A jam jar pulsejet engine is a simple yet fascinating demonstration of reactive propulsion. It works by igniting a fuel-air mixture inside a jar, usually methanol vapor mixed with air, which rapidly combusts and expands. The expanding gases rush out of the opening, creating thrust, while the sudden drop in pressure draws fresh air and fuel back in to repeat the cycle. This repeating cycle of ignition and refill happens many times per second, producing the distinctive pulsing sound that gives the