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Bridle Shrinkage

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JakeFarley
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Bridle Shrinkage

Postby JakeFarley » Mon Mar 16, 2020 1:51 am

I took the line plan for my 12m Soul and measured some of the bridle segments nearest the kite to compare them (the ones that I could measure.easily by myself - 1.5 meter length or less). I found that the leading edge segments compared the same and progressing to the trailing edge the segments progressively measured shorter (approx. 10-15mm) than the line plan showed. Also, I found that the segments at the wing tips measured shorter than the line plan. All the results were symmetrical from one side of the kite to the other.

The results did not surprise me as it seems to me that most of the load on the lines would be at the center of the kite, and more toward the leading edge. Thus the load would prevent line shrinkage at those locations

Has anyone done this and found the same results? Is this something to be concerned about?

My next step is to perform the short mixer test snd make any necessary adjustments.

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Re: Bridle Shrinkage

Postby kiteykitekite » Mon Mar 16, 2020 2:08 am

Shrinkage usually has a similar pattern. Standard mixer adjustments won't correct the kite fully. You will likely have to extend Z and C more than they can. Don't forget to correct the B depower limit too. If you use the kite in light wind it would be worth extending that well beyond standard. I wouldn't bother adjusting individual bridles unless adjusting the mains don't give you enough results. Even though a kite's bridles may be wrong by measurements they may be more correct to the design, or how you like to use the kite. Restoring them to spec may end in a kite you like less.

Post your measurements if you want a more in depth analysis.
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Re: Bridle Shrinkage

Postby hayes » Mon Mar 16, 2020 4:21 am

Yep shrinking is standard, I’ve had two Speed 3 and a speed 5, all the same
I remember the first time I measured and then restretched and measured again I had around 10mm shrinkage across the centre, all the way up to 50-60mm on the Z lines at the tips, didn’t know how it even flow like that haha

Replace your SPL and do a full bridle restretch if you have the patience, I do it once a year or so on mine and they fly amazingly well afterwards, like a new kite!
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Re: Bridle Shrinkage

Postby Breze » Mon Mar 16, 2020 3:48 pm

With your Soul you should do the long mixer test, not the short one. Here explains Armin the lmt at 9.26 Min
I did it now with a 10m Soul, 1 year old, i had to move C for 1cm.
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JakeFarley
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Re: Bridle Shrinkage

Postby JakeFarley » Tue Mar 17, 2020 12:22 am

:thumb: Thanks for all the information. I will do the long mixer test and possibly a full bridle stretch.

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Re: Bridle Shrinkage

Postby Adventure Logs » Tue Mar 17, 2020 1:16 am

hayes wrote:
Mon Mar 16, 2020 4:21 am
Replace your SPL and do a full bridle restretch if you have the patience, I do it once a year or so on mine and they fly amazingly well afterwards, like a new kite!
What’s your method for the bridle restretch.

Only thing annoying about the long mixer test is you need someone to help you.

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Re: Bridle Shrinkage

Postby tkaraszewski » Tue Mar 17, 2020 1:29 am

Since this thread came up, I'm gonna post two pics with a little explanation. I think I know what's going on, but I'd like some confirmation.

Ok, so I did the long mixer test on my 10m Soul. to get the A and Z lines even at the black mark on the kite, I needed to offset the front and rear lines by 2-3cm (1-1.5 inches) on each side. You can see this in the following photos. The extra gray line is tied around a piece of furniture. I was doing this by myself so used the rope to hold the lines such that A and Z lined up at the kite:

Image

Image

So, you can see that with A and Z lined up at the kite, the steering lines are shorter than the flying lines.

I adjusted the B and C lines to be even with A and Z based on the offset seen in the photos. I think this just means that I can now oversheet the kite by a little bit, but everything should be tuned correctly if I pull on an inch or so of trim, correct?

There's no other tuning to be done here, the kite should be tuned correctly, albeit with slightly short steering lines?

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Re: Bridle Shrinkage

Postby kiteykitekite » 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.

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Re: Bridle Shrinkage

Postby merl » Tue Mar 17, 2020 9:04 am

I remember doing a longish writeup of how to do the long mixer test on the old foilzone site. Shame it didn't get archived. I seem to remember he trick to make it easier to do solo was to make marks on the a main - maybe I can find a copy of my guide somewhere.

I never contributed anything of substance to the bridle tinkerers, but I did invent the term "long mixer test" (not the test, just the name). :idea: :D

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Re: Bridle Shrinkage

Postby Tomlutz » Tue Mar 17, 2020 10:19 am

Adventure Logs wrote:
Tue Mar 17, 2020 1:16 am

...

Only thing annoying about the long mixer test is you need someone to help you.
I just did the long mixer test on a Soul 12 after 1 1/2 years without help. Had to lengthen C line on the right by 3 cm, on the left side it was nearly fine. I attached the front and rear lines to two pins of a garden fence, maybe 30 cm apart. By moving to the left / right I was able to align A and Z. Just like Armin did in his video. Then I compared C and noticed it was 3 cm too short.
Last edited by Tomlutz on Tue Mar 17, 2020 10:22 am, edited 1 time in total.
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