I've built combustion PVC cannons before, but I'm interested in a pneumatic cannon that can launch volleyballs at variable speeds between 5 and 40 mph, if possible, to simulate sets and serves. With a volleyball's large and slightly variable diameter (a little over 8"), I suspect it will be better to use a piston design so that I don't have to find or construct the perfect diameter tube. Anyone tried to build one of these, or have any tips that might help me out?
For so low speeds and light weight ammo you could possibly use a long pneumatic cylinder inside a larger pipe "barrel". Actuate the cylinder with fast valve, QEV or similar. It would be silent also ! Pneumatic cylinder could be bought or home made, maybe even pvc construction for light weight
If you like to build and have the tools, here is one good example (pneumatic catapult thrower) :
You could also look into pneumatic UAV launchers/catapults, they are suitable for speeds like that. Example of home made one:
