Mechanical Broadheads

[Ray]

That's great. Let me know when you can shoot a moose and how it performs.

Back to the Energy and Weight Discussion.

This is good reading for those that think speed and lightweight arrows or energy measurements are the main factors to penetration.

Kinetic energy does not enter directly into any of the calculations relating to penetration. THE KINETIC ENERGY CARRIED BY AN ARROW AT IMPACT HAS NO DIRECT BEARING ON ITS ABILITY TO PENETRATE.

 

If one fills a 5 gallon plastic pail with sand and fires both a .357 magnum and a heavy hunting arrow at it, the bullet will be stopped by the sand, while the arrow will penetrate the pail completely. The .357 magnum handgun has a 158 grain bullet traveling at 1250 fps, for a momentum of 0.83 slug-feet per second, and a kinetic energy of 520 foot-pounds. A 710 grain arrow at 183 fps has only 0.57 slug-feet per second of momentum, and a mere 52 foot-pounds of kinetic energy.

 

These are actual combinations I have used to demonstrate the penetration power of a heavy hunting arrow. Our baseball, with 96.5 foot pounds of kinetic energy, and 1.39 slug-feet per second of momentum, will simply bounce off. What makes the difference?

 

A major factor between the bullet and the arrow is the increased resistance force met by the higher velocity bullet. While the bullet has ten times more kinetic energy, and 37.5% more momentum, than the arrow, its almost seven times higher velocity causes the bullet to be met by nearly fifty times as great a resistance force as that encountered by the arrow!

 

Another major factor between the handgun’s bullet and the arrow (yes, we will get to the baseball shortly) is the longer time period of the arrow’s impulse; which results from its higher mass. Though the arrow is traveling much slower than the bullet, and has less momentum than the bullet, it derives a greater percentage of the momentum it does possess from its mass. It is ‘heavier’.

 

The heavier (and lower velocity) arrow “decelerates” more slowly than the bullet or, if one prefers, it has a longer time period over which the force acts. Remember? Force multiplied by the time it acts equals the impulse. The heavier arrow retains a higher percentage of its force for a longer period of time than does the bullet. The bullet’s total net disposable force, though very high relative to the arrow, is entirely dissipated in milliseconds.

Formulas:

 

Momentum = Mass x Velocity

225218

 

In other words, momentum equals the arrow’s mass, measured in grains, multiplied by the arrow’s velocity, expressed in feet per second, and then divided by 225218. The resultant answer will be expressed in slug-feet per second.

[STIKNSTRINGBOW]

That's great. Let me know when you can shoot a moose and how it performs.

 better yet how about an Elk!!! They work on deer but.... If you shoot a deer through the heart with anything it will die

[Lowedog]

That's great. Let me know when you can shoot a moose and how it performs.

 better yet how about an Elk!!! They work on deer but.... If you shoot a deer through the heart with anything it will die

Wouldn't that apply to an elk also?   

-Lowedog

[Lowedog]

That's great. Let me know when you can shoot a moose and how it performs.

Back to the Energy and Weight Discussion.

This is good reading for those that think speed and lightweight arrows or energy measurements are the main factors to penetration.

Kinetic energy does not enter directly into any of the calculations relating to penetration. THE KINETIC ENERGY CARRIED BY AN ARROW AT IMPACT HAS NO DIRECT BEARING ON ITS ABILITY TO PENETRATE.

 

If one fills a 5 gallon plastic pail with sand and fires both a .357 magnum and a heavy hunting arrow at it, the bullet will be stopped by the sand, while the arrow will penetrate the pail completely. The .357 magnum handgun has a 158 grain bullet traveling at 1250 fps, for a momentum of 0.83 slug-feet per second, and a kinetic energy of 520 foot-pounds. A 710 grain arrow at 183 fps has only 0.57 slug-feet per second of momentum, and a mere 52 foot-pounds of kinetic energy.

 

These are actual combinations I have used to demonstrate the penetration power of a heavy hunting arrow. Our baseball, with 96.5 foot pounds of kinetic energy, and 1.39 slug-feet per second of momentum, will simply bounce off. What makes the difference?

 

A major factor between the bullet and the arrow is the increased resistance force met by the higher velocity bullet. While the bullet has ten times more kinetic energy, and 37.5% more momentum, than the arrow, its almost seven times higher velocity causes the bullet to be met by nearly fifty times as great a resistance force as that encountered by the arrow!

 

Another major factor between the handgun’s bullet and the arrow (yes, we will get to the baseball shortly) is the longer time period of the arrow’s impulse; which results from its higher mass. Though the arrow is traveling much slower than the bullet, and has less momentum than the bullet, it derives a greater percentage of the momentum it does possess from its mass. It is ‘heavier’.

 

The heavier (and lower velocity) arrow “decelerates” more slowly than the bullet or, if one prefers, it has a longer time period over which the force acts. Remember? Force multiplied by the time it acts equals the impulse. The heavier arrow retains a higher percentage of its force for a longer period of time than does the bullet. The bullet’s total net disposable force, though very high relative to the arrow, is entirely dissipated in milliseconds.

Formulas:

 

Momentum = Mass x Velocity

225218

 

In other words, momentum equals the arrow’s mass, measured in grains, multiplied by the arrow’s velocity, expressed in feet per second, and then divided by 225218. The resultant answer will be expressed in slug-feet per second.

Apples to oranges.  Big difference between comparing a bullet fired into sand vs an arrow, than 2 arrows with no difference between them other than what is attached to the end of them.

What would you rather have in your hands with a grizzly charging, your long bow and an 800 grain arrow or a Smith & Wesson 500?   

I gave slug feet per second numbers in my examples before.  Simple fact is a traditional bow of reasonable poundage can not out perform a modern compound no matter how heavy an arrow you want to shoot. 

With that said, I love traditional bows.  I have built a few of my own.  I might go out one day with my compound and the next with my recurve.

The only reason I responded on this thread was to say that to each his own.  If a guy wants to have the latest most high tech set up so be it.  Hunt with what you are happy with and let the next guy do the same.

Now, to Ray who said that a 45 lb longbow shooting fixed will out penetrate a 60lb compound with mechanicals, I would love to put that theory to a test.  You send me the broadheads and I will do the testing and post up results.     I have both bows at those draw weights...

-Lowedog

 

[Ray]

Now, to Ray who said that a 45 lb longbow shooting fixed will out penetrate a 60lb compound with mechanicals

I didn't say it. Ashby did. And it wasn't a 45lb bow. If I recall it was a 40lb vs 60lb. I can dig the report out of my garbage if necessary. Remember it's not about the bow it's all about the arrow and broadhead combined with momentum and impact. The comparison is distracting and I agree with that. I guess if you want to call him  innacurate go ahead. His test is there for you to challenge. He has been doing them for many years and has some credibility. Don't take objection to me if you don't agree with it. Go do your own test and prove it wrong. Then publish your materials for all to see. He's not making money off his studies and has published his work for criticism openly.

A number of things which you hit on were not even representative of what was discussed and are somewhat incorrect. First - when did someone say that a traditional longbow would outperform a compound bow? It's a multi faceted series of variables. More than the bow. Please show me this. I'd probably choose a handgun over a bow when confronted with dangerous animals too but that wasn't the point. The point was understanding the laws of penetration and what factors are involved. What was stated by you earlier I did not even respond to because it was also unclear and not on target regarding the formulas. I think you have chosen to take several things out of context for the sake of your argument and apply them but forget about the other important factors. Which can be construed as an attempt to make someone else's response a lie or false. I am not offended by it. I am used to it when someone feels on the losing end of a debate. A lot of things which you speak to I am not debating. Other than mechanical broadheads will never be stronger than a single piece of steel and to this date they are proven to be inferior in many tests and that there is just reason for them being illegal. That's what you don't like or want to agree with openly but it's not my problem.  You have also implied I was insulting about things which I did not say. I have read what you wrote and do respect your point of view.

Simple fact is a traditional bow of reasonable poundage can not out perform a modern compound no matter how heavy an arrow you want to shoot.  

I could pick this apart but I think I know what you wanted to say. So are you saying a 45 lb compound bow would outperform a 65 lb longbow? Think about it. Again I think I know what you wanted to say. Maybe of equal poundage or something. But remember it's not about the bow. The arrow and broadhead will be factors. Including weight, arrow choice and momentum.

[Lowedog]

Ray, I don't understand why you think I am trying to argue with you.  Like I said I am simply saying that one method is not necessarily better than another.  I was trying to just put some facts out there that would support another point of view.  Not even my own point of view.  Once again, I support all forms of archery.  All forms of hunting for that matter.  I don't care what you or anybody else uses.

My statement that a traditional bow of reasonable draw weight can not out perform a modern compound was simply that.  I guess if you want me to be more specific lets just use IBO figures. 

Give the compound an IBO speed of 325fps which is fairly moderate for todays bows and here are the numbers-
K/E = 82.11 ft lb
Slug-ft/sec = .505

The only stated IBO speed rating for a longbow I could find is for the Martin Venom at 280fps-
K/E = 60.95 ft lb
Slug-ft/sec = .435

All of this is just to show that there are many ways to get the same results in the end.  One way is no better than the other in my opinion.

Hell, if you want to argue then the argument could be made that a person who feels that by using what they think is a superior product could lead them to be more likely to take marginal shots at game. 

Another argument could be made that by using what is being considered an inferior product here in a mechanical that the person using it with the most modern compound set up is far more accurate at a far greater range and can place that BH with pinpoint accuracy thus eliminating the marginal shot and delivering the arrow into the vitals where it will do its job. 

That is if a person wanted to argue.

-Lowedog

[Ray]

Another argument could be made that by using what is being considered an inferior product here in a mechanical that the person using it with the most modern compound set up is far more accurate at a far greater range and can place that BH with pinpoint accuracy thus eliminating the marginal shot and delivering the arrow into the vitals where it will do its job.

Is a compound bow more accurate or the person behind the bow? I have seen guys who could not hit the broad side of a barn at 30 yards.

You can't hit vitals if your arrow does not penetrate far enough. With mechanicals your chances for sustaining integrity of the broadhead are lower and the penetration may be great if they expand and work under their needed circumstances. Otherwise if they do not maintain their structural integrity they will surely not perform nearly as well as desired. They have a long way to go when it comes to comparing them to other broadheads. Studies show why they are illegal.

[Ray]

My statement that a traditional bow of reasonable draw weight can not out perform a modern compound was simply that.

It's the broadhead, arrow and the momentum. Not the bow. The bow only produces the momentum. It does not produce the arrow or the broadhead.

[Ray]

Give the compound an IBO speed of 325fps which is fairly moderate for todays bows and here are the numbers-
K/E = 82.11 ft lb
Slug-ft/sec = .505

The only stated IBO speed rating for a longbow I could find is for the Martin Venom at 280fps-
K/E = 60.95 ft lb
Slug-ft/sec = .435

How could you calculate the slug-ft if there was no arrow weight? This is the sort of thing I have been ignoring from you earlier.

You'll have a hard time proving your thought process like that.

[Lowedog]

First - when did someone say that a traditional longbow would outperform a compound bow? It's a multi faceted series of variables. More than the bow. Please show me this.

I'd bet hands down my products are superior in more ways than one to any gadget prone modern setup. Simplicity is fantastic as well as reliable. I don't need some bow doc to tune my bows and they are capable of penetrating bone, flesh and taking game as well as or better than any modern setup.

I guess you didn't exactly say "out perform".  That is what I thought was implied there. My Bad. 

Simple fact is a traditional bow of reasonable poundage can not out perform a modern compound no matter how heavy an arrow you want to shoot. 

I could pick this apart but I think I know what you wanted to say. So are you saying a 45 lb compound bow would outperform a 65 lb longbow? Think about it. Again I think I know what you wanted to say. Maybe of equal poundage or something. But remember it's not about the bow. The arrow and broadhead will be factors. Including weight, arrow choice and momentum.

So again to go to the numbers for arguments sake. 

Let's go with one of the most modern compounds in the Mathews monster with an IBO speed rating of 360fps and set it to 45lbs with a 28" draw and a 350 grain arrow which would be realistic to hunt with.  Here are the numbers-

290fps
65.38 ft lb K/E
.45 Slug-ft/sec

Back to the Martin Venom and lets give it the same 28" draw at 65lbs with a 650 grain arrow which would be pretty representative of what some one might hunt with.  Numbers-

150fps
32.48 ft lb K/E
.4329 Slug-ft/sec

So yeah I guess a 45 lb compound will out perform a 65lb longbow.

-Lowedog










-Lowedog

[Ray]

So yeah I guess a 45 lb compound will out perform a 65lb longbow.

It can. But it might not if someone chose a heavier or different arrow and better broadhead.

[Lowedog]

Give the compound an IBO speed of 325fps which is fairly moderate for todays bows and here are the numbers-
K/E = 82.11 ft lb
Slug-ft/sec = .505

The only stated IBO speed rating for a longbow I could find is for the Martin Venom at 280fps-
K/E = 60.95 ft lb
Slug-ft/sec = .435

How could you calculate the slug-ft if there was no arrow weight? This is the sort of thing I have been ignoring from you earlier.

You'll have a hard time proving your thought process like that.

IBO rating = 70lb draw weight, 30" draw and a 350gr arrow.

-Lowedog

[Ray]

If all arrows were using the same broadhead it would be an interesting test. The thing about the Ashby tests are that he tests many broadheads side by side. He also tests arrow shafts.

[Lowedog]

So yeah I guess a 45 lb compound will out perform a 65lb longbow.

It can. But it might not if someone chose a heavier or different arrow and better broadhead.

Going heavier with an arrow at that draw weight and draw length just makes the numbers worse.  

Add 200grs and the K/E drops to 13.1 with .314 slug-ft/sec at a dismal 83 fps.  The animal might just run off before the arrow gets there.  

Actually contrary to the heavier is better theory a 550 grain arrow would be the best set up and get you closest to what the compounds numbers are.

183fps
41 ft lb K/E
.447 slug ft/sec

Offer still stands to email you this program.  It is a great tool!

-Lowedog

[Ray]

The important thing to remember is that this is about broadhead performance. Although you may find it a interesting for the sake of a small point that I was not necessarily trying to debate. The point  is not to prove a compound bow is a good performer when we are comparing and discussing broadheads and their ability to perform. If you are going to propose that people use mechanicals on large game then do some testing on elk and moose. Real testing. Not mathematics.

You actually have not proven what you wanted.