Single Bevel Broadhead rotation inside target/critter

[KentuckyTJ]

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.

   

[Jayrod]

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!

[RC]

I know I  can get the grizzly sharper than anything I`ve tried.RC

[wapiti792]

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

[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.

[stonewall]

RC I like the way I can get them grizzlys sharp too

[Steve O]

Originally 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.

[Kris]

 

"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

[NBK]

"Bernoulli's Principal" given at 7:35 in the morning!
Somebody is bringing their A game today!

[Kris]

You "Da Man" Mike!  See you Saturday/Sunday at WTA State?

Kris

[old_goat2]

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!

[Kris]

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

[JimB]

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.

[Kris]

 

"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

[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.

[Rick Wiltshire]

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.

[Steve O]

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.

 


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

[zipper bowss]

Originally 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.

 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.    

[Kris]

 

"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