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My next project

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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Which One Should I Build?

Small and portable
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Big and destructive
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Total votes : 8
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My next project

Unread postAuthor: DYI » Fri Aug 24, 2007 4:46 pm

I've come up with two ideas for what I might build this winter and was hoping for some feedback on what the community would like to see.
Both of my designs use snowballs as the main ammunition, since they are for winter use, but other ammo could obviously be used.

Design one: a handheld, double barreled triggered burst disk cannon capable of firing a 3 ounce snowball at over 500 fps from a 2" diameter barrel. The entire setup is portable, and can fire several shots before needing another fill up. Both the air for the secondary chamber, and the air for the main chamber are stored at several hundred psi in two fire extinguisher tanks, both of which would be equipped with regulators to bring the pressure to the correct level. The barrels could be fired one at a time, or both at once.

Design two: a massive, 4" caliber triggered burst disk cannon capable of lobbing an 8 pound projectile at 300 fps, with a range of over 600 yards. Its maximum muzzle energy at 500 psi (its intended operating pressure), would be somewhere in the neighbourhood of 11 000 ft/lbs. Intended ammo would be large quantities (>10 pounds) of snow, and 4" diameter wax slugs :twisted:
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Unread postAuthor: CannonCreator » Fri Aug 24, 2007 4:54 pm

Dude Design 2 sounds awomse! I would really like to see that happen, Good Luck with whatever you wind up doing!
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Unread postAuthor: DirtyDan » Fri Aug 24, 2007 5:21 pm

yeah I agree... design 2 sounds pretty sweet, although I'm not sure snow would hold up very well at 300fps or much less 500fps... seems like with all that power it would just kinda spray all over the place as if you were just shooting water or something.... but what do I know? I don't have much snow experience growing up in Southern California... anyhow, both designs seem cool, but the idea of launching 4" wax slugs... well... that's just sick...
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Unread postAuthor: frankrede » Fri Aug 24, 2007 5:30 pm

I doubt that the snow would hold together but other than that sounds good.
In design 2 what would your chamber be made of?
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Unread postAuthor: noname » Fri Aug 24, 2007 5:43 pm

Making snow hold together is really pretty easy. You just make a large snowball, shave it down until it fits in the barrel, and then dip it in water for a few seconds. It gets all frozen together, so it's more of an iceball than a snowball.
DYI, are you going to use a 4" union? That's good (insane) in performance, but making burst discs will be a total PITA, especially if you intend on having them hold 500 psi. Multiple layers of sheet metal is your best bet.
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Unread postAuthor: frankrede » Fri Aug 24, 2007 5:59 pm

For a burst disk that size....
I would try sheet pvc?
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Unread postAuthor: Redcoat » Fri Aug 24, 2007 6:01 pm

design two by far.In a snowball fight you could lay down suppressive bombardment without them even seeing you, maybe even before they leave their house :wink: ). Design two. :D
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Unread postAuthor: DYI » Fri Aug 24, 2007 6:34 pm

Well so far, it looks pretty well unanimous.
To answer some questions:
The union would be 2" max, otherwise I couldn't make strong enough disks. Also, I can not order online, so any union larger than 2" is not even possible.

I'm pretty sure that I can get the snow to hold as long as it is sticky enough, and there would be a sabot behind it.

The chamber will be made of SCH 40 galvanised steel pipe and fittings, and I imagine that a 500 psi shot will be a rarity, due to the difficulty, noise, and sheer volume of nitrogen it will use.

The wax slugs will happen, but probably not many of them, due the fact that the cost per slug would be about $30, and they would be destroyed on impact with a target, or the ground. When I do decide to dump 30 + dollars on a single use projectile, I'll be sure to post a video of it shooting through a building or something...

And now a question of my own: Can anyone think of a readily available material with which I could make a burst disk that would hold ~300 psi in a 2" union? This will use the pressure differential design (and with pressure suddenly jumping to 200 psi past the burst pressure, I can't see the disk holding very long), so I will need two of whatever disk I decide to use.

At its projected normal operating pressure of 160 psi or so, this should be able to chuck a 4 pound projectile slightly over 300 yards, with a respectable 2800 ft/lbs of muzzle energy. I should be able to get reload time down to about 5 minutes, but with artillery like this, one shot is all you need (note that this will NEVER be used against human targets).

I got the idea for this from a movie I saw, where hundreds of kids were having a big snowball fight, and somebody had built a slingshot that hurled 2' diameter snowballs.

Judging by the response so far, I'll build the big gun. Here's the progress so far: Nitrogen reg will arrive in 4 days. May buy 4" barrel tomorrow. Credit app. to lease 92 cubic foot nitrogen tank has been sent. I will hopefully post the finished project, complete with stand, in November or December, depending on work and school.

@Frankrede: saw your new title. I assume you play Halo.
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Unread postAuthor: noob of noobs » Fri Aug 24, 2007 7:31 pm

Design 2 does sound good and all, but the first one appeals to me more. Artillery is nice, but it seems unpractical to be carying that thing around all the time. Smaller guns however, are easier to carry around, reload, and are more versatile overall.
Still though, the thought of hitting something 600 miles away sounds wicked! If you do build it, make sure to get a cart or something to toat it on. Do post some designs. I have no idea as to how you'd pierce a disk holding 300 psi, but it must be possible. What would your barrel be made of? I'm also very interested in your sabot.

EDIT: Oops.. I meant to say 600 yards. Thanks DYI!
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Last edited by noob of noobs on Sat Aug 25, 2007 9:31 am, edited 1 time in total.
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Unread postAuthor: DYI » Fri Aug 24, 2007 7:38 pm

Well, I wouldn't exactly be "toting it around", and they'll both have hideous reload times anyway. And I won't be trying to pierce the disk, it uses the pressure differential design. I will build a well balanced stand for the monster gun, probably with wheels (the barrel will be 12' long)

As much as I would like to shoot 600 miles, the estimated range with an 8 pound projectile is 600 yards.

I will post a rough (by my standards) schematic of each design sometime tomorrow.
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