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Thread: hmmm interesting about kinetic energy

  1. #1
    Member ruvimarrow's Avatar
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    Default hmmm interesting about kinetic energy

    I was reading one of Bernie Pellerite books today (IDIOT PROOF ARCHERY)and he's saying its not the energy that results in penetration, its the efficient use of energy that does. One of his examples was two difrent arrows shot from same 60 lb. bow one was 307 grain carbon flying 282 fps.and the other was 567 grain aluminem arrow flying 218fps.
    567 arrow 60 lbs kenetic energy one foot behind chrono
    307arrow 54 lbs kenetic energy one foot behind chrono
    same test now but taking measurement 20 yards from chrono=
    307 arrow 50.5 lb
    567 arrow 52 lb
    again same test at 29 yards both arrows produced nearly same amount of kenetic energy307 =269 f.p.s. 49.34 foot pounds and the567 grain arrow at 198 f.p.s.=49.36 foot pounds
    so at 30 yards the light arrow would actualy carry more energy!

  2. #2
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    Default

    Ahhh yes grasshopper, but don't forget our old friend momentum.....

    And things like weight forward, etc.
    Vance in AK.

    Matthew 6:33
    "But seek first the kingdom of God and His righteousness, and all these things shall be added to you."

  3. #3

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    Interesting numbers. As much as opinion and personal preference plays into archery, it sure is nice when something that's entirely driven by physics. Other factors that come into play that reduce arrow speed as range increases, such as drag, all play into the equation at some point. But, all these factors are properties of physics and can be quantified. Of course I'm not advocating poor shot selection just because your bow has high kinetic energy at a given range. There are "non physical" properties, such as human logic, that dictate whether an animal is harvested cleanly.


    I sometimes wish I had a chrono of my own and could play around with different numbers comparing my Mathews to my stickbows.

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    Moderator Daveinthebush's Avatar
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    Default Good book

    That is a good book.

    Grand old argument. I think for archers it is best to be in the middle, esp. if you are a compound shooter. Too light is harmful to your equipment and noisy. Too heavy and you loose trajectory. I am somewhere in the middle, around 525 to 600 grains depending on what I am hunting.

    Vietnam - June 70 - Feb. 72
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    Member ruvimarrow's Avatar
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    Default my 375 grain arrow probably to light?

    I think i will probably need to make my arrow a little heaveir i shoot a bowtech tomcat set at 68 lbs, 281/2 draw length. using a short overdraw i shoot 26 inch cabelas hunter arrows tipped with 100 grain Wac em triton BH = total weight 375

    Which is perfectly safe and quiet with the sts system on the bow,which all comes to 285 f.p.s.
    I will probably buy 125 grain BH next time and cut my arrows at about 28-30 inches instead of 26 inches. What would you guys advice? thanks

  6. #6
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    I shoot a bowteh tribute set at 62 pounds and cx maxima hunter 350 cut to 28in. and shoot a montech 125grain head and it all weights in at 393.6 which I think is perfect for the bow

  7. #7

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    Quote Originally Posted by ruvimarrow View Post
    I think i will probably need to make my arrow a little heaveir i shoot a bowtech tomcat set at 68 lbs, 281/2 draw length. using a short overdraw i shoot 26 inch cabelas hunter arrows tipped with 100 grain Wac em triton BH = total weight 375

    Which is perfectly safe and quiet with the sts system on the bow,which all comes to 285 f.p.s.
    I will probably buy 125 grain BH next time and cut my arrows at about 28-30 inches instead of 26 inches. What would you guys advice? thanks
    What are you hunting?


    Your rig sounds like very good medicine for just about anything. Your 100g BH cuts a nice 1 1/4" hole just like the 125, and you have more than enough kinetic energy to pass thru a bison, moose, or grizzly.

    Rigs with a lot less behind them than yours (Fred Bear's) have been shot thru the ham and exited the moose's neck.

    That being said, I like heavier arrows when it comes to cuttin ribs.

    How high can you crank up and use your bow?

    You may be able to get a heavier arrow and more speed with 10 more lbs of draw weight, if you want to go there.
    Or a bigger head with a bigger diameter cut and still maintain decent WFOC with a slightly stiffer, heavier shaft and overdraw.



    I'm lucky enough to be able to pull heavy bows, but it's not for everyone. Especially when it's cold.
    Personally, high draw weight and a heavy arrow gives me confidence that I'm deadly.

    But if you really want to pass through anything that walks with barely a wisper, use a 2-blade head. Daggers cut easier than pyramids.




    Sorry, couldn't resist...hehe

    Ishkababble...

  8. #8
    Member ruvimarrow's Avatar
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    Default oops

    oops i just checked the weigt of my arrow again and it was actually only 343.7 sorry my bad.
    I plan on using it mostly on caribou and black bears. but might go for moose thus the reason for a littal heavier arrow.
    When i bought my bow at sportsman they seid it was a 70 lb. bow but when i brought it home and cranked it all the way it was only 68 not that bad but would rather shoot more.
    Is their very many bows out there that shoot over 70 with out having to speical order? any body know?

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    Moderator Daveinthebush's Avatar
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    Default Haven't seen any.

    I have not seen any bows listed that are over 70 lbs. Someone on one of the other forums was looking for a 90-100 pound bow. I shoot 70 and it is more than adequate for anything up here. Only once, of all the animals I have shot in AK, have I not had a complete pass through. And that shot is still a mystery to to me.

    Vietnam - June 70 - Feb. 72
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  10. #10
    Member Matt M's Avatar
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    Default K.E.

    The question is do you need to change what works. Some of us like speed as a flatter shooting arrow or bullet can compensate for being off on your distance. Shorter arrow flight time can give you a better chance of delivering the goods and reducing the chance of an animal taking that extra step turning a good shot into a bad one.

    I wouldn't want a feather light arrow pushing a broad head nor would I want a cannon ball pushing one either.

    Most bows of the last few years are more than adequate in power stored and delivered energy for ALL game in North America at 60 lbs. Now I am on my soapbox! All you bowhunters, save your shoulders and shoot what is comfortable for you. Do you want to be turning 40 or 50 and have to give up archery because your shoulders are shot? Let me know as I can give you a great referral to an orthopedic surgeon!

    You do not have to keep up with the Joneses as far as poundage but you do need to be the Jones when it comes to accuracy on skills in the field.

    Cheers,

    Matt

  11. #11

    Default Weight Paradox

    Yes, Dave and Matt are right. No need to shoot a heavy bow to kill game.

    No need to change a deadly setup either, unless you enjoy tinkering.




    But I have to make fewer compromises. I like that.

  12. #12
    Member ruvimarrow's Avatar
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    Default confesion

    alright,alright, I admit to injoy tinkering with my bow and the 42- weather ain't hellping
    my bow is bigining to weigh a lot

  13. #13

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    I shoot a 28" gold tip XT hunter with my old Fred bear bow set at 72lbs pull. I use an over draw and my draw length it 31 1/2". I also use the 125 grain montecs.

    I figure my arrow with the broadhead is close to 375 grains. Arrow speed is 285-300 FPS.

    What this arrow does and how these broadheads hold up amazes me. I have taken 3 caribou and one black bear with this set up.

    Just a quick run down on the performance. 1st ever bow kill was a Caribou on the hall road. It was the last day of a 10 day hunt, finally a caribou withing 90 yards (he was 68 yards), I felt confident out to 75-80. Caribou was trotting left to right, i let my arrow fly, made a bad shot and hit him just below the hip on his back leg. The arrow and MOTEC broke his femur clean through at 68 yards, i agree that is was not the most ethical shot. How ever I did manage to get a second arrow in him and he was down. The braod head could have been touch up and re-shot no problem

    2nd BOU was 35 yards with perfect pass through, double lung and bottom of the heart. He ran 15 yards tops, this arrow could have been picked up and re-used as is (i did not use though).

    3rd Bou was 12 yards, facing hard quarter away, arrow hit him on the outside of the back leg, just under the skin, arrow carried all the way through his chest, hitting bottom of the heart and some lung, broad head punched throught the ribs in the front and was sticking out about 6-8 inches. Again Bou made it about 15 yards.

    1st blackie, 5' boar, was climbing the tree I was in. I struck him in the soft spot of the neck between the collar bone- rib cage (little V area) he was only about 6 feet away, the arrow and Montec carried all the way through his body and exited right next to his right knee cap. Hitting vitals on the way through, the arrow made a complete pass through before he was able to jump from the tree, he ran 20 yards tops.

    So thats my story and I highly recomend the 125 grain montec G5's. I swear by them and will not change ever.

  14. #14
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    Default Ballistic Co-efficient

    Without knowing more about the orginal post quoting results from an arrow flight test, I'd have to say the aluminum shaft had larger, less wind resistant fletching. Normally, a heavier object retains it's velocity better than a light one.
    Dave Holt had an article in Bowhunter magazine 15-20 years ago regarding arrow effiency at different weights and velocities. His findings contradict the author's results mentioned in the original post.
    Daveinthebush has it right. Not too light, not to heavy. Usually 450 - 500 gr. is good for anything, especially when tipped with a razor sharp two blade. Modern compounds easily produce enough KE to shoot darn near any arrow - BH combo.

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