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Carbon
vs. Aluminum Arrows by Tom Brissee
The evolution
of the arrow shaft began when the first bow and arrow set was invented.
Historians state that this happened sometime during the Paleolithic
era (35,000 to 8,000 BC.) Someone came up with the idea that, instead
of throwing a spear at their food of choice, they could use a large
"stick" and a piece of vine or twine, to propel a smaller
spear at a higher rate of speed and harvest their food more efficiently
by using a greater amount of the force applied to this small spear.
It is my guess that they built a bow and several arrows and practiced
like crazy to become proficient. It took patience to find the right
material to fashion arrows from which would yield good, consistent
arrow flight For 1000's of years, man used wood to make his arrows.
Some archers still use wood but, like all of man's activities, study
and innovation resulted in improvements to the materials used to
make arrows, as well as bows and bow accessories.
The first step
up from wood was aluminum. Wood began as the material of choice
because it could be shaped and straightened into arrow shafts. Through
experimentation, it was found that a straight arrow shaft would
fly more accurately than a shaft which was less straight. Wood was
used as the sole material for arrow shafts until man discovered
that metals could be mined from the earth, heated and molded into
a desired shape. It was found that when the first metals, such as
bronze, copper and iron, were used as arrow shafts, they were much
too heavy and would fly only short distances. These metals became
useful as points for arrows as they could be more easily sharpened
than stones, which were originally used as arrow points. According
to the United States Geological Survey, Aluminum is the second most
abundant metallic element in the earth's crust, with Silicon taking
top honors. Metallic aluminum was first produced by a Danish chemist,
Hans Oersted, in 1825. It is about 1/3 the weight, by volume, of
steel or copper and is more easily machined and cast.
The aluminum
arrow story begins in 1939 when James Easton first began to experiment
with aluminum as an arrow-shaft material. Two years later, Larry
Hughes was the first archer to win the American National Archery
Championship while using aluminum arrows. James Easton continued
to develop production techniques which would yield a more consistent
aluminum arrow shaft. Easton Aluminum produced the first trademarked
arrows in 1946, model no. "24 SRT-X", offering them for
sale to the general public. In 1955, the popular XX-75 arrow shafts
were added to Easton's arrow line. Changes in aluminum arrow shafts
have been few ever since as XX-75's continue to dominate the market
and most archers start off using the XX-75 shafts. Aluminum shafts
provided greater consistency of weight, balance and arrow flight,
when compared to the wooden shafts used by archers previously.
In 1969, Holless
Wilbur Allen was granted a U.S. Patent on his invention of the compound
bow, which revolutionized archery in the United States. This invention
also helped to give greater value to the aluminum arrow shaft. Aluminum
shafts, vs. wooden shafts, have a greater tolerance to the forces
applied to them when shot from a compound bow. When a compound bow
is drawn, the amount of effort used by the archer increases as the
bowstring is drawn back and then drops off during approximately
the final 3rd of the total draw length, known as let-off. When the
bowstring is released and the energy stored in the limbs is applied
to the arrow: the bowstring travels forward and the maximum amount
of energy is applied quckly to the arrow at the strings let-off
point. In contrast, non-compound bows apply a steady amount of energy
to the arrow when the bowstring is released and travels forward.
Wooden shafts, due to their natural inconsistency in stiffness,
would possibly explode into splinters if fired from a compound bow.
James Easton, and other metallurgists, had the technical knowledge
required to measure the stiffness or "spine" of an arrow
shaft which would be consistent throughout the shaft due to the
manufacturing process. The compound bow also possesses the ability
to be adjustable in draw weight. This would require a greater selection
of arrow spines as draw weight changes would change the forces applied
to the arrow shaft. Changes in thickness of shaft walls and the
diameter of the shafts would effect the spine of the arrow shaft,
as would arrow shaft length and the weight of the arrow head used
by the archer. Easton uses a 4 digit number to identify their aluminum
shafts. This number is actually 2 2-digit numbers; the first number
indicates the outside diameter of the arrow shaft in sixty-fourths
of an inch and the second number indicates the wall thickness of
the shaft in thousandths of an inch. A "2215" shaft would
be 22/64" in diameter and have a wall thickness of 0.015".
Release aids
have become popular with archers over the last 20 years due to greater
consistency in arrow flight, when compared to arrows shot by drawing
and releasing the bowstring with fingers. Slow motion film techniques
have helped us study these issues to understand the reasons why.
When the bowstring is released by the archer's fingers, the string
will move around the fingers horizontally in one direction and then
correct itself by moving in the other direction as it travels forward.
The arrow shaft will also flex as the bowstring travels forward.
This flexing of the arrow shaft is know as "archer's paradox".
If the stiffness (spine) of the arrow shaft is too low, the forces
applied to the shaft when the bowstring is released could cause
the arrow shaft to break. The correct arrow spine will allow for
the shaft to handle the paradox and stop flexing a short distance
after it has left the bow which will yield good arrow flight as
the feathers of the arrow control it's flight. Release aids minimize
the amount of string movement from side to side and add consistency
because the string movement is the same with each shot. Arrows used
with releases require a shaft with a stiffer spine than finger-shot
arrows because there is less flexing required to provide good arrow
flight.
Now that we
have an idea of arrow flight characteristics let's look at the advantages
of shaft materials. Wood was the first material to be used for arrow
shafts. It was easy to obtain but required proper manufacture and
a lot of testing to come up with a wooden shaft which flew well
consistently. It became obsolete as a shaft material with the advent
of the compound bow, although it is still used today by traditional
(non-compound) archers. A good number of the non-compound archers
have adopted aluminum as their arrow shaft material of choice, due
to it's availability and durability in comparison to wood. Easton
aluminum has provided all archers with the "Easton Arrow Shaft
Selection chart", which shows which of their shaft sizes should
be used, based on details such as the type of bow, type of compound
bow cam, arrowhead weight and draw weight and draw length. This
has made it easy for the average archer to determine which aluminum
shaft(s) will work well with their bow, simply by using the Easton
chart. Aluminum arrows are commonplace and hold a good portion of
the arrow shaft market. This makes them relatively inexpensive and
easily replaced when needed, simply by going to the local bow shop
or ordering them through a mail order catalog.
Carbon arrows
were first developed, again by Easton Archery, in 1983. When carbon
arrow shafts were first introduced and hunters became aware of their
existence, rumors began to fly that the shafts were brittle and
, when broken, they would splinter into long, sharp, pine-needle-like
fragments. Sure, there were early problems but this occurs in the
early stages of any new innovation. It takes a while to get it tweaked.
Carbon arrow shaft production evolved to produce spiral fiber-wrapping
and cross weaving of the carbon which increased the durability and
strength of the carbon. Carbon arrows have the ability to maintain
their straightness. It has been said that "they're either straight
or their broken". In contrast, I personally have a collection
of aluminum shafts, in a box in a back room, that have are no longer
useable because they have been bent or dinged by other arrows when
shooting. Aluminum arrows can be straightened but I think that once
you bend an arrow, you weaken the shaft at the inside-bend. I have
switched exclusively to carbon arrows and don't see any reason to
go back, in my opinion. Not to say that carbon is better than aluminum
if that's what you shoot and it works well for you. It's a confidence-in-your-equipment
issue.
I tried carbon
arrows first when I decided to splurge on some skinny Beman's 5
years ago. In comparison to the 2413 XX75 Superlites (aluminum)
that I was using at the time, the Beman's were about twice the price,
half the diameter and two-thirds the weight. They had outserts to
screw the points into, external-shaft nocks and the fletching just
barely fit on the shaft to allow clearance through the rest. Due
to the narrower shaft, I had to change my launchers on my prong-style
rest so the shafts would not fall through. I'll admit I wasn't the
tuning "expert" that I am now, (said with tongue planted
firmly in cheek) but I had a difficult time with these shafts getting
them to fly right. Fletching contact was the big issue as the narrow
shafts left very little room for arrow because the rest prongs were
so close together.
A couple years
later, I was lucky enough to win some Carbon Express 300 shafts,
a whole dozen, in a raffle at a bow-league banquet. I had just purchased
a new bow and the overdrawn 300s picked up 25 fps for me in bow-speed
over the aluminum arrows, due to their light weight. These arrows
were much closer in diameter to the aluminums and had internal-shaft
nocks and inserts just like the aluminums. Can't say I ever bent
one. I did pick up some tighter groups and only broken nocks stopped
me from using them. Aluminums would slap together in the target
and you could tell by the sound of the impact that one or both of
the shafts would be damaged; carbon proved, to me, it's durability
over aluminum.
I enjoyed the
carbon shafts quite a bit. I began to do some calculating and study
of arrow physics, particularly kinetic energy and momentum. Jackson's
Archery website provides arrow weight calculators for various brand-
shafts, aluminum and carbon, kinetic-energy calculators, FOC (front
of center) calculators based on point-weight used and momentum charts.
The momentum charts show the theoretical KE downrange from the bow
at various distances. Light arrows will lose momentum quicker that
heavier arrows. I decided to look for a happy medium between the
ultra-light carbons and the heavier aluminums. Cabela's Stalker
Extreme 55/70 shafts were the answer for me. The arrows are produced
by Beman, and have internal components. They are a larger diameter
shaft, compared to the Beman's that I used previously, so there
was no issue with fletching contact and their weight was lighter
than aluminum shafts of the same length, but heavier than my previous
carbon shafts. And the price was about ½ of the C-E 300's.
A good deal all around that has proven to be just the ticket for
my bow set-up.
Keep in mind
that there are many opinions about equipment choices. Bottom line:
decide for yourself what works best for you and keeps your confidence
in your equipment high. Confidence equals success.
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