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Guy Capra (Alomphega)

How to stabilize a "FlowForm" single line kite ?

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Hello all,

I have some problems with a new bought FlowForm single line kite : it turns in the sky and falls down on the ground by itself (and yes, if you ask for that, there was wind enough for the try ;-) )

I remember some time ago I seen a tip for FlowForm tuning on the web but alas I do not find it now... Any idea where I can find this stuff ?

Thank you very much,

Guy

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This is what Dave Gomberg says about tuning, on big Foils, Sleds, etc:

Pilot Tuning?

Lines and fabric may change after a few first flights -- like a new pair of shoes settes in with wear. For simple "field tuning", I simply gather all the lines in one hand. I adjust the bottom row until the kite is flying straight. Then adjust the top to orient for lift. Then remove the slack from any other lines.

I tie a knot in all the lines, connect a flying line, and send it up to see how the adjustment worked. If correct, I just cut off all the loose bits.

Same works for SkyForms.

He specifically says about the Sutton Flowforms:

Flowforms are stable and remarkably gentle for their size. Remember to add your own drogue , spinning windsock or our exclusive Sutton Streamers.

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I have found in most of my situations that the tail or drogue or whatever you choose is just the ticket for those problems. Not always, but usually will calm the kite right down into a stable flying pattern. I have several tail lengths I use depending on wind conditions and what I am trying to accomplish in the area I am flying in.The bridle setup is a very good place to look also. :single:

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Hi,

I think you are right, but I need to not use tails (some R&D work) so I'll try the briddle setup. I think the attach points of the bridles are the first a way to look at, as well as their setup as you say.

See you later,

Guy

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Hi,

I think you are right, but I need to not use tails (some R&D work) so I'll try the briddle setup. I think the attach points of the bridles are the first a way to look at, as well as their setup as you say.

See you later,

Guy

Not sure why you are opposed to using a tail, of some type, but the earlier statement that I posted, came directly from the Gomberg website, and it was specifically directed at the FlowForm.

"Flowforms are stable and remarkably gentle for their size. Remember to add your own drogue, spinning windsock or our exclusive Sutton Streamers"

Just curious, what size FlowForm do you have ? Is is an old one ? I didn't think that the FlowForm was being made, any longer ??

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If you check the links in his signature... I think he may be tinkering some with different style sails used for purposes that suit his idea. :)

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Yes Nick and Scott, as you can see I said it is needed for some R&D personal work.

Nick, you can see the flowform I talk about there on my video (at 2'50'') :

You can see it also there :

http://youtu.be/WVNW9Qh2r3E

Please note I'm not opposed to your advice nor the Gomberg's one, just I need to not use it because I need to use a kite as simpliest one as possible because it will launched from a Stand Up Paddle on the sea.
If you want to know and see more (and follow the future works) you can watch this permanent link always on the last and actual story telling : www.velalae.info

Thanks again for your answers,

Best wishes,

Guy

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Most factory drogue will double as a storage bag ... And for the benefits may be worth the effort for a little more hassle. I saw your videos and idea . I don't think an added stability device to the rear of the foil would create too much more of an effort in launching from an S.U.P. once in the air, the performance characteristics of the foil will be drastically improved.

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Hi Scott, thanks for your interest in my R&D, but you know there are some other factors I can't yet explain, which need no tail, as for instance the auto-steering device I am working on.

That said, the tail-bag is a good idea I already tried with a power sled, and yes, it is an idea I can use in the future, when my device will work as well as I want.

Best Regards,

Guy

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Ok, now I understand what you are doing. I also see, from looking at your "kite" videos, that it's pretty evident, that the FlowForm is much more stable, "with" the tail attached. I see why you don't want a very long tail, but from what I understand, the drogue, which could be tied off short, would most likely offer even more stability to your FlowForm, than a simple streamer, or tube tail. I would have to agree with Scott, also, in that the drogue (a single drogue) could serve as a stuff sack for the sail, which if packed properly, should be simple to launch from the deck of the SUP. (Just my 2 cents) :ani_victory:

The part that I don't understand, is how you plan on incorporating "auto-steering"..............but I suppose that's a big part of the project. Keep us informed.............very interesting, and good luck.

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Many thanks for your wishes Nick,

Yes, the "auto-steering" part is the main part of this project of course.

The goal is to auto-steers mechanically the kite at 45° of the wind (upwind as well as downwind) to let the navigator just navigate without piloting the kite nor other complication.

I can't really explain in English (I apologize for my bad English) but I guess when you will see the videos it will do the job.

Best Regards,

Guy

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The goal is to auto-steers mechanically the kite at 45° of the wind (upwind as well as downwind) to let the navigator just navigate without piloting the kite nor other complication.

Being a sailor, I don't exactly understand, what you mean (?). When sailing a boat, you can sail towards the wind, but only 45 degrees to either side, and all the way around (270 degrees), from one upwind point, to the other. BUT, when flying a kite, you can only fly in the 90 degrees, directly downwind (45 degrees to either side).

Possibly, I don't clearly understand what you mean by, "45° of the wind (upwind as well as downwind)"

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Nick - 90* might be a little too limiting, but not much more than a 120* functional window, in the strongest winds! I don't see how a kite will fly "upwind" in any way, or shape! I too sailed, don't see how this can be accomplished!! :ani_giveup:

I'd like to see how this gets done!!??

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Hello,

You just understood the difficulty of inventing something new ! :ani_idea::ani_wallbash:

To be more precise : the kite does not go upwind of course. As a sailor you can understand you need a sail (for the air power) and a keel or a dagger board (for the water power) and with this 2 things you can go upwind.

In my invention the kite replace the sail and is automatically tuned and stay at 45° downwind (not 0° as all the common single line kites), that is all the stuff.

If you know sailing you can now understand how it will work, if you don't know sailing... Well, wait I will finish and with my invention you will be able to sail ! :ani_yahoo::ani_victory:

Please if you want to know more I invite you to subscribe to my nauticaerium.com webblog, I can't say anymore for now because I'm yet working on this project.
Also please stay your doubts in your own head, and wait I have published and said I have something working before to talk more about this work ! :gathering:

Best Regards,
Guy

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Nick - 90* might be a little too limiting, but not much more than a 120* functional window, in the strongest winds! I don't see how a kite will fly "upwind" in any way, or shape! I too sailed, don't see how this can be accomplished!! :ani_giveup: I'd like to see how this gets done!!??

Yes, I agree about the 90*......... it's probably a bit more than 45* to either side, in actuality, but 60* (?). That's a wide wind window, and I would think that's really pushing it to the limit of the window, for sure ! As for flying a kite upwind, I agree with you, I don't see how this can be accomplished, in any way (?) I too, would like to see this, and look forward to seeing the completion of Guy's project !

As for my "sailing" vs "kite flying" analogy (and theoretically speaking), I always like to tell newbies (especially those that have sailed), that the 90*, where you CAN NOT sail a boat (to windward), is the same 90* where you CAN fly a kite (to leeward), if you turn your back to that "same wind", that you couldn't sail in. Just my simple analogy ! :ani_victory:

You really can, find just about anything, on the Internet !

post-4670-0-72094400-1382276948_thumb.gi

The diagram above shows the kiting "Wind Window" - the pink and tan areas. These represent the area where your kite should be able to perform best. The pink area is where your kite is directly in the winds path, this area will give you the greatest amount of pull if you are flying a traction/power kite; or the best control and speed if you are flying a stunt/sport kite. The tan areas are where the kite will start to decrease in power or slow down. Turns are usually done in the Tan area as well as launching and landing your kite. The edge (grey area) of the "Wind Window" is at the end of the Tan area and is where the least amount of wind is on the kite. The exact location of the edge of the wind window will vary depending on the style of kite you are flying. Usually when a kite approaches the grey area or edge, it will begin to "luft" or "stall", causing the kite to drop out of the air. If this happens, you may have to take a couple quick steps backwards to bring your kite back into the tan area, allowing you to turn your kite and continue flying.

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It's certainly possible to tack upwind under kite power. Kite surfers do it all the time! In addition to the pull in the downwind direction, a kite also generates lift across the wind like an airplane wing. When you factor in the change in the apparent wind direction that comes from the pilot moving rapidly over the water, it can be quite complicated.

It sounds like Guy is planning a sort of kite surfing with an automatic mechanism to trim and control the sail. That would be pretty cool. As has been pointed out, these kites are inherently dynamically unstable. You can't fly them as SLKs without a drag stabilizer of some kind. But it's that very instability that makes fighter and stunt kites maneuverable. Only constant adjustment by the pilot keeps them in the air. If he can rig the flowform to be controllable (e.g. as a dual line), and his controller can sense and correct the kite fast enough, this could work.

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It's certainly possible to tack upwind under kite power. Kite surfers do it all the time! In addition to the pull in the downwind direction, a kite also generates lift across the wind like an airplane wing. When you factor in the change in the apparent wind direction that comes from the pilot moving rapidly over the water, it can be quite complicated.

It sounds like Guy is planning a sort of kite surfing with an automatic mechanism to trim and control the sail. That would be pretty cool. As has been pointed out, these kites are inherently dynamically unstable. You can't fly them as SLKs without a drag stabilizer of some kind. But it's that very instability that makes fighter and stunt kites maneuverable. Only constant adjustment by the pilot keeps them in the air. If he can rig the flowform to be controllable (e.g. as a dual line), and his controller can sense and correct the kite fast enough, this could work.

All true - I understand tacking from sailing, and I realize what is going on with kite surfing, but these sails & kites are maneuverable, via rudders, keels, and/or control lines. A "single line kite", on a single line, and a FlowForm kite at that, is not readily maneuverable. Theoretically, the SLK is going to find a downwind point, and basically that's where it will stay. In addition, as you have pointed out, this style SLK, definitely needs some sort of "drag stabilizer", in order to fly steady and reliably.

I can surely see how, with a fin (i.e. centerboard / keel), Guy may be able to maneuver a SUP out 45 - 50 degrees, possibly even 90 degrees, to either side of the downwind force (pull), but once he passes that point, and he tries to point that SUP upwind, which in this case would be opposite to his driving (pulling) force, it seems to me that either the kite is going to pull him off of the SUP, or, well, I think it's simply going to pull him off balance, and into the water. Nothing that I can visualize, is going to make a SLK kite, come around and fly with it's back to the wind, nor is it going to pull him into the wind. There will surely have to be some kind of multi-line control adapted to the kite, for this to happen, and I'm not so sure that the FlowForm, is the kite for this application. "Collapse", comes to mine.

Also, as you have mentioned, kite surfing has already been invented, is quite controllable, and tacking into the wind is done all the time, just as in sailing, but again, that sail is quite maneuverable, via the control lines. All the mystery and kinks have already been worked out. Sounds to me like Guy may be trying to "re-invent" the wheel, and adapt it to the SUP. I hope he succeeds, and I surely don't mean to doubt his theory. There is obviously much more to this endeavor, than he has shared with us. I would really like to see how this will all work, and I would love to see him perfect this idea / theory, but with what little information that we have, I still have a hard time seeing it happen, without a different kind of kite, and without one that is easily maneuverable. And if this is the case, why not use a simple two line foil, such as the small Prism Snapshot, or something similar. Even a simple dualie, rigged on short lines, and rigged to float, seems to be much more maneuverable than any kind of single line kite which pulls downwind only..............I'm perplexed, for sure. :g:

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Two thoughts come to mind when watching your video:

1) Four keels instead of three would help both the shape of the airfoil and the ability for it to maintain inflation.

2) The keels are too long from the bridle point to the leading edge. Being too long will create too large an angle of attack and contribute to the side-to-side hunting and eventual crashing.

If the kite is an experimental one, then sew a small bridle loop on the rib right at the rib-to-lower panel joint. Do that for each of the seven ribs. Then add a new bridle line from each of the loops to the junction of the three main bridle lines-to-the flying line. First adjust (tighten) the new bridle lines to flatten out the leading edge. Then slowly tighten all of the seven new bridle lines as a unit until the kite flies in a stable manner.

Too stable and it will not correct for wind gusts ... not stable enough and it will not stabilize when it's hit with gusts. There's a sweet spot that is hard to find with a single row foil kite. Jalbert's early kites had multiple rows of bridle lines that allowed him to adjust to get the best flying angle.

Foils are more of an art than a science ...

Cheers,

Tom

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Thanks a lot for your good advice Tom !
Yes, I agree the solution will be to change the AOA step by step, so I will test this.

Maybe in a first attempt I will change only points of attach as it's easier, then I will see what happens...

Best Regards,
Guy

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A "single line kite", on a single line, and a FlowForm kite at that, is not readily maneuverable.

No argument from me. By the time you modify a FlowForm enough to make it controllable, it's a very different kite. This project would seem a lot more practical if you started with a quad foil. There are already examples of automatic systems to control those, and it's where I would start. But then, I'm not a kite maker. :)

Theoretically, the SLK is going to find the downwind point, and basically that's where it will stay.  In addition, as you have pointed out, this style SLK, definitely needs some sort of "drag stabilizer", in order to fly steady and reliably. 

 

Almost. A stable, symmetrical SLK will find the downwind point and stay there. An unstable one will swoop all around it. An asymmetrical one (e.g. one deformed by extra control lines) may have a stable point that is not directly downwind.

Nothing that I can visualize, is going to make a SLK kite, come around and fly with it's back to the wind, nor is it going to pull him into the wind.

The only circumstance I can imagine where a kite will fly with its "back to the wind" is when the pilot is moving downwind faster than the wind is blowing. It can happen temporarily in traction kiting. Of course, as you point out, a kite on one line just won't do this.

  There will surely have to be some kind of multi-line control adapted to the kite, for this to happen, and I'm not so sure that the FlowForm, is the kite for this application.  "Collapse",  comes to mine.

Yes.

 

Also, as you have mentioned, kite surfing has already been invented, is quite controllable, and tacking into the wind is done all the time, just as in sailing, but again, that sail is quite maneuverable, via the control lines.  All the mystery and kinks have already been worked out.  Sounds to me like Guy may be trying to "re-invent" the wheel, and adapt it to the SUP. 

True enough, but reinventing the wheel is how we get better wheels, or at lest different ones. At the very least I'm sure he'll have a lot of fun and learn a great deal in the process. The automatic control seems like the most interesting part (to me), but to get to automatic control, first you've got to have control.

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True, true............all true. (And speaking of a better wheel (tire), Goodyear works on that, every weekend !)

As for the downwind / stability issue, I was assuming, that the FlowForm would indeed be symmetrical (it's supposed to be new, or recently purchased), and stable, with the use of a drogue or tail of some sort.

And pilot moving downwind, faster than the wind speed - I have a hard time visualizing that, with a typical SUP, as seen in the videos.

I agree, this should be an interesting project, and will surely be a learning process for Guy. I hope he will share with us, the final results, in particular, the "automatic control". I believe that's the key point, that we are all missing :ani_victory:

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Hey guy,

Don't want to sew tabs on your kite? Then make them out of duct tape. Sounds crazy, but it really does work well. Gorilla brand is the best. I made a 33 sq ft kite that wouldn't fly smoothly, so I experimented with moving the bridle attachment points up the front of the keels by using duct tape. In shear, that stuff will hold like a dog with a bone.

Cheers,

Tom

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Hi Tom,

Many thanks for your suggestion, in fact I did not "tabs" but holes at the front of the keels to try different settings.

Alas this is not the solution for this FlowForm I am trying.

I'll need to make some more investigations and tries, and as soon as I find a good working solution I'll post it here.

Cheers,

Guy

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