BobCo19-65

I have heard so much talk about how KE is the main component for penetration. Lets talk about that. Is KE really the only component that makes up penetration? Will a field point of equal weight penetrate as well as a broadhead shot out of the same bow? They both have the same KE. Of course not. And I'd like to talk what other factors make up penetration.

Edited by - BobCo19-65 on 08/14/2002 08:25:57

FLHunter

Bob,

KE is a value of the amount of energy the arrow is carrying out of the bow. That value deminishes as the arrow goes down range as the energy of the shot bleeds off and the arrow slows. I don't agree that a field point won't penetrate as well on the same arrow because it has less drag than when the broadhead is attached. There are a number of considerations that will effect penetration, here are some:

1. Broadhead design, ie. cut to the tip vs. a chisel point.
2. Cutting diameter of the broadhead, more diameter more drag.
3. The diameter of the arrowshaft, smaller shafts penetrate better due to less drag.
4. The weight of the arrow, a heavier arrow carries more KE.
5. The velocity of the arrow (important factor in the KE equation).
6. Shot placement on the animal.
7. The sharpness of the blades of the broadhead.


Aim Hard!



Edited by - FLHunter on 08/14/2002 08:32:41

Slo-bo

Good question, BobCo, I was just talking about this with a friend this past weekend. I had a number of different arrows of different weights and speeds, all with field tips, and shot them all several times into several different target mediums, in unshot areas of the targets. Not any kind of scientific test, obviously, but I was curious how speed and weight factored into penetration. I assumed that the arrows that had the most KE, according to the charts, would have the deepest penetration. I found in fact, that the lightest, fastest arrows penetrated evenly, or sometimes a bit deeper than the heavier arrows. Now granted, there wasn't a huge difference in calculated KE, but enough that I assumed there would be more of a difference. I also realize that shooting into a dense target is different than shooting into a live animal, and that there are factors such as larger arrow diameter equaling more drag in the target,(this is just an assumption on my part, I shouldn't be surprised if I'm corrected on this!), and of course, actual penetration in/through an animal will rely heavily on the type and sharpness of the broadhead used. In my opinion, in most cases, once you have reached a certain speed/KE, it becomes somewhat of a mute point, it's more a matter of how deep in the ground the arrow will stick on the other side of a pass-through shot.
As far as factors in actual penetration, much will affect this. A perfectly tuned bow, with the correctly spined arrow, and a super sharp head, would certainly give better penetration than a poor set up. If I remember correctly, you shoot traditional also,(or exclusively?), so I would be interested in knowing about KE=ing penetration in slower arrows. I look forward to the replies from this post, good one!

amosgreg

Target mediums come, in some cases, close to simulating an animal and in others don't even come close.
As FLHunter described KE is a unit of measurement and penitration a different measurement. Can 1 be used to describe to other? It serves as a guideline but just plugging in the information into a formula isn't going to work in my humble opinion.

The bottom line is what are you going to be hunting?
Does to bow have enough draw weight(standard by most states, 40 pounds for Deer in Ohio) to launch an arrow and broadhead(types and minimum broadhead designs are also governed by most states 3/4 inch in Ohio) to cleanly kill game animal X?

The numbers serve a point but keep in mind the shot is what counts.
Does a recurve at 40 pounds shooting a 3/4 inch broadhead at about 160-180 feet per secound develop enough KE to kill a Deer? The state of Ohio says so. Is it enough for most folks?

I am a firm believer that the shot is the most important thing and if your equiptment is set-up and tuned to group your hunting broadheads, You make a quality shot, The Deer will be a trophy for you. End of Story!
You have a good set-up and hit the point of the shoulder blade, the arrow bounces out, 5 inches back and complete pass through. Do I have enough KE?
IF my only experiance was the first shot the obvious answer is No I Don't!


There are a number of guys who believe the numbers above everything else, and to them I say Good Luck this year. Me I have a hunting set-up and it works.

Greg

"Getting close to the game is the joy of Bowhunting for me, the harvest is a bonus."

Live 15 ft Python after eating a small Antelope!

BobCo19-65

amosgreg, I understand what you are saying about shot placement, and if you ask me what is more important, shot placement or KE, I would undoubtedly say shot placement.

I guess the point of my topic is that I have been hearing so much about KE lately as it pertains to penetration, and I think that people are getting a little off track in believing the PE = penetration. What I'd like to hear are the other factors that pertain to pentetration. I don't think that you could say that KE does not apply to it because speed and weight are factors in penetration IMO, but there are many other factors.

Slo-Bo, yes, I do shoot traditional and it is my passion, I also shoot compound. I shoot a 58 pound recurve with 700 grain arrows, 31.5 draw. So, I'm putting out about 50 pounds of KE. I also use 145 grain Stos (made by magnus) two bladed cut on contact heads (I use the same heads for both trad and compound). With my trad setup, I will only shoot at deer up to 20 yards, with the compound, 30 yards max. Is penetration a problem in traditional, no. But, as amosgreg has stated, shot placement is.

Edited by - BobCo19-65 on 08/14/2002 09:36:54

pdq 5oh

I would think a heavy arrow, with the same KE, would penetrate better than the lighter arrow, by virtue of mass weight. At the same energy levels it takes more resistance to stop a heavy projectile than a light one. At some point there are trade-offs. Shot from the same bow a lighter arrow may perform better than a heavy one, especially at lighter draw weight. Running the numbers there comes a point where an optimum arrow weight is realized. Many things need to be considered. Shaft weight, length, and broadhead weight, to arrive at a good compromise of total weight and FOC. For my setup a 375 gr arrow (100 gr head) seems to work best, giving a good blend of FOC, KE, speed, and trajectory. Not to mention shooting and grouping well. As others have stated a well tuned bow is highly important to good penetration. An arrow darting and dodging all over the place is not going to penetrate very well, IMO.

Phil.

WV Hunter

I have to agree with phil. IMO the heavier arrow "should" penetrate better. However like FL said...there are alot of factors involved. I've killed deer with complete pass throughs from bows ranging from 53lbs to 69lbs of KE. In fact, very few out of a few dozen have not been a pass through. So I also have to agree with Slo-bo's statement...
" In my opinion, in most cases, once you have reached a certain speed/KE, it becomes somewhat of a mute point, it's more a matter of how deep in the ground the arrow will stick on the other side of a pass-through shot",
with this addition..."with a sharp, quality, broadhead".

One theory I've always had, and whether or not it is any good(LOL), is that if you have adequate KE, on a shot into a live animal, the shaft size really doesn't mattter...you have a 1"+ broadhead making a hole through that animal...the shaft just follows the head through the hole...it doesn't really act like a target and slow down by friction. (Of course...if you dead center the shoulder then it would obviously be different than a behind the shoulder all flesh hit.) But you get my point.
Penetration...IMO is based on KE, but ALSO on broadhead performance...if you have a good head, that can drive through flesh and bone, (even on a bad hit), you will get good penetration. In fact, I think even if you have marginal KE with a really good head, you will probably equal or outperform a setup with alot of KE, and a poor head. I've been shooting Magnus 2 blade 125's and have had some incredible penetration out of my last couple bows, and none of them is a speed demon by any means(240 at max). I personally believe it is because of the head. I think alot of traditional archers realize the way these type of heads work, and that is why they use them. Even with low KE, you can still have great success. That is my humble opinion, and maybe I'm nuts...but it works for me <img src=icon_smile_big.gif border=0 align=middle>

amosgreg

Good points WV Hunter,
Question: How much draw weight did an Indian have on their bows back in the late 1700's/early 1800's?
How did this affect the flint broadheads they shot?
Not intent on starting a flame war just a thought concerning this issue. Has anyone done any studying(that anyone knows about) as to the effective draw weight of some of these selfbows and the weight of the arrows it shot?

That would be some interesting reading!

Greg

&quot;Getting close to the game is the joy of Bowhunting for me, the harvest is a bonus.&quot;

Live 15 ft Python after eating a small Antelope!

BobCo19-65

WVhunter, good post but one question:

<BLOCKQUOTE id=quote<font size=1 face='Verdana, Arial, Helvetica' id=quote>quote:<hr height=1 noshade id=quote> Penetration...IMO is based on KE, but ALSO on broadhead performance...<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face='Verdana, Arial, Helvetica' size=2 id=quote>


Let me ask you this question then (same braddhead scenio), An arrow hits a deer in it accelerating stage of flight, lets say with 45 pounds of KE at five yards. Another arrow shot out of exactly the same bow with exactly the same arrow hits a deer in exactly the same spot in the decelerating stage of flight at lets say 40 yards with the exect KE of 45 pounds of KE. Which arrow will have the better penetration potential? Or will they be the same? Since they both shot out of the same bow, have the same speed, same broadheads, and same arrow weight.

Edited by - BobCo19-65 on 08/14/2002 11:30:11

WV Hunter

BobCo...good question. Honestly...I'm not sure which would do better. If I had to guess, I would have to say the one at 5 yards would probably win out, since it is still accelerating(if in fact it was still), and is probably going straight(er) upon impact than the longer shot would be. But if you look at it by the numbers...that would tell you that they should be the same. The numbers probably aren't always right, there's too many other factors involved in penetration other than just KE.
What do you think?