This is an optional step, but adding it prevents users from over-pressurizing the system to a point of failure. Thanks to aaron.linker for suggesting it! If the pressure goes over the max set on the relief valve, it will "pop" to relieve the pressure and then close again. Never allow anyone to put their face near the launch tube. Air expelled from the tube, if forced into someone's nose or mouth, is powerful enough to cause the lungs to rupture. This is very serious. Tell your students about this and they will be frightened enough to never get near the tip of the launch tube. Bachem, Erich. "Einige grundsätzliche Probleme des Senkrechstarts. Probleme aus der Astronautischen Grundlagenforschung" (in German). Proceedings of the Third International Congress on Astronautics. Stuttgart: Gesellschaft für Weltraumforschung, September 1952. Ford, Roger (2013). Germany's Secret Weapons of World War II. London, United Kingdom: Amber Books. p.224. ISBN 9781909160569.

If using an electric miter saw, we found it best to put the PVC in place, start the saw off of the PVC, bring the saw down through the pipe, and then leave the saw down until the blade has stopped. Otherwise the blade could chip the pipe. Geiger, Clarence J. History of the X-20A Dyna-Soar. Vol. 1: AFSC Historical Publications Series 63-50-I, Document ID ASD-TR-63-50-I. Wright-Patterson AFB, Ohio: Aeronautical Systems Division Information Office, 1963.Our Scout group had one of these lying around, which I very happily inherited and started playing with immediately. Of course, I tried to break it, which I did.

But please do try out different configurations! I’d love to know the best way to use the launchers.One of my cleanup tasks is to try to manage the battery life/solenoid lifecycle risk a bit better. I am not going to mangle the explanation here, but rather link to a good source on it: https://rayshobby.net/wordpress/understanding-24va... The punchline being this: "the issue is that under DC there is no reactance, so the coil’s inductance plays no effect at limiting the current" -- this observation means that the solenoids can easily overheat or burn up sending them VDC if we hold down the button too long (at least this is my understanding). A future improvement might be to add a gasket on the inside of the cap with the nozzle so that there is more support around the weak point. Jones, Andrew (26 April 2019). "Chinese firms Space Transportation and Linkspace test reusable launcher technologies". spacenews.com. Our old tubes had many usability problems (picture attached) including a leader had to hold them while another leader had to fill them with an air compressor, they were big and heavy (27in of 3in pipe, outletting to a 3/4in outlet/launch pipe), the launch was the leader holding it opening a ball valve, they were not maintainable, they were hard to store, etc, etc. Your design solves all of these problems!