Mega cannon

[PiperChris]

I posted a while back about some pipe I got for free from the local high school redoing their drainage field. I originally thought I was going to make a combustion cannon but after reading up, I want to make a more powerful pneumatic cannon. Here are the supplies I have:
1- 10 foot; 3 inch pvc pipe
1- 10 foot; 4 inch pvc pipe

What do you suggest I use for valves and other parts I might need? I'd like to keep it as cheap as possible (I'm a poor college student haha) while retaining the most power (aka the best bang for the buck, no pun intended)

Christopher

[fullmetaljacket]

What's your budget like? A combustion is definitely the most economical way to go, especially as you scale up.

I think a burst disk valve would be the cheapest and most effiicent solution if you still want to go pneumatic.

[PiperChris]

I'm hoping to keep it under $100 but if I can keep it under $50 then that would be even better!

[sgort87]

You could always use a <a href="http://cgi.ebay.com/New-One-3-PVC-Ball-Valve-SxS-NR-Valves_W0QQitemZ330060412915QQcmdZViewItem">huge PVC ball valve</a>.

[fullmetaljacket]

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">You could always use a <a href="http://cgi.ebay.com/New-One-3-PVC-Ball-Valve-SxS-NR-Valves_W0QQitemZ330060412915QQcmdZViewItem">huge PVC ball valve</a>.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

That would work, though you'd have to attach some sort of lever or a hefty spring for rapid actuation - a 10 foot barrel will give you enough acceleration, though it would have to be secured in place otherwise you can forget about aiming.

[PiperChris]

Would something like the Supah Valve or a Mauler valve be better than that PVC ball valve? Sorry for all the basic questions, I'm quite new to pneumatic launchers.

[sgort87]

Yes they would be better but Supahs are not being sold at this moment and I am not supposed to advertise my Maulers on other forums. Feel free to look into them, but I won't be talking about them on Spudtech.

[PiperChris]

I understand.

[InvisibleAndThenSome]

Drainage field? I smell DWV. Make sure before you build anything that the pipe you have is rated to the pressures you want to run.

Unless you have a lot of tinker time, a ball valve just might be a better approach than trying to make a piston valve. Either way, you also might want to think about having threaded fittings so you can change out the valve or barrel.

If you do decide to build a piston valve, there are tons of tutorials all over this forum, on http://www.spudfiles.com and other websites. Let your fingers do the walking.

[PiperChris]

No, It says on the pipe:
4" PVC well casing

It also says it's rated to 200PSI

Is this safe? I'm only planning on taking it to about 100PSI.