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Why have most brands settled on 4:2:1 mixers over 6:2:1?

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gwicke
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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby gwicke » Wed Nov 09, 2016 9:02 pm

> I would consider modding to a 3:1 in C for a kite that had a high tendency to go from unstable to backstall, e.g. some of the smaller race kites?

6:2:1 should actually help more to combine stability when depowered (B tight relative to A-C) with avoiding backstall when sheeted in (B loose / cambered relative to A-C). I'm currently playing with 6:2:1 on an 8m Pansh Aurora, mostly to squeeze more power out of it without affecting stability. Some other brands have used 6:2:1 on their smallest sizes only.

To me, 6:3:1 seems inferior to 4:2:1 with Diablo (4:2:0.66 when engaged):

- Slower steering and depower across the entire wind range.
- Same camber changes as 4:2:1 with Diablo. In particular, no substantial camber changes along A-B-C across sheeting range.

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby foilholio » Fri Nov 11, 2016 12:48 am

Ok first you need to speak the same language as ratios don't become fractions like that and 2 you should avoid using decimals with them.

viewtopic.php?f=197&t=2390597&p=930780

421 with wac is 310 or 620
421 with diablo is 621 or less
421 with both is 510 or 10:2:0 or less
631 with wac is 520
631 with diablo is 931 or less
631 with both is 820 or 410 or less

Strangely 421 works better with wac and diablo line, unless I made a mistake.

A 2 pulley 3:1 on C is an interesting idea. Would become 621

621 with wac is 510
621 with diablo is 921 or less
621 with both is 810 or less

If you really want to pull Z that does it. Surprised no one has tried it before. Seems obvious now to move the 3:1 ratio pulley setup to C and then you get the benefit on both C and B.

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby gwicke » Fri Nov 11, 2016 2:09 am

I believe the ratio I specified is consistent as a short form of "fraction of movement of bar movement". 6:2:0.66 means that for one unit of bar movement, B moves 1/6, C moves 1/2, and Z moves 1/0.66 = 1.5. Perhaps more clearly, you could also write it as 1/6 : 1/2 : 3/2.

To me, specifying ratios relative to Z movement rather than the bar movement / brake line is confusing, and doesn't uniquely identify a specific mixer's ratios. For example, in 4:2:1 with Diablo line engaged B and C end up having the same relative movement to Z as 6:3:1 without Diablo, but they do move differently relative to the bar / brake line. It is also a very different mixer layout.

Another issue with these notations is that we typically leave out A (as it is normally not moving), but with the WAC line engaged this is not actually true. So, once the WAC line engages, 0 : 1/4 : 1/2 : 1 (aka 4:2:1) becomes 1/4 : 1/4 : 1/2 : 1.

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby PugetSoundKiter » Fri Nov 11, 2016 7:44 am

jakemoore wrote:I'm not sure there is a convention? I think of it in terms of fraction of bar travel for a mixer gallery, B,C,Z
4:2:1 I think of Psycho 4 - 1/4 A : 1/2 B : 1/1 A Most of the speed 1 mods were done this way.
6:2:1 I think of Speed 2. - 1/6 B : 1/2 C : 1/1 A
6:3:1 I think of my mod for Speed 1 which differed from most other mods and kites. IMO the gallery spacing worked better with a 3:1 pully between C and Z with that Speed 1.
gwicke wrote:I believe the ratio I specified is consistent as a short form of "fraction of movement of bar movement". 6:2:0.66 means that for one unit of bar movement, B moves 1/6, C moves 1/2, and Z moves 1/0.66 = 1.5. Perhaps more clearly, you could also write it as 1/6 : 1/2 : 3/2…
I’ve got a 10m Speed 1 with 6:3:1 mod and it depowers enough, but I don’t have a before mod reference point. I talked to a guy who has 17m Speed 1 with a 4:2:1 mod and WAC line limiters between the A's and B's to limit overfly. He said it feels like 60% depower, similar to his Pulse and Psycho 3, with some loss in the low end. He also said the original 17m Speed 1 was overpowering him at10 knots, and by then he felt like he was managing a huge fixed bridle kite.

Liked the diagrams jakemore, helps visualize differences. I had to draw out each to see the force/distance differences viewtopic.php?p=922751#p922751 and what to change.

Speed1
Image
Speed2
Image
Speed3
Image
Image

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby foilholio » Fri Nov 11, 2016 1:40 pm

OMG I have explained all this before.
gwicke wrote:I believe the ratio I specified is consistent as a short form of "fraction of movement of bar movement". 6:2:0.66 means that for one unit of bar movement, B moves 1/6, C moves 1/2, and Z moves 1/0.66 = 1.5. Perhaps more clearly, you could also write it as 1/6 : 1/2 : 3/2.
Why throw fractions in when you already have a ratio?
gwicke wrote:To me, specifying ratios relative to Z movement rather than the bar movement / brake line is confusing , and doesn't uniquely identify a specific mixer's ratios.
Firstly it is not specified to bar movement or the brake line nor is it specified to Z. It is the ratio of Z to C to B which is the "specific mixer ratio" :roll:

gwicke wrote: For example, in 4:2:1 with Diablo line engaged B and C end up having the same relative movement to Z as 6:3:1 without Diablo


Only if you use your bizarre ratios become fractions.
gwicke wrote: Another issue with these notations is that we typically leave out A (as it is normally not moving), but with the WAC line engaged this is not actually true. So, once the WAC line engages, 0 : 1/4 : 1/2 : 1 (aka 4:2:1) becomes 1/4 : 1/4 : 1/2 : 1.
B becomes 0 the same as A. If you really want your ratio as say 1/4 : 1/2 : 1 you should simplify it to 1:2:4. OMG. Writing it as 4:2:1 and expecting people to automatically assume they all fractions of 1 is just totally wack and you won't find anyone anywhere who uses ratios like that.

anyway try this
https://www.mathsisfun.com/numbers/ratio.html

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby gwicke » Fri Nov 11, 2016 5:09 pm

foilholio, I maintain my point that sticking with a conventional definition of mixer output changes (A, B, C, Z movement) relative to mixer input (movement between front & back line) remains more useful and less confusing, and captures substantial differences in behavior between different mixers that other definitions do not.

I think the alternate definition in terms of the Z output came up when the Diablo line changed the Z output ratio from 1 to 3/2. The short form notation (4:2:1 for 1/4 : 1/2 : 1) became awkward at that point, which prompted the effort to re-scale the ratios to avoid a fractional Z output ratio.

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby jakemoore » Fri Nov 11, 2016 6:06 pm

Maybe more people in the world speak Chinese and Spanish but no sense telling kite forum people they should change their ways. I think most of the people who did the Speed 1 mods talked about the mixers in terms of fraction of movement relative to the bar.

E.G. 6:2:1 means
A moves 0
B moves 1/6
C moves 1/2
Z moves 1/1

I wish that thread from foil zone could be resurrected. The most important thing is to realize that people might have different lingo so not to be surprised in modding a kite.

Even more relevant is the chord wise position of the bridle inserts. I had a picture once on foil zone of a prototype kite. It had many bridle inserts along the chord. The designer optimized the inserts so the airfoil and camber change is optimized for the mixer.

People who are kite-experts have wind tunnels. Who knows what language they speak? They don't appear to share their secrets in the public domain.

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby jakemoore » Fri Nov 11, 2016 7:31 pm

This is cool:


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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby foilholio » Sat Nov 12, 2016 2:22 pm

gwicke wrote:foilholio, I maintain my point that sticking with a conventional definition of mixer output changes (A, B, C, Z movement)
This is not to do with mixer output per say but the ratios hence the use of :::

"A" has never been used in mixer ratios because it doesn't change.
gwicke wrote:relative to mixer input (movement between front & back line)
nor have front or back lines been represented in mixer ratios, though you are welcome to.
gwicke wrote:remains more useful and less confusing
What is confusing is to redefine how RATIOs are written as you are doing. If a person understands ratios, which are quite simple, then finds people discussing mixers, which also are quite simple, but are being talked about with a unique definition of ratios then well a simple subject becomes unnecessarily difficult.
gwicke wrote: and captures substantial differences in behavior between different mixers that other definitions do not.
this makes no sense.
gwicke wrote:I think the alternate definition in terms of the Z output came up when the Diablo line changed the Z output ratio from 1 to 3/2
No there is no alternate method other than your misunderstanding.
gwicke wrote: The short form notation (4:2:1 for 1/4 : 1/2 : 1)
This is not how you write a ratio. 4:2:1 does not equal 1/4:1/2:1 if it is 1/4B:1/2C:Z1. 1/4B:1/2C:Z1 could equal 0.25B:0.5C:1Z or 1B:2C:4Z or 4Z:2C:1B or 16Z:8C:4B. 4 does not equal 1/4 ok?
gwicke wrote:became awkward at that point
??? the only awkward thing is why a couple here can't understand how ratios are written!
gwicke wrote: which prompted the effort to re-scale the ratios to avoid a fractional Z output ratio.
Again you don't understand how ratios are written and I am not sure why I am explaining this over and over as it is basic basic math. You don't need a faction or decimals in ratios though you can, you don't even need a 1.
jakemoore wrote:Maybe more people in the world speak Chinese and Spanish but no sense telling kite forum people they should change their ways.
This is math the most universal language in the universe. If in some other "language" A=4 and B=1/4 A still does not =B.
jakemoore wrote:I think most of the people who did the Speed 1 mods talked about the mixers in terms of fraction of movement relative to the bar.

E.G. 6:2:1 means
A moves 0
B moves 1/6
C moves 1/2
Z moves 1/1
Congratulations you may or may not have had a unique use of RATIOs that no one except your tiny little corner on the web talking about a tiny little corner of a tiny little sport understood! Now for the good of helping people better understand "mixers" do you think it is wise to continue abusing how RATIOs are written?

I will say I think that use of a ratios had been used on foilzone but the correct use had been too! Bit confusing for some!
jakemoore wrote:Even more relevant is the chord wise position of the bridle inserts. I had a picture once on foil zone of a prototype kite. It had many bridle inserts along the chord. The designer optimized the inserts so the airfoil and camber change is optimized for the mixer.
There is more to this than matching a mixer to a kite. Mixers seem to work well with many bridle positions but the bridle positions themselves have a huge effect on the kite particularly like on the P4 where the A positions move forward on the tip areas to help allow the tips "collapse" into their C shape.
jakemoore wrote:People who are kite-experts have wind tunnels. Who knows what language they speak? They don't appear to share their secrets in the public domain.
People who are interested in aerodynamics have wind tunnels. Kite-experts spend a life time fiddling with kites like Peter Lynn did. People who call themselves kite-experts are pretentious twits. Aerodynamic experts are people that spend a lifetime fiddling with wind tunnels and the alike. Apparently you don't need to be a aerodynamic expert nor even grasp the basics if you want to design kites professionally, :lol: ,in fact I think it may even hinder your chances in getting the job!

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Re: Why have most brands settled on 4:2:1 mixers over 6:2:1?

Postby jakemoore » Sat Nov 12, 2016 8:47 pm

foilholio wrote: jakemoore wrote:
The designer optimized the inserts so the airfoil and camber change is optimized for the mixer.


There is more to this than matching a mixer to a kite. Mixers seem to work well with many bridle positions but the bridle positions themselves have a huge effect on the kite particularly like on the P4 where the A positions move forward on the tip areas to help allow the tips "collapse" into their C shape.
More like matching the kite to the mixer it seems to me.


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