During freshman year of high school I wanted to build a cannon to fire tennis balls at the highest velocity possible. I developed several early prototypes that closely resemble common “potato guns” widely available online, but wanted to do more with the idea. After much thought, design, and trial and error this is what I came up with:
– Schedule 80 PVC construction (double wall-thickness)
– Bolt action
– Propane fuel system, mixture is adjustable
– High-voltage electronic ignition system (custom-made)
– Fires tennis balls at speeds of more than 500FPS, fast enough to penetrate 1/2″ plywood
Several pictures are attached below, click the link below to see a video of it in action (including slow-motion video taken at up to 1000frames/sec):
Home-built HV source (~20,000V) for ignition. High voltage is run through three spark gaps inside of the combustion chamber to accelerate combustion rate
Fully metered propane fuel injection system: Fuel is measured to a specific pressure for optimal combustion and then injected at three different points for faster mixing. A series of small fans inside of the chamber are then activated for a few seconds to combine the fuel/air mixture.
‘Bolt-action” slide make easy loading for tennis balls, simply drop the projectile into the chamber, then slide the bolt forward and ‘lock’ it into place.