KE vs. Momentum

[Rent Outdoor Gear]

Very nice work and thorough investigation - perhaps I have never taken one to the peak of the bell curve and over the top. As for bucksnort's comments, a lot of the difference you're seeing between carbon and aluminum is diameter related. A smaller frontal area generates much higher pressures allowing the arrow (and probably the smaller diameter .22 caliber bullet) to penetrate the surface easier. A smaller diameter shaft with equal force will always yield more penetration. Think thumb tack vs. a nail - much easier to push a thumb tack into a 2x4 by hand than the nail. Pressure = force/area Therefore as area decreases with smaller shaft diameter, the pressure increases.

Next time I do some testing I will definitely have to use a much larger range of arrow weights to see if I can duplicate your results. Thanks for sharing Rebecca!

Coop

 

[larryschwartz]

Coop,

Actually, your pressure example really only applies to the point of the arrow. It would be accurate if you were shooting flat blunt tips with diameters that matched the diameter of the arrow, but it wouldn't apply if you had field points or broadheads. But, your point about the diameter is dead on!

The wider diameter (and therefore circumfrence) arrows will have more surface area which will cause more drag/resistance as it moves through the animals body, which will slow it down and reduce penetration. This is why folks asked if Rebecca used arrows with the same diameter in her testing.

My son and I did a science fair project using this idea, we had three arrows, all within 10 grains of each other, shot from the same bow with the same draw length. So each arrow had pretty much the same KE and we found that as the diameter went up the penetration went down.

Larry

 

[rebecca francis]

Larry,

That is a cool project! I'll bet it was fun too! That is exactly what we determined as well. In my testing, I tested the same diameter arrows against each other at different weights, as well as different diameter arrows. The small diameter ALWAYS out penetrated the larger diameter due to the reduction of drag. The VAP arrow is actually tapered so it really decreases the drag upon penetration.

Anyway, it's all just good, clean, fun! Thanks for your input! You too Coop!

 

[ckleeves]

I have read some pretty interesting stuff about arrow diameter not changing penetration much when it comes to performance on animals. Targets are a different story my vap's get about 3'' more in a fresh 3-d target and I shoot them because I figure it can't hurt but think about pulling an arrow out of a dead animal compared to a target. If not for the broadhead hanging up there is very little resistance.

 

[ckleeves]

http://archeryreport.com/2012/07/penetration-testing-foam-comparing-hunting-penetration/

Edit-Might not have the right page but it is on this site with alot of other good info.

 

[LNGBOWFLYER]

Rebecca, I also found that more times than not the lighter faster arrows penetrate more than slower heavier ones...Back in the mid 90's when bows were just starting to get fast I noticed this... The newer bows shooting the newer lighter carbon arrows were out penetrating the heavier older slower aluminum arrows..

Kinda like how a 22-250 will penetrate more mild steel than a 30-06

I disagree. I've shot at and through a lot of buildings etc and I can tell you that a 7.62mm round penetrates much further through brick, mortar, metal and man dress than a 5.56mm round does.

 

[Gus]

"Kinda like how a 22-250 will penetrate more mild steel than a 30-06"
Huh? don't tell me that you really believe this.

I guess if this were true, the PHs in Africa should be using a 220 swift, 204 Ruger, or a 22-250 as back up guns instead of the 375, 416, 470 and 500 Nitro calibers. those PHs in Africa must have it all wrong based on this logic displayed by some in this thread!

 

[BuckSnort]

"Kinda like how a 22-250 will penetrate more mild steel than a 30-06"
Huh? don't tell me that you really believe this.

I guess if this were true, the PHs in Africa should be using a 220 swift, 204 Ruger, or a 22-250 as back up guns instead of the 375, 416, 470 and 500 Nitro calibers. those PHs in Africa must have it all wrong based on this logic displayed by some in this thread!

Somehow while reading my reply your brain wandered into Africa.... I was talking about mild steel, not lions tigers and bears... If you bet against a 22-250,220 Swift,22 Cheetah,etc... not out penetrating bullets from a 30-06 and the like (types of bullets being equal) through MILD STEEL you will loose money every time..

 

[Gus]

"Somehow while reading my reply your brain wandered into Africa.... I was talking about mild steel"

This is good to know type stuff that will come in handy the next time that I hunt "mild steel" bars or play Trivial Pursuit. I thought the thread was in relation to dangerous game in Africa.

 

[Evan Williams]

I Love this!!!

YES COOP i was baiting you !!!!!!

 

[Steve O]

Bullets don't compare to arrows. Period.

Animals are not steel plate. Period.

Penetration testing arrows in a foam target, which stops the arrow by friction is a bad idea. Smaller diameter arrows and slicker arrows will penetrate better...

 

[BuckSnort]

"Somehow while reading my reply your brain wandered into Africa.... I was talking about mild steel"

This is good to know type stuff that will come in handy the next time that I hunt "mild steel" bars or play Trivial Pursuit. I thought the thread was in relation to dangerous game in Africa.

Keep in mind my statements were about MILD STEEL not game..I was just trying to add to the conversation that how velocity effects penetration..Just stating facts after you argued mine... You might want to research something you don't know about before you call someone out on it...

 

[LNGBOWFLYER]

Again I disagree. It has been my experience that a 7.62mm will out penetrate the higher velocity 5.56mm bullet all day long. Whether the target is a stone and mason building, a car door, engine blocks, soft tissue, wood, you name it. There is NOTHING that the heavier slower 7.62mm did not out penetrate or out damage when compared to the lighter faster 7.62mm. And the civilian version of those two rounds are the .308 and the .223 cal rounds. Not sure what testing you have seen bucksnort that shows the .220 does more damage and out penetrates the .30-06. Because the .30-06 shoots faster than the .308. I have not done any testing. Just what I have witnessed.

 

[BuckSnort]

Again I disagree. It has been my experience that a 7.62mm will out penetrate the higher velocity 5.56mm bullet all day long. Whether the target is a stone and mason building, a car door, engine blocks, soft tissue, wood, you name it. There is NOTHING that the heavier slower 7.62mm did not out penetrate or out damage when compared to the lighter faster 7.62mm. And the civilian version of those two rounds are the .308 and the .223 cal rounds. Not sure what testing you have seen bucksnort that shows the .220 does more damage and out penetrates the .30-06. Because the .30-06 shoots faster than the .308. I have not done any testing. Just what I have witnessed.

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I haven't actually tested them , just what I have personally seen and what many others have experienced .. I definately don't argue your statement about bricks,stone or the like but as for steel the little 22 caliber pills at 3800fps+ (remember this is probably 1000 fps faster than a NATO 5.56 round) punch through it like butter..More so than a .308 caliber pills moving almost 1000fps slower.. I guess you would have to see it to believe it but a 22-250 will zip right through 5/8" mild steel plate... Again my argument was for the mild steel only..I agree with you about the other things you mentioned... You can probably find a few YouTube vids on the subject..

 

[ChadH]

Ive always put it this way, would you rather be hit by a prius doing 50 or a dump truck doing 30?

That is a fair analogy Jon Boy, but probably only if you are talking archery vs. gun. At the weight diffs and speeds we are talking about, it is more like a Prius or a Camary. Larry and Nick make good points.

 

[LNGBOWFLYER]

Bucksnort I guess when you put it that way I can see your point especially at ranges less than 100meters. Beyond that I think the smaller pill starts losing energy too fast. I know the NATO 5.56 starts running out of steam pretty quick past 300meters although it is still more than capable of "getting the job done" out to 600meters. As far as the 7.62 it starts out a lot slower but slows down a lot slower. I know it can still do work out to 1000 meters.

And this example I think can be used to demonstrate arrow weights. Just change the yardage. So let's say a 350-375 grain arrow starts out faster and may penetrate deeper out to 20yds. But at 40yds that 425-450 grain arrow is gonna end up about the same speed and since its heavier penetrate deeper.

 

[BuckSnort]

LNGBOW, I can't argue that, I think that's a valid point for sure.. I just wish I had the time and money to spend on tests like this...Some of would be interesting and fun..

 

[LNGBOWFLYER]

I hear you on that. I definately don't have the time or money to test this stuff out. It would be a lot of fun though. I just use the online calculators figure out the best setup and go from there. Ensure my FOC and spine is good and call it good from there. I'm not hunting elephants.