My friend Barney pointed out this web site : adaptaflex (click on 'plastic components' and browse the selection of 10mm stuff), these guys make plastic bushes for electrical cable protection. The cable goes through the center of a threaded plastic tube.

I nearly fainted with joy.

I got hold of some of these bushes. They worked great after quite a bit of modification. I trimmed all the excess plastic with a knife and made some washes from old CD's and glued a rubber backing to them. This was then assembled with plenty of glue onto the bladder.

These turned out to be really light, strong and airtight.

But...

Because of the plastic material that the bush is made of, the pump would not 'stick' to it. As soon as I tried to inflate the bladder the pump would slip out and it would deflate. I tried sticking some rubber inside the valve, this worked ok, but some air did leak through the seam in the rubber.

The aparatus that I made did not have a valve in it, so as soon as I took the pump away from it air rushed out. This was fine for the larger bladders as the amount of air the escaped was a small percentage of the total air inside. But for the smaller ribs, they went floppy as soon as the pump was removed.

These two problems forced me to rethink the whole approach. I wanted rock solid bladders.

The actual inflation of the bladders had to be easy. If it was a pain in the arse then I'd never bother to fly the kite, I mean, I have a perfectly good AirBlast, why fart around with a home made kite when you could be in the water?

So the next big experiment was with kiddies inflatable arm bands, cutting the valves from these and glueing them to my bladder material.

Initially this worked really well, so long as a lot of glue was used. The test bladder stayed inflated for a couple of days. So I built one for the kite, using liberal amounts of glue, let it set for an evening and tested it. This one worked as well, so I inserted it into the Dacron sleve, and as I pushed it thrught the small opening, all of the glue stuck to it's self and the bladder glueing it into a small ball, the bladder was useless.

So I need to let the glue dry better, and perhaps add some talcom powder inside the bladder to smooth the sticky spots.

I also found this website that sells bladders, airtimegear. That'll save you some time and effort!

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