# Arrows: light vs heavy and penetration



## Bowmania (Jan 3, 2003)

This is probably stupid to get into, but I have a statement that I think will be hard to refute. Got into this discussion on another thread, so I googled "arrow penetration". Sure enough the first one I clicked on showed a light arrow beating a heavy. Like the video of OSB - rest his soul. The next 5 or 6 showed heavy beating light.

BUT in one of them I was familiar with the light arrow. The diameter of the light was larger than the heavy. Hardly fair to the light arrow, but it got me to thinking. I think it's probably impossible to do a scientific test - at least for the average guy. First of all you'd have to have a shooting machine. Next, you'd need two arrows. These two arrows are where most of the problems would stem. They'd have to be the same diameter, AND the same FOC. Obviously a different spine - heavy arrow being stiffer. Get all these things together and they have to shoot bullet holes through paper - tuned. That is a pretty tough bill to fill. Impossible in my mind, because you'd have to tip load the stiffer arrow to make it fly true giving it a higher FOC.

So, I think that physics shows us that a heavy arrow makes a bow more efficient (more energy is transferred to the arrow) and that a heavy arrow looses less momentum as it travels down range. Can someone tell me how a light arrow that starts out with less and looses what it has faster than a heavy arrow can out penetrate the heavy arrow? ALL OTHER THINGS EQUAL.

Bowmania


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## jkm97 (Jul 8, 2004)

Good post. Shot from the same bow, heavier arrows will out penetrate light ones, assuming all arrow characteristics are equal. Simple physics, momentum trumps KE.


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## Easykeeper (Jan 2, 2003)

This is an interesting link:

http://archeryreport.com/2011/03/arrow-penetration-testing-real-bows-real-arrows-real-results/


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## Frankenbean (May 25, 2013)

Ballistics is always a hot topic it seems, among firearms as well. Penetration varies based on a whole variety of variables. In bullets for example a heavier and slightly faster bullet may penetrate LESS than a lighter, slightly slower bullet if you compare a hollow point to an AP round for example (penetration and wound channel diameter are separate, yet related). Arrows are the same, and in order to have a fair comparison the shaft diameter and the arrow head and fletching would need to be exactly the same to eliminate variables. And the target would have to be a clean block of ballistic gelatin for each shot.

It's really a matter of kinetic energy AND momentum combined with other factors; and the goal of the test would be to eliminate those other factors so only K and p remain so the relationship between mass, velocity and momentum (p) can be determined. Assuming both arrows are EXACTLY the same, aside from their mass and velocity, the arrow with the BEST BALANCE of K an p will have the best penetration. Keep in mind that K and p are related through mass and velocity, so they're not some mutually exclusive entities. Much like in an engine or motor, where people think "do you want torque, or horsepower" as though they're separate. They're not, horsepower is a relationship of torque expressed as a value involving time. Similarly, K is expressed as a relationship of momentum over mass: http://physics.ucsc.edu/~josh/6A/book/momentum/node3.html

http://www.physicsforums.com/showthread.php?t=195119 A discussion over just this topic exactly. It's not nearly as simple as "do heavier arrows or lighter arrows penetrate better?" The answer is, it depends. It depends on how much the mass and velocity change for each arrow, and how those mass and velocity changes effect both K and p.


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## JINKSTER (Mar 19, 2011)

Bowmania said:


> Can someone tell me how a light arrow that starts out with less and looses what it has faster than a heavy arrow can out penetrate the heavy arrow? ALL OTHER THINGS EQUAL. Bowmania


First?...I don't think it's "a stupid question" at all...and quite the contrary when one takes into account all physical aspects (which is tough in itself)...as like you stated with the difs in diameter?...in my mind?...that's just one of "Many Constants" that would need to be in place to conduct such a test and yield any results that could be considered "conclusive"...as some other constants would be...

1. FOC: (like you mentioned)

2. Point: Style/Type/Geometry

3. Shaft Surface: and this is one that gave me pause with OSB's claimed results as he used both wood grain coated and bare CF shafting and this alone can make a huge difference via the "friction coefficient" of the two differing surfaces..as while one might tend to slip and slide through target media?..the other may "bind"..such as on a water soaked phone book...so?...both shaft surfaces should be consistent as well.

4. And of course a consistent target media.

That said?...I'll admit this...Overall?...I have noticed that my 315gr cheetahs tend to sink deeper into my bales than my 515gr GT's...both very close in diameter...both bare CF shafting.....both doning screw-in combo points...both very close in FOC...to the point that it supports OSB's findings...that lighter, faster arrows penetrate deeper...as in my mind and experience just stated?..they do...and even though the mathematician in me wants to believe otherwise?...(mass X's velocity and all that?)....the physicist in me argues based on results in that the mathematician is overlooking one very important factor that in lay terms is the age old moniker...

*"SPEED KILLS"*

as the mathematician is left scratching the bald spot on his head while the physicist reminds him of this little anomaly known as the...

*"DECELERATION FACTOR"*

simply put?...it takes the faster arrow..."longer to stop".

Take for instance the Japanese Katana...AKA "Samurai Sword"....light, swift and capable of slashing through media much more proficiently that what a heavier, slower sword design may...especially the last few inches of it's lightening fast tip...and why?....because it takes longer for that speed to dissipate (and/or be brought to a stop).

But here's where things get real murky...that being...*"Target/Media Selection"*

As while the Japanese Samurai Katana was extremely well known for it's ability to "Slice" with it's lightening fast speed?...meanwhile back in the middle east?....Muslim Warriors were infamous for a sword of their creation as well....one that weighed upwards of 20#s...affectionately known as "The Scimitar Sword"....a sword that could crush it's way through shields and armor...and it was considered a Holy Feat when said warriors were able to dispatch a Christian Opponent by halving their body vertically from the crown of their head too and through their groin with a single blow...Two very renowned and respected sword designs with two very different methods of employing them...now why did I just type all that?...for clarity...ready?...cause here it comes...

*IMNSHO?:* Unless you're wearing blue tights and a red cape with the nickname of Superman?...and/or possess the ability of X-ray vision?....choice of arrow weight?...whether it be heavy or light?...is null and void for the following reasoning...

If I hit "Bone or Scapula/Shield" on the way in?: I want a heavy arrow.

If I make a "Soft Tissue Only" strike?: I want a light, fast one.

and since I haven't been blessed with X-ray vision?...I figure this way....

I got "No Bones" sticking with "HEAVY"! :laugh:

cause that way?...it just don't matter...what kind of "matter"...my arrow needs to penetrate to execute it's mission. 

all I got and L8R, Bill. :cool2:


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## Frankenbean (May 25, 2013)

Well, let's use a real world comparison, just to show some known real world tests for penetration....not arrows, but relevant none the less. WWII tank guns, which were designed and tested specifically to penetrate. The guns in question were tested against a steel plate angled at 30* to simulate the front glacis plate of sloping tank armor. German tank guns in this case.

The main gun on the infamous Tiger tank was the 88mm KwK 36 L/56. The main gun on the Panther tank was the 75mm KwK 42 L/70. Comparing the same ammo type, APCR (armor Piercing Composite Rigid).

The 88mm Tiger gun fired a 16lb APCR at just over 3,000fps. The 75mm Panther gun fired a 10.5lb APCR at almost 3,700fps.

At ranges of 1,500m or less, the smaller and faster Panther gun projectile penetrated steel plate armor more effectively. At ranges beyond 1,500m it was roughly similar penetration. 

The 88mm Tiger round had both higher kinetic energy AND higher momentum. And yet it had LESS penetration on average, than the smaller, lighter and faster 75mm Panther round (which had 15% more penetration at close range).

So, what does that tell us? It tells us that both projectile diameter and velocity play a more important role than kinetic energy or momentum. The faster projectile that had LESS kinetic energy and LESS momentum, had MORE penetration. That means it's not as simple as "which arrow penetrates better, lighter or heavier."

Like I said, the answer is "it depends." Personally, if I wanted maximum penetration from an arrow, I'd go for the arrow with the smallest diameter, that had the smallest arrow head width, with the lowest frictional coefficient and the highest velocity.

Only NOW we're getting into another issue....wound channel. If you're trying to kill a living creature, such as an animal....penetration alone is pointless if you hit nothing vital. You need to strike something vital, primarily the nervous or cardiovascular system, in order to bring the target down abruptly. Then you get into LARGER arrow heads that make LARGER wound channels that have a higher chance of striking a vital system and disabling the target. You need both penetration AND adequate wound channel, as well as proper shot placement.


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## kegan (Aug 28, 2006)

I think this whole thing just brings up the real key to the whole debate: you can never truly tell! There are so many variables that it's nearly impossible for someone to really tell another person what will and what won't work. 

We can run numbers all day but when we're out shooting we can all see what works best for us. There are lots of examples of guys getting exceptional performance with light arrows- and there are always lots of examples of guys getting poor performance with ANY arrow. Two great hunters who were devoted enough to film their hunts are good examples: Denny Sturgis Jr. and Rick Welch. Two great guys and great hunters, and both shooting relatively heavy bows (at least 60#) and both heavy and light arrows, respectively. Both have published video footage of them NOT getting complete pass throughs. Obviously, there is no end all to beat all conclusion. Best we can do is use a set up we can tune to a tight tolerance and have confidence in when we take it afield.

What I'd like to know is if there's a series of cheap and easy tests a person could do at home that would simulate ACTUAL game. Would water jugs work, or would you have to make ballistic jelly? Some of the more experienced hunters would be much appreciated here!


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## completepassthru (Feb 3, 2008)

When shooting deer and most any bow arrow weight is not a concern in my opinion. Shoot the arrow you like in the correct spine and go hunt. 

I started out hunting with 450gr arrows my first year of bowhunting. The next year i dropped to 400grs. 2 yrs. later dropped down to 350-360grs. 

4yrs ago dropped to 335grs. and the last 2yrs. 310-315gr. arrows. I have continued to get passthrus with big 2in. 3blade mechanicals with no problems whatsoever..

Shoot heavy if you like they will get the job done. I just like a light arrow flying at a faster speed.


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## 206Moose (Apr 29, 2007)

From my experience as a guide light vs. heavy really isn't the problem. Poke a hole through both lungs and you will find your deer within 100 yards. Every argument fixed vs. mechanical, heavy vs. light boils down to shot placement. Take high percent shots within your capabilities and you don't have anything to worry about. That being said I prefer heavy arrows and fixed blades. Why? As mentioned earlier you will often encounter the scapula and I believe that combination gives you an advantage in that situation.


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## whack&stack (Oct 15, 2007)

I just decided to forego the whole which works best and having to decide if I wanted heavy or fast. So now I shoot heavy and fast


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## Widgeon (Jul 17, 2009)

All my testing has shown the following:

1) Heavier/slower arrows have more KE/momentum then lighter faster arrows at launch from the same bow and continue to have more at all distances throughout the flight.
2) Heaver/slower arrows have better penetration in nearly all materials, foam being the exception (and just so happens to be the primary target material people try to do penetration testing with) of course the arrows for testing must have the same outside characteristics.

There are some things I am continuing to investigate, including how speed affects brittle impacts (IE arrows vs. plywood) but overall, heavier has won hands down.

When it comes down to it, shot placement, properly tuned/spined arrows and a good quality broadhead are all more important.


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## Frankenbean (May 25, 2013)

Smaller, faster projectiles have more penetration compared to a heavier, slower projectile. That's of course provided that the differences in velocity and mass aren't so profound as to result in huge differences in energy. That said, the weight and velocity differences in arrows are small enough to not really matter in the equation. So generally speaking with bows...the faster projectile will have more penetration, regardless of weight. You likely can't change weight and velocity enough to matter.

That however does NOT address the issue of the wound channel. An arrow with a larger arrow head will weigh more than one with a smaller arrow head (assuming all else is equal). While the smaller lighter arrow may penetrate better, there is the issue of wound channel. The larger arrow head will make a larger (wider) wound channel. Larger wound channel means larger chance of disabling the CNS or CVS.

Consider this....the military has started issuing some of the old M-14's to the field. The .223 in the M4 carbine has been making pass-throughs on Johnny Jihads in the field. It has 0 issues penetrating a person. They HAVE however been making pass-throughs without stopping the targets (this is however partly a result of the ammunition type used). The .308 in the M-14's make pass-throughs also....but the larger caliber and higher kinetic energy, mean a MUCH larger wound channel (this is also a result of hydrashock, which typically wouldn't be encountered with an arrow). The .308 is guaranteed to stop a target in 1 hit, the .223 is not. Neither one has a penetration problem.

Small and fast may penetrate really well...but penetrating power and killing power aren't necessarily the same thing.


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## LBR (Jan 1, 2004)

From the research I've done, guides for dangerous/thick skinned game require heavy arrows. Critters like Cape Buffalo, Asiatic Buffalo, etc. I talked to one guide who had several horror stories about light arrows.

Not exactly scientific, but I trust experience.


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## whack&stack (Oct 15, 2007)

They have arrow weight requirements in Africa for a reason. Those requirements are not as light & skinny as possible. This should tell you something.


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## jusoldave (Apr 28, 2012)

Hidden By Design said:


> From my experience as a guide light vs. heavy really isn't the problem. Poke a hole through both lungs and you will find your deer within 100 yards. Every argument fixed vs. mechanical, heavy vs. light boils down to shot placement. Take high percent shots within your capabilities and you don't have anything to worry about. That being said I prefer heavy arrows and fixed blades. Why? As mentioned earlier you will often encounter the scapula and I believe that combination gives you an advantage in that situation.


Couldn't have said it better myself.

I'm no guide, but I've shot a lotta arrows at a lotta animals for a lotta years. I started out with moderately heavy arrow/head combos, and never have had one cause me to consider changing from that norm.


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## Widgeon (Jul 17, 2009)

Frankenbean said:


> Smaller, faster projectiles have more penetration compared to a heavier, slower projectile. That's of course provided that the differences in velocity and mass aren't so profound as to result in huge differences in energy. That said, the weight and velocity differences in arrows are small enough to not really matter in the equation. So generally speaking with bows...the faster projectile will have more penetration, regardless of weight. You likely can't change weight and velocity enough to matter.


No offense, but I completely disagree with this, so does physics, and so does all of my testing (with the exception being penetration into foam, which favors faster arrows for various reasons.)

When comparing firearms projectiles to each other, so many other factors play into it. Charge, ballistic coefficient, sectional density, bullet geometry, gun characteristics, etc. etc. etc. Doing so is no different than comparing the penetration from my Vector Turbo with Axis arrows and Montec heads to someone else's recurve with wood arrows and glue-on Zwickey broadheads. To do proper comparisons, the outside dimensions and characteristics of the arrows must be identical.


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## Frankenbean (May 25, 2013)

Like I said, there's a difference between penetrating power and killing power. The goal isn't the best penetration possible. It's the best killing power possible (if we're talking about killing game). Penetration is typically also measured in terms of soft tissue, using ballistic gelatin that simulates typical animal/human tissue. You have to have SOME benchmark to standardize measurement, otherwise what do we measure penetration through....brick walls? Tank armor? The sun?

Unfortunately, in these types of discussions things are usually much more complex than something as simple as mass and velocity.

Dangerous game represents a whole other aspect of ballistic penetration (for both arrows and bullets). That's because unlike most common game that people hunt, dangerous game if more akin to a person wearing a bullet proof vest. Just like handgun rounds have known penetration values against soft issue....that completely changes once used against soft tissue with a ballistic vest over it. Heavier arrows with more energy are more effective against dangerous game for the same reason heavier bullets with more energy are effective against ballistic vests, because most dangerous game has a hardened tissue layer that isn't typical soft tissue (so the standard method of measuring penetration doesn't entirely apply). It's a highly specialized tissue, somewhat akin to a fingernail/toenail on a person....only much, much thicker. Soft tissue is highly elastic and self lubricating, so an arrow or bullet will pass through it fairly easily. Hardened "armored" tissue on dangerous game is much less elastic and presents much higher friction to anything trying to pass through. That's why it's easy to cut your finger with a knife, but not so easy to cut through the fingernail.

That's where additional kinetic energy helps, it gives the "hitting power" needed to punch through the outer layer and still retain enough energy to maintain velocity. Energy and momentum are conserved in a system, velocity is not. In this case, the system would be the arrow and the armor layer....their total combined energy is the same before and after impact. It takes a fixed amount of energy to pass the arrow head through the armor, making a hole in the process. If enough energy exists in the arrow, some is transferred to the armor when penetrating (to overcome the tension in the tissue and the friction), and the rest remains in the arrow and can be measured as velocity. The faster the arrow is going after penetrating the armor, the farther it will penetrate through the soft tissue underneath. If the arrow's energy is too low, and it's not able to pass through the armor, then all of it is transferred from the arrow to the armor....and the arrow stops. This is essentially a basic physics work equation, it takes a certain amount of energy to do the work of passing a given object through another given object. 

Remember again, penetration is measured in ballistic gelatin; scientific measurements of penetration anyway, rather than anecdotal measurements. The energy requirements to pass a projectile through such a medium some given distance is relatively low, so kinetic energy and momentum are less important (but are still important none the less, for various reasons). But, once you start passing through non standard objects...dangerous game "armor" or ballistic vests, steel plates, brick walls etc; the energy requirements change and the now standard method of measuring penetration becomes partly or completely useless. Now kinetic energy becomes much more important.

The real question shouldn't be "which penetrates better, lighter faster arrows, or slower heavier arrows;" it should be "what type of arrow is most effective for accomplishing _______ ." If we're talking simply about penetration...then penetrating what? If the ultimate goal while hunting is maximum penetration....then why don't you hunt with an x-ray machine?

If we're talking about penetration generally...then we can put it this way:
"When comparing 2 projectiles of different mass and velocity, assuming both contain enough kinetic energy and momentum to pass through the target medium effectively; then the faster projectile, which is usually the lighter projectile, will penetrate better."

And all we end up with, is a rather vague generalization. But the key part would be "pass through the target medium effectively," since we need to compare apples to apples. But in life, we have apples...and oranges. This gets into using the right tool for the right job. Just like you wouldn't use a rifle to shoot a tank....you wouldn't use a light DW bow with a light arrow to shoot a Rhinoceros.


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## benofthehood (May 18, 2011)

I miss Sharpy ...


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## MAC 11700 (Feb 22, 2011)

Shot placement is very important. ..but so too is making sure the arrow maintains it's intended path if some bone is hit. 

Correctly spined arrows don't kick out as easily as arrows that are barely in range. 

There are lots of things to take into account...not just speed due to arrow weight. 

Mac


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## MAC 11700 (Feb 22, 2011)

Franknbean...

You better go back and study ballistics a little better. ..momentum is calculated as a derivative of the velocity. .as such it matters greatly. Without sufficient mass..there won't be sufficient momentum. 

Mac


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## Frankenbean (May 25, 2013)

MAC 11700 said:


> Franknbean...
> 
> You better go back and study ballistics a little better. ..momentum is calculated as a derivative of the velocity. .as such it matters greatly. Without sufficient mass..there won't be sufficient momentum.
> 
> Mac


Huh? Maybe you're taking what I said out of context? I said that you likely can't change the weight or the velocity of the arrow enough, by simply going to a lighter or heavier arrow, to cause significant changes to kinetic energy or momentum enough to effect penetration as much one might expect. You'd simply have to go to a heavier bow that shoots the arrow noticeably faster. In other words I'm saying people are too concerned about just changing the weight of the arrow, and not concerned enough about in increasing the velocity (by going to a heavier bow).

Momentum (linear) is mass times velocity. Velocity is equally as important as mass. With any amount of mass and 0 velocity, momentum is 0. With any amount of velocity and 0 mass, momentum is 0. I stated the relationship of mass and velocity in momentum earlier, and provided a link to a university physics department with the equations. Did you not read all of what I posted? You can decrease mass and increase velocity such that momentum stays the same, yet kinetic energy will go up.


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## Frankenbean (May 25, 2013)

Widgeon said:


> No offense, but I completely disagree with this, so does physics, and so does all of my testing (with the exception being penetration into foam, which favors faster arrows for various reasons.)
> 
> When comparing firearms projectiles to each other, so many other factors play into it. Charge, ballistic coefficient, sectional density, bullet geometry, gun characteristics, etc. etc. etc. Doing so is no different than comparing the penetration from my Vector Turbo with Axis arrows and Montec heads to someone else's recurve with wood arrows and glue-on Zwickey broadheads. To do proper comparisons, the outside dimensions and characteristics of the arrows must be identical.


How does physics disagree, when I provided links to the calculations and real world examples that prove exactly what I said? Decreasing mass such that velocity increases, causes changes to momentum and kinetic energy....if the mass goes down and the velocity goes up such that momentum remains the same, kinetic energy increases. The example of the tank guns I gave shows that even with LESS kinetic energy and LESS momentum, a faster projectile can have MORE penetration. The point I was making was what I've stated, momentum and energy alone are not the key factors in penetration. And that penetration isn't the key factor in killing power Your second part is correct, you have to eliminate all the variables (which I said earlier) and compare ONLY the changes in mass and velocity with everything else remaining the same.

And no offense, but as far as "your own testing," unless it was done into ballistic gelatin (a chemically engineered and QA controlled substance to provide homogenous, consistent resistance to penetration to allow test repeatability, that accurately simulates human/animal tissue), with arrows that were weighed and measured on calibrated lab scales, fired from a bow that was set up in a jig that actually measured draw weight and length, as well arrow angle, in order to provide consistent repeatability, observed by multiple people to ensure the testing wasn't altered out of parameter, and the results across multiple samples recorded....it's anecdotal at best. I'm not trying to be rude. But a real test like this is done under EXTREMELY rigid testing standards to ensure that the ONLY variables are those being tested.

I'm talking about real, scientific testing that has been done under lab based conditions, and recorded. Not shooting at water bottles or hay bales, or foam targets. None of which are engineered to provide uniform consistency to ensure that the target itself doesn't alter the test results.

I actually would like to see someone do that, and publish the results so there would be definitive answers to epople's questions about penetration, weight, velocity etc.


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## dougedwards (Sep 5, 2010)

So often I read that this whole ordeal is just a matter of simple physics and physics mandates that a heavier arrow will ALWAYS out penetrate a lighter one....just because of the law of physics. 

That is NOT the law of physics. It depends. The efficiency levels of our bows have restrictions. A 10 pound arrow shot from a 45 pound longbow would not penetrate very well. That is because the bow is not capable of projecting very quickly. 

Normally it is true that almost any traditional bow will shoot a heavier arrow further into most mediums than it can project a lighter one. The law of physics demands that it be so. But not because a heavier arrow will always out penetrate a lighter one. It is because of the efficiency parameters of the bow that is capable of doing so. 

Now, the law of physics does mandate that a heavier arrow being projected at the same speed as a lighter one will out penetrate but that is not what I am reading in most of these posts. Let's state the law of physics for what it is, not what we want it to be.

Doug


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## Lil Okie (Mar 25, 2008)

benofthehood said:


> I miss Sharpy ...


Did he decide not to come back? Or did they give him life..


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## Bowmania (Jan 3, 2003)

The reason I thought this is stupid (not a stupid questions) is because of the above. I knew that it would go on and on from both sides. AND never get a real answer.

We don't need any discussion on whitetails for penetration - they're not big enough - penetration on one is never a problem if you hit the spot.

Whach&Stack has one of the most relevant comment in my mind - and there's nothing scientific about it. It does give a place to go for and answer SA - Why did they make that law.

Another question to the light guys. If you sent 15 K on a brown bear hunt would you use a 350 grain arrow? 450? 550?

BUT most important, nobody came close to answering my original question.

Bowmania


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## LBR (Jan 1, 2004)

> BUT most important, nobody came close to answering my original question.


That's what happens when you ask a "hard" question that goes directly against the grain with some folks. Don't feel like the Lone Ranger--I've had many more questions ignored/changed/spun than than answered here. The nature of message boards I reckon.



> Can someone tell me how a light arrow that starts out with less and looses what it has faster than a heavy arrow can out penetrate the heavy arrow? *ALL OTHER THINGS EQUAL*.


The answer is simple--it can't.


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## dougedwards (Sep 5, 2010)

Bowmania said:


> The reason I thought this is stupid (not a stupid questions) is because of the above. I knew that it would go on and on from both sides. AND never get a real answer.
> 
> We don't need any discussion on whitetails for penetration - they're not big enough - penetration on one is never a problem if you hit the spot.
> 
> ...


 The original question did not specify anything really? Did not specify from the which bow or draw weight or the shape and nature of anything that is being considered. With such a vague question why is it an enigma that you would receive such nebulous responses. Be more specific and I bet you will receive more specific types of responses.

Doug


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## Widgeon (Jul 17, 2009)

Frankenbean said:


> How does physics disagree, when I provided links to the calculations and real world examples that prove exactly what I said? Decreasing mass such that velocity increases, causes changes to momentum and kinetic energy....if the mass goes down and the velocity goes up such that momentum remains the same, kinetic energy increases. The example of the tank guns I gave shows that even with LESS kinetic energy and LESS momentum, a faster projectile can have MORE penetration. The point I was making was what I've stated, momentum and energy alone are not the key factors in penetration. And that penetration isn't the key factor in killing power Your second part is correct, you have to eliminate all the variables (which I said earlier) and compare ONLY the changes in mass and velocity with everything else remaining the same.
> 
> And no offense, but as far as "your own testing," unless it was done into ballistic gelatin (a chemically engineered and QA controlled substance to provide homogenous, consistent resistance to penetration to allow test repeatability, that accurately simulates human/animal tissue), with arrows that were weighed and measured on calibrated lab scales, fired from a bow that was set up in a jig that actually measured draw weight and length, as well arrow angle, in order to provide consistent repeatability, observed by multiple people to ensure the testing wasn't altered out of parameter, and the results across multiple samples recorded....it's anecdotal at best. I'm not trying to be rude. But a real test like this is done under EXTREMELY rigid testing standards to ensure that the ONLY variables are those being tested.
> 
> ...


You completely contradict yourself with your own example of tank projectiles, claiming they show a difference in penetration across different values of KE then turn around and state that all variables must be controlled. The projectiles you compare from the tanks are shot under different conditions and are different projectiles physically, thus that example is void under your own argument.

Here is more about the physics:

http://archeryreport.com/2011/01/heavy-vs-light-arrows-speed-power/

Anytime a projectile moves through a fluid or fluid behaving material, geometries being equal, the heavier arrow will always have the advantage in retaining a higher percent of its energy and momentum. For energy losses not due to fluid drag, the arrow that starts with the most energy will have more penetration potential. 

I get the impression that you are throwing out equations and pointing to them without really understanding how they relate to the real world. With bows, as arrow weight goes up, so does the efficiency of the bow. Thus heavier arrows leave the bow with more momentum and more KE. KE increases are modest in most cases but momentum increases are quite significant, in both stick bows and compounds. If it takes a certain amount of energy to perform the task of penetrating a certain distance, which do you think will have the advantage? The arrow with more energy to begin with or less? Yes, I realize that is a massive over-simplification of the issue, but it gets the point across. This is also not even considering the advantage of a slower moving projectile with more sectional density over a faster one with less sectional density (see article posted above).

So yes, physics on paper does 100% support a slower, heavier arrow having more penetration potential. My testing has shown the same and though it may not be in ballistics gel (which btw is ripe with its own problems in testing and being consistent), it is under controlled conditions to the point that I have high confidence in it. I will continue to do more testing as well and will publish it in the future.


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## Frankenbean (May 25, 2013)

Widgeon said:


> You completely contradict yourself with your own example of tank projectiles, claiming they show a difference in penetration across different values of KE then turn around and state that all variables must be controlled. The projectiles you compare from the tanks are shot under different conditions and are different projectiles physically, thus that example is void under your own argument.
> 
> Here is more about the physics:
> 
> ...


Again, out of context. My point with the tank guns was to show that kinetic energy and momentum ALONE aren't sufficient indicators of penetrating power. It was to show that even a lower K and p round can have higher penetration. Obviously there are differences between the 2, caliber being one. THAT'S why those types of variables need to be controlled. If the goal is to examine how mass and velocity changes alone effect penetration, then all the other variables have to be controlled such as diameter, material used so on and so forth. And the problem even with that, is "all else being equal" is generally impossible. Like you said, as the arrow weight increases the bow becomes more efficient, so that would have to be considered.

Also, human/animal tissue is not fluid, it's elastic and lubricated. Yes, you are correct, a higher p projectile WILL penetrate farther through a fluid because of the fluid drag (which is almost non present in animal tissue), and how it functions against the p of the projectile. But consider this....the higher the p of a projectile, the lower the rate of deceleration as it passes through a target. Lower p means a higher rate of deceleration. If the lower p projectile has high enough starting velocity....even though it's decelerating at a faster rate, the higher initial velocity may be enough to allow it to travel farther over a longer period of time before stopping. So a lighter projectile may or may not penetrate better, depending on all the variables. That's why I said it depends. If you were to conduct testing with arrows by changing the weight say, 10 grains at a time and measure penetration shot from a setup that controls all the possible variables, and then graph it....you'd likely find that the graph would be entirely non linear. There may even be more than one arrow weight that provides optimum penetration. What you would find, is that when comparing projectiles within a specific weight range, that changes in velocity would have a larger impact on penetration than changes in mass.


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## Frankenbean (May 25, 2013)

Bowmania said:


> The reason I thought this is stupid (not a stupid questions) is because of the above. I knew that it would go on and on from both sides. AND never get a real answer.
> 
> We don't need any discussion on whitetails for penetration - they're not big enough - penetration on one is never a problem if you hit the spot.
> 
> ...


It's not a stupid question, it's just much more complex than a simple yes or no. The answer is "it depends." "All things being equal" is almost impossible to achieve. A lighter arrow may or may not penetrate better, depending on a variety of variables. And it's an equation where changing a single variable, causes other variables to change as well. The more momentum (p) a projectile has, the harder it is to slow down. However, if the initial velocity of a lower p projectile is high enough, even though it slows down at a faster rate; it may still travel farther, simply by virtue of sufficiently high initial velocity (even at a faster rate of deceleration, you still need X time to decelerate a projectile at Y velocity). In order to answer your question directly, you'd have to do the math between 2 separate arrows and see which one penetrates more in that particular instance.

Generally speaking though with projectiles, velocity and projectile design are far more important for penetration than mass, p and K. For example, compare 2 bullets with the same mass and velocity....and therefore the same p and K, but 1 hollow point and one AP. Obviously the AP round will penetrate much farther, even though mass and velocity are identical. In that case, projectile design alone is the determining factor. Typically when comparing similar projectiles of different mass and velocity, the lighter faster projectiles generally out penetrate slower heavier ones in typical test media. But not always. You can see that by looking at published test data from bullet manufacturers for the same projectile of various grains. If you graphed penetration vs. mass/velocity of given projectiles...you'd find a non linear graph. And somewhere within the range of available masses there'd be one (or perhaps more) projectiles with the optimum mix of mass and velocity.


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## Widgeon (Jul 17, 2009)

Frankenbean said:


> But consider this....the higher the p of a projectile, the lower the rate of deceleration as it passes through a target. Lower p means a higher rate of deceleration. If the lower p projectile has high enough starting velocity....even though it's decelerating at a faster rate, the higher initial velocity may be enough to allow it to travel farther over a longer period of time before stopping. So a lighter projectile may or may not penetrate better, depending on all the variables. That's why I said it depends. If you were to conduct testing with arrows by changing the weight say, 10 grains at a time and measure penetration shot from a setup that controls all the possible variables, and then graph it....you'd likely find that the graph would be entirely non linear. There may even be more than one arrow weight that provides optimum penetration. What you would find, is that when comparing projectiles within a specific weight range, that changes in velocity would have a larger impact on penetration than changes in mass.


The highlighted section in red above is where you have gone wrong. Look at it from an energy aspect: (warning, HUGE over-simplification coming up to illustrate the point) Suppose we are looking at penetration in a deer and that we start with a 100 KE slower, heavier arrow and an 80 KE faster, lighter arrow (no units, just nice easy numbers) and that it takes 40 to penetrate the hide and a rib, then 10 for each additional inch of penetration. Arrow 1 with 100 KE will penetration 6in past entry and arrow 2 with 80 KE will penetrate 4in past entry. It takes a certain amount of energy to go work, in this case the work costs 10 KE per inch of penetration regardless of speed. When that energy is spent, it's GONE. This is also regardless of the fact that the lighter arrow with less KE is going to experience more resistance due to it's higher initial speed and may shed energy even faster.

Speed does not carry an arrow through the distance of penetration, energy does.

With regards to the text highlighted in blue, refer to the momentum/KE/weight charts here:

http://archeryreport.com/2009/11/arrow-kinetic-energy-momentum-archer/


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## Frankenbean (May 25, 2013)

Widgeon said:


> The highlighted section in red above is where you have gone wrong. Look at it from an energy aspect: (warning, HUGE over-simplification coming up to illustrate the point) Suppose we are looking at penetration in a deer and that we start with a 100 KE slower, heavier arrow and an 80 KE faster, lighter arrow (no units, just nice easy numbers) and that it takes 40 to penetrate the hide and a rib, then 10 for each additional inch of penetration. Arrow 1 with 100 KE will penetration 6in past entry and arrow 2 with 80 KE will penetrate 4in past entry. It takes a certain amount of energy to go work, in this case the work costs 10 KE per inch of penetration regardless of speed. When that energy is spent, it's GONE. This is also regardless of the fact that the lighter arrow with less KE is going to experience more resistance due to it's higher initial speed and may shed energy even faster.
> 
> Speed does not carry an arrow through the distance of penetration, energy does.
> 
> ...


That's the problem with over simplifications though...it ignores real issues. Your example assumes that the faster arrow has lower kinetic energy, which isn't always the case. Remember that energy changes directly with mass, but changes with the square of the velocity. 2x the mass is 2x the energy, 2x the velocity is 4x the energy. Changing both mass and velocity changes K in various ways, depending on how much mass and velocity change. So a lighter faster arrow may have less momentum and more kinetic energy, or less momentum and less kinetic energy, it really depends on how heavy and how fast the arrows are moving. It also assumes that a fixed amount of energy is shed from the projectile over a fixed distance, which may or may not be the case. It also completely ignores momentum. Remember that momentum determines how rapidly an object can be decelerated with a fixed amount of force, if 2 objects have the same velocity but different momentum...the higher p object will go farther before stopping, due to a lower rate of deceleration (assuming the same resistance). If an object with lower p has high enough initial velocity, it may take longer/farther to slow it to a stop. Provided all the assumptions of your simplification are correct, then yes...the faster, lower p lower K arrow would penetrate less.

I think what we could agree on though, is that when penetration begins, some initial minimum K is required to overcome the resistance of what we're shooting into. Otherwise penetration would be 0 and the arrow would bounce off.

"This is also regardless of the fact that the lighter arrow with less KE is going to experience more resistance due to it's higher initial speed and may shed energy even faster." This actually raises an interesting point (heh). I disagree, somewhat. In all likelihood, the faster projectile will probably cut with the arrowhead more efficiently, resulting in less energy required per distance unit. Frictional losses increase as the square of velocity, so the faster arrow would experience an increase in friction that the slower arrow would not. However, given that soft tissue is self lubricated....the frictional values would be so low as to not matter enough. Shooting through a really thick hide though, that isn't the typical self lubricated soft tissue....then frictional losses would probably matter, maybe even a lot.


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## Widgeon (Jul 17, 2009)

Frankenbean said:


> That's the problem with over simplifications though...it ignores real issues. Your example assumes that the faster arrow has lower kinetic energy, which isn't always the case. Remember that energy changes directly with mass, but changes with the square of the velocity. 2x the mass is 2x the energy, 2x the velocity is 4x the energy. Changing both mass and velocity changes K in various ways, depending on how much mass and velocity change. So a lighter faster arrow may have less momentum and more kinetic energy, or less momentum and less kinetic energy, it really depends on how heavy and how fast the arrows are moving. It also assumes that a fixed amount of energy is shed from the projectile over a fixed distance, which may or may not be the case. It also completely ignores momentum. Remember that momentum determines how rapidly an object can be decelerated with a fixed amount of force, if 2 objects have the same velocity but different momentum...the higher p object will go farther before stopping, due to a lower rate of deceleration (assuming the same resistance). If an object with lower p has high enough initial velocity, it may take longer/farther to slow it to a stop. Provided all the assumptions of your simplification are correct, then yes...the faster, lower p lower K arrow would penetrate less.


Stop right there! I can 100% say with all certainty that if you take two arrows of differing weights that are properly spined/tuned to a bow, and shoot them both without changing anything on the bow, the heavier arrow will have more KE and momentum. If you read the article I posted, you can see the actual data behind some very precise testing on this. That article has only the tip of the iceberg of the reams of data I have showing this across many bows, compound and stick, heavy draw weight and light. This should not be up for debate. Also, if you read this article: http://archeryreport.com/2011/01/heavy-vs-light-arrows-speed-power/ you will see that the heavier arrow also maintains a higher percent of its KE and momentum downrange. The heavier arrow WILL hit the animal with more KE and momentum, period. This is due to the increased efficiency of bows with heavier arrows and the fact that faster/lighter arrows will experience a higher drag force (proportional to the square of the velocity!) You can't look at a formula and say "Oh! that variable is squared, therefore it must have a bigger impact!"




Frankenbean said:


> "This is also regardless of the fact that the lighter arrow with less KE is going to experience more resistance due to it's higher initial speed and may shed energy even faster." This actually raises an interesting point (heh). I disagree, somewhat. In all likelihood, the faster projectile will probably cut with the arrowhead more efficiently, resulting in less energy required per distance unit. Frictional losses increase as the square of velocity, so the faster arrow would experience an increase in friction that the slower arrow would not. However, given that soft tissue is self lubricated....the frictional values would be so low as to not matter enough. Shooting through a really thick hide though, that isn't the typical self lubricated soft tissue....then frictional losses would probably matter, maybe even a lot.


Physics to back this up? Dry/surface friction is INDEPENDENT of velocity and relies on the friction constant and the normal force between the bodies. Lubricated/fluid resistance will favor the slower object with more sectional density. Once again, read the articles that I posted; they have both theory and real world testing results.


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## Frankenbean (May 25, 2013)

Ok, so if bow efficiency always increases with a heavier arrow such that K and p are always higher with a heavier arrow...why doesn't everyone always shoot the heaviest arrow they can from the bow if the energy is the most important factor for penetration? Or more specifically...how are some people getting better penetration with lighter arrows than with heavier arrows fired from the same bow? And yes, some people are getting better penetration with heavier arrows than lighter ones. There is data on both sides that can be picked in and of itself to try to prove a point. My point is that energy and momentum alone aren't the sole factors that determine penetration, and there are results to prove it where people conduct tests with lighter arrows and get better penetration.

It gets back to what I said about "it depends." K and p are important, but so is velocity and projectile design. The highest energy arrow isn't necessarily the best penetrating one, and the fastest possible arrow (lightest possible, lowest energy) is necessarily the best penetrating one either. I haven't finished reading everything, but I did find it surprising that kinetic energy always increases with a slower heavier arrow, at least in their tests conducted. I am curious if there are any cases where the faster arrow has higher energy. Not something I would have expected, but even with that considered....kinetic energy is not a direct indicator of penetration in a given target.

As for frictional losses, coefficients of friction are fixed values for given objects yes, but total friction is a combination of those coefficients combined with pressure applied and speed/force at which shearing action takes place. The harder you press your hands together, and the faster you rub them...the more friction you create.


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## Widgeon (Jul 17, 2009)

Frankenbean said:


> Ok, so if bow efficiency always increases with a heavier arrow such that K and p are always higher with a heavier arrow...why doesn't everyone always shoot the heaviest arrow they can from the bow if the energy is the most important factor for penetration? Or more specifically...how are some people getting better penetration with lighter arrows than with heavier arrows fired from the same bow? And yes, some people are getting better penetration with heavier arrows than lighter ones. There is data on both sides that can be picked in and of itself to try to prove a point. My point is that energy and momentum alone aren't the sole factors that determine penetration, and there are results to prove it where people conduct tests with lighter arrows and get better penetration.


*IF* you have two arrows that are IDENTICAL in every way concerning external characteristics, similar FOC and are tuned properly to the bow, the heavier arrow will win. However, if you are comparing a heavier, wood arrow with an obsidian chipped broadhead to a lighter Easton Axis with a Slick Trick, I'm sure you can guess what my bet is on. Of course some lighter arrows will penetrate better and there are other factors! However, everything being equal besides the weight, heavier will win.



Frankenbean said:


> It gets back to what I said about "it depends." K and p are important, but so is velocity and projectile design. The highest energy arrow isn't necessarily the best penetrating one, and the fastest possible arrow (lightest possible, lowest energy) is necessarily the best penetrating one either. I haven't finished reading everything, but I did find it surprising that kinetic energy always increases with a slower heavier arrow, at least in their tests conducted. I am curious if there are any cases where the faster arrow has higher energy. Not something I would have expected, but even with that considered....kinetic energy is not a direct indicator of penetration in a given target.


Those articles are actually mine and I did all the testing personally. I have yet to find a bow where lighter=more KE/momentum. There are exceptions to everything, but in this case the evidence is very consistent.



Frankenbean said:


> As for frictional losses, coefficients of friction are fixed values for given objects yes, but total friction is a combination of those coefficients combined with pressure applied and speed/force at which shearing action takes place. The harder you press your hands together, and the faster you rub them...the more friction you create.


Surface/kinetic friction (two solids sliding against each other) absolutely does not depend on speed at any rational speed or anything we are dealing with here. This is well known physics. You are only increasing the heat you feel through increased pressure and the build up of heat as you rub them faster, over the SAME skin the you previously rubbed over and added heat to, it is NOT dependent on how fast you rub them.

Skin friction (friction between a solid and a fluid) is the friction that is part of the drag force calculation. This is the friction that goes UP with the SQUARE of the velocity and is the friction that favors the slower, heavier arrow. It is also a big part of why lighter arrows slow down at a faster rate than heavier arrows during their flight.


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## BarneySlayer (Feb 28, 2009)

I think we need to separate some issues here.

Penetration, as agreed, will be somewhat of a complex issue. You have mass, you have velocity, you have cross sectional density, you have friction, you have the variables of the penetrated materials, all of which makes it very fun to discuss in theory, but in any case, if you're trying to talk in simple terms, there will always be exceptions.

Now, that said...

KE is expressed in foot-pounds. That is because 40 foot-pounds of kinetic energy is exactly the energy it would take to push 40 pounds 1 foot, or 1 pound 40 feet, or however you'd like to manipulate your numbers. So, f the opposition to penetration was a fixed resistance, KE would tell you _exactly_ what kind of penetration you would get. Force*Distance. An object can have less momentum, which will translate into less ability to impart movement on another object, but as I think Jinks pointed out, a faster moving object covers more distance while it's slowing down.

As far as bow efficiency, yes, the energy is proportional to the square of the velocity, and IF your arrow half the weight resulted in twice the speed, you would in fact have a lighter arrow with more KE. But that doesn't happen. Keep in mind that as the arrow gets lighter, the increase in velocity does not scale in a linear fashion. Even if you had the same efficiency, arrow at half the weight will not go twice as fast, because while twice as fast with the same mass does have 4 times the KE, it _also takes 4 times the KE to get something moving twice as fast_. If you take an object with a given rate of acceleration, it will take 4 times the distance to get up to twice the speed as it did to get to a given speed. Distance = 1/2(acceleration)(time^2). F=MA. Energy (the ability to do work) = force*distance. Plug away to your heart's content, the equations haven't changed, so far as I know, when we're not near the speed of light.


A good way to think of how the weight affects the efficiency of the bow is to consider the energy that is actually going into the bow itself. That is, the frictional losses (which will be pretty constant, relatively), and also the kinetic energy put into the moving of the limbs. The heavier the arrow, the lower proportion of the total energy that goes into moving the limbs. Why? Because the heavier the arrow, the slower the limbs travel, the less energy is siphoned into the limb movement which then dissipates through vibration, sound, heat, yada yada... In essence, the slower the bow moves, the less energy it absorbs into itself.

But, like I said, when you get into the projectile penetrating the medium.... easier to try and see.


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## Frankenbean (May 25, 2013)

For those of you interested....

http://www.ncbi.nlm.nih.gov/pubmed/9751539

Keep in mind, this is from a peer review medical journal. Actual scientific testing that was conducted in a lab, then subjected to blind review by medical experts to determine if it met scientific muster for publication in medical literature.

Notice their results and conclusions? "In nonbone tissue, the penetration depth was substantial (17-60 cm) and depended on velocity and especially on the type of arrowhead." The conclusion is was that wound severity was based on shot placement and arrow head design.


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## JINKSTER (Mar 19, 2011)

Ya know?..I really thought my "sword analogy" was pretty good...the light and fast samurai katana slices and dices while the mass of the weighty scimitar smashes and crashes it's way through bones and all...so I guess if ya opt for light arrows?...and the deer runs off with one part way in'em?..you could always say..."Well I guess I musta Hit a Bone" :laugh:

other than that?...

:deadhorse :blah:


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## Frankenbean (May 25, 2013)

Well, honestly....here's my take at the end of the day. From having worked in EMS and seen people struck by projectiles (typically bullets) and stabbed....

Vital organs don't care what the kinetic energy or mass or velocity of an offending object is. All that matters is if a vital organ is disrupted. Much ado about nothing, or yes, beating a dead horse.

While high energy can be devastating in it's own right...some of the deadliest attacks have been those with the lowest kinetic energy. The lowly .22 has put tons of people on morgue slabs in the US, though partly due to being the most prolific caliber...even though it's one of the lowest energy pistol rounds available. All you need to do is disrupt the cardiovascular system or central nervous system....and the target is dead.

You could put a high speed, low weight arrow through the eye socket of an animal, and kill it instantly. Or you could put the most powerful arrow in existence through and through an animal, and somehow avoid injuring any organs entirely. The arrow could miss organs, and yet break the rib and the bone could puncture the lung and be fatal. I've seen that with bullets....the bullet missed everything except a rib, and the rib fragment put the hole in the lung. I've also seen people that had bullets pass completely through their chest and manage to avoid hitting anything that mattered.

Heavy projectiles and light projectiles can be equally as deadly. It just depends on what it hits, and how it hits it.


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## Widgeon (Jul 17, 2009)

Frankenbean said:


> For those of you interested....
> 
> http://www.ncbi.nlm.nih.gov/pubmed/9751539
> 
> ...


Unfortunately there are no details on how and what exactly they did; it would be interesting to see their testing methodology. I have always said and will always say, the primary keys to killing animals and good penetration are:

1) shot placement
2) good quality, sharp broadhead
3) properly tuned equipment 
4) knowing how your equipment performs and what your limitations are

Playing around with arrow weight vs. trajectory and optimizing penetration potential are great things to do IMO, but without the items listed above they are worthless.


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## Frankenbean (May 25, 2013)

Widgeon said:


> Unfortunately there are no details on how and what exactly they did; it would be interesting to see their testing methodology. I have always said and will always say, the primary keys to killing animals and good penetration are:
> 
> 1) shot placement
> 2) good quality, sharp broadhead
> ...


I agree 100%.

I'd like to see the report too, but without access to the PubMed database, oh well. That it was scientifically peer reviewed and published in a journal means they were properly scientific about methodology, so we can be confident that their findings aren't bogus...at least in what they were attempting to examine. I think the important part is that their determination was the most important factor beyond all else, was arrowhead design.


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## JParanee (Oct 13, 2009)

JINKSTER said:


> Ya know?..I really thought my "sword analogy" was pretty good...the light and fast samurai katana slices and dices while the mass of the weighty scimitar smashes and crashes it's way through bones and all...so I guess if ya opt for light arrows?...and the deer runs off with one part way in'em?..you could always say..."Well I guess I musta Hit a Bone" :laugh:
> 
> other than that?...
> 
> :deadhorse :blah:


Bill Japanese swords excel at what they do because of edge geometry and curvature 

If you swing one like a bat it will not perform near as well as if it is used properly

Japanese swords are all different weights and that depends on what era they are from 

When they had to cut thru thick leather Mongol armor they where quite heavy and robust


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## JParanee (Oct 13, 2009)

If your talking about bullet performance in my experience penetration first and foremost comes down to type of bullet meaning solid or soft of expandable 

Next is sectional density. Lets take Teddy R's lion medicine the 405 win 

Neat round adequate performance on big cats and bears but very poor sectional density its a short fat projectile 

Lets take a 375 H&H 

Good ballistics , good sectional density therefore good penetrator 

Lets take two 300 grain solids 

One a 405 and the others 375 

The 375 9 times out of ten will out penetrate the the 405 

Lets look at old Bells pet elephant rifle chambered in 275 Rigby (7X57) great section density and tremendous penetration for a relative light caliber 

He would routinely get feet of penetration thru elephant skulls doing brain shots in a time that will never be repeated when market elephant hunting was the game 

So in bullets type of bullet and speed and sectional density rule the day 

In arrows I take the middle road and shoot just over 500 grains 

No to heavy not to light


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## BLACK WOLF (Aug 26, 2005)

Take one bow, one draw length, 2 arrows of different weight but identical in all other aspects and test penetration...based on my experience and research...there's going to be very little difference in penetration with most target materials.

The only noticable difference I have seen is with heavy bone or wood/plywood which is why I believe heavier arrows are recommended for Dangerous Game of Africa.

I don't think it matters a whole lot with North American Animals.

The number one factor I've seen that can increase the penetrations of a bowhunter's chosen arrow is tuning.

Tune your arrows to the best of your ability and you will have increased your arrow's penetrating potential...whether you using a light or heavy arrow.

Ray :shade:


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## rattus58 (Jul 9, 2007)

Bowmania said:


> This is probably stupid to get into, but I have a statement that I think will be hard to refute. Got into this discussion on another thread, so I googled "arrow penetration". Sure enough the first one I clicked on showed a light arrow beating a heavy. Like the video of OSB - rest his soul. The next 5 or 6 showed heavy beating light.
> 
> BUT in one of them I was familiar with the light arrow. The diameter of the light was larger than the heavy. Hardly fair to the light arrow, but it got me to thinking. I think it's probably impossible to do a scientific test - at least for the average guy. First of all you'd have to have a shooting machine. Next, you'd need two arrows. These two arrows are where most of the problems would stem. They'd have to be the same diameter, AND the same FOC. Obviously a different spine - heavy arrow being stiffer. Get all these things together and they have to shoot bullet holes through paper - tuned. That is a pretty tough bill to fill. Impossible in my mind, because you'd have to tip load the stiffer arrow to make it fly true giving it a higher FOC.
> 
> ...


In my opinion, penetration depends upon the media we're penetrating. If its paper and gelatin, its relevant to paper and gelatin. Where I think penetration matters, is in hunting. Here it is not just penetration but also the broadhead and the arrow doing the pushing. I don't think deer at close ranges is a good medium either, as almost anything will go through them given a fair velocity. Where I think penetration matters is in longer shots, weaker bows, those unfortunate situations where the animal moves or turns towards or away from you about the time you release. 

Heavy arrows are my choice and penetration has never been an issue..... watching my arrow covering 20 yards almost able to watch the rotations is mesmerizing... :grin:


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## rattus58 (Jul 9, 2007)

BarneySlayer said:


> I think we need to separate some issues here.
> 
> Penetration, as agreed, will be somewhat of a complex issue. You have mass, you have velocity, you have cross sectional density, you have friction, you have the variables of the penetrated materials, all of which makes it very fun to discuss in theory, but in any case, if you're trying to talk in simple terms, there will always be exceptions.
> 
> ...


It takes 4 times the energy to move an object at twice the speed.


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## MAC 11700 (Feb 22, 2011)

Someone said to me..there is no law of dimishing returns in one of the several arguements I have entered in on this topic...

Well..they are still wrong..when it comes to shooting animals at various yardages..I'm like many here...I shoot arrows that are tuned exceedingly well..and am not trying to shoot the lightest weight arrow off my 66 lb. bow.unless I am just playing around with it.I've seen light weight arrows off lighter weight bows do exceptionally well on getting pass throughs on light skin game..with close yardages but I have also seen light weight arrows fail on longer shots...I've also seen light weight arrows shot off heavier weight bows (both tuned well enough) not do so well..using the same broadhead..when the yardages were long There is a reason for this..and that is while the light weight arrow/heavier poundage bow shot the lighter arrow well enough to tune..what the arrow wasn't able to do was to not maintain a linear direction of travel when a hard object like heavy bone and gristle (boars sheild plate) by having the tail kick out much more than the heavy arrow heavy poundage bow arrow..This tail kick..is a oscilating motion not linear..and any discussion on this subject really needs to discuss this aspect as well as all the rest..Change the linear travel path of the tail of the arrow by as little as 1" moves the head ..and many forget that fact...doing so can make a normal perfect shot turn very ugly very quickly..and doing so will reduce significantly any penatration the arrow was going to have and then you have a wounded animal running off with a arrow hanging out of it..and that is not something anyone really wants to happen.

I'm sorry for saying this...since I know many won't appreciate it...but...It's all well and good to have pristene lab conditions and perfectly spec'd calibrated ballistic gel..exact yardages ..but it don't mean squat when comparing to actual feild results on game animals.Ballistic gelatin is shot as a static target..and a game animal is anything but static...The mathmaticians will swear being able to control the variables is the only "true scientific" way to test...and they are right..it is..but those results are like putting teets on a boar hog...it might look inviting to the piglets..but ain't really worth a crap to them out in the real world.

There will always be a point of dimishing returns when all the varibles are factored in..especialy longer yardages..and a arrow may be tuned well enough to shoot a light arrow well..but it will always have more tail kick than a heavier weight arrow..and in the real world..having a better spine is a very valuble thing..

Mac


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## Frankenbean (May 25, 2013)

If you're trying to make valid comparisons between 2 things, then other variables need to be controlled....or the comparison is not valid. But yes, it's still just that, a comparison.

As for range, higher kinetic energy/momentum projectiles always have advantages as the range the projectile travels increases. They are definitely more stable, and will retain more velocity at longer ranges. Hence the reason military sniper rounds are both large and fast, eg .50BMG and .338 Lapua (this round currently holds the world record for longest range confirmed kill, at almost 2,500m for anyone interested...just over 1.5 miles).


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## MAC 11700 (Feb 22, 2011)

You can not control all variables in the field. 

You can not control if you hit bone or not. .you can only aim for the correct spot to try to mimize the chances. 

You can not control the naturally occurring varibles of game animals. ..so what I said is valid about putting teet'son a boar.

Mac


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## Frankenbean (May 25, 2013)

If you're testing to see what variables change the outcome, then you have to eliminate other variables. Otherwise you don't know which one had an effect on the result, and by how much. Yes, lab testing doesn't necessarily result in a direct outcome in the field, or real world use. But in most cases it puts you in the ballpark. If it were irrelevant, we wouldn't have modern bullets, ballistic vests, cars, or bows and arrows for that matter.

Lab testing can determine the capabilities of the object you're developing, but it can't determine the environmental variables in which it's used. Proper design however, will attempt to take those into account, and build in some buffer space if possible to mitigate the negative impacts of things you can't accurately control, predict, or test.


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## MAC 11700 (Feb 22, 2011)

Frankenbean said:


> If you're testing to see what variables change the outcome, then you have to eliminate other variables. Otherwise you don't know which one had an effect on the result, and by how much. Yes, lab testing doesn't necessarily result in a direct outcome in the field, or real world use. But in most cases it puts you in the ballpark. If it were irrelevant, we wouldn't have modern bullets, ballistic vests, cars, or bows and arrows for that matter.
> 
> Lab testing can determine the capabilities of the object you're developing, but it can't determine the environmental variables in which it's used. Proper design however, will attempt to take those into account, and build in some buffer space if possible to mitigate the negative impacts of things you can't accurately control, predict, or test.


Yup...it's nothing more than a educated guess

Personally. .I prefer to be a pessimistic optimist. ..by planning for the worst I will be encounter. ..but hoping for the best outcome. .by using common sense instead of relying on lab experiments where the tester purposely elects to narrow down the varibles just fit a single model. 

Thankyouverymuch

Mac


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## Bowbodger (Apr 7, 2011)

Agree 100% with ray and JP by the way I have a 7x57 dandy little rifle. Tune is critical to any bows penetration and performance the better tuned the arrow is the less, the better the flight and the more energy it is going to have coming off the bow and retain downrange. My bows in general wont tune a real light arrow well so I prefer at a minimum 8gpp, 10 to 13gpp seem to work even better and be in the sweet spot for most of my bows. I like bows in the high 30's to low 40's for target 3D low to mid 40's for hunting only whitetail and turkey in my area so I dont need any more than that.

For hunting I will err on the heavy side or 10+Gpp, a heavier object does also have more resistance to a change in direction, deflection due to momentum and sheer mass so its less likely to get deflected in route by a smallish branch etc and less likely to get deflected by bone once it hits the target.

The other plus is every bow I have ever shot is quieter and has less vibration at the shot with a heavier arrow everything else being the same which means easier to tune and less wasted or lost energy.


Jeff




BLACK WOLF said:


> Take one bow, one draw length, 2 arrows of different weight but identical in all other aspects and test penetration...based on my experience and research...there's going to be very little difference in penetration with most target materials.
> 
> The only noticable difference I have seen is with heavy bone or wood/plywood which is why I believe heavier arrows are recommended for Dangerous Game of Africa.
> 
> ...


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## rattus58 (Jul 9, 2007)

Bowbodger said:


> Agree 100% with ray and JP by the way I have a 7x57 dandy little rifle. Tune is critical to any bows penetration and performance the better tuned the arrow is the less, the better the flight and the more energy it is going to have coming off the bow and retain downrange. My bows in general wont tune a real light arrow well so I prefer at a minimum 8gpp, 10 to 13gpp seem to work even better and be in the sweet spot for most of my bows. I like bows in the high 30's to low 40's for target 3D low to mid 40's for hunting only whitetail and turkey in my area so I dont need any more than that.
> 
> For hunting I will err on the heavy side or 10+Gpp, a heavier object does also have more resistance to a change in direction, deflection due to momentum and sheer mass so *its less likely to get deflected in route by a smallish branch etc *and less likely to get deflected by bone once it hits the target.
> 
> ...


I've no quarrel with any of your statement except just one.... the deflection part... Don't kid yourself... a 470 grain lead bullet might not be deflected by a smallish branch and in fact one of deer on lanai drilled right through a 1 1/2" sapling into the deer... but arrows will deflect at the slightest provocation... even 1000 grain arrows. I shot for several years in the guava orchard next door to my house and witnessed this on all sorts of projections... so the moral of my argument... have a "good look" at the path to travel as well as what's beyond... :grin: :beer:


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## Frankenbean (May 25, 2013)

rattus58 said:


> I've no quarrel with any of your statement except just one.... the deflection part... Don't kid yourself... a 470 grain lead bullet might not be deflected by a smallish branch and in fact one of deer on lanai drilled right through a 1 1/2" sapling into the deer... but arrows will deflect at the slightest provocation... even 1000 grain arrows. I shot for several years in the guava orchard next door to my house and witnessed this on all sorts of projections... so the moral of my argument... have a "good look" at the path to travel as well as what's beyond... :grin: :beer:


I'm sure a 470gr bullet wouldn't be deflected either, since that's almost a .50 cal round...it'd be something like a .450 Nitro Express Elephant round. A bullet like that doesn't get deflected....it does the deflecting. The current US military combat round for the M4 (M855A1) is only 62gr. Even the much higher power .308 round is still typically less than 200gr. I think the point he was making is that an arrow with more momentum is less likely to be deflected or will deflect less, than one with lower momentum.


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## rattus58 (Jul 9, 2007)

Frankenbean said:


> I'm sure a 470gr bullet wouldn't be deflected either, since that's almost a .50 cal round...it'd be something like a .450 Nitro Express Elephant round. A bullet like that doesn't get deflected....it does the deflecting. The current US military combat round for the M4 (M855A1) is only 62gr. Even the much higher power .308 round is still typically less than 200gr. I think the point he was making is that an arrow with more momentum is less likely to be deflected or will deflect less, than one with lower momentum.


True... in my opinion... heavy arrows are less likely to ricochet. The do in fact deflect. My arrows have a very shallow FOC... because of their weight... but I'd really like to see a moderate arrow with a well forward cg compared to a heavy normally FOC'd arrow to see which recovered better.


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## MAC 11700 (Feb 22, 2011)

And a heavier arrow is less likely to have any deflection at the target as well. They track better through when any hard bone is hit.

Mac


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## rattus58 (Jul 9, 2007)

MAC 11700 said:


> And a heavier arrow is less likely to have any deflection at the target as well. They track better through when any hard bone is hit.
> 
> Mac


Don't know... I'm usually shooting into buckets, balls, and dirt banks... :grin:


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## Destroyer (Sep 11, 2009)

:icon_1_lol:


:deadhorse


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