ok, first of all, please don't check my spelling and so on...
i translated this text from english to german to english again, so some things may have been lost.
My experience is, that two blade broadheads do leave a very small, near to nothing, bloodtrail.
It usually depends, where you hit the animal, how the hide and the cut tissue bends, flexes, or regains shape...
whatever you call it....
it is a straight cut, which tends to close very fast due to the the movement and the position of the animal... etc.
a 3-blade head rips the hid clearly, no chance of closing only by pressing the cut together...
thats why the blodd can make its way to the hunters field of view....
this is also a reason for a surgeon to cut a triangular shape, while having a difficult op
it just keeps open easier.
so any stable 3 blade head will give you, if everything goes the normal way, a good and decend bloodtrail...
BUT: to get a good bloodtrail, you need a good penetration, a lethal shoot, a decend arrow and so on....
some of those things above are not as easy to achive with a 3 blade head.
penetration will increase with heavy bows... ok, not problem with that, but there are a lot of other important features a good broadhead can give you....
Top 12 Arrow Penetration Enhancing Factors
Structural Integrity
The most important factor of arrow penetration is structural integrity. If any component of your arrow fails penetration either completely stops or is greatly reduced.
Arrow Flight
If an arrow is not flying perfectly it’s wasting valuable energy that could have contributed to penetration. If an arrow impacts before it has achieved perfect flight, energy is wasted that could have contributed to forward momentum and penetration. Perfect flight is crucial, you must achieve it no matter what the cost. Pay close attention to the other factors too though or you may find yourself shooting arrows that fly perfectly but can’t penetrate well at all.
Arrow FOC (Forward of Center)
Tests have shown that EFOC, defined as 19% - 30% forward of center and Ultra EFOC, defined as over 30% forward of center enhances penetration from 40% to 60+%.
Broadhead Mechanical Advantage
Long narrow broadheads have an advantage over shorter wider heads. It takes less energy to push them through an animal. That is their mechanical advantage. This is second only to EFOC and Ultra EFOC as a penetration enhancing factor.
Shaft Diameter to Ferrule Diameter Ratio
You’ll lose up to 30% of your penetration potential if the shaft is larger than the ferrule where they meet. It’s best to be slightly smaller in diameter than the ferrule of the broadhead.
Arrow Mass or Weight
Heavier arrows absorb more energy from the bow at the shot & they carry their momentum better than lighter arrows so they penetrate better. Bowhunters should use the heaviest arrow that will deliver a trajectory they can live with.
Brodhead Edge Finish
Broadhead edges that have been honed and stropped smooth have a 26% advantage over smooth filed edges and a 60% advantage over the coarse “serrated” Howard Hill edge.
Shaft Profile
On all shots tapered shafts show an 8% penetration gain over parallel shafts and a 15% gain over barrel tapered shafts.
Broadhead/Arrow Silhouette
Smooth transitions and slick arrow finishes greatly enhance the penetration potential of your broadhead/arrow combination. Broadhead ferrules with bumps or any irregular surfaces impede penetration, especially in bone.
Type of Edge Bevel
Only if no bone is encountered does this factor rank 10th. If bone is hit, and more often than not it is, this factor jumps up toward the top of the list. If you can’t get through the bone, penetration stops. The powerful rotational force of single bevel broadheads splits bone. Single bevel broadheads regularly turn what would be a wound into a killing shot. Note: Your arrow must be of sufficient weight and strength to drive the broadhead through and withstand the forces involved in breaching the bone.
Tip Design
In all testing where bone was encountered the Tanto tip performed best. It resisted damage and skipped less than any other tip design.
If you use good heavy broadhead, i think above 125 grain, that should not be a problem.
Arrow Mass 650 and Above
When soft tissue is hit, this factor is ranked last in importance BUT if heavy bone is hit it will be near the top of the list. Heavy bone is almost impossible to breach unless you have 650 grains or better in mass arrow weight.
ok, thats all i know about penetration...
but theres more to know about:
Tissue Resistance to Arrow Penetration
Fact: The greater your arrow speed, the greater the resistance to penetration.
Speed in and of itself isn’t bad. Opting for speed at all costs, well, comes at a cost. Here’s one of them. When any object moves through another the object being moved through resists the forward momentum of the other. A good illustration of this is how the wind resists your hand if you put it out the window of a moving vehicle. The faster the vehicle moves, the more the air resists your hand.
There is a formula for determining the degree of resistance various substances have to an object attempting to pass through them. It’s officially called the “Force of Drag” but we generally hear it referred to as wind resistance, or water resistance. This force of drag applies to other mediums as well like animal tissue, including hair, hide, flesh and bone.
The actual formula states:
more on wikipedia:
Drag (physics) - Wikipedia, the free encyclopedia
That’s a complex formula but here’s what it means to arrow penetration:
The faster an arrow is moving the more resistance there is to it. (Even in the air.)
Because the velocity is squared in the formula, the resistance increases tremendously as the arrow speed increases.
If you double the speed of the arrow, the resistance factor increases by four. (2 x 2 = 4, velocity squared.) Here’s where it gets scary. If the arrow speed increases by a factor of four, then the resistance factor increases by 16 times! (4 x 4 =16, velocity squared)
What does that mean to bowhunters? It means an arrow traveling at 150 feet per second is met with four times less resistance to penetration than an arrow traveling at 300 feet per second. Another way to say it is; an arrow traveling at 300 fps has to overcome four times the amount of resistance to penetration than an arrow traveling at 150 fps.
The cold hard truth is.... When it come to penetration, light fast arrows lose the momentum/kinetic energy battle AND when they reach the animal they have to overcome as much as four times the resistance to penetration as slower moving, heavy arrows do.
If you're goal is to gain kinetic energy on paper by shooting lighter arrows faster, science proves it's a lose-lose proposition.
First, you LOSE velocity twice as fast as momentum AND you LOSE penetration potential in what energy you do have left because the medium you're trying to penetrate is resisting that penetration four times more than if you were moving half as fast.
The above facts reveal serious implications to bowhunters who go for 'speed at all costs'. For those who still insist on shooting lighter arrows.... If you care about penetration. If you care about increasing your chances of success and limiting your odds of wounding an animal, you MUST AT LEAST choose a broadhead designed to defeat the increased resistance to penetration.
That all said, i would say:
shoot that broadhead, that is able to take down the desired animal,
the broadhead that give the best penetration and performes best, when it comes to
the actual killing of the animal...
and don't worry to much about the bloodtrail...
if you shoot straight, the bloddtrail won't be long enough to worry about....
(more information on those topics: the ashby reports and
Alaska Bowhunting Home Page)