help with first pneu cannon design

[cioeboy]

This will be my first pneumatic cannon so I have very little experience in this but I have a basic understanding (read: I have been reading the wiki and scratching my head for a few hours). It will be used for combating tanks in scenario paintball. It will be built primarily from pvc pipe primarily because my grandfather has a lot of scraps of varying lengths and sizes. I will use a 9oz co2 tank regulated down to ~80-100psi for an air source. Before I get a lecture I would just like to say that I understand the importance of checking the pressure ratings of all materials used in this cannon and I will not be using parts that are not strong enough. It will fire mini nerf football rockets.

Here is a paint rendering (not to scale) of what I will be building.



Also what is the best kind of sprinkler valve to use. I have heard rain bird was the fastest opening but I figured you guys would be the experts.


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[jrrdw]

Looks like a winner to me! BCARMS for your sprinkler valve, all ready modded.

Welcome to Spudfiles.

[psycix]

Yes, you have gotten yourself a very simple yet powerful pneumatic design.
Good for a first pneumatic.
Make sure the pipe you use is pressure rated. Especially wathc the fittings.

[pizlo]

It may be hard to wathc your fitting, but do try:)
one thing to keep in mind is chamber barrel ratios, its a very easy way to maximize your power.

[cioeboy]

Thanks guys.
As a paintball tinkerer I know all about what happens when pressure ratings are overlooked (got a few past injuries to prove it).
and like I said in the first post that picture is not drawn to scale. The chamber will be larger than the barrel but I can't make it too powerful because it must be safe enough should a player on the paintball field find them self in the crossfire between me and a tank.

[grumpy]

on a paintball field it only has to shoot at or below 230 fps, you can make it have more power if you want and it will still be field legal. you control the fps by dialing back the reg just like a paintball marker. like the others said your design looks pretty good, i would sugest adding a safety popoff valve , especialy with useing co2 and in case of reg failure.

[psycix]

It may be hard to wathc your fitting, but do try:)
one thing to keep in mind is chamber barrel ratios, its a very easy way to maximize your power.

Yes yes I typoed the c and the h.... but that doesnt matter.

But now ontopic:
C:B ratios are not much of an issue in pneumatics, a larger chamber always yields more power (wich diminishing returns when oversizing it)
The type of valve is way more important for the performance then the C:B ratio.
Bigger = more powerful, smaller = easier to fill up and has better portability.