An air cannon capable of propelling a 1/4" ball bearing to supersonic velocities.

I built this project in August of 2021 after experimenting heavily with air powered cannons using different valves capable of firing at various pressures such as ball valves, quick exhaust valves, and safety release valves. The working mechanism of this project is a hydraulic ball valve being rapidly opened by rubber speargun tubing. HPA from a 4500 psi cylinder is regulated down to 3000 psi into a fixed volume chamber. The chamber is filled then sealed off from the rest of the tank after the ball valve has been closed and the cannon is loaded. Upon pulling the trigger, the valve opens rapidly where the high pressure air travels through a 3D printed converging-diverging nozzle to allow the air and thus the projectile to reach supersonic velocities. Some parts are designed in SolidWorks and then 3D printed such as parts of the frame and grip. Due to the very high operating pressure, all fittings used are made of carbon steel and rated for at least 3000 psi. The maximum recorded velocity, as can be seen above in the picture of the chronograph reading, is 372 m/sec or 1220 feet/sec, above the speed of sound at around 1150 feet/sec where the cannon was shot. The projectile can be heard breaking the sound barrier in the video below.