Power Kite Forum

GUAL 8 m^2 Foil Taction-Jumping Kite (Homemade)

kandrey89 - 4-9-2009 at 03:28 AM

Hello, I'm a regular forum member of kitebuilder.com and I decided that I should join this place too because of the way my kite interests are going.
First I built a Diamond 6 Foot kite, then I built a 3.1 m^2 NPW9b. Both turned out quite well.

Next on my to do list was a foil, after a lot of help from knowledgeable people I found some designs and guides for a few specific types of kites, it was either going to be SPEED or GUAL.

I decided to build a Gual 8 m version, so that it would be better suited for jumping in 6-12mph winds, although I'm not sure if that's too low or too high, I'm hoping it will do. BTW, I'm 170lbs.

I'm still in the planning stages of the kite building, but I'll just throw out some preparations that I've already done.

1. I've looked through the kite plan, and pretty much understand every aspect of the construction
2. I've pre-calculated the approximate amount of material 0.75oz RS Nylon I would need for the sails, the approx price for 36 yards of 60" wide fabric is $4 per yard = $144
3. I am leaning towards buying a pre-made quad line set from this ebayer, whom I found via this forum - http://myworld.ebay.com/liquidatedsportsltd/ he sells Flexifoil 25m Lines 4 Set - kiteboarding kite kiting
2x150kg/330lb & 2x100kg/220lb BRAND NEW!!!
every\almost every day, and the strength range seems almost close to what I want.
4. The bridle lines that I would like to purchase from goodwinds.com are:
150# - 350 feet -> 400 feet safe margin (100 foot spools) ($0.06 per foot) = $26
200# - 54 feet -> 100 feet safe margin (100 foot spool) ($0.09 per foot) = $9.5
5. The patterns will be printed on 30"x42" sheets, which I will glue together and cutout each pattern, approx 22 sheets total, or thereabout, HUGE :/

Although I haven't had a chance to use double sided tape, I expect to rely on it to sew the parts together and keep them from coming apart, because on such a big project I just can't afford to use scotch tape all over the place.

Well, so far without any actual building, I'm pretty much out of talking. I'll be busy with school, meanwhile I'll try and finalize the materials list which I will need for this kite, so that I could all order it at once and save on shipping.

The plans for this kite are located at http://www.wingine.nl/
My clone thread on kitebuilder forum is http://www.kitebuilder.com/forums/viewtopic.php?t=8142

Feel free to offer suggestions, but don't be disappointed if I'm not inclined to accept them, because I have a very limited experience with kites, 1-2 months with big kites, and a few sessions with a quad-liner NPW9B, although I got the hang of it, I do not know what's what and how. Thus in order to keep the confusion down, and my ability to finish this project without going overboard with suggestions and changes, I welcome you to show the right kind of support :)

NOTE: yes, I know kite jumping is dangerous :wee:

flexiblade - 4-9-2009 at 10:17 AM

That is an awesome site for people inclined to building. Some folks may hint that its easier to buy a couple used kites or cheaper newer kites to help get your wings, which is not a bad idea - good to know what a proper kite can do to compare to your build and then to help fine tune it, but my hat is off to you. After doing a project like the gual you will end up knowing more about foils than most people on this site that have been flying them for years (myself included).

The only suggestion I would make is that the gual appears to me to be a racekite - a higher aspect ratio that gives the kite a more slim look compared to its overall length. These kite are for one thing and one thing only - going fast - they create more apparent wind since they can move through the air faster. This equates to more grunt (strength of pull) but not so much in lift (what's needed for jumping). This kite will be able to pick you up, don't get me wrong, an 8m kite with a 12mph wind and a 170lbs rider is guaranteed to get you off the ground, but a racekite will most likely do it faster and with less dependable outcomes (folding wingtips and canopy collapses are the first thing to come to mind) than a kite designed with lift factors (wider canopy and a pretty harsh angle of attack).

The speed kites look more to the liking for your intended purpose. An arc will give you better hang times and a much safer landing for jumps than a racekite will be able to any day of the week. The only thing that looks a little odd about the speeds are the sizes, a 5.5m arc seems tiny - but I have seen the first PL arc series and a 5.5 was very powerful compared to the contemporary arcs with huge numbers like a 13m, 15m, or 19m even.

Good luck with your project - keep posting up here - I'm sure a lot of people will be very interested to see your progress.

kandrey89 - 4-9-2009 at 07:23 PM

Actually, the Flat Aspect Ratio on this kite is 4.3 and it is lower than Speed's Flat AR, Speed has a 6 Flat AR, however because it is a C style kite it's Projected AR is 2.9 So I guess you are sort of right :smilegrin:

While I was looking through this forum, I went into a thread called Pass the .... kite, and was surprized to see that people were freely passing kites to try from one to another. It'd be a great experience for me to touch one of these kites, check out the construction details, document tips and tricks on how each seam is made and etc. As well as fly one of them, hopefully a 5.x meter or something so that I could ease and prepare myself for an 8 m kite that I'm building. But my low post count and new registration doesn't exactly welcome my getting on the list.

If you don't want to check out the last few pages on my kitebuilder.com thread here is a short summery of what was suggested and why.

I was suggested to use Gual instead of Speed, because Speed has an explosive acceleration\torque? and that for jumping I'd better use a Gual.
I was also suggested to use a smaller Gual because I am not really experienced, so far I decided to stick to building a 8m Gual :o

Gual 8m Projected Area is 7 sq m
Speed 5.5m projected Area is 3.4 sq m

As far as I researched, a minimum of 5 m^2 kite is needed to do jumping, less than that and you encounter problems such as the kite unable to support a safe and soft landing due to the fact that more wind power is needed to power a smaller kite, and that the kite would drop you as a sand bag because it can't support gliding in high winds.

archkiter - 4-9-2009 at 09:26 PM

Cool! Thanks for posting links to where you are getting all of your materials. I have been wanting to try making a 2m Gual. Hopefully I get to it this winter! :)

Keep us updated with your progress- and post some pics:tumble:

flexiblade - 5-9-2009 at 08:29 PM

Where about in Frisco do you live? Odds are you're not too far from Ocean Beach to go check out some flying. The bad thing right now is that there is currently a ban on wind powered vehicles on the beach, buggies, mountain boards and blokarts (small landyachts). But it is still ok to use powerkites down there. With the temperatures at the beach right now being what they are (70's to 80's regularly) they are crowded and the temperatures force the wind off the beach. Things will get better for flying around November (once it cools down) but the winds will be more storm driven (gusty) rather than draws into the delta (clean winds). Perfect time of year for flying is between January and May. If you can make it down to the beach on a day that is relatively cool (62 degrees or less) and somewhat windy (13 -17mph) you may be able to spot some powerkiters that would most likely not have a problem in talking kites.

kandrey89 - 5-9-2009 at 10:12 PM

I live almost 2 miles from Ocean Beach, which is ~30 short city blocks.
You could say I live very close, a 12 minute bus ride to the beach.

I'm privileged to be so close to the beach that I know. I tried talking to a kitesurfer with a 12 m kite, there was a group of them, I got some info out of him, but to me they looked like they would be interested only if I had a kite with me to join them, I don't know, didn't feel like a friendly bunch, only 1 of them out of the group talked to me, the rest kind of bunched up into 3 person groups, :alien:. I pointed them to my NPW9b red\green 3.1 m kite that my Mom was piloting in the distance and got some info like line strength, kite size, material, what he was going to ride while kiting (surf board :spin: ), that's about it. It was 5-7mph and I couldn't believe his 12 m kite wouldn't do the job, maybe there is a big difference between sand and water dragging, and in addition to that maybe there is a lift\drag difference between LEI and a foil kite.

Anyway, I'm trying to come up with some graphic designs for my kite, can't think of anything, if someone knows of a gallery of foil designs, and they could post a link here, that'd be great, might give me some ideas.

I was thinking, black materials have a better spectral absorption than whites, therefor blacks will heat up more than whites. If a black canopy on the top of the foil kite is to be made, would the extra heat inside the foil help it inflate? Now I realize this is only true for inflatable foils and not open vent foils like Gual, but it's just a though that if there is sufficient heat due to the black absorption, then it might cause the air inside the foil to heat up, and because air expands as it heats up, this would mean the pressure inside the foil would increase and hold its shape better. Now this has some question marks to it such as: Is there sufficient heat generation to warrant a temperature increase inside the cells? Will the high speed flying as well as possible air seepage through the material cause the air inside to cool off faster than it could warm up due to the black canopy?

Just some thoughts.

I will post designs, as well as order lists and materials used for this project, and detailed pictures and instructions on how I built it, so chech this thread once in a while :)

flexiblade - 6-9-2009 at 10:57 AM

A black kite will not fly better than a white kite based strictly on its colors light absorption properties - otherwise all kites would be black. I personally like a black kite because its a tough color, makes it look like a weapon.

The kiteboarders were most likely frustrated at the wind quality for the day - an LEI is a heavy kite that can't afford to stall in lighter winds, they will just fall out of the sky. Even a 12m LEI will have difficulty in those winds. If it had been a foil it would have been dragging him all over the place. For this reason flysurfer kites have become very popular - they are not open cell ramair kites (open vents on the leading edge) but closed cell ramair (the vents will close with an internal flap once the kite has adequetly filled with air), this gives them the low wind advantage over LEI and BOW kites (both inflatables).

With the ban on land activities it will be harder to find people with foils and arcs at Ocean Beach (the kitesurfers primarily use LEI's and a few Flysurfers). Since you live close to the beach just keep cruising down to the beach when its windy and I guarantee you will run into someone that will answer all your questions.

furbowski - 6-9-2009 at 11:05 AM

what flexiblade hasn't actually said outright is that the land kiters are usually much friendlier than the Lei boys. landkiters love playing with the wind, basically, and many kitesurfers are much more seeking after adrenalin, the kite is a tool and the love for the wind may not be there.... Lots of crossover, that's a big generalization above but more often true than not in the north american / uk scene. The asian kitesurf crowd is wayyyy friendlier. I know I jump (static) and love the adrenalin rush and have the stupid grin!

so find a guy flying a foil with a stupid grin on his face and you're sorted!

jaymzmn - 6-9-2009 at 04:48 PM

furbowski, i think your comments about LEI and landkiters hit the nail on the head.

Jack1988 - 6-9-2009 at 07:23 PM

all i can say is good luck man, i hope that its a nice kite

WELDNGOD - 7-9-2009 at 06:47 AM

good luck on your build. What kind of sewing machine will you be using ? I have heard that Pfaff makes some of the best, that are capable of sewing slippery ripstop. Keep us posted on your project, and don't forget pics. We love pics:smilegrin:

furbowski - 7-9-2009 at 07:18 AM

Quote:
Originally posted by jaymzmn
furbowski, i think your comments about LEI and landkiters hit the nail on the head.


thanks, but I wish it wasn't so....

@ kandrey, I hope you have a camera, I'm looking forwards to hearing about your build regardless tho!

that is indeed a big kite to bite... But it can be done safely esp. if you get your hands on a good 3m by then.

If you are interested, I can send a 3m legend (kite only) your way. I can't sell it as a kite anymore because the bridle is stretched out, but bridle rebuilds are wayyyy easier than building a kite! It's not top quality, but it's built well enough to be a usable role model.

$30 including shipping from HK and it's a deal.

good luck in the kite draw, btw.