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Post by X on Jun 24, 2014 18:27:11 GMT -5
True. I was just thinking about it from a rules point of view. Since we are talking about this, I really wonder what the pain difference is between a .40 and a .20 with equal energy. This is another thing that I think everyone is going off of an educated guess but not necessarily actual objective (or at least as objective as pain based observations can be) testing.
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echo5
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Post by echo5 on Jun 24, 2014 19:32:40 GMT -5
Pain is a subjective physical reaction. Example. I use to fight in the ring. I got use to getting hit, and it doesn't bother me as much as a bee sting does. Being stung hurts like hell to me, but might not to someone else. So the difference in how a .20 feels as to a .40 is subjective and not accurate. However, if you did that same test lets say against a wood plank to see what kind of impression each round makes in the board it may give you a better idea of how players will feel when a round hits them.
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Post by X on Jun 24, 2014 22:37:15 GMT -5
The wood test is not really analogous to human skin though. We need some pig skin.
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Post by Puma1 on Jun 24, 2014 22:56:08 GMT -5
The wood test is not really analogous to human skin though. We need some pig skin. Sent from my XT1080 using Tapatalk Let's Mythbusters this shit. I work at the meat department for Meijers. I'll see what I can do. Worst comes to worst, I volunteer as tribute. Let's just keep it under 1.25 J's please.
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Post by blackhawkranger on Jun 25, 2014 6:26:25 GMT -5
Hope you don't mind me jumping in with a question here as P*'s are pretty much non existent over here in the UK so please forgive my ignorance... So I keep seeing you guys saying you've got to measure the joules not fps right? But I dont fully understand why. I would of thought (prehaps wrongly) if you have: aeg chrono at 350fps using .2's And P* chorno at 350fps on .2's Both would give out the same reading in joules(1.13) right? Now lets assume absolutely nothing is adjusted in either system except we load each with a mag containing .25's instead of .2's... Aeg chrono at 313fps with .25's And P* chrono at 313fps with .25's Each system will still give the same reading in joules (still 1.13) right? (Well at least so damm close you'd have to be one anal mofo to complain about it ) So what I'm asking is isn't it a case of using a bb weight/FPS chart like we have? For instance.... 350fps on .2 = 1.13 joules 313fps on .25 = 1.13 joules 286fps on .3 = 1.13 joules 247fps on .4. = 1.13 joules 239fps on .43 = 1.13 joules So if a P* passes chrono of 350fps on .2's I can't see why it wouldn't be under 239fps on .43's? (without any tampering obviously). But lets say there's something I dont understand (like this "creep" business) if you chrono using the weight they are going to play with and ensure its under the above limits right? Same thing but US applicable 400fps on .2 = 1.48 joules 358fps on .25 = 1.48 327fps on .3 = 1.48 283fps on .4 = 1.48 273fps on .43 = 1.48 ooooooor am I missing something??
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Post by X on Jun 25, 2014 6:40:06 GMT -5
What you're missing is the theory that the heavier BB will accelerate slower in the barrel thus it would be accelerated for a longer period of time increasing the total energy.
As of yet we don't know how much additional energy a BB that is twice as massive might receive.
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Viper
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Post by Viper on Jun 25, 2014 8:29:06 GMT -5
Blackhawkranger, you are sort of correct with your statements. Yes the speed and mass of the bb will give you the same energy readings regardless if it is a P* or an AEG or a GBB. However, it's when people change weights of bb's AFTER chrono that the velocity doesn't drop at the same rate in a P* vs an AEG. This is where the problem lies. If everyone were to chrono with .2's as was the convention years ago (and still is at some fields) you get Joule creep because of the difference in platform and air "properties".
Like when people convert an AEG's FPS from .2 to .25 to .3 it might be: 350fps on .20 = 1.13 joules 313fps on .25 = 1.13 joules 286fps on .30 = 1.13 joules
But being that the air "properties" in a P* CAN affect the FPS reading differently (is that generic enough wording? haha) It may be: 350fps on .20 = 1.13 joules 330fps on .25 = 1.26 joules 310fps on .30 = 1.33 joules
These are theoretical numbers that I pulled out of my ass. But that's basically what MAY occur. So many things can affect this in a P*. Barrel length, FCU settings, etc...
I was not able to do any testing last night because the weather kept spitting rain at me whenever I grabbed my gear. Hopefully tonight I will have some better concrete numbers to test this theory.
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Post by Gimpalong on Jun 25, 2014 8:55:23 GMT -5
Angus (one of the guys from Amped) did some experimentation back in 2012 and posted his results on the PstarTalk forum. Why does energy/joule creep occur? ...and for God's sake I'm not an expert, but this is my understanding, and please correct me if I'm wrong... The theory, as X succinctly described it, is that a heavier BB takes longer to be driven out of the barrel by the air being pushed by a piston (in AEGs) or released by the poppet valve (in P*s). In a perfectly tuned air gun, the amount of air released on firing should accelerate a BB to its maximum speed so that it reaches that maximum speed at the very end of the barrel. In this situation, the entire length of the barrel behind the BB is filled with air. This means that the gun is properly "volumed," or that the air being pushed out is matched to the length of the barrel. In an "under volumed" gun, the air released by the gun itself accelerates the BB so that the BB reaches its maximum speed before the end of the barrel. So if the barrel is 300mm long, the BB might be reaching its maximum speed after passing 200mm or 250mm down the barrel. So the BB has stopped accelerating before it leaves the end of the barrel. In an "over volumed" gun, the BB is still accelerating when it leaves the barrel (?). Or hasn't reached its potential maximum speed, if, say, the barrel were longer. Neither situation is very efficient as in the first case too little air is being used and in the second case too much air is being used. Now how a gun is "volumed" depends on the length of the barrel, the weight of the BB and the amount of air being pushed down the barrel. In AEGs, the amount of air being pushed out of the gun is controlled by the cylinder (remember some have no hole while others have holes at different positions along the cylinders length?). In P*s, the amount of air being released is controlled by the poppet valve, which is in turn controlled by the FCU which can be adjusted to hold the poppet open for longer (more air released) or shorter (less air released) periods. This is accomplished through the "DP" setting on the FCU. So while on an AEG voluming requires messing with cylinders, P*s can adjust air volume "on the fly" via the FCU. If a gun with a 300mm barrel is properly "volumed" with .20s, that same gun will be "under volumed" (with .20s) if the barrel is lengthened to 400mm. Likewise, if a gun is properly "volumed" with .20s (i.e. a .20 BB reaches its maximum speed as it reaches the very tip of the barrel and exits the gun) then it will be "under volumed" for a .25 (the .25 will have reached its maximum speed before the end of the barrel). Energy creep occurs when a gun changes from an inefficient, over- or -under volumed set-up (either by changing barrel length, the amount of air put out, or the BB weight) to an efficient, properly volumed set-up. For example:I have a gun with a 300mm barrel that is over-volumed for a .20 BB. My .20 BB is so light that the air being pushed down the barrel drives the BB out of the barrel before the BB can reach its maximum speed. Air is wasted along with the extra energy it carries. I chrono my rifle at 390 FPS (1.45ish joules) with my .20 BB. I'm "good to go" to play as my field's maximum allowable energy level is 1.5 joules (400 FPS with .20s). I load a magazine with .30 gram BBs. Now my gun is "properly volumed" (i.e. over-volumed for .20s) so that the .30 BB is reaching its maximum speed at the very tip of the barrel. So when I shoot my rifle with a .30, the .30 since it is heavier than the .20, takes longer to travel down the barrel and the full amount of energy of the air being pushed out of my gun is "absorbed" (probably not the right term) by the BB. As a result, when I chrono with .30s, my overall FPS will be lower, but the amount of energy I'm imparting to the BB will actually be higher and consequently my gun may break the field maximum energy limit of 1.5 joules. Phew, confused? I sure am. TLDR:
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Post by Stinger on Jun 25, 2014 9:05:41 GMT -5
Pain is a subjective physical reaction. Example. I use to fight in the ring. I got use to getting hit, and it doesn't bother me as much as a bee sting does. Being stung hurts like hell to me, but might not to someone else. Likewise, a bee sting is nothing to me. My family has a small honeybee farm as a hobby (hence, my callsign "Stinger"). I've been stung more than I can count. I'm so used to it that I would much rather be stung than be shot by a 1.75J+ airsoft BB. Part of it is because my body has adapted to the venom, part of it is just mental. So, how does this apply to our conversation? Pain is not an accurate measurement of imparted energy. Polarstars should be chronographed at the heaviest possible weight BB due to energy creep (described very well above by Gimpalong).
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Post by Puma1 on Jun 25, 2014 9:14:27 GMT -5
It does actually make some sense.
If the table posted above is correct, AEG's are generally over volumed for the .2's and under volumed for the .3's.
In a polarstar, their is no real over/under voluming. Instead of a parabola shape it's a constant (or close to it) function.
Let me see if I can crunch some numbers later tonight and get a working chart to equalize Joule creep with an AEG's FPS chart.
It's probably not going to be pretty, so don't hold your breath.
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Post by Stinger on Jun 25, 2014 9:24:00 GMT -5
If the table posted above is correct, AEG's are generally over volumed for the .2's and under volumed for the .3's. Which is why most of us who know what we're doing us 0.25-gram BBs, or 0.28s. The reason that Polarstars are so dangerous in this regard is that it's far easier to optimize volume on a Polarstar after chronographing (for obvious reasons) than it is to change out the inner barrel/compression components on an AEG. Which is, again, why we need to chronograph P*s with high-weight BBs to negate this possibility as much as possible. From there, you can spot-check P*s on the field as Mosin has so often stated is a necessity.
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echo5
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Post by echo5 on Jun 25, 2014 9:24:55 GMT -5
Pain is a subjective physical reaction. Example. I use to fight in the ring. I got use to getting hit, and it doesn't bother me as much as a bee sting does. Being stung hurts like hell to me, but might not to someone else. Likewise, a bee sting is nothing to me. My family has a small honeybee farm as a hobby (hence, my callsign "Stinger"). I've been stung more than I can count. I'm so used to it that I would much rather be stung than be shot by a 1.75J+ airsoft BB. Part of it is because my body has adapted to the venom, part of it is just mental. So, how does this apply to our conversation? Pain is not an accurate measurement of imparted energy. Polarstars should be chronographed at the heaviest possible weight BB due to energy creep (described very well above by Gimpalong). X had stated about the pain difference between a .20 and .40. That's how it pertained the overall question of this thread. Look one line above the one I posted, and you quoted, and you will see why I posted that response.
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Post by Stinger on Jun 25, 2014 9:37:51 GMT -5
Likewise, a bee sting is nothing to me. My family has a small honeybee farm as a hobby (hence, my callsign "Stinger"). I've been stung more than I can count. I'm so used to it that I would much rather be stung than be shot by a 1.75J+ airsoft BB. Part of it is because my body has adapted to the venom, part of it is just mental. So, how does this apply to our conversation? Pain is not an accurate measurement of imparted energy. Polarstars should be chronographed at the heaviest possible weight BB due to energy creep (described very well above by Gimpalong). X had stated about the pain difference between a .20 and .40. That's how it pertained the overall question of this thread. Look one line above the one I posted, and you quoted, and you will see why I posted that response. Oh right So due to the increased mass of the 0.40-gram BB, it has more inertia. Thus, it takes more force to change its velocity. Which means your body has to supply more force to "deflect" the round when it hits you. Every force has an equal and opposite force, so a 0.40-gram BB hits you with more force than a 0.20-gram BB holding the same energy. Is my physics correct?
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Post by X on Jun 25, 2014 10:26:45 GMT -5
Well there's kinetic energy and momentum. Assuming the force applied is the same between a .20 and a.40 (which is not true in an airsoft gun) the .40 will have less KE and more momentum (as I understand it). I'm not sure which would translate to more pain / damage. I brought it up only because we're not specifically trying to limit energy. If my BB had 4,000 joules of energy and it felt like pillow striking you at walking speed we wouldn't care. The bottom line is limiting injury. So I brought it up only to create a discussion on how these numbers may or may not affect the amount of damage to human tissue.
Some data for thought.
As we can see from these results, assuming the testing was done correctly, energy creep does exist and is quite significant. Although chronoing with .40s is not an end all answer because as is the case with the Gun 1, a gun can be tuned for a specific BB. With the Polarstar's seemingly infinite adjustability I would assume that you could achieve a result similar to Gun 1. I'm not saying it isn't a good idea to chrono with .40s, I'm just saying, as always, there's a workaround.
I would guess this energy disparity is probably giving p*s a significant advantage in terms of range on the field.
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Post by Stinger on Jun 25, 2014 10:49:00 GMT -5
I believe that whichever has the most inertia will cause the most pain, as it will impart the most energy upon impact due to its increased resistance to a change in momentum.
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