How to Build a Water Rocket Launcher

***  This post is from an earlier time.  It has been unearthed and placed here for your amusement. ***

The Great Mazinga

Earlier this month while visiting family, I built a most wondrous toy with the help of my relatives. Using some PVC pipe, a tire valve stem and a few other parts we created an apparatus capable of blasting a 2 liter soda bottle a couple hundred feet into the air. Children laughed. Adults squealed with delight. Dogs barked and ran in circles. Even the neighbors had to come and join the fun once they saw what was going on.

You can find links to step-by-step construction videos here.

There are numerous ways to build such a device, but I really liked this design for its safety and simplicity. The bottle it is kept above head height in the highly unlikely event that it ruptures. The person doing the launching is in the direct blast of the thruster water which is hilariously good fun. The locking mechanism is extremely secure and much better than the designs using quick-release garden hose adapters.

Here is what I changed:
1. Lengthened the 1-1/2” diameter pipe on the trigger from 2” to 3”. The longer this piece is the less likely it is to bind. It isn’t a safety issue but helps prevent a potential annoyance while reloading the device.
2. Used 1-1/2” diameter pipe for most of the launcher instead of ½”. This is done to keep the launcher from bending when a big heavy water bottle is perched on top of it, plus it looks cooler too.
3. Shorten the overall height to just under 7 feet.  If you use a second-stage cup that fits on top of the bottle to hold a water balloon, you’ll need a step ladder to load it with the original design.

Side View

NAME: The Great Mazinga (picture)
PURPOSE: To guide a 2 liter payload heavenward and safely return it to Earth
COST: ~$15
NOTE:  For maximum fun, an air compressor rather than a bike pump is recommended.

Bring on the water! Bring on the pressure! Bring on the fun!


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