PVC air cannons are great, and everyone should build one of these at some point in their life, but what really makes this build exceptional is the valve. [Ben] created a piston valve for this ...

Instead of trying to make an air-tight piston, he added a rubber membrane and a clever valve system to create a diaphragm air engine. This GIF is worth 115 words A round rubber diaphragm with a ...

Both rotary engines and piston engines utilize internal combustion ... Later designs of the Mazda rotary engine included two more valves for greater air intake when needed at higher RPMs.