I've been giving this project some more thought, and I can see why most (if not all) of the competitors have their rifles tethered to a SCUBA or SCBA tank.... First of all, to get 950 fps with the 41.5gr. pellet (83 FPE) and have the valve close when the pellet is half way down a 26" barrel requires about 2800 psi at an efficiency of 0.90 FPE/CI.... That would use 92 CI of air (at 1 bar) per shot.... If you had a 22 CI, 3000 psi tank (2.6 CF), the pressure would drop 61 psi per shot.... If you started at 3000 psi, and shot 7 shots, you would be down to about 2600.... Using less pressure would drop the efficiency, and eventually you wouldn't have enough to get the velocity/energy required even with a dump shot (which is very wasteful).... Sooooooo, it's either not many shots, or a very big reservoir....
If you tethered the same gun to an 88 CF SCUBA tank, you might get about 200 shots from 3000 psi down to 2600.... If you regulated the output to 2800 psi, maybe 100 shots.... The best way to go, would be to tether to a 4500 psi SCBA tank regulated to a 3000 psi output and tune the gun accordingly.... The higher the pressure you use, the more efficient, because you can close the valve sooner.... That also makes the gun quieter, although these things will be LOUD anyway.... In the example above, the residual muzzle pressure would be about 1340 psi (ie nearly half the tank pressure).... Note that these numbers are all rough approximations, and there is no guarantee we can reach the required efficiency levels to produce them.... That said - GAME ON !!!
Bob
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