Water Rocket Forum

Hi all ,

I am new to this forum and wow! so much over here. I am also quite a beginner to bottle rocketry. I have made some basic single stage rockets for local competitions and this time I am planning to make a 2-stage one.

I came across Bruce Berggren's Crushing Sleeve staging mechanism <http://web.archive.org/web/200801091226 ... /stage.htm>
It says I need a threaded lamp rod.What is it and why is it needed? And what are its dimensions? Is there any simple substitute for it in case I cant get it?
And is it ok if the solid tube from the 2nd stage fits kind of tightly in the "crushing sleeve" tube or should it be loose? Like, I have a 6mm inner dia flexible tubing. Is it ok if I get a 6mm outer dia solid pipe for the 2nd stage?

Please help me

Welcome to the forum!

scarecrow wrote: I came across Bruce Berggren's Crushing Sleeve staging mechanism [...] It says I need a threaded lamp rod.What is it and why is it needed? And what are its dimensions? Is there any simple substitute for it in case I cant get it?

Threaded lamp rod is used to run electrical cable safely through the interior of floor lamps etc. The purpose in this and Robinson Couplings is to join parts together whilst still allowing the passage of air and/or water.

Here's an example - note the material in this case is mild steel, which would not be permitted in WRA2-approved rockets, for safety reasons: http://www.thelightworks.net/index.php? ... ts_id=1146

scarecrow wrote: And is it ok if the solid tube from the 2nd stage fits kind of tightly in the "crushing sleeve" tube or should it be loose? Like, I have a 6mm inner dia flexible tubing. Is it ok if I get a 6mm outer dia solid pipe for the 2nd stage?

I think you'll have to try it and see what happens.

Hi
if you are a beginner i sugest you stay clear of 2 stage mechanisms and make bigger rockets instead, but it deppends what your defenition of beginner is of course when making two stage systems, make sure there are no loose parts and no leaks and try to make the bottom rocket as stable as you possibly can for a better 2nd stage flight check out this page i made on stability: http://www.wra2.org/forum/viewtopic.php?f=3&t=764
tell me what results you get!!!

We have discovered that large diameter surgical tubing can be used to make a pretty reliable crushing sleeve in combination with 3/8" CPVC pipe. Surgical tubing is very flexible and it has really good friction properties. We encourage everyone to try new materials and see if we can improve on existing ideas.

U.S. Water Rockets1 wrote: ↑Sat Sep 26, 2009 10:43 pm We have discovered that large diameter surgical tubing can be used to make a pretty reliable crushing sleeve in combination with 3/8" CPVC pipe. Surgical tubing is very flexible and it has really good friction properties. We encourage everyone to try new materials and see if we can improve on existing ideas.

Surprisingly, 16mm reinforced hoses work well.
It's a snug fit for any 12-13mm solid pipes, and is more resistant to blowouts.