Arrow speed, arrow weight, accuracy, and penetration

Arrow speed, arrow weight,
accuracy, and penetration
By John Dudley
John Dudley argues that broadheads should be used at
relatively slow speeds – under 280 fps. A heavier, slower-flying arrow makes for good accuracy, he says, and
if the bow-arrow combination is well tuned, the arrow
will have more penetrating power than a lighter, faster
arrow.
I
n the fast-moving field of archery we consumers are constantly being hit with new, improved products. It seems that
the demand for speed continuously drives the manufacturers
and buyers to develop new technology. It’s nature, I guess, that
we like to have the fastest and highest-performing product we
can get our hands on, and the bottom line is that speed still sells.
Equally noticeable to me is that in some countries -- like the
USA, Africa, Australia -- that have large game animals, people
are electing to have high-poundage hunting bows. Fast designs
and heavy pulls can definitely have their advantages, but many
people who aren’t educated on speed and heavy pulls don’t realise the effect it has on arrows tipped with certain broadheads.
In my opinion marketing is a powerful tool to any company as
long as education goes along with it! Most people simply believe
what they read or what is advertised and never actually test the
claims for themselves. Truth is, our industry is filled with misleading ads and marketing. However, if you are smart to your
set-up, you can still come out way ahead of past performances
with this high-tech equipment. Don’t get me wrong, I am thankful to the innovative companies and their new products because
speed is valuable, heavier poundage is valuable, but so is proper
education. There are several benefits to speed and also to heavy
poundage, and by the end of this article I believe that you will
be a lot smarter about how to configure your bow for the best
combination of speed and poundage.
Consider what is up front
Speed is a touchy subject for hunters because the biggest problem in this equation is broadheads. When deciding the speed
of your set-up, you need to first consider the broadhead you
are going to use, whether it is fixed-blade or mechanical, and
compact or large-cut. I have done independent testing on countless numbers of broadheads, arrows, vanes, bows, etc. Without
going through all the thousands of variables, I will tell you this:
a lot of the time, a fixed-blade broadhead will be most effective if the speed is kept under 280 fps. Like I said, the factors
that affect this are countless. Factually stated, arrows under 280
fps tend to be much more likely to group above expectation,
and they are amazingly effective. An important factor in this
is most obviously the type of broadhead you choose. Without
being biased, I can tell you that the best-grouping heads I have
shot to date include Shuttle T-Lock, G5 Striker and the Rocket
Bacon Skinner. I am not going to say these are the only three
fixed heads that perform well, because I haven’t tried everything on the market and at times other brands have shot well.
However, all things factored in, those three gave the most consistent grouping. As for durability, I would rate these heads in
the same order as above with the Shuttle being the best, due to
the blade design and how it fits in the ferrule.
If you aren’t shooting a fixed-blade broadhead, then obviously you are shooting a mechanical-deployment broadhead. In
my opinion this is a much better option if you are only concerned with shooting very fast speed. There are many goodlooking mechanical heads on the market, and for speeds over
280 fps these simply perform the best – regardless of vanes,
shaft selection, distance shot, etc... The argument of fixed
blades vs. mechanical heads can go on forever and ever. Each
has its benefits, without a doubt. Only you yourself will know
what suits your application in hunting and equipment choice.
I am not here to tell you which one to use, I am only here to
tell you that with all market BS to the side, you need to know
that your choice in speed should also determine your choice
in heads. I personally see a fixed-blade broadhead to be a better choice, after factoring in all things, for 80% of my hunting
applications. So for the most part this article will be geared to
those readers who favour a fixed-blade broadhead.
Arrow education
Just like fast bows, there are also arrows that are marketed for
speed. For some applications a fast, light arrow can be advantageous. I have used them myself in the past for pronghorn
The Axis FMJ DG Gunmetal arrow, 300 grains.
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A BFM of the Alpha Max 35
and an FMJ Dangerous Game
arrow.
antelope, impala or European
roe deer. When hunting animals that I know to have quick
reflexes I tend to choose a
faster arrow. I do this to try to
minimise the opportunity for
the animal’s vitals to change
location from where they were
when I shot. However, when I
am shooting very fast I know
that it also means shooting a
mechanical broadhead. This is not always my preference. The
trade-off for a lightweight arrow is a lower impact force when
hitting dense bone. When you combine less kinetic impact with
a mechanical head then you tend to minimise penetration potential. That is why I use light, fast arrows only for smaller game
animals. In opposition to the lighter arrows on the market there
are also arrows that have a higher mass/weight rating per inch
of arrow shaft. In years past, heavier arrows usually meant they
were massive in diameter as well. Nowadays though you can
get heavier arrows that are still small in shaft diameter. This
is important because the weight is needed for energy, and the
small diameter is needed for maximum penetration and minimal air drag. Heavier arrows have many benefits but most people are detoured to do a slower speed. I believe people tend to
think that a lighter, faster arrow is more effective than a slower
arrow. That is only true if the arrows in the equation are the
same weight. For example, a 400-grain arrow at 300 fps would
be more effective than a 400-grain arrow traveling more slowly.
Here in the States many hunters do not know this. They believe
faster means harder-hitting. In Africa though I think bowhunters are much better educated on the benefits of a heavier arrow
and its importance to penetration and kinetic energy. Do you
think a lighter arrow going 325 feet per second would have more
impact than a heavy arrow going 258 feet per second? To prove
this point, here are some factual numbers for you to think about.
These are actual numbers taken directly from my personal bow,
the Hoyt Alpha Max 35, set at 80 pounds peak weight. My draw
length is 31 inches:
• A 400-grain arrow will shoot at 325 feet per second.
• A 700-grain arrow will shoot at 258 feet per second.
To calculate kinetic energy you need to use this formula:
0,5 x mass x velocity x velocity = kinetic energy
The factors that I have from my Alpha Max show that the 400grain arrow produces 93.84 pounds of kinetic force out of the
bow. The 700-grain arrow produces 103.49 pounds of kinetic
force out of the same bow! The same bow with an arrow that
is 67 feet per second slower out of the bow produces nearly 10
30
Easton's new HIT brass insert weighs 75 grains, but a break-off
section allows reduction of the weight to 50 grains.
pounds more kinetic energy! Also keep in mind that this is the
speed out of the bow. The equation would favour the heavier
arrow even more farther down range. This is because the heavier-weight arrow will retain its energy better than a lighter arrow
the farther it travels. It is simple physics of mass in motion.
Now that you know the factors of mass, weight and speed,
you have a lot more to think about. If you are shooting animals
that have fast reflexes or are in a hunting situation where you
have to make quick shots at unknown distances, then speed can
be advantageous. However, if those factors are not relevant then
a heavier arrow will be a better choice. Heavier arrows have
more kinetic impact and better penetration, and the higher
kinetic energy allows for the use of larger cutting-diameter
broadheads. Earlier I talked about speed and that a slower arrow
tipped with a broadhead is more stable than a faster arrow. This
is very true. An easy way to think on this is to think about the
last time you were in a car driving with your hand out the window. If you point your hand forward and move it slightly up and
down you will quickly see that it is much easier to control when
you are driving slowly than when you are going faster. The faster you drive, the faster the air takes your hand in one direction
or the other. This is the same principle that restricts most people
from getting broadheads to group consistently with field points.
A bladed tip is easier to control at a lower speed.
Let high performance help you, not hurt you
Now that you have all this new information about speed and
energy, let’s put it to good use. Bows are getting faster and faster. Speed is valuable, but like I said: let it help you. I personally believe that today’s hunters would be much wiser to select
a heavier design of arrow shaft to go with the high speeds that
are being achieved. By selecting a heavier arrow, you will benefit by reducing the velocity of the shaft to a more manageable
speed, which will make it group better and also achieve better
penetration. So if you are shooting a heavy-weight bow or a
bow that is screaming fast out of the box, using a fixed-blade
broadhead, then I would highly recommend that you try to find
as heavy an arrow as possible to get the speed under that 280fps mark. I think you will be much happier with the results!
To aid heavy arrows, Easton also came out with a very cool
accessory. This year they introduced a new brass HIT insert.
This insert is designed to fit any of the Easton shafts that allow
AFRICA’S BOWHUNTER APRIL 2009
fortheHITsystem.Thebrassinsertis75grainsinweight,but
has a break-off section that allows for reducing the weight to 50
grains. This heavy insert is valuable in many ways other than
just adding total mass. For example, in order for arrows to fly
well it is important to have a high percentage of FOC or frontof-center – meaning the heavier the weight in the front part of
the arrow, the higher the FOC. If the FOC is high (over 13%)
then the ability of the arrow to fly true is much better. Here is
how I used this new insert system for my personal bows. For my
dangerous-gamearrowsIusedthe75-graininsertandwasable
togeta700-grainarrowwitha125-grainbroadhead.Again,
Ishootthe700-grainarrowoutofmy80-poundAlphaMaxat
258fps.However,whenIshootmyAlphaMax35at70pounds,
I use the 50-grain inserts inside a standard FMJ 300. This arrow
weighs nearly 500 grains and shoots at around 280 fps. What
I like about the 50-grain insert for the lighter arrow is that it
allows me to shoot a 100-grain broadhead while still having 150
grains of total weight in the front of the arrow. So I have great
FOC and also have good arrow flight, since the 100-grain head
is more compact then the 125.
I think these heavy arrows and heavy inserts have been
needed for a long time. I am a firm believer in innovation and
improvement. Archery gear constantly improves and changes,
and it is great when the improvements help the person using the
product. But sometimes technological advancements reduce the
outcome for the user. Bows that are fast definitely have their
advantages, but only if used correctly. I believe that using the
speed of the bows to allow for using heavier arrows is the biggest advantage. A perfectly placed arrow results in death within
seconds. A poorly placed arrow is exactly the opposite. I know
that most of you out there are no different than I am. You spend
a lot of time working hard to save to hunt. Then you schedule a
trip and eagerly anticipate it for months before it comes. The biggest reward is being successful on that hunt. The worst feeling
is coming home empty-handed. Be wise about your equipment
and make sure that your bow and arrow set-up is shooting as
well as you are capable of. You will enjoy shooting and be more
successful when hunting when you have a bow that is forgiving
and enjoyable to shoot. It will also boost your confidence and
put more arrows in the vitals. Before you head out to the bush
with the fastest arrow in camp, make sure that a slower, heavier
arrow wouldn’t have been the better choice. You won’t know if
you won’t try. I know I personally have weighted it all out and
the best thing about the fast bows is that I can finally shoot seriously heavyweight and destructive arrows while maintaining
high performance.
T
Best of luck in the field!
Action of Axis' Bone Crusher.
The author with the moose he bagged using a Hoyt Alpha
Max bow, set at 80 pounds, and an Easton FMJ Dangerous
Game arrow.
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