Air usage Efficiency Calculator for PCPs ??? (another calculator added 9/7)

[rsterne]

You are showing nearly a plateau in velocity as you increase the hammer preload past 3 turns, so I would back it off to there and call it a day.... I'm guessing the efficiency will jump up to about 1.0 FPE/CI or maybe even more at that setting....

Bob

[Bent]

You are showing nearly a plateau in velocity as you increase the hammer preload past 3 turns, so I would back it off to there and call it a day.... I'm guessing the efficiency will jump up to about 1.0 FPE/CI or maybe even more at that setting....

Bob

I agree, I'll be testing the shotcount for 2 and 3 turns on the screw over the next couple of days.. 
And what i want is that the heavier pellets, 16grain and up should be around 270m/s. Thats the best speed for pręcision for most heavy pellets from what I have tested.

[rsterne]

That may be so, but you may not be able to achieve that without upping the regulator setpoint.... If you try and achieve too much with too much hammer spring proload combined with too low a pressure, your efficiency, and shot count, will suffer....

Bob

[lloyd-ss]

Bob,
I am glad you have all these handy rules-of-thumb figured out.  They are always helpful.
Lloyd

[rsterne]

IMO, the greatest tool for tuning a regulated PCP is to graph the velocity vs. hammer spring preload.... You will get a curve such as this....



Once you are on the velocity "plateau", adding hammer strike only wastes air.... I always tune my regulated guns to operated on the "knee" of the curve, which in that graph would be at 5 turns out.... Increasing the preload 2.5 turns (0.1") would only gain 20 fps and use over twice the air, getting less than half the number of shots....

Bob

[Bent]

Been out in the wonderfull sunshine, with a buddy and two of my friends(HW110 and Cometa)

Still need to fill out a few numbers but it seems like the optimal setting for the Cometa LYNX would be around 2½ turns of the screw... 
That also makes sense, as the same "engine" is sold as a .25

Thanks to rsterne and Lloyd.. 

[rsterne]

By that graph, anywhere from 2.5 to 4 turns should be OK, it's a matter of how badly you want power vs. shot count....

Bob

[lloyd-ss]

By that graph, anywhere from 2.5 to 4 turns should be OK, it's a matter of how badly you want power vs. shot count....

Bob

Yes, the "Greed for Speed."  I have it bad, but I know I am not alone.