Why do fields have lower FPS/Joule limits for HPA vs an AEG.

Discussion in 'General Airsoft Discussion' started by Peeque, Jun 17, 2021.

  1. Peeque

    Peeque Well-Known Member Supporting Member

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    I thought it was just the people running one of my local fields finding more ways to be stupid. I just saw a post on reddit mention an even bigger difference in Joule limits at their local field. Now I'm wondering if there's a legitimate reason for it.

    One of my local fields has a 1.64J / 420FPS limit for AEG's and 1.52J / 404FPS for HPA & Gas guns. The other field is just 1.48J / 400FPS. Doesn't matter how it works.

    1.64J is 1.64J is it not? It shouldn't matter what system is behind it.

    Is there a legitimate reason for this or is it just an irrational fear of HPA? Or maybe there's more to it that I don't understand.
     
  2. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    It's HS Physics! And as one of my statements, real life system is not that simplistic. Video game gun stats does not apply.

    With Gas/HPA gun you can massively joule creep. Take a .20 and a wide/large bore, with a big pressure wave it will poop out the bb at a low Joule due to the Law of Inertia.

    Put a heavier bb in the same system and time in the barrel is much longer. Thus when it finally leaves, it will be at a higher Joule.

    https://www.physicsclassroom.com/class/newtlaws/Lesson-1/Newton-s-First-Law
     

  3. Peeque

    Peeque Well-Known Member Supporting Member

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    I know of Joule creep. That's why everyone chronos with the fields own .36g BB's. That way if your setup would take advantage of JC it would be "detected". And regulator locks are required so you can't turn up the pressure later.

    I guess with HPA you could still cheat it by using an even wider barrel and higher pressure to get the same effect with .36g.
     
  4. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    In theory...yes.
     
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  5. GrimWolf0770

    GrimWolf0770 Active Member

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    I hate psychics.......X~X
     
  6. Peeque

    Peeque Well-Known Member Supporting Member

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    So when a fields Chrono process prevents people from abusing Joule creep in the first place, enforcing a lower limit for HPA/Gas users is pointless, isn't it?
     
  7. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    That depends...but if a field did chrono with .36...yes.

    But, most don't.
     
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  8. richman992

    richman992 Well-Known Member

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    If I’m understanding this right, wouldn’t this also mean that regular GBB guns should be subject to the same restrictions? I don’t run HPA but I’ve noticed local fields having separate restrictions for HPA and didn’t understand why.
     
  9. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    Long guns, should be...pistol...not an issue due to the short barrel.

    Of which I can say...I have exploited that rule. I ran a G35 with a 7" barrel and my pistol shot as hard as an AEG with a M110 spring in it. - .20 at 375fps.
     
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  10. Peeque

    Peeque Well-Known Member Supporting Member

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    What if they don't Chrono with heavy BB's and Chrono everyone with .20g like most fields probably do. At the same time they limit HPA/Gas to 1J and 1.5J for AEG. Like the guys field I mentioned in the first post.

    That would allow HPA and AEG users to take advantage of Joule creep to pass Chrono and then switch to heavy weight BB's afterwards where they then shoot over the limit.

    So what does limiting HPA to 1J do in that situation? Do they assume the HPA users will do this and when they Chrono in at 1J with .20g then switch to something heavier during the game they still end up within the 1.5J limit?

    Surely, there's a limit to how much creep you can get, even with HPA, but it's probably more than .5J. Or maybe it isn't and that's why they do it?

    I can't think of a scenerio where limiting HPA/Gas to less than the AEG limit actually "works". Instead of chronoing everyone with heavy BB's to "detect" Joule creep that goes over the limit. It just seems like a shitty solution that doesn't solve anything. And puts the people who don't abuse it at an unfair advantage to those with an AEG. Maybe, I still don't understand it.
     
    Last edited: Jun 17, 2021
  11. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    That is the goal, restrict their J output al lower levers and JC will be minimal due to the lower pressure levels.

    No an AEG has far less JC potential than a HPA gun.

    Since you can't determine the acceleration factor, you will need to run live experiments to see the numbers.

    Run some numbers with an over volumed AEG and a HPA Airsoft gun with a wide bore. You will see the variances once you do.
     
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  12. Peeque

    Peeque Well-Known Member Supporting Member

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    How wide is wide? ORGA 6.23 wide or 6.05 wide?
     
  13. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    6.05mm is not Wide. That is considered Tightbore.

    Standard Bore is 6.08mm, this maintains the .08mm ideal for in the 1990's bbs were more true to 6mm than today. It was determined by TM that you should maintain a bore variance of .08mm to allow for a good air cushion to form around the bb.

    Wide bore starts at 6.10mm, ie wider than stock and run up to 6.23 in an orga.
     
    Last edited: Jun 17, 2021
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  14. 1tonne

    1tonne Well-Known Member

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    No matter what the gun, people should be chronoing with the bb weight that they are playing with and also the hopup set to fly straight.
    All guns can JC. I did an experiment once to see how much I could joule creep an AEG. The 0.2gm bb's were shooting 350fps (1.13joules) but the 0.45gm bb's shot at 1.75 joules. So a big jump their.
    I never gamed with the gun
     
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  15. sheed

    sheed New Member

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    I've seen this same conversation on a few Airsoft Community sites. Personally, I don't understand why joules hasn't become the airsoft standard measurement. It prevents HPA player from being labelled the "cheaters" and stops the BASR guys from exploiting JC to get to unsafe power levels.
     
  16. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    Because it all rolls back to the lack of being any Standards in this industry. The FPS by bb weight is a hold over from the early 2000's when Airsoft insurance was picked up by the APL, which adopted the "industry" guideline at the time of FPS with .20g.

    It had no statement for measurement via joules back then and there is nothing mandating that it be standardized now.
     
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