Oxy-Acetylene.

Post questions and info about combustion (flammable vapor) powered launchers here. This includes discussion about fuels, ratios, ignition systems and anything else relevant to launchers powered by igniting things like hairspray or propane.

Postby SkweezMyCheez » Sun Oct 22, 2006 12:15 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by blackspire
[br]"It really won't matter what you use for fuel the gun'll perform like crap. Your chamber to barrel ratio is about 2:1 ... the barrel should be twice as long for this size chamber." That's just the dimensions I used for my first ABS potato gun, and it works awesome...?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">


...nope, it doesnt work awesome... you just think it does. make a longer barrel
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Postby sgort87 » Sun Oct 22, 2006 1:51 pm

Try a 10 foot barrel and see the difference, seriously.
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Postby blackspire » Sun Oct 22, 2006 2:38 pm

10 foot barrel? Does anyone know what the correct barrel length should be using the 1.5:1 C:B ratio? I am REALLY bad at math, and am not sure how to do that.
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Postby An Apple Pie » Sun Oct 22, 2006 3:34 pm

Not to be mean but this probably isn't the best hobby for people that aren't good at math.
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Postby sgort87 » Sun Oct 22, 2006 4:33 pm

Oh be nice pie man.

The reason you are having problems is because you didn't know until now that the ratio you want for propane is .6:1 to .8:1.

I gave you the length for .8:1 up there. Go 13' 4" for a .6:1 ratio. That would be quier and a little more powerful but that long is difficult unless you can get 20' lengths and transport it.
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Postby blackspire » Sun Oct 22, 2006 4:37 pm

So your saying, a 13 inch long by 4 inch chamber, with a 10 foot barrel? It would be hard to transport a big metal cannon like that.
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Postby SpudStuff » Sun Oct 22, 2006 6:55 pm

You think? Steel is quite heavy. But the longer barrels are amazing. The power increace is very noticible.
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Postby SpudBlaster15 » Sun Oct 22, 2006 7:01 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by blackspire
[br]I am REALLY bad at math, and am not sure how to do that.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Use the formula Volume = pi x radius squared x height to calculate both your barrel and chamber volumes, then divide the chamber volume by the barrel volume to obtain your ratio.
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Postby Navigator7 » Sun Oct 22, 2006 8:27 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by blackspire
It would be hard to transport a big metal cannon like that.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Sgort would be happy to move your cannon for you!
;'-)
Email me for his 1-800 number.......
;-)
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Postby sgort87 » Sun Oct 22, 2006 9:38 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by blackspire
[br]So your saying, a 13 inch long by 4 inch chamber, with a 10 foot barrel? It would be hard to transport a big metal cannon like that.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
No, I was giving you an alternate barrel length. Theoptimum barrel length is somewhere between 10 feet and 13 feet 2 inches. Those barrels are for your 2 foot chamber.

I actually suggest making your chamber one foot long and use a 5 foot barrel. They are much nicer to hold and operate.
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