F1 Diablo Camber adjustment

[Regis-de-giens]

I'll try my best to answer shortly.

Don't mean diablo : "0:-20" not "12:-20". I think you should use the terms + for things that are closer to the kite.

ok , 12 is a typo of course, I will correct, thanks. I will swap to "+" for B and C " closer to the kite to align with you , no worry with me.

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.

I globally agree with your analysis of camber impact, and pro/cons of higher camber; but not sure we need to detail so much here to keep in the topic. I just assume that (with or without CFD), kite manufacturer have found a "good profile" in their design; so I just compare the camber evolution of diablo and WAC wrt the original design camber (without trying to find , in this topic , the optimum, which depends a lot on wind range, board type, skills and preferences: jump, speed, light wind, tolerance to gusts, ect ... ) What is clear is that diablo and WAC will increase the camber at the end of power stroke, and WAC will "send" the B far above C, far beyond the set-up range that is recommended by flysurfer when tuning the kite. Again, this could indeed depend on the kite design, I do not know all of them.

The engagement point should be set for when you want the profile to change. Interestingly this is good at all even ABCZ on flysurfers.

This is interesting, but this also means that if engagement starts when all nodes aligned, you will then have to use the flysurfer in a higher AoA than the maximum design ; why not, but this should then be compared to an over stroke available when sheeted-out with standard Speed system, with the drawback to loose depower ability if you do not increase the trim length or your arm length or . I think the beauty of the system is if it works within the design AoA, hence engage the line "before" all ABCZ even.

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.

Stall point depends on wind as you know ... so hard to start from it, or maybe in the light wind range of the kite as it could be (for me at least) the main condition were the kite needs optimisation...

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.

I think there is just a little little bit of truth ...
back to serious, I made a typo sorry that I will correct : I find instead +50 % on WAC and still +10% on diablo ; actually the impact on bar pressure is :
- WAC : +25% of tensions on A
- diablo +50% of tension on Z.

So, all depends on tension partition between A B C and Z; and you get different results with different tensions assumptions. It is difficult to get right figures on this partition, I'll come back to this point in the next answers.
But I still think that tension in A is far more than the double of tension in Z, so WAC (+25% A) is certainly higher bar pressure than diablo (+50% Z)

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%.

I think you are wrong, otherwise that would lead to full instability of the kite, which would never have been a solution for F-one Diablo... to me Z tension is far less than others, so Diblo keeps 50% C and 25% B (so diablo ratio remains 6:2:1:0 otherwise you should not use Diablo SS at all on this kite)

Lets assume 60% of the lift is over B and C even with the remaining 40% on A and Z even.

this part I do not agree with as you understood from above

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.

I believe that A has more tension than your figures ; I personally used Z 5%, C10%, B20% and A65% (during a ride forward of course), which leads to about 20% bar pressure with standard SS, but I might be wrong, and it depends on kite design; on the other hand, if you apply the partition you propose on the standard SS, you get indeed either 42% of kite traction in the bar or 35% in your second case, which still remains too high I believe. I bet more around 20-25% on the Speed and Aurora at least.

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.

All depends what you mean by "better Profil" . For example the L/D ratio will certainly suffer ... and I have seen nowhere that an optimization of design camber could be to increase B far more than C ... On turning impact, why not it is possible I do not know (but to me Z is the dominant parameter, i.e. B and C combined)

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.

if ratio has changed, that means that there is a "balance point" of high instability, where gusts or turbulence will move drastically the camber from one position to the other... in that case this kite design is not adapted to diablo SS, but it is unthinkable that the phenomenon appears on the f-One Diablo. on which kite has it appeared ? we could imagine that it requires a race kite but I doubt at first sight.

[foilholio]

What is clear is that diablo and WAC will increase the camber at the end of power stroke, and WAC will "send" the B far above C, far beyond the set-up range that is recommended by flysurfer when tuning the kite. Again, this could indeed depend on the kite design, I do not know all of them.

I think send B above is the wrong way to look at it. B just stops moving at a certain point. It doesn't seem, feel nor look unusually, it actually looks pretty cool. If you understand how mixers work they act on B then C then finally Z. If they get the order too wrong then they can never achieve what is an even tension on the whole wing. Because of the way the WAC is used I feel B is already in a good position when it engages and doesn't need to move any more. The WAC is working at a sheeting point beyond what the maker designed, the original shape of the wing can be maintain just new features added. There is really no negatives and only benefits when setup right. There is only really one negative I can think of and that's when landing the rear lines hold quite a lot more pressure on them which can feel disconcerting. Except the kites actual pull landing and on the ground is less with the WAC because it sits flatter. I know this because I am familiar to the feel when I walk up the lines and it is less.

This is interesting, but this also means that if engagement starts when all nodes aligned, you will then have to use the flysurfer in a higher AoA than the maximum design ; why not, but this should then be compared to an over stroke available when sheeted-out with standard Speed system, with the drawback to loose depower ability if you do not increase the trim length or your arm length or . I think the beauty of the system is if it works within the design AoA, hence engage the line "before" all ABCZ even.

Yes this is much what happens. The AOA is much higher than designed, except to be more correct the camber is much higher. The whole rear of the wind lowers like flaps on an airplane. Camber changes can generate much more lift than AOA, maybe double. On a side note I think it is debatable if foils can actually change AOA at all or only camber. I think the correct answer is they can change camber much more than AOA.

Yes there is draw backs for the bar throw length , but the performance benefits are undeniable. Flysurfer really undersold this as something just to affect bar pressure.

The problem with engaging it too soon, I feel the kite designers have put a great deal of effort getting a certain wing state tuned perfectly. You go too soon and you start to interrupt this. Then the problems of higher camber become more apparent, unstable with poor L/D. Lift=Drag. High camber has lots of lift and drag. But you can tune it to get what you want so moving it a cm here or there.

Stall point depends on wind as you know ... so hard to start from it, or maybe in the light wind range of the kite as it could be (for me at least) the main condition were the kite needs optimisation...

Yes I know I was thinking about this problem. I know for certain the bar sheeting in should be all lines even and this is in relation to the stall point. I know that all lines even equals ABCZ even. So the two must be related. If it is indeed how they set the kite maybe they do it in a certain wind. There is another option though. The all even sets a predetermined AOA or maybe just any angle relation between A and Z.This if true should be pretty standard from kite to kite and would as well have a relation to the stall point. I only need to measure some bridle positions and use the line plan lengths and I can make the calculations. I will have to start when I get a chance. A few kites and some sort of pattern should emerge.

I find instead +50 % on WAC and still +10% on diablo

I have tried them back to back and they are very similar. I just went and re read my post, poor memory , WAC does have more bar pressure. What I am certain is that they were very similar. The bar is definitely more than an extra 10% for diablo and less than 50% for WAC I would say more like 30% each. It would be very easy to measure if I was testing them together again. When they engage also changes how much bar pressure increases, the earlier the more.

I think you are wrong, otherwise that would lead to full instability of the kite, which would never have been a solution for F-one Diablo... to me Z tension is far less than others, so Diblo keeps 50% C and 25% B (so diablo ratio remains 6:2:1:0 otherwise you should not use Diablo SS at all on this kite)

I may be partially wrong but I am 100% certain the ratio doesn't stay at 6:2:1:0 . It's physically impossible for the same reasons your Malabar didn't work fully. I have also observed it, I do trust my eyes sometimes The WAC achieves much more camber than the diablo line. The Z or rear balance point with the diablo line moves to between Z and C and that is why it has trouble reversing/relaunching.

I believe that A has more tension than your figures ; I personally used Z 5%, C10%, B20% and A65% (during a ride forward of course), which leads to about 20% bar pressure with standard SS, but I might be wrong, and it depends on kite design; on the other hand, if you apply the partition you propose on the standard SS, you get indeed either 42% of kite traction in the bar or 35% in your second case, which still remains too high I believe. I bet more around 20-25% on the Speed and Aurora at least.

It may do. A little reading on the subject and apparently it is a bit involved. The correct term is Center of Pressure not Lift. It sits at about 25% of the cord, but depending on the AOA and camber of the airfoil it can be in other places, even behind the wing apparently. But generally 25% is considered normal. Interesting the high cambered or AOA state will move it forward not backward... If we take 25% I think either A and B are even or B has slight more load. C is less and Z less again. This is very helpful for something else as it confirms for me B should have more tension than C , thanks regis! Any way if we use 25% cord point the last example I gave seems about right. A40 B40 B15 Z5, standard mixer bar is 22.5, WAC 32.5, diablo best 25, diablo worst 40. Which gives the diablo lighter bar than WAC , which is the same as my findings and WAC 50% more bar than standard which is what you estimated.

All depends what you mean by "better Profil" . For example the L/D ratio will certainly suffer ... and I have seen nowhere that an optimization of design camber could be to increase B far more than C ... On turning impact, why not it is possible I do not know (but to me Z is the dominant parameter, i.e. B and C combined)

The camber increase occurs after the profile with good L/D has occurred. It's function is to give more lift for things like getting up on the board in light wind. This it does very well. Whether or not it has the perfect mix of B and C is not too relevant as it works. It actually mixes BC better than the diablo line from what I can see.

if ratio has changed, that means that there is a "balance point" of high instability, where gusts or turbulence will move drastically the camber from one position to the other... in that case this kite design is not adapted to diablo SS, but it is unthinkable that the phenomenon appears on the f-One Diablo. on which kite has it appeared ? we could imagine that it requires a race kite but I doubt at first sight.

I have seen you make this argument with my mixers I was testing where B and C were floating with each other. I haven't observed this problem. And after reading about the Center of pressure I think it would stay pretty constant based on the front rear line ratio or AOA.

[Regis-de-giens]

Hope we are not boring everyone, so I make it short.

The bar is definitely more than an extra 10% for diablo and less than 50% for WAC I would say more like 30% each.

All depends on what is the tension repartition, so all depends on kite model ; which which kite model did you tested both Speed system ?

I may be partially wrong but I am 100% certain the ratio doesn't stay at 6:2:1:0

. What makes you believe that ?

It's physically impossible for the same reasons your Malabar didn't work fully. I have also observed it, I do trust my eyes sometimes

. Wahouuuuu, you mix things sorry and this argument is not (maybe unvoluntary) honest. My Malabar works well in flying conditions (concept is not so far as diablo), at least on my kite, I tested it. Before you proposed to test it with your kite I had warned you that it could affect reverse relaunch abilities, to be tested; that is what actually happend because it not adapted to work in backward direction (which leads to inverst tensions : Z becomes then higher than A); for normal forward direction of the kite, I encontered nothing unstable and as far as I remember you did not report any problem in flying condition, sorry for this necessary precision foilholio.

I have seen you make this argument with my mixers I was testing where B and C were floating with each other. I haven't observed this problem. And after reading about the Center of pressure I think it would stay pretty constant based on the front rear line ratio or AOA.

No sorry, I still can't imagine a "good" Speed System that would lead to several ratio options depending on tension evolution . Maybe with your kite and your personal SS with B and C floating, it led to no instability problem for several reasons (like one tension is dominant on the other , or you did not encounter wind turbulence when you were at the "balance" point at the transition of ratios, or the balance in your case led to very small degree of displacement of the Spare line, whatever), but I cannot imagine that Diablo works like that on the F-one kite, knowing that a race kite need to be "strong" and stiff. I would say it another way by : if we would agree that 2 possible ratios are available at a certain AoA, the means that C and Z can alternatively become shorter and longer without control of the rider (racer !) and only depending on turbulences , wind little variations and/or reasonnace... no sorry, I think that if it happens on a kite, Diablo SS is not adapted to this kite, so better swap to WAC !

[foilholio]

Hope we are not boring everyone, so I make it short.

ROFL! let them suffer!

All depends on what is the tension repartition, so all depends on kite model ; which which kite model did you tested both Speed system ?

True. The psycho4-6 and the Genesis 6.

What makes you believe that ?

You pull on the rear lines enough like when relaunching and Z stops moving in relation to C. The Kite actually becomes sort of flat and the canopy doesn't really change camber at all any more, the whole kite seems to just shift towards you as you pull on the rear lines. It makes relaunching especially in marginal wind much more difficult.

To explain it I would have to read more on the COP. It must move back with the increased AOA even though what I read said it moves forward... Of course when the kite reverses, the COP must be on the TE to create forward flight in that direction. Then you have a situation where Z is getting loaded more than C or B. So it must pull back on them, which is what I have observed. Also before this reverse point is reached the kite never reaches as high amount of camber as the WAC line, it is obvious just from looking at them. Setup to engage at the same point if both ratios stayed the same the deflection of Z should be very similar, but it is not.

. Wahouuuuu, you mix things sorry and this argument is not (maybe unvoluntary) honest. My Malabar works well in flying conditions (concept is not so far as diablo), at least on my kite, I tested it. Before you proposed to test it with your kite I had warned you that it could affect reverse relaunch abilities, to be tested; that is what actually happend because it not adapted to work in backward direction (which leads to inverst tensions : Z becomes then higher than A); for normal forward direction of the kite, I encontered nothing unstable and as far as I remember you did not report any problem in flying condition, sorry for this necessary precision foilholio.

Yes the Malabar is mostly fine in flying and so is the Diablo line... I brought it up not the attack you but because they share a similar problem. Now I have seen you described this in your own words, the problem for both is "inverse tensions". Poor Relaunch is the main negative effect of this. For more advanced flying reverse can become a problem too. Although the malabar becomes impossible to relaunch the diablo line can still, but more difficult. The malabar reaches a balance between A and Z, for the diablo line it is between B+C and Z. In the case of the diablo line the position of BC and Z would be crucial to how much of a negative this balance point is. The way I see it the further back all 3 are the less effect this will have on relaunch. So a kite that already has BCZ further back like the A15 will be uniquely more suited to the diablo line. One improvement the A15 could have though is to move Z back to the very TE. I think just looking at the bridle positions on a kite could tell whether or not the diablo is more suited to it. I think I need to test it on the A15 to confirm some of this. I am surprised with all the new A15 owners no one has... I also think some pictures of the Diablos bridle positions would be helpful.

No sorry, I still can't imagine a "good" Speed System that would lead to several ratio options depending on tension evolution . Maybe with your kite and your personal SS with B and C floating, it led to no instability problem for several reasons (like one tension is dominant on the other , or you did not encounter wind turbulence when you were at the "balance" point at the transition of ratios, or the balance in your case led to very small degree of displacement of the Spare line, whatever), but I cannot imagine that Diablo works like that on the F-one kite, knowing that a race kite need to be "strong" and stiff. I would say it another way by : if we would agree that 2 possible ratios are available at a certain AoA, the means that C and Z can alternatively become shorter and longer without control of the rider (racer !) and only depending on turbulences , wind little variations and/or reasonnace... no sorry, I think that if it happens on a kite, Diablo SS is not adapted to this kite, so better swap to WAC !

Well I haven't made my mixers work yet but I have one or two things to try that may. Stability was definitely the problem, along with the camber shape a bit. I may have missed it but I didn't really observe dynamic changes in flight once A and Z were held constant. Although I will hold the possibility open, they do seem to hold a pretty steady position even though they are "floating". As I have said I think the WAC wins, maybe on the right kite the diablo line will be much better, I will have to test the A15. There is a third option, that is to run extra lines to the kite so as to adjust the camber from the riders end. Not something I am likely to use so I am not too keen to try it yet, but in my head I think it is something racers could use. When I have the time and if no one has tried yet I will give it a go.

[Regis-de-giens]

Psycho and Genesis are quite far from more performance kite like Aurora or speed, and of course Elf and F-one . This sounds therefore as a reason of our opinion differences.
Off course when i was saying that diablo SS should keep the same ratios, it is during a "normal" ride Leading edge forward, meaning not in relaunch situation or when kite is backstalling, for which I can agree with you. We seem to be almost in line then.

Finding a "easy" way to control camber from the bar is full of hope I agree. I was told that Paraavis did do that on one of its model but have not investigated more as i find that 4 lines are "enough"

[foilholio]

Maybe the kites are different, but I would think not too much. Bridle positions I would think are the main attribute to worry about not the shape.

Normal riding is mostly the same but still a little different. I think the WAC has the edge on lift. Bar feel is quite different. Near the stall point the diablo line feels like it hits a wall becoming extremely heavy. It makes it feel like it is impossible to stall. Where as the WAC is more progressive but still heavy and hard to stall.

I think you just need to try them Regis and draw your own conclusions. Both are quite easy to install, the WAC is very easy.

The adjustable setup would use 6 lines and perform much the same as a 4 line, i.e. not like a 5 line.