DIY Foil Kites

[cleepa]

Congratulations! Would love to see pics of them up in the air!

[ozchrisb]

Foilholio: I'm using http://sourceforge.net/projects/foilmaker/ foilmaker as I used it a long long time ago and know it makes nice patterns. Unfortunately the bridle design on it is very old so I'm trying to update that. I've also don't some custom bits for cell stiffeners etc.
stefmoris: I agree that we need a laser cutter! I build 3d printers in what other spare time I can find and a laser cutter would be very simple. The only issue I've found is getting extrusion long enough to cut at the full width of most fabrics. There are some very cheap lasers around these days that would be perfect for this. I'd want a pen too, so that you could mark bridle points, registration marks etc. I'll update this thread with some photo's once I've made progress.

[foilholio]

Did you update the software? I would love to understand some more about bridle design. Where should I start reading?

Extrusion by it's nature is capable of essentially unlimited lengths. I know with the large metal suppliers/manufacturers they will supply as long as the truck taking it. Maybe you just need to move up the supply chain and get something freighted.

I have noticed some dot marks on the seams of some flysurfers. I thought it looked a good way to keep things aligned. I read an article by peterlynn talking about seam miss alignment. Basically down to the sewing machine slowly bunching one bit of fabric more than the other. I remember numbers like 20mm for 1 meter of seam. Would obviously be more of a problem with lower AR higher cell count kites I would think? Did any of you find many cells well out of alignment when you got to the TE? How did you fix it?

I also vaguely remember A1,A2,B1,B2,etc cut into the straps.

Lastly I stumbled onto a kite maker forum on yahoo which was private. It had quite a few members. Are any of you members? Is it a treasure trove for this stuff?

[kitexpert]

I have used Surfplan since it's been available, before that Foilmaker. Sp is sophisticated 3D design program, Fm quite old and primitive one, it lacks many many things Sp has.

"I have noticed some dot marks on the seams of some flysurfers. I thought it looked a good way to keep things aligned."

These are alignment points. Surplan has that option and it is worth using.

"Basically down to the sewing machine slowly bunching one bit of fabric more than the other. I remember numbers like 20mm for 1 meter of seam."

This depends sewing technique, fabric bias and quality and used machine too.

"Would obviously be more of a problem with lower AR higher cell count kites I would think?"

There is one easiest (possible) sewing order because of practical reasons. So, left and right side of the cell easily have opposite alignment errors if kitemaker is not careful. High AR kites are the most sensitive to everything, thick and bulging low AR low cell count kites are more tolerable to errors.

With alignment points this problem is avoidable, without them not very skilled sewer can not do exact work (if not using glue or tape). Used fabrics are not very easy to sew, they are thin and slippery.

"Are any of you members? Is it a treasure trove for this stuff??"

Not me. "Treasure trove for this stuff" may be closer than you think...

[foilholio]

Think this is the group I was referring to https://groups.yahoo.com/neo/groups/Foildesign/info

I remember reading that some well known names posted there. They dont seem very active now.

[ozchrisb]

Think this is the group I was referring to https://groups.yahoo.com/neo/groups/Foildesign/info

I remember reading that some well known names posted there. They dont seem very active now.

I am/was? a member of that group. It kind of died out years ago when LEI's took over. We were mainly making buggy kites anyway.
Surfplan is certainly more up to date than Foilmaker. But, you need to buy it to do useful things, like export the patterns for printing.
I've got Foilmaker to build on my computer and I've tried changing a few things, I added another line to the DXF so that I could make the rib reinforcement. The bridle part is a lot more complicated. There is an built installer on Sourceforge so you should be able to install it if you want to try it.
Re: alignment marks. The technical term for getting the ribs to line up is call registration. If you're sure the plans are correct and the rib doesn't line up and the end you unpick it and sew it again. Usually the ribs end up too long because you tend to pull on them and stretch them a little, plus the sewing machine feed dogs don't grip exactly the same as Peter said. The pen on the laser cutter would also be used to mark things like the bridle points, cell number, reinforcement points etc
Most sellers keep the extrusion length around 1.5m for shipping reasons, but also because it's not really guaranteed to be straight over a much bigger length than that. Anyway I need to CAD it up to see what the lengths would really be like.

[ozchrisb]

For bridle design:
[vimeo]http://vimeo.com/9488886[/vimeo]
This one is a really good explanation of the mixer system for the guy who popularized it on kites.

[kitexpert]

"But, you need to buy it to do useful things, like export the patterns for printing." -ozchrisb

I have "exported" patterns to normal laser-printer, not buying the program. It takes few hours to print and tape patterns for a big kite, so not much. If you can use A3 or bigger paper, much less.

Surfplan: TERMS OF USE:

"5) PERSONAL USERS: This program is freely useable for personal non-profit use. Have fun!"

Printing is much more economical and easier than in Foilmaker and has many useful options. This alone makes Fm obsolete.

Cutting all the parts with scissors and marking needed things by pencil is a small fraction of the work in kitemaking. Precise sewing takes time, ditching unsuccesful kites and doing it all over again takes even more. And when you do that several times, it takes years.

Armins video explain the basics, mostly speedsystem. But it does not explain why camber increases when sheeted in. FS's bridles have been quite conservative and unfortunately not very good at keeping their adjustments.

For bridle design Surfplan is very good, almost everything is possible with bridles. But you must master it and know what you want.

Some modern gliders have interesting bridles to study and to apply for kites.

[foilholio]

What is a glider make model I could look at with these bridles?

[ozchrisb]

"But, you need to buy it to do useful things, like export the patterns for printing." -ozchrisb

I have "exported" patterns to normal laser-printer, not buying the program. It takes few hours to print and tape patterns for a big kite, so not much. If you can use A3 or bigger paper, much less.

Surfplan: TERMS OF USE:

"5) PERSONAL USERS: This program is freely useable for personal non-profit use. Have fun!"

Printing is much more economical and easier than in Foilmaker and has many useful options. This alone makes Fm obsolete.

Foilmaker lets me export to DXF and the arrange the patterns for printing on a plotter. To export to DXF in SurfPlan you need to pay. But yes SurfPlan is better if you want to get up and running fast. I've seen the paid version and it does a whole lot more too!
I started playing with Foilmaker again because Peter released the code and I'm interested in open source kite design software. It's a quick start, although the code is C++ and not exactly modern windows. The skin shaping on it is excellent, I know for sure it produced some commercially made kites.