As huge fans of water rockets, we are worshipping Australian rocketeer George Katz and his Air Command Water Rockets team, who are now launching single-stage soda bottle rockets over 600 feet using three drop-away booster engines that separate, NASA-style, when their thrust is spent. The boosters have upward-pointing pins that slip into rings on the main rocket, so they simply slip back out upon burnout.
To make it work, the team devised a clever launch base with an air manifold that pressurizes all three boosters equally, simultaneously with the main rocket. Air Command’s insanely good website has video of the launcher build, DIY instructions for drop-away boosters and all aspects of water rocketry including multi-stage and parachute mechanisms, plus build and flight logs for all kinds of crazy rockets. And their launch videos (from ground and onboard cams) are so awesome we want to build a water rocket Cape Canaveral.