DIY - Strutless bow kite

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Re: DIY - Strutless bow kite

Postby reyrivera » Fri Mar 21, 2014 8:09 pm

I only have a portable double step sail maker machine, got it from sailrite. I sold my triple step a long time ago because it requires a lot of space. If I'm repairing a client's kite and needs extra reinforcement, I just do an additional pass through and carefully turn it into a cross stitch, takes a little bit of extra time, but way better than the the triple stitch zigzag, 'cuz now you have quad stitch cross zigzag sewn with extra tlc.

It's also convenient for me to toss the machine on the back of my truck and do johnny on the spot modifications on my test kites.

ozchrisb wrote:Do you have a triple step sewing machine? The machine in the photo looks similar to the sailmakers one I have, but mine only zig-zags no triple. Not that I'm sure you actually need it, just curious about where you might get one from.
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Re: DIY - Strutless bow kite

Postby reyrivera » Sat Mar 22, 2014 12:13 pm

Let's talk about bladders.

I have my tentative final design, pending the final decision of leading edge diameter size. I want to have a custom size, but can't find sources where I can buy Thermoplastic polyurethane sheets.

I can easily get polyethylene sheets at home depot or lowe's, but not polyurethane. This polymer seems a bit too rigid for kite applications, and a higher chance of exploding on a kite crashed hard on the water surface. Anybody have ideas where to get polyurethane sheets. For quick tests this will do. I guess since this is an experimental kite, I will find out how long polyethylene based bladders will last.

I guess the simplest way is to make the leading edge diameter identical to manufactured kites so I can order the same material from airtime.

Can anyone provide diameter size of their 11 or 12 meter bow kites? Which 11 or 12 meter kites you think has large diameter leading edge?

As a side note, since polyethylene can be recycled, if the material is good enough for kite applications, its worth testing it. I don't think TPU plastic can be recycled, so they typically go straight to landfill.

Thanks,
Rey
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Re: DIY - Strutless bow kite

Postby kitenaked » Sat Mar 22, 2014 9:33 pm

My Wainman's bust voluptuous LE bladders
Chris

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Benicia Kite and Paddle Sports
238 1st Street
Benicia, CA 94510

510-900-WIND (9463)

http://www.kitenaked.com
Wainman - Cabrinha - Shinn - Underwave - Hyperflex
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Re: DIY - Strutless bow kite

Postby sflinux » Sun Mar 23, 2014 7:24 am

big leading edge bladders:
Wainman Boss Rabbit v1.0; Center = 19 cm, Wingtip = 7.6 cm
Windwing Rapture1-12M (not 2); same measurements as Boss

I pumped up the kites and tried to measure the projected width of the leading edge at center/wingtip.
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Re: DIY - Strutless bow kite

Postby reyrivera » Mon Mar 24, 2014 5:19 pm

Thanks a lot for the specs sflinux and kitenaked.

Based on the behavior of my small kite design, I made simple tweaks to fix the following issues:

1) The kite do not overfly outside the wind window

2) Kept the simple bridle settings. Went to the reservoir today and tested the kite with no pulleys, small kite was surprisingly stable, but more pull and slightly heavier bar handle. I can go either pulley or no pulley on this design.

3) Slightly thicker leading edge to compensate for struttless (or strutless?) design. Per kitenaked's description of his Wainman's, my kite is now as voluptuous as Anna Nicole, but more nimble than Xena. Leading edge center diameter is at 20 cm, wingtip at 8 cm. Chris, I will call you sometime within the next few weeks as I need to order a bladder and also a new dynabar.

Will build the kite as soon as the materials arrive. Here is my final design.

Additional notes:
I may have found a good retail/wholesale source of ripstop nylon/polyester source. So I cancelled my current order and got some samples from a different store. Now, if I can just figure out where to find ripstop dacron ...., currently DuPont only makes woven dacron available to sail shops, probably because ripstop polyester dacron is very expensive....
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Re: DIY - Strutless bow kite

Postby reyrivera » Fri Jun 06, 2014 9:11 am

Preview. Will post more after a few wind sessions.

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Re: DIY - Strutless bow kite

Postby reyrivera » Fri Jun 06, 2014 9:18 am

Straightforward no frills/bells/whistle design. Will add the cream once I get a kite that I really like.

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Re: DIY - Strutless bow kite

Postby ozchrisb » Fri Jun 06, 2014 9:33 am

Awesome work. I love seeing that there are home builders still around, part of what got me into power kites originally was that I could build my own. Time to bust out the sewing machine again!
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Re: DIY - Strutless bow kite

Postby sflinux » Fri Jun 06, 2014 11:55 am

Love it. Would be sweet to see some video of it in flight.
That sailrite sewing machine looks pimp.
Watching the Cloud-Heads on the coast has me very interested in the strutless kite movement.
Great work.
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Re: DIY - Strutless bow kite

Postby reyrivera » Fri Jun 06, 2014 12:04 pm

Thanks, will try and borrow video to shoot some footage once the kite is working properly.

For the curious and want to DIY KiteBuild, here's a breakdown on time spent to design a kite from day zero:

    1) 4 weeks to fill my Bill of Materials (B.O.M), I was trying really hard to buy U.S. made stuff, but gave up since everything is made in China. This should shorten to a few days once I have a full source. Cost to build this strutless kite is $350.00, retail. If you are a reseller, it gets cheaper. The most expensive is the bladder, $95.00 ordered from AirTime. I'm still in the process of building my home made polyethylene bladder, not sure how long polyethylene will last.

    2) 2 weeks (80 hours) CAD design, and software simulation. This should disappear once I have a full version where I can base all my other designs.

    3) 1 week (40 hours) sewing.

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