Tuning Formula and spreadsheet pic for calculation of efficiency of a PCP is attached (Bar-cc / fpe and fpe/ cubic inch)

[mubhaur]

Formula in the following spreadsheet is showing efficiency.

The efficiency of RAW HM1000X guns in .22 with 18.13 grain JSB and .25 with 34 grain JSB has been calculated in the spreadsheet.

As per this formula the lower the calculated factor, the more is efficiency.

10 is good
Around 12 is average
Below 10 is very good and so on and so forth.

The following sheet reflects the bar-cc/fpe as well as Fpe / cubic inch of air.

In bar-cc/fpe the lower the resultant factor, the more is efficiency.

In Fpe/ cubic inch of air the greater the calculated factor, the more is efficiency.

In case there is any error in it, please guide me.

 

[mubhaur]

The following sheet reflects the bar-cc/fpe as well as Fpe / cubic inch of air.

In bar-cc/fpe the lower the resultant factor, the more is efficiency.

In Fpe/ cubic inch of air the greater the calculated factor, the more is efficiency.

 

[Privateer]

Looks good and checks out in the math.

People should be aware that if they use Open Office instead of Excel, Some spreadsheets will not work.
Depends on the functions used in the Spreadsheet.
=IFERROR(((J4-K4)/B4),"")
Does not fly in Open Office.

 

[Privateer]

I did test an App that I'm doing for this today.
So far that is going great.

 

[mubhaur]

I did test an App that I'm doing for this today.
So far that is going great.

Please share which app ?

 

[darknes]

Formula in the following spreadsheet is showing efficiency.

The efficiency of RAW HM1000X guns in .22 with 18.13 grain JSB and .25 with 34 grain JSB has been calculated in the spreadsheet.

As per this formula the lower the calculated factor, the more is efficiency.

10 is good
Around 12 is average
Below 10 is very good and so on and so forth.

View attachment 415893
The following sheet reflects the bar-cc/fpe as well as Fpe / cubic inch of air.

In bar-cc/fpe the lower the resultant factor, the more is efficiency.

In Fpe/ cubic inch of air the greater the calculated factor, the more is efficiency.

View attachment 415902
In case there is any error in it, please guide me.

Hello. very nice table. I just don't understand the comparison of two calibers with different bullet weights. if you want to compare the use of air in relation to caliber and bullet weight, the same bullet weights must be compared in both calibers. and the result will always be the same. a larger caliber will have less consumption than a smaller caliber and therefore a greater number of shots than a smaller caliber. and the reason is if I give an example: .22 caliber 40 grain will need approx. 170 bar .25 caliber 40 grain will need 130 bar to have approx. the same speed with the same type of airgun and the same volume of air.

 

[weevil]

For regulated guns with tubes rather than bottles, manufacturers may (tend to?) quote tube volumes that include the reg and plenum. It might be good to include a note in your sheet highlighting that issue.

This wasn’t a big deal back in the day before the arrival of enormous plenums.

 

[Bernie7]

Hello. very nice table. I just don't understand the comparison of two calibers with different bullet weights. if you want to compare the use of air in relation to caliber and bullet weight, the same bullet weights must be compared in both calibers. and the result will always be the same. a larger caliber will have less consumption than a smaller caliber and therefore a greater number of shots than a smaller caliber. and the reason is if I give an example: .22 caliber 40 grain will need approx. 170 bar .25 caliber 40 grain will need 130 bar to have approx. the same speed with the same type of airgun and the same volume of air.

EDIT - I initially misread your post and didn’t see that you specified the projectile has the same mass. Gonna go have my morning coffee : )

 

[SpiralGroove]

Hey Mubhaur,
Good information .... which pretty much aligns with the shot count I get in my .22/.25 RAW HM1000x's.

My set-points are lower (.22 = 125 bar) (.25 = 145 bar) and hence using more total air volume for my strings.

I shoot at 915/925 fps in 18.13 and 900 fps with the 33.94's, using a standard valve with Peek poppet and SSG.

 

[mubhaur]

Hey Mubhaur,
Good information .... whic pretty much aligns with the shot count I get in my .22/.25 RAW HM1000x's.

My set-points are lower (.22 = 125 bar) (.25 = 145 bar) and hence using more total air volume for my strings.

I shoot at 915/925 fps in 18.13 and 900 fps with the 33.94's, using a standard valve with Peek poppet and SSG.

My both guns regulator pressure is between 140 and 145 bars.

 

[mubhaur]

Hello. very nice table. I just don't understand the comparison of two calibers with different bullet weights. if you want to compare the use of air in relation to caliber and bullet weight, the same bullet weights must be compared in both calibers. and the result will always be the same. a larger caliber will have less consumption than a smaller caliber and therefore a greater number of shots than a smaller caliber. and the reason is if I give an example: .22 caliber 40 grain will need approx. 170 bar .25 caliber 40 grain will need 130 bar to have approx. the same speed with the same type of airgun and the same volume of air.

I think the formula compensates all these variables.

 

[darknes]

I think the formula compensates all these variables.

if it contains everything as you write, I don't really understand the comparison. i.e. what are you actually comparing in the two calibers? Even if I were to compare any part, I have to have 2 quantities that are the same for both calibers, i.e. example bullet weight + bullet speed = air consumption per shot. or bullet weight + set pressure = bullet power. you probably understand the continuation.

 

[mubhaur]

if it contains everything as you write, I don't really understand the comparison. i.e. what are you actually comparing in the two calibers? Even if I were to compare any part, I have to have 2 quantities that are the same for both calibers, i.e. example bullet weight + bullet speed = air consumption per shot. or bullet weight + set pressure = bullet power. you probably understand the continuation.

I understand that when we compare two different .22 guns with identical projectile, we can get good comparison.

I agree that .22 and .25 vary in air consumption. Hence it doesn't make sense comparing these two. However we can compare two caliber just to find out the difference of air economy.

.22 with identical projectile may be compared to other .22 gun. The same applies to .25

 

[Privateer]

Please share which app ?

I'll share it when it's finished. Still working on it at this time.

 

[darknes]

I understand that when we compare two different .22 guns with identical projectile, we can get good comparison.

I agree that .22 and .25 vary in air consumption. Hence it doesn't make sense comparing these two. However we can compare two caliber just to find out the difference of air economy.

.22 with identical projectile may be compared to other .22 gun. The same applies to .25

so it's not a direct comparison of two calibres, but just a calculation of air consumption. for me it's a rather insignificant figure. more important is the setting of the air pressure, the force of the hammer strike in relation to the weight of the projectile so that it has the ideal speed, the best consistency of speed and also the most accurate hits. after that I find out the number of shots and immediately know how much air I need per shot, even if that figure is ultimately useless to me. if I write it straight, for example, I shoot .25 slug weight 3.45 grams, Bc 0.27, velocity dispersion 288.6-289.3 ms and 106ft/lb at regulator pressure 153 bar. air volume 980cc and 250 bar max= 46 shots per fill.