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Speed system / mixer test explanations

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Regis-de-giens
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Speed system / mixer test explanations

Postby Regis-de-giens » Fri Mar 09, 2018 2:09 pm

As most foilkiter know, foilkites allow to change / adapt / correct the camber profile of the kite by playing with the speed system ; you can play on either various main briddles (A, B, C or Z) to do so . I drawn some illustration to show the various impacts of main possible modification as follows :

Extend A: => decrease cambre profile but not homogenous
Image

Shorten Z: => increase cambre profile and homogenous (similar as C and 1/2 B modification like Flysurfer C changing)
Image

Shorten A: => increase cambre profile but not homogenous
Image


Shorten SPL C: => decrease cambre profile and homogenous (similar as C and 1/2 B modification like Flysurfer C changing)
Image

Extend SPL C: => increase cambre profile and homogenous (similar as C and 1/2 B modification like Flysurfer C changing)
Image

I also try to show that you need to bring A and Z back to same elevation (using the trim or bar sheeting) to be able to compare the camber profiles.

To gain power for low end I recommend Case 5 (Extend SPL C) or Case 2 (Shorten Z + trim the clamcleat a bit)
To avoid frontstall instabilities I recommend to use case 4 (shorten SPL C) or "reverse Case 2" (=extend Z and untrim the clamcleat a bit );

Took me some hours but I hope this is understandable (and useful for some of you) .
Last edited by Regis-de-giens on Wed Mar 14, 2018 2:25 pm, edited 2 times in total.
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Re: Speed system / mixer test explanations

Postby Mossy 757 » Fri Mar 09, 2018 4:14 pm

:prayer: :pray: DUDE! AWESOME!

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Re: Speed system / mixer test explanations

Postby flying grandpa » Fri Mar 09, 2018 11:59 pm

I usually shorten front line lengh to adapt my 18m Pulsion to marginal winds, and make them longer for stronger winds. IMO it helps the kite to stay in the air at 3-6 knots, and increase a bit upper range.
I suspect we can gain the same or better effect by changing the distances AB;BC;CZ.
If AB=BC=(CZ)/2 then, pulling the bar, does not change the profile.
If AB<BC<CZ then thy profile change each time you pull the bar.
Takes some math and aerodynamic to get the proper change, ie bar pull will flatten the profile automatically.

I suspect Hyper Link is done with this principle in mind, so its range is awesome.
Tadeusz

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Re: Speed system / mixer test explanations

Postby oldkiter » Sat Mar 10, 2018 1:59 am

DOUBLE DUDE!! DOUBLE AWESOME!!

Great diagrams!!

Very understandable....I think!

Apparently working with Z and cleat trimming can make significant changes in camber on foil kites.

Shorten Z and trim to add camber (add low wind power ... and minimize backstall?).

Lengthen Z and "untrim" to take away/flatten camber (stop frontstall).

Thanks.

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Re: Speed system / mixer test explanations

Postby edt » Sat Mar 10, 2018 2:20 am

Nice. so that makes the camber change, that is how thick the wing is if you look at it from the side. But what if you want to have a more C-like shape, and a less flat kite. Or a more flat kite, either way. Do you have to adjust all the bridles or is there some trick where you can just adjust one or two bridles and maybe the mixer?

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Re: Speed system / mixer test explanations

Postby TomW » Sat Mar 10, 2018 11:55 am

Very helpful! I'm not knowledgeable about this at all, but want to learn.

Case 2 is shorten Z and pull in trim on depower cleat?
What kind of dimensions are we talking about mm? Or cm?

And what are " front stall instabilities "?

And do these mods apply to all foil kites with a mixer?

Regis-de-giens
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Re: Speed system / mixer test explanations

Postby Regis-de-giens » Sat Mar 10, 2018 1:43 pm

thanks guys
flying grandpa wrote:
Fri Mar 09, 2018 11:59 pm
I usually shorten front line lengh to adapt my 18m Pulsion to marginal winds, and make them longer for stronger winds. IMO it helps the kite to stay in the air at 3-6 knots, and increase a bit upper range.
On the pulsion it is a bit different because the SPL B is attached below the variable part of A . Therefore it also changes the B automatically and you are in the same cambre change that case 2-3-5 with is far better that just A of case1. I'll make a drawing next week.Nice idea from its designer by the way...

maybe i'll also make a separate table to show the impacts of these modifications on the flight, wind range and stabilities.

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Re: Speed system / mixer test explanations

Postby foilholio » Sat Mar 10, 2018 2:34 pm

Adjusting Z is the easiest way to change camber. Z shorter = more camber = more lift = more power and kite flies in less wind but more drag so harder to go upwind and the kite is less stable.

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Re: Speed system / mixer test explanations

Postby Kykeon » Sat Mar 10, 2018 7:59 pm

Regis, many thanks for the post!
It's so useful that I made it pdf and I stored it in myKitesurf_info folder!
foilholio wrote:
Sat Mar 10, 2018 2:34 pm
Adjusting Z is the easiest way to change camber. Z shorter = more camber = more lift = more power and kite flies in less wind but more drag so harder to go upwind and the kite is less stable.
Why less stable? Wouldn't it sit deeper in the window and therefore less prone to front stall?

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Re: Speed system / mixer test explanations

Postby revhed » Sat Mar 10, 2018 11:11 pm

:thumb: :D 8)
THX 4 all your time to compile this!
I am sure that on my next yet to be decided ultralowind RAM AIR, I will make "ladder knot 1 cm extensions" on ALL 4 bridal rows, each side, between mixer and bridals for fast on the beach adjusts and test flights.
I did this only on my T E, Z, D, lower bridles and was easy to dial in, this after mixer tuned of course so A B C were close to perfect.
R H


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