richa3md

Well I was in now way trying to be offensive if perhaps I came off that way. I tend to be blunt in real life and if that transcends to this forum I apologize in advance. I may have gone off the topic but I thought this was my chance to get my opinion of my chest. Again I did not want that to come off as being aggressive or offensive I was just giving my opinion on the whole thing.
Thanks,
Cheers!!!!

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09' PSE Super Short 29 in and 72.5# and 125 gr G5 Striker Magnum!!!

richa3md

But I do get excited when some new technologically enhanced broadhead comes to the market because I love to see successful designs come to the table.

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09' PSE Super Short 29 in and 72.5# and 125 gr G5 Striker Magnum!!!

Booner

hahahahahahahahahahahahaha!

Standing Bear

Matthew, Richa3md - I believe that good things happen to good people and you two are outstanding ambassadors to us all.

Remember, its not because you have a discussion with someone that you have to agree with everything the other person says, that's what learning is all about. Matthew is an encyclopedia of knowledge and I am always overwhelmed with the amount of information generated by him but you know what, I'm happy to know him, just like everyone on this site. Mark, you do things for your fellow bowhunters, your tests are simply awesome.

Has anyone ever heard about the orange story? Well you see, there is this Chef and a hungry guy and they are both sitting at a table. On that table is a single orange, hummmmm says the Chef, "You know I could use that orange", the hungry guy said," Me too, so what do we do?". Because both of them were thinking about what they wanted, they decided to split the orange in two and they both had a piece of that orange.

What could have been done different you might think.......if they would have continued their discussion, they would hvae found out that the Chef only wanted the orange for the orange peel of which he needed for his recipe and the hungry guy, well, he was just hungry so he wanted to eat it.

If they would have done that, they would have both had the whole orange to themselves. Pretty awesome I say. Another reason why I love this site and people like Matthew and Mark because in the end, they both took the time to understand each other and, well, they both had the orange to themselves.

Food for thought........

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Authorized Athens Archery Dealer, Athens Factory Staff Shooter Swhacker Pro Staff

wyetterp

Here's the best info you can find on the explanation & benefits of the single
bevel.

http://www.alaskabowhunting.com/PR/S...Broadheads.pdf

But ye be warned, Dr Ashby's findings can create obsessive behavior & spark
a quest in search of the perfect harvest!

__________________
Experience is something you don't get until just after you need it.

Arrowds

Okay...I don't mean to get all "Physics" on ya'll...but this is a good chance to delve a bit deeper into what I do and how I reason out such efforts in descriptions which provide plausible sounding conclusions...but upon closer inspection don't quite add up when the math is put to the paper or demonstrate performance claims in the field despite serious, consistent test efforts.
But still...keep this always foremost in mind...they both kill critters! Just try to keep an open mind with respect to that...and we'll jump off the cliff and learn a few things when physics is reviewed in more detail with no emotional attachment to the effort beyond enjoyment in discovery of scientific fact.

The law of conservation of energy is an empirical law of physics. It states that the total amount of energy in an isolated system (Arrow/broadhead now in flight right at moment of impact) remains constant over time (is said to be conserved over time). A consequence of this law is that energy can neither be created nor destroyed: it can only be transformed from one state to another. In this instance...there is 100% of all the energy transferred into an animal should the arrow stop within the body of the animal...or as often is the case...some is transferred but not all when a complete pass thru is achieved ( < 100% ). This is due to "Friction". We will make an assumption that resistance to forward momentum is equal for both style broadheads...meaning they both experience the same value of frictional force in direct opposition to forward momentum.


Example for tweeking your thought process a bit....it takes "energy" to maintain rotational motion. Where does this energy come from? Initially in his article he claims that this rotation improves penetration due to forcing the "Meat" away from contacting the shaft thereby reducing friction on the shaft...okay...sounds good so far for a given depth of penetration in a constant medium and I'm inclined to agree initially. But ask a simple question.. What is that depth of penetration where such rotational momentum from the fletchings(Frictional resistance to air molecules) stops and the force of single bevel is the main rotational momentum engine? ...remember the definition..."Energy is conserved over "Time"...which in this instance...each millisecond that passes (time)..you achieve depth of penetration (Distance).
At this transitional point where the single bevel becomes the "Engine" to maintain rotational motion and shaft friction is equal...based upon the law of conservation of energy....in comparing single bevel to double bevel....it is easily assumed that from that specific "Distance"... the double bevel head will ALWAYS out penetrate the single bevel due to the finite magnitude of energy in the system being used more efficiently to maintain only forward momentum...no energy from the finite system is taken from forward motion to support rotational motion such as the single bevel induces. The single bevel head imparts a large magnitude of rotational friction due to forced mechanical action over time/distance inducing angular frictional forces at a higher magnitude the double bevel does not experience. (Newton's Third Law of Motion states that any time a force acts from one object to another, there is an equal force acting back on the original object.) Think of it this way...if that bevel edge is pushing meat away from that small surface area..in opposition to that is the meat on the other side of the blade pushing back....this is seen as frictional force angularly in opposition to the direction of the cutting action. That energy has to come from somewhere...and in a closed energy environment...it can only be taken from the closed system..meaning...less forward distance traveled which was the priority energetic effort.
In more easily seen example....Such loss of energy or efficiency to forward momentum can easily be seen in Nascar...You tweek the downforce applied to the car...with the engine being constant in power output...the efficiency of the forward momentum (speed/velocity) is affected as you increase or decrease downforce...you go faster with less downforce....you go slower with more downforce...same with the edge on a single bevel...this forces too much constant downforce (in nascar terms)...equals...energy taken from forward momentum...thus double bevel being more efficient in conservation of energy consistently gains deeper penetration.

With the killing of a bunch of critters over a few years during my studies on this specific mechanical difference....we were easily able to see that this single bevel technology which has been around for hundreds of years....just wasn't providing any additional benefits on average...like racing in a straight line...the car with too much downforce will get to the finish line....just not as fast as the car with less downforce....but in the end..both are still able to run a good race! And how both styles of bevel easily killed critters in a consistent manner with no real definable winner to lethality...

Look forward to some thoughts from ya'll....as I'm always willing to keep an open mind and learn myself some more good stuff!

jeff

While it is true that an arrow with a single-bevel broadhead will use some of its kinetic energy for rotation (which in general would inhibit penetration), the geometry of the single beveled edge allows it to be thinner and therefore potentially sharper, which allows it to use less of its energy for cutting (which would in general enhance penetration).

So there’s a tradeoff there.

I think I’ve read everything Ashby has written on broadhead performance, and whenever he talks about the advantage of single-bevel broadheads over double-bevel designs, he states that the overwhelming advantage of the single bevels is when bone is encountered. Encountering bone induces a very strong rotation in single-bevel heads, which generally causes the bone to split. A double-beveled head, on the other hand, will tend to “punch” through the bone leaving a clean hole. (Pictures are included in the article referenced above that show the different effects that each type of broadhead has on bone.)

Regardless of how the bone is breached – split/shattered or "punched through" – some of the arrow’s energy will be consumed to that end, thus reducing the penetration potential of the arrow. But Ashby’s argument for the superiority of single-bevel broadheads relates to the shaft as it follows the broadhead through the bone. He argues that the shaft will encounter less resistance as it passes through the single-bevel-induced split/shattered bone, enabling the arrow to retain more of its energy for penetration.

WoodySanford

I had a article published aboutwhat I find in TBM this year where you can read the majority of it but with less volume of materail to support the edge I found retention of the edge lacking. Especialy when encountering bone. I also didn't find the benefit of the rotation in bone. In larger animal ribs it caused the head to carry the rib further, which increases the time resistance is present. The larger tips shattered bone better but exhausted energy far greater on penetrating hide/ribs and causing an increase in the direction arrows take on impact. So I didn't see the benefits as reported by others.

__________________
Best broadhead is a catagory not a single design!

I am "Ferral" and I dig it baby!

jeff

do you have a link to the study? i'd be interested in seeing how the study was conducted, what broadheads were compared, the raw data that were collected, and how the data were analyzed.

WoodySanford

The article was published in TBM, so unless they have put it on line, no I don't have a link. It also wasn't a dissertation on study, it was a explination as to why we were not following that trend.

"Data" can only represent an end result. I would be very skeptical of anyone that said they have put a number to a specific event in the system of penetration and edge retention also falls under that.

I'll be putting up the microscope pictures of the edge later this fall, just haven't had time yet.

Direction taken from impact is pretty easy to see but again not something you can asign numbers to. You can view something that increases or decreases it consistently but its not going to be the exact same all the time as an animal is not a consistent medium.

Its worse of course on larger more dense animals.

But even with higher energy equipment (a 520 grain arrow at a velocity of 275) it can still be seen even on smaller southern whitetails. If you watch this video several times you can see the upper arrow take more direction on impact and more over all than the lower. It was set up out of a shooting machine to square a rib on both shots.

I used to document results with the use of a cronograph that is 12ft by 10ft, similar to what is used in a DART or Technohunt system and force measurement guage's, sometimes I still use them but they only show an end result and give little to no information as to why something penetrated less. I've also never, not once seen something to show an increase in resistance penetrate better unless a higher energy was used, be it weight or a significant increase in speed.

I use mostly highspeed video now. It can give me a loss in energy if I use a graph behind the subject and calculate frames per second into feet per second over a specific distance. I can see something slow down more and I'm willing to bet the farm that shows a decrease in energy and since its going to vary from location to location, I'm fine with that and more concerned with why.


I've watched hours and hours of this stuff over the last decade for work and like the microscope pics I'll be putting as much as I can up on the net this year, just takes time. I also take stills from this video and go frame by frame and find a lot of suprising things.

I've seen huge differeces in how tips penetrate hide and in some cases I have seen hide stop a head and push it backwards.

I wish the single bevel would have worked out. When we grind a head it takes several passes on each side of the bevel and then a worker flips it in the fixture for the other side. A single would have sped up grinding production significantly and we would have produced somewhere between 30-40% more heads a day in our grinding operation and with as many heads as we make, that would be a big savings. It also would have been easy to put into production and we would have done it on all of our heads except the Buzzcut. So it wasn't taken lightly in any way, it was deeply explored and we did not see the benefits of it. Based on durability of the edge alone, that was enough to stick with the double bevel. Sure deer aren't as hard on edges but people use our same heads on moose as they do deer.

I'll also add I agree with Arrowds on rotation as a second vector applied to work done but I'm not going to go digging up Newtons theory of rotational drag, I just got done reading several Whinnie the Poo books trying to get my daughter to sleep and the contrast would likely send me to the store for beer and its to late for that. :-)

__________________
Best broadhead is a catagory not a single design!

I am "Ferral" and I dig it baby!

wyetterp

Thanks Woody. Very interesting. That post helped change my outlook. Looking forward to more from you.

__________________
Experience is something you don't get until just after you need it.

Standing Bear

I think its time to add a bit of pertinent information regarding the discussion of single versus double bevel edges.

You will be given alot of factual based information and in the end, its up to you, the bowhunters to make your decision on what you want to shoot.

If your new to bowhunting or have always had questions regarding the various bevel designs out there, this is the place to be.

Thank you Woody and Matthew for sharing your hard earned knowledge with everyone here on BHT.


Daniel

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Authorized Athens Archery Dealer, Athens Factory Staff Shooter Swhacker Pro Staff

jeff

Data are not limited to numbers. Data would be the collection of information that was used to draw your conclusions – which is what I was interested in.

For example, in the video of the grizzly - what exactly is going on in that one? i can't see an arrow at all. what kind of broadhead was used? what types of conclusions are drawn from that video? what does it have to do with single vs. double bevel? does that video demonstrate the superiority of one type over the other? how and why?

in fact, i have the same questions about all the videos in the above post.

i'm not trying to say your conclusions are invalid - i'm just trying to understand how you came to them.

if this is meant to say that rotation "robs" the arrow of some of its translational kinetic energy - well i would hope that no one would disagree with that.

WoodySanford

My use of the term "Data" is in regards to converting information to a number, to sum things up in a quantitative manner. Thats "raw data" to me. The use of video to me is an observation that is more qualitative, so I interpret the two differently and see them as separate.

The tip of the green arrow stays on the nock in the griz footage, if you look closely you can see the white fletching move around as well. The arrow changes direction off the rear of the scapula and then again off the rib to the rear. It has to do with tip design and since this is more about Ashby's work, I added it in. Most heads using the single bevel are also using the much larger, steeper "Tanto" tip as well and that becomes a part of it. Sorry if I wasn't clear on that. I see more damage done to bone from the steeper tip angles than from the single bevel and rotation but that has a cost in softer more elastic tissue when your not hitting bone like a scapula.

Tips that "Bust" bone create a lot of direction, especially on ribs that are easier to cut than break due to their flexability and mounting to the skeleton via a joint and cartilage. I see the tip taking a back seat and the single bevel taking credit for what the tip does on heavy bone and when not encountering heavy bone the single bevel just increases drag by rotation and the tip still costs you to complicate things.

The video's are examples of how easy it is to see how aspects of head design make a difference and thats what I draw my conclusions from. A number at the end just tells me something didn't work as well, from high speed video I can see what made a difference by changing only that one thing and see how much influence it has. I have quite a lot of video on one vs. the other, in the same head and against other heads that are on the market. Just haven't had time to edit all that up, thats a 40-50 hour project but I will eventually get it done and up.

I wrote the article due to the volume of calls we have recieved on the subject and in this case reported what I find. I'm not into naming the heads tested, I'd much rather just stick to the aspect of design. You will see some of them in the future video I'll be adding to the net but I'll leave it at that. I'm not into calling anyone out.

I didn't take your post as a challenge of my findings, I was only answering your questions with what I have on the internet at this time. As you asked

"i'd be interested in seeing how the study was conducted, what broadheads were compared, the raw data that were collected, and how the data were analyzed."

I was covering the "How's"

I have a site built and up, its woodworksmedia.com but I just haven't had time to add content yet. We are in our busy season and soon I will be doing nothing but field work for the next several months. In that time I will find some to edit and fill the site and there will be video specifically on this subject. If I was to find what others report I would have found the single bevel slowing less in video but I didn't find that, not even on shoulder hits.

__________________
Best broadhead is a catagory not a single design!

I am "Ferral" and I dig it baby!

cartman308

amen brother! The members make our "jobs" so easy!

keep it up guys!!!

Oh my 2 cents. Single or double bevel makes NO difference in my mind period, regardless of the animal I'm going to pursue. I put more thought into the materials used, construction, and tip design than what the style of edge is. I feel that these have much more impact on penetration and durability than the edge style. Just my personal opinion, but I'm not engineer

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