RMS's Cannon

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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PCGUY
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Sun Feb 13, 2005 12:12 am

<div align="center">RMS CANNON

Provided By - RMS

I tested it out this weekend. Barrel is 10' x 2" and it is still only a 1.2:1 C:B ratio. Another 5' extension and I'd get to .8:1. Quietest gun yet, though. And lobbs whole potatoes farther than anything I've built yet. Incorporates several features I've described here in various threads:

1) Detachable cheap and easy propane meter. Female air fitting mounted in the end cap.

2) Simple removable fan mount, (fan sits in bottom of threads with ground corners so the fan front end fits in but the fan back end won't, so it won't fall in, and is trapped securely when back end assembly is screwed in. Battery is held inside the rear chamber. Fan removes quickly and easily for maintenance)

3) My own trigger handle design...feels comfortable to fire.

4) Splice fitting in the middle of long chamber (under trigger assy) for extra chamber strength.

5) Back-up flint sparker for those times when the spark fails.

6) Screw-in Barrel with screw-on extension, very similar to a design posted here. Worked great and it all fits nicely in the car.

Provided By - RMS </div>
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Last edited by PCGUY on Sun Jul 23, 2006 1:05 pm, edited 1 time in total.
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theexp
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Sun Feb 13, 2005 7:35 pm

Nice, Its quite a large cannon, i love the Detachable propane injection system. :D
I like the handle real cool.

IT must do some dmg :evil:
boogieman
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Tue Mar 08, 2005 3:55 pm

dang thats awesome i like the handle looks like a bazooka kinda.... kinda long and hard to get around but nice!!!!! bet it can do some major dmg!!!! :twisted: :evil:
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fred_roux
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Tue Mar 15, 2005 9:43 pm

ohhhh..another personn that trust ABS :P ...like me...if u wanna see mine go on that site fredleroux.skyblog.com

nice canon dude :wink:
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No.Va
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Thu May 12, 2005 8:08 pm

hmm, this bugs me, i see some people using ABS and some using PVC, im just starting out and I'm wodering which one is better or safer to use. can anyone give me some tips please? it would be greatly apreciated.
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CS
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Thu May 12, 2005 10:21 pm

Every one ive heard has said that PVC is safer and better but i like ABS better because its always straight and PVC is warped if it is left in the sun which makes me think its weaker. I recommend ABS looks cooler to.
spudshot
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Fri May 13, 2005 3:19 am

use ABS only with a combustion cannon, with pneumatics use pressure rated (NSF-PW) fittings (not DWV) and use pipe that has a pressure rating, avoid cellular core pipe
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No.Va
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Sat May 14, 2005 11:05 am

hmm, thanks, that helped alot, but what is cellular core?
and is there any chance if i used ABS that it would explode while im using it or is the cumbustion not have enough pressure to do that?
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Sat May 14, 2005 2:42 pm

well most people have never had a combustion blow on them, when they do its just been the cleanout cap, try to get a brass cap or use a male adapter and a glue on cap.

Cellular core means that the walls of the pipe arent solid, which makes it VERY weak, ABS is cellular core, and thats alright for a combustion, but PVC in combustions or pneumatics NEEDS to be sch 40 AND have a pressure rating (XXX psi)
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toza
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Sun Oct 16, 2005 7:22 am

hmmm i'm just like no.va i'm starting out i've got a 6" by 5 " chamber and a 2" by 4 foot barrel i'm having a heap of trouble with igniting it as ppl around here dont sell bbq lighters or lantern lighters any ideas?
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Cronic
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Thu Oct 27, 2005 3:23 am

I have an idea but I don't know is it safe or is it doable as I've never tried it before. You might wanna take a 9V battery and try the spark with that or maybe a cigarett lighter with 2 really wide nails or bolts to skin off as much resistance as you can. And another idea is a hair dryer wire. It's made from materials(I don't know how they are called in english) that give much heat don't know it you can maybe take one out and if it'll work on a battery or is the battery too weak for it? Anyway you can always get one of those stove lighters they'r pretty good and I think you can get them anywhere.
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toza
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Thu Oct 27, 2005 3:27 am

ty but i found a sparker so it all good :) :) :) :D neighbors got really annoyed cause i was fireing it for a few days they called the cops though they went balistic :evil: :twisted:
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Cronic
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Thu Oct 27, 2005 3:31 am

Dang I hate those busybody neighboors. I woud like to spud the hell out of they'r house.
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toza
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Thu Oct 27, 2005 3:56 am

i agree theyre so annoying i think the eggs in my fridge need a workout 8) :twisted:
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boilingleadbath
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Thu Oct 27, 2005 2:40 pm

The wires in the hairdryer (nicrome [nickle-crome alloy] for future reference) may work as an ignition scource. Orange-hot is good enough to ignight our gasses (I think the ignition temp is about 400-600*C)

...and I hope you are planning on throwing those eggs. We don't need you to be giving us a bad name. Just kidding; don't egg stuf.
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