co axial

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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Cosmic Muffin
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Wed Dec 17, 2008 12:47 am

what do you blokes rekon about having a coaxial combustion cannon ?
just i have never seen one before.
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jook13
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Wed Dec 17, 2008 1:00 am

I think it could be a good thing if you were really concerned about keeping it compact.
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Gippeto
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Wed Dec 17, 2008 1:03 am

Co axial is just the configuration. Around here, it means that the barrel runs well into the chamber.

If I remember correctly, the reason that you don't see many co axial combustion canons is efficiency losses.

The barrel being in the combustion chamber, robs heat from the reaction, lowering the max temp and thus the max pressure achieved.
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Cosmic Muffin
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Wed Dec 17, 2008 1:39 am

yer well i spose your guys are right, too many energy exchanges or whatever it is, i might try it one day though. whats the harm in trying these things :wink:
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Xxplosive42o
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Wed Dec 17, 2008 2:13 am

No harm at all Cosmic. Innovation is a great thing because building the same thing can get quite boring. :?

Let us all know if you decide to take the endeavor. :P

Cheers!
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Lentamentalisk
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Wed Dec 17, 2008 3:02 am

just make sure to have a lot of spark gaps, all along the length of the chamber, or at least one 1/4 of the way from each end. That will effectively double the flame front area.
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CasinoVanart
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Wed Jan 07, 2009 6:09 pm

This idea makes loading easier as you can load through the back of the chamber. I have used the idea successfully on a few of my combustions, go for it!!
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sputnick
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Wed Jan 07, 2009 7:01 pm

I think that there would not be much point, seeing as the point of pneumatic coaxial guns is to allow for a piston, and more airflow. With combustions, however, that is not an issue.
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CasinoVanart
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Wed Jan 07, 2009 7:09 pm

Ya i know but i like doing things different :D Just makes for easier loading. The only thing i don't like is that it robs capacity from the chamber, i just make the chamber a bit bigger to start with.
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Combustion Monkey
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Sun Jan 11, 2009 3:49 pm

Hi folks this my first post here. I have built a coax gun with a 346ci chamber, thats counting the space the barrel takes up. The barrel also passes all the way through the chamber for breach loading. It also has a pc fan for venting and mixing. The thing runs great and can handel a 13ft barrel although it usually only runs about 4ft of external barrel, i'll get pics up as soon as i can.
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Combustion Monkey
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Sun Jan 11, 2009 4:19 pm

This is the gun, I hope the pic works, not very handy at forum posting yet. The wine bottle is there for scale. [img][img]http://img89.imageshack.us/img89/9646/picture066jl6.th.jpg[/img][/img]
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starman
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Sun Jan 11, 2009 4:51 pm

Hey Combustion Monkey, that looks like some nice weaponry you have there. Why don't you post it in the combustion cannon showcase along with more details and somewhat bigger pics.

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