So if it's not an issue, how come so many people note the fact that CO2 has a lower velocity potential than air? Unless I'm using ultra-light, neary weightless projectiles (or, like you say, use unreachable high pressures) the determining fact for velocity should be pressure alone and not gas ...

JSR: So using CO2 cartridges is not a real option after all, if more than 200psi behind the disk of such a launcher is too much, is it? The cartridges have more psi....

saefroch: yeah, you're probably right about that. Wouldn't even know where to start shopping though, for example to connect that ...

Is the silver bottom device the pressure chamber? Where can I get sth likes this, e.g. what is its original purpose?

I found a shock pump up to 21 bar... is that enough? Much less than CO2 cartridges...

That handle is from a high-pressure cleaner, right?

PS: Man, you are really quick in drawing ...

So then it would make sense to design such a launcher in a way that there is a pre-chamber before the "real chamber" with the burst disk and have pre-chamber and real chamber connected with another valve. that way it is possible to let all the CO2 flow into the pre-chamber, letting all CO2 boil ...

Yep, that's exactly my point!

Dunno if it's true or not. From the wiki article you get a different impression, but this may only be valid if there is no (more) liquid CO2 left or has never been there in the first place (= lower cartridge starting pressure).

Yes, I know that.

My point was referring to what another member said earlier, that an increased chamber size will result in a lower pressure and therefore lower velocity. I think a bigger chamber will result in an unchanged pressure thus higher velocity, as a part of the liquid CO2 turns to gas ...

Cool, this one looks better than the first. Thank you!

Something else came to my head.

To Saefroch: You told me that a bigger expansion chamber (using the same pressure source) would not increase the velocity of the mentioned launcher, but lower it instead. The reason would be that the amount of ...

In your model you selected "air", which I guess should be changed to "CO2" for a start. But I'll go and figure out the functions of the program myself.

Thanks also for your subtle hint (the one telling me to look down the barrel of a ready-to-shoot launcher). I'll make sure to follow it, but only ...

Wow, again most helpful replies folks :-) Thanks esspecially for the design suggestion - nice naming of the .png file also :-D I think I will build just that. Is it drawn in the right dimensions/relations?
Furthermore, apart from the valve really no steel is needed?

When using the burst disk the ...

Then why does the guy who constructed this launcher state:

"If distance is really a concern making the expansion chamber tube longer will add some distance but lowers the portability."

?

Source: http://www.houndsofhellpaintball.com/articles1.html


Trying to understand how this launcher could be ...

I see, you all have really helped me to understand what this is about. I will download that program and play around.

One last thing. You all know this version I suppose:

http://www.youtube.com/watch?v=jsXd8yu9wq8

Since a 12 gram CO2 cartridge is used, I was surprised that the velocity seems ...

First and foremost, I'm talking about bar, not psi. The handpump I was referring to is really capable of building up that pressure. And I really won't to stick to pneumatic here and not go hybrid.

Other than that...

Saefroch:

I came up with my third question because of Ragnarok's statement

"air ...

I understand. So, what does - in average - have the bigger effect on velocity? chamber size or pressure?
let's say: what is more powerful? a 1000ml chamber at 5 bar, or a 500ml at 10 bar?

is there any default limit for the chamber size? e.g. saying it should have a minimum size of x ml to be ...

I see, thanks a lot for your answers. That really makes sense, I also wouldn't even know what kind of materials to use for 200 bar, not speak of valves...

Saefroch: By "efficient" I meant velocity. Also, can your please elaborate your last point a bit more? If I got it right, then with an efficient ...

Okay, so high performance spudguns don't need that high pressure, but... wouldn't higher pressure make them even more efficient?

Looking at a "typical" pneumatic launcher, powered by "normal" air with a handpump and, let's say, a golf ball caliber.

why is it spudguns like this would fire with ...