home
hangtime kite design
8.5 m2 kite
15 m2 kite
P-ARC
BOW
bladders
homemade bar
kite skates
surfing
recumbent
othello
mandelbrot set
web design portfolio

ZP 8.5 V2

The ZP85 was the first inflatable kite I made. It was very successful and flies beautifully. It is good for surfing, and feels very powerful, and I have used it when others were using 15 sqm kites. It is very fast turning. Feels very twitchy compared to the ZP15.

It was designed by Saul Griffith on Surfplan.

Download the .sle (Surfplan) file.

Click on the images below for a bigger picture...

The pictures were taken in a very light wind, with Luke Roberts holding the kite near the ground at the edge of the wind window, and I think this accounts for the wrinkles. When the wind picks up it is nice and smooth... I haven't flown a commercial LEI so I can't compare performance.

construction

The kite is made of sailcloth I bought from Bainbridge. I used 7m of 3.9oz dacron for the leading edge and struts, and 7m of AIRX 600N for the canopy. I bought roll-ends and the total cost was about £60. My friend Andy printed the plans out on his big shiny printer at work so there was no fiddling about with sticking bits of paper together! I traced all the lines (seam lines and cutting lines) onto the cloth and cut the pieces out using scissors for the dacron and a soldering iron for the AIRX. My sewing machine is an ordinary cheap domestic thing and I had no problems, although sewing the dacron accurately takes a little practice. There is an excellent guide to sewing on Saul's site. I split the canopy and made the front part out of dacron so as to make the kite tougher. I'm glad I did this because the leading edge and the front part of the canopy tend to get dragged in the mud. The dacron is very tough and can withstand lots of abuse!

flying

Surfing - flies great, relaunches off water effortlessly. Doesn't tend to stall. Turns fast, almost too fast. Doesn't depower as much as the ZP15 - sometimes I would like more depower.

The kite flew first time with no problems except that I was inexperienced! I flew it on handles first but soon made a bar which is much better.

Power is huge and jumps are inevitable if there is a breeze. Turns are smooth although the tips flap a bit in tight turns. Tip battens might help here.

Occasionally the kite will luff and fall out of the sky but mostly it is well behaved.

Launching is usually solo and I have added a fifth line which goes from one of the front line leaders to a bridle attached to the ends of the centre struts. With the LE down and the kite more or less directly downwind a pull on the fifth line reverses the kite into the air, and pulling right or left on the bar will rotate it to bring the leading edge up. Be ready for a big pull when you do this!! I usually have to run towards the kite when I launch like this... I always launch unhooked just in case.

Update on launching!! Jan 7th '04 - The other day it was blowing hard and I took the kite to the local common at lunchtime. There was too much wind but I launched anyway ;-)

I let go of the bar before I was catapulted down the field by the Immense Power I had unleashed, and a split second later I realised that in my haste I had not attached the leash to my wrist!!! Now I know how fast I can run!! Luckily I caught the kite before it was blown onto the road...

Reverse launching like this puts the kite right in the power zone and is best done in light winds. After getting control of the kite again I played around with it, just pulling on the fifth line enough to have it skimming the ground and I found I could get it to move towards the edge of the wind window by pointing the bar at it, in the same way that you would do a relaunch off water. I was too scared to try another launch but I will experiment with this technique...

Second Update Jan 9th '04 - I played around with reverse launching again and I successfully launched the kite at the edge of the wind window using the fifth line to get it just skimming off the ground. The wind was strong again. I don't have a wind-meter but the flags were sticking straight out and when I got the kite overhead I was mostly just dangling in the harness... I did a couple of jumps.

conclusions

This is a great kite, but I would change a few things next time:

• Tips: In tight turns the tips can fold. I think batten tips would be better, and they are easier to sew! Alternatively I would go for rounded tips like I will be using in the next kite. I will also make the whole tip panel out of dacron next time for strength.
• Thread: I used ordinary polyester thread because the only sailmaking thread I could find was a 1lb roll which is enough to sew about 100 kites and has a price tag to match!! The thread I used seems fine in most places but has failed along the LE seam when I pump up the LE really hard. Next time I will find some better thread.
• Cutting the cloth: My soldering iron will cut dacron, but REALLY slowly. So I used scissors to cut it instead. Next time I will use a 75W soldering gun. I have ordered one of these... This should stop the edges fraying because the heat melts rather than cuts the cloth. The fraying is slight and does not seem to be a big problem but it is unsightly.
• Leach / Trailing Edge: There are several ways to finish the trailing edge, I sewed a thin nylon line into mine for strength. Unfortunately the line doesn't stretch as much as the canopy cloth and so the profile is distorted at the trailing edge as you can see in the pictures. Next time I will not stitch through the nylon line, just sew it into a pocket at the trailing edge so I can adjust the tension here like you would on a yacht's mainsail.

Other things to try - I want to have a go at making a recon/jumpstart type relaunch system for the kite, and a pulley bar...

Contact me! redhot@freeuk.com