A loss in efficiency? I would think a certain amount of energy is lost here?


"i never was much for book learnin"

...which (some say) is actually a good thing.

Steve

Was just thinking about valves behind the pellet as oppsed to below.


"i never was much for book learnin"

like the Condor have a straight through valve system.... If done properly, it can also result in a larger transfer port than what can be achieved from below.... The Crosman style works fine up to about 75% of the bore (maybe 80%) for the barrel port, and then it is likely you will have loading problems.... In theory, having the air come from behind, you should be able to have a bore size passage all the way from the valve....

Sharp corners are never good, but changes in direction don't seem to bother flow too much.... and are pretty much necessary in most port designs, even in F1 racing engines.... However, just so I don't get misquoted (again), restrictions are never a good idea when you are striving for maximum power.... In most cases they are a necessary evil, so we simply live within the constraints of a given design, and do the best we can....

Bob

a daisy 717, a daisy 853, and a P-17..all SSP designs, but both the daisy guns have bolt probes and barrel ports, with the convoluted flow path forced by an O/U stacked design.

The P-17 isn't quite inline, but close..no probe, no port,and a relatively straight flow path..with a long barrel, it can make as much power as the daisy rifle, from about half the air volume, and will easily beat the Daisy pistol, even with it's shorter barrel.

This suggests to me that there is a significant loss of energy in the typical O/U design.

Well, I think it's the relative shortness of airpassage which makes P-17 effective in relation to bolt guns in comparison between single stroke pump pneumatics. There is such a small amount of air, that there's no way to transport it via passages without great loss.

Once there was one guy who claimed he had a special cartridge firing big bore in the lines of brocock air cartridges. He never posted any evidence but claimed that his gun was super efficient compared to ordinary big bores.

...they account pretty well for its higher efficiency.

Steve