Are faster bows wounding more deer?

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Re: Are faster bows wounding more deer?

Unread postby Dhurtubise » Mon Jul 01, 2013 3:49 am

DEERSLAYER wrote:I think your making assumptions that all other things remain static. Your not taking into consideration how big of a drop in the arrow speed is affecting the numbers you are putting into that formula or the fact that bows transfer energy to a heavy arrow more efficiently than a lighter one. It's easy to change speed. Just buy a different bow.


I am aware that the velocity of the arrow will drop with increasing the weight. That goes without saying.

But the KE transferred to the arrow has to be a direct Function of the potential energy stored at full draw. There should be very little difference in the KE value of a heavy arrow compared with a light arrow as a result. The next post down has some results that clearly indicate that in fact the energy transfer is a little bit more efficient with heavier arrow.

Follow this logic for a moment. Two arrows leave the same bow with the same KE. One Is it lighter and faster, the other heavier and slower. Since their velocities were squared to obtain that KE

E = 1/2mv2

It follows from the momentum function where the velocity is to the power of one only to obtain a value,

P = mv

That momentum will forcefully be greater in the heavier arrow with the same KE but slower trajectory.

If what you want is an increased chance for pass through, then this can be achieved simply by selecting a heavier arrow for the same bow (and saving your $, unless of course you want a new "shiny" bow, which is another consideration altogether).

On the other hand a faster bow will obviously produce grater momentum in the same arrow, but how much. When you read the literature on a bow, they use the KE value to quantify their bows. It makes sense because this value should be relatively consistent regardless of your choice of arrow weight. However I think that overall this value is misunderstood, and at least a little misleading for your average hunter. Looking at the values from your other post, comparing a 70 lb bow shooting a 500gr arrow at 280fps with 87ftlbs energy, with a 60 lb bow shooting the same arrow at 260fps with 75ftlbs energy. That 20 ftps more provides an extra 12ftlbs energy, or 12/75 = 16% more. But from a momentum perspective, given the linear relationship with velocity, 20/260 = 7.7% more. That is how much more your increase in pass through potential you gained by increasing the limbs on that bow from 60 to 70 lbs. It isn't insignificant, but it is far from substantial.



DEERSLAYER wrote:Have you ever heard of Norb Mullaney?


No. Should I have? Who is he.

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Re: Are faster bows wounding more deer?

Unread postby DEERSLAYER » Mon Jul 01, 2013 6:53 am

I think I understand what your saying, but I'm not 100% sure. I thought we were strictly talking about the KE a bow produces with a heavy (slower) vs a light (faster) arrow and not momentum. That is what I was trying to show with my previous example showing that the heavier slower arrow had more KE out of the same setup. I believe the KE referenced in standard literature is based on the IBO rating. It would change if they used a different set of circumstances such as a heavier arrow as used to be done using the old AMO rating.

Norb Mullaney was a highly respected engineer that did independent bow testing for about three decades. He retired several years ago, but his work is still well respected. He was considered "the" man when it came to testing and determining things like we are talking about. He combined real world test results with theory to show what a particular bow was capable of and how making changes to arrow weight affected speed and kinetic energy. He mainly published bow reports, but he also wrote some general articles on the subject. He is sort of the grandfather of bow testing.

Here is a quote that I think applies and is a view that is shared by many in the world of archery.
http://www.grandviewoutdoors.com/bow-reports
"This archive of award-winning Bowhunting World Bow Reports written by the most-respected Bow Test guru on the planet—Archery Hall-of-Famer Norb Mullaney—is ready to help."
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Re: Are faster bows wounding more deer?

Unread postby DEERSLAYER » Mon Jul 01, 2013 7:18 am

goldtip5575 wrote:I wonder how many fps you lose when you put in a draw length of 26-28 a more realistic example of most archers...

I don't remember how much difference it makes, but the draw length can affect the speed and energy quite a bit.

goldtip5575 wrote:...Also is it really that much of a difference between 84.31 and 87.06 to lose speed.

Not in my mind. When your looking at those type of numbers I don't think it's a big deal unless your hunting large dangerous game where you want every ounce of energy you can get, but with very low poundage bows that are on the boarder of being too weak I think the resulting difference could be important. Although my point wasn't really about the difference, it was about how a slower arrow (resulting from the heavier arrow) out of the same bow had greater KE. Not the faster (and thus lighter) arrow.
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Re: Are faster bows wounding more deer?

Unread postby Schultzy » Mon Jul 01, 2013 7:56 am

You bet they are! Though It's not the bows fault but rather the so called "pro techs" at these archery shops telling every bow hunter In there that bows are much faster now so you can take longer shots. Then you add to the fact the crap you see on TV of these Idiots taking long bomb shots at deer, elk, you name It. These people at the these pro shops and hunters on TV are gods to people so obviously their going to try and emulate them. In all honesty I hate what bow hunting has become.

As far as heavy arrows vs light arrows- us traditional bow hunters have proved that point time and time again. Unfortunately speed sells now In the archery Industry rather then efficiency. A person can have both with today's compounds. When my body tells me my recurve days are over I'll go back to a compound with a heavy arrow and add the speed of these compounds of today to that and my arrow/bow combo Is going to be outstanding!! I don't understand why more won't do It. I kid. I know why, the speed thing. ;)
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Re: Are faster bows wounding more deer?

Unread postby Dhurtubise » Mon Jul 01, 2013 8:08 am

DEERSLAYER wrote:I think I understand what your saying, but I'm not 100% sure. I thought we were strictly talking about the KE a bow produces with a heavy (slower) vs a light (faster) arrow and not momentum. That is what I was trying to show with my previous example showing that the heavier slower arrow had more KE out of the same setup. I believe the KE referenced in standard literature is based on the IBO rating. It would change if they used a different set of circumstances such as a heavier arrow as used to be done using the old AMO rating.


Your data showed indeed that the heavier, slower arrow had more KE. It also gave enough info to compare values between stronger and weaker bows for KE and infer momentum properties. Thanks.

It's just that the original article referenced in the first post focuses on momentum as a measure/indicator of potential pass through as opposed to KE. The article stipulates (rightly) that a slower heavier arrow out of the same bow will have greater momentum to counteract the resistance of the animal's tissues against the arrow tip moving forward and through the body.

I think also that KE is a useful, if not necessary measure of a bow's ability to transfer the potential energy stored at at full draw to the arrow. This is mainly due to kinetic energy being relatively constant over the range of expected arrow weights (even though a small increase in energy transfer efficiency is observed with increased arrow wt, we are talking in the order of 5% according to the data you shared).

It is important for the hunter not get too focused on the individual KE values reported by the bow manufacturer by relating it to the bow's ultimate capacity to kill an animal. That's because a slight increase in speeds will effect a more substantial increase in the KE value, but the real measure of the bow's effectiveness, momentum will only increase slightly. To get back to your previous example, the 70Lb limbs providing 87ftlbs of KE sounds a lot better/stronger/sexier than the 60lb limbs with 75ftlbs, when in actuality the bow only provides 7.7% increase in the bows ability to pass through an animal's body.


[/quote]

Norb Mullaney was a highly respected engineer that did independent bow testing for about three decades. He retired several years ago, but his work is still well respected. He was considered "the" man when it came to testing and determining things like we are talking about. He combined real world test results with theory to show what a particular bow was capable of and how making changes to arrow weight affected speed and kinetic energy. He mainly published bow reports, but he also wrote some general articles on the subject. He is sort of the grandfather of bow testing.

Here is a quote that I think applies and is a view that is shared by many in the world of archery.
http://www.grandviewoutdoors.com/bow-reports
"This archive of award-winning Bowhunting World Bow Reports written by the most-respected Bow Test guru on the planet—Archery Hall-of-Famer Norb Mullaney—is ready to help."[/quote]

Thanks for the lesson on mr. Mullaney. It looks like he contributed greatly to the field.

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Re: Are faster bows wounding more deer?

Unread postby Dhurtubise » Mon Jul 01, 2013 8:25 am

Schultzy wrote:
As far as heavy arrows vs light arrows- us traditional bow hunters have proved that point time and time again. Unfortunately speed sells now In the archery Industry rather then efficiency. A person can have both with today's compounds. When my body tells me my recurve days are over I'll go back to a compound with a heavy arrow and add the speed of these compounds of today to that and my arrow/bow combo Is going to be outstanding!! I don't understand why more won't do It. I kid. I know why, the speed thing. ;)


Yes! Emphasis on Yes. Full agreement from a physical standpoint.

A lot of numbers being thrown out that doesn't give an accurate picture of the bow's real ability without an understanding of their actual meaning/ repercussions on the shot.
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Re: Are faster bows wounding more deer?

Unread postby trdtnlbwhntr » Mon Jul 01, 2013 2:08 pm

How many of these light arrows are tuned to the bow to support that energy transfer from limb to arrow?
I guess what I am asking is this, does a stiffer, heavier shaft retain the transferred energy better than that of a lighter arrow? How much of the arrows energy is lost in flight due to the archers paradox?

Does a bow shooting a heavy arrow at 40 yards with a lower KE carry more downrange force than a lighter arrow shot with a higher KE at 80 yards?
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Re: Are faster bows wounding more deer?

Unread postby Schultzy » Mon Jul 01, 2013 4:04 pm

trdtnlbwhntr wrote:How many of these light arrows are tuned to the bow to support that energy transfer from limb to arrow?
I guess what I am asking is this, does a stiffer, heavier shaft retain the transferred energy better than that of a lighter arrow? How much of the arrows energy is lost in flight due to the archers paradox?

Does a bow shooting a heavy arrow at 40 yards with a lower KE carry more downrange force than a lighter arrow shot with a higher KE at 80 yards?
Here's something to think about. Every spring a bunch of us get together and do some stump shooting. Most of us are traditional guys but one guy has a bowtech pulling 60lbs. He's shooting just under a 400 grain arrow. He said he's pushing right around 310 fps. Anyhow we take some long shots while stump shooting (It's fun). I remember one particular shot very well and will never forget It. The shot was like 80 some yards we figured. When the bowtech guy shot his arrow started loosing speed very noticeably at about 40 to 45 yards. He shot short about 10 yards of the small evergreen bush we were shooting at. By the time his arrow got to It's ending point Is was pretty much dead. I could not believe how much energy (momentum) that his arrow lost. I've never been Impressed with light arrow set ups but that right there just confirmed my thoughts and beliefs. When I shot my arrow with my 58lb recurve It really didn't loose much speed. It came out slow (150 fps) and ended slow. I too missed the target. I was shooting a 720 grain 340 FMJ. I looked at him and said you can have your light arrow. ;)
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Re: Are faster bows wounding more deer?

Unread postby hunter_mike » Mon Jul 01, 2013 5:00 pm

I believe in the heavier arrows too. This thread has been pretty eye opening. I used to use the big aluminum shafts but they got too inconvenient to use after a while. Used to use the ACC's (Aluminum-Carbon Composite) but I was in college and opted for cheaper arrows. Now I'm thinking I should probably change up some things. It would be really interesting if someone did some experimenting with some super heavy arrows and a chronograph and calculated the momentum they are getting from varying arrow weights with the same bow.
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Re: Are faster bows wounding more deer?

Unread postby trdtnlbwhntr » Mon Jul 01, 2013 8:22 pm

Dont miss understand what I was saying. I am a heavy arrow type of guy as well. I shoot Beman ICS 300's tipped with a 100gr brass insert and a 200gr head. I leave my arrows full length and intentionally shoot an over spined arrow for my longbow so that I can weaken the spine just a hair to fit with the heavier heads. Like you mentioned it may not be the fastest setup in the world, but it will bust through shoulders and ribs like they didnt exist.
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Re: Are faster bows wounding more deer?

Unread postby DEERSLAYER » Mon Jul 01, 2013 9:00 pm

Dhurtubise wrote:...It's just that the original article referenced in the first post focuses on momentum as a measure/indicator of potential pass through as opposed to KE. The article stipulates (rightly) that a slower heavier arrow out of the same bow will have greater momentum to counteract the resistance of the animal's tissues against the arrow tip moving forward and through the body

I guess I got confused (and off topic). I thought you were referencing my response to this:
DEERSLAYER wrote:
JoeRE wrote:Actually guys, Lou what you describe is exactly why KE is a great measure of knock down power of a bullet (where most tissue damage is caused by the "shock" transferred from the bullet to whatever it hits). Arrows depend on the ability to continue to travel in a straight line against resistance from the tissue and bone it is slicing - the definition of linear momentum - to achieve complete penetration, unless your arrow has about 1,000 ft-lbs of KE with your arrow (that is how much is often recommended for deer size game from a bullet) the "knock down power" associated with KE isn't really important. A lighter fast arrow can have more momentum than a slower heavy arrow if it is a lot faster, but weight has an equal say in the matter. KE is more effected by speed.

I think out of a bow kinetic energy is more affected by weight because a bow transfers energy to a heavy arrow more efficiently than a lighter one.

Now that I have confused myself on what I was talking about I will get off that horse. lol



DEERSLAYER wrote:
DEERSLAYER wrote:...Norb Mullaney was a highly respected engineer that did independent bow testing for about three decades. He retired several years ago, but his work is still well respected. He was considered "the" man when it came to testing and determining things like we are talking about. He combined real world test results with theory to show what a particular bow was capable of and how making changes to arrow weight affected speed and kinetic energy. He mainly published bow reports, but he also wrote some general articles on the subject. He is sort of the grandfather of bow testing.

Here is a quote that I think applies and is a view that is shared by many in the world of archery.
http://www.grandviewoutdoors.com/bow-reports
"This archive of award-winning Bowhunting World Bow Reports written by the most-respected Bow Test guru on the planet—Archery Hall-of-Famer Norb Mullaney—is ready to help."


Dhurtubise wrote:...Thanks for the lesson on mr. Mullaney. It looks like he contributed greatly to the field.

One of the thing's about Mr. Mullaney's bow test results that sticks out in my mind is almost all of the manufactures claims about bow speed were exaggerated by varying amounts. I found that the manufacturers speed ratings where only useful for comparing bows within their own product line and only useful as a general comparison among their competitors. Just something to keep in mind for anyone that like's to split hairs 8-)
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Re: Are faster bows wounding more deer?

Unread postby hunter_mike » Tue Jul 02, 2013 5:37 am

Dhurtubise wrote:
On the other hand a faster bow will obviously produce grater momentum in the same arrow, but how much. When you read the literature on a bow, they use the KE value to quantify their bows. It makes sense because this value should be relatively consistent regardless of your choice of arrow weight. However I think that overall this value is misunderstood, and at least a little misleading for your average hunter.

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This is exactly the concept that really clicked for me and made me realize that momentum is the quantity you want to optimize in your hunting bow rig.

I remember that: Potential Energy = Kinetic Energy - Waste energy from friction & inefficiency

-Potential energy is the energy you induce when you draw your bow back. When you are at full draw you have induced the maximum potential energy your bow can capacitate. This amount of energy is always the same for your particular bow no matter what type of arrow or setup you are using. The only way to increase your potential energy is to increase your draw weight. Potential energy is simply a force time a distance. (60lb draw weight*29 inch draw length) (I realize its more complicated than that because of the draw cycle and let-off)

- The waste energy and friction is basically an amount of energy that is a function dependent on the efficiency of your bow, friction between your arrow rest and arrow and any other energy that is converted into hand shock energy you can feel and sound energy you can hear.

- Kinetic energy is basically whatever energy is leftover after you deduct the wast energy. According to the equation above in blue, this kinetic energy amount will be pretty much the same no matter what type of arrow or projectile you are launching. Obviously in reality it does vary a bit. (you can feel the difference in hand shock when you shoot a big heavy arrow vs. when you dry fire your bow.)

So if kinetic energy is pretty much always constant what do you have control over? MOMENTUM

Momentum = mass*velocity

An arrow with more momentum will have more penetrating power because it will want to keep moving more than an object with less momentum. Therefore it is more resistant to slowing down from air resistance and tissue and bone

Anyone care to take it from here?
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Re: Are faster bows wounding more deer?

Unread postby Bowhunting Brian » Tue Jul 02, 2013 6:02 am

hunter_mike wrote:
Dhurtubise wrote:
On the other hand a faster bow will obviously produce grater momentum in the same arrow, but how much. When you read the literature on a bow, they use the KE value to quantify their bows. It makes sense because this value should be relatively consistent regardless of your choice of arrow weight. However I think that overall this value is misunderstood, and at least a little misleading for your average hunter.

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This is exactly the concept that really clicked for me and made me realize that momentum is the quantity you want to optimize in your hunting bow rig.

I remember that: Potential Energy = Kinetic Energy - Waste energy from friction & inefficiency

-Potential energy is the energy you induce when you draw your bow back. When you are at full draw you have induced the maximum potential energy your bow can capacitate. This amount of energy is always the same for your particular bow no matter what type of arrow or setup you are using. The only way to increase your potential energy is to increase your draw weight. Potential energy is simply a force time a distance. (60lb draw weight*29 inch draw length) (I realize its more complicated than that because of the draw cycle and let-off)

- The waste energy and friction is basically an amount of energy that is a function dependent on the efficiency of your bow, friction between your arrow rest and arrow and any other energy that is converted into hand shock energy you can feel and sound energy you can hear.

- Kinetic energy is basically whatever energy is leftover after you deduct the wast energy. According to the equation above in blue, this kinetic energy amount will be pretty much the same no matter what type of arrow or projectile you are launching. Obviously in reality it does vary a bit. (you can feel the difference in hand shock when you shoot a big heavy arrow vs. when you dry fire your bow.)

So if kinetic energy is pretty much always constant what do you have control over? MOMENTUM

Momentum = mass*velocity

An arrow with more momentum will have more penetrating power because it will want to keep moving more than an object with less momentum. Therefore it is more resistant to slowing down from air resistance and tissue and bone

Anyone care to take it from here?


I agree. KE is a marketing tool. KE looks better because it is not a decimal number like momentum is. any of todays bows can get the job done. people think the need a high KE or try to change their set-up so they can raise their KE, when in reality, if they want to increase their chance of a pass through, all they have to do it raise the number of grains on their arrow.
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Re: Are faster bows wounding more deer?

Unread postby hunter_mike » Tue Jul 02, 2013 6:18 am

Bowhunting Brian wrote:
hunter_mike wrote:
Dhurtubise wrote:
On the other hand a faster bow will obviously produce grater momentum in the same arrow, but how much. When you read the literature on a bow, they use the KE value to quantify their bows. It makes sense because this value should be relatively consistent regardless of your choice of arrow weight. However I think that overall this value is misunderstood, and at least a little misleading for your average hunter.

[ Post made via iPhone ] Image


This is exactly the concept that really clicked for me and made me realize that momentum is the quantity you want to optimize in your hunting bow rig.

I remember that: Potential Energy = Kinetic Energy - Waste energy from friction & inefficiency

-Potential energy is the energy you induce when you draw your bow back. When you are at full draw you have induced the maximum potential energy your bow can capacitate. This amount of energy is always the same for your particular bow no matter what type of arrow or setup you are using. The only way to increase your potential energy is to increase your draw weight. Potential energy is simply a force time a distance. (60lb draw weight*29 inch draw length) (I realize its more complicated than that because of the draw cycle and let-off)

- The waste energy and friction is basically an amount of energy that is a function dependent on the efficiency of your bow, friction between your arrow rest and arrow and any other energy that is converted into hand shock energy you can feel and sound energy you can hear.

- Kinetic energy is basically whatever energy is leftover after you deduct the wast energy. According to the equation above in blue, this kinetic energy amount will be pretty much the same no matter what type of arrow or projectile you are launching. Obviously in reality it does vary a bit. (you can feel the difference in hand shock when you shoot a big heavy arrow vs. when you dry fire your bow.)

So if kinetic energy is pretty much always constant what do you have control over? MOMENTUM

Momentum = mass*velocity

An arrow with more momentum will have more penetrating power because it will want to keep moving more than an object with less momentum. Therefore it is more resistant to slowing down from air resistance and tissue and bone

Anyone care to take it from here?


I agree. KE is a marketing tool. KE looks better because it is not a decimal number like momentum is. any of todays bows can get the job done. people think the need a high KE or try to change their set-up so they can raise their KE, when in reality, if they want to increase their chance of a pass through, all they have to do it raise the number of grains on their arrow.


Ok. I agree with that except when you increase the mass of your arrow, you are decreasing your velocity too. Therefore ther has to be a certain optimum point where your arrow will be so heavy that it starts to actually decrease your momentum and hurt you. Thats not my opinion, its math and physics. I would like to find that point.
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Re: Are faster bows wounding more deer?

Unread postby Uncle Lou » Tue Jul 02, 2013 6:46 am

This is a pretty interesting topic and some good opinions and facts in here.

Although maybe slightly off topic, when Deerslayer posted the specs on the Strother Wrath, I cant get the decibels they cite in the chart out of my head. That is the quietest levels I have ever seen (note I said seen, I have never heard a bow that quiet).

Then I want to bring up what Hunter Mike posted in blue
Potential energy = Kinetic Energy - Waste energy from friction & inefficiency.

Noise is a big indicator of loss of energy or inefficient transfer. You should be able to notice a big difference in noise when putting additional weight on your arrow. It was mentioned a few times about heavier arrows using more bow energy.

Now I got to look into that decibel claim on the Strother, that is such a low value it is hard to believe. I suspect a typo or the sound meter is farther away than the standard for that measurement. If it is true, that is an unbelievable breakthrough. Most quiet bows are 80+/- dB. It is also a logarithmic scale which makes it a couple orders of magnitude quieter
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