Penetration, a product of many factors

[4fletch]

Friction from both shaft material and diameter following a broadhead though an animal? You really feel like you can quantify that in a foam block? Sorry buddy, appreciate the effort but he test is way off base. You have so many variables and possible outliers that quit frankly it’s silly to even hint at any type of conclusive results.

Are you saying shaft friction is not a factor on a live animal? Here is that thing where people who do not like the results try to dismiss them with silly claims. There is a reason the FMJ with low shaft friction and a fair amount of the time a "low" foc is highly popular in hunters.

 

[Trial153]

Are you saying shaft friction is not a factor on a live animal? Here is that thing where people who do not like the results try to dismiss them with silly claims. There is a reason the FMJ with low shaft friction and a fair amount of the time a "low" foc is highly popular in hunters.

Who said anything about liking or not liking your results?
I am saying your results are pretty much meaningless outside your “test”, which has more holes in than a sieve.

 

[MattB]

Friction from both shaft material and diameter following a broadhead though an animal? You really feel like you can quantify that in a foam block? Sorry buddy, appreciate the effort but the test is way off base. You have so many variables and possible outliers that quit frankly it’s silly to even hint at any type of conclusive results.

Yes. Foam stops predominantly via friction on the outside of the shaft. Flesh doesn’t.

 

[Mighty Mouse]

Reduction in shaft friction is a bigger factor in pen depth than an increase in FOC when the diameter and weight of the arrows remains constant in a medium that is constant.

How are you determining the difference in shaft friction between the FMJ and Axis? I assume you're doing so based on one feeling smoother to the touch than the other. I've never seen any arrow manufacturer publish coefficient of friction or surface roughness values.

Was the point/head geometry exactly the same for both arrows? I'm guessing not since they were different weights. I've anecdotally noticed penetration differences shooting different-shaped field points (tapered, bullet, bulb, etc) into targets, and I'm sure we would all agree that broadhead shape has a major effect on penetration.

Were both arrows the same static spine? If so, their dynamic behavior (bending during the shot) will be different, which is the inherent challenge when trying to isolate the effect of FOC alone. ±50 gr of point weight probably won't majorly alter dynamic behavior, but it's conceivable that a sufficiently large change in point weight (not compensated for by also changing spine and/or re-tuning) could negatively affect arrow flight and possibly reduce penetration.

What was the sample size of your test? What were the min/max/average penetration values? Inconsistency of the target medium is bound to introduce some variation, so I'd want a large sample size if I were trying to test penetration and draw conclusions.

Your claim about friction vs. FOC may well be valid, but I don't think your test is quite as conclusive as you're presenting it to be.

 

[4fletch]

Yes. Foam stops predominantly via friction on the outside of the shaft. Flesh doesn’t.

You may want to rethink that, take a look at what happens when animals are shot with field points. An arrow that would pass through with a broadhead ends up sticking out of the animal with a fieldpoint. The broadhead opens a bigger wound channel and reduces shaft contact, friction, but it is still a large factor. That is why people moved back to aluminum, fmjs. They get smaller diameter shafts, they use an insert and head wider than the shaft.

 

[4fletch]

How are you determining the difference in shaft friction between the FMJ and Axis? I assume you're doing so based on one feeling smoother to the touch than the other. I've never seen any arrow manufacturer publish coefficient of friction or surface roughness values.

Was the point/head geometry exactly the same for both arrows? I'm guessing not since they were different weights. I've anecdotally noticed penetration differences shooting different-shaped field points (tapered, bullet, bulb, etc) into targets, and I'm sure we would all agree that broadhead shape has a major effect on penetration.

Were both arrows the same static spine? If so, their dynamic behavior (bending during the shot) will be different, which is the inherent challenge when trying to isolate the effect of FOC alone. ±50 gr of point weight probably won't majorly alter dynamic behavior, but it's conceivable that a sufficiently large change in point weight (not compensated for by also changing spine and/or re-tuning) could negatively affect arrow flight and possibly reduce penetration.

What was the sample size of your test? What were the min/max/average penetration values? Inconsistency of the target medium is bound to introduce some variation, so I'd want a large sample size if I were trying to test penetration and draw conclusions.

Your claim about friction vs. FOC may well be valid, but I don't think your test is quite as conclusive as you're presenting it to be.

Sample size, roughly 30 shots or so a week with this group over two months.
Friction difference, aluminum vs weaved bare carbon. You can feel the difference both on pulling and by running them through a gripped hand. Its significant enough a scale would read it.
Static spine, they are the same spine from the factory. I shoot through paper at about 8 feet, 12 yards or so. In flight its 125 vs 175 (as well as a third group with 150 up front. for these tests) So in flight is "Paper good"
Penn numbers. I never even bothered to put a ruler on it. It was so consistent there was no need. Outside an arrow hitting the odd soft spot the results were the same every time. FMJ 125, Axis with 175 up front. Axis with 150s and lock washer up front.
Points. In the picture the fmj has a huge 125 kudu field point that stops pen in foam. The axis has a 100g. I also used bullet points.
I actually posted this test elsewhere in greater depth. The results are repeatable to a fault. I got called out on the fmj being a 3 fletch (done to keep the weight even) and built a 4 fletch to repeat the test in case it was an issue with friction in flight or spinning. Made zero difference.
Short version i built three sets of arrows to be the same weight with three different broadheads (Turkey, deer, moose) And did this test while shooting them over a couple months. Then i chewed up one foam target doing broadhead tests for poi.
(pic arrow is a little crusty it was thrown together only for the test)
Again they do not act the same pushing weight in a canvas field bag. It is near impossible to get a fair comparison but pushing folded cloth the 150s seem to have the edge. But again, thats near impossible to say 100% and is prob close to the odds of a coin flip.

 

[Page Master]

.583 vs .545 for the light guys... I doubt very much they are the same diameter or material/shape as the momentum diff is nill.
I too can show lighter arrows going deeper than heavy arrows but there were many differences, where my example was controlled to show specifically that a slick body in the said example is "better" than an increase in foc.
Here is 486 plowing through two targets at around 271fps. This is not my first rodeo, you are going to have to provide some evidence if you want to claim contrary to what i have experienced. Remember 300fps and 400 grains did not get near what this did in two. Also a different shaft size, tapered insert...
Im not worked up. Why would you think that? Are you for some reason upset?

Ah so you're trolling. Shooting foam has zero correlation to shooting animals in terms of penetration. Foam is designed to stop arrows. All you're proving is what arrows penetrate foam better. Shoot foam then animals and provide data to back up your claims, otherwise it's just another post on rokslide from someone who thinks they know it all.

 

[4fletch]

Ah so you're trolling. Shooting foam has zero correlation to shooting animals in terms of penetration. Foam is designed to stop arrows. All you're proving is what arrows penetrate foam better. Shoot foam then animals and provide data to back up your claims, otherwise it's just another post on rokslide from someone who thinks they know it all.

"All you are doing is showing shaft material and makeup is a more important factor in overcoming friction placed on the shaft than foc"
Exactly. Glad you understand. I hope nobody scares you today with any of that pesky math garbage.

 

[wayoh22]

Watch out FOC, the coefficient of friction is about to take over...

 

[Page Master]

"All you are doing is showing shaft material and makeup is a more important factor in overcoming friction placed on the shaft than foc"
Exactly. Glad you understand. I hope nobody scares you today with any of that pesky math garbage.

I'm a math major in a math centric field of work that shoots more than 30 arrows a week for a couple months then decides he is going to form an incorrect opinion and tell anyone who disagrees to ''prove him wrong'' despite providing zero evidence other than subjective statements.

Good day sir.

 

[Rob5589]

Watch out FOC, the coefficient of friction is about to take over...

You're gonna have to call it something else. FOC, COF, are way too similar and confusing. Maybe a combination; the COFOCF. Just spitballing here so...

 

[KyleR1985]

Foam doesn’t bleed and lubricate arrows. Neither do animals shot with field points.

the only conclusion you can draw from your activities is “less friction will result in more penetration, all else being equal.” The problem is that all else is not equal in your “testing”, or the real world. You don’t have the time, money, nor training/skill set to perform a test that will be useful to anyone.

if you’d like to say “my opinion is that friction on impact is an important factor in penetration” I don’t think anyone would bat an eye. I’d counter with “if you hit an animal in the parts that bleed a lot, the difference in shaft diameter and finish will correlate much weaker with total penetration, than those variables would in a dry consistent medium.”

 

[wayoh22]

You're gonna have to call it something else. FOC, COF, are way too similar and confusing. Maybe a combination; the COFOCF. Just spitballing here so...

Just call me Ranch Friction and it'll all be ok, everyone can start drinking the new koolaid.

 

[Beendare]

Friction from both shaft material and diameter following a broadhead though an animal? You really feel like you can quantify that in a foam block? Sorry buddy, appreciate the effort but the test is way off base. You have so many variables and possible outliers that quite frankly it’s silly to even hint at any type of conclusive results.

.

 

[Page Master]

This^

OP, we have all seen the many “tests”….this is not the first rodeo for many of us that you assume.

How is it that I’m blowing through many species with my measly 48# recurve setup But then on foam I get only avg performance?

The KE on my setup is frankly embarrassing- grin …but I find bloody arrow after arrow on the other side of game. In my experience, Shooting an arrow into foam has almost Zero correlation to shots on game….sorry to burst the Ranch Ferry bubble but these clowns are just guys on the internet trying to fool their fan base.

Chuck Adams debunked foam testing 3 decades ago…many here were probably too young.


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I still don't know what OP is trying to tell us to be honest.

 

[Trial153]

I still don't know what OP is trying to tell us to be honest.

The FMJ arrows are the best because they a slippery

 

[Page Master]

The FMJ arrows are the best because they a slippery

Better start dipping my black eagles in KY. Maybe OP can lend me some.

 

[4fletch]

This^

OP, we have all seen the many “tests”….this is not the first rodeo for many of us that you assume.

How is it that I’m blowing through many species with my measly 48# recurve setup But then on foam I get only avg performance?

The KE on my setup is frankly embarrassing- grin …but I find bloody arrow after arrow on the other side of game. In my experience, Shooting an arrow into foam has almost Zero correlation to shots on game….sorry to burst the Ranch Ferry bubble but these clowns are just guys on the internet trying to fool their fan base.

Chuck Adams debunked foam testing 3 decades ago…many here were probably too young.


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KE is irrelevant with arrows as a killing metric. Velocity x velocity x mass. It puts a premium in velocity and an arrow does not kill by energy dump. An arrow kills by cutting that leads to blood loss. To do so it has to overcome friction. Of the head, shaft, flight, energy loss in flex, noodling in the game. I know guys who can throw a curve that will have you kissing dirt. They can not begin to explain all the things going on to make it happen. Overcoming friction is an issue. The issue. You do not have to see it for it to be.

 

[KyleR1985]

Well I ain’t never seen no plants growin outta no toilet.

 

[MattB]

You may want to rethink that, take a look at what happens when animals are shot with field points. An arrow that would pass through with a broadhead ends up sticking out of the animal with a fieldpoint. The broadhead opens a bigger wound channel and reduces shaft contact, friction, but it is still a large factor. That is why people moved back to aluminum, fmjs. They get smaller diameter shafts, they use an insert and head wider than the shaft.

No need, been doing this long enough to know better.