Full auto combustion

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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octane89
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Fri Nov 30, 2007 10:29 am

Take this for example-On a PB gun, when you fire it constantly (and assuming that it uses co2), the tank gets colder as well as the gun itself. And while firing, the tank pressure is constantly dropping from the set psi it was at.
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Ragnarok
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Fri Nov 30, 2007 10:32 am

Yes, but we're here dealing with too much heat, not a loss of it.

I may have a reasonable solution, but I want to run some numbers first.
Does that thing kinda look like a big cat to you?
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Spitfire
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Sat Dec 08, 2007 7:40 am

What exacly will over heat and that needs to be cooled? Sori i dont realy understand
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Ragnarok
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Sat Dec 08, 2007 10:46 am

Combustion creates a lot of heat. Normally, combustions are slow firing, which allows the heat to dissipate.
If you're forcing a few hundred rounds a minute through the thing, it simply can't get rid of that heat, so you need to find a way to increase the cooling rates.

I think I've got it sorted now, so don't worry about the problem.
Does that thing kinda look like a big cat to you?
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Spitfire
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Sat Dec 08, 2007 11:25 am

aah thanx. Cant you just pump cool air into the chamber Via a fan mounted on the outside of the chanmber?
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Ragnarok
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Sat Dec 08, 2007 11:33 am

That won't be nearly fast enough at the fire rates I'm hoping to have. I was planning on using large volumes of decompressed air to vent, and hopefully that will carry away some heat.
Does that thing kinda look like a big cat to you?
iknowmy3tables
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Sat Dec 08, 2007 2:23 pm

Ragnarok wrote:Yes, but we're here dealing with too much heat, not a loss of it.

I may have a reasonable solution, but I want to run some numbers first.
the loss of heat is equivalent to saying cooling, do you know that propane is actually used as a refrigerant alternative, this concept is similar, the propane will be pretty cold. I only worry if the gun doesn't use enough propane to cool
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jackssmirkingrevenge
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Sun Dec 09, 2007 1:50 am

If it's all metal, why get rid of the heat at all? If the fuel/air mix is already hot then it will burn better, besides I doubt you're going to manage to heat it up to the extent that it autoignites, or gets so hot that the barrel will jam as with automatic firearms.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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