best ratio for a ball valve gun

[spudzooka98]

hello im making a pneumatic gun its going to be on the smaller side but i need to know a good ratio for a ball valve please no "dont use a ball valve" its all i got its hard to get things when your young and parents dont understand your passion for spud guns but the barrel is 24 inches of 3/4 pvc what do you guys think will be most effective thanks

[Zeus]

Between 1:1 and 2:1, really doesn't matter.

I'm sure a handful of 1" fittings and a 1/2" ball valve wouldn't be hard to get, then you've pretty much got a piston valve.

[spudzooka98]

can you explain the piston valve

[Technician1002]

Part of the ratio would be influenced by the choice of projectile. Due to the slower speed of the valve, they work best with larger heavier projectiles. If your projectile fits well and seals the barrel, you can use a smaller chamber. If your projectile is loose fitting, such as a soda can launcher, then to compensate for air lost to blow by, a larger chamber is recommended.

[jsefcik]

can you explain the piston valve

look in the wiki =)

[spudzooka98]

im lookin it up in wiki right now also should the camber diameter be larger that 3/4 inch or is that fine

[ramses]

If possibly the chamber of the launcher should be high pressure low volume. That will allow a higher mass flow rate through the partially open ball valve (greater density at the same speed and area). Light projectiles will be more significantly affected

As to explaining the piston valve, there is a STICKY in the pneumatic cannon discussion section called 'piston valves explained visually' I will not link to it on principal.

You will find that people are much more willing to help you when the answer to your question is literally on the page you visited to ask it.

Should you try to use the search, there is another sticky that explains how to do so effectively. The quick search at the top of the page is just total crap.

[spudzooka98]

thanks yeah ill look for that thread and yes i know how to use the search but it keeps saying cant search so soon after the other one or something like that and what do you think of wrapping the gun with camo duct tape