Pneumatic Air Cannon C:B ratio?

[Lokoyo]

I don't know if it's posted somewhere, so sorry if it already has.


What is the ideal Chamber to Barrel ratio?

My current C:B is 4:1 but I have a feeling it's way too big

What if there is more chamber than needed?
Would there be a drawback to that?

[Tidbit77]

technically the best cb ratios are as high as you can go, but above a certain point, the power gained is minimal. A larger chamber also takes longer to fill. For any other info, i would use the search function. We dont like to "spoonfeed" info due to the potentially dangerous nature of our hobby.

Welcome to spudfiles!

EDIT: Sorry SpudsMcgee beat me too it

[Lokoyo]

Yes I have tried but I havent been successful in finding. It ends up being about something else such as hybrids or CO2. Some of them seem to be completely unrelated to what I searched

[Pilgrimman]

I've noticed that with the search function too.... You might take a look at the wiki, though... Same info, easier to find

[Lokoyo]

Thank, that helped, but still can't find the ratio

[LCTChamp]

There is no perfect ratio. Anything above 4:1 is overkill, and the increase in performance probably wouldn't be noticeable. I usually stick with a 2:1 ratio.

[Lokoyo]

Thank very much Now I can confidently work with my plan.

Its 600 cubic inches of chamber at 50 psi. Im going to try to split the chamber into 2 sections (for 2 shots).

One will fire out of a 2" by 4' barrel (water)

2nd will fire a water balloon in a 3" maybe 4" by 2' barrel.

[SpudsMcGee]

Water balloons don't work, I've tried it before they break before they even leave the barrel.

[Lokoyo]

I might try to lube the barrel with like vasaline to reduce friction. I was thinking about that too that it would burst but I've seen it been done. Might need to do a bit more research on water balloon launchers though.

[dudeman508]

They will work in a sabou

[Lokoyo]

I rather not use a sabot because I might use this cannon in a water war.

[ramses]

I have had success with a spray 'n prey 1.5" bore with water balloons, no sabot and they went over 100 yards out of a 3' barrel, around 20 degrees of elevation. would have hit my friend, but he moved not that that's allowed here

watch recoil on the barrel full of water, don't break any tees, elbows, or shoulders/collar bones either.

I can't decide what would be worse, breaking a collar bone, or breaking a tee and having it blow up 6" away from my head.

play safe

[Lokoyo]

Is there really that much recoil from water? I forget to account for that. I have a smaller version of what I want to make now and it has a small recoil. The water is in the barrel, not being compressed.

[ramses]

FYI: for our purposes water is not compressible.

but yeah, water gets heavy. 2"x4' of water weighs nearly 5.5 lbs. that's a column of water, if you only used a foot, recoil would be much reduced. some sort of plunger might be required to expel the water effectively and not just "blow bubbles" through the column of water that is your barrel. big bubbles.

I know I saw somewhere that someone's launcher broke because of recoil. It might have been the archives. it's only really an issue in an over-under.

If you go that route(over-under), anchor the barrel to the chamber with pieces of plywood/whatever in between the barrel and chamber, and use pipe clamps to hold them securely together. brace it against the ground so as not to hurt yourself.


If you intend to use water balloons, use a slow or bad flow valve and a longer barrel to avoid smacking it with air and maintain respectable performance. also try regular balloons, they aren't made to burst easily.

[Lokoyo]

Tyvm Im planning on getting good distance and spray. Stuff like a shotgun. Do I have to really worry about parts breaking? If so, where specifically. The actual recoil itself doesn't scare me much cause I'll figure a way to adapt.