Warning: Air cannons and similar devices are dangerous. Anything you do with them is entirely at your own risk. Not Mine.

My Air Cannon

intro
This is my second air cannon. The first was made from PVC drainpipe and friction-fit joints. This had the hilarious (and partiularly dangerous) consequence of making the cannon blow itself to bits quite often. This time I wanted something I wasn't going to have to worry about quite so much so I used copper piping throughout. I don't know what the pressure rating is for copper pipe but it has to be better than PVC.

construction
The two main air chamber pipes are 22mm pipe, joined each end by various pipe joints. You can just make out the car valve in the bottom left of the above picture. The barrel is normally about a metre of 15mm pipe. It can be removed for loading, or replaced with something else.

valve
The valve is from RS Components (part number 342-023) and it also needs 2 of 342-039 to get it to fit the 15mm copper piping on either side. Although the valve is rated at 12v I've run it from a 9v pp3 battery and it seems to work fine. To fire the switch I use 2 microswitches in series, which lessens the chance of accidentaly setting the thing off!

Ammo

• Spud. Always a favourite, very effective at knocking things over.
• Water. As long as you keep it pointed upwards you can fill the whole barrel with water. Firing it gives you about 4 seconds of nothing before the water comes down again :)
• Foamy Darts. Because the barrel is 15mm pipe, the grey foam lagging tubes fit it exactly. Take about a foot of foam, cover one end up with duct tape and you've got a large scale Nerf^TM gun.

paintball

Another thing I have used the cannon for is as a paintball gun. You see those blowgun type paintball guns in the gadget shop and similar. I bought myself one from a discount shop for £5 but when me and a couple of mates tried using it we couldn't get the paintballs to burst. They would sting like hell but usually remained intact. Removing the normal copper pipe barrel from my cannon and using the paintball gun in it's place certainly changed it's power! Now the paintballs hit so fast they spread their paint so wide you can hardly see it on paintwork. It's now too powerful to point at people.