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The problem with flysurfer mixers.

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foilholio
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Re: The problem with flysurfer mixers.

Postby foilholio » Sat Apr 21, 2018 1:32 pm

Comparing and adjusting relative to A should be ok, if you where comparing B and C against A and Z leveled in the LMT then you would have a bigger problem with depower.

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Re: The problem with flysurfer mixers.

Postby Jzh_perth » Sat Apr 21, 2018 1:46 pm

From the point of view of a retailer who often sells secondhand FLYSURFER’s - can someone clarify for me how effective the short mixer test (levelling AZ then BC) and regularly replacing the pulley lines is ? Much of what I read in this thread seems to relate to the SMT not correcting for shrinking pulley lines - it all makes sense, but it’s such an easy thing to do I tend to do it on all second hand kites I sell. Installing a new bridle would not be an option for obvious reasons.

In my personal experience the FS foils tend to need more trim pulled on to stop backstalling as they age, but otherwise still fly pretty well. To me that’s a sign of short steering lines and easily rectified.

I’m curious how much performance new SPL and a basic mixer “balance” can restore compared to when the kite was new ? Does this correct a majority of the problems ? What else can I do to look after the customer ?

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Re: The problem with flysurfer mixers.

Postby Kamikuza » Sat Apr 21, 2018 3:50 pm

Jzh_perth wrote:
Sat Apr 21, 2018 1:46 pm
From the point of view of a retailer who often sells secondhand FLYSURFER’s - can someone clarify for me how effective the short mixer test (levelling AZ then BC) and regularly replacing the pulley lines is ? Much of what I read in this thread seems to relate to the SMT not correcting for shrinking pulley lines - it all makes sense, but it’s such an easy thing to do I tend to do it on all second hand kites I sell. Installing a new bridle would not be an option for obvious reasons.

In my personal experience the FS foils tend to need more trim pulled on to stop backstalling as they age, but otherwise still fly pretty well. To me that’s a sign of short steering lines and easily rectified.

I’m curious how much performance new SPL and a basic mixer “balance” can restore compared to when the kite was new ? Does this correct a majority of the problems ? What else can I do to look after the customer ?
If I've understood foilholio's posts, shrinking SPL aren't an issue so long as you don't run out of adjustment and/or the depower isn't compromised with the shortened travel.

I think it's good service to replace the SPL on the used kites you sell :thumb:

More trim needed makes sense -- both Gunnar and foilholio have said that Z shrinks the most slash a lot. If that's the case, that means aging foils are getting increasing more camber as B and C are shrinking too, even if you're zeroing the mixer and your lines. Then LMT becomes necessary if it's not flying right.

Which may not even be necessary...

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Re: The problem with flysurfer mixers.

Postby foilholio » Sun Apr 22, 2018 8:12 am

No I think you have misunderstood, the shrinking SPL are an issue even if you do have standard adjustment. As soon as the SPL become shorter than factory length you have lost depower. SPL when new are shorter than factory, SPL when old are even shorter. Low end stall can be highly affected by loss of depower. As well as topend which is obvious from a loss of depower and things like low end power from flying the kite suffer and jumping. Generally loss of depower makes the kites shitter. I am still surprised till now why something like a Z-mod or adjustable SPL are not standard on every kite( and also why B SPL is so long).

Also don't forget upper bridle shrink reduces depower as well!


As to camber change with shrink, I think things tend towards less camber not more. You would need MORE than double the shrink of Z than C before you get any camber increase! What you will probably find with most shrink is C is engaging now too early creating earlier stall and less stability.

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Re: The problem with flysurfer mixers.

Postby Mossy 757 » Sun Apr 22, 2018 11:09 am

foilholio wrote:
Sun Apr 22, 2018 8:12 am
As to camber change with shrink, I think things tend towards less camber not more. You would need MORE than double the shrink of Z than C before you get any camber increase! What you will probably find with most shrink is C is engaging now too early creating earlier stall and less stability.
phpBB [video]


If you're rehabing a used flysurfer, SPL swap and short mixer test is a good starting point. If the kite is very old, Z extension might be appropriate to account for bridle shrink, buy with my old Sonic1 the SPL swap was like a miracle.

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Re: The problem with flysurfer mixers.

Postby foilholio » Sun Apr 22, 2018 1:20 pm

Yes BUT you can achieve the same and in fact better results without the SPL swap. If your pulley lines are worn sure swap them, but trust me you'll be getting less than a quarter of the life out of pulley lines if you are swapping them just for shrink. Then there is the upper bridle shrink which you won't fix with just new pulley lines or B and C. If you're on a remote beach with no new pulley lines and would like a bit more performance? Z-mod.

Even with new pulley lines I often set my mixer on the middle knot then I can move either way for more stability or more performance. Nice simple little option can't understand how it's not standard setup. Flysurfer could add a couple more knots and length and most mixer adjusts through B and C could be avoided, undoing a larks head and moving it is so much simpler to think with and do. Think of it, "oh your kites doing this" move it down a knot and try that. Easy. Technically it would be better to move Z and not the pulley line, which would be easy to design.

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Re: The problem with flysurfer mixers.

Postby Henk » Mon Apr 23, 2018 2:57 pm

foilholio wrote:
Sun Apr 22, 2018 1:20 pm
Yes BUT you can achieve the same and in fact better results without the SPL swap. If your pulley lines are worn sure swap them, but trust me you'll be getting less than a quarter of the life out of pulley lines if you are swapping them just for shrink. Then there is the upper bridle shrink which you won't fix with just new pulley lines or B and C. If you're on a remote beach with no new pulley lines and would like a bit more performance? Z-mod.

Even with new pulley lines I often set my mixer on the middle knot then I can move either way for more stability or more performance. Nice simple little option can't understand how it's not standard setup. Flysurfer could add a couple more knots and length and most mixer adjusts through B and C could be avoided, undoing a larks head and moving it is so much simpler to think with and do. Think of it, "oh your kites doing this" move it down a knot and try that. Easy. Technically it would be better to move Z and not the pulley line, which would be easy to design.
Foilholio, I have a few questions with respect to B limited depower and your Z-mod.

- If B limits the depower after the SPL has shrunk, is it not possible to increase depower range by changing the front/rear line ratio (enlarge rear lines or shorten front). I can imagine B limits but C an Z will then be able to further extend. Maybe this is not as much depower you would get with making B unlimited, but it might help a bit. The foil surface will not be as efficient though (there will be a dent near B). And you will lose power sheeted in. For low wind this could be a workaround.
- Your Z-mode changes the point where C pully attaches Z-main. Is it therefore needed to adjust front lines accordingly?
- To tune a used foil, what are the best steps to follow? Maybe next sequence:
1. Measure A/B difference and do the Z mod with the deviation from 25 cm
2. Mixer level, if needed extend C if not enough SPL available (or swap SPL, or would that mean you swap the SPL way earlier then normal wear would require?)
3. Long mixer test to level cord-wise bridle shrink (where Z is typically shrinking most and A the least)
4. If the kite has many flying hours, span-wise shrinkage might result in too short wing tip bridles. Compensate by comparing wing tip bridles with line plan and make extension loops from LCL bridle material to be placed between kite and bridle.

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Re: The problem with flysurfer mixers.

Postby Mossy 757 » Mon Apr 23, 2018 4:46 pm

foilholio wrote:
Sun Apr 22, 2018 1:20 pm
Yes BUT you can achieve the same and in fact better results without the SPL swap. If your pulley lines are worn sure swap them, but trust me you'll be getting less than a quarter of the life out of pulley lines if you are swapping them just for shrink. Then there is the upper bridle shrink which you won't fix with just new pulley lines or B and C. If you're on a remote beach with no new pulley lines and would like a bit more performance? Z-mod.

Even with new pulley lines I often set my mixer on the middle knot then I can move either way for more stability or more performance. Nice simple little option can't understand how it's not standard setup. Flysurfer could add a couple more knots and length and most mixer adjusts through B and C could be avoided, undoing a larks head and moving it is so much simpler to think with and do. Think of it, "oh your kites doing this" move it down a knot and try that. Easy. Technically it would be better to move Z and not the pulley line, which would be easy to design.
My Elf has Z pigtails, and you're right, it's definitely an easy-mode swap for more power/stability based on what the wind is doing, but for most people I would not recommend that mod on a Flysurfer as simply replacing stock parts and using the built in tuning system just seems so much easier and reliable. I get that you won't ever get back to factory tune, but I've not flown
a kite where it was close enough to matter.

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Re: The problem with flysurfer mixers.

Postby Mossy 757 » Mon Apr 23, 2018 4:49 pm

Henk wrote:
Mon Apr 23, 2018 2:57 pm
- To tune a used foil, what are the best steps to follow? Maybe next sequence:
1. Measure A/B difference and do the Z mod with the deviation from 25 cm
2. Mixer level, if needed extend C if not enough SPL available (or swap SPL, or would that mean you swap the SPL way earlier then normal wear would require?)
3. Long mixer test to level cord-wise bridle shrink (where Z is typically shrinking most and A the least)
4. If the kite has many flying hours, span-wise shrinkage might result in too short wing tip bridles. Compensate by comparing wing tip bridles with line plan and make extension loops from LCL bridle material to be placed between kite and bridle.
5. Replace your quiver with Sonic Race's that have 3 pulley bridles that let you tune your wing tips apart from the rest of the kite :lol:

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Re: The problem with flysurfer mixers.

Postby foilholio » Tue Apr 24, 2018 4:05 am

Henk wrote:
Mon Apr 23, 2018 2:57 pm
Foilholio, I have a few questions with respect to B limited depower and your Z-mod.

- If B limits the depower after the SPL has shrunk, is it not possible to increase depower range by changing the front/rear line ratio
On the kites I have seen NO. This is a limit imposed by the mixer, stand on your front line at the mixer and pull on B, it stops and the rear line is slack. Extend the rear lines past this point will just make them more slack, observed as a bow or arc in the air. When you have some bow or arc in your rear lines you have no more depower at the bar. When you have a bow or arc in the B gallery of bridles you have reached the limit of depower for that kite ( without altering the sewn shape).

How do you know if your B is limiting your depower? Quite easy if when depowering your rear lines are slack but you B bridles are not :-). Now there also seems vary levels of slack, what might be slack at the windows edge may not be in the middle of the window. Best consult a line plan to understand the correct amount but you can tune it by feel. Z extended by what I did in the picture seems a good amount for shrunk pulley lines on flysurfers.

These methods of course only apply to foils that fly solely on A, but for kites that fly off A and B the AB limit is still important of course in fact more important as overextending it will cause collapses particularly inversions.
Henk wrote:
Mon Apr 23, 2018 2:57 pm
- Your Z-mode changes the point where C pully attaches Z-main. Is it therefore needed to adjust front lines accordingly?
Yes it will move your bar position, there is a wonderful thing call a trimmer to fix that :-) It will also change the sheet range/position of the kite, for that you may need to adjust your line lengths. The best way to trim lines is use the trimmer, adjust the lines when you are running out of trimmer. Advanced foil flying needs backstall so having that available with the trimmer is a must, even lines is kooky :-)
Henk wrote:
Mon Apr 23, 2018 2:57 pm
- To tune a used foil, what are the best steps to follow? Maybe next sequence:
1. Measure A/B difference and do the Z mod with the deviation from 25 cm
2. Mixer level, if needed extend C if not enough SPL available (or swap SPL, or would that mean you swap the SPL way earlier then normal wear would require?)
3. Long mixer test to level cord-wise bridle shrink (where Z is typically shrinking most and A the least)
4. If the kite has many flying hours, span-wise shrinkage might result in too short wing tip bridles. Compensate by comparing wing tip bridles with line plan and make extension loops from LCL bridle material to be placed between kite and bridle.
We get the 25cm from 1/4 of the factory 100cm C SPL, factor in some shrink of B in the upper bridles say 2cm and you have 27cm.

Do the mixer test, then measure the AB difference. Use Z-mod to get that up to 25 or 27cm with another mixer test. There is an explanation and excel sheet on the first page but I guess it's too complicated. If you measure say 23cm there is 4cm to get to 27cm you will need to extend Z 4x that 4cm so 16cm. If you want to get to 25cm that's 4x 2cm so extend Z 8cm.

Swap your SPL when they are worn not for shrink.

I have never (maybe once or twice a long time ago ;-) ) done a long mixer test I prefer to adjust kites to my liking a little from session to session etc( or switch setting with the Zmod). The shrink cord wise is usually in ratio so then there is no real need to correct it. The benefit most people would see from the LMT is an improvement of the AB limit. Same reason you see users like Mossy shout out changing pulley lines made such a difference, it's the improvement to the AB limit.

For Span wise shrink I have found restretching the bridles best. I have tried measuring and adjusting every bridle(with loops), many times and I have found it a waste of time. One of the fundamental problems with measuring bridles is the force used to measure them accurately (5kg) is enough to restretch them and in some cases as low 1 to 2kg will start restretching a bridle. You end up with measurements all over the place as 15-30kg is needed to fully stretch a bridle.

There is no doubt though making extensions to bridles to alter the span wise shape of a kite can have a dramatic effect on it, as I have seen with the Pansh Genesis and Aurora 1. Doing such you would think you would need to take all sorts of measurements and be really precise. but there actually seems quite a margin for error and you can really tweak here or there. Just changing the Z gallery on the Genesis was amazing. What seems important is symmetry, and that is what I emphasize when restretching. If you were considering altering the bridle I would try and probably stop at Z, it shrinks the most and seems to have the most effect on the kite, so largest benefit can be obtained altering it.


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