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Water rockets! Who doesn' t love them. Cheap, easy, safe, fast....


Does any one know an easy way to fire a water rocket? Some mechanism?

Rubber bung + football inflation spike.

Heat a nail to red heat with a blowtorch (hold it in pliers!)

Push the nail through the bung, pull it out and immediately push the inflation spike through.

When the rubber cools and sets, it will make a good seal around the spike.

Fit the spike to a footpump, wedge it in the rocket, prop the rocket up on some bricks and pump!

When the pressure gets high enough to push the bung out, the rocket will go.

You get wet, but it works.

That's just like mine except using a valve for any truck/car rim will always be easier (make damn sure to remove the valve core, they usually come with them in but taking them out involves five seconds of screwing)

would steam be a good propellant? like the steam machine gun in mythbusters that cranked out pretty good, or is liquid H-2-O better

uses compressed air usually, steam might work but would be a waste of time and effort for the same results (unless the bottle gone soft under heat then you'd be blowing a massive plastic bubble...)

Yes I would agree, all except the "safe" part... be very careful as
common sense isn't all that common these days. Someone could take you literally... Low PSI water rockets would be considered "safe". But "water rockets" is a broad term encompassing many style and pressures, many would not consider these "safe" by any means especially for the un-initiated to the power of compressed air....

Rant over.....

Do you make your own or purchase them.? Either way they are awesome and majestic as well.

Ummm the valve idea i mentioned in the comment that's likely to be directly below this is perfect for that problem of the uninitiated, drinks bottles are safe to at least 80psi (lowball) the valve is forced out of the neck at less than 60psi when dry it's pretty safe that way...

To be honest any one who has ever bought a commercial water rocket has wasted their hard earned cash. You could even buy a cigarette lighter adapter compressor, a few truck rim Valves and a bottle of fairy liquid for £25 which is the amount I saw several competing kits for. With these things you can fire up to 3L bottles pretty far pretty fast, only problem is aero dynamics... Wait use the box from the cheapo compressor... and yes even the ones on the jumper kits are enough to launch the rocket... The only great thing about the commercial kits are the quick release launcher adapters, but these aren't self regulating... Like the truck valve trick, also you can fire as many bottles as you want before retrieving them as the valve stays on launcher.

Do a google for Clark Cable tie Release, muy awesome, lets you get up into the higher pressures.