Pondering Penetration ??????

[George D. Stout]

"Imagine you are just shooting a broadhead, and the arrow shaft and fletching is there to help the broadhead get to the target straight. All that matters is that the broadhead gets through, not the shaft."  

Well...yeah, but the broadhead won't get there, nor will it go through, without the rest of the arrow 8^).  It's weight distribution we're talking about here, and how much goes where within the confines of the arrow itself.

What we are really dealing with here is, "degrees of better."   I have no doubt that there is substance to the heavy front of center, and that it would even be more conspicuous when hunting very large game...maybe 8^).  But when we are deer hunting, what has worked very well, will still work very well.

So...he said...it is all a matter of personal choice at this juncture.  I have some 2314 aluminums with standard aluminum inserts, 125 grain broadhead adaptors, and Bear Razorheads attached.  They fly very well and I still have a decent point on with my bow.  I expect that they will penetrate very well on a relatively, narrow bodied whitetail, and I must say they pack a good whallop with a steel blunt on the end 8^).
The real test will come on squirrels with a steel blunt. Now those critters are really tough.

 

[John3]

I love the trad gang. Superb posts, George.

Oh yeah, give me an heavy arrow everytime with a bit more weight up front...


JDS III

[katman]

Let's not forget the higher foc arrow will be more stable in flight due to the longer lever arm of the fletching, thus aiding penetration with less wobble on a poor release.

"But when we are deer hunting, what has worked very well, will still work very well." But I have had times when penetration was not what I expected on whitetail with normal foc, would efoc worked? No way to know since we can not turn back time. So I switched to efoc. Time will tell if it meets my expectations over the long haul, but you are correct that the only proof would be repeatable scientific studies. Who has the time and $ for that? It is just that some of us wish to maximize our setup using current info available, that does not mean that normal foc won't work, but back to the original post the efoc would work better imo.

[Don Stokes]

A couple of points to consider:

When you select a stiffer shaft, and then add extra point weight to make it shoot properly, what you are really doing is making the stiff shaft bend more to overcome the inertia of the heavy point. The end result is that the stiffer shaft bends as much as the lighter spined shaft. Otherwise, it wouldn't tune properly. I'm not sure that everybody understands that.

The most extreme case of FOC can be illustrated by a broadhead with a string tied to it. If you could somehow propel it at arrow speed, penetration would be questionable, since the broadhead would not be stable as it penetrated an animal, because of the considerable variability in the density of the tissue it was penetrating. The function of the shaft is to guide the head, whether it is in the air or inside an animal. Differences in the flexibility of the shaft at the point of impact are immaterial to the reality of pushing a sharp head through skin, muscle, organs, etc. There's so much variability in this equation that the influence of a single variable (FOC) is not likely to be detectable in reality.

Penetration is more likely to be determined by the alignment of the arrow shaft with the point when it hits the target, than the distribution of weight between the head and the shaft. An arrow that's wobbling when it hits won't penetrate well, regardless of FOC. One that's flying straight WILL penetrate well, also regardless of FOC. There may be some degree of difference, but I just can't believe that it's enough to matter significantly in the big picture. It's easy to get balled up in theoretical details.

As long as the arrow is flying right, the best way to increase penetration is to increase total arrow weight. Whether this is accomplished by a heavier shaft or a heavier head or both, the end result is the same. That much we know to be fact, based on real world evidence.

[Daddy Bear]

I'm not sure I followed your post correctly. But, be it a bullet or be it an arrow, if you have too much weight distributed to the rear, this extra rear weight will induce yaw as soon as the forward head meets resistance. The tail end will then attempt to pass the head end. With a bullet, it would tumble. With an arrow, you'll have wasted momentum and energy behind the head because some of the forces will be directed in the direction of the yaw. Having weight distributed FOC reduces this tendancy to yaw and therefore maximizes the momentum and energy directly behind the head going straight forward.

Any degree of weight %FOC is intended for this purpose so that the arrow is stable in flight and maintains straight penetration when meeting resistance. Having an arrow manufactured from tapered carbon allows one to maximize this weight %FOC which makes it difficult for a tuned arrow to do anything BUT straighten out and fly straight. This makes it very difficult for the tail end of the shaft to yaw when the head meets resistance which results in maximizing the momentum and energy in a straight line directly behind the head.

There is nothing new to this logic as Badminton has been played since early times in ancient Greece:^) What is new is that current tapered carbon shafts make it rather simple to obtain higher %FOC without all the work required as when using wood.

[Biggie Hoffman]

Dang it George, that "degrees of better" line killed the whole thread for me  :-(

[Jason R. Wesbrock]

Originally posted by George D. Stout:
Are you suggesting that coconuts migrate?

Not at all. They could be carried.  

[Don Stokes]

Daddy Bear, I agree with you, but in the case of an arrow with more or less FOC, you don't really have the rear weighted in the arrow with less FOC. The weight of the shaft is equally distributed from the nock to the point, with the insignificant exception of the feathers, which weigh only a few grains. It's not like you have weights on both ends of a weightless shaft.

The yaw you refer to becomes evident only if lateral forces come into play, which may not happen at all if the arrow is flying straight when it hits. If the weight is all perfectly aligned with the shaft at impact, it will go straight in. One could conceivably argue that a heavier shaft in alignment would have better resistance to lateral forces during penetration due to higher momentum, and lead to improved penetration.

Like I said, it's easy to get balled up in the details.  

[ChuckC]

Don  from my point of view, the stiffer spine / heavier tip vs lighter spine / lighter tip theory is right on when you shoot, however when the arrow hits, the weight forward is taken out of the equation and we simply have stiff  and stiffer to deal with.

Most of my arrows pass right thru a deer.  (or, right past them.. over, under, around).  as was stated already  What has worked well in the past will probably continue to work quite well.

I truly understand the theory of planning for what goes wrong, but that can be extended ad nauseum.   A compound is better,   a gun is better yet,  where do we stop.   I use a long bow for a reason,  what ever that reason may be.

I intentionally stack the odds against me.  Its just what is.
Chuck

[Bill Carlsen]

Hmmmm! All I know is that my arrows with high FOC out penetrate the ones with lower FOC. This has been particularly true for my wife who shoots a bow in the mid forties at her draw length and shoots a 500 grain arrow with 200-225 grains up front. She gets great penetration with that set up...and as I indicated, after shooting for over 50 years I have never had the penetration I get with high FOC than before I tried it. Hunting from treestands, in particular, is where I see the biggest difference. If I went with a lower FOC I would be shooting a lighter spined shaft which would seem to me to be more "flexible" at impact resulting in less penetration than I would otherwise get with the stiffer shaft carrying a heavier head. I'm not trying to argue, I don't think...my experience is what it is and high FOC works better for me and for my wife.

[katman]

"If the weight is all perfectly aligned with the shaft at impact"
How often is perfect alignment achieved? I would guess not very often (poor release, wind, hitting a rib etc) so the arrow will bend on impact, the higher foc arrow being 'statically' stiffer will resist the bend more and waste less energy causing deeper penetration.

[Don Stokes]

Bill, if it works better, that's the important thing. Theories are fun, but reality is what counts. I've learned to never say always or never.  

[Don Stokes]

katman, I do all this tuning and practicing to be pretty darned sure that my arrow will be flying straight when it hits.     If it's not, I know it won't penetrate well, no matter how much it weighs or how the weight is distributed. That's the bottom line for me.

[bowdog1]

Thanks everyone. Don Stokes analogy of 600 gr BH on a string traveling at 180 fps would not have much penetration, therefore it seems that arrow weight is very important. Seems that 500 gr shaft @ 180 fps would push 100 gr head deeper into ground. Try shooting 600 gr arrows straight up (wearing bullet-proof hardhat), one 150 head/450 shaft vs 250 head/350 shaft. Each arrow would have stabilized to its maximum and the heavier shaft should win???????

[Dave Bulla]

Don, you explain things quite nicely and I totally agree.

Reading this post I kept thinking about the old demo's they used to show in some magazines where a hi velocity bullet was fired into a bucket full of sand and didn't exit the other side then an arrow was shot into it and it either went clear through or if it stopped, it still penetrated out the far side.

Now part of that is due to a bullet expanding but a lot of it has to do with the arrow shaft pushing from behind.  The bullet would be close to Don's example of a broadhead with a string behind it only it's even more extreme like a broadhead flying by itself.

In my mind, balance and moderation take the day.  It's like speed versus forgiveness.  Sure moderation may not give you the "most" but it is consistent and predictable.  If a balance of weight between head and shaft is sufficient, why push the envelope at all?  How far through a deer do you need to shoot to kill it?  tune what you got to it's optimum performance and go hunting.

[Don Stokes]

Bowdog, you might want an arrow-proof hardhat- remember that bucket of sand??  

[fyrfyter43]

Originally posted by bowdog1:
Don Stokes analogy of 600 gr BH on a string traveling at 180 fps would not have much penetration

That's just 'cuz it would be awfully hard to get a string arrow tuned to any of our bows.  

[fyrfyter43]

Seriously, the more weight you have to the rear of an arrow, the more the shaft will flex on impact, decreasing penetration.

[b.glass]

Somebody get me a bucket of sand!!!

[George D. Stout]

It irritates people when they find out they may not have the final solution 8^).  

Hey Mom....you're not gonna put that sand in your arrows are ya?