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Hi everyone, I'm new to air cannon building and I was hoping that I could get some good input on my design. Although I do have Inventor on my computer, I'm new to it as well so I'll try to describe it to you the best I can. So this cannon needs to accomplish a very specific goal because It will be used in Milsim airsoft games as an RPG since I am my squad's combat engineer. Aesthetically, it will look like a Carl Gustav launcher. It will need to shoot a nerf vortex ball/missile at least 100 feet and will operate off of compressed air. Here's the catch: I want at least three shots before having to refill the air. I plan to hold the air in a used fire extinguisher cytlinder at about 100 psi. The cylinder is linked to a pneumatic quick release with a male and female end like what you would find on a pneumatic tool and hose. This will allow for quick cylinder changes. This links to a pressure gauge and then to the first ball valve. After this ball valve there is a 5"longx3/4" piece of pipe followed by another ball valve. The two valves will act as a primer and release therefore giving it multi-shot capabilities. After this chamber is the barrel of the gun. The biggest draw back I think is that after each shot, the overall psi will decrease significantly. Do you think that I would still be able to attain 100 feet with each shot? I appreciate any input.

In terms of performance, something like this will give you the performance you're after: http://www.spudfiles.com/forums/second- ... 14735.html



As to making it a multishot, look into slide valve piloting for the valve instead of the blowgun in the example above:
http://www.spudfiles.com/forums/semi-au ... 23626.html

The idea is that you have two chambers, a main reservoir and a firing chamber. If you're worried about consistency, you can have your main chamber at say 150 psi, then connect it to the slide valve via a regulator taking the pressure down to say 60 psi.

There are other alternatives you might want to explore, such as a preloaded cartridge - you can make several and they will always give you the same performance. Here's one way of making them:



If you're allowed a combustion launcher, they can be even simpler, just a tube closed off at one end. Imagine something like this, that can be loaded into a breech: http://www.spudfiles.com/forums/clear-c ... 22067.html

If you want to stay pneumatic and go even simpler and high performance, go valveless



In short, there are many solutions to your specifications. What you chose depends on the extent of your technical abilities, material and tool facilities and budget.