DotFisk

Now that I have finally come up with a relativly easy method of butt joing bottles, I sat down this weekend and made another two butt to butt joined sections. I have that it is extremely important to make sure that the holes in the bottom of the bottles are perfectly central, otherwsie the ridges on either bottle will not sit together properly. This will in turn mean that the actual centre of the bottles are not touching and thus your little piece of threaded rod, will not be long enough.

Now that I have 3 completed sections, I can start to construct the bottom half of our new rocket, which will be a booster cluster comprised of 3xrockets. For demonstration purposes I have held the 3 sections together with elastic bands.

You can see I have placed the staging mechanism on top of the boosters. There will probably be another section inetween them, which contains the electronics and parachutes for the booster section.

After trying many times to get a working air tight pressure switch using the brass components in the previous post, I decided that it wasn’t going to happen. So I set about trying something new.

I stumbled across this on the Yahoo water rocket forums:-

http://groups.yahoo.com/group/water-rockets/photos/album/930791471/pic/list

I decided that this looked like a very reliable method of making a pressure switch. The only down side is that it needs to screw onto the top of the bottle, this means that you need to join the bottles together by bottoms, instead of the normal top to bottom arrangement.

I am glad to see, as you can see below that the new switch works really well and there is no sign or any leaks. The switch operates at about 20psi, slightly higher than the previous design, but probably due to the slightly thicker rubber.