I don't want to get into the fine details of actually making one work but the power is certainly there. A 2" bore pneumatic cylinder pushes with about 180+ pounds of force. Since work is force x distance you can multiply that out. (180 lbs of force * 9 inches of travel) inch pounds in joules is according the Google calculator 183 joules. Thats a ton of energy! I'm not sure if thats exactly how a pneumatic cylinder would translate into energy but its got to be considerable none the less. As was stated above a pouf ball needs about 13.7 joules to to go at 12 m/s(instead of the 18 joules for a single flywheel design due to the spin). That means that a 2" bore pneumatic would in theory only have to travel about an inch or two to put enough energy into the ball assuming a pretty thorough transfer of energy and a very light throwing arm. Just some numbers to think about. I'm still sticking to a fly wheel.
