CROSSBOW
FIELD PERFORMANCE
What to expect from your new crossbow....
HISTORY:
The first crossbows appeared in China as early as the 4th century BC,
and were quickly adopted as weapons of war. By 209 BC, the Chinese army had
over 50,000
crossbowmen. The crossbow’s
principal advantage lay in the simplicity of its operation. One
aimed and fired it much like a modern handgun, and it did not require
the years of practice which were necessary in order to master other
bows such as the English longbow.
Europeans encountered this weapon during the Crusades, and by the
11th or 12th century AD, the crossbow had become a significant
military weapon in the West as well. Capable of penetrating
steel armor at close range, the medieval crossbow was a feared weapon,
and it was widely used as a military weapon until displaced by powder weapons in
the 16th and 17th centuries. |
LEGACY AND MISCONCEPTION: In modern day, the
crossbow has largely evolved into a weapon for sport and
recreation, but it's fearsome medieval heritage has
unfortunately given rise to some misconceptions.
The most common misconception is that a crossbow has
long-range capabilities like a gun. IT DOESN'T! While
the crossbow is often shouldered and fired much like a gun, that's
where the similarities end. In spite of the cool
advances in modern manufacturing and machining, the crossbow
is still a primitive weapon. Today, the average crossbow
generates roughly 80 ft-lbs of Kinetic Energy. By
comparison, a run-of-the-mill .30-30 hunting rifle generates
over 1200 ft-lbs of Kinetic Energy. So if you intend
to use your crossbow for big-game hunting and you expect
it's range and power to be like a modern powder weapon, you will surely
be disappointed. |
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A FAIR COMPARISON:
Regarding range and accuracy, the modern crossbow is
actually more similar to the modern high-performance compound bow.
Take a look at a popular 175# crossbow (Horton Legend HD)
vs. a 70# top-of-the-line compound bow (Bowtech Allegiance).
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Crossbow
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Arrow Mass: 420 Grains |
|
Max Speed: 305 fps |
ENERGY OUTPUT
KE = mv²/450240
KE = (420)(305²)/450240
KE = 39070500/450240
KE = 86.78 ft-lbs.
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|
|
Arrow Mass: 350 Grains |
|
Max Speed: 335 fps |
|
ENERGY OUTPUT
KE = mv²/450240
KE = (350)(335²)/450240
KE = 39278750/450240
KE = 87.24 ft-lbs.
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Compound Bow
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As you can see, the outputs of these
two weapons are similar. Of course, not many compound bows are as fast
as the Bowtech Allegiance, and some crossbows are even faster than the
Horton Legend HD175. Yet the point remains the same, a crossbow's
output is much closer to that of a modern compound bow than it is to any
type of gun.
LENGTH OF THE POWERSTROKE: Crossbows generally come in much
heavier draw weights (usually 150-185#) than compound bows. So it would
be logical to assume that more power-in means more
power-out. But wait! If you remember the work=force x
distance formula from your High School Physics class, you know
that how far is just as important as how hard.
Crossbows have a comparatively short powerstroke (the distance the bow's
string is drawn back). Most crossbows have only a 10-14" long
powerstroke vs. a men's compound bow which typically has a 18-23" long
powerstroke. So while the crossbow stores up more energy per-inch of
powerstroke (because of the heavier draw weights), the compound bow
makes up for it by drawing back a lighter weight, but over a longer
distance.
EFFECTIVE HUNTING RANGE: Much like a high-power compound bow, a
modern crossbow can easily launch an arrow (bolt) more than 1000 feet.
Under the right circumstances, that projectile could still be lethal at
the end of that range. Unfortunately, firing a crossbow up into the air
isn't a very effective way to hunt, nor could anyone accurately predict
where such an arrow would land. So maximum launch distance really has
nothing to do with determining your weapon's "effective hunting range".
An effective hunting range is the maximum distance that
you can reliably use your weapon to accurately, humanely, and
ethically harvest big-game. The answer isn't absolute (for any weapon),
as shooter skill-level and hunting conditions must be factored-in as
well.
YOUR SKILL & ETHICAL STANDARDS: Ultimately, the final answer is
up to YOU. A crossbow bolt is surely lethal at 50, 75, perhaps even
100+ yards, but only if you can control it. With a little
practice, an average crossbow shooter will be able to place shots
accurately out to 30 or 40 yards with little regard for loss of arrow
trajectory, changes in ground elevation, or compensation for wind
conditions. But if you expand that range to 75 or 100 yards, precision
becomes much more difficult, and you'll need extraordinary skills to
reliably control your shot-placement. So if you're new to crossbow
shooting, you may find that your first season's effective hunting
range is only 30 yards, but with repeated practice you may be
able to expand that range to 40 or 50 yards (or more). The bottom line
is....as a responsible bowhunter, it's up to YOU to decide when to
shoot and when not to shoot. You must set your
own ethical standards, based of the limitations of your skill and your
equipment. It's up to YOU to make good choices in the field, and never
risk missing or wounding an animal.
HARVESTING BIG GAME: Hunting with your crossbow comes with many
of the same challenges and rewards as hunting with a compound bow.
You'll still need to get in close, you'll still need to wait for a clear
broadside or quartering-away shot, and you'll need to place your shots
precisely behind the shoulder. And like every bowhunter, you'll hope
for a clean pass-thru and a good blood-trail for a quick recovery. Your
new crossbow will provide you with sufficient power to harvest any North
American big-game species. And with good broadhead selection and
perhaps a little luck, your new crossbow will surely put meat on the
table. But your ultimate success or failure will pivot on your ability
to use your weapon in conjunction with your wits.
INDUSTRY RATINGS FOR CROSSBOW SPEEDS: While you're shopping for
your new crossbow, here are a few final things to consider. Some
crossbows are advertised with rather impressive "test" speeds. But
beware.....a crossbow's actual arrow velocity is all
relative, particularly with regards to the arrow's total weight and
testing methodology. Light arrows (bolts) go faster - heavier arrows go
slower. That's the way it is with any bow (crossbow, compound, or
traditional). Unfortunately, crossbow
manufacturers do not necessarily follow the same testing standards when
it comes to rating their crossbows for speed. Some manufacturers
clearly state how their arrow speed data is obtained, others do not.
In fact, there is no clear "industry standard" for providing an
apples-to-apples comparison among the various crossbow manufacturers -
like we see with compound bows and
IBO Speeds. It's up to the individual crossbow manufacturer to rate
their own bows by their own methods. And since SPEED SELLS, some
crossbow manufacturers may try to gain an advantage by advertising
ridiculously optimistic speeds - speeds which might be impossible to
reproduce with a typical 420 grain bolt.
AFFECT OF ARROW MASS ON ARROW VELOCITY: If your new
crossbow is capable of launching a 420 grain arrow @ an honest 305 fps,
then it's possible to estimate the speed you'll get with a lighter or
heavier arrow. If we assume the bow's total KE output remains
constant, we can use our archer's KE formula (KE = mv²/450240) to find
arrow velocity given a known arrow mass.
KNOWN
420 Grains @ 305 FPS
ENERGY OUTPUT
KE = mv²/450240
KE = (420)(305²)/450240
KE = 39070500/450240
KE = 86.78 ft-lbs. |
PREDICTED
50 Grains LIGHTER BOLT
SOLVE FOR V
86.78 = 370v²/450240
370v² = 39071827
v² = 105599.53
v = 324.96 FPS
20 FPS
INCREASE |
PREDICTED
50 Grains
HEAVIER BOLT
SOLVE FOR V
86.78 = 470v²/450240
470v² = 39071827
v² = 83131.546
v = 288.33 FPS
17 FPS
DECREASE |
For the record, heavier arrows
(bolts) tend to make bows slightly more efficient, lighter arrows
(bolts) tend to make bows slightly less efficient. So our original
assumption that "KE output remains constant" isn't perfectly sound.
However, we'll not attempt to split that hair here. For the
purposes of this illustration, the difference would be negligible.
SELECTING A CROSSBOW BOLT: Obviously lighter bolts fly
faster. But before you choose the lightest bolt you can find,
there a few things you should consider.
Most crossbow manufacturers specifically recommend a minimum grain
weight bolt for use in their various crossbow models. We strongly
recommend you follow these guidelines. Shooting
underweight arrows (bolts) puts your bow's components under considerable
stress. In addition, shooting underweight arrows may void your
factory warranty and put you at risk of personal injury - should a limb,
string, or other bow component fail. Remember that faster isn't
always better. You may find you'll achieve better broadhead flight
and overall control when shooting more moderate speeds. It's also
worth noting that heavier bolts will make your crossbow quieter and will
prolong the life of your string and cables.
CROSSBOW BUYER HELP
1. View
Main Crossbow Page
2.
View All Crossbow
Specifications
3. View Crossbow
Accessories
4. Assembly - What to Expect
5. Field
Performance - What to Expect
6. Cocking the Bow -
Things to Consider
7. State Crossbow Regulations |
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340 Low Gap Fork * Oil Springs, KY 41238 *
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