water rockets

This was today’s project. Awesome.

This picture shows the launcher when it was nearly complete. It uses a bunch of zip ties as the trigger, the ends grab the flange on the bottle and a collar slides up to hold them in place. The bottle seals on the vertical tube because the tube has a bulge that I made by heating one ring and then squishing the ends of the tube together. In this picture I haven’t put the string on the collar, which will run down to a spool at the bottom so you can pull horizontally near the ground with a string and the string pulls the collar down to release the rocket. The rocket also has not been made at this point.

Here are some launch videos; the first is the best because we went a little overboard. The bottle was about halfway full of water and pressurized with 60 psi. It disappeared into an apex about 200 ft. up, and thankfully landed across the street in an empty parking lot.
Launch:

Recovery:

And some later launches, each with just a little water and about 30 psi. The fins eventually degraded and we lost performance:

Here’s the rocket; the nose cone is all bubble wrap (safety first):