Fully Automatic Pressurized Air Cannon
This was an experimental attempt to construct a fully automatic potato cannon. The firing action is controlled by a microcontroller which, upon detecting that the button is depressed, opens the rear valve to allow air into the secondary chamber (rear half of the cannon) from the tank. (on the ground, connected by a hose) After .75 seconds, the rear valve is closed and the front valve is opened for .25 seconds to fire the projectile. It then checks the button again, and if it is still depressed repeats the process. All the user needs to do is hold the trigger.
The purpose for this dual valve system is to fire a fixed volume of air regardless of the pressure. As the cannon fires each shot, the cannon loses some of its pressure. Without this fixed-volume system, volume would also decrease, which would cause the cannon to lose power significantly faster.
In theory, this sounds just peachy, but in reality the loader has proved to be extremely unreliable. There is no mechanism to prevent the balls from rolling out the barrel. Furthermore, the loader is extremely unreliable, sometimes firing nothing, sometimes firing 2 rounds at once.
The power, however, is more than I had expected. I attribute this to the use of plastic projectiles which have essentially no friction in the barrel. To test this, I should fire a F.A.P.A.C. projectile out of the P.S.C. to see if that manages to acheive such velocities as well. However, I have not due to safety concerns - even the F.A.P.A.C. managed to shatter a round when fired at plywood. I can't imagine what the P.S.C. would do.
The wiring is extremely delicate and breaks upon the slightest trauma. I finally got sick of fixing it. The F.A.P.A.C. is currently out of order due to electrical problems.