My piston Design

[L.J.R]

Well I have been browsing these forums for a while and finally decided to join. I've made one air cannon already that uses a sprinkler valve it was designed for home made darts. Well for my next cannon I wanted it to be something special so I opted for a piston valve, I haven't seen any piston valves that have the flow that I want and can still have a breech loading mechanism. For my new cannon I wanted it to have a very high speed around 850 to 1000 fps though I’m thinking that might be a bit too ambitious though. The bore of the barrel would be somewhere between 0.20 and 0.35 cal. I was thinking it would e easier to achieve those speeds with a smaller barrel. I plan to make it out of either PVC or Copper I’m leaning more towards PVC for the ease of construction and cost. So here's my plan for the valve I think I spent more time drawing than I did planning it. I know it has problems but that's what i'm hoping you people can help me with. The picture is fairly self explanatory, i hope it's big enough for people to see it clearly.



thanks

[frogy]

That's just a run of the mill barrel-sealing Tee with a spring behind the piston, it's been done many many times, your picture is very very small though nice design...

I like those type of guns, but you'll notice they're harder to make than to draw

[Shrimphead]

You are probably going to want to make the sealing end of the piston bigger in diameter. The bigger that is, the more force will be on it and the faster it will open.

[L.J.R]

Cool, I'm glad it'll work it's in the designing stages so it will be a while before I start to make it I just wanted to make sure it would work, thanks.

[L.J.R]

You are probably going to want to make the sealing end of the piston bigger in diameter. The bigger that is, the more force will be on it and the faster it will open.

I was thinking that the smaller the barrel sealing section the better. I figured more force will be on the front part of the large section of the piston. I don't really know hopefully someone can tell me different or explain a better way to go about this.

[CS]

If your barrel is a fixed size increasing piston diameter will decrease seating pressure, while slightly slowing opening time since a larger amount of air must be vented.