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C:B ratio

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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C:B ratio

Unread postAuthor: Mattmp36 » Thu Feb 28, 2008 12:19 pm

I have been trying to develop plans for a new spud gun. I am a little unsure if my calculations are right though. I thought of a 4 x 12" CC and a 1.5 x 60" barrel. I tried to do the math and I came up with a ratio of about 1.5:1. Am I close or way off?
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Unread postAuthor: jimmy101 » Thu Feb 28, 2008 2:01 pm

The simplest equation to calc CB ratio of your guns is just:
(4*4*12)/(1.5*1.5*60) = 1.4222
(2*2*12)/(0.75*0.75*60) = 1.4222

V<sub>chamber</sub> = (Pi)(r<sub>chamber</sub><sup>2</sup>)(L<sub>chamber</sub>)
V<sub>barrel</sub> = (Pi)(r<sub>barrel</sub><sup>2</sup>)(L<sub>barrel</sub>)
Where r is the radius and L the length.

The CB is V<sub>chamber</sub>/V<sub>barrel</sub>
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