Compressed Air Cannon

[Wrist Pin]

Had this idea while reading another thread.
Does anyone have any plans for building a compressed air cannon?

 

[Entropy455]

What is the purpose of an air cannon?

Is it to fire projectiles? Or to make a big noise?

Firing projectiles could be fun, but you’d need a nice size energy reservoir.

I’m not sure an air powered cannon could compete with black powder in the nose making category.

I have seen smoke ring cannons, and they are VERY cool.

 

[jor2daje]

I've built my fair share of air powered cannons you should check out www.spudfiles.com they have some amazing stuff. What material are you looking to construct it from, Ive built them from pvc, copper and brass. The best design I have seen so far is a coaxial piston valve, heres a basic diagram of how it works.

basically air pressure from behind forces the piston to seat against the barrel port, then when air is released from behind, pressure acting on the front of the piston opens it very quickly.

Heres a simple diagram I made for constructing a cheap piston valve from pvc plumbing parts, although since youre on a machinist forum you are most likely capable of much more than the average spudder.

these principals can be applied to pretty much any scale and material. The piston can be made more efficient by using a floating oring seal to prevent any air escaping out of the pilot.

heres the cannon I made, its 1.7" calibre for shooting golfballs, according to a computer simulation should put a golf ball about 500 yards though I have never been able to test it

 

[jct842]

I saw a small one demonstrated that would send a golf ball out of sight. it was about2 feet long and used the design above. it was power by 900 lbs of air. it was at the little rock air rifle show 3 or 4 years ago. all metal and was not very big in diameter. they filled it with a scuba tank. john

 

[Wrist Pin]

Ingenious jor2daje!!!
Thank you! I will visit that site and put this on the "list of things to make"!

 

[Rocket Man]

I have built some air cannons but I have no plans. I like to build things from EMT conduit and Muffler Tubing. Find a piece of 4 ft long tubing that a tennis ball will fit in. Then weld a 1/8" diameter ring up inside the tube to block the tennis ball. Slide in the tenns ball, screw on the back cover, turn on the air. The ball is blown up against the 1/8" ring but can not get through. As air pressure builds up it finally forces the ball past the ring. The 12" air space behind the ball acts as the air supply and blows the ball about 400 ft. If you make the 12" air space larger the ball will go 700, 800 or more feet. A tennis ball is too light weight to go very far.

I can shoot a base ball about 1/4 mile. It usually blows the outside cover off of the ball. I am using a propane/air mix cannon. The barrel is 4 ft long the combustion chamber is 8" diameter 10" long.

I shot a golf ball slightly over 3 miles once from a place where the Wabash river curves. I shot it the length of the river with several spotters along the river bank so we could see the splash.

 

[Wrist Pin]

Wow, Rocket Man!
That's about as simple as it can get! Powerful too!!

 

[Ed T]

I think the principle shown in the fine illustrations from jor2daje are very similar to those used in a nail gun. Take a look on the how stuff works site for more info.