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F1 Diablo Camber adjustment

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holden
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Re: F1 Diablo Camber adjustment

Postby holden » Mon May 23, 2016 1:19 pm

yeah, please delete the quote of the old version of my post because the 1.75 should be 3.

holden
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Re: F1 Diablo Camber adjustment

Postby holden » Mon May 23, 2016 1:28 pm

ok then, with the wac engaged, the 4:2:1 mixer becomes a 3:1:0 mixer.

foilholio
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Re: F1 Diablo Camber adjustment

Postby foilholio » Mon May 23, 2016 2:35 pm

I deleted it. You even made me question if I had it right your original calculation was so different . I was like wwwwhhhhaaat??//?? LOL

holden
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Re: F1 Diablo Camber adjustment

Postby holden » Tue May 24, 2016 10:20 am

now my head is spinning...

in my calculations the diablomixer changes from a 4:2:1 into a 6:3:1
assuming that when the diablo line kicks in, the Z line between the diablo line knot and the diablo pulley goes slack, Z will move 1.5 times the ammount of the back line movement. there is no indication for me yet that any other part of the mixer will go slack.

i have reports from a friend who did a lot of testing lately that no kite featuring the diablo line had issues concerning reverse launch and landing.

the next step in my calculations will be to get a feeling of how the trim will change with the mixer ratios changing.

h.

Regis-de-giens
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Re: F1 Diablo Camber adjustment

Postby Regis-de-giens » Tue May 24, 2016 11:09 am

I just catch the topic. Once I will have tried and well know my Elf, I should try the diablo set-up, nice reviews. Let me try to give my two cents on the theoretical approach of WAC and Diablo. Sorry for the long developpement ... but conclusion for impatients are in bolt at the end :-?

Ratios: (Notation reference: Z:C:B:A)
If you look at the three speed system (SS) mounting, you can find that :
- for standard SS = 4:2:1:0 this means that when you sheet-in Z of 4 (wrt A=0), you get 2 on C and 1 on B, I think it is the "standard" notation that we all use in France Holden) ; ok we are inline on this
- for WAC SS = "3:1:0:0" ; but requires to pull 33% more stroke on the bar to get the same Change in Angle Of Attack (AoA) to compensate for A is also moving with B
- for Diablo = "6:2:1:0" ; and you need to pull -50% less stroke on the bar to get similar change of AoA (hence the efficiency on turn)

I put WAC and diablo values into " " because it is only when the line engages, so only at the end of the depower stroke, not constant ratios, so we need to be carreful; the first part of the stroke remains 4:2:1:0 for all SS of course.

Then the choice of SS depends on your objectives, e.g:
- looking for more bar pressure
- looking for more depower with same stroke
- looking for smaller radius in turns
- looking for minimize the L/D ratio loss when you sheet-in

Indeed, on top of bar pressure and agility changes , the next serious consequence is that it changes the camber. And here is my point : we need to compare to the standard camber to understand the impact.

So if we put all ratios at the same scale (say pulling 12cm on the Z), we get:
- standard : 12:6:3:0
- WAC : "12:4:0:0"
- diablo : "12:4:2:0"

Normally the philosophy of standard SS is to keep a constant camber (can be a bit different depending on bridle location on each kite, but that is the "average" philosophy ) ; so assuming that Standard SS leads to almost constant camber, now if we compare to Standard SS (we deduce each values with the Standard SS) we get :
- standard : 0:0:0:0 (normal , this is the reference)
- WAC : "0:+2:+3:0"
- diablo : "0:+2:+1:0"

In term of camber, this means that for a 12cm stroke on Z, both SS have more camber with:
- Wac : C=+2cm ; B=+3cm
which is not very homogenous in term of profile efficiency (at least L/D ratio, but once again that may not be your objective)
- Diablo : C=+2cm ; B=+1cm which is more homogenous in term of profile efficiency and often used to get more lift on a foil kite(*)

(*) For that reason I would theoretically prefer Diablo concept to keep a good kite profile. A15 could be an exception as Foilholio described that B lines were almost at the middle of the kite, so in that case WAC could remain homogenous in that particular case, hence still an option.

When changing cambers to optimize the foilkite for certain wind conditions or practice, it is common to change B and C in the range of + 2-4 cm but not far more; hence I would bet that to keep the kite flying well when fully sheeted-in, you need to engage the diablo line in the last 20-25 cm of your bar stroke (pure theoetical guess to be confirmed, the sooner you engage the line, the more it will change the behavior of course).

Lastly, regarding bar pressure : WAC should lead to almost +50% of bar pressure ; Diablo should lead to a very light bar pressure increase of 5-10%. Keep also in mind that for a similar bar stroke, WAC has -25 % less efficiency on AoA while Diablo is 50 % more efficient (hence twice more efficient than WAC on AoA change).

In a nutshell, I would then conclude:
- chosing the diablo for race, turning ability and depower on shorter stroke, with a good boosting power with homogenous profile when sheeting-in; bar pressure is a bit higher.
- choosing the WAC for kites that have a B briddle connection line near the middle of the kite like A15, or if main objective is to increase much the bar pressure (Flysurfer uses this WAC line for this purpose mainly); but the kite could be less stable and less rapid in the window when sheeted-in.
- engaging the line at about 20/25 cm before the end of bar stroke should be a good starter theoretically
Last edited by Regis-de-giens on Tue May 24, 2016 3:41 pm, edited 2 times in total.

holden
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Re: F1 Diablo Camber adjustment

Postby holden » Tue May 24, 2016 11:23 am

thanks for your input, Regis-de-giens. the diablo mixer in fact changes into a 6:2:1:0, you are right.

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Re: F1 Diablo Camber adjustment

Postby foilholio » Tue May 24, 2016 11:28 am

Arrgg typing this while regis replied!!

I thought it should be at best 6:2:1, 6:3:1 is worse and not possible because C must be in a ratio of 2 to 1 with B , so 6:3:1.5 is more correct but not 6:3:1. I look at it being 6:2:1 because although a pulley between C and Z should be able to pull Z at 8 to 2 C, the difference between Z and C occurs at 4 to 2 so only 2 is left over to increase Z to 6. The problem is at some point Z starts pulling back on C and B, then the rate at which Z is pulled stops or reduces and the rate at which C and B gets pulled increases. So 6:2:1 becomes 5:3:1.5 or 4:4:2 or anything in between.

Which kites was your friend trying it on? I think the negative effects may not be as apparent based on wind strength and how it is setup. How are you all setting it up?

holden
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Re: F1 Diablo Camber adjustment

Postby holden » Tue May 24, 2016 11:38 am

he tested diablo 10 and 15, joker6 9 and 11 and chrono2 15 which he modified himself.

h.

foilholio
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Re: F1 Diablo Camber adjustment

Postby foilholio » Tue May 24, 2016 1:11 pm

Regis-de-giens wrote:Normally the philosophy of standard SS is to keep a constant camber (can be a bit different depending on bridle location on each kite, but that is the "average" philosophy ) ; so assuming that Standard SS leads to almost constant camber, now if we compare to Standard SS (we deduce each values with the Standard SS) we get :
- standard : 0:0:0:0 (normal , this is the reference)
- WAC : "0:-2:-3:0"
- diablo : "12:-2:-1:0"
Don't mean diablo : "0:-2:-1:0" not "12:-2:-1:0". I think you should use the terms + for things that are closer to the kite.
Regis-de-giens wrote: In term of camber, this means that for a 12cm stroke on Z, both SS have more camber with:
- Wac : C=-2cm ; B=-3cm
which is not very homogenous in term of profile efficiency (at least L/D ratio, but once again that may not be your objective)
- Diablo : C=-2cm ; B=-1cm which is more homogenous in term of profile efficiency and often used to get more lift on a foil kite(*)
I think you are making some assumptions about what is the best profile. Some CFD would be needed to tell us that but I will give you the basics. From the point of highest or best L/D, you want flat or a bit of negative camber. For most lift you want as much curve as you are going to get or high camber, so in that regard WAC is superior to Diablo line because B is held longer/looser. The problem with a standard mixer is if it is set for a flat profile it can not transition to a high camber(without stalling) and if it is set for high camber it can not achieve a flat profile. There is distinct advantages to each profile and the addition of either of these mods allows them to be accessed but differently. The main advantage to a flat profile is to be lightly powered and fast flying, it allows efficient flight. This would be when you are riding and going fast or sineing the kite to go upwind. The main advantage of higher camber is when the flight speed is low and lift is hard to generate, like trying to get up on the board or landing a jump or heading downwind. It also has the curious effect of lowering the stall speed, which allows the kite to fly in even less wind. The exact shape of the camber is perhaps not so important for this lift at low speeds, but for relaunch maybe. The camber shape of the WAC relaunches much better than the standard mixer and of course diablo line which is worse.
Regis-de-giens wrote: When changing cambers to optimize the foilkite for certain wind conditions or practice, it is common to change B and C in the range of 2-4 cm but not far more; hence I would bet that to keep the kite flying well when fully sheeted-in, you need to engage the diablo line in the last 20-25 cm of your bar stroke (pure theoetical guess to be confirmed, the sooner you engage the line, the more it will change the behavior of course).
The engagement point should be set for when you want the profile to change. Interestingly this is good at all even ABCZ on flysurfers. The all even point is also where flysurfer recommends sheeting the bar in should stop to prevent backstall. I had been wondering how flysurfer set this point, I guess it must probably be in relation to stall. So in that regard you could notice at what point the bar sheeted in stalls the kite, or for any other point for that matter, and from there you could work out the mixer state at that bar point and set the WAC/diablo line to engage at or before it. Some where near the stall point is actually I think a good place for these to engage as it lowers the stall, further extending the bar throw before stall.
Regis-de-giens wrote:Lastly, regarding bar pressure : WAC should lead to almost +100% of bar pressure ; Diablo should lead to a very light bar pressure increase of 5-10%. Keep also in mind that for a similar bar stroke, WAC has -25 % less efficiency on AoA while Diablo is 50 % more efficient (hence twice more efficient than WAC on AoA change).
This is COMPLETELY incorrect. I tell you from experience they are much the same but maybe WAC is lighter. WAC exposes B pulley to the load of A. Only 1/4 of the force on B makes it to the bar. There is of course the increased force on B ,C and particularly Z as the COL(center of lift) moves back and increase far beyond what the standard mixer can muster. This is of course the exact problem the diablo line will have but in a way worse. I will say quickly, a kite like the A15 is uniquely able to handle these forces better as the supported area between A and B is much wider and so cover much more COL change, C is also further back , and because it carries force to the bar at 1/2 offers even more protection. Z is of course 1 to 1.

The problem the Diablo line faces is the Z is at 150%, and eventually C gets at 100% instead of 50% and B 50% instead of 25%. Now depending where and how much lift there is will depend on what the bar increases.

For an example lets say the lift or force is 100 and at the center of the kite, which I would think likely for a bar position where the flight is about to reverse.

Standard bridle setup would see them about evenly spaced B at 1/3 and C at 1/3. Lets assume 60% of the lift is over B and C even with the remaining 40% on A and Z even. So A has 20 B 30 C 30 Z 20. Standard mixer exposes you to A0 B 7.5 C 15 and Z 20, so 42.5 at the bar. WAC A and B 12.5, C15 and Z 20, so 47.5 at the bar. Diablo line best A0 B7.5 C15 Z30, so 52.5. Diablo worst A0 B15 C30 Z20, so 65. Hmmm.

Now suppose the force positions are wrong and lets make A40 B40 B15 Z5, standard mixer bar is 22.5, WAC 32.5, diablo best 25, diablo worst 40. I think something like A20 B40 C30 Z10 is more realistic, giving standard mixer bar, 30, WAC 35, diablo best 35, diablo worst 60. Which leaves the diablo best and WAC the same which is about what I felt.
Regis-de-giens wrote:In a nutshell, I would then conclude:
- chosing the diablo for race, turning ability and depower on shorter stroke, with a good boosting power with homogenous profile when sheeting-in; bar pressure is a bit higher.
- choosing the WAC for kites that have a B briddle connection line near the middle of the kite like A15, or if main objective is to increase much the bar pressure (Flysurfer uses this WAC line for this purpose mainly); but the kite could be less stable and less rapid in the window when sheeted-in.
I think WAC has a better profile and tighter turn, but turning is not so important for racing and also their bars have plenty of trim to tolerate WAC.

The A15 design is more suited to the diablo line than other kites as well.... Well it is in my head as I have never tested it, but the C and Z attachments being far back will work better " I believe" :-).

There is one fundamental thing you missed from your analysis , the diablo is only 6:2:1:0 at best, roughly 4:4:2:0 at worst , and I have witnessed something like this from using it. The WAC cambers more than it and never changes ratio once engaged.

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Re: F1 Diablo Camber adjustment

Postby foilholio » Tue May 24, 2016 1:13 pm

holden wrote:he tested diablo 10 and 15, joker6 9 and 11 and chrono2 15 which he modified himself.

h.

I am just wondering how long the Diablo line is. I wonder what effect stoppers could have on relaunch/reverse, so are you friends setups reaching some sort of limit?


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