a simple parafoil to test welding welding methods.

Plastic test foil 1

I had encouraging results in my attempts to weld plastic sheet onto foam but wanted to try something similar to paraplane canopy but smaller.
I decide to make a "kite" of six cells with a similar rib size and profile to what I may use on a large chute.

I downloaded and used foilmaker to generate the profile. I've never used it before and it seemed to have it's own ideas and fight me.

I chose a predefined kite called dominator as the starting point because it had a thin foil with a flat bottom similar to the skysurfer profile.

The pattern was printed on two A4 sheets, stuck together then cut out.

I cut ribs out of foam (camping mat). Unfortunately the foam never totally lost it's curl from being rolled up. I used some strong magnets to hold the pattern down while I marked it. A steel ruler underneath gave the magnets something attractive to head for. The ribs were cut out with good quality scissors.
The inner ribs had lightening holes added using a stanley knife- maybe not the ideal size and shape but close enough.

A clear skin was used mainly to show the innards in these photos. The edge of the sheet was cut straight with the knife and lines marked across the sheet every 10 cm. The cells are wider than I'm likely to use on something more serious.
In this (above) photo the first rib is clamped between pieces of wood to hold it flat and the sheet has been tacked to hold it in place. My modified soldering iron and various other tools are visible.

All the ribs were attached without any problems.
The "B" lines or back lines in this case were added while I had easy access to the "inside" of the foil to be.

The top skin was considerable more difficult to attach. The ribs were unsupported and wanted to flop over or bend.

I tried welding the skin on, both with and without the spreader in place. It was easier with no spreader and the joins improved with practice.
The spreader was made from plastic antenna tubes, syringe tips and a few little pieces of carbon fibre rod to join them together.

The results were fair but there is room for improvement.

Some extra jigs would help but I probably have to decide on the exact profile shape and size I want to use before putting any effort into making jigs.

By the time I'd finish it was getting dark and it wasn't good kite weather. I hurriedly attached strings and managed to do some crash testing. This was before this photo was taken. Despite hitting the ground hard a few time nothing broke.
At 75 gram this is a heavy canopy compared to the surfer and this is exactly what you'd expect using 100 GSM sheet and thick ribs.
I think I'll try a little harder to find four mm foam before attempting a full sized (model) chute.
Cheers Eddie,

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Created by System Administrator. Last Modification: Saturday 14 of July, 2007 10:44:09 AEST by eddie.

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