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Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

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beebopbogo
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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby beebopbogo » Tue Dec 29, 2020 10:29 am

[quote=SpunMonkey post_id=1107158 time=1597109482 user_id=85813]
[quote=kiteexpertyexpert post_id=1096793 time=1589318373 user_id=100251]
The number one way to tune any foil kite is adjust Z
[/quote]

Any tips for knowing when to shorten z and when to lengthen it?

Im looking specifically to stop wing tip tucking when going downwind. this kite has flown reasonably well and only recently started doing this downwind.

Thanks.
[/quote]

I had this exact problem on my 13m Flysurfer Sonic 2. At first, the tips would never inflate on launch wreaking panic on the beach as I try to steer with only the center foot and a half (tongue in cheek) inflated. I did a long mixer test (see below) which showed my Z was way short. So I lengthened it about 5 cm, 50 mm! which got it to fly nicely except downwind. Downwind, the tips would deflate once in a while and wouldn't reinflate unless stopped in the water and yanking the steering lines. I lengthened Z another 10 mm or so and now she flies great.

As for the long mixer test (LMT), they don't make it easy on the Sonic 2. You have to get the line plan and do some addition and comparison.
1) Add a1 + A1 + AI = a
2) Add b1 + B1 + BI = b
3) Add c1 + C1 + CI = c
4) Add br1 + BR1 + BRI = br
5) Find the differences between a and b, c, br. (a-b, a-c, a-br) and write those 3 numbers on a paper to compare to your kite.
6) Fix the bar side of the mixer (Back-Main and Front-Main lines) to a single point.
7) At the kite, pull with 5 kg of force (I used a luggage scale for accuracy) on the a1 and b1 points and compare to your notes.
8) Do the same for a1 and c1, then a1 and br1.
9) After the LMT, you can now adjust the mixer in this order: C pulley line, B pulley line, then Br line (that figure 8 knot is a b#&tch to loosen).
Or just skip all that crap and experiment with the Z line length to see if that fixes your problem.

merl
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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby merl » Wed Feb 17, 2021 3:00 pm

Just found this post as I am preparing to tweak my newly acquired sonic2 13. I have a small observation/correction for those who find this thread wanting to do a retune, and a question.
beebopbogo wrote:
Tue Dec 29, 2020 10:29 am

I had this exact problem on my 13m Flysurfer Sonic 2. At first, the tips would never inflate on launch wreaking panic on the beach as I try to steer with only the center foot and a half (tongue in cheek) inflated. I did a long mixer test (see below) which showed my Z was way short. So I lengthened it about 5 cm, 50 mm! which got it to fly nicely except downwind. Downwind, the tips would deflate once in a while and wouldn't reinflate unless stopped in the water and yanking the steering lines. I lengthened Z another 10 mm or so and now she flies great.

As for the long mixer test (LMT), they don't make it easy on the Sonic 2. You have to get the line plan and do some addition and comparison.
1) Add a1 + A1 + AI = a
2) Add b1 + B1 + BI = b
3) Add c1 + C1 + CI = c
4) Add br1 + BR1 + BRI = br
5) Find the differences between a and b, c, br. (a-b, a-c, a-br) and write those 3 numbers on a paper to compare to your kite.
6) Fix the bar side of the mixer (Back-Main and Front-Main lines) to a single point.
7) At the kite, pull with 5 kg of force (I used a luggage scale for accuracy) on the a1 and b1 points and compare to your notes.
8) Do the same for a1 and c1, then a1 and br1.
9) After the LMT, you can now adjust the mixer in this order: C pulley line, B pulley line, then Br line (that figure 8 knot is a b#&tch to loosen).
Or just skip all that crap and experiment with the Z line length to see if that fixes your problem.
For this particular kite (and maybe other flysurfers - I did not look at other lineplans) you need to (point 4) add br1 + BR1 + BRI + BRMain = br.
Breze wrote:
Mon Sep 07, 2020 3:13 pm
...
For the 13m Sonic2 A1 to C1 -!!! 33mm ,A1 to B1 + 10mm, A1 to Z1 + 216mm. - means A1 shorter than C1. + means A1 10mm longer than B1
Hope it helps you
I just redid these calculations from the line plan and I get the same numbers - but Z1 is longer by 216, not shorter (this includes the BRMain).

From reading the thread, the recommended major retune seems to be (i) add 2cm lcl extensions to a1 - a4 and (ii) do the long mixer test as above.
Part (i) comes from Breze's post
Breze wrote:
Tue Aug 18, 2020 6:27 pm
I had a phone call with one of the FS guys at the repair shop. Very nice guy, he gave some light to my questions.
They do long mixer on the a1 row, not a8 like the Soul.
He told me the following steps.
a1-4 gets 2cm extra LCL. Only a1-4 to give back the arc shape .
I'm a bit puzzled by this. a1-a4 are the four bridles lines which would have shrunk the least out of all the bridles as they are the ones with the greatest load. So what is the logic in making them longer? There is another post where someone fixes the problem doing the opposite - extending just the outer a bridles; that makes a lot more sense to me...

merl
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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby merl » Sat Feb 20, 2021 6:31 pm

Ok so I Added an adjustable pigtail At Z set to 1cm and did a regular mixer test to set everything equal. But then I tried the long mixer and can't quite believe the results. B 4cm too short, C 7cm short and Z 9cm (roughly- left and right are fairly different). Since the long mixer numbers I calculated were the same as Breze posted I think they must be right, but the adjustments needed seem seem crazy big - and this is all from the bridles as I already adjusted the mixer.

Can this really be right? (And if I lengthen a1 -a4 as suggested it would be even bigger)

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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby Breze » Sun Feb 21, 2021 11:23 am

For this particular kite (and maybe other flysurfers - I did not look at other lineplans) you need to (point 4) add br1 + BR1 + BRI + BRMain = br.
Breze wrote:
Mon Sep 07, 2020 3:13 pm
...
For the 13m Sonic2 A1 to C1 -!!! 33mm ,A1 to B1 + 10mm, A1 to Z1 + 216mm. - means A1 shorter than C1. + means A1 10mm longer than B1
Hope it helps you
I just redid these calculations from the line plan and I get the same numbers - but Z1 is longer by 216, not shorter (this includes the BRMain).

From reading the thread, the recommended major retune seems to be (i) add 2cm lcl extensions to a1 - a4 and (ii) do the long mixer test as above.
Part (i) comes from Breze's post
Breze wrote:
Tue Aug 18, 2020 6:27 pm
I had a phone call with one of the FS guys at the repair shop. Very nice guy, he gave some light to my questions.
They do long mixer on the a1 row, not a8 like the Soul.
He told me the following steps.
a1-4 gets 2cm extra LCL. Only a1-4 to give back the arc shape .
I'm a bit puzzled by this. a1-a4 are the four bridles lines which would have shrunk the least out of all the bridles as they are the ones with the greatest load. So what is the logic in making them longer? There is another post where someone fixes the problem doing the opposite - extending just the outer a bridles; that makes a lot more sense to me...
[/quote]

Hi Merl
Sorry for the late answer!
Some questions first for general understanding
Did you test fly the S2 13m yet? Or do you want to make a general check up of the bridle length new vs old?
What flying characteristics did it show? Frontal collapse, backstallish, tips not popping out ?

The given advise from the FS men was esp against the frontal callapse- beginning in the middle of the LE.
In this given case, the lengthened a1-a4 increases the AOA in the middle. The FS men mentioned a better, stable airflow towards the outer tips and he has good results in combination with the shorter PMAs. Yes it is counterintuitive and there are more ways to get a stable kite, he said.

For me it worked very good. The S2 is now very stable and after some more tuning the B&Z and going to only one knot shorter on the outer PMA it has the good performance back.Meantime i bought a hole new bridle but did not installed it yet.Btw the new bridles are all 7mm shorten than the given length of the lineplan, i think bc of the shortenings of the splices...

When i did the first LMTs i pulled what i thought would be 5 kg by hand. I then changed this inaccurate method to a rigg with two hanging 5kg weights with lines running through pulleys and connected with small biners to the LCLs to compare A to B,C,Z with a ruler. The front and backlines under the mixer where fixed at the same point, with A and Z mixer same position.
I had same lenght ratios as you. The original yellow sparepart lines were to short on C to further lengthen them, so i changed to new ones. There it becomes quite obvious how "off" the short mixertest is.
If you want, i can give you the B C ratios and length of the Z pigtails.( Beside every kite is a bit different when getting older, but would be a comparison)

Now i hesitate with the installation of the new bridle bc the currend set up flys good, the never change a runnung system saying comes to my mind.
But it will be interesting to see the difference in performance and i want to get rid of the lumpy spaghetti lines, producing sleeves and rat nests easily.
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merl
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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby merl » Mon Feb 22, 2021 10:58 am

Thanks Breze. No I have not tried it yet - this is the first tune up after doing some major internal repairs so I guess I should try it first. Thanks for the tip about pullys at the lcl ends - I was rigging a pully at the other end and it is hard to get equal tension on both lcls and also hard to measure!

merl
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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby merl » Thu Feb 25, 2021 11:24 pm

It flies! I equalised the mixer (short mixer test) and added a z pigtail of about 5 cm. Inflated well, no tucking or front stall (static flying only) but pulls like a truck, stalls easily and feels like it does not depower much. I guess I need to lengthen z a bit more and maybe lengthen C and B a bit?

merl
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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby merl » Thu Mar 11, 2021 11:08 am

merl wrote:
Thu Feb 25, 2021 11:24 pm
It flies! I equalised the mixer (short mixer test) and added a z pigtail of about 5 cm. Inflated well, no tucking or front stall (static flying only) but pulls like a truck, stalls easily and feels like it does not depower much. I guess I need to lengthen z a bit more and maybe lengthen C and B a bit?
Times like this when you miss foilholio - he'd insult your stupidity but always help out on a mixer question :)

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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby Breze » Thu Mar 11, 2021 3:57 pm

merl wrote:
Thu Feb 25, 2021 11:24 pm
It flies! I equalised the mixer (short mixer test) and added a z pigtail of about 5 cm. Inflated well, no tucking or front stall (static flying only) but pulls like a truck, stalls easily and feels like it does not depower much. I guess I need to lengthen z a bit more and maybe lengthen C and B a bit?
Shorter Z(pigtail with 3,5cm) and, or longer C ( B gets also 50% longer) until it gets frontal collapse, would be my way to try

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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby tsuneo » Sun Mar 14, 2021 4:19 am

merl wrote:
Thu Feb 25, 2021 11:24 pm
feels like it does not depower much.
Depower is controlled at the mixer by how far B can extend past A. Measured by standing on your front line at the mixer, then pulling A and B till they stop, then measuring the gap between them. On most FS kites this would be at standard ~25cm ( a simple calculation of 1/4 the length of the C pulley line being 100cm). When other factors like the rest of the bridles shrink are accounted for then more than 25cm is needed for full depower. In fact most FS kites are a little conservative at standard 25cm and you can go much longer to say ~30cm if you want a lot of depower particularly in the middle of the window for say wave riding.

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Re: Help re-tuning a Sonic 2, am I on the correct path? Bridle/mixer

Postby kitexpert » Sun Mar 14, 2021 12:56 pm

tsuneo wrote:
Sun Mar 14, 2021 4:19 am
merl wrote:
Thu Feb 25, 2021 11:24 pm
feels like it does not depower much.
Depower is controlled at the mixer by how far B can extend past A. Measured by standing on your front line at the mixer, then pulling A and B till they stop, then measuring the gap between them. On most FS kites this would be at standard ~25cm ( a simple calculation of 1/4 the length of the C pulley line being 100cm). When other factors like the rest of the bridles shrink are accounted for then more than 25cm is needed for full depower. In fact most FS kites are a little conservative at standard 25cm and you can go much longer to say ~30cm if you want a lot of depower particularly in the middle of the window for say wave riding.
Depower range is a kite (wing itself) related thing and you can't make assumptions of it from pulley line lengths. Bigger kite needs of course more pulley line length for same AoA range than a small kite because it has longer chord.

In practice it is not that interesting how much pulleys move as long as this movement is not restricted harmfully. FS mixer length (incl. pulley lines of course) is long enough for biggest kites of 21-23m so it should be enough.

You can't increase depower by using longer mixer because with usual mixer back lines (line rows) already start to slack when kite is fully depowered. Trying to make them even more slack doesn't help.


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