Step 9: Operation and Performance
On my launcher, the minimum operating pressure is about 20 PSI. Keep this in mind; if your supply of gas is less than your operating pressure, the gas can leak out. This would be really dangerous if you used a gas like CO2 in a closed space, not to mention frustrating as all of your compressed gas would be gone.
As far as performance goes, there are a lot of factors that come into play when dealing with distance, speed, etc. With the launcher itself, performance is really maximized by eliminating dead space - the space "in between" critical elements of the launcher. For example, the more space you have between your projectile and the main valve, the more your cannon's performance suffers. Moving the projectile as close as possible to the valve will result in greater power and acceleration. Since we used cam-lock fittings on this launcher, the performance will indeed suffer a little bit. However, I think the added functionality of the cam-lock fittings far outweighs the decrease in performance. Likewise, one needs to eliminate space between the main valve and the pilot valve. In this case, we did about the best we could, since the QEV and the DCV are back to back.
If you think you want more power, you could always increase your operating pressure or get a bigger secondary chamber. I would recommend this if you were planning on launching large objects (larger than golf balls) over far distances. Just remember that you won't get as many shots out of the same CO2 tank as a launcher with a smaller secondary chamber. My choice of 2"x10" was "middle of the road" in that I can shoot golf ball sized objects as well as smaller things without penalizing myself in CO2 usage.