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Second Cannon

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: CYANIDEGENOCIDE » Tue Nov 04, 2008 8:05 pm

Ragnarok is correct and incorrect. I didn't change the valve stats, because I don't know them, I would lean more toward his estimation in that respect. I definitely misunderstood something in the inner and outer diameter of the chamber (why would the program ask for outer diameter??) I used the outer diameter of the 4" pipe, but what "outer diameter" is it asking for?
The only part of his post that is incorrect is the mass of my projectiles, I have been using the plotter paper tubes from work since they are 2" inner diameter, I cut them up and fill them with concrete and rebar. I have a pic here somewhere. After it cures I soak them in water to take off the cardboard, then I coat the outside in newspaper soaked with vegetable oil. I have them in several weights 1, 2, and 4 pound increments. The 2 pounders give the best performance, 2.2 pounds per kilo right?
Paintballs through sheet metal!? I needs me moar velocity!
Um, gunshows usually have flechettes, "shotgun news" magazine has them. The nutty militia type gun stores can probably get them for you. They don't serve any real purpose except death and mayhem, so its not something you will find at walmart, sorry.
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Unread postAuthor: Ragnarok » Tue Nov 04, 2008 8:23 pm

CYANIDEGENOCIDE wrote:I definitely misunderstood something in the inner and outer diameter of the chamber (why would the program ask for outer diameter??) I used the outer diameter of the 4" pipe, but what "outer diameter" is it asking for?

- Outer diameter is the inner diameter of your chamber pipe (the OUTER pipe)
- Inner diameter is the outer diameter of your barrel - in the case you are running your barrel through the chamber (the INNER pipe), in a configuration known as "coaxial". If your barrel doesn't go through the chamber, set this to zero.

It's somewhat counter intuitive at first, but you fast get used to it.

Paintballs through sheet metal!? I needs me moar velocity!

You can use water jets to cut through brick, rock, and steel - anything that gets fast enough will go through anything else.

What takes a lot of velocity is when the projectile stays in one piece.
It's most obvious with something like grapes and corrugated cardboard.

Try pushing the grape through the cardboard - it squashes. Fire it at a couple of hundred fps, the grape goes through. Get a bit faster, it goes through in one piece.
Get faster again, and it peels itself in the barrel - oops.

Well, actually, in that case it's because I use short barrels and higher pressures - which creates accelerative forces the grape can't take.
A longer barrel and milder acceleration would be a fix, but that's not what I do. :twisted:
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Does that thing kinda look like a big cat to you?
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