Trad Gang
Main Boards => PowWow => Topic started by: NorthShoreLB on January 04, 2008, 07:17:00 PM
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Wanderful piece he wrote on the latest TBM, wish more people will take in consideration his studies about the heavy arrow advantage.
...Now there's something that I quite don't understand,...if 2 arrows are of the same overall weight and both fly the same, why would the one with more FOC penetrate better ?
I'm not going against this being one that loves extreme FOC, but I'd like to understand why, maybe some of you technical brain people can explain it to me.
Thanks
Manny
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Not sure but may be the one with a high FOC will begin penetrating immediately upon impact and the one with less will have to wait for the arrow shaft to flex a bit before starting to penetrate. Hope that makes sense.
Rob
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I it because the majority of the weight is closer to the point so there is less shaft to deflect on impact with the target.
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The shaft with extreme FOC will flex less upon impact. Arrow flex upon impact causes drag. Extreme FOC arrows will have less flex and less drag leaving more energy to penetrate.
Jason
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That makes sense, thanks !!!
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man that's really splitting hairs.....
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Actually Biggie that's what I used to think, too. But Bob Morrison described a test to me in which he took the same bow and the same arrows and the same BH, but in one arrow he put a heavy insert behind the BH and in the other he added weight inside the shaft. Both arrows weighed exactly the same amount, were the same shaft and the same BH - just one had high FOC and the other carried the weight through its entire length. He then shot both arrows 12 times each into 7/8" marine plywood. All 12 shots with the "normal" FOC arrow produced a bounce-off. All 12 shots with the high FOC arrow stuck into the plywood with (as I recall) 3 or 4 having the BH protruding out the back side of the plywood panel. Bob would be the first to admit that there are still uncertainties in his test which were impossible to resolve. But the results speak pretty strongly to the benefits of not having the tail end of the arrow paradoxing when it strikes the game we're trying to penetrate.
I thought it was an interesting experiment with very interesting results.
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yeah I've heard of test like that but I don't think it proves anything. Plywood is a laminated hard suface, it has give to it, bounce etc,
So many test nowadays are flawed. Especially allot of the broadhead tests. Most broadhead destruction is "after the fact" and means little as far as a clean kill. I mean anyone can destroy a broadhead so what? Know what I mean?
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Unless I am mistaken the tests described by John were repeated by DR. Ashby on animals with similar results. Unfortunately it is difficult to achieve high FOC with wood like you can with carbon and aluminum cause it is so hard to get that stiff a woodie.
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Yes, the extra penetration is a result of reduced shaft-flex at impact and during penetration.
The Prologue to the 2007 Updates gives a more complete explination of the 'why and how' Extreme FOC arrows achieve this reducion in shaft flex, and resultant shaft-drag. However, there also is a bit more to understanding how important a penetration factor Extreme FOC is, and how to achieving the most from its conserved energy (and, yes, energy applies here).
Less shaft-flex means conserved arrow-energy, which also means more retained arrow force (momentum).
The more efficientently your entire arrow setup is able to use (apply) the conserved energy and arrow force (momentum), the longer the TIME fator of the arrow's IMPULSE OF FORCE will be.
Against any given tissue resistance, it is the IMPULSE OF FORCE that determines the final amount of penetration.
The formula for the impulse of force is the net arrow force (momentum) applied during penetration MULTIPLIED by the the time period that the force is applied.
Since the ADDITIONAL impulse (and resulting extra penetration) that results from less shaft flex is a PRODUCT derived from MULTIPLYING the conserved force (the 'extra retained momentum') by the ENTIRE time period of the impulse, the penetration increase will be a far greater than suggested solely by the amount of reduced-resistance (or retained arrow force) that results from reducing the shaft flex and drag.
On all except a total abrupt-stop impact, the extra retained momentum also extends the TIME FACTOR of the impulse of force. This further contributes a geometrical increase to the arrow's resulting penetration.
Extreme FOC's total penetration increase is IN FACT far greater than the SUM of the force saved and the increase in the time of impulse; it is the product of them. Each MATHEMATICALLY MULTIPLIES the other to derive the outcome penetration. Understanding this is the key requirement to understanding arrow penetration; and knowing how your arrow's setup impacts its termianl performance.
The Part 4 2007 Update will have penetration results from two sets of arrows as precisely matching in all dimensions except FOC as I could achieve - including flawless flight - from a 54# straight-end longbow. They are as startling as those John relates above - perhaps even more so.
There will also be a comparison of penetration results from this 54# bow's Extreme FOC arrows and 'normal and high' FOC arrows from both the 70# and 82# longbows used in testing. Only 'comparable shot' data is used; for shot range, shooting angle, impact angle and location, and animal size. For these 'matching shots', comparison is made against 'all single blade' broadheads and those with the same BH as the lighter bow's Extreme FOC arrows. There will also be a comparison of Extreme FOC arrows from each of the three bows.
It's fascinating stuff and, bottom line, Extreme FOC makes a very, very significant contribution to arrow penetration when everything else about the arrows matches exactly. Exactly how much difference does it make? You'll have to read Part 4 and 5 Updates!
Ed
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Originally posted by Biggie Hoffman:
man that's really splitting hairs.....
Biggie - lets us get deeper in the dirt ;)
Steve
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One aspect of high FOC that I don't quite have straight in my head is that a high FOC doesn't equate to super heavy overall arrow weight, does it? One can acheive the same high FOC using a 150gr point on a light shaft as using a 250gr point on a heavier shaft. Of course you'd have to play around with different spined shafts given the difference in point weights.
I guess what I'm getting at is I see alot of threads where guys give positive feedback concerning high FOC but it always seems they also have heavy arrows as well (200 or 250 gr points). So to utilize the advantage of high FOC do you also need heavy overall arrow weight or can one get the advantages of high FOC by coming up with a point/shaft combo that keeps overall arrow weight a little more moderate?
Not trying to debate heavy versus light, just wondering if regardless of overall arrow weight one should try and acheive a high FOC (assuming one believes there are advantagwes to high FOC)..
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Stephen, you are absolutely correct. In fact, using penetration averages, all the data indicates that extreme FOC's DEGREE of penetration gain - percentage wise - is greater the lighter the arrow becomes and the lower the arrow's force becomes.
However, that can be misleading. DO NOT confuse DEGREE of BENEFIT with the TOTAL AMOUNT of benefit. Higher mass arrows have higher penetration to begin with, so it takes more inches-of-penetration-increase to represent the same percentage of gain that a low mass arrow attains.
Also, you need to consider the number of penetration barriers encountered (ie: just entrance-side skin and ribs, or both entrance and exit-side ribs/skin) and the limits of measurable penetration (penetration is measured as depth of the wound channel through tissues, and penetration beyond that is not accurately measurable). In the buffalo testing, on all shots from reasonable shooting angles, an exceedingly high portion of all structurally-intact Extreme FOC arrows having a mass-weight above the heavy bone threshold fully traversed the thorax to reach the off-side ribs.
Arrow mass becomes a more critical factor on heavy bone impact, and the amount of FOC has not demonstrated any effect on the heavy bone threshold.
All that notwithstanding, Extreme FOC is decidedly a desirable penetration-enhancing feature on arrows of lighter mass; greatly enhancing soft tissue and light-bone penetration.
Ed
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Good reading :thumbsup:
...since it's hard to achieve high FOC on woodies, (unless we start using those alluminum arrow adapters, ....than we can get up to 375gr point ,..just got some and I'll try them soon)
I assume than, from following this studies, that would be better using alluminum or carbon shafts.
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NSLB - At Extreme FOC levels (above 19%), I've found it very difficult to get the quality of flight I want when using aluminun shafting. Carbon shafting is much easier to get great Extreme FOC flight with, at least in my experience.
I think the difference has to do with carbon's flexional characteristics - and that may also be one reason carbon-fiber poles replaced both metal and fiberglass ones in Pole Vaulting.
Think about the amount of weight FOC (and how much it shifts) on a vaulting pole during the verious stages of the vault - and the fast recovery the carbon-fiber pole makes from a state of extreme flexion!
Ed
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I have never read through a whole report so maybe I'm missing something. I don't ever think I've seen actual picture results and I am still unsure as to how the data is recorded. What I mean by that is how does Dr. Ed know how much has penetrated? He says, "In Buffalo testing..." is he actually shooting at a whole live Buffalo? Is it a side of hanging Buffalo or maybe bones encased in ballistic gelatin with Buffalo hide over it? Another question I have is how do traditional arrow penetration compare to compound arrow penetration with BH or mechanical BH's flying at 280+ fps?
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He shoots fresh killed buffs. All that matters here is how traditional tackle works. Compound comparisons are outside the scope of this forum. Lots of good stuff in the reports if you do read them. Even for long time trad shooters.
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....hmmm, so Ed you'll be suggesting to shoot carbons to get best results, any particular brand?
I'm getting good flight out of my 71# Hill (without cut in arrow pass) with 27 1/2" BOP 2117 legacys and 430gr up front.
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I understand that the compound comparisons may be outside the scope of this forum, but I think it would be nice to see what's happening on the opposite side of the spectrum as a comparison. Lighter, less FOC etc. If we're are getting down to the technical science and we're talking performance with penetration, I like to weigh the scales. Dr. Ed seems to be the only one writing up the reports, so pretty much whatever he says is gold. Once upon a time the world was flat. Coming from a world of studying ballistics on long guns and pistols, I'm trying to adjust to the world of trad and get on the same page as Dr. Ed. I think I'll take my time and read through all the reports and look for answers to my questions there.
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Reynaldo, seek and ye shall find.
The study's testing has included bows of all types; something necessary to reach the stratospheric KE levels (of the bow world). Testing of the KE/Momentum relationship to outcome penetration in tissues with normal and high FOC arrows has involved IMPACT KE levels up to 94 foot pounds. That information is among the study updates and associated articles to be found here on TradGang, along with comparisons against the terminal tissue performance of both normal/high FOC and Extreme FOC arrows from traditional bows.
In just the last couple of months, I've had offers from a top wheel-bow shooter and hunter and a couple of light draw-weight trad bow shooters to further investigate (on whitetails and hogs) the Extreme FOC effect at the higher impact KE/momentum levels; and this is greatly appreciated. Very similar arrows are being used by each.
I'm also seeking a correlation of the penetration ratios between higher-mass (above threshold value) Extreme FOC arrows from lower draw weight traditional bows with that obtainable with lower mass (below threshold) Extreme FOC arrows at higher velocity; and trying to ascertain if Extreme FOC has any significant demonstrable effect on the heavy bone threshold, as velocity is increased.
It is also likely this testing will provide more insight into the relative penetration-importance of the time of impulse, as opposed to the increasing the force component of the impulse.
Only time and the results will be able to provide an accurate answer.
Ed
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The proof's in the pudding. In 42 years of practical bowhunting experience, a heavy arrow, a sharp broadhead and a good shot works everytime.
All this other stuff may be interesting to some but in the end, it won't change the physics of archery.
No disrespect meant towards "Dr" Ed
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when i grow up i hope to be as good a shot as you biggie ! hopefully i can hit everything perfectly evertime so i can watch it fall. until then i want to eliminate as much of the "oh crap!" possibilities as i can.
for instance last week i shot a doe from the ground at 5 yards, i aimed at her knuckle and i hit her in the top of the shoulder blade, threw the top of her lung, past the spinal cord and into the top of the other lung.
i got about 4 inches of soild bone penetration and severl inches of muscle tissue penetration with the grizzle head, if i had been using right fletched arrows with the grizzly's i probably would have gotten a passthrew. would a snuffer or razorcap have gotten that much penetration, i don't know, but i have watched a snuffer stopped cold, actually bounce of a does shoulder blade, so probably not.
but the morale is that even thou we make a perfect shot we can end up with a bad hit and it sometimes takes every little bit to ensure a clean kill.
sry no pictures i am still kicking myself for not taking any, i was in a hurry to skin her and get her on ice, we had to go look for another deer a friend had on the ground. we were unsuccessful in finding the other deer.
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"a heavy arrow, a sharp broadhead and a good shot works everytime."
So what part of this statement do you disagree with?
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Originally posted by Biggie Hoffman:
All this other stuff may be interesting to some but in the end, it won't change the physics of archery.
Dr Ed and others are not trying to change anything, but are working to learn and share so that we can all understand better how it all works.
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Biggie,
watch it now, you are treading on a dangerously slippery slope... If you don't agree, fine, but keep it civil please. "Dr." Ed has a PhD, so he is, in fact, a Dr, and not a "DR",.... as well as a few other choice pieces of your statements... just please keep it civil, no one is saying you are wrong or that your experiences aren't sound.
Mike
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I've gone through all available reports. I haven't read the part 4 update. Is that what's in the TBM mag? Very interesting and informative. Though I question whether extreme FOC and IF have any relevance when hunting deer or bear or anything that is not heavy and thick like buffalo. Like Biggie says, heavy arrow and sharp well placed broad head. If I ever hunt big game here in the states or abroad, I will strongly take this research into consideration when choosing the appropriate gear.
I am going to have to hunt down the next update. I'm curious to know the length of footing you were using Dr Ed. I would also like to know what the difference would be using an external footing of comparable length to compensate for the insert vice the internal footing. Reading about shaft breakage peaked my curiosity. A while ago (using GT traditional 3555, and 5575) I deliberately shot a few arrows at a steel beam to visually see the aftermath of doing so. With a 15% FOC on both types of shafts I had the 3555 split and fray 5" up the shaft looking like a cartoon cigar exploding. With the 5575 shafts I had one showing a hairline split on the outer lamination going up 1.5". However it was still bonded to the lamination beneath it and the insert was still intact. The other 5575 did not show any breakage to the naked eye, but the insert did eject. I'm sure if I were to use some penetrating fluid and UV light I might find different results. The steel beam did not give and I imagine the flesh and bone would give dramatically compared to the steel beam. So I'm wondering why the shafts would be prone to breaking going into buffalo after conducting my own durability tests on metal. The only thing I can imagine is that the portion of the shaft that has not penetrated is flexing at the point of penetration beyond it's limitations.
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nothing, i agree with you biggie, a heavy arrow, sharp broadhead and a good hit will do it everytime,
but a sharp broadhead and a heavy arrow wont do much if the animal moves, or you hit it in the wrong spot.
i don't think you understand where we are coming from biggie, i totally agree with you that a heavy arrow and a sharp broadhead is great for those perfect hits, or just good hits, but when everything doesn't go my way i want to have everybit of penetration and bone busting power i can get, to kill the animal.
i have never had a problem losing and animal hit threw the lungs/heart area with a 2, 3 or 4 blade head, but i have lost game because i didn't get enough penetration. i don't think anyone would argue a 3 or 4 blade broadhead will out penetrate a solid 2 blade.
so why use the head that is designed to make the great hits awesome instead of the head that makes the less than perfect hits good enough to kill game ?
i am not nocking the 3 or 4 blade broadheads ability to kill game, because they will kill game if hit perfect, but noone is perfect and a perfect shot doesn't guarrentee a perfect hit.
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" but a sharp broadhead and a heavy arrow wont do much if the animal moves, or you hit it in the wrong spot."
I disagree, that's one of the reasons we use heavy arrows and sharp heads.
A light arrow and a dull head might not do much though.
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lol terry
let me rephrase that some
a sharp broadhead and a heavy arrow wont guarrentee a kill if the animal moves.
i give up, i am not going to respond to anymore 2 blade debates, it is clear that after 40 years of hunting experinece and how ever many years of experience that the everyone else has i am not going to change anyones mind on what they choose to hunt with.
and it may never happend and i doubt we would hear about it if it did but i hope that you don't loose any animal with a 3 blade head because of poor penetration.
happy hunting ; )
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"a sharp broadhead and a heavy arrow wont guarrentee a kill if the animal moves."
Can you tell me what type of head and arrow WILL guarantee a kill?...If so, I'll gladly change my mind!!!! :D
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Interesting dialog. I like the research Dr Ashby is doing but some things seem unanswered (and this is all relative to deer as thats where my experience is.) As with all research, practical application often yields some unforeseen and possibly negative side effects. Here are some things to ponder that I don't have concrete answers for,maybe some of you can provide factual answers:
1-I think Ashby's research shows increased penetration leads to increased lethality.
2- But, does that lead to increased recovery rates? Does going through one shoulder ensure an exit wound? If not will the result be more dead unrecovered deer due to poor blood trails? Many shoulder shot deer survive (and yes many do not), I know of one I shot that was taken a year later that appeared healthy.
3- What % of the unrecovered deer are shoulder/bone hits and what% are gut shot? I don't know if the answer is out there but if there are more gut shot deer than shoulder shot then maybe more emphasis could be placed on improving that recovery rate.
4- Would a 3 blade like a Woodsman or Snuffer improve the rate of recovery for gut shot deer? If that answer is yes(big if) and there are more gut shot unrecovered deer than shoulder/bone shot does that make a 3 or 4 blade the better bowhunting head?
5- Is there a significant difference in pass through rates between 2-3-4 blade heads on gut shot deer?
6- Do you get better blood trails with 3-4 blade heads vs 2 blade heads?
7- Ultimately (and again, relative to deer,) which broadhead gives you the best overall chance of recovering your deer, regardless of the hit.
8-If all this sounds like late night ramblings, it is, Besides it's hard to concentrate with the OSU/LSU game on
For the record, I shoot 2 blade Zwickeys and wood arrows ranging between 500 and 600 grains, depending on the wood. My bow is a 54 pound Robertson longbow and I have no clue how fast it is or isn't, it shoots where I point it. I refuse to go to a heavier bow to achieve a certain level of KE especially if it results in me being less accurate.
I'm sure all the experts out there will make me to be an idiot but maybe I'll learn something. Fire away.
DonD
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Way back when, I remember everyone was weighting their carbon arrows with everything from pepper to weed eater line.
I had problems with arrow flight and getting my spine right and eventually wound up putting about 250 grains on the front end of my arrow.
I posted here and most everyone shot me down as FOC was all the rage even though I get perfect bare shaft flight.
Then about 6 months later Morrison is doing something called "Front Loading" to his arrows and every jumps on the band wagon. I love it. :)
I like my 220 grain Muzzy Phantoms. The first half of the blade enters like a two blade giving enough pentration to sever a spinal column or split bone then the bleeder blades create a bigger hole. I think it is a good compromise between a three blade that enters as such and a two blade that does not has as much cutting surface. The ferrele is stainless which removes a weak point that Dr. Ashby speaks about in his article.
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I love that pudding too Biggie........it's the best..bd
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I checked on 3 Rivers for the Grizzly 190s. Judging by the picture on the website, the Grizzly that they are offering is similar to the modified version of the Grizzly that Dr. Ashby describes in his latest interview in TBM. Is this a fair approximation of his ideal BH?
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We all have to live with the results of our equipment choices.
For myself, now that I have read Ashby's report I won't go out bow hunting unless I've addressed the majority of the items presented in the TBM article. If a bad shot happened and I didn't get the penetration I wanted and I didn't recover the deer I would be kicking myself knowing I had information in front of me that may have changed the outcome.
Now if I chose to hunt a deer with a flint head I would do so for different reasons. I would go into it knowing that the stone points may not have the bone splitting capabilities of a modern steel broadhead and accept what may happen. That does not mean I would take bad shots or good shots in bad circumstances. The idea of hunting with stone points is a historical one giving me a link to my ancestors.
I don't believe Dr. Ashby is splitting hairs, he is simply presenting the results from his unbiased study. He even incorporated the extreme FOC idea to his study after someone else indicated it improved penetration. If he was biased he wouldn't of incorporated it. He is in search of the truth. If you read the article, the cumulative numbers in the gains in penetration are not trivial. If one chooses to stay with their tackle after reading the article because they are happy with it, that's completely fine. I however, want to have as many odds stacked in my favor and will do my best to build the best arrow I can (whether it's carbon or wood) to hunt with. After reading the article I don't believe using a compound stacks the odd in my favor any more than using my longbow.
Jason
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By follow Ashby's advice as closely as I can, my last two elk, a cow and a 5x5 bull, both went down within sight after full pass-through shots, ribs and all -- 12 and 30 yards, respectively -- making blood trailing superfluous. On no elk I ever killed with a bow before that (a quarter-century's worth), while using lighter (around 550 usually) shafts and multi-blade heads did I ever get full penetration or have an elk die within sight ... though I did call one back one time to die in front of me. In my experience, the Ashby formula works best even with considerably lighter bows than I was using with the pre-Ashby arrow setups. Darned if I can understand why anyone would get angry because one of our own, who happens to be a scientist and a good one, is so selflessly trying to make our hunts more humane and successful. Dave
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Dave - people only get a little twisted when others are using what they may consider anecdotal observations to strongly suggest that those not immediately modifying their equipment are somehow doing a dis service to the animal, hunting or ethics.
This may not be their intention, but it is the way it comes across from many and very stronly from some.
There are pluses and minus to all setups - it is up to the individual to find the balance that they are comfortable with.
Steve