New member - First propane gun

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.
MortarArmy
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Mon Sep 17, 2007 12:05 am

Started off as just the standard aerosol spay and pray gun, but that was getting old and messy. SO....less than 24hrs after its initial creation, thought id give a shot at metered propane. I know my ratios are off, im missing a few components, and its kinda ugly...but it works darn well.

12x3" Chamber
24x1.5" Barrel
11x.5" meter with the T
bbq ignition
propane/mapp gas fuel.


Im filling the meter to about 18psi, which according to the calc is a little rich, but seems to fire a little stronger than right dead at 4.2%. Probably factor of i havent accurately measured the chamber, and the chamber isnt 100% air tight yet. I need to replace the screw on end cap with a ball valve or something.

Anyway, this is my second gun. First one was a few years ago that did well, but was very basic. Didnt even have the handle/trigger, used lysol for most shots. This one isnt as big, but shoots just as far.


Image

Image

Image


few mods to come... Thinking about a chamber fan, possibly cleaning up the wiring/tape job to make it look a little better, and definatly getting rid of the screw on end cap. those a such a pain to remove after every shot
Novacastrian
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Mon Sep 17, 2007 12:42 am

Looks pretty cool to me, i love "Ghetto" style guns.
A chamber fan and a paint job could do wonders, and a sealed chamber :P A fan increases power by about 30% i believe.

Welcome to Spudfiles :D
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Insomniac
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Mon Sep 17, 2007 1:41 am

Nice gun there, but is that reducer dwv? Other that its a great little cannon.
Welcome to spudfiles :D :D

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Redcoat
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Mon Sep 17, 2007 3:16 am

It doesn't look to ghetto, though a paintjob would do it justice.

An awesome, gun. Damage pics would be awesome.

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Happy SPuddin'
Poo.
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mark.f
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Mon Sep 17, 2007 5:38 am

Nice first gun. I really don't think it matters how it looks as long as it works. You'll get better at "streamlining" everything as you build more cannons.

And insomniac, SCH-40 solid-wall DWV fittings are generally accepted to be O.K. to use with combustion cannons. PR fittings, (ASTM D2466/2464/2467), are for pneumatics or hybrids. But it wouldn't be a bad idea to use them on a combustion for a little extra safety.

Once again, good job, and freaking stick around. :x
MortarArmy
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Mon Sep 17, 2007 4:34 pm

I dunno what a DWV fitting is...i just grabbed the first one i saw.

i actually kinda like the way it looks, and i have no intention of painting it. If it doesnt make it work better, its staying the same. right now its got a bit of a mad-scientist crazy contraption look to it. gotta love bits of hose, gauges and valves all over the place.
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thespeedycicada
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Mon Sep 17, 2007 5:07 pm

welcome 2 the forums dude! kool cannon nice and ghetto :D.Dwv fittings or dryer waste vent fittings are non pressure rated fittings that while they might be ok for combustions are unsuitable and VERY dangerous hope this helps!
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TwitchTheAussie
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Mon Sep 17, 2007 5:59 pm

Believe me its nice to see a guy who likes unpainted cannons :lol: . You did some good work on that and adding a fan does increase the power. Believe me :wink: . Also the ball valve idea is a good idea :lol: .

Have fun and welcome to the forums :D x the area of Australia squared by the counterweight of the Earths axis of motion :lol:
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iknowmy3tables
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Mon Sep 17, 2007 6:22 pm

fixed regulator i like your style man 8)
now get your self a chamber fan and your ready to p0wn
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veginator
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Mon Sep 17, 2007 7:44 pm

looks pretty good but you want to try not to get dwv fittings.or it could blow up in your hands. Welcome to the forums :toothy10: :toothy10: :toothy10:
MortarArmy
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Mon Sep 17, 2007 8:13 pm

meh, they were the only fittings i saw, and they were next to the rest of the pressure rated pvc there, so i dunno. gotten maybe 50 shots now, so i think ive got a good idea of the power.

Doesnt seem to be performing to my expectations though, im probably only getting 125 yards off a perfect fuel dump and well seated potato. I dunno if its just because the gun's small and this is normal, or if ive got something way off. i know my barrel is about 6" off prime, but i cant imagine it making that big a difference.
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thespeedycicada
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Mon Sep 17, 2007 8:39 pm

barrel length makes a very big difference make it a foot or two longer and you will see a big performance increase.
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mark.f
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Tue Sep 18, 2007 6:04 am

Make that barrel around 60", (3 feet longer that your current one), and you may see a good performance increase, depending...
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Hubb
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Tue Sep 18, 2007 6:13 am

I'm agreeing with everyone else, nice cannon (and Welcome to Spufiles :D, just times one but it'll do ). Take their advice and add the fan and barrel length.

Also, does cutting the barrel like that actually do anything for the performance? I've seen it done before but never tried it to see if there was any improvements.
iknowmy3tables
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Tue Sep 18, 2007 8:41 am

yeah the barrel is pretty short but while your extending it you can make it an over under design, don't forget the chamber fan
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