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Thread: arrow speed calculator

  1. #1
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    arrow speed calculator

    here is a site that has an arrow speed and kinetic energy calculator.

    so add up what you have in grains added to your bare string (peep, loop, kiser, etc..)
    put your weight in grains for the arrow you shoot.
    slide the bars in the bows advertised IBO,
    draw length you shoot and actual pounds you are pulling

    http://backcountrybowhunting.com/articles/calc/



  2. #2
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  3. #3
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    I used it and checked with a chrono at my shop and was within 2 FPS

    Mike

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    Quote Originally Posted by donheater View Post
    I used it and checked with a chrono at my shop and was within 2 FPS

    Mike
    Thats the same answer I have gotten from several guys thats shot through good chronos.
    I have used that calculator many times and found it to be quite a bit different than my chrono though. Between a friend and myself we both believe my chrono indicates slow.
    Others that have the Pro Chrono agrees, they indicate slow.
    I cut my arrows twice and they're still too short.

    Every time you win an argument on Archerytalk you still lose because invetibly you're gonna tick off someone else.

  5. #5
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    Quote Originally Posted by Skeeter 58 View Post
    Thats the same answer I have gotten from several guys thats shot through good chronos.
    I have used that calculator many times and found it to be quite a bit different than my chrono though. Between a friend and myself we both believe my chrono indicates slow.
    Others that have the Pro Chrono agrees, they indicate slow.
    What the heck, just add 25 FPS to whatever your chrono says, I think it's done here ALOT
    Quote Originally Posted by ChappyHOYT View Post
    Hunting shows have turned a once proud part of our heritage into a contest of inches. No wonder society sees hunting more and more in a negative light.

  6. #6
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    Quote Originally Posted by huntin_addict View Post
    What the heck, just add 25 FPS to whatever your chrono says, I think it's done here ALOT
    Yeah no doubt.
    I do find my chrono consistant enough to use it for tuning purposes so its not a complete waste.
    Thinking I'm gonna see if I can get it recalibrated soon.
    I cut my arrows twice and they're still too short.

    Every time you win an argument on Archerytalk you still lose because invetibly you're gonna tick off someone else.

  7. #7
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    The distance you are from the chrono matters too. for consistancy stay at least 1 arrow length away or even 2 arrow lengths away from the chrono, but keep it consistant.
    If you push right up against it you will get variations. But you can also do testing on drop aways vs whisker biscuit vs spring steel lizard tongues, etc...
    Also that 2 fps could be weight difference from serving, or you may be a 1/2 pound off on pull weight, lot of variations.

  8. #8
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    I love that sight and calculator; very accurate for me!
    "His arrow will flash like lightning." Zechariah 9:14
    Hoyt Carbon Spyder 30, CBE Tek Hybrid sight, QAD Ultra Rest HDX, Injexion Arrows & Blazers, QAD Exodus broadheads, TightSpot quiver, Stokerized SS1 stabilizer, Spot Hogg Wiseguy release, Zeiss Conquest HD binocs, Leica 1000R rangefinder, Kifaru Timberline 2 pack, Bark River Gunny Hunter blade, Kuiu clothing, Lowa Cevedale boots

  9. #9
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    Quote Originally Posted by huntin_addict View Post
    What the heck, just add 25 FPS to whatever your chrono says, I think it's done here ALOT
    Ain't that the truth. Then they get mad at you when you say something.
    " Life's tough... It's even tougher if you're stupid" - John Wayne
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  10. #10
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    I have a post on here somewhere where I laid out how to calculate your arrow speed from rated IBO, but it has gotten buried in amongst my many other posts. I will rehash it here.

    1. Subtract 2.4 fps for each lb of draw weight change below 70#, add 2.4 fps if going above 70#
    2. Subtract 10 fps for each 1" change in draw length from 30.25"(I have found in testing that they are actually using this as the IBO draw length), add 10 fps if going longer than 30.25"
    3. Subtract 0.4 fps for each grain change heavier than 350 grains, add 0.4 fps if going lighter than 350 grains
    4. Subtract 0.3 fps for each grain added to the string(loop, peep and/or kisser(speed nocks/silencers had little effect on speed calculation below a total of 40 grains(only cahnged 0.1 fps for every 10 grains))

    Using this calculation, I am typically within +/- 3 to 5 fps of the chrono'd speed
    2009 PSE Xforce GX 60#/27 1/2"(283 fps w/366 grain arrow)
    2011 PSE Omen Pro 60#/27 1/2"(298 fps w/382 grain arrow)
    2011 PSE Bow Madness XL 55#/27 1/2"(258 fps w/386 grain arrow)
    2011 PSE Axe-6 58#/27 1/2"(IBO)(298 fps w/300 grain arrow), 55#(ASA)/27 1/2"(287 fps w/305 grain arrow)

  11. #11
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    ok to answer a pm to everyone as to why put some distance between you and the chrono.
    Well believe it or not a shockwave from the bow will effect the accuracy of the chrono. Although the shockwave is minor compared to a gun blast, there still is a small amount, that's the minor harmonics you don't feel in your hand. That's why on guns they give you chrono data at 10 to 15 feet depending on caliber.
    There is some slow motion video to back this up, but generally if your about an arrows length away the shockwave dissipates (sp) enough to below the threshold of the chrono's ability to detect and gives you a more accurate reading. This also depends on the brand of chrono used.
    If you shoot target style bows with long stabilizers, just get a foot or so away from the end of the stabilizer.
    hope that helps

  12. #12
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    was within 1-2 fps for me too

  13. #13
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    Quote Originally Posted by gridman View Post
    was within 1-2 fps for me too
    That seems to be the norm. With all my testing and figuring, it shows my chrono being slow by 15 fps. I just wish I knew someone that has a good, accurate chrono to shoot side by side of mine as a comparison.
    I cut my arrows twice and they're still too short.

    Every time you win an argument on Archerytalk you still lose because invetibly you're gonna tick off someone else.

  14. #14
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    I have a prochrono and i have been happy with it. My chrono reads 6fps slower than what the calculator says. I am happy with that for now, but I need to learn to leave well enough alone.

    Romey
    US Air Force Retired

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