Well, I had someone ask me the other day how do I know a single bevel head continues to rotate inside the deer. Well I told him that I have seen where the slits on the inlet side and the slit on the outlet side never line up like the head stopped rotating inside the deer. I have also pulled many heads from my target while practicing and can fell and see the head spinning as it follows its entrance trail coming back out as I pull it from the target.
So I thought I would make a video of that to share and here you are. I drew a straight black marker line on the shaft so you can see the shaft as it spins out. Shaft only went in about a foot.
https://youtu.be/DdYTktMYtXY
Yes sir brother I actually thought of you tonight shooting my single bevels... when I pulled them outta the target I can feel the twisting in my hand you converted me to single bevels and it's was hard to do but when you harvest a animal the proofs there in the results for sure!
I know I can get the grizzly sharper than anything I`ve tried.RC
I am unsure on rotation but the crazy quick down in site blood trails are a thing of beauty Tom. Great stuff though!
There is no doubt that you can feel the arrow turning as you pull one with a single bevel head out of a target!
Bisch
The blade has more surface area on the side of the bevel which creates a pressure differential causing it to keep turning, it's very similar to the reason an aircraft wing creates lift. What's weird is the top of an aircraft wing has more surface area causing the lift on the bottom, but the single bevel pushing through whatever target media happens to be developed more pressure on the bevel side.
RC I like the way I can get them grizzlys sharp too
QuoteOriginally posted by old_goat2:
The blade has more surface area on the side of the bevel which creates a pressure differential causing it to keep turning, it's very similar to the reason an aircraft wing creates lift. What's weird is the top of an aircraft wing has more surface area causing the lift on the bottom, but the single bevel pushing through whatever target media happens to be developed more pressure on the bevel side.
Exactly. It is simple physics. It has to! Next time you are in a Super Cub flying out to your hunting spot notice the wheels aren't turning while you are in the air...because the pressure is equal going over and under the wheel, unlike the wing giving you lift.
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"the top of an aircraft wing has more surface area causing the lift on the bottom, but the single bevel pushing through whatever target media happens to be developed more pressure on the bevel side."It's not the same physics (pressure) reacting on an airplane wing creating lift versus a single bevel BH causing rotation.
The lift or pressure differential on a wing is a result of Bernoulli's Principle.
A single bevel head rotates because of the force exerted upon the bevel itself, it would be more akin to the control of the airplane do to flap orientation.
Push a single-beveled head through a potato or any similar dense media, like the foam in the video above and allow it to rotate freely. Ashby's writings cover all of this in great detail.
Most guys think too, that a single bevel head goes through a deer spinning like a top...not so. About one complete rotation every 16" or so, it depends on the degree of bevel but less than two complete rotations, side to side, through an average deer.
The "liquidated lung phenomenon" that guys refer to can exists with any BH shot through the lungs, not because a Grizzly (or other SBBH) "egg beats" the lungs, do to its spin.
I am a single bevel guy...I'm not minimizing their attributes.
Kris
"Bernoulli's Principal" given at 7:35 in the morning!
Somebody is bringing their A game today!
You "Da Man" Mike! See you Saturday/Sunday at WTA State?
Kris
That makes sense, that explains what I couldn't figure out, by my line of thinking it would turn opposite of what it actually does. Thanks Brother!
old_goat2
You are welcome Brother! All good stuff for those that care to think about it. I enjoy understanding things at the most fundamental level...keeps it interesting IMO.
If I am wrong about the above...call me out please.
Kris
I shoot broadheads into a 4.5" thick slab of minicell foam,mounted in a frame.It stops the arrow but 20 some inches protrude out the back side.
I shooting 190-200 gr Grizzlies and 300 gr Tuffheads,they rotate 1/4 turn when pulled through the 4.5" slab.Doc Ashby says one full turn in 16",so this sounds about right.
Here is the kicker though.The arrow continues to rotate after the broadhead clears the foam slab.I have to rotate the shaft quite a bit in order to match the blade to the exit slit before I can pull it through.This is very consistent and happens with every shot.I have no explanation for this.In my mind,that shouldn't occur but it definitely does.
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"The arrow continues to rotate after the broadhead clears the foam slab"Cool observation! One explanation might be that the rotational momentum is similar to directional momentum...in other words the arrow continues to rotate even after the bevels are no longer engaged with the media that is the resistant force driving that rotation.
I wouldn't think it that strong either, but I'm glad it is! We all know how hard it is to stop a spinning bike tire but that has so much more mass and diameter, etc. All sorts of forces play a role here...you can read below.
https://en.wikipedia.org/wiki/Angular_momentum
Kris
JimB,
I think I am way under qualified on my own thread at this point but my uneducated guess is the fletchings are following the rotating path cut by the single bevel head.
There will also be a certain amount of turning momentum imparted to the shaft by the single bevel as well as the fletching that will continue till the friction of the material it is going through overcomes the turning momentum.
QuoteOriginally posted by KentuckyTJ:
JimB,
I think I am way under qualified on my own thread at this point but my uneducated guess is the fletchings are following the rotating path cut by the single bevel head.
:laughing:
Momentum baby...
Maybe I oversimplified saying "simple" physics :D
Thank goodness for the good Dr., Larry Hanify, Joe Furlong, and Bill Dunn. All REALLY smart guys with great products
QuoteOriginally posted by Steve O:
quote:
Originally posted by KentuckyTJ:
JimB,
I think I am way under qualified on my own thread at this point but my uneducated guess is the fletchings are following the rotating path cut by the single bevel head.
:scared: Hey, Steve Don't lump me in with guys that know what they are doing.The next thing you know people will expect something out of me. That could be dangerous to my leisure time. :biglaugh:
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"guess is the fletchings are following the rotating path cut by the single bevel head.""Ironic isn't it?" the fletching starts the rotation, the bevel takes over through the tissues and the fletch likely compliments that continued rotation out through the exit.
I never actually thought about the fletching orientation causing rotation through the tissues but there is no reason to believe that it does not compliment the spin of the shaft. I know pulling arrows out the back of a foam target, that the fletching certainly imparts a rotation to the shaft; whether this exist within a bloody cavity remains unseen but I would believe that it does, especially through denser tissues like muscle, etc.
Another very important consideration when matching the wing of the fletch with the bevel of the BH.
Good stuff, thanks for the post!
Kris
QuoteOriginally posted by KentuckyTJ:
JimB,
I think I am way under qualified on my own thread at this point but my uneducated guess is the fletchings are following the rotating path cut by the single bevel head.
TJ,I think you are exactly right.The only explanation I could come up with,is that the broadhead passes through the 4.5" of medium very quickly and the fletching induced rotation keeps doing what it does.
If the fletching was not matched to the bevel,would this still happen?I don't think so but at some point,I'll give it a test.
When I first started shooting single bevel I did it because a friend made the broadead. I didn't really buy the idea that the blade would rotate once it encountered resistance (the target or animal). The seller didn't talk so much about that as he did the way the single bevel, with rotational force, would interact with bone (read leg bone) if hit.
However, when I removed these broad heads from foam targets, like others have reported, you have to rotate them out or tear hay-jack out of your target.
I did screw up that first year though because I used opposite wing feathers that didn't match the single bevel. My fletch and broached weren't working together as the should. Two deer ended up in the freezer in spite of my error.
I took this potato and pushed a single bevel broadhead through it as it turned he potato, you can see the S.
(http://i297.photobucket.com/albums/mm216/ranger500us/IMG_0621.jpg) (http://s297.photobucket.com/user/ranger500us/media/IMG_0621.jpg.html)
I've been using single bevels for years. I"ve shot 2 moose, 2 deer, a black bear and some other animals that either ran in a semi-circle or did a spin just before they went down. By golly...there might be something to all that blade torque! ;)
Good thread TJ....thanks!
:clapper: Now that is putting the torque to them, Kevin
Nice on the Spud pic Howard.
Kevin, thats because when they realized who shot them they instantly turned around wanting to meet you!
QuoteOriginally posted by Kris:
Quote
"guess is the fletchings are following the rotating path cut by the single bevel head."
"Ironic isn't it?" the fletching starts the rotation, the bevel takes over through the tissues and the fletch likely compliments that continued rotation out through the exit.
I never actually thought about the fletching orientation causing rotation through the tissues but there is no reason to believe that it does not compliment the spin of the shaft. I know pulling arrows out the back of a foam target, that the fletching certainly imparts a rotation to the shaft; whether this exist within a bloody cavity remains unseen but I would believe that it does, especially through denser tissues like muscle, etc.
Another very important consideration when matching the wing of the fletch with the bevel of the BH.
Good stuff, thanks for the post!
Kris [/b]
Agreed Kris, I didn't think of that either but definitely think the helical fletchings would continue rotation even in soft liquid matter inside a critter the same as they do through the air. I see a underwater camera and test video in the works. Someone with a slow motion underwater camera, an assistant and a pool please carry this out.
I single bevel all two blades whether they come that way or not. Not only do I like the single bevel results, I can get them sharper too. Win - win!
This is my first year using single bevel. They do rotate in target.
They also seem quieter in flight. Does anyone else notice this or is just me.
TJ, et all,
even straight fletched, slight offset, my left wing have a natural helical. Not to the degree that putting a hard helical on the feather when fletching, but it's there-- and my straight fletched, single bevel, still spin all the way thru the target be it foam or meat.
Come to think of it while typing, when I shot STOS 2 blade double bevel + straight fletched, I had to rotate my arrows to pull back thru the block...just didn't get the S thru meat like with the single bevel...
Wouldn't that also suggest that the fletch starts the spin and continues it thru target mediums? The single bevel just enhances that perhaps? And the big reason I like them on game is the potential for a slight off mark hit and bone splitting ability... even with lighter draw weight but heavier arrows...
Doc, I'll have to disagree with you on a two bevel head continuing its rotation from flight through a target. I have shot several types of two blade two bevel heads through that same foam broadhead target and they didn't spin through at all. The outlet slits were exactly the same orientation as the inlet ones.
I'll accept your counter... memory is a terrible thing at this age, and I could be wrong...but I thought that was my experience or I'd not have posted it...
I never could pull them back thru the block and always unscrewed them then pulled the arrow...
Who knows, but I'm with you 100% on the single bev doing it... I'd shot 2 deer with my Tuskers that KME ground for me and the tissue damage looked like a ballistic tip bullet!