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the "Malabar" mixer test for large foilkites in light wind

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Regis-de-giens
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the "Malabar" mixer test for large foilkites in light wind

Postby Regis-de-giens » Sun Jan 17, 2016 10:46 am

In order to increase depower trim length and increase rotating speed of foilkites, I have "developped" a new mounting of mixer test (speed system), that we can discuss here, together with its impact on control and actual depower even with line extensions.
Here below is the discussion we started initially on the subject of the pansh a15-a18.
Last edited by Regis-de-giens on Sun Jan 17, 2016 2:57 pm, edited 1 time in total.

Regis-de-giens
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Re: the "Malabar" mixer test for large foilkites in light wi

Postby Regis-de-giens » Sun Jan 17, 2016 10:48 am

here is the history of discussions :
Regis-de-giens wrote:
foilholio wrote:turning is quite a bit slower, but the upwind is actually quite good now and the bar even lighter, as all would be expected. The difficulty I have with it riding upwind is the bar is so light I usually use it to feel stall point because I have a back stall throw. Bit hard to do but just need to practice more I guess. I am quite keen to adjust or modify something to increase effective throw and/or bar pressure.
Hi Foilholio,
Very interesting Review's ... thanks.

I can suggest you an idea I had to improve both the bar pressure, trim efficiency and turning efficiency, by changing the Mixer mounting. I call it “Malabar”, and it is a kind of "2:1 turbo" control bar, but now relocated on the kite bridles and not on the bar ; you can find some explanations here if you can read french:
http://www.tubelesskite.net/t6811-barre ... abar#82520

In one word, the idea is to change the driving of C bridles as shown in the attached picture that I issued in English for you:
- revert the its spare lines of C pulley
- connect this SPL to A on one side and Z on the other side
- connect rear line from the bar to both C pulley and C bridles (with a kind of bridge to cross C pulley).

That way, C will be driven in 1:1, B in 1:2 (instead of 1:4), and Z will be driven in 2:1 (instead of 1:1). Consequence is:
- Twice bar pressure
- better efficiency of the trim length (as if it was twice longueur)
- Better turning radius due to increased left/right length differential (as if control bar was twice larger)
- rear lines see twice the standard tension (*)

(*) this is the main difference with a “turbo control bars” (mounted in 1:2 on the rear lines, that I used two years on my former Aurora 22m and it actually improved turning speed and depower); to me , this higher line tension becomes useful to increase depower in light wind especially with if you add line extensions).

Unfortunately due to lack of time, I was not able to test my “Malabar” in real ride situation on water, (and nobody from my knowledge ever tested it); I just recently tried it on land on a very large custom-made single skin I am setting-up currently. It seems to work fine. The main potential concern that I was not able to check yet is the ability to still reverse relaunch with this mounting in light winds, but if you are able to validate this point (on land first...), it may suit you !

Feel free to ask for details if you cannot read French.

Regis
kitexpert wrote:Well done, Regis-de-giens for your invention "Malabar" :thumb:

It looks simple and effient way to adjust AoA more than usual and it is obviously better system than so called "pulley bar", which can achieve same results with normal speedsystem.

Of course doubling pulling ratios is quite extreme. For big kites it seems reasonable, they may very well have double chord lenght. So, for same AoA change double bar movement or double pulling ratios are needed.

Bar pressure is the thing which worries me the most, doubling it is a lot.

Your good drawings are self-explanatory. Thanks.
kitexpert wrote:"obviously better system than so called "pulley bar", which can achieve same results with normal speedsystem." -kitexpert

Like you already explained:

"...it is a kind of "2:1 turbo" control bar, but now relocated on the kite bridles and not on the bar..." -Regis

"- rear lines see twice the standard tension (*) ... this higher line tension becomes useful to increase depower in light wind especially with if you add line extensions)."

Is there something wrong? I do not see how depower in light wind could be increased, and why should we do so?
foilholio wrote:Great system, I thought funalex came up with it? It is certainly more efficient than adding an extra pulley at the bar to just rearrange existing pulleys to have the same effect.

It would allow more depower because the bar throw and maybe total trim would be the limiting factor.
Last edited by Regis-de-giens on Sun Jan 17, 2016 11:40 am, edited 2 times in total.

Regis-de-giens
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Re: the "Malabar" mixer test for large foilkites in light wi

Postby Regis-de-giens » Sun Jan 17, 2016 10:49 am

pulley bar is indeed the same as turbo bar, sorry for the french name.
foilholio :
funalex had quite same idea, however he connected the rear lines to another briddle, which unfortunatelly was not keeping the profil stable : when he pulled the bar, the canopy getting significantly flatter (dont remember exactly but say 5cm on the B briddle), and reversly more curved when depowering which does not go in good direction : -(. i think that is why he was not appreciating its modif on top on the increased bar pressure on its 12m (as said kite-expert, it can be acceptable on a light wind large kite but painfull and useless on smaller kites).
kitexpert wrote: "- rear lines see twice the standard tension (*) ... this higher line tension becomes useful to increase depower in light wind especially with if you add line extensions)."

Is there something wrong? I do not see how depower in light wind could be increased, and why should we do so?
It is something I strongly belive in, but no general consensus. As a lot of kiters were complying about loss of high end when adding line extensions, i tried to understand who"was true" between people thinking it was due to added draft of the line in the air or not. Finally i think that everybody is true, in a sense...

Indeed to me the drag in the air will curve the lines. This curve depends on line length but also line tension. The more tension, the less curvature. The more line length, the more curvature. So, rear lines being less tensioned on a foilkite (say 20 % rear lines and 80 % front line), then the curvature is more important on rear lines as you certainly have noticed when pulling the bar. Now when you add 10m extensions lines, you actually add say 9,99m straight distance on front lines but only about 9,8 or 9,9 m straight distance on rear lines, which is equivalent as pulling more the bar = less depower (i made an evaluation of this value on tlk, based on chain curvature equation, i can recover it if you want). And even if you trim a bit to compensate (well known tip of riders in light wind, especially with extensions) you still keep a minimal rear line tension due to the action of drag on the curved line, therefore more power.

In another words, the more you push the bar, the more a growing part on the released length of rear line is "consumed" by curvature. And this phenomena is reduced with a higher rear line tension (which will limit curvature).

Pulley bar double the bar pressure but not line tension, while Malabar MT also double the rear line tension, so it limits the loss in control and depower. Another interest is that you can keep using a standard control bar, and by the way avoid the "mess" of a puley bar above the trim. last advantage, you save one pulley and its corresponding friction in your muscles ...
Last edited by Regis-de-giens on Sun Jan 17, 2016 10:58 am, edited 1 time in total.

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Re: the "Malabar" mixer test for large foilkites in light wi

Postby kitexpert » Sun Jan 17, 2016 8:20 pm

"The more tension, the less curvature." -Regis

Yes, but more (backline) tension, bigger AoA -> less depower. I don't know if there is any difference for depowering whether kite is pulled by line drag or by bar movement. If biggest depower is wanted backlines must be quite slack anyway. Shorter and thinner lines allow some more depower than long and thick ones.

"...while Malabar MT also double the rear line tension..." -Regis

It depends. Fully depowered there should not be any difference. In relation to bar movement double line tension (bar pressure) (for double effect in kite AoA change) is of course true. When pulling kite to bigger AoA's than with normal system allows, bar pressure may increase drastically, because it does not increase linearly even with normal systems. Backstall of the kite may become limiting factor here.

For the biggest of foilkites Malabar seems interesting. For example, if used in Speed21m kite same sheeting range allows more change in AoA than normal speedsystem in Speed6m kite. Malabar system does not change how camber increases when AoA increases.

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Re: the "Malabar" mixer test for large foilkites in light wi

Postby foilholio » Mon Jan 18, 2016 12:47 am

It is quite simple. It rearranges the pulleys to double all the ratios. End result half the bar throw and double the pressure. Ingeniously simple when you think about it. Applied to kites like the A15 it could be very good. I am now imagining if a kite is designed more to use this? I.e. move BCZ all further back. I feel you could then get more camber change like the diablo line. Reasoning for it is that the forward positions of BC on most kites seems to allow them to distort too soon before Z is pulled enough with a standard mixer.

I am keen to try it. Will let you know after I have.

Regis-de-giens
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Re: the "Malabar" mixer test for large foilkites in light wi

Postby Regis-de-giens » Mon Jan 18, 2016 10:33 am

@foilholio: great you want to test it ! When I will be skilled enough on foilboard, I will test it on my 15m2 speed2 SA on water.

Indeed diablo principle is ingenious. FYI I also pushed this kind of principle up to its "extrem" with my 19m2 single skin (originally a speed2 19m2) : in addition to Malabar, I have removed B pulley of the kite and connected B bridles knot to A bridles knot. The expected consequence is to increase camber when I am powering the kite and vice-versa (on top of saving the weight of 2*2 pulleys and 2*2m of spare line) and always keep a minimum of stability when depowering. It might be a bit exagerated (relativelly to the initial camber, B will shorten approx 7 cm when depowering which may impact kite performance), but I'll see.
kitexpert wrote:Yes, but more (backline) tension, bigger AoA -> less depower.
Not applicable for Malabar ... rear line tension is doubled but each tension on each bridle (A, B,C, Z) is similar, hence same AoA.
kitexpert wrote:I don't know if there is any difference for depowering whether kite is pulled by line drag or by bar movement.
It is a combination of these two factors: you always have a bit of bar movement consumed by curvature as well as always a residual tension on the rear line due to wind drag. In lower winds, the more you push the bar (i.e. try to reduce AoA) the more curvature becomes dominant on the position of the bar imposed by the rider.

In low wind, when depowering the kite, you visually see the curvature (with a sing value beyond 1 meter horizontal deflection in my experience); and you feel that when pulling the bar you have a kind of increased "elasticity in the bar"; what happened is that that part of your bar pull stroke will be unfortunately used to decrease the curvature and not drive the kite ...(hence part of the stroke is "lost"). At normal wind and speed (say beyond 8 knots) curvature visually seems to become negligible.
kitexpert wrote:If biggest depower is wanted backlines must be quite slack anyway. Shorter and thinner lines allow some more depower than long and thick ones.

We are in line on this (and I even have installed thinner rear lines on my 19m2 for that reason): Malabar or not, lines will be more slack when depowered.

However, at same depower, between standard and Malabar, you will catch more tension transiting in rear lines with Malabar (it is just a transit, no impact on briddle tensions), hence lower AoA because less curvature (i.e. more representative of your command from the bar, which is great).
kitexpert wrote: "...while Malabar MT also double the rear line tension..." -Regis

It depends. Fully depowered there should not be any difference.
It will still and always be twice tension in rear lines (and bit less in front lines :) ) . Twice of a lower value I agree, but still twice. I have not experienced the actual impact during a ride, so it is theory for now... up to foilholio next test :naughty:
kitexpert wrote:When pulling kite to bigger AoA's than with normal system allows, bar pressure may increase drastically, because it does not increase linearly even with normal systems. Backstall of the kite may become limiting factor here.
The initial application is to increase depower (allow a smaller AoA without using the trim strap or clamcleat) rather than increase power (aim is to keep same maximum AoA than with standard bar).

However you can play with it by extensing a bit the front lines and see if a little "over-sheeting-in" with even higher AoA can be useful (depends n kite design, but for jumps needs with skilled riders for exemple or little backstall abilities with can be useful in light wind when controlled. Keep in mind that your strap-trim is still available (and also doubled) to try all those settings and find the one adapted to you and your kite. Depending on kite design, it may require a bit of additional skills if you play with that, since you go beyond kite original AoA variations.

Regarding bar pressure, I don't like bar pressure generally, and I often changed my tubekite models for that specific reason. But I actually used a pulley bar on my previous Aurora 22m during 1,5 year, pressure was significantly increased but I was still able to ride several hours with my little-little muscles (60 kg). I would say it becomes equivalent to a big tubekite with same wind but depends on foilkite design.
kitexpert wrote: Backstall of the kite may become limiting factor here.
as explained above, the malabar is mainly to decrease AoA, not increase it. But if the rider also wnt to increase AoA capacitiers, that is an option, and then it could indeed induce backstall if not properly driven. I would just add that in very light wind (say below 7 knots), backstall is frequent even with standard bar if you pull too much on the bar.
kitexpert wrote:For the biggest of foilkites Malabar seems interesting. For example, if used in Speed21m kite same sheeting range allows more change in AoA than normal speedsystem in Speed6m kite. Malabar system does not change how camber increases when AoA increases.
exactly, fully in line. For example on a 6m2, if the stroke of your arm gives 15 degree variation of AoA, then for a 21m2 kite, you can only command 8 degree Ao0A variation :cry: same

PS: I copy again the Malabar sketch as it disapeared from the topic transfer
Attachments
Malabar english.jpg

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Re: the "Malabar" mixer test for large foilkites in light wi

Postby Hardwater Kiter » Mon Jan 18, 2016 12:19 pm

I would love to see a video of the mixer being actuated up close. The diagram is good as are. The descriptions but real images in action really help make things clear to those of us not really skilled in this voodoo. :D

Regis-de-giens
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Re: the "Malabar" mixer test for large foilkites in light wi

Postby Regis-de-giens » Mon Jan 18, 2016 2:47 pm

I have this but you will be disapointed :oops:
- it is not a video
- the mixer is simplified since I connected A and B together
- but a least you seen how I connected C pulley and bridle ...

I made a test today at noon, but this damned single skin is too far from being set-up (will it be one day ?) to conclude firmly on Malabar. I can just tell you that with this arrangement I was able to make it turn quicker and do not needed to use trim strap from frontstall to backstall ...
Attachments
20151005_131353.jpg
Malabar layout
20151005_131419-1.jpg
my method to mount C bridle "bridged" over the pulley
20151005_131405-1.jpg
zoom on C bridle arrangement once tensioned
20151005_131353-1.jpg
another layout ( sorry for the bad color of the ground)

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Re: the "Malabar" mixer test for large foilkites in light wi

Postby Hardwater Kiter » Mon Jan 18, 2016 6:15 pm

Thank you that helps quite a bit actually.
:D

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Re: the "Malabar" mixer test for large foilkites in light wi

Postby kitexpert » Mon Jan 18, 2016 6:17 pm

"It will still and always be twice tension in rear lines (and bit less in front lines :) ) . Twice of a lower value I agree, but still twice."..."However, at same depower, between standard and Malabar, you will catch more tension transiting in rear lines with Malabar..." -Regis

Twice the zero is still zero. When kite is fully depowered, backlines slack. Then speedsystem is irrelevant. In principle bridle rows B, C and brakes could even be removed and nothing would change (except a bit smaller drag).

"Not applicable for Malabar ... rear line tension is doubled but each tension on each bridle (A, B,C, Z) is similar, hence same AoA." -Regis

Yes of course, W=Fs. If same work (changing kite AoA) is done by half bar movement, used force must be double.

"...hence lower AoA because less curvature..." -Regis

Line drag is always there. It may look more severe with normal speedsystem with less tensioned back lines. It is impossible to get kite at lower AoA than its designed parameters allow.

"The initial application is to increase depower (allow a smaller AoA without using the trim strap or clamcleat) rather than increase power (aim is to keep same maximum AoA than with standard bar)." -Regis

It gives more AoA change range for normally used bar movement. How this larger range is used depends many things, some of then are personal choices.

"I would just add that in very light wind (say below 7 knots), backstall is frequent even with standard bar if you pull too much on the bar." -Regis

Good point. L/D ratio is variable, in low winds it is much lower. So backstall is present earlier.


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