90bar, hammer spring max setting
120bar, hammer spring medium setting
Assuming both is giving the same velocity?
120bar, hammer spring medium setting
Assuming both is giving the same velocity?
Which of these two settings is more efficient (more shots)?
- Thread starter _walter_
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Well, I guess the valve is going to release all the air in the plenum, so, it seems the lower pressure would yield the higher shot count. But, neither may yield the greatest consistent shot count, which gets to the matter of balance between pressure and hammer tension.....I think.
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More efficient and higher shot count are actually mutually exclusive. Maximizing one sacrifices the other.
For the most part the lower regulator pressure will yield higher shot count, and the higher pressure will yield higher efficiency.
So for example, whereas high pressure & short valve dwell will indeed give higher efficiency, that does not necessarily translate into higher shot count because you have a shorter pressure range to work with before it drops below the regulator’s setpoint.
The working assumption here is that the hammer strike is adjusted correctly. For any given regulator setpoint and porting, there is an optimal hammer strike that will yield the best consistency, and that comes at about 95 – 97% of peak velocity. If instead you really lean on the valve to get that last 3 – 5%, efficiency will plummet and you may get poorer shot count.
Or if you choose to operate it way below peak velocity, you can get very high efficiency. For example, downtuning from 900fps to 700fps by simply backing off the hammer strike will do that. The result is super short valve dwell which means only a teeny tiny sip of high pressure air is released. However what is happening is the system is operating at partial valve lock and consistency will be negatively impacted, giving you a high extreme spread.
The reason a larger plenum improves shot count is because there is a pressure drop in the plenum during the shot cycle. Having a larger volume of air minimizes this pressure drop, holding a higher average pressure during the shot cycle. So whereas with a smaller plenum you may have needed to use a very high regulator setpoint to compensate for the pressure drop, with a larger plenum you can lower your setpoint and still maintain the same average pressure during the shot cycle, thus increasing the useable pressure range.
For the most part the lower regulator pressure will yield higher shot count, and the higher pressure will yield higher efficiency.
So for example, whereas high pressure & short valve dwell will indeed give higher efficiency, that does not necessarily translate into higher shot count because you have a shorter pressure range to work with before it drops below the regulator’s setpoint.
The working assumption here is that the hammer strike is adjusted correctly. For any given regulator setpoint and porting, there is an optimal hammer strike that will yield the best consistency, and that comes at about 95 – 97% of peak velocity. If instead you really lean on the valve to get that last 3 – 5%, efficiency will plummet and you may get poorer shot count.
Or if you choose to operate it way below peak velocity, you can get very high efficiency. For example, downtuning from 900fps to 700fps by simply backing off the hammer strike will do that. The result is super short valve dwell which means only a teeny tiny sip of high pressure air is released. However what is happening is the system is operating at partial valve lock and consistency will be negatively impacted, giving you a high extreme spread.
The reason a larger plenum improves shot count is because there is a pressure drop in the plenum during the shot cycle. Having a larger volume of air minimizes this pressure drop, holding a higher average pressure during the shot cycle. So whereas with a smaller plenum you may have needed to use a very high regulator setpoint to compensate for the pressure drop, with a larger plenum you can lower your setpoint and still maintain the same average pressure during the shot cycle, thus increasing the useable pressure range.
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I woted for the 120 bar option. The reason being you are wasting air when hammer is maxed out at lower pressure.
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But there is many unknown variables. If the hammer is like 95-97% of peak, as nervosstrig talked about, the 90 bar might get more shots, as you do not have to stop shooting at 120 bar (to prevent velocity increase). But that also depends on the maximum fill pressure of the gun. If the gun has a max fill pressure of 200 bar, and you stop shooting at 120 bar reg, the 90 bar reg allows you to shoot lower down before you have to stop. But if the gun fills to 300 bar, and you stop at 120 bar, the 120 bar reg probably wins, as even you stop at 120 bar, each of thouse shots will use less air.
In a practical scenario, you can probably shoot the 120 bar reg setting, off the reg, down to 110-100bar, before any big increase in velocity apears, and you have to stop. In that case the 120 bar setting is probably a winner.
In a practical scenario, you can probably shoot the 120 bar reg setting, off the reg, down to 110-100bar, before any big increase in velocity apears, and you have to stop. In that case the 120 bar setting is probably a winner.
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Here's the formula for converting total air usage into airgun efficiency. Efficiency changes relative to the gun's tune and projectile weight.
*Total PSI of air used ÷ 14.5 = Bar
*Bar × total Cubic Inches of air cylinder volume = total air used
*Total air used ÷ calculated PFE of current tune and projectile = X
*Total number of shots fired ÷ X = Efficiency in PFE per Cubic Inch
.75 is poor,
1.0 is still fairly poor,
1.5 is very efficient.
*Total PSI of air used ÷ 14.5 = Bar
*Bar × total Cubic Inches of air cylinder volume = total air used
*Total air used ÷ calculated PFE of current tune and projectile = X
*Total number of shots fired ÷ X = Efficiency in PFE per Cubic Inch
.75 is poor,
1.0 is still fairly poor,
1.5 is very efficient.
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If the hammer was maxed out at 90 bar, I would guess the optimal pressure would be around 100-110 bar, without going into calculations.
I know there was a guy here on the forum doing test on a FX gun, and he came up with +20 bar from the speed you get at maxed out setting. That means you add 20 bar from the speed you have at max hammer, and then increase the hammer until you get the same speed as previous maxed out. That should get you the most shots, at that particular speed.
I know there was a guy here on the forum doing test on a FX gun, and he came up with +20 bar from the speed you get at maxed out setting. That means you add 20 bar from the speed you have at max hammer, and then increase the hammer until you get the same speed as previous maxed out. That should get you the most shots, at that particular speed.
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It would depend on the gun as well if you can control the dwell length of time like on the impacts it can make a difference to
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I bokmarked the original test https://www.airgunnation.com/thread...t-count-without-forgetting-precision.1169023/
He used 3 different guns with differrent barrel lenghts, all being FX guns. But there will probably be some differences on some other guns.
Still think it is a nice test, as he did testing in 5 bar increments. All credit to broekzwans doing this test.
I qouted him a litle wrong. When I reread the thread, he concluded the best pressure was 20% higher, not 20 bar higher. But I remembered it close enough
Original qoute: "maximum shot count is achieved at a pressure around 20% higher than the minimum required pressure to reach the velocity."
I personally have no intention to test this myself, but I think it is a nice guideline.
He used 3 different guns with differrent barrel lenghts, all being FX guns. But there will probably be some differences on some other guns.
Still think it is a nice test, as he did testing in 5 bar increments. All credit to broekzwans doing this test.
I qouted him a litle wrong. When I reread the thread, he concluded the best pressure was 20% higher, not 20 bar higher. But I remembered it close enough
Original qoute: "maximum shot count is achieved at a pressure around 20% higher than the minimum required pressure to reach the velocity."
I personally have no intention to test this myself, but I think it is a nice guideline.
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