2 chambers 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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CannonCreator
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Mon Aug 13, 2007 1:48 am

Would it be safe to have a combustion potato cannon with 2 chambers? made of ABS or PVC schedule 40?

So basically would it be safe to have a cannon with 2 seperate chambers and have 2 differtenet ignitions, and are filled with the same gas seperatly, that go off at the same time, that both meet at the barrel like below?

1st chamber (below)
___________
[___________] ______________
___________ > [_____________] < barrel
[___________]

^
second chamber



__________________________________________________

They will each be filled with the same gas, but sepreatly.

And they will both be ignited by a stun gun, but 2 seperate guns, that will be set off at the same time.

each chamber would be 15" long, and 4" in diameter, and the barrel would be 2" diameter

WOULD THIS BE SAFE?
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thanks in advance!
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thespeedycicada
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Mon Aug 13, 2007 1:57 am

I think it would be fine with sch 40 and a long barrel but i would use the burntlatke rat calc to find out the c:b ratio
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kablooie
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Mon Aug 13, 2007 1:57 am

I would think that it would be fine to have two chambers combust simultaneously. Why not have just one larger chamber? ( Is space an issue?) This would eliminate the possibility of having one ingnition go off even slightly before the other one. wouldn't it take away from the power of the gun if one of the chambers went off before the other?
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MrCrowley
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Mon Aug 13, 2007 2:01 am

Yes, its fine. Loads of people have done it before just search it.
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CannonCreator
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Mon Aug 13, 2007 2:07 am

k, thanks guys I will use the ratclac, wereever i get that, I will just search it. And Im going to use 2 stun guns, and make a 2 control boxs, and link the trigger to 1 of the control boxs, I think 2 chambers will giv emore of a shouve. Well I don't know for sure but im going to try, thanks guys!
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thespeedycicada
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Mon Aug 13, 2007 2:09 am

I dont think you would do this for space it would be much bigger albiet 15 inches taller.Are you doing this for a cool looking cannon? because that would be cool.
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CannonCreator
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Mon Aug 13, 2007 2:20 am

What do u want the ratio to turn out like. Should the chamber ratio be higher then the barrel ratio? or should they be even?
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TwitchTheAussie
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Mon Aug 13, 2007 2:24 am

The c:b ratio just helps to get optimum performance in acceleration. You can use 1 stun gun also. Link the two chambers in a series circuit. Just google burntlatke for the ratcalc. Also burntlatkes a good site. Need any more help just keep posting :P
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thespeedycicada
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Mon Aug 13, 2007 2:26 am

the c:b ratio or chamber barrel ratio is the ratio beetween the chamber and barrel i think 1.5:1 is optimal
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CannonCreator
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Mon Aug 13, 2007 2:36 am

ok thanks i just got rat calc. So i do want my chamber to be a larger raito then my barrel ratio?

So I want the ratios to be pretty close?

or waht, thats the only part im confused on.

what if the chaber ratio is bigger then the barrel? will power from the chamber be wasted, or will it break the barrel?

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THANKS FOR HELPING GUYS, THIS IS THE ONLY PART I NEED HELP ON NOW!
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thespeedycicada
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Mon Aug 13, 2007 2:38 am

u want 1.5:1 or close
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frankrede
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Mon Aug 13, 2007 3:41 am

thespeedycicada wrote:u want 1.5:1 or close
or .8:1 for optimum performance.
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thespeedycicada
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Mon Aug 13, 2007 3:51 am

frankrede wrote:
thespeedycicada wrote:u want 1.5:1 or close
or .8:1 for optimum performance.
really? but im pretty sure it was 1.5:1 on burntlatke and wouldnt having a smaller chamber than barrel result in less power?
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dongfang
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Mon Aug 13, 2007 8:42 am

Hi,

The C:B ratio discussion is about the oldest one in the spudding world.....

.8:1 is optimal where you want a muzzle velocity and a small chamber size. It will give you a gun where there is no acceleration near the muzzle.

Some people consider that to be a waste of barrel -- the last 1/3 of it or so contributes very little to velocity but just makes the gun large and cumbersome. They go for a larger chamber or cut off their barrel, till they end up around 1.5:1 or something like that. Now there is good acceleration through all of the barrel, but some chamber energy is wasted (and the gun becomes louder).
Using propane, fuel will cost you like $0.02 a shot, so this needs not be considered.

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Hailfire753
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Mon Aug 13, 2007 8:53 am

No need for two stun guns!! One is more than enough to wire to spark gaps, one in ewach chamber. This way, they will go off at the same time.

Simpler = better
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