SpudFiles

On Saturday I tried my last idea to get my burst disk cannon to seal properly without spending large sums of money. This idea failed. Consequently, you won't be seeing the Uber-powerful burst disk gun until January at the earliest.

This setback reduced me to only a single operational launcher, my first spray'n'pray combustion, which isn't really that satisfying to shoot. I wanted a launcher that was both fun and easy to shoot, as well as being handheld and having fast reload times. I also wanted to use the nitrogen tank that costs me $56/year for something other than decoration.

I came up with this design, and put it all together on Saturday afternoon.

Specs: Chamber: ~51 inches of 1.25" steel pipe (actual ID is 1.38")
Barrels: 1.5"x 4'
1.5"x 12'
Barrel material: ABS (what else?)
Firing Valve: 1.5" brass ball valve, rated for 600 psi
Fill valve: hydraulic quick connects, rated for 3000 psi (!)
Pressure source: type 16 industrial nitrogen tank
Operating pressure range: 150-500 psi

So far, I've only pressurised it to 400 psi, at which point it soon developed a leak. There are two clips on the video of it firing at 400. The 12' long barrel greatly increases performance, but severely cripples ease of use.

As far as range goes, after 150 psi you can't see the potato at all. Estimated range at 150psi is about 150 yards, if not more. This is with the short barrel.

[youtube][/youtube]

Nice Gun!

Though, the barrel seems like it needs more support.
Is the Filling tank one of those tanks that ou have to take back to the shop and they swap you one?
Happy Spuddin'

The barrel just looks like that because of the angle of the picture. The filling tank is one of those ones that you take back to the outlet, where they send it away and hope to get it back in about a week, and then charge you $20 more than they said they would.

Are you still trying to make that cannon that you want to create a sonicboom with (surpass the speed of sound). Cause that is something i was looking forward to. But nice gun for now, just need to change that brass ball valve with anything better

Sweet cannon man! Are you renting the tank?

Damn nice looking cannon. Simple, and with the ability to shoot a potato and bludgen someone. I love it.
How much does it weigh?

What's the chances of making a spring-loaded mechanism like this one?

Also, I have to comment about your backstop - since ball valve guns are notoriously unweildy and difficult to aim, why are you shooting with a window in the background?

I was about to say the same thing as Jack, (blasted!), you should rig up a spring loaded mechanism to open that valve. It doesn't have to be fancy. I made a prototype with a door spring and some vice grips to hold the valve handle in place and let it go.

I'll probably try to make a spring loaded mechanism for it this week. Does anyone know what kind of opening times a spring loaded ball valve can get?

I'm just about to pressure test it and find where the leak is, and then fix it. After that, I'll try to get a video of it at 500 psi with the 12' barrel attached.

I'll probably try to make a spring loaded mechanism for it this week. Does anyone know what kind of opening times a spring loaded ball valve can get?

It's hard to say, it depends on the strength of your string, how much you intend to stretch it, how much leverage it has, ball valve friction etc.