Theoriginalllama puts up a demo video of the Electromagnetic HPA Engine Prototype that he has been developing... "Quick demo of the coil working on the first physical prototype of my new engine design. It uses an electromagnetic coil to actuate the nozzle, and a solenoid valve to fire the gas.
Hit a problem that the coil isn't yet strong enough to work with 11.1V batteries, so I need to make some design changes! This demo is with two 3-cell LiFePO4 batteries in series (about 20.5V)."