Arrow penatration problems

[El Coyote]

Simply due to boredom, I'm gonna ask this.

If I have an arrow that weighs 417 grains, and has a speed of 299 fps, I have 82.8 lbs of K.E.

What is the "Momentum" of my set-up?

55 but i cheated. What bow is that?

[rocky]

55 but i cheated. What bow is that?

What is the difference in penetrating potential of 82.8. lbs of K.E., and .55 momentum?
Bowtech Prodigy, 29-72 lbs.

[rocky]

We shot an arrow that weighed 385 grains, 310 fps, with a K.E of 82.17.
What is the momentum of this arrow weight and speed?

[enewman]

We shot an arrow that weighed 385 grains, 310 fps, with a K.E of 82.17.
What is the momentum of this arrow weight and speed?

.530. Going some where arnt you. And I do agree. But

[rocky]

.530. Going some where arnt you. And I do agree. But

No, not really going anywhere, BUT, just wondering what the penetration potential difference is with all these numbers.
Both numbers,(K.E. and Momentum) are simply measurements of penetrating potential, and simply wondering if one of these formulas trumps the other, and why.

[muddyfuzzy]

What is the difference in penetrating potential of 82.8. lbs of K.E., and .55 momentum?
Bowtech Prodigy, 29-72 lbs.

if you are comparing the two, it could be a lot. Now we know this isn't the case with your set-up but humor me for a second. I could get 82 ft/lbs of ke out my turbo pretty easy. shoot a 350 grain arrow at 325, no problem for that bow what so ever. Those numbers would give me right at 82 ft/lbs. Now conversely look at the 419 @ 299. This set-up by my calcs is right @ 83 ft/lbs, very comparable in the KE department. Now there is a reason you don't hunt with that 350 grain arrow, that reason is momentum.........the 419 @ 299 is simply a more efficient killing arrow. That's just the way I see it, but I think you feel the same too based on your selection.

[El Coyote]

Well I don't know where he's going. My z7x is 276 with a 420g arrow 51 momentum and 70ke. Has worked great for me on hogs and deer. It's the main reason why I haven't bought another bow. I was looking at the Prodigy.

[enewman]

No, not really going anywhere, BUT, just wondering what the penetration potential difference is with all these numbers.
Both numbers,(K.E. and Momentum) are simply measurements of penetrating potential, and simply wondering if one of these formulas trumps the other, and why.

K.E. Is amount of energy that is in all directions on impact. Momentum is the amount of energy in one direction.

This is the way I see it. The 417 gn arrow is .55 and the 385 is .53. So the numbers don't look like much, but that is a big difference.

Now will you and me see that difference. Prolly not ever. With it being .53 to .55

But I have seen it on shooting hogs. The differance on .56 and .63. Same speed same head. .56 not a pass. The .63 complete pass.

[rocky]

if you are comparing the two, it could be a lot. Now we know this isn't the case with your set-up but humor me for a second. I could get 82 ft/lbs of ke out my turbo pretty easy. shoot a 350 grain arrow at 325, no problem for that bow what so ever. Those numbers would give me right at 82 ft/lbs. Now conversely look at the 419 @ 299. This set-up by my calcs is right @ 83 ft/lbs, very comparable in the KE department. Now there is a reason you don't hunt with that 350 grain arrow, that reason is momentum.........the 419 @ 299 is simply a more efficient killing arrow. That's just the way I see it, but I think you feel the same too based on your selection.

Well, we all know that a heavier arrow "maintains" better than a lite arrow.
What I question is at what point does 'Momentum' take over 'K.E.'
We all know that speed is to some extent an accuracy enhancer on longer shots, so at what point do we decide to give up speed, for a better "momentum or K.E." number, if both numbers are simply "penetrating potential" numbers, and either are well within killing potential?
We would all like to shoot 600 grain arrows, 300 FPS, but physically for most, it's simply not possible.

If we simply select one number/ formula to base our arrow selection on, we're compromising at some point.
Some say " I want to stay above X fps, so I have to stay below X grains of arrow weight.

[Pushbutton2]

No, not really going anywhere, BUT, just wondering what the penetration potential difference is with all these numbers.

Both numbers,(K.E. and Momentum) are simply measurements of penetrating potential, and simply wondering if one of these formulas trumps the other, and why.

Here's my limited understanding.

KE is in all directions.
I tend think of it like the cavitation a firearm causes in gel block.

Momentum is in a specific direction.
Like a hot knife through butter.

[muddyfuzzy]

Well, we all know that a heavier arrow "maintains" better than a lite arrow.
What I question is at what point does 'Momentum' take over 'K.E.'
We all know that speed is to some extent an accuracy enhancer on longer shots, so at what point do we decide to give up speed, for a better "momentum or K.E." number, if both numbers are simply "penetrating potential" numbers, and either are well within killing potential?
We would all like to shoot 600 grain arrows, 300 FPS, but physically for most, it's simply not possible.

If we simply select one number/ formula to base our arrow selection on, we're compromising at some point.
Some say " I want to stay above X fps, so I have to stay below X grains of arrow weight.

You are spot on. I build a lot of arrows, there is a reason that most of the builds result in an arrow from 420-440 grains......its just a nice happy medium. In most modern bows with average draw lengths it produces a trajectory that is acceptable to most and makes decent KE and momentum. There is the added benefit of running up the FOC and we can really do that with a light GPI shaft. I personally shoot a 440, another nice middle of the road set-up. Today it hit 283 which is giving me .55 momentum and 78 ft/lbs of KE which is a nice-well rounded arrow in all regards......................except the FOC...................its a little weird................@ 22%.

I just ask people what they want out of their equipment then build to suit, offer advice when solicited but at the end of the day folks want what they want. I just personally think a well rounded approach is best for most folks.

[enewman]

I may have looked into what rocky was asking. This is what I thought he was getting at. If I have a lite arrow. That has an momentum of .55. And an arrow that is heavy but momentum is the same .55. Then why shoot slow when you can shoot fast.

Ok let's start by saying this can not happen from the same bow. No matter what bow you shoot. The heavy arrow will always have more momentum.

Now let's take two bows. Say 350 ibo and a 350 arrow. Momentum is .543. Now same bow just adding 40 gn now arrow is 390 took momentum to .583. That is a lot.
Now a bow with ibo 330. With 350 gn arrow. Momentum is .512 Now put an 390 gn arrow momentum is .548. A 425 gn arrow is now .575.

so as you can see no matter what momentum goes up. So if you have an high ibo bow. You can shoot a lighter arrow and it will penetrate as good as a lower ibo bow with an heavy arrow. All them numbers was based on ibo number arrow gn numbers at 70 lb pull at 30 in draw and nothing on the string.
This is part of the reason I shoot a heavy arrow. The other is my bow is very quiet at the shot.

[rocky]

Here's my limited understanding.

KE is in all directions.
I tend think of it like the cavitation a firearm causes in gel block.

Momentum is in a specific direction.
Like a hot knife through butter.

I disagree.
Both are measurements of force to push the head thru mass.
The head will weigh (in most cases) between 85 and 150 grains, with shafts weighing more, so we have more mass pushing the head through the material, regardless of what that material is.
If I will agree to anything, more total mass is more penetrating potential,( if speed is irrelevant), but I'm not really sure this is true.

[enewman]

Well, we all know that a heavier arrow "maintains" better than a lite arrow.
What I question is at what point does 'Momentum' take over 'K.E.'
We all know that speed is to some extent an accuracy enhancer on longer shots, so at what point do we decide to give up speed, for a better "momentum or K.E." number, if both numbers are simply "penetrating potential" numbers, and either are well within killing potential?
We would all like to shoot 600 grain arrows, 300 FPS, but physically for most, it's simply not possible.

If we simply select one number/ formula to base our arrow selection on, we're compromising at some point.
Some say " I want to stay above X fps, so I have to stay below X grains of arrow weight.

Momentum never takes over K.E. In archery K.E. Should never be look at.

But where do we start. In my experance. I know that I start getting good results at around .56 momentum. So that is a number I use. And I talk to people about
Now is that an absolute number no. People kill everyday with a lot less.

[rocky]

Momentum never takes over K.E. In archery K.E. Should never be look at.

But where do we start. In my experance. I know that I start getting good results at around .56 momentum. So that is a number I use. And I talk to people about
Now is that an absolute number no. People kill everyday with a lot less.

If you were to choose to shoot below 250 FPS, couldn't you build an arrow that produced higher momentum numbers?