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The problem with flysurfer mixers.

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foilholio
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The problem with flysurfer mixers.

Postby foilholio » Sun Apr 10, 2016 6:18 pm

Firstly the good thing about FS mixers, they have adjustment. Mixers without some type of adjustment quickly go out of tune. Using foils it is essential to be able to make changes at the mixer to keep it in tune and to also compensate for changes in the kite's bridles or too tune the kite alternatively. Well done Flysurfer, boohoo most late comers.

Now the problem with flysurfer mixers. The way they test for changes in the pulley lines or A and Z mains has a couple of problems. First the pulley lines are folded when tested. Any shrinking in the pulley lines is only accounted for at half what it actually is. Strange as it is and one of the quirks of the universe that. Why is this a problem? Well most all foils depower onto A and B. Let B out too much and the kite inverts and is unstable depowered. Not enough and you miss out on some depower. To limit B the pulley for B will hit some limit, usually the end of the pulley line. But then there is more advanced foils, these can fly on A alone which is most flysurfers. Now maybe for German efficiency or just to keep the slightest of tension in a part of the B bridle, flysurfer too sets the limit of the B pulley to be right at the limit of B on the kite. Both these cases have a problem. If the pulley lines shrink the limit for B becomes less and so with it the depower. Now flysurfer has adjustments but unfortunately they only account for half the change, as explained. One good thing about the FS mixer is the limit for B is actually C, as the B pulley line is a bit longer than C it's limit is never reached, only that of C is. So we only need worry about C pulley line, sort of:-) Now lets talk about the worst case, C pulley line shrinks 10% so 10cm. After a mixer test and changing for the ratios of B it only leaves it 2.5cm too short. Not much? Well it actually is a lot. It's the same as if you permanently limited the effective depower throw by 10cm on any kite. The effects are more stally, loss of low end, loss of top end, slower turning,but take note the kite will be more stable! Now into the next problem and how to fix it. Z loves to shrink, this is the main problem with kite bridles, but also Z main will shrink. Z main being shorter than A main has the wonderful effect of making the B and C mains even shorter after a mixer test, further reducing depower. Ah but now what if I just made Z longer and did the mixer test again? well that would fix it all. But how much? Well you basically need to extend Z as much as C pulley line has shrunk plus A and Z main difference. You could extend it a little more to account for some shrink on the kite, but that is very touchy feely and restretching all the bridles is a good route for that you can even restretch Z main. After you have extended Z, a mixer test will have extended everything to the right lengths. Now you may run into the problem that C( thanks flysurfer) has run out of adjustment, you may need to make a very small 2-4cm extension to be placed on the end of the C main , the end of it then becomes what you line up on a mixer test. If you were to place it lower on the C main the B pulley line would now be limited so don't do that. But wait how do you extend Z? Make a knot at the desire extension length on the rear main/pigtail and move C pulley line there. Effect is Z is extended but you will need to adjust your line lengths as this changes them. There is of course other ways to make this adjustment. You could extend C pulley line, but you will also need to extend B pulley line. You could do this with one extension for both on the front. Could be simpler. But by moving the C pulley line to a knot you can move it to other knots or the ELC or the Z main rear main join and change the kites profile but also the line tune a bit as well. Lastly you could change out the pulley lines for new ones and this will fix the problem. But they will shrink quickly too.

One more thing? Have you ever changed pulley lines done the mixer test and the kite was unstable? Well the reduced depower on shrunken pulley lines is more stable and old foils become porous and this is most noticed as loss of rigidity when depowered, i.e. things flap and collapse.


Too much? Maybe paragraphs would have helped?:-)

Have a play with this
FLYSURFER MIXER Z MOD CALC EXCEL.zip
(8.4 KiB) Downloaded 89 times
UPDATED

EDIT HOW TO DO

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.
Last edited by foilholio on Fri Jul 08, 2016 3:37 am, edited 6 times in total.

plummet
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Re: The problem with flysurfer mixers.

Postby plummet » Sun Apr 10, 2016 7:26 pm

I found the mixer provided good adjustment. But I had to adjust the mixer often. So maybe the mixer moved under load? The chrono I have does not have adjustment. But also doesn't go out of alignment quickly.

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Re: The problem with flysurfer mixers.

Postby foilholio » Mon Apr 11, 2016 12:22 am

I am almost certain the rings can slip. Also when adjustments are made they always tighten and extend further after use. So to get alignment, guessing them a bit shorter is necessary and or trying by hand to tighten them a lot is another.

On the chrono if through some miracle those orbit don't get sand in them they will reduce the pulley line shrink. Maybe also ozone doesn't prestretch the pulley line and or possibly installs it slightly longer than spec? Their use of thin bridles will reduce the likelihood of them shrinking. There is an adjustment for Z on ozone mixers. Z is the most effectual on the kites behavior. The short length B pulley line looks like it will limit B. Being shorter should also reduce it shrinking.

plummet
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Re: The problem with flysurfer mixers.

Postby plummet » Mon Apr 11, 2016 1:06 am

foilholio wrote:I am almost certain the rings can slip. Also when adjustments are made they always tighten and extend further after use. So to get alignment, guessing them a bit shorter is necessary and or trying by hand to tighten them a lot is another.

On the chrono if through some miracle those orbit don't get sand in them they will reduce the pulley line shrink. Maybe also ozone doesn't prestretch the pulley line and or possibly installs it slightly longer than spec? Their use of thin bridles will reduce the likelihood of them shrinking. There is an adjustment for Z on ozone mixers. Z is the most effectual on the kites behavior. The short length B pulley line looks like it will limit B. Being shorter should also reduce it shrinking.
I have replaced the speed system bridles and pullies on my chrono v1. By the time the mixer is out the speed system lines needs changing anyway. Simply buy or make another set. I'm expecting to replace the speed system every year. I could push it out longer. But i'm jumping to leg breaking heights on land. A speed system failure at height = broken legs probably.

foilholio
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Re: The problem with flysurfer mixers.

Postby foilholio » Mon Apr 11, 2016 1:23 am

So you replace for shrink and not wear? I would have guessed the thicker pulley lines on the ozones would last longer than the FS stuff.

Broken pulley lines probably won't kill on land but the likely hood of permanent serious disabling injury is very high. I know on water with a total failure I can usually get back to the beach kite still flying. The advantage of a covered line like FS uses is it will usually fail in two stages, giving time to stop before total failure. The warning is the pulley motion changes drastically or starts to jam or catch. Are you not concerned with the thinner bridles failing especially cascade failing? Compared to paragliders even FS bridles are thin, the chrono is like fishing line. Although Ozone did change the chronos bridles a few times and they are thicker now?

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Re: The problem with flysurfer mixers.

Postby PullStrings » Mon Apr 11, 2016 2:16 am

I witnessed 2 guys doing a mixer test while drinking several cans of that beer
They had a few screwdrivers planted in the grass and they were going back and forth about how to go about it
It was the greatest comedy act ever

Image

foilholio
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Re: The problem with flysurfer mixers.

Postby foilholio » Mon Apr 11, 2016 2:23 am

The mixer test is actually quite easy and quick, less than 1-2 min each side. You only need stand on the front and rear lines together with one foot, no screw drivers needed.

It may seem a bit long and complicated what I have written, but I am just trying to explain it better. A video a few minutes long and I could show it all quite well. Or a picture. As they say a picture is worth a thousand words.

Z MAIN adjustment.JPG
Z MAIN adjustment.JPG (53.11 KiB) Viewed 1126 times
C MAIN extensions.JPG
C MAIN extensions.JPG (52.62 KiB) Viewed 1126 times

Mossy 757
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Re: The problem with flysurfer mixers.

Postby Mossy 757 » Mon Apr 11, 2016 3:45 pm

So what is the problem with flysurfer mixers? That they're adjustable or that they deform disproportionately to their competitors?

foilonfoil
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Re: The problem with flysurfer mixers.

Postby foilonfoil » Mon Apr 11, 2016 5:29 pm

IMO, I have had no issues with my mixers on my three Sonics. Replaced the pigtails with the little rings on the kite side with traditional pigtails and I'm using Ozone Race Bars.

foilholio
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Re: The problem with flysurfer mixers.

Postby foilholio » Tue Apr 12, 2016 2:17 am

:roll: The problem is not that they are adjustable or deform quicker. Noticing the problem is some what subtle but becomes worse as the pulley lines age and the kite gets used at it's limits. Because the shrink is day to day slow type thing, if that is all you can notice it is unlikely to be very apparent at all.

I will summarize. The mixer test only corrects half of the shrink on the pulley lines. This effects the final AB depower point, the limit to how long B can be compared to A.

A simple way to test for this is if when you fully depower the kite. You may need to pull on you depower strap or front line leader to get maximum depower. Now does the full B bridle still look really tight? It shouldn't. Alternately you could just measure your C pulley line, if it is less than 100cm, B is not being fully released. But also on an old kite the B bridle will have shrunk as well and C pulley line would need to be slightly longer than 100cm to fix this, which it won't of course.

I will also add if you attempt to use the mixer to correct for bridle shrink(i.e. kite not flying right), the correct settings for this are C and B being shorter. Doing so will also reduce the AB depower point. It can create a bit of a conundrum for some one fiddling with a mixer trying to get a kite to fly like it should. Been there done that.

I actually have quite a few ideas to improve upon the mixer. Flysurfer hasn't really made any major changes to it since they released the pyscho4 in 2008. Only recent change was to remove the WAC line which I dare say they should put back. The mixer is not a terribly complicated device, it's just a few bits of string, knots, splices and pulleys. I think with a focus on simplifying it and increasing it's function, it can be improved quite a bit. Evolving it would be even easier. I am surprised with updates to kites no such effort is made for the mixer.


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