This potato cannon, or spud gun, uses compressed air as the propellant. Compressed air is much more easy to regulate and hence, can propel ammo further that their ignition based counterparts.
This guide includes instructions for making the diaphragm that controls the firing of the object.
Testing of hairspray spud guns revealed they can develop no more than 10-20 PSI chamber pressure. Most are built from schedule 40 PVC pipe. 3" PVC pipe has a burst pressure of 260 PSI.
People have suggested using other fuels to boost pressures higher, however this is much to dangerous. More volatile fuels can be very unpredictable and create pressures that would shatter the PVC pipe.
Compressed air can be regulated to exact pressures making it an excellent propellant. The trick is releasing a large volume of air at once to launch the projectile.
The monster that beats ALL other potato–cannons. Using compressed air, it will fire a potato several hundred yards. The potato will emerge at lethal speeds of greater than 400 feet per second.
An excellent, comprehensive manual on how to make the ultimate potato cannon.
Includes exhaustive parts and tools list, helpful tips, photographic illustrations to aid comprehension, assembly and usage instructions, firing instructions, technical calculations, and troubleshooting.
This is the guide to making the ultimate Spud Gun!