The Rare Norm a couple of months ago Share Tweet Pin Share This used to be a Science Olympiad event. Look up Water Bottle Rockets, you can probably still find a ton of materials on how to do it. The simplest design is just a single bottle with fins tape to the tail and a cone stacked at the top, attached with kite strings and tape (use tape to attach everything to the bottle, don’t puncture the bottle). You can fly a lot better than the gif with just a single bottle. Those guys are overdid it for little to no gain in performance. I think the standard pressure to use for the competition was 60 PSI, you can probably start lower to be safe. It’s easy, middle school kids were doing it, so don’t get discouraged.