One question that arrises a lot in the spudgun world is "What is the ideal chamber to barrel (volume) ratio?" Well, it turns out that in the pnuematic world, there is no such thing. The "ideal" ratio will change with the pressure employed, the gas used, projectile fired, and probably the phase of the Moon on your birthday. The point is that every system is different.
Still, the question gets asked and some people have pretty good reasons to ask as they are building guns for specific applications (not just for sh*ts and grins). So with these people in mind (and an evening that would have otherwise been filled with boredom) I threw together an optimization tool of sorts. I do not promise that it fullfills everyone's needs, as those needs will be as varied as the guns people wish to model. Still, I think it may provide quick and easy insight into a gun.
Optimization Method -> Fixed Barrel
This method assumes a fixed barrel length and modifies the reservoir length (and thus, volume) until the acceleration of the projectile as it clears the muzzle is zero. This should result in the most efficient use of the energy available stored in the reservoir given other gun parameters.
Optimization Method -> Fixed Chamber
This method assumes a fixed chamber length/volume and modifies the barrel length until the acceleration of the projectile as it clears the muzzle is zero. This should result in the most efficient use of the energy available stored in the reservoir given other gun parameters. Note that the chamber to barrel ratio derrived will likely be very nearly identical to the ratio derrived by the previous method.
Optimization Method -> Fixed Length
Probably the most useful (in the real world) of the optimization methods, the fixed length method optimizes a gun for maximum velocity with a given overall length. That is to say that if the optimizer adds one inch to the chamber length, it subtracts one inch from the barrel length. This method is particularly useful for opimizing guns of simple construction such as this one.
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