how do I calculate the tank to barrle ratio?

[cork9]

I just orderd parts to make an over under air cannon. It is going to be a 3" air tank and a 2" barrle. I will have 5' lenghths of each. I want to know how to calculate the tank to barrle ratio so that i can decide how big im going to make it.

[rad14701]

Chamber Volume divided by Barrel Volume should be in the range of 2:1 to 4:1 for optimal performance... Volumes are calculated using the following formula...

Volume = ((Inside Diameter / 2)^2 * 3.1416) * Length

[super spuder]

barrel volume =754 ci
3:1 ratio = chamber volume of 251 ci
length of 3 inch pipe needed= 9 inches long

4:1 ratio= chamber length of 188 inches
length of 3 inch pipe needed=6.6

bottom line. you cant use the hole barrel
*edit* those are B:C ratios (barrel comes first) ensted of C:B

[cork9]

If i used a 3' * 3" tank and a 3' *2" that would be a 1.5:1 ratio right.

[spanerman]

Sorry, i was under the impresion that C:B ratios were null and void on pneumatics....IMHO all the power comes from the flow/opening times of the valve

[super spuder]

it does have some effect. 1017ci chamber
452 ci barrel
=C:B ratio of 2.25:1
oh by the way. just ignore my previus post. i mesed up big time
1696 chamber (whole pipe)
753 barrel volume (whole pipe)
= C:B ratio of 2.25:2
so just use both whole pipes
by the way, sorry about the erlier post, i was tired

[cork9]

so if i use the same lengh of 2" and 3" pipes it would be like 2:1

[dewey-1]

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[super spuder]

yea, i messed up, it was almose 11 so i was getting tired