PCP Calculation - Please assist me

[joaquin]

Hello guys,

I am building my own PCP home made gun from parts (paintball tank+ plumbing parts) but I have one big question at the end and I need one of you experts to help me out cos my physics level is equal to zero and I can't solve this.

My setup:

Paintball tank (pressure 3000 PSI) ---> regulator (regulates the air going out of the tank at 850 PSI - classic pressure for pinball guns) ---> sphere valve ---> "loading cylinder " (dunno how to call it, but it is a piece of pipe that the regulator will fill with 850 PSI pressurized air) ---> trigger valve ---> 13 mm inner-diameter barrel (50 cm or 60 cm long i haven't decided).

That s the whole project.

Now my big question is:
- if i decided to try and shoot a 12.5 mm carbon steel bearing ball as ammo, what volume (cc) should my "loading cylinder" (as i called it) have in order to be able to get a decent performance out of this PCP setup ?

I want to thank you in advance to any of you knowledgeable people that can solve my physics problem! Cos I think that is pretty much what this resumes to. Looking forward to your answers!

[Copperboy]

Hi Joaquin!
May i suggest the program called GGDT (gas gun design tool)? I'm sure you'll find it if you look around, should be on the spudwiki as well.

Its a program for just this purpose, fiddle around with it until you find the power you're satisfied with.

[matti]

You are balancing between muzzle velocity and shots per tank here.. you need to think which one is more important for your use. If you can get the paintball tank filled easily and cheap then you could go for larger chamber etc.

Your valve will make a big difference too, I would go for small volume chamber with a very fast valve.

Here is calculator that you can use to figure how many times you can fill your 850psi chamber from the 3000psi bottle (test different volumes to see what kind of difference it makes)

LINK: https://sye.dk/airgun/

And GGDT is good for testing different configurations of barrel lenght/chamber size/pressure if you learn how to use it (it's quite simple)

LINK: http://www.thehalls-in-bfe.com/GGDT/