps towards the kiter when flown with some speed. I think by wind from the other side.

Probably both issues are treated seperately. πŸ€”πŸ˜€

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Mon Sep 16, 2019 11:07 am
by Rein de Vries
So, to me, Merl's proposed solution is quite clear from the tuck illustration on the cells cord. But foilholios proposal, sounds promising as well. I dont fully understand the contrast with Merls approach. Foilholio, you tuck across the width of the cell, in the center of the cell, effectively taking away cloth from the upperskin cordlenth? In that case i understand the difference.

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Mon Sep 16, 2019 11:50 am
by merl
Foilholios proposal is new to me but addresses the front collapse problem -... (edit) is it a theoretical mod or has it been tried? The standard tuck I referred to is used to fix "clapping" as well as asymmetric flying.

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Mon Sep 16, 2019 11:42 pm
by foilholio
My mod has been used by me. I have used it to fix asymmetric flying, but it also affects clapping as you are individually altering the camber shape of cells. I learnt it from Peter Lynn, but his version is a bit different. He takes a diamond from the width of the cell. Given how small I was making my adjustments to the fabric and how I wanted to distribute them that seemed not practical nor right for some reason. I have actually used the TST as mentioned and found it not very effective, after multiple TSTs the problem was never fully or correctly fixed. I would say with ease and confidence my method would have fixed it fully on the kite I had trouble with. Knowing what I know now just looking at the TST I have reason to see it not working well. It makes changes to the width or span of the cell, so will effect the arc. The arc is made more flat which is more unstable. It does however make the the arc change more at the front, which should in theory twist the wing open more increasing the AOA at the tips. But alas in actuality I found it not very good. There is a more simple adjustment that works on the same principle and that is to stretch the fabric on the TE, it does sort of work too but damages the kite and you can rip the fabric.

As to fixing asymmetric flying with my mod of note one side of an asymmetrically flying kite will have a tendency to collapse more than the other side. If you apply my mod to the side that collapses such to the top skin to reduce camber, it will eventually exhibit less tendency to collapse and eventually the same as the other side when then the kite will fly straight. You could apply it to the side that is not collapsing as much on the bottom skin to increase camber and too make it collapse more, this would eventually achieve straight flight now with both sides collapsing more. Why do I bring this up? well for a kite like the Psycho 4 this among as well the bridles controls how much C shape the kite will go when depowered. The PA change is actually a controlled form of tip collapse! I would guess flysurfer discovered this though solving the tip collapse on the Pyscho 3 and also experimenting with ARC style kites. An Arc is highly dependent on the shape of the kite as the OP will be discovering. :-)

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Wed Sep 18, 2019 6:45 pm
by Rein de Vries
Thanks experts! With some dedicated study on what is said I think I know what to do. Keep you posted! πŸ˜€

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Mon Mar 23, 2020 8:20 am
by Rein de Vries
Hey!

After the winter period I picked up the Speed again to try and improve it using the skin tuck method. As foilholio’s approach appeared the most nuanced to me, I tried it on the outer 6 cells, by placing a tuck over the width in the center of the cells of about 0.8-2 cm. Where the 2 cm tuck is on the cell closest to the center. I tapered it off to zero towards the profile connection sew lines on the cell. At the moment everything using duct tape, just to experiment.

Actually I was positively surprised with the effect of this, in my view, rather subtle change, the handclapping is completely over! 😊

As the wind was rather gusty today, the other problem, was even more pronounced however. The arc rises quickly up in the sky but especially if there is some tension on the rear lines flaps with the nose in the wind, inverting the kite. So no solution for that issue yet.

Should I just continue with making some bigger tucks over the width into the middle of the kite for this issue? My impression is that it starts mainly in the middle of the kite.

Some words about the aerodynamics about the solution is also highly appreciated, I would really like to understand why a specific shape change could resolve it.

Curious to hear your thoughts!

Rein

Re: DIY Arc Speed 5.5 from foilmaker

Posted: Mon Mar 23, 2020 12:17 pm
by merl
Rein de Vries wrote: ↑
Mon Mar 23, 2020 8:20 am
Actually I was positively surprised with the effect of this, in my view, rather subtle change, the handclapping is completely over! 😊

As the wind was rather gusty today, the other problem, was even more pronounced however. The arc rises quickly up in the sky but especially if there is some tension on the rear lines flaps with the nose in the wind, inverting the kite. So no solution for that issue yet.
Interesting. Foilholio's suggestion was intended to cure the "other problem", but it seems it makes it worse. The two different tucks change the tension in two different directions. The classic Peter Lynn tuck increases the horizontal tension across the top skin. This can compensate for too much tension in the bottom skin which is one cause of asymmetric flying. The foilholio tuck increases the tension from leading edge to training edge, which he suggested would flatten the profile. It sounds like the simplest looking kites remain surprisingly difficult to understand.

A general question: what is the effect of the flysurfer PMS (?) adjusters? Is it s vertical tension adjuster too?

Edit: They are called Profile moment adjusters (PMA), and adjust in the same direction as foilholio's topskin mod. Perhaps adding a PMS adjuster is easier to implement too. Has anyone ever tried adding a PMA style adjustment?
Screenshot 2020-03-23 at 14.38.02.png