Recommended Plenum Calculation

[ackuric]

To elaborate more why I use the fudge factor twice instead of just multiplying the square root of the desired fpe by itself, is because one fudge factor I feel is solid when divided by two, the other I think varies differently with caliber+power, have yet to find a way to scale it well, and it will scale differently based on Caliber...that is truly why I need more data points...

ie: for 60 fpe the 3.87 would remain constant on one half of the formula in .25 cal for 60 fpe (3.87 * 60 * 3.87) = 898 , where as on a .22 cal that 3.87 would potentially be something like (3.87 * 60 * 6.6) = 1532 (shot in the dark guess..)

Every caliber will approach a maximum FPE at some point within its limited availability of heavier pellets, once you start reaching for the ceiling, the (2nd) fudge factor is likely to increase. Bigger calibers would scale much less than smaller calibers, of course. So many potential variables go into any of these formulas for this one to be an exact science.

Much like Bob's formula for calculating theoretical maximum fpe in a given port diameter + pressure + caliber...sure it works great, but what if you do identical pressure + port diameter + caliber in a 12" barrel next to a 24" barrel, the formula breaks...does it make the formula useless? No...even if it lacks pellet weight and barrel length and many other variables that are really hard to include in any formula to be EXACT...it is still useful, at least to me..I even modified his formula to INCLUDE pellet weight, and should attempt barrel length but meh...I'll leave that for someone else

[triggertreat]

 

[grand-galop]

This is nothing more than guess work and fuzzy math at its best.  You would be better off just using common sense when tuning than to try and follow this garbage.  JMO
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I think this is growing THINKERING and DEBATE are positive when everyone is not inflating it`s own bubble..  That being said, if it was not from the thinkerers on this forum, we would be LOCKED at the breack barel age..   LOL  And never forget that when a new theory was brought in the science department, the new thinkerer was pointed as BLASPHEMIE OR IRRETIC.. This forum was built for discussions like that..

[trackerbuddy]

"Locked in the brake barrell age".
I think you just called me a knuckle dragger. I don't mind at all, someone needs to be primitive Pete

[ackuric]

This is nothing more than guess work and fuzzy math at its best.  You would be better off just using common sense when tuning than to try and follow this garbage.  JMO

I think this is growing THINKERING and DEBATE are positive when everyone is not inflating it`s own bubble..  That being said, if it was not from the thinkerers on this forum, we would be LOCKED at the breack barel age..   LOL  And never forget that when a new theory was brought in the science department, the new thinkerer was pointed as BLASPHEMIE OR IRRETIC.. This forum was built for discussions like that..

Couldn't have said it better myself. Amen!

[grand-galop]

My point was not to pointing finger at anyone here..  It was just a statement to keep the OPEN MIND on an INEXPLORED TERRITORY... There is something BIGGER than a EGO on this forum. It`s the SHARING and brainstorming that have help the airgun community that is exploding right now..  I remember when I was a kid, the airgun aviable on the market was BARELY GOOD ENOUF to shoot mices.. The LEVEL AND QUALITY that this forum has brought to my knowledge is PRICELESS!!!

[ackuric]

My point was not to pointing finger at anyone here..  It was just a statement to keep the OPEN MIND on an INEXPLORED TERRITORY... There is something BIGGER than a EGO on this forum. It`s the SHARING and brainstorming that have help the airgun community that is exploding right now..  I remember when I was a kid, the airgun aviable on the market was BARELY GOOD ENOUF to shoot mices.. The LEVEL AND QUALITY that this forum has brought to my knowledge is PRICELESS!!!

I concur. I used this method of plenum calculation to hit 60 fpe @ 2k psi from a regulated marauder when many said it couldn't be done. I didn't want to stretch my plenum to 1 CC per FPE and I certainly knew 1/2 CC per FPE wouldn't suffice for me to hit 60 fpe...therefore I crunched a few numbers and shared my results with the community. If it works for you, I am stoked, if not...well it's a theory in progress that is not finalized...air guns have such a WIDE array of requirements/needs that as calibers/power levels go way up, so do certain requirements. If all formulas in life were simple, easy to discover and finalize in timely manners, well....Einstein would have solved every mystery in our universe with as intelligent as that man was...yet...he failed, time and time again as many theoretical physicists do...until he got it right...and even then he still got many things wrong...

[grand-galop]

My point was not to pointing finger at anyone here..

I concur. I used this method of plenum calculation to hit 60 fpe @ 2k psi from a regulated marauder when many said it couldn't be done. I didn't want to stretch my plenum to 1 CC per FPE and I certainly knew 1/2 CC per FPE wouldn't suffice for me to hit 60 fpe...therefore I crunched a few numbers and shared my results with the community. If it works for you, I am stoked, if not...well it's a theory in progress that is not finalized...air guns have such a WIDE array of requirements/needs that as calibers/power levels go way up, so do certain requirements. If all formulas in life were simple, easy to discover and finalize in timely manners, well....Einstein would have solved every mystery in our universe with as intelligent as that man was...yet...he failed, time and time again as many theoretical physicists do...until he got it right...and even then he still got many things wrong...

Matt!!  I encourage you on this path and I will state a phrase that Donald Trump told at a graduation that fit my state of mind so well... { If you have a dream that you have and want to succed, go on until you prove everyone that it is achievable.. Let the haters be your motivation to go forward and at the finish line, let them feed their anger to their lost...} You are definitely onto something that will SIMPLYFIED the way we do the math on calculation for the community.. The variables are hard to implement in the calculation, but, let use your formula for those that want to push the limit of the PCP and double check if it is accurate enouf to be used in lower FPE guns...

[scrane]

My point was not to pointing finger at anyone here..

I concur. I used this method of plenum calculation to hit 60 fpe @ 2k psi from a regulated marauder when many said it couldn't be done. I didn't want to stretch my plenum to 1 CC per FPE and I certainly knew 1/2 CC per FPE wouldn't suffice for me to hit 60 fpe...therefore I crunched a few numbers and shared my results with the community. If it works for you, I am stoked, if not...well it's a theory in progress that is not finalized...air guns have such a WIDE array of requirements/needs that as calibers/power levels go way up, so do certain requirements. If all formulas in life were simple, easy to discover and finalize in timely manners, well....Einstein would have solved every mystery in our universe with as intelligent as that man was...yet...he failed, time and time again as many theoretical physicists do...until he got it right...and even then he still got many things wrong...

Matt!!  I encourage you on this path and I will state a phrase that Donald Trump told at a graduation that fit my state of mind so well... { If you have a dream that you have and want to succed, go on until you prove everyone that it is achievable.. Let the haters be your motivation to go forward and at the finish line, let them feed their anger to their lost...} You are definitely onto something that will SIMPLYFIED the way we do the math on calculation for the community.. The variables are hard to implement in the calculation, but, let use your formula for those that want to push the limit of the PCP and double check if it is accurate enouf to be used in lower FPE guns...

Covfefe!

[grand-galop]

Covfefe!

Like I said previously, LET THE HATERS BE YOUR MOTIVATION!!!!

[K.O.]

Please keep that *&%@SS name off the forum...

[grand-galop]

How could I have knowned  you were so sensitive to that name???   BTW I went back to the rules of this forum and have found nothing wrong with my statement..  MAYBE YOU NEED TO REVISE WHAT YOU ARE READING.. No one is forcing you to read those lines...  RIGHT?

[K.O.]

My dislike goes a long was back and has little to do with to do with our current situation... My father was a crane operator among other things building hotels in Vegas and ask what is thought of him back then... He also in the 90's talked about a very young girl and in his creepy way said

"I will be dating her in ten years"... do you want to hear what he has said about his own Daughter..? So yep I have a deep dislike of him...

You bring him up referencing him at a Coast guard commencement( by the way you misquoted) in which he makes it about him and how he has been mistreated... Not about them and their achievement...

So yeah I do think it is bringing politics into somewhere it does not belong...

 about how you guys attack Bob  for saying without better explanation I do not want to be connected to this method of figuring... he was not attacking just stating his position... So who then made a personal attack on Bob... saying if it was the other way he would be the first to take credit...

so yep I object to what you are bringing into this...

[triggertreat]

My dislike goes a long was back and has little to do with to do with our current situation... My father was a crane operator among other things building hotels in Vegas and ask what is thought of him back then... He also in the 90's talked about a very young girl and in his creepy way said

"I will be dating her in ten years"... do you want to hear what he has said about his own Daughter..? So yep I have a deep dislike of him...

You bring him up referencing him at a Coast guard commencement( by the way you misquoted) in which he makes it about him and how he has been mistreated... Not about them and their achievement...

So yeah I do think it is bringing politics into somewhere it does not belong...

 about how you guys attack Bob  for saying without better explanation I do not want to be connected to this method of figuring... he was not attacking just stating his position... So who then made a personal attack on Bob... saying if it was the other way he would be the first to take credit...

so yep I object to what you are bringing into this...

It is easy to cherry pick anyone's life.  No one can throw stones honestly.  I am very pleased with the current situation, but understand clearly that no one really has any control over the situation.

[K.O.]

It was a veiled way of bringing politics where it does not belong... and there was a personal attack on Bob's integrity...

[grand-galop]

It was a veiled way of bringing politics where it does not belong... and there was a personal attack on Bob's integrity...

Kirby!!!   I would suggest you to clean your personal life before being consumed with your anger on someone.... Your last 2 comments are too irrational to be linked to the subject of discussion.. To be CLEAR OF ANY MISINTERPRETATION, I mention that I was not pointing any finger at anyone...  It is too often that the moderators has to intervine in topics because of guy like you.. The QUOTE I PICK was to encourage and motivate Matt.....   NOTHING POLITICAL HERE!!!   Am I clear enouf...  Grow your skin a little and make your life less miserable.

[rsterne]

Kirby, just let it go.... Alain's comments about me don't concern me in the least, nor do Matt's.... GTA Members are smart enough to wade through the nonsense....

Bob

[ackuric]

Bob gave me ADDITIONAL numbers as I originally obtained my constant (.96) by doing some math on some figures provided by Robert Lane on his website to obtain how much available energy there is for 100 psi per 1 cc of volume (during adiabatic expansion), albeit at the time I didn't know Robert Lane used a constant for a common regulated pressure of around 1900-2000, where Bob had informed me that the available energy (during adiabatic expansion) changes as pressure goes up or down, I then requested the numbers from him (which he obtained from a website) for various psi ranges to make my calculation more accurate for different pressure ranges and he obliged...

No one attacked Bob, in fact read what he stated very clearly....

I'm not saying it works or it doesn't.... but please don't assume that because I gave him some numbers (for what he keeps telling me is a totally unrelated subject, yet he uses them).... that I endorse this method or not.

Bob has been/is and will likely continue to be a great contributor to the air gunning community...he likes to receive credit where its due...I know that HE knows that this method of obtaining plenum volume requirements is onto something...you can CLEARLY read it in his wording, besides I have no qualms with his stance or his lack of will to participate and help develop such a novel idea / concept, even if by entirely different means...but know this. Mark my words! There is a way to successfully calculate an OPTIMAL plenum volume, maybe we won't have enough information to fully develop it for another hundred years, so what if my attempt ends up being entirely wrong...so far my data seems fairly good for .177/.22/.25 calibers at least at the power levels that make sense...I know it'll require further development for big bores...just as Lloyd's amazing internal ballistic spreadsheet has likely seen dozens if not HUNDREDS of revisions to make it better or correct previous mistakes, so would a formula/spread sheet like this...

I am in no way trying to compare myself to Lloyd with the above statement...it's just a fact, especially in this line of work...which I am NO expert or professional in such as Lloyd.

-Matt

[K.O.]

Once again a personal attack... now towards me and my failings...

... I suggest you look at how you are saying things...

No anger from me but I do see how you are saying things as disruptive...and  funny how no one else quotes political figures here I guess they realize it is unnecessary and counter productive...

It is not irrational to see your words towards Bob and now me as personal attacks...

Take some responsibility for your words...

Have I insulted you... NO...  I DO HOWEVER DO OBJECT TO YOUR PERSONAL ATTACKS...

[K.O.]

Kirby, just let it go.... Alain's comments about me don't concern me in the least, nor do Matt's.... GTA Members are smart enough to wade through the nonsense....

Bob

sorry you are right... tis a waste of time...subtle disrespect for the rules and not so subtle disrespect from Alian towards you got to me...