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Bridle Shrinkage

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kitexpert
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Re: Bridle Shrinkage

Postby kitexpert » Tue Mar 17, 2020 12:06 pm

I'm not sure why people want to bundle different things together like "long mixer test" does. Ok, it is simple and usually effective but if there is more difficult issues when this kind quick fixes don't help it is better to be more systematic. I mean to find out where issues really exist and to fix them where they are, so not to do some general adjustments which may correct (more or less) the original issue but also develop new issues.

Many new kites (Soul, Hyperlink, Sonic3) have similar line lengths in different parts of the bridle. This makes comparing and measuring those line very easy.

Systematic way to adjust a foil kite is:

1) Check and adjust flying lines. Front/backlines should be equal to a known manner

2) Check and adjust mixer. Pulley lines do shrink a lot. If you have adjustable mixer just adjust it to level. If pulley lines are worn out, replace, they can be 10% shrunk at this stage. If mixer is not adjustable replace pulley line(s) or make your own adjustment system. Mixers are quite simple things, nowadays 1:2:4 two-pulley mixer is a standard and it is not difficult to make one from dyneema line and some pulleys. Mixer length is not at all critical, it just have to be long enough and level.

3) Check the bridle. I always start from the most suspicious lines by comparing them to line plan. This means long thin lines which don't have much load on them, they have the biggest shrink. If differences are found it is best to measure more lines to find out how bad kite is in general and where issues are.

4) Correct shrinkage. There is different ways to do it: 1)to stretch 2)to make adjustments by knots or extensions 3)to replace lines. I suggest stretching for the bridle because it is fast and clean way to do it. With an assistant and doing it from both sides of the kite simultaneously its not that big job and symmetry is remained. After some pulling and referring to line plan you will find out how much force you need to restore original line length. You will also feel how stretching affects, shrunk line gives in and then becomes stiff. Replacing the whole bridle is for sure effective but there is quite a lot work and expenses and it is silly because lines themselves are not damaged.

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Re: Bridle Shrinkage

Postby Adventure Logs » Tue Mar 17, 2020 5:50 pm

kiteykitekite wrote:
Tue Mar 17, 2020 2:29 am
Adventure Logs wrote:What’s your method for the bridle restretch.
I know you didn't address me but a weight through a pulley. I don't usually do it anymore though, as it's quicker and much more permanent to adjust things.
Adventure Logs wrote: Only thing annoying about the long mixer test is you need someone to help you.
I have never done one, but having done much more complicated things I see no reason you couldn't do it solo. 2 ways is to use screw drivers likely 6 to secure ABCZ so black marks align at the kite and then pull against them securing your front and rear main. You adjust B and C as needed to have them right and AZ right. Another way is to secure both front and rear main with screwdrivers. Check and measure A to Z marks. Adjust the front and rear main with measurements. Check AZ marks align then measure BC marks. Adjust BC with measurements. Check and repeat anything you need to.

You do this all on some flat grass ideally under a tree with no wind and the screw drivers go in the ground. You can do it other ways and places.
tkaraszewski wrote: There's no other tuning to be done here, the kite should be tuned correctly, albeit with slightly short steering lines?
The other important thing you are missing is the mixer depower limit. While the LMT seems great it only accounts for the kite at one point in the span and not for other factors like your personal preference and the condition of the kites fabric etc. To account for all of these it is easier to one restore the mixer depower limit or maybe increase it 2 or more cm from standard, do a mixer test, and then adjust Z till you have a kite that flys how you like. You will most likely have to lengthen Z ~10cm, but maybe more or less. I have experimented with increasing the depower limit 5-7cm over standard and the results are very good. It is more important for very light wind. If you have a kite that will sit above you but ends up on the water and won't fly forward, it is because the mixer is not allowing it to depower enough or reduce it's AoA to fly forward. With such an increase you will get interesting effect when the kite approaches it's stall point in light wind, instead of just stalling it will start to drift back deeper into the window. You also get the benefit of more range, through more depower and a faster flying kite. When you increase the depower beyond standard you will notice more depower when flying through the window.
I can’t take advice from you, I don’t know you. Now if it was from my good old buddy foilholio, well that’d be different.

Thanks Tomlutz. I just haven’t done a long mixer yet so don’t know. It looked like I’d need help but I’ll try it out.

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Re: Bridle Shrinkage

Postby Tomlutz » Tue Mar 17, 2020 6:11 pm

Adventure Logs wrote:
Tue Mar 17, 2020 5:50 pm

...

Thanks Tomlutz. I just haven’t done a long mixer yet so don’t know. It looked like I’d need help but I’ll try it out.
It is essential to first align A and Z. You can attach the lines to two screwdrivers just likt Armin did in his video (1:25 - for the short mixer test, but it is the same for the long). I used the pins of a garden fence instead of the screwdrivers.

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Re: Bridle Shrinkage

Postby kiteykitekite » Tue Mar 17, 2020 10:52 pm

If you replace pulley lines for shrink you would ideally be doing it every 10hrs.... Far better to adjust things than replace.

I forgot Armins aligning method it is good too, though it will affect B and C levels. If the pulley lines at not in a tight V they will be shorter, so the adjustments made will be longer.

Honestly though for all the messing around these things aren't worth it. Set the depower limit, and adjust Z a few times and it should be fine.


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