New Launcher

Posted: July 21, 2011 in Uncategorized

Just finished putting together the new launching mechanism. This time the bottle release is based on a Hozelock/Gardena style hose connector.

Starting from the bottom right:

Same Schrader valve as before, this time in a 15mm pvc pipe end cap. A length of 15mm pipe is then connected to some re-inforced hose line (rated to 144 psi) and held in place with a jubilee clip. Oh, and both ends of the pipe have pipe inserts fitted to them – these strengthen the end of the pipe and prevent it collapsing from the pipe weld glue (which melts the plastic a bit) and the force from the jubilee.

The hose is then connected to a B&Q own brand hose connector with quick release. This is modified slightly, detailed below.

On the left I’ve connected a piece of coat-hanger wire with a jubilee clip to the release mechanism. The launch string will be attached to this wire.

On the right is the view down the barrel of the connector. I had to dismantle it and sand a couple of millimetres off the internal fitting to allow the bottle connector to lock in place properly.

Also these hose connectors have a no-return valve in them – basically a plastic stick with a washer to make a seal. The idea is that when you disconnect your spray gun or whatever the water flow stops. Unfotunately this is the wrong way round for a water rocket – I want to stop water going into it from above. If you remove the washer from the valve the plastic slides out, so I did that and refitted the valve the other way round. Hopefully it will stop the piping filling with water, although I haven’t tried it out yet.

 I’ve pressure tested the seals to 40 psi so far and everything has held perfectly.

Finally onto the last part of the setup, the bottle connector. This is made from a tap connector that’s designed to lock into the hose connector. I took off all he excess plastic using my dremel so that I was left with just the locking part and a tiny bit of shoulder. I’ve fitted this into a standard bottle top and glued it all up so that it makes a good seal. The seal wasn’t perfect, but a few wraps of PTFE tape round the threads on the bottle and it’s leak free.

Now I just have to mount it onto the wooden base and it’s time for some test firing!

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