Kenetic energy
08-08-2003, 07:51 PM
#1
Spike
Thread Starter
Join Date: Apr 2003
Location:
Posts: 74
Kenetic energy
Has or does everyone figure there KE.I did the formula speed X speed X weight of arrow and divide by 450240.Came out to be 52.I' m shooting CXL 150 27" 60lb .Is that enough for a good pass through a white tail or should I go to a heavier shaft and sacrifice some speed.I know that everyone has different ops about it.would like some input Thanks for your time.
08-08-2003, 08:11 PM
#2
Join Date: Feb 2003
Location: CWD Central, WI.
Posts: 2,062
RE: Kenetic energy
52 ft. lbs. is plenty. You' d be pushing your luck if you shoot mechanicals, but a fixed blade should have no problems. If you like to play around with different shafts, weights and speed, heres a good site that will save you some math. http://home.att.net/~sajackson/archery.html
Mine runs between 79 and 83 depending on tip choice.[:-]
Mine runs between 79 and 83 depending on tip choice.[:-]
08-08-2003, 08:14 PM
#3
Giant Nontypical
Join Date: Feb 2003
Location: Dover, PA USA
Posts: 5,497
RE: Kenetic energy
Goldenarm.......
I ran some numbers and I' m not sure exactly what components you have on those arrows, but say a 27" CXL 150 at 27" with 4" vanes, nock and insert only weighs in at about 245grs without a point. (Lighter if you are using something smaller than a 4" vane) I can' t imagine they' d spine very nice with anything at or over 100grs for a head weight........which puts you under 350grs total finsihed arrow weight........no biggie with the right broadhead. My concern is the shaft selection. CXL 150s are VERRRRRRRRRRRRRYYYYYY fragile. Like pretzel stick fragile when it comes to any abuse. For that reason alone I would consider a different shaft.
To get a Ke level of 52# you have to be shooting this shaft in the 260fps range.
You could beef up a bit on the shaft......maybe like a CX-200 to give you just a bit more Umph and a MUCH tougher shaft.
Also keep your eyes firmly planted on the good cut on contact fixed blade style....they' ll compliment your set-up nicely.
If you want to play with some numbers for various shafts,weights etc. Go to www.bowjackson.com You' ll find all sorts of good calculators there to help you " See" an arrow before you buy or build it.
I ran some numbers and I' m not sure exactly what components you have on those arrows, but say a 27" CXL 150 at 27" with 4" vanes, nock and insert only weighs in at about 245grs without a point. (Lighter if you are using something smaller than a 4" vane) I can' t imagine they' d spine very nice with anything at or over 100grs for a head weight........which puts you under 350grs total finsihed arrow weight........no biggie with the right broadhead. My concern is the shaft selection. CXL 150s are VERRRRRRRRRRRRRYYYYYY fragile. Like pretzel stick fragile when it comes to any abuse. For that reason alone I would consider a different shaft.
To get a Ke level of 52# you have to be shooting this shaft in the 260fps range.
You could beef up a bit on the shaft......maybe like a CX-200 to give you just a bit more Umph and a MUCH tougher shaft.
Also keep your eyes firmly planted on the good cut on contact fixed blade style....they' ll compliment your set-up nicely.
If you want to play with some numbers for various shafts,weights etc. Go to www.bowjackson.com You' ll find all sorts of good calculators there to help you " See" an arrow before you buy or build it.
08-09-2003, 07:39 AM
#6
Boone & Crockett
Join Date: Oct 1998
Location: Hughesville, PA USA
Posts: 18,322
RE: Kenetic energy
Matt makes a very valid point. Also when it comes to KE, bows which are maxed out have a set amount of KE unless extreme variables are taken in arrow weight. The best way to increase KE out of a bow is to increase poundage. IF your bow is maxed out, one can usually tweak a bow and gain a few extra pounds without damage to the bow. This is done with twisting the cable(s)/string but make sure to check you tiller and cam(s) timing nock travel and tuning.
When you increase arrow weight with the same poundage, you decrease the speed of the arrow thusly in the formula, KE stays relatively the same. The opposite is true if you decrease arrow weight, you gain a little speed thusly retaining about the same KE. When extremes are taken in weight in either direction is when KE can be manipulated.
If you can tweak a few pounds and increase arrow weight, your KE should climb a little. It is recommended that one use 45 ftlbs of KE for whitetail sized animals and 55 ftlbs. of KE for elk sized animals tho in history, many animals have been taken with less. A good hit is the most important agenda for lower KE shooters and marginal shots are absolutely off limits.
Again, on Matt' s recommendation alone, you arrow shaft selection should be reconsidered.
When you increase arrow weight with the same poundage, you decrease the speed of the arrow thusly in the formula, KE stays relatively the same. The opposite is true if you decrease arrow weight, you gain a little speed thusly retaining about the same KE. When extremes are taken in weight in either direction is when KE can be manipulated.
If you can tweak a few pounds and increase arrow weight, your KE should climb a little. It is recommended that one use 45 ftlbs of KE for whitetail sized animals and 55 ftlbs. of KE for elk sized animals tho in history, many animals have been taken with less. A good hit is the most important agenda for lower KE shooters and marginal shots are absolutely off limits.
Again, on Matt' s recommendation alone, you arrow shaft selection should be reconsidered.
08-09-2003, 09:01 AM
#7
Join Date: Jul 2003
Location: Tulsa, Oklahoma
Posts: 1,051
RE: Kenetic energy
I was shooting a Hoyt Deviator when they first came out. I was shooting 31" 2512 shafts with 100 grain points and vanes, 30" draw, 67 lbs, and my speed was 285 fps. That translated into over 94 ft/lbs of KE. I' d hunting anything with that short of cape buffalo.
08-11-2003, 07:56 PM
#9
Join Date: Feb 2003
Location: Port Hope Ontario Canada
Posts: 35
RE: Kenetic energy
I shoot a hoyt magnatec 70# with a 27 1/2 inch draw 28 inch 2315. 125 grain tip 547 grains total weight, on a scale. It comes off my bow at 231 f/s through a crono. My bow is at it' s max weight. Though paper it just leaves the three cuts from the fletchings right off the bow and at about 12 feet.
