The problem with flysurfer mixers.

[foilholio]

Well a thinner LE would be in the same flying style as the kites above. I like the idea because I like light kites for surfing. Sure using large inflatable tubes and carbon will achieve aerodynamic nirvana but first crash will go crunch and pumping will take very long, well unless you use the same tube size and a thinner airfoil. Maybe race kiters will go for it. For me I don't see how adding a solid structure inflatable or otherwise can make the kites lighter or more durable. Hell I don't even like the plastic flexible battens on foils. Kites inside a wave are like clothes in a washing machine, I am sure you can imagine what a carbon rod would do to a load of laundry.

[foilholio]

So the quickest and easiest way to correct for this is after a mixertest/level to measure the difference between A and B when fully depowered. Basically stand on the frontmain or line and pull A and B up and measure the difference. Your best make the Z mod before you do this, but place the C pulley line end on the rearmain/zmain join. This is because it will shorten the C pulley line a little because of the larks head and so change the AB measurement. Anyway you measure the AB difference fully depowered and it should be 25cm ( 1/4 of the 100cm C pulley line) if the pulley lines are the correct length. They won't be so you move the Z main knot down 4x that difference, measured from the bottom of the Z main to the bottom of the knot. If you have done something like a long mixer test you can add the difference of B to your AB difference, it will probably only be 1 or 2 cm but is not as important as correcting the mixer. Then redo the mixertest and adjust your flying lines. As stated before you may need to extend C main if you run out of adjustment. Finally remeasure the AB difference to check it is correct.


I am also trying to come up with a better way to make adjustments to the mixer and generally improve it.

[foilholio]

From a PM with permission.

Your knowledge might explain why some kites don't fly well even though the mixer test is ok.

It explains one of the problems but not all.

I have a few questions I hope you can answer:
- It seems that your Excel model of the bridle does not take into account the attachment point of the B-Pulley line to the C-main. It is mentioned in the comments, but wouldn't this have quite some impact as in effect the B-Pulley line will be longer than calculated?

I think it may not calculate the B main exactly correctly, but it is not necessary as I just made it to demonstrate how things interact. B Is being limited because of the C pulley line, so the length of B pulley line is not really important. Just because C adjustment changes B won't change a thing. They still get lined up the same and that leaves B too short any way you look at it.

- I would like to understand what kind of maintenance I need to do on my new 15m Speed5. I came up with next schedule:
+ Bar line length adjust after 20h (for shrinkage)

Adjust when you run out of trimmer adjustment or don't like it always being depowered.

+ Mixertest and bridle lines check after 60h

When ever you feel like it or feel the kite doesn't seem right.

+ Exchange pully lines after 100h

Pulley lines break with some warning, the outer sheath breaks which creates a noticeable bump when sheeting in/out. You don't have long to ride after that before the inner breaks though maybe 10-20mins depending how much and how you use the bar. You will probably miss the sign though, don't worry too much as the kites can still sort of be flown with a broken pulley line, I wouldn't want to be too far from shore though as mainly down wind riding is possible and the kite can collapse easy if you don't manage it well.

With experience you can tell when a pulley line or any line, depower etc, is too worn and needs replacing. Heavy fraying and broken strands is a strong indicator.

+ Exchange pully after 250h

Sprengers last a bit longer than ronstans, in practice ronstans wear out before the pulley lines and then proceed to destroy them. If the pulley has a lot of play or doesn't roll nice it should be replaced, I generally replace pulleys and pulley lines at the same time. You can feel at the bar when pulleys are worn, they give a notchy bump bump bump feel sheeting in and out.

* Is it also possible to re-stretch the bar lines and pulley lines, to prevent to need to make adjustments?

You can restretch any line but it would seem not to original length, so no. Pulley lines and front lines require perhaps more force than you can easily exert to restretch them. The rear lines can be restretched by throwing your whole body against them, and the fronts too but less so. You can break the rear lines so watch out. Good though rears are easy to restretch because they change/shrink the most. In generally though it is just easier to adjust the lengths as you end up in a continual cycle of restretch shrink and repeat.

* What is the difference between a long-mixer test and a normal?

A mixer test sets the mixer to level. A long mixer test sets the kites upper bridles to their original relationship at a level mixer, it does this by changing the mixer to some thing other than level. This is based on some measurement of the current upper bridle relationship and comparing it to what it should be calculated from the line plan. In reality the span of the kite is uneven so it is impossible to achieve. i.e. measuring and adjusting for one part is not correct for another. like center compared to tips.

- Can you clarify what is needed for your mod and when? So if I understand it correctly, you need to adjust Z and C to keep the mixer even AND the A/B ratio. What should I make for this, an adjuster for back line length? Isn't it easier to swap the pulley lines more often or re-stretch them? Or is it also about the bridle shrinkage of the main lines? Would you recommend to take measure of all lines, now the kite is still new?

Simply look at the pictures, it is a knot on the rear main which you move the end of the C pulley line to. You set the knot based on a measurement on A and B difference when fully depower , it should be 25cm. Then when you level the mixer it is all correct, you may run out of adjustment on C main, you can make an extension for it.

I have ideas to design a better mixer but have yet to go from paper.




If you don't mind can I post this in the thread so i don't need answer again the same questions?

Thanks

[Kamikuza]

Stand on the front main, and depower by . . . Pulling C risers? Where do we measure the difference?

Or just replace Z-main and the pulley lines?

Noticed my DIY SPL are shrunk (Amsteel) and Z-main is shorter than the A-main I repaired, even though I made it perfect length . . . and the performance has gone to pot

[Kamikuza]

PS have been using Cabrinha pulleys, whatever they are. Going strong . . .

[foilholio]

Stand on the front main or line and pull the B main till it is fully extended or fully depowered. When like this measure from the top of the A main to the top of the B main, 2 of the bits you line up in a mixer test. It should be 25cm because it is a 421 mixer, C SPL is 100cm and 1/4 of that is 25cm. You can make it slightly longer if you want to compensate for upper bridle shrink . If you want to adjust B shorter in the profile say to make it more stable but maintain full depower, just add that to you calculation. Any shorter than 25cm or even at 25cm considering the upper bridle shrink, will be more stable depowered than standard. Generally though you can always pull on a bit of bar if you need more stability, that is though as long as the profile is set right or that way.


Oh aswell, if you can observe your bridles and Z is always slack even with the bar in, which seems common for flysurfers, try loosening C while keeping B level in the mixer test. This will allow the kite to possibly be more stable while also allowing Z to tension and camber more giving it more lift. Maybe not the best upwind but it is more how they are when original. Understanding B and C better has been quite enlightening. Merely looking at the mixer producing AoA or a complete profile with ABCZ is wrong I think. A majority of change is merely A and B. If C or Z come in too early you get stability problems. If B or C come in too early or Z too late you lack lift. The setting for best L/D is not the best for lift or stability but it is more stable.

[kitexpert]

if you can observe your bridles and Z is always slack even with the bar in, which seems common for flysurfers

Of course Z must not be slack when fully sheeted in, it must be tighter. How tight, is a bit personal question. If Z is too tight kite becomes twitchy in its behaviour, if too loose turning suffers and some performance is lost.

Observing the line rows and possible folds in upper and lower skins tell a lot when adjusting kite bridle/mixer. It is easiest to see when some one else is flying the kite.

Merely looking at the mixer producing AoA or a complete profile with ABCZ is wrong I think.

That is what it does, it makes possible to change AoA of the kite by sheeting bar in/out. There is additional possibilities to fine tune camber and correct changes in mixer/bridle line lenghts. Almost certainly original settings are the best. Mixer tinkering means that some distorsions to panels will result and it has limited possibilities to correct bridle stretch/shrinkage.

Adjusting brake tightness is actually not mixer related matter, it is always pulled straight 1:1, with or without speedsystem.

If kite has increasing camber at higher AoA's it is related more linerow locations than the mixer, especially so with most common 1:2:4 mixer.

[foilholio]

Of course Z must not be slack when fully sheeted in, it must be tighter.

No not always. Best upwind is with it lightly tensioned while B and C have more tension.

How tight, is a bit personal question.

Isn't everything?

If Z is too tight kite becomes twitchy in its behaviour

This I have not so noticed maybe you mean it is less stable?

if too loose turning suffers

turning is different.

and some performance is lost.

Lift will be lost but L/D can improve. Didn't we discuss this before?

Observing the line rows and possible folds in upper and lower skins tell a lot when adjusting kite bridle/mixer.

True but they all fold at some point. Bulges also indicate.

It is easiest to see when some one else is flying the kite.

no doubt

Almost certainly original settings are the best.

what did you say?

How tight, is a bit personal question.

but yes original is good. The designer would have spent much effort on it, unless maybe Pansh

Mixer tinkering means that some distorsions to panels will result and it has limited possibilities to correct bridle stretch/shrinkage.

True and true. But the mixer and profile can only align at one single point, or at most a very limited range, for all others their will be distortions.

Adjusting brake tightness is actually not mixer related matter, it is always pulled straight 1:1, with or without speedsystem.

Big incorrect there. They all interrelated i.e. tension one it loosens the other.

If kite has increasing camber at higher AoA's it is related more linerow locations than the mixer, especially so with most common 1:2:4 mixer.

Nope both can affect it.

[grandeand]

Hello guys.
I wave a speed3 19.
I wanted to ask for the information.
since the dynema the castle, the mixer test cables and the cables of the bar, undergo the lengthening or shortening; how to return the speed3 19 to basics?
ok, low stop bar when the cables are equal, the mixer test A-B-C-Z all on the same, but with the castle how to behave?

[foilholio]

castle?