F1 Diablo Camber adjustment

[foilholio]

Was watching one of the Foil cup videos and heard it mentioned the F1 Diablo has on the fly camber adjustment? I was wondering how they do this? I can think of running a separate line to A mains on a cleat. Pulling it would increase camber.

[kitexpert]

FS has used for a long time system in which speedsystem pulling ratios and A B C lines positions by the chord are designed so that when you sheet in airfoil camber increases. It is a simple system and very probably used in Diablo too.

You can think it like that: A line is fixed, it is the pivot point. Distances from A to B and C linerows are the lenghts of the lever arms. Usually B lines are pulled 1:4 and C lines 1:2 from the bar movement. With that speedsystem If C lines are positioned further back than the middle point from A lines to brake, it is pulled less than needed to keep airfoil the same. Result is increased camber, because brakes are always pulled 1:1. And same of course for the B row, if it is further back than 25% of the distance from A to brakes, camber increases when sheeting bar in.

[foilholio]

I understand how mixers work. This was described as something that could adjust the mixer while you were riding. Most mixers are set to neutral. If you lengthen BC relative to AZ you get more positive camber. Which is better for downwind riding and worse for upwind. A line to adjust A seems one solution, but maybe they are just using WAC lines to flatten the front of the wing.

[foilonfoil]

Buddy loves his F-One but his only negative comment is that the mixer is a bit of a mess. He has had it tangle itself up on the water and lose his kite.

[kitexpert]

"If you lengthen BC relative to AZ you get more positive camber."

How could this be possible during the flight? If it was, it surely would have been done already - if something like that is good idea at all.

And if you do that kind of change in advance, it distorts airfoil shape - adds drag - and depower is lost considerably. It would have been much better to design kite with higher camber airfoil in the first place, if more effective kite is needed.

But that kite would have poorer depower, stability and gust absorbing. This kind of design path leads very soon to horrible front stalls and collapses, it is just not possible for depowerable kites.

"A line to adjust A seems one solution, but maybe they are just using WAC lines to flatten the front of the wing."

I don't get what this means. A lines are fixed. If you try to shorten them by pulling the bar (via some new line, WAC ?) you just transfer load from your harness to your hands. Exactly same effect than shortening A lines is achieved by lenghtening other lines - and this is possible by pushing the bar out.

What I looked from the pictures (not very clear) of Diablo, speedsystem and linerow positions look similar compared to other racefoilkites. But if there is something different, I am very interested to see what it is.

[joriws]

On previous thread about the Diablo I understood that Diablo has additional line from backlines to C or mixer pulley of C. The additional line is only in tension close to full power. Would that change 4:2:1 mixer to 2:1 meaning

- Normal 4cm of bar pull is 4cm of Z, 2cm of C and 1cm of B.
- Close to full power 4cm of Z is 4cm of C and 2cm of B. It would add more camber.

Please correct me if I am wrong. I've never seen Diablo, only distant race pictures.

[foilholio]

I found the thread viewtopic.php?f=196&t=2389720
in it ozchrisb describes it as

"There's a line that goes from the rear pulley, down to another ring on the rear line attachment, and then onto the rear line bridle. It's adjusted so that when you pull the bar in hard it really pulls the B/C pulley and the trail edge bridles and the kite cambers up a lot. It's used downwind."

Although the description is not that clear, a picture would be great. It sounds like what you are describing joriws. I interpret it as a different way of implementing a WAC line. They are restraining the ZC relationship. Which doesn't make any sense to me. But if it works heh?

I would have thought restraining AB as in a traditional WAC would be more fruitful and even adding C to the mix. A separate line to trim A independent would produce the best positive camber or hollow profile. But it sounds like they are trying for some weird more mechanical flap like camber.

kitexpert the way a positive camber is introduced is by changing the settings on the mixer. This is something any flysurfer rider is familiar with as they have had adjustable mixers for over a decade or more. As to changing in flight the setting this will require additional line/s to the rider.

As to why you would want to change the settings. Different profiles produce different results. The depower, is not changed* by the mixer. This is "hard wired" into the kite with the positioning of the A bridle gallery, and the ballooning of the kite. Having said that it is possible to limit the depower by preventing the other galleries from going slack. Kites that do that have their reasons.

You are identifying the problems with a particular profile. Positive camber are unstable and collapse etc. But the higher the camber the higher the lift and so drag of course, would seem good for down wind no? and it is. A neutral or negative camber will be more stable better upwind. If you could have both, an advantage in something like racing could be had.

You are right A lines are fixed. With an AB WAC line the load is transferred to your hands but through B pulleys at 1/4 force. So the A mains go slack or slackish depending on the sheeting. This is a different effect. A B become fixed and only C and Z will then sheet in. This increases camber and with it lift. To be effective the WAC needs to be short, which limits depower. That and with the increased bar pressure is probably why flysurfer stopped using them. Gunnar should know he was around when it was removed.

If you were to run a line to A mains and adjust them independently. It would have the same effect as adjusting BC. This would also depower/power the kite so you would need the trim capacity to overcome it.

[kitexpert]

"kitexpert the way a positive camber is introduced is by changing the settings on the mixer."

No. At least this is not correct way to do it. There is actually just one mixer position for which kite is designed to (minimal airfoil shape distortion within bar movement). And this is chosen "all equal" just for simplicity to correct if/when pulleylines are shrinked.

It makes no sense to try to distort kite with low camber airfoil to high camber airfoil by fixed mixer setting. If higher camber is needed, it should have been chosen in the first place. Method I already discribed for changing kites camber in flight is sensible and used.

"The depower, is not changed* by the mixer. This is "hard wired" into the kite with the positioning of the A bridle gallery, and the ballooning of the kite."

Mixer (speedsystem) is a mechanism to change foilkites AoA and camber (with appropriate B and C line row positions) by moving the bar. That powers and depowers kite. A line position and ballooning have less to do with depower, ballooning (cell bulging) none as I can see.

"A neutral or negative camber will be more stable better upwind."

No. Lesser camber is for depower in low AoA's. Then its stability and low lift are needed. Higher camber means bigger L/D, so better upwind performance. It is better for downwind too, because it backstalls later.

"If you were to run a line to A mains and adjust them independently."

A lines can be trimmed "independently" in every kite. Usually clamcleat above depowerline is used. It changes kites AoA and camber exactly the same way as moving the bar, camber of course only if kite is designed to do so.

Description for Diablos system is so unclear it is hard to comment. But if C is somehow pulled as much as Z, it means Z is pulled too little relatively. Then camber in that area of the canopy decreases (does not grow) and strong "flap effect" is less used. Kites AoA gets higher anyway, which sounds reasonable for downwinders - if kite does not backstall before that.

[jakemoore]

ParaAvis VX also has two trimmers, one for AOA and one for camber. I have not seen it described well in English. Could Fone be taking a page from ParaAvis play book?

[foilholio]

Interesting Jakemoore, is this new to ParaAvis? Any pictures. ................................


AHHA! I have worked out in my head how they do it or the best/"another" solution. You separate the C pulley line at the A main connection OR you make an attachment on the front of the pulley line maybe with a stopper knot, where it wont interfere with the pulley. You will need a bridle of some sort, probable a large V. You then run a line down to a cleat. This allows you to adjust the length of the C pulley line and with it B in the correct ratio. The problem with just adjusting A or as I just had another idea before of adjusting say BC pulley lines together, is the ratios of BC will get thrown out and create a bad profile. Nice! on the fly mixer adjustments, I can see this becoming the next big thing in racing.

Kiteexpert

A depower foil needs to be able to adapt to different profiles. There are a number of reasons to choose a different profile than the mixers profile. But lets not discuss that, ozone cant have everything for free.

A bridles set the minimum AoA achievable.

Higher Lift equals higher drag. Lower lift/drag profiles give best performance. Same reason you dont see planes flying everywhere with flaps down.

A lines are not your front lines.

I think a lot of this is lost on you as you probably only ride foils without adjustable mixers (Ozone). It has been quite common for flysurfer riders to change mixer settings for different conditions. Some would even modify the mixer so the changes would be just a larks head moved here or there.