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Thread: Kinetic Energy

  1. #1
    AlienX
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    Default Kinetic Energy

    Well i was talkin with a friend he claims his new APA Mamba is around 100 K/E, Were do you go to get accurate K/E numers the sites I go to says we are both at 70+ K/E.
    Thanks for the help

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    Do you really care about kinetic energy? I know nothing in archery and bowhunting that is less important than kinetic energy although MANY manufacturers or archery shops will tell something different.

    Nobody dies because of a high kinetic energy. A higher Momentum is much more important. But that is something different..
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    Super Moderator bfisher's Avatar
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    I don't know why guys get all hepped up over kinetic energy. I see you are shooting 70#. Any bow 50# or more shooting a properly spined arrow produces enough kinetic energy to hunt almost anything in North America.

    People are still shooting animals the size of elk with 55# recurves, which produce half the kinetic energy of a comparable compound. I personally shoot setups that produce less than 40 ft/lbs of energy and blow right through deer sized game. It's all about shot placement and angles.

    Kinetic energy is a product of arrow speed and mass weight. Nothing more. Claims of 100 ft/lbs means a very haevy weight bow and an arrow moving fast. It doesn't have anything to do with being able to place all that energy into the vitals of an arrow. And it isn't a particular bow that does it. It's any bow that can shoot the same arrow at the same speed of an APA.

    Now, answering your question, try the ballistic calculators on www.bowjackson.com. Might be one on www.huntersfriend.com.
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  4. #4
    timtim146
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    You guys are right about that but more K.E is the difference of hitting bone and your arrow stopping or your arrow blowing through that bone :] But its not all about speed you can have a slower bow produce more k.e

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    No timtim, that is just wrong.

    Kinetic energy will not make your arrow travel further. It is the Momentum that is much more important for something like that. The Momentum describes the Amount of Velocity via the Energy that is transferred into your arrow, which will push the arrow through your target.

    The kinetic Energy of a gun might be really impressive. But the Momentum is very small.
    A Bullet will stop when it hits a body but the arrow will travel further.

    It is just about the perfect combination between a good bow and a perfect arrow that will give you the possibility to kill. The kinetic energy does not matter. A recurve bow does not have these amount of kinetic energy at all but you can easily kill with them. All you need is a setup that will fit to your needs.


    Just my 2 cents.
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    Quote Originally Posted by timtim146 View Post
    You guys are right about that but more K.E is the difference of hitting bone and your arrow stopping or your arrow blowing through that bone :] But its not all about speed you can have a slower bow produce more k.e
    I agree that KE is a factor to a point, and do not completely agree with a couple other statements made in replies, but not going to get into that.....the important thing is shot placement with well tuned arrow flight using a quality broadhead.

    To answer your KE question.......pretty simple to figure out.
    (Arrow weight in grains) x (FPS squared) / 450,240 = KE in ft-lbs

    So in the case of my Bengal:
    (464.9gr)(259fps)(259fps)/450240 = 69.265 ft/lbs of KE
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  7. #7
    AlienX
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    oops srry was just wondering cause my arrows go just as far into the target as his. Isnt K/E like the torque of a motor and speed is the same as Horse power.

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    Super Moderator bfisher's Avatar
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    Quote Originally Posted by AlienX View Post
    oops srry was just wondering cause my arrows go just as far into the target as his. Isnt K/E like the torque of a motor and speed is the same as Horse power.
    It might seem they are equal, but penetration into a target is not nearly the same as into or through an animal. If the arrow doesn't hit bone the arrow gets lubrication from blood and other body fluids which aids penetration. That's one reason arrows pass through as easily as they do.

    Penetration into foam or any other target is not the same. Such things as arrow diameter (surface area) and friction come into play here that become almost nonexistant passing through an animal's body.

    An arrow passing through a living body has other things too, such as muscle that gets flexed one way or another, depending on where the arrow hits. Then there is always the possibility of hitting bone. Hit heavy bone and all bets or scientific data go out the window.

    There are just too many posibilites to enter them all. I just like to say that just like bow poundage kinetic energy is nothing but a number and nothing to even worry about. As I said before, if you have a properly spined, good flying arrow with a good sharp broadhead shot from anything around 50# or more it'll get the job done if placed with accuracy. Poor shooting cannot be compensated for with a lot of unneeded kinetic energy.
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    Senior Member elkslayer4x5's Avatar
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    All I know for sure is that my 63# Slayer will be more than enough to take this brusier if I can catch up with him again.

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    Yep barry, all of that extra ke will bury your aarow deeper into the tree behind your deer after the pass through though. Some folks might find this useful
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