Plastic Propane Injection System...Safe?

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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revans
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Tue Feb 19, 2008 3:24 am

Thanks for all the info, you seem to be a bit of a spudgun guru.
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MrCrowley
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Tue Feb 19, 2008 3:28 am

Thanks, I do what I can to help.

Can't own a gun since i'm stil in highschool, so may as well make one :)
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DYI
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Tue Feb 19, 2008 8:27 pm

It isn't that piston or burst disk guns are really loud, it's just that when people use inefficient ratios on them, they're louder than ball valve or sprinkler valve guns with similarly inefficient ratios.

My 3" bore, 170 cubic inch, 500 psi burst disk gun is quieter than my simple deoderant powered combustion, simply due to achieving higher efficiency.

And MrCrowley, I went pneumatics, and I'm going back. Not completely, but the unfortunate reality that I'll now be paying $5.40 or so for the gas alone for a single shot made me decide to pursue more cost effective (if more complex) methods of obtaining the pressure I need.

Of course, if you live in a suburban or urban area, you can't really build something so big that gas consumption alone becomes a problem, so pneumatics are probably better, as well as being easier to build and maintain than combustions.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
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Ragnarok
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Tue Feb 19, 2008 9:23 pm

MrCrowley wrote:Once you go pneumatic, you don't go back.
DYI may not agree, but as I'm sure you guys know, I'm a big fan of pneumatics. I've scarcely touched combustion in ages.

I might build an advanced combustion at some point because I can - but when EVBEC predicts an advanced combustion with a 5' long 40mm bore barrel (longer than HEAL's entire length) will only have the same muzzle energy as my (in)famous cannon currently does - let alone when I raise the pressure - it doesn't exactly make the concept more appealing.

Still, I have this interesting idea for firing water balloons from the combustion, then shooting them down with a buckshot of airsoft or metal BBs in a form of clay pigeon shooting.

Combustions don't give enough velocity or energy, and hybrids don't appeal to me - that's partly because I can't draw too much attention to myself in a suburban area, and hybrids have the threat of creating sonic booms. Muzzle reports can be suppressed, but breaking the sound barrier might be a little harder to cover up.

There are also energy limits. Still, the concept for my 1000+ ft-lb quad piston valved 500 psi Leviathan still sits around - designed for putting potato across the garden at 0.8 Mach - or maybe for putting 1750 ft-lbs into the heavy 55g CO2 cartridge I have around, and is shown here dwarfing an inert .50 BMG round: Clicky
Does that thing kinda look like a big cat to you?
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MrCrowley
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Wed Feb 20, 2008 1:53 am

I meant you start revolving around pneumatics, like I said i'm going back for a Hybrid and Advanced Combustion, but my life still revolves around pneumatics.
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