one-ended combustion 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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EpicMadness
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Sat Nov 26, 2011 4:36 pm

i came up a design on a whim where a jamjar jet effect is being utilized:

Image

the theory i made up is that the metal rubbish would help create turbulence for the fuel to mix, and help create a stopper-like effect for increase in pressure in the main combustion chamber.

my concern is if this cannon could pull back fresh air from the exit vent after the ignition where, i've heard from people, creates a temporary vacuum(Credits for the jamjar jet theory).

PS: my fuel would be butane, i got tons of lighters here and there, if not, gasoline(would be insanely dangerous).
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motorfixer1
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Sat Nov 26, 2011 6:10 pm

That might work with a short barrel. Obviously a short barrel will limit your velocity, but the design might work. You could build a small model out of pvc to test for realitively cheap if that is not a concern. Neat idea none the less.
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EpicMadness
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Sun Nov 27, 2011 3:41 am

It is a short barrel, it would be used as a mortar and having it compact would be a cons for easier storage. well thanks for the heads up.
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jackssmirkingrevenge
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Sun Nov 27, 2011 3:46 am

I don't see the benefit vis-a-vis a conventional cannon.
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Brian the brain
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Sun Nov 27, 2011 4:25 am

That stopper effect would also be achieved by inserting something into the barrel....like....a projectile... :roll:


Not sure if this metal crap thing will do anything but choke flow.
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EpicMadness
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Sun Nov 27, 2011 5:31 am

no no, the metal crap is used to pre-pressurize the main chamber because of the fan, well not 2x or higher but at least provide a slight higher pressure.
if it doesn't work well i could just remove the metal crap :lol:

actually i designed it as a semi-auto noise maker where putting in balls of paper, spud, etc. is still viable.
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pneumaticcannons
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Sun Nov 27, 2011 5:39 am

Umm, that fan isn't going to create pressure at all... well at least not enough for anything to notice.
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EpicMadness
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Sun Nov 27, 2011 7:30 am

can't argue with that... well theories are theories, applying this http://www.spudfiles.com/forums/theoret ... 23526.html to the build was the idea and then the idea of turbulence for mixing came up as well.

btw, anyone tried using joule thief circuit for driving ignition coils or transformers?
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