Air Cannon Construction

[Theophrastus]

My friends and I were thinking of building an air cannon, to play around with motion equations, and secondly, to have a blast by utilising it in various ways. The conceptual idea is pretty simple, a cylinder of pressurised air, connected by a butterfly valve to a relatively long, rigid PVC tube, which would act as the main barrel. We were then thinking to then mount our settup onto a a flat wooden base, and then simply add an axel, on which one could regulate angle. As I said, the idea's simple, but I thought to ask some more experienced members here, for perhaps some hints in regards to how to achieve optimum performance. Any thoughts?

[Cap'n Refsmmat]

I'd suggest using a design like this:

http://www.instructables.com/id/Air-Powered-Potato-Cannon/

 

Just read the comments on some of the steps on what materials would be better (and safer) to use -- some of the commenters point out that the PVC used isn't strong enough, and so on. Other than that, you can probably scrounge some good ideas from it. With a good pressure gauge and a protractor for measuring angle you could get very consistent results.

[InigoMontoya]

Ah.... Air cannons: My primary hobby.

 

First, the instructables link listed above (if followed) results in a pretty pathetic air cannon at best.

 

Butterfly valves can be OK.

 

But what you really want is some sort of QEV or pulse valve. That said, how big of cannon are you interested in making? If reasonably small, you would do very well by going to mcmaster.com and picking up part number 6646K23. They cost about $25 and are lightyears ahead of virtually anything you'll manage to cobble together on your own in a first cannon(*). If larger, Asco valves makes some "dust collection pulse valves" that are very impressive (and a bit expensive if bought from Asco but they can be found on ebay for significantly less).

 

In addition, there's a piece of software out there called GGDT (Gas Gun Design Tool). If you've half a clue, it will predict performance of an air cannon to within about 5% before you ever build it. Just google for it.

 

Finally, probably the best resource on the net for air cannons is a forum called spudfiles.com. There's other stuff there, but look for the forums. Like any forum it has some clueless folks on it, but it also has some extremely talented people there. Pay attention to them and you'll learn what to do (and more importantly what NOT to do) before you even start shopping for supplies.

 

 

 

(*) Yes, better valves can be made, but I'm talking quick & easy here.