Inflatable UAV

I gave a 6m inflatable to a friend (Chris C) to run UAV experiments with. Here is one of the more spectacular results. It's a shame stuff working is never as photogenic as stuff breaking...

dynamic soaring (fast as shit)
great article on dynamic soaring.

the video: 206mph!

this is way cool. by exploiting the wind speed gradient at the side of a hill, and by oscillating through high and low wind speed areas able to ratchet up the speed of radio controlled gliders to over 200 mph!! holy cow!

interestingly for a high L/D kite this could mean kite-loops in the boundary layer if kept spinning could see the kite accelerate up to it's drag limit. wouldn't want to be on the end of it, but again, interesting to think about. might be a way to go after the speed sailing record if the wind bluff of a 40' wave would produce a sufficient gradient.... but that's just a crazy idea.

some pics.

17m V 2.0

Hello Everyone!

I recently finished making the unbuilt 17m V 2.0. I decided i would try something different with my first kite, which may not have been wise, but worth the try. There have been a few commercial kites with sticks as battens instead of inflatable ribs, due to lack of funds i decided i'd try this. Also the whole kite was made of chikara, very very light worked but it wouldnt have lasted....

First test: 10 - 15 knot wind, had great trouble solo launching the kite as the L.E wasn't stiff enough to make the kite into the half moon shape, also the added weiht of bamboo battens kept the side down. Eventually i got the thing into the air, it pulled pretty hard for that wind(never flown a kite bigger than my 11.8 wipika) and turned extremely fast (faster than my airblast!) but when it turned the tips moved inwards and it ended up jellyfishing, also when powering out of a turn it would jellyfish.

Second test: 15 - 20 mph.Tried to solo launch disater, kite got tangled (no inflatable ribs to keep it rigid) and it got ripped in a few places but fixable. Dont think kitesurfing with this kite would have been be possible.

Still think their maybe sum possibilities for a batten kite, less drag and expense but difficult to pack away and something would have to be made that would attach to the L.E to keep the wing rigid.

Learnt a great deal though, which most people already knew: dont try save money because you end up spending twice as much in the end (now building 15 m!)


Posted by gwaters at January 12, 2005 07:23 PM | Comments (0)

Hanley Innovations Guide to Aero..

plain english online guide to aerodynamics.

I haven't forkedoverthe $10.00 yet, but looks a better investment than $70 for a wind forecasting service..

Chris Gough on wind range

Got this great email from Chris Gough regarding various methods for increasing kite range. I love the way his email ends with "I'm
numerate and can google, so don't shy away from concise technical rebutal"

that's hot. Anyway, look at the extended entry for some Q's and A's.

Continue reading "Chris Gough on wind range"

My excuses...

So there hasn't been a lot of stuff being posted lately.

Here is the main reason:

My PhD thesis! I'm now Dr Saul. It was at Massachusetts Institute of Technology and was on self replicating machines and the math and geometry of making arbitrary 3D shapes from linear strings.

I'll post all the cute videos when i get a chance.

Then I moved to San Francisco! Yay the Left Coast. Much nicer out here than boston, but the winter wind is dissappointingly low. Waiting for those summer thermals. I've a new company with 4 colleagues:
excuse the website, it sucks right now but will be upgraded shortly.


awesome trip

across australia by kite. serious kudos to this guy (and even more to his support team).

Thanks to David Pryor for the heads up.

My Right Knee

I can't really blame this on kitesurfing, but it might have been part of the problem... (really attributable to Squash and Ultimate Frisbee and football).

Anyway, this has been a 6 month dampener on kiting... luckily after this surgery only 6 weeks to back on water time.

Here are the gory details: photos of my stretched ACL and torn medial meniscus cartledge. The cartledge was trimmed. Amazing surgery... a flashlight/camera/vacuum cleaner is stuck in one side of the knee and a pair of hedge trimmers in a hole on the other side. Walked out of the hospital same day and the previous pain was gone immediately!

Thanks to Dr Simon Tan of St Vincents Sport's medicine for the cut & paste.

Violators of Copyleft and Open Source.

So, seems that no-one understands what NON-COMMERCIAL use means.

That means you can't use the designs listed at this site for commercial use.

That means you can only use it for hobby and experimental use.

nobody build kites anymore

well its been quiet around here lately nobody building anymore?? no new ideas/plans i would have thought that you's would be on about a 5th line by now?? or is the good deals on new kites lately better and less hassle than building one?? you may ask why i am not building or posting new ideas then?? well over the last couple of months i just havent had the time because of work and family ties... but i really want to wipe the dust off the machine and build a new kite but i have no spare time to do so.........

anybody then???

duct-tape kiting in africa..

This was sent to me from Johhno Baucke via email. The guy sounds like he has the perfect zeroprestige attitude... here's the story:::

Collapsing image

Flying!! image

Laidout image

Launch image

Ribdetail image

Mini Keg in fridge image

Might be a good read for those who peruse the blog? What happens when you let a kiwi and an aussie loose in Africa with a couple of tarps....

Working on an trackside wheel monitoring project in Richards Bay (South Africa), we found ourselves with an afternoon to spare. We had several unused tarps lying around site, so decided to make a kite to amuse ourselves.

Attempt 1 was pitiful. We had enough old coke bottles etc lying around, and decided we could use these to give us a semi-rigid leading edge and ribs. After cutting out the heavy bits and wrapping a bit of tape around them, it didn't seem too bad. However our extremely dodgy kite shape resulted in something that flew more like a parachute than a kite. I still like my PET bottle idea though.

Attempt 2 was actually pretty good. We had no real way to get a pattern onto the kite without either spending money or some actual effort, so we just printed out the canopy of Saul's 4.5 metre kite (scaled down to 75% to fit our two tarps) on a bit of paper with the key dimensions and just drew it onto the tarp with maker pen.

Ribs - polycarb plasticy stuff cut out into roughly the right aerofoil shape were taped inside the kite.

LE - we used some plastic flexible conduit that we had lying around site, taped on (duct tape is fantastic stuff). This was probably the heaviest part of the kite, and although it probably helped revision 1 fly, it probably held rev 2 back a bit because of the weight.

Anyway, photos of this baby are attached.

It flew, but not well. As soon as you pulled it across to the side, the edge would collapse and the thing would fall to the ground. So we installed a spar across the bottom of the leading edge and it made a world of difference. The spar was made from two lengths of polycarb bent down the middle and taped into a square section for rigity.

Bricklayers line for lines, a length of pvc pipe for a bar, and we were away laughing. No serious wind, but still a bit of fun. Total cost - R12 which is just over 2 australian dollars for some extra line.

It would still collapse sometimes towards the edge of the wind window - I reckon 2 or 3 more spars would have prevented this (wagon wheel-like configuration), but it wouldn't have flown in the amount of wind that we had with much more weight.

Also attached is the trips second greatest engineering feat - mounting a mini-keg in the hotel bar-fridge. Once again - duct tape - fantastic stuff.


Safety UN release... MORE GORY DETAILS

Well, as if I needed more stitches to remind me of the need for safety and checking your safety equipment....

Only this time it was the failure of my Naish 2003 quick release. Let the bar go, but the tether line jammed and the kite remained powered up.... Whilst trying to remove the safety leash the safety clip, a plastic number broke and sliced through my hand....

Check your safety over and over and over again... Cost me 5 stitches and two weeks off the water....

Fortunately the doctor at Palm Drive Hospital (Sebastopol) was lovely and told tasteless jokes with me as he stitched the hand together. Altogether a fun afternoon, but the 7 hours in the emergency room would have been better spent on the water.

Posted by saul at June 4, 2004 07:12 PM | Comments (1)

Luke Roberts 8.5

yet another....

"just sending you a few photos of my kite, that i completed early this year. Although there were times during building that i felt like giving up, It was a great feeling completing it and flying it. I look forward to taking it surfing (when iv re-enforced the rib-LE joints).

Thanks for everyones info and advice.



Posted by saul at June 3, 2004 07:19 PM | Comments (0)

Ian DeWitt's 8.5 V2

awesome, another built, flying 8.5.

Posted by saul at June 3, 2004 07:17 PM | Comments (0)

Mark Frasier homebuilt boards

Hi Saul,

You don't know me, but I know some of the Nahant crew (Paul Lawrence, John
Ruggiero and Dan D. come up here to Maine to buggy at Pine Point once in a
while). I love the Zero Prestige site & concept. Thanks for keeping it

Anyhow, I have been playing with plywood boards lately. I've made:

A flat 3/8" fir plywood 120x45 w/cloth bottom & polyester resin. The
catalyst was old and it never really set up right, so I don't use this one.

A flat 120x40 1/2" home depot birch board with glass/epoxy bottom and 1.5"
Tracker plastic fins (smileyface board in attached pics),

A lightly rockered, hollow Stunt Kites 3-style board (4 layers of 1/8"
baltic birch with the middle two layers partially cut out, glass bottom,
epoxy coated, 2" fins, painted w/Epifanes yacht enamel). This one rode
great, but I used cheap glue for the lamination and it keeps cracking open.
Currently awaiting repair.

Lightly rockered 150x40 baltic birch board from 2 layers of 1/4" glued with
waterproof wood glue, coated in epoxy & painted with Epifanes and
Painty-brand paint markers. 2" fins. This one is barely lighter than water,
but rides great. (board001 pics attached)

A flat 3/8" baltic birch 150x38 squarish finless board, coated with epoxy,
painted with rustoleum and Painty markers. No cloth or fiberglass. Haven't
tested this one yet.

And I have a couple more in the works.

For fins, I have used Tracker fins from Omnitech Engineering (tough plastic,
under $5 each, available on the web). I know you guys aren't all that hot on
fins, but I find that they help in the chop and keep you from losing as much
ground when landing jumps. I also picked up a couple of packs of Wipika fins
from Real Kiteboarding's odds & end basket for 2 & 3 bucks for 4!

For straps, I use a piece of webbing on top, roll-up plastic sled material
under that, and a 3 layer piece of neoprene from some sort of workout belt
thingy. It's all stitched together with a Speedy Stitcher sewing awl. The
sleds go for about $2.00 and one will get you maybe 6 or 8 sets of straps.
The neoprene belt is about $5 at Walmart and is enough for 2 pairs.

For deck pads, I use the black floor pads that they sell in the exercise
isle at Target and/or Walmart... it has puzzle-piece edges that allow you to
lock the pads together into a 4'x4' or 8'x2' area. It is good, tough, firm
stuff, with a little texture on the top and a smooth bottom. Non-obnoxious
color. Maybe a little thick for my liking (1/2"). I believe it is used under
wieght machines & the like. A pack of 4 2'x2' pieces is roughly $20.

I get 5x5 sheets of Baltic Birch at Maine Coast Lumber's Westbrook branch
and have them cut it into 3 pieces for easy transport.

I have been using Mas epoxy, but want to get some cheaper stuff from US
Composites next time.

I have yet to break a solid board, but I haven't tested out the 3/8" birch
yet. Do you guys end up breaking many boards? Do you find that the cloth on
the bottom adds a lot of "snap-proofing", or do you do it mostly for wear
resistance and looks?

Feel free to toss any of this on the blog if you think it'd be useful or
interesting to anyone.

Thanks again for all the good info.

Mark Frasier
Portland, Maine

a few answers (from me, Saul):

fabric on bottom mainly to make them last longer and look better.... ding
resistance, it does add considerable weight over a plain birch ply.

broken a couple of ply boards but only after they become waterlogged and
weak with tonnes of use.

Posted by saul at June 3, 2004 06:57 PM | Comments (0)

Sailmaker's Apprentice & leach lines.

This book is an amazing reference, around $25 at amazon.

And this is the best way to do the leach line to prevent having a tight leach. Use a very light line that stretches quite a lot (more than spectra flying line) dyneema seems to be ok, 120-200lb breaking strain.

Posted by saul at May 31, 2004 05:52 PM | Comments (0)

Funny Fittings


This is a "funny L."
I use funny L's when connecting sprinkler heads to poly pipe. Using poly pipe makes the head's position more flexible.
Finally, after much experimentation, I found that I could use 1/2" funny pipe and the barbs of the funny L to create a leak-proof valve.
I put a 6" section of funny pipe in the bladder and then insert the 1/2" funny L (barbs) into the 1/2" funny pipe, from the outside of the bladder. Make sure you poke a hole in the bladder material after you have inserted the funny L and make sure that you get the funny pipe over the last barb of the L. Cut the excess 6" funny pipe down to about 1" and buffer the hard edges with duct tape. Then you can seal the open end of your bladder and test.
I've tested 4 bladders with this and I have no leaks. I use 6 mil VIsqueen and have not tested it on anything else. 6 mil (black) is some tough stuff. A funny L can be bought at the hardware store for about .25 and the funny pipe is about .25 a foot.
I then cap with a 1/2" threaded cap. I always use Teflon tape on the threads. A better method of filling would be to invent a one-way valve in that funny L.


Posted by jthomas at May 27, 2004 04:58 PM | Comments (0)

Painted Kite


I'm almost done. There are a couple leaks and I need to cap the ribs and LE with something.

Posted by jthomas at May 24, 2004 01:55 AM | Comments (2)


Paul Walsh did hid final year project on CFD of inflato foils. Here are some interesting results in a word documents.

Download CFD in word.doc

Posted by saul at May 23, 2004 06:17 PM | Comments (0)

Metal Halide


My new light. Free!!

Posted by jthomas at May 20, 2004 01:59 AM | Comments (0)

My Kite is My Canvas


Posted by jthomas at May 20, 2004 01:29 AM | Comments (0)

Hood River

Big wind and as I was packing my equipment, the king of the dirt mound (beach) told me that I would be risking my life to take out the Tyvek special. My lines, kite, bar, harness, leash and board are all home built. These guys have store bought gear and there was only one cool individual who asked me about my stitching or construction technique. I got scared and went to a place down river. The wind was messed up and I couldn't generate enough power to get up on the board.
Next weekend I will work the wind with my kite and damn negative assholes.
My gear is solid, not pretty but safe.

Posted by jthomas at May 19, 2004 01:55 AM | Comments (2)

Yet more materials tests

The other day I found a piece of home depot tyvek blowing around in the wind so I thought lets do some more tests. I read that the fabric industry uses a 2" wide strip of fabric for their tests so all these are done with a 2" wide strip, carefully marked and cut out of a 6" long seam on the materials. The seam is a 4mm plain stich along the seam line, the ends folded down and a 5mm wide triple zig zag sewn to hold them down. The tests were perfoemed on the lat pulldown bare of a universal gym. All strips of material were treast exactly the same. the results are:

ripstop nylon - lift 40 lb, fail attempting 50
heavy tarp - lift 60 lb, fail attempting 70
light tarp - lift 30 lb, fail attempting 40
tyvek - lift 20 lb, fail attempting 30

Then I resewed the tarp seams by doubling the seam allowance and floding the ends under when sewing the zig zag part of the seam.

light tarp - lift 60 lb, fail attempting 70
heavy tarp - lift 110 lb, fail attempting 120
BIG IMPROVEMENT!!!! in addition the seams didn't distort or pre rip much. This puts tarp into the realm of dacron and makes it a useful alternative.

I read yesterday at lunchtime that there all all sorts of Tyvek varying from 7.5 lb to 75 lb/ in tensile strength. THe stuff I think you want for kites would be the #1460UV which is the 1.74 oz UV resistant boat cover truck tarp type of tyvek.
Have fun,

Posted by swerhone at May 1, 2004 12:25 PM | Comments (0)

HTML is Fubar

I didn't see the 1" strip specification in your test. However wide this material is?

I tied a motorcyle tire and a chainsaw to it. The fish scale read 45lb's. I pushed down on it and got to 50lb (the scale limit). I got my camera out. I pushed down again and it broke at the seam and the granny knot tied to the tire and chainsaw. Single flat fell seam, 7 stitches per inch, home depot Tyvek.

sorry about the HTML goof

Posted by jthomas at April 11, 2004 12:49 AM | Comments (0)

Alternative materials test

I had some spare time so I ran a few tests on some alternative materials. I cut some 1 inch wide strips of tarp and dacron, sewed them together with the standard kite seams (4mm straight and 5mm wide X 1mm triple zig zag) and tested their strength on a universal gym pull down bar. For people thinking of building a kite out of tarp the results are as follows:

Approximately 5 oz dacron to 5 oz dacron (from an old old windsurfer sail) - lift 70 lb breaks attempting 80 lb. The stitching broke not the material.

Approximately 1.5 oz ripstop nylon to 1.5 oz ripstop nylon - lift 40 lb break attempting 50 lb. The material ripped about an inch away from the seam leaving the stitching intact.

5.4 oz 14 X 14 heavy duty poly tarp to 5.4 oz heavy duty tarp - lift 40 lb break attempting 50 lb. The material ripped out of the seam.

2.9 oz 10 X 10 light duty poly tarp to 2.9 oz light duty tarp - lift 20 lb break attempting 30. The material ripped out of the seam.

2.9 oz light duty tarp to 5.4 oz heavy duty tarp canopy to leading edge type seam - broke attempting 30 lb. light duty tarp material ripped out of the seam.

The tarp material was noticably stretchier than the nylon or dacron. It would be nice to run the tests on something that could measure the elongation.

I then sewed some more seams and doubled them over (rolled them) but there was no difference in seam strength. Dacron and nylon are clearly way, way stronger than poly tarp. The light duty tarp was the standard Wal Mart cheap blue tarp (It was actually Canadian Tire cheap green tarp) and the heavy duty tarp was the standard higher price stronger tarp that can take more abuse.
I am not sure what seam strength is required but it is worth considering some testing before doing all that work. The elongation distubs me a little. I wonder if anyone has tested Tyvek? The price difference between dacron and alternative materials is so great that the lower strength may be a worthwhile trade off if you aren't going to stress the kite much. If you can get second grade material the cost difference is only about $150 if you are real careful laying out the pieces and don't mind odd colors.
Tyvek seems to be a generic term for house wrap, at least here in Canada. It varies from actual Tyvek brand house wrap that kind of looks like Tyvek should, but only comes in 10 ft X 100 Ft rolls (110 sq yds) from home depot to stuff that looks like cheap blue tarp only white color from the Co-op home center. The Tyvek house wrap looks different than the envelopes and the disposable painting suits so it might be a real job to find suitable durable material.

I looked up pressure cylinder forces in an old textbook and the stress on the leading edge and rib seams would be 1/2 the pressure in psi times the diameter in inches of the tube with the results in pounds per inch of seam; so for a 4 inch diameter tube with 4 psi pressure it would be 8 lb per inch of seam.
The only canopy seam that would be a problem is likely the shortest one joining the tip panel to panel 2. it is about 36 inches long so shouldn't recieve more than 10 lb per inch unless something real bad is happening.

Posted by swerhone at April 8, 2004 11:29 PM | Comments (2)

Tyvek Again

Bladder in the LE and packing peanuts in the ribs

Posted by jthomas at March 31, 2004 08:47 PM | Comments (0)


My apologies to everyone. It appears zeroprestige is under a blog spam attack. There are not many good options to prevent it, apart from shutting down comments which i don't want to do. Basically just ignore the online casino / pharmacy / drug / porn advertisements. It's part of the hazard I guess of a site getting a lot of hits.

If you are someone who spams, buggar off.

I think it is perfectly reasonable to cut the flying lines and shoot the LE bladders of anyone involved in the spam industry.

any bets on how long before this post gets spammed?

To latex or not to latex

I must admit that my enthusiasm for latex has faded away a bit.

Continue reading "To latex or not to latex"

Bull Kite Factory

I visited Bull Kite's factory in Tarifa last week and spoke to one of the guys there. He let me take a couple of pictures which might be of interest to kite makers.

It's certainly worth a visit if you are in the area!

They operate out of a warehouse near the centre of town and the place left me drooling - it's an Alladin's cave of kite bits + pieces!

They also make windsurf sails, board bags and clothing and you can see a guy sewing a sail on the big blue sewing table in the picture. The white table on the left with the red roll of cloth on it is a CAD plotter/cutter.

All the kites are designed using CAD software, they don't use any kite specific design package and the guy I spoke to hadn't heard of Surfplan (he has now :-))

They sew all kites and sails in Tarifa and because of this I think they struggle to make much money.

They make their own bladders on location and offer a custom bladder service - details are on their website They have the same problems sourcing TPU as we do...

There were a couple of kites on display and they looked good - much like other commercial kites I've seen.

I'm not plugging or recommending Bull Kites - I have no idea how they compare with other kites, just thought someone might find it interesting!!

Sky Sails.

Wish there were photos of real protos here, but all the same cool looking stuff.

Seamless Kites the Way to Go??

Wow, Mal posted some information about 3DL sails on the inflatodesign group.

Here's a link describing the process:


I especially like the hang-glider harness used to reach over the top of the sail!

Garth's 11.2m

Amazingly small world department. I went to high school with Garth, we both went in different directions around the globe and i heard nothing until he asked if I was the same Saul he went to school with when he got interested in building kites. Well, YES. Anyway, here is his first kite, 11.2m ZP. Nice looking work.

Monkey Kites

I may as well dispell the myths and rumours upfront.
Yes it is true, my designs are now being used by my sister for
My sister has been a designer for the surfing industry for 12-15 years and has sourced materials and done manufacturing and retail around the world. She saw an opportunity for fairly priced, high quality kites realising that not everyone would want to make them themselves. As a brother I naturally wanted to help her in this endeavour which she has based in Sydney, Australia.

The designs are not exactly the same as those on this site as they have been tuned to be extremely reliable and predictable and have all the good things that people would want in "production" kites. You should still feel free to make any of the designs posted at this site and you will not be disappointed for your efforts, i still prefer to fly something i've sewn myself, it's a double blast, plus it lets you think about all the things you'd change on the next one you make while you are out there and the wind drops.

One of my conditions for supplying her with designs is that I would continue the zeroprestige effort. It is too rewarding to see all the excited kite builders out there trying their own things and pushing the aerodynamics in new directions. As i see it everyone wins, fairly priced kites will be available to those who wish to buy them, and zeroprestige continues to push the edges of theory and design and here I can try all the stuff the doesn't work, or works only for very specific conditions. This year I expect to build some very weird and hopefully very interesting kites with new behaviour.

My big thanks to all the inflatodesign (yahoogroups) and zeroprestige and foildesign (yahoogroups) contributors who passionately push the boundaries and openly discuss new designs, methods and ideas. All those people are the Dogtown Z-Boys of kiting, developing new stuff for the personal gratification, and ignoring the high-label consciousness of a lot of other consumers.

My biggest interest is in making the thousand year old tradition of designing, building, and flying kites available to more people. I love the fact that it is a sport that puts you in touch with the elements and doesn't require fossil fuels.

I'm sure there will be a lot of shit fly around from retailers and others in the industry and lots of crap will be said. Oh well. They can go and fly a kite. Hopefully a monkey kite?

What and why is is a weblog devoted to the design iteration of kitesurfing and kitepowered sports. Principally we are interested in furthering the sport by enabling an 'open source' (shared knowledge and documentation) approach to kite-building and to the building of bars, boards, ice and snow equipment, and things kite-powered in general.

You are encouraged to add comments and knowledge to any of the postings. If you would like to be able to add content directly such as kite photos and surfplan files, email me and I will give you an account on this blog.

The files on this site are only available for hobby/homebuilt use. Any commercial use is not allowed.

VIDEOS worth Seeing
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Inflatodesign Yahoogroup
Foildesign Yahoogroup
Surfplan by David Aberdeen
Saul's website at MIT Media Lab
Eric's website at MIT Media Lab
Tim's website at MIT Media Lab
These are kites that have actually been built, flown, photographed, and tested. Flight reports of varying quality exist for each of them... Rating System:
***** : lovely. 2004 commercial quality performance.
**** : really good. Compares favourably with '02 / '03 kites.
*** : flies, you can have fun, safely, nothing special.
** : flies, badly. you can learn.
* : don't let your friends fly this kite..

Rob's 23.6m
Rating: ***-****

Rating: *****

Rating: *****

Rating: *****

Rating: ***

Rating: *

Rating: unrated..

batwing 8.5
Rating: **** (from what i read from John-e-boy!)

Tim Carlson 3.5 trainer
Rating: unrated..definitely flies..

Eric's 5 trainer
Rating: unrated.. definitely flies..

12.5m from Jerome, Brazil
Rating: ***-**** (from what i hear)
5m 2 ribs
Rating: **

12.5m from George Warner
Rating: ***-**** (but i've only seen it, not ridden it)

Rating: ***

12.5m Inflato-Tips
Rating: ****

8.5m Version II
Rating: ****-*****

8.5m Original
Rating: ***-****

7.5m IAP kite
Rating: **-***
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