Describe the ultimate potato cannon

[Moonbogg]

Describe what you feel would be the ultimate potato cannon. Bore size, pneumatic or combustion, power class, features such as spud cutting and breach loading, ease of use should be very important as well, etc etc. Consider all you have seen and learned from this hobby over the years and use your mind to describe the perfect implementation of all lessons and techniques accumulated for the best spud gun ever.

[jackssmirkingrevenge]

Well it has to be cartridge fed select fire, obviously

[Spudinator]

Well I suppose that's kind of an open-ended question, but here goes. I'll break it down to a few categories

Ease of use/less performance: propane injected combustion with muzzle or breach barrel knife.

Consistent performance/compressor hassle: regulated pressure pneumatic diaphragm valve with QEV exhaust.

Best power/PITA to reload/everything: Burst disc Hybrid (obviously).

Most fun/best type: All three.


There's no such thing as the best type of potato gun. There is however, the best type of potato gun for the job. That's the question you should be asking. Also remember that different people have a different idea of what's "best". So in essence, the best gun is what you like most for what you are doing, not what other people like.

I personally really enjoy combustion guns fueled with a burnzomatic torch head, if I want to go out and have some fun with the boys, that's what I take. I've got an over/under with a 3.5'x4" chamber and 5'x3" barrel that just doesn't disappoint, ever, and a coax over/under golf ball gun with 3'x3" chamber and 5' sdr21 barrel (she's a bolt action too) that shoots around 700 fps. Those are definitely my favorite guns, but they certainly aren't the best. Like I said, the best is what you like the most for what you are doing.

Have a good one fellas.

[jrrdw]

A spud cannon that pays it's own way!

Once that happens I prefer a pneumatic barrel sealing piston valve 2" or smaller with built in air compressor. As for the rest of the build 2:1 rule of thumb works well. Add on's would be but not limited to built in magazine for easy loading and less of it. Interchangeable barrels would be nice. Light weight with break down capability for easy trans porting. Upgradability is a must because it's my cannon and I can do what ever I want with it at any time of my choosing.

[D_Hall]

Bore: 24 inch.

Barrel length: 60 feet.

Break action.

Barrel on a carriage system such that the breach can be opened/closed without raising/lowering the CG of the barrel. This means easy movement despite the size.

Valved would, of course, be nice, but I've had good luck with burst disks.

Propellant: Propane and air at 10X mixture with an option for methane/air/helium.

Goal: 1000 lbs to transonic.

[Moonbogg]

Bore: 24 inch.

Barrel length: 60 feet.

Break action.

Barrel on a carriage system such that the breach can be opened/closed without raising/lowering the CG of the barrel. This means easy movement despite the size.

Valved would, of course, be nice, but I've had good luck with burst disks.

Propellant: Propane and air at 10X mixture with an option for methane/air/helium.

Goal: 1000 lbs to transonic.

Are you using any existing materials which would act as constants in the design to be worked around? I'd expect some forgings to be needed for valving components and maybe even the chamber, perhaps 4340 forgings would be well suited for it's strength and high toughness. If it were me, I'd settle for nothing less than one of the toughest, strongest steels if it's going to get slammed by a giant piston. They can forge large 4130/4340 tube for machining the chamber and valving, which can be ordered heat treated to the desired hardness and forged with enough machining stock for cleanup, but the barrel would be very long, so maybe an assembly of multiple forgings would be needed unless you find a vendor who can either forge stock that large or bore solid stock that long. 24" ID isn't that large, but the length would need to be dealt with. Any thoughts thus far on particulars? It would be expensive. Maybe about $500,000 to 1 million?

[D_Hall]

I confess that I've not really thought about the details of the valving since I doubt I'd get the funding to build such, burst disks work well, and burst disks are a negligible cost in the Big Picture. The point being that whimsy aside, the gun would almost certainly use burst disks.

With the valve out of the equation, everything would be easy to build with off the shelf parts and machinery. Start with heavy seamless DOM pipe and go from there. Vera taught me a lot on that front. The only trick is (as you noted) the barrel length. I think it's doable to manufacture a couple of custom flanges that would align two barrel pieces (40' + 20') but I confess that I've not gone too far down that road. Multiple part barrels are definitely a thing, the question is whether or not you could start with mere pipe to build one. Worst case scenario is that the barrel is 45' long. That's still pretty decent.

As for cost.... Yeah, somewhere in the $750k range.

[Alex345]

A fully automatic 40 x 400mm cannon based on the 40mm Bofors with pre-charged x10 hybrid shells. Tho that would never generate enough gasses to cycle any kind of gas operated action, and you would most likely want that thing to have a locking bolt. Thus either an entire pneumatic standalone piston/cylinder that's connected to an electric pressure sensor somewhere halfway along the barrel, that activates a QEV to blow back the massive bolt OR en electric motor using a crank, chain or gears.

[Moonbogg]

I confess that I've not really thought about the details of the valving since I doubt I'd get the funding to build such, burst disks work well, and burst disks are a negligible cost in the Big Picture. The point being that whimsy aside, the gun would almost certainly use burst disks.

With the valve out of the equation, everything would be easy to build with off the shelf parts and machinery. Start with heavy seamless DOM pipe and go from there. Vera taught me a lot on that front. The only trick is (as you noted) the barrel length. I think it's doable to manufacture a couple of custom flanges that would align to barrel pieces (40' + 20') but I confess that I've not gone too far down that road. Multiple part barrels are definitely a thing, the question is whether or not you could start with mere pipe to build one. Worst case scenario is that the barrel is 45' long. That's still pretty decent.

As for cost.... Yeah, somewhere in the $750k range.

I swear to all things holy and not, if I had the money lying around, I'd build it. I would actually be crazy enough to go through with building this thing. It would be absolutely hilarious.

A spud cannon that pays it's own way!

Once that happens I prefer a pneumatic barrel sealing piston valve 2" or smaller with built in air compressor. As for the rest of the build 2:1 rule of thumb works well. Add on's would be but not limited to built in magazine for easy loading and less of it. Interchangeable barrels would be nice. Light weight with break down capability for easy trans porting. Upgradability is a must because it's my cannon and I can do what ever I want with it at any time of my choosing.

I like this idea. I've yet to build a proper pneumatic. I actually like this idea a lot. It's simple yet has the benefit of the pump. When you say 2:1 you mean chamber to barrel ratio, correct? I would likely target a 200psi pressure for a pneumatic. I feel that should offer a reasonable and substantial power increase over the already impressive 120-160ish pressure ranges that seem common in pneumatics. The biggest challenge would be finding a suitable pump. It would likely have to be an over-under design I think for barrel exchanges. A coaxial could be done and still exchange barrels though, but the length would be a bit much I'm afraid. I think I might get to work on this. I need a pneumatic for my collection.
I could start designing now and when I am able I'll build it. I imagine a large capacity of lithium RC hobby batteries for the pump. Maybe I can even design my own pump and use a high torque RC motor with an impeller pump or something. I don't know much of anything about pumps, but a little research can direct me to the best option. Any ideas about a pump that could hit around 200psi without being completely ridiculous in terms of size and noise?

[D_Hall]

I swear to all things holy and not, if I had the money lying around, I'd build it. I would actually be crazy enough to go through with building this thing. It would be absolutely hilarious.

Let's just say that I didn't come up with the performance specs on a whim. I was asked by some folks if it was doable. I told them it was. Mind you, at this point it's all just idle chatter around the water cooler, but maybe some day....

[jrrdw]

I like this idea. I've yet to build a proper pneumatic. I actually like this idea a lot. It's simple yet has the benefit of the pump. When you say 2:1 you mean chamber to barrel ratio, correct? I would likely target a 200psi pressure for a pneumatic. I feel that should offer a reasonable and substantial power increase over the already impressive 120-160ish pressure ranges that seem common in pneumatics. The biggest challenge would be finding a suitable pump. It would likely have to be an over-under design I think for barrel exchanges. A coaxial could be done and still exchange barrels though, but the length would be a bit much I'm afraid. I think I might get to work on this. I need a pneumatic for my collection.
I could start designing now and when I am able I'll build it. I imagine a large capacity of lithium RC hobby batteries for the pump. Maybe I can even design my own pump and use a high torque RC motor with an impeller pump or something. I don't know much of anything about pumps, but a little research can direct me to the best option. Any ideas about a pump that could hit around 200psi without being completely ridiculous in terms of size and noise?

Yes, 2:1 chamber to barrel ratio is correct. As for the pump it really depends on the chamber size. Big chamber needs a high volume pump, with a smaller chamber you could get away with a simple shock pump. If it's the larger pump, 2 stage is better for 160psi and higher pressures. Home built pump.