My mini with tripod and ridiculous C:B ratio

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.
Tshylea
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Sat Dec 02, 2006 11:02 pm

I have at least half a dozen mini's, but this one is probably the coolest. I used the tripod from a digital camera, a BBQ sparker, a pen, and a really big pill bottle. It uses hair spray and fires a Q-tip about 30 feet, but its snowing outside, so I just shot my door. The recoil knocks it over about half the time. My camera's mic won't pick up really sharp, loud noises, but this mini is about as loud, and kicks as much, as a .22 rifle.

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Last edited by Tshylea on Sat Dec 02, 2006 11:18 pm, edited 1 time in total.
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Sat Dec 02, 2006 11:06 pm

loud as a .22 and kicks as much??? doubt that...


Cool gun though. Bet the tripod cost more than 20 of the guns though:)
Tshylea
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Sat Dec 02, 2006 11:09 pm

Well assuming that a .22 rifle weighs a couple pounds and this is only a few ounces....
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frankrede
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Sun Dec 03, 2006 1:35 am

haha, nice mini,lovving teh tripod
Current project: Afghanistan deployment
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SpudStuff
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Sun Dec 03, 2006 10:28 pm

Um... No. Could kick as much but no where near the .22 on the dB scale.
Nice though!
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falcone
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Wed Dec 13, 2006 8:11 pm

nice gun, 1st mini ive ever seen like that

n00b question:
what is c:b ratio stand for? is it chamber:barrel ratio? if so whats the ideal ratio?
Tshylea
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Wed Dec 13, 2006 8:35 pm

Ya it stands for chamber:barrel ratio. Ideal is around 0.8:1
I didn't measure it or anything, but I'm guessing that mini would be around 7:1. I could be wrong though, that's just my bad guess.
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falcone
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Thu Dec 14, 2006 7:58 am

ok thanks, it would still be same for pneumatics right?
Tshylea
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Thu Dec 14, 2006 3:57 pm

Uhhhh probably. I'm not positive, but if it isn't exactly the same, it would be pretty close.
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Bluetooth
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Thu Dec 14, 2006 4:48 pm

No completely different idea for pneumatics because pneumatics have a constant supply of air comming out of the barrel untill the ammo leaves. Combustions on the other hand only have pressure for a split second so if the barrel is to long it will make a suction and no the ideal combustion C:B ratio isn't .8:1 it is 1.5:1
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King_TaTer
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Tue Dec 19, 2006 12:13 pm

um I guess its alrite. I like the tripod, but everthing else just looks really sloppy to me...I mean cmon dude I know you could have done better than that, It looks like you threw it together in 2 minutes anyway nice gun.
Tshylea
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Tue Dec 19, 2006 7:32 pm

But I did throw it together in 2 minutes! :P
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Insomniac
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Tue Dec 19, 2006 7:44 pm

There isn't really an 'ideal' c:b ratio that works with ALL combustions. One powered by metered propane would need a different c:b ratio than one powered with hairspray. Likewise, a piston valve pnumatic would need a different c:b than a ballvalve pnumatic, because ballvalves open so slowly that less than half the air would be vented in the time it takes a piston valve to completely vent the chamber.
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