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best chamber to barrel ratio Answered

okay I have not built a cannon yet as such, as I am going to make my first one awesome but I've done some research and found the golden ratio for efficiency for chamber-barrel size, assuming the chamber is always the same volume a chamber is 1.6, now I'm guessing a bit from now on but it seems that that maximum efficiency is approximately 1.61803399 or the golden ratio that keeps appearing in our world, I just thought you guys would like to know for the design stage as this is what I'm going to be using when I make my gun. also is it worth spending extra for a high flow blowgun over a normal one for the pilot valve to my 1" sprinkler or wont it make a noticeable difference P.S. if my calculations are wrong please, if you know more ( I'm only 13) please correct me. I have worked this out from pneumatics, not combustion's or hybrids. expect to see my gun soon!


No a high flow blow gun will not help much. It is only a very small volume of air you are venting. So no.

In regards to you post. Assuming you are only going to 70PSI your formulae is adequate. However I operate a cannon which has a chamber size only half that of the barrel. At 70PSI it does not function optimally. Yet at 170PSI it is another story completley.

thanks I will spend the money I save double sleeving the chamber, thanks for confirming my maths.

. Intuition tells me that chamber pressure will have an effect on the optimum ratio. Maybe not.

this is the max efficiency for 2 chambers of the same pressure and volume of air at 70 psi say you had a 1" barrel and 3" chamber it wouldn't be as powerful as a 1" barrel and 1.5" chamber but the chamber being longer so as to have the same volume, thanks for the comment I should add that I found this at 70 psi and have yet to try efficiency for higher or lower pressures because I was only going up to 70psi as that is when my safety valve starts regulating the pressure, I would take it higher but my parents wont allow it