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The problem with flysurfer mixers.

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kitexpert
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Re: The problem with flysurfer mixers.

Postby kitexpert » Mon Aug 08, 2016 8:46 pm

foilholio wrote:Best upwind is with it lightly tensioned while B and C have more tension.
I don't know if it is reasonable to try to guess how big tensions different line rows have. I meant how much relatively different line rows must be pulled, to get fastest upwing. Like it is discussed earlier, this depends how much force kiter is able to use/how strong the wind is. Compared to original setup pulling more B-C does not improve upwind, because it lowers the camber. In original system camber usually slightly increases when AoA increases, it is usually the best for the upwind and generally too.
foilholio wrote:This I have not so noticed maybe you mean it is less stable?
If you tighten very grossly brakes, B-C line rows do not function almost at all. Then kite is when powered in "high-camber-with flaps" setup. When sheeted in it generates quite a lot power, sheeted a bit more it stalls aggressively. It is so obviously wrong that I've not even tried to use setup like it more than for awhile.
foilholio wrote:Lift will be lost but L/D can improve. Didn't we discuss this before? :-)
Yes, no need to argue.
foilholio wrote:True but they all fold at some point.
No. It is very well possible to change AoA of the foilkite without any shape distorsions. Then camber stays the same. However it is observed it is beneficial to increase slightly camber when AoA is higher, even though some distortions are produced.

Folds are seen when some linerow (B-C) is tighter/looser it should be. Of course if brakes are too tight they produce a fold somewhere in between C-Z. Some small fold is however tolerable when fully sheeted in, how much is a bit matter of taste. Trend is to towards conservative brake tightness, because if too tight too much drag is produced.
foilholio wrote:Big incorrect there. They all interrelated i.e. tension one it loosens the other.
If brakes are loose, it kicks in later when sheeted in - however always 1:1. If tighter, then B-C comes later. Just two different views for the same matter, no need to argue here.
foilholio wrote:Nope both can affect it.
Of course. But there is limited possibilities to change pulley ratios (if not use one method I've tried years ago). Line row locations instead are quite freely choosable.

foilholio
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Re: The problem with flysurfer mixers.

Postby foilholio » Tue Aug 09, 2016 1:32 am

kitexpert wrote:I don't know if it is reasonable to try to guess how big tensions different line rows have.
Not too hard to observe but observing things is not your forte.
kitexpert wrote: I meant how much relatively different line rows must be pulled, to get fastest upwing. Like it is discussed earlier, this depends how much force kiter is able to use/how strong the wind is. Compared to original setup pulling more B-C does not improve upwind, because it lowers the camber. In original system camber usually slightly increases when AoA increases, it is usually the best for the upwind and generally too.
Depends which kite we are talking about, but the flysurfers I have seen, most of them, reducing camber a bit improves upwind. Also depends on the wind, lower camber it's harder to go in light wind.
kitexpert wrote:"high-camber-with flaps" setup
trying to weasle your way out now lol. It's not high camber but "with flaps".
kitexpert wrote: I've not even tried to use setup like it more than for awhile.
not very expert are you then?
kitexpert wrote:Yes, no need to argue.
OMG! so you agree , some of those links must of done something. So I will let you have your "flaps" thing and we can settle that we just disagree what a "high amount" is. I can provide some links about negative camber or "flaps" now if you would like?
kitexpert wrote: It is very well possible to change AoA of the foilkite without any shape distorsions.
Yes but it is limited to a narrow range. You can't not distort with say just A and B nor at high amounts of Z or any of the bridles. There is a point were they are all in sync and the rest they are not.

kitexpert wrote:Of course. But there is limited possibilities to change pulley ratios (if not use one method I've tried years ago). Line row locations instead are quite freely choosable.
What is the furthest forward you have placed B?

kitexpert
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Re: The problem with flysurfer mixers.

Postby kitexpert » Tue Aug 09, 2016 10:33 pm

foilholio wrote:Depends which kite we are talking about, but the flysurfers I have seen, most of them, reducing camber a bit improves upwind.
I don't believe this is true. But because going fastest upwind is very complicated thing sometimes that kind of impression may occur. It must be remembered that with FS camber slightly increases with higher AoA. So, if you have tweaked camber to lower similar camber is possibly reached later, at higher AoA than before. It doesn't sound a good idea, but for some wind speed, for some kite size and for some kiter strenght this new combination may be better than original. In most cases it is worse. If you tweak camber a lot lower, it is certainly worse.
foilholio wrote:trying to weasle your way out now lol.
Like I earlier wrote producing high camber with tight brakes ("flaps") is stupid and your examples were too.
foilholio wrote:not very expert are you then?
Expert enough to not waste my time with stupid mixer setups.
foilholio wrote:OMG! so you agree , some of those
I don't want to argue with you if you don't care about the facts I tell.
foilholio wrote:Yes but it is limited to a narrow range.
AoA range is limited by the sheeting range. For a smaller kite sizes it is more than they can tolerate, it is possible to backstall them. Without producing distorsions to canopy, if kite is designed to do so.
foilholio wrote:What is the furthest forward you have placed B?
In my own designs I have used 1:2:4 speedsystem since it became generally used. It is simple system which does its work. Earlier lower pulling ratios for B were used, then B could be located closer to A. Some kites had fixed A-B, then spacing between them was quite close. This increased stability but decreased depowering, AoA was fixed in that area.

If B is pulled 1:4 it can not be very close to A. If it was, then camber would decrease when powered up, not a good idea. Typical line row values are easy to measure from some kite, perhaps not Pansh though :D Speeds3-5 are reasonable.

RudiCan
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Re: The problem with flysurfer mixers.

Postby RudiCan » Wed Aug 10, 2016 3:46 pm

I bought a used flysurfer speed 3 12m, so this is a very practical question (from a very newbie) as I've just replaced the flying/main lines and struggling with the setup.

How tight the backlines supposed to be when the kite is sitting at the zenith and the kite is completely depowered, the bar pushed out and the trimmer is set to the shortest/fully depowered? Should the back lines be fully taught in this scenario?

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Re: The problem with flysurfer mixers.

Postby foilholio » Wed Aug 10, 2016 3:47 pm

no

RudiCan
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Re: The problem with flysurfer mixers.

Postby RudiCan » Thu Aug 11, 2016 12:58 am

Thank you.
So when the bar is fully pulled in and the depower straps are fully out, the line ends nicely line up, they are at the same level at the bar end. They are exactly the same length, so the kite end of the lines nicely levels too. The sparepartlines are brand new, so no shrinkage. The mixer test seems to be OK, the lines in one level.

The problem is that the kite has no power. it goes up to the zenith, but when I pull in the bar, there is very little lift, the kite just starts slowly going backward.
Question 1: Do you have any idea what can cause this?
Question 2: What's the purpose of the rest of the depower? The bar has 40cm range to move, in the top 20cm the steering lines are slack, only the lover 20cm has any effect when the kite is at the zenith.

foilholio
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Re: The problem with flysurfer mixers.

Postby foilholio » Thu Aug 11, 2016 1:26 am

They should be the same level at the kite end, they won't match at the bar end because the rear lines shrink and to compensate you shorten the black front line leader or the trim strap. It is nice to have some backstall to help control foils too, so rears a bit shorter than level at full power. If you use something like the Z mod discussed here this will change the trim level as well. Combine that the stall point of the kite which should be where the bar is fully in actually changes with wind and apparent wind speed, and every ones arms are different lengths and riding different, there then is not an exact line matching that is perfect for everyone and every condition. This is why you have a trim strap to adjust! To adjust the line lengths then just use the trim strap, feeling where the stall point is or where you like the bar position when riding. Then when you find you are running out of trim strap, you can then adjust the line lengths. You should generally always be running out of depower as it is the rears shrinking. So when you are at max depower, and the bar is too far out or feel too much depower is pulled for the bar to be in a comfortable position, either land or between sessions just shorten the black front leader an inch or 2. Continue like that till you get the right length. Or you can look at the how much the trim strap is shortened to get the correct bar position and the shorten the black front leader for that amount and say minus one inch so you have some margin. If you over shorten or for some reason the kite isn't powering or stalling enough you just do the reverse and lengthen that line.


TLDR; Use the trim strap to adjust the lines, when the trim strap runs out adjust the black front leader line.


Answer 1 the kite is back stalling , foils need to be flown. The mixer and the kite may be out of tune. Try lengthening C 1 inch while keeping B level.

Answer 2 I thought you had taught rear lines depowered? They do go quite slack depowered, and just because they are slack doesn't necessarily mean they aren't doing something at the kite(though not much). There is vary degrees of slack, a slight bow is still doing something. You can power foils more when you are riding too. The mixer at new has 2meters of total range, worn it is ~1.8m. Some where around half is used for landing and relaunch, though some of that can be used to steer and ride.

Oh and brand new spare part lines can be shrunken :-/. Not that that is your problem.

RudiCan
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Re: The problem with flysurfer mixers.

Postby RudiCan » Thu Aug 11, 2016 2:50 am

the flying lines and the A B C Z main lines are brand new and the mixer is perfectly aligned.

But you are the king with the line shrinkage idea!

I just checked out the BR main extension, which goes from Z main to the back of the kite. According to the line plan it should be 242.8 cm and the actual length is 239.8 cm, so it shrunk 3 cm.
The C main extension (from the C main to the 3 C1,C2,C3) supposed to be 169.9cm, actually it is 167.8cm. So that shrunk 2cm.
The B main extension (from the B main to the B1, B2, B3) supposed to be 85.1, actually it is 84.5. So that shrunk ~0.5 cm (but it is a shorter line, the proportional shrinkage is 1 cm compared to C main)
The effect of the shrinkage is the same as if the C main would be ~2 inches shorter than it should be and B main would be 1 inch shorter, and the result is the ugly backstall and no lift! So like you said, I need to lengthen C main to compensate for the line shrinkage.

It seems based on the rough estimate that the C main should be lengthened by 2 inches and B main should be lengthened by 1 inch, but it seems from the above that B main should be lengthened too, maybe by 1 inch. Does this sound OK based on your experience?

Thank you for the help man, without you I would be deeply desperate!

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Re: The problem with flysurfer mixers.

Postby PullStrings » Thu Aug 11, 2016 2:54 am

foilholio wrote: One more thing? Have you ever changed pulley lines done the mixer test and the kite was unstable?
No...kite flew perfectly all the time afterwards... when i did it
I think the problem is with foilholio overwhelming expertise

Get an LEI kite and the problems you have will disappear

Image

RudiCan
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Re: The problem with flysurfer mixers.

Postby RudiCan » Thu Aug 11, 2016 3:45 am

Who needs what probably depends on that person's needs, right? What I need is depends on me. I'm close to 50, 200 pounds, can't really swim and live in Toronto with not much wind or beaches. The odds are that you are very different from me me, right? :) If I don't have a question in a topic and I don't know the answer to any question in the topic then usually I don't post anything.
Here I had a question about the mixer, and thank to foilholio's expertise and his wish to share it with those who interested in this topic helped me to solve my problem and I thank him for that.

Off topic: I'm completely newbie. I bought an old LEI and this flysurfer foil kite. After playing with them a little bit I will tell you which one I prefer. Although my preference later might change as I'm learning. And as you can see I'm going to have a steep learning curve. :)

Really off topic: I'm amazed by this German engineering. (the classic one, not the Volkswagen-kind) Although did you know, that they lost the 2nd world war because of their engineering? Their precision guns froze up in the Russian winter, while the crap Russian guns worked.


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