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Old 04-02-2013, 07:25 AM   #31 (permalink)
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I think its been posted somewhere but I can't find it. Do we know the joules per gram of CO2? As in, what the maximum potential joules we can get from a 12g?
There are different options on that question what type of calculation should be used... und how he should be best/corectly performed. But I have confidence in that method what comes from laws of preservation of energy / state of gas equation (I thinkt that he has been mentioned here on MCB in thread "Snipers on 12g the reg" or something like that - it was generally very good thread - but I have seen aplication of this method even on different place with CO2 airguns, and with CO2 tanks in industry with the same results) and this method leads us to result that in room temperature there are ideally stored 1080 Joules in one powerlet (when are there really 12 grams of CO2, what are commonly not - some powerlets having real fill only 10 grams... - but BTW surprisingly it look so that practically this difference do not affects the results how you could expect... the powerlets with measured 10g a 12g real fill having surely not 20% differences in performance - ...and you have everytime possibility that the weight difference between the full and empty powerlet was not only CO2, but some gram is perhaps some "dirt" water wapours or oil).

So when we speaking here now about efficiency record results with 450-550 Joules, that should corespond with 42-51% efficiency.
So there can be still a lot of room for further improvement : -). Theoretical 100+ shots on 250 fps per powerlet (marker with 90% efficiency with 1080 Joules in powerlet) will be great : -).
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Old 04-02-2013, 09:31 AM   #32 (permalink)
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Awesome info, thanks. I'm going to be doing some tuning this weekend with a redux and will post some info here.
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Old 04-02-2013, 09:38 PM   #33 (permalink)
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Got a chance to get some shots in this afternoon. I posted my results in the Redux section here:

VKC Duck #51 tuning thread
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Old 04-02-2013, 10:05 PM   #34 (permalink)
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.
Blah,

Weighing, then counting, a bag of ~30balls is easy enough IMHO. What kind of paint are you using that can absorb >0.1g of water in the five minutes it takes to shoot?

Not measuring paint can add ~15% error. Using average velocity in your calculations another ~3%. Nearly the entire 'best' list is within the sum total margin of error. What kind of comparisons of value can be obtained from such 'big inaccuracy' data that can't be obtained from simple offhand overgeneralized statements? e.g. "The old PGP is inefficient".

Calculating the KE of the projectile is an accurate method of measuring energy-out. Energy-out is a valid way to then measure total efficiency. Calculating KE from measured values does not put ANY inaccuracy into the KE value. If something could be done to improve efficiency, that is irrelevant to the efficiency calculation. If marker A could be more efficient shooting at a velocity closer to marker B, that doesn't make the efficiency calculation any less valid. It is only in the comparison of these efficiency numbers does that data matter. Considering the large margin of error in the data, I don't think anyone can make much of a comparison anyways.

Can you elaborate on how you arrived at that 1080J number?
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Old 04-03-2013, 10:22 AM   #35 (permalink)
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Blah, ...
The main thing behind is, that when the user of the paintgun makes eff. tunning, then he uses commonly the same balls from one sack (or from one crate) for the following tests and he is mainly not interested about comparsions with others - he will simply "only" raise efficiency of his marker, step by step, while he uses the same balls, so he needs not know the weight of given paintballs.

So for tunning it is not necessary know the ball weight... but you are right that for comparsion user x user, marker x marker it will be good, we should weight the balls... It is not such complicated, and especially for accuracy of such like KE calculations it will be better. Even when we can not get the ball weights for all tests (because we having problems get even alone velocity graphs from some peoples), it will not harm to know the weights at least in some tests.

But again I do not think that it helps us a lot to know the weight. Physics is physics, but in reall world he is more complicated than KE=v*v*m/2. Influence of the difference in weight of the paintballs is imho not so big as others factors connected with paint, which you can not measure so easily. We all know that even with the in super-consistent CA marker you can easily have deviations up to +/- 10 fps (total 20 fps, when is the velocity 300 fps is that 6.7% difference) between shoots with the same paintballs from one sack, sometimes... Imho the differences in dimension accuracy of the paintballs and thier ability to seal without add lot of friction (elasticy and roughness and hardness) plays bigger role than common - let we say total 10% differences - in weight.

But along my personal experiences - from the moments in which I have swichet one paint for different - it do not looks for need of such like precision. Paint is the most important factor for shooting accuracy, but when we speak about efficiency, then the marker seems to be more important (at least if you have similar paint to bore match, what can be handled by suitable barrel). Perhaps thanks to that fact, that the differences are commonly not extreme, I do no know.


In theory all good calculations giving the same results. But practically... imho the way how is efficiency calculated everytime affects the results a little bit. Imho with these KE calculations are the lower fps little advantaged, because efficiency of transfer of the energy into the ball moving at highter velocities will be everytime lower than in lower velocities. ...even when we do not taking in concert that the slower moving ball will stay in barrel longer and you have more room work with him efficiently with bad timed valve. So marker tunned for lower velocity will be here look to be more efficient than the tuned for highter velocity. The question is how big are the differences here, when the low velocity is for exception 240 fps and the big 320 fps.


1080J: it is explained by others for exception here: Theoretical maximum shots per 12g?
I have controled that independly around industry safety calculations, focused on that how potential dangerous can CO2 tanks be.

Last edited by 3022; 04-03-2013 at 10:53 AM.
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Old 04-03-2013, 10:26 AM   #36 (permalink)
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I'll try and get some numbers for you when I get home in a month from my collection of carters, I have a few buzzards, comps etc.
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Old 04-03-2013, 10:37 AM   #37 (permalink)
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All of those numbers in the halfass chart do NOT have a reg. Straight spring tuning.
Interesting. You were able get out of your Sterling 347 Joules without reg, safely below 300 fps and with decent cosistency. With my - imho - allround well tuned P68SC I was not able get such like result.

I have put your results in following Excel Table: http://www.pgp.mysteria.cz/docasne/o...g_Sterling.xls

Last edited by 3022; 04-03-2013 at 10:49 AM.
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Old 04-03-2013, 10:48 AM   #38 (permalink)
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Got a chance to get some shots in this afternoon. I posted my results in the Redux section here:

VKC Duck #51 tuning thread
~323 and ~283 Joules of KE. Not bad. Thank you for input.

Best know result from Redux what I have is seen are short304s 335 Joules - not to far.
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Old 04-03-2013, 11:06 AM   #39 (permalink)
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~323 and ~283 Joules of KE. Not bad. Thank you for input.

Best know result from Redux what I have is seen are short304s 335 Joules - not to far.
Cool. I'm sure I can do better. I'm still playing around with the springs.
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Old 04-13-2013, 11:42 PM   #40 (permalink)
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I got a lot more numbers for you to look at including some pretty nice total shots (not at field velocities) but the counts are nice.

VKC Duck #51 tuning thread
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