Archive for January, 2011

0 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 5 (0 votes, average: 0.00 out of 5)
You need to be a registered member to rate this post.
Loading...

Published by archerchick on 05 Jan 2011

Calculating Kinetic Energy and Momentum


BOWHUNTING WORLD
October 2006

we receive many questions about figuring kinetic energy and
momentum in arrows. Below is information about the formulas for calculating kinetic energy and momentum, their relationship, and the derivation of these formulas. There are only two basic
formulas: one for kinetic energy and one for momentum, although there are
probably many ways to write them. Each formula has several constants that are required to make them usable in a form where the values are expressed in terms we are familiar with. Conversion to grains for the arrows and from the British gravitational units of poundals to pounds-mass are a part of that.

Determining An Arrow’s
Kinetic Energy
The basic formula for kinetic energy is:

To use the weight of the arrow in grains, Our usual unit of measurement, it is neccessary to convert from poundaIs to grains
in the formuIa, therefore:

Note: The acceleration of gravity
(g) varies with latitude. As latitude increases, “g” also increases. 32.16 feet
per second per second corresponds to about 40 degrees latitude, which is a
reasonably good average for the United States. Gravitational pull is higher at the
poles.

Therefore:

Dimensionally masses are measured
in poundals and velocities in feet per second. A poundal is defined as the
force which, if applied to the standard pound body, would give that body an
acceleration of one foot per second per second. One poundal equals 1 /3 2. 1 740
pound-force (lbf). These dimensions are stated in the British “absolute system” in which the basic dimensional units are: one poundal, one foot, and one second. Therefore, the basic unit of
momentum is one poundal-second.

When momentum is expressed in the British gravitational system (the system in most common use in the United States), the basic unit is one pound-second. One pound-second is equivalent
to 32.1740 poundal-seconds. Work or energy is expressed in foot- pounds in the British “gravitational system,” or as foot-poundals in the British “absolute system.” Again, the acceleration of gravity enters the picture so that: one foot-pound = 32.1740 foot-poundals.

Unfortunately the term “pound” is used ambiguously to define both “force”
and “mass” in most instances. To distinguish between these two usages, the term “pound- force” was coined to apply to the pound when it is used to express force, and the term “pound-mass” was designated to apply to pound when it is used to indicate mass.
Simply stated:
“A load that produces a vertically downward force because of the influence of gravity acting on a mass may be expressed in ‘mass’ units. Any other load is expressed in ‘force’ units.”
The kinetic energy of an arrow in flight is a function of its mass and velocity squared, as shown in the formula outlined above. It has the dimension of foot-pounds. The momentum of the same arrow is also a function of its mass and the single power of its velocity. Momentum
has the dimensions of foot»seconds. The difference between kinetic energy and momentum is a function of the velocity divided by 2 and, of course, the change in dimensions from foot-pounds to
pound-seconds. lf kinetic energy of the arrow is divided by “v/2,” then the result
is the momentum of the arrow. For example: An arrow with a weight of 450 grains and a velocity of 230 feet per second will have a kinetic energy of 52.8718 foot-pounds.
Dividing 230 by 2 yields 115. Dividing
52.8718 by 115 gives a momentum of
0.4598 pound-seconds.

To calculate momentum directly the following formula can be used:
momentum = wav/225120 Ib.-secs. 1
wa is arrow weight in grains {
v is arrow velocity in feet per second. y
For example: An arrow with a weight Y
of 450 grains and a velocity of 230 feet per
y second will have momentum equal to:
450 x 250/225120 = 0.4598 pound-seconds.
To Calculate momentum directly the following formula can be used.

Archived By
www.ARCHERYTALK.com
All Rights Reserved

0 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 5 (0 votes, average: 0.00 out of 5)
You need to be a registered member to rate this post.
Loading...

Published by archerchick on 05 Jan 2011

Fun With Draw Length ~By Richard Combs

BOWHUNTING WORLD
October 2006

Home Bow Mechanic- Fun With Draw Length
by Richard Combs

Archers are often advised to let their sight pins “float,” or wander over ,
the bull’s-eye, and let the precise moment of release come as a surprise.
The subconscious, or so goes the theory, is constantly attempting to center the
sights on the target, and any conscious attempt to center the sights or time the
release will result in flinching, punching the release, target panic, or other accuracy-robbing problems.

This approach works very well for a great many bowhunters, but it is based on
the major assumption that it is impossible to hold a bow steady. Bowhunters are not machines, of course, and holding a bow immobile for any period of time, shot after shot, probably is impossible. On the other hand, it is certainly possible to hold a bow steady for short periods, or (if
you can’t buy the notion of complete steadiness, to at least minimize the size
of the wobble. Look at it however you like, but holding a bow steadier is a very good thing for accuracy.

A major factor in that steadiness is correct draw length. lf you find that you have a difficult time keeping your sight pin on a 3-inch bull’s-eye at 20 yards, and if you are not pulling a draw weight that is too heavy for you, there is a very good chance that the problem is incorrect draw length. More often than not, incorrect draw length means a draw length that is too long. The conventional explanation for this is that archers tend to stretch their draw lengths to get greater speeds. As a general rule, one additional inch in draw length generates almost 10 fps in arrow speed. Competitive 3-D shooters, in particular, often attempt to maximize speed to flatten trajectory, and even bowhunters who do not shoot 3-D competitively have been influenced by those who do.

No doubt there is some truth to all this, but over the years I’ve observed that beginning bowhunters, including those who have only a vague idea what 3-D shooting is all about and who are unaware of the relation between draw length and arrow speed, still have a strong tendency to shoot at excessively long draw lengths. For whatever reason, selecting the correct draw length
seems to be a learned and even slightly unnatural thing.

A long overdue trend in recent years has been to back off on draw length.
With today’s more efficient bows, many bowhunters-and some 3-D shooters—
have discovered that they can achieve as much speed as they want without resorting to longer draw lengths. In any case, smart hunters have always been willing to trade a little speed for greater accuracy. While it is certainly possible to over compensate and move to a draw length
that is a little too short, most top shooters agree that a too short draw length is
preferable to a too long one. How critical is it to achieve precision in draw length? The better shots of my acquaintance, including the most serious 3-D competitors, have a draw length tolerance of
a quarter-inch. Anything shorter or longer than that is immediately noticeable, and they will make adjustments.

Draw Length And Draw Weight
Holding the bow steadier is not the only reason the correct draw length is
important. We mal<e reference to draw length and draw weight as separate characteristics—-which they are—but they are not unrelated. It shouldn’t be surprising that the same draw weight will
be perceived differently at different draw lengths. imagine holding your bow at full draw from a position as far back as you can reach. A draw length that is too long increases the difficulty of holding the weight comfortably, which is one reason the bow is more difficult to hold steady at longer draw lengths. The difference is less noticeable in the case of a too short draw length, but holding bow at full draw from a position in front of the optimum anchor point is also
more difficult. And either position can increase the likelihood of the arm or shoulder problems that plague too many bowhunters.
Perceived draw weight aside, it is difficult to achieve proper and consistent shooting form outside the parameters of correct draw length is a much greater tendency for the string to slap the bow arm. For purely anatomical reasons, this can be a chronic problem for some bowhunters, but excessive draw length is often a major factor. For years I watched a hunting buddy struggle with the problem. He bought custom grips, purchased bows with very high brace heights, modified his stance to an extremely open position, and experimented with some difficult and unusual shooting forms. Finally he tried a draw length that was nearly two inches shorter and the problem disappeared.

Among the more pernicious inconsistencies in shooting form is the tendency to creep forward from the wall before release. Pros have come up with all sorts of antidotes to this, including creep tuning and stops on rests and cams. Clearly incorrect draw length will magnify the problem. Not only is it initially less comfortable to hold a bow at full draw when draw length is off, but the arm, shoulder, and back become fatigued more quickly at improper draw lengths. Fatigue is a major factor in creep.

WHEN THE RIGHT DRAW LENGTH IS WRONG
You might assume that draw length is draw length – that if your optimum draw length is 28 inches on one bow, then it should be 28 inches on any bow. That is conventional thinking, but the folks at Spot-Hogg are not very good at thinking conventionally, and as they so often do, they have a different idea. As Spot-Hogg’s Cabe Johnson recently observed, differences in axle-to-axle length can make a significant difference in optimum draw length. The reason is that shorter bows have a more acute string angle at full draw than do longer bows.

Assume for instance, that you draw your string back to touch the tip of your nose at full draw, with two bows one short and one long. The distance between grip and nock point may be the same on both bows, but the distance between the riser and the string where it touches the nose will be different because of the different string angles. The tendency will be to change the shooting form to compensate- to modify the head angle, change the anchor point, extend or bend the bow arm
more. Those adjustments will probably decrease the ability to hold the bow steady and increase discomfort, not to mention reinforce inconsistencies in shooting form. The bottom line is that,
contrary to conventional thinking, there is no “right” draw length for a given individual. The optimum draw length will depend in part on the bow.

Adjust Draw
Many—though by no means all—compound bow designs offer a range of draw length adjustment accomplished by moving the end of the string to one of several different posts on the cam. Often
the range is three inches, with changes in half-inch increments. With other bows, changing draw length requires changing modules on the cam. However these adjustments are made, they may
have slight effects on let off or bow efficiency, but any loss in these areas will be more than compensated for by the advantages of shooting at the correct draw length. In most cases the bow will have to be pressed to make these changes. Changing draw length will usually require that the bow be returned. (In some cases, simply pressing the bow will require that it be returned.)
For more precise adjustments, strings or cables can be shortened by twisting. Lengthening the string lengthens the draw, and shortening the string shortens it.

The opposite is true for cables:Lengthening cables shortens the draw and vice-versa. Manufacturers of modern, high quality strings usually warn against shortening a string more than a quarter inch or so by twisting, but usually this is enough, especially if done in conjunction with moving the end loop
to another post, or changing modules. One way to reduce the number of twists necessary to accomplish the desired change is to adjust both strings and cables. To shorten the draw length, for
instance, untwist the cable a few turns, then twist the string a few turns.

Draw Length Alternatives
Repeatedly pressing the bow and making adjustments until the precise draw length is arrived at can be a frustrating and time-consuming affair, and not every bowhunter owns a press. Fortunately, there are better ways to experiment with draw length. For starters, the length of many release aids can be adjusted. Almost all wrist caliper releases are easily adjusted. You might object that adjusting the release aid is not really changing draw length, and you would be correct. Shortening the length of a release aid does move the anchor point forward, though. In fact, it accomplishes
all the objectives of shortening the draw length, without the disadvantage of reducing arrow speed. I’m all in favor of maintaining, or even increasing, arrow
speed if it can be done without a downside. ln effect, achieving the proper
anchor point without shortening the power stroke of the bow is a free lunch.
The only caveat, of course, is that the release itself should not be uncomfortably short. Many bowhunters touch the trigger with their fingertips anyway, which is not the best form. In that case,
shortening the release aid is a “twofer,” providing a better anchor point and a positioning of the finger on the trigger that is less likely to contribute to punching the release or even target panic.

Some bowhunters looking for extra 10 fps or so of speed might find that by shortening their release aid, they can actually extend their draw length without changing their anchor point. Don’t need an extra 10fps of speed? Shorten the release aid, extend the draw length, and back off on the draw weight by five or six pounds. Speed will be about the same, but you’ll be pulling and holding significantly less weight.

Bowhunters who feel that their release aid is already as short as it should be can switch to a forward trigger design release. By using a release aid with a trigger farther forward, and much closer to the jaws of the release, it is possible to shorten the release without changing the position of the trigger relative to the wrist caliper to another to another shorter style of release aid.

A similar option is to alter the size of the string loop. (If you’re not using a string loop, you should be) As with the release aid making the loop shorter will move the anchor point farther forward, while making it longer will move it back. If a longer loop makes for a better anchor point, then lengthen the draw length by changing string posts or modules, or by untwisting the string a few turns then shorten the loop. Perceived draw length will be unchanged, but real draw length will be longer with a longer power stroke and more speed.

Finally, bowhunters shouldn’t overlook the effect of grip on draw length.
We’re talking an optimum range of quarter inch in draw length for most shooters. The difference between a wrist high grip, in which the riser touches only a small bit of skin between the thumb and forefinger, and a low grip, in which it is in contact with much of the hand, can easily make a difference of half an inch.

Archived By
www.ARCHERYTALK.com
All Rights Reserved

0 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 5 (0 votes, average: 0.00 out of 5)
You need to be a registered member to rate this post.
Loading...

Published by archerchick on 05 Jan 2011

Western Deer -Double Header ~By Brandon Ray


Bowhunting World
October 2002
Western Deer Double-Header
High Plains River bottoms Offer the Best Of Both Worlds In Trophy Whitetail And Mule Deer Hunting

Which do you prefer, Coke or Pepsi? Ford or Chevy? Realtree or Mossy Oak?
When it comes to hunting deer in many western states, you’ll face a similar selection dilemma, Whitetails or Mule Deer?

In many western states a deer tag is good for one buck of either species, but not both. Before you make a decision on which species to target, consider the landscape and the hunting tactics that work best. Time of year is another important factor.
Story and Photos by Brandon Ray

Over the past two hunting seasons I’ve had the good fortune to draw deer
tags in eastern Colorado and eastern Wyoming. The landscape is very similar in
both locations. Cottonwood trees with trunks as big around as tractor tires follow the course
of small creeks and rivers across the eastern plains of both of these western states. Head-high willows and Russian olive trees crowd the banks of the waterways even more. But
these life—giving riparian zones are surrounded by endless miles of rolling hills, fragrant sage
and yellow grasses that wave constantly in a strong western breeze.

For the most part, whitetails thrive along the river beneath the tall trees while the mulies do
just fine in the open sage and steep coulees. Tagging a whitetail in the brushy river bottoms
calls for stand hunting. During the November rut, calling and rattling will increase your
chances. lust a couple hundred yards away from the towering cottonwoods, spot and stalk
is the best technique to arrow a big mule deer in the open. Ultimately the question is: would you
rather sit and wait or make something happen?

In November, 2000 I decided to focus on rutting whitetails in eastern Colorado with the
help of outfitter Chris Cassidy at Alpine Outfitters. Less than one year later, in September of 2001, the focus would shift to wide-racked mule deer in eastern Wyoming. My host for that trip,
Jimmy Fontenot of Wildlife Connections, assured me that early season was a great time to shoot a big mule deer with a bow. Pleasant weather and seeing lots of bucks in the open sold me on the September dates. Both hunts proved that western deer hunting can offer something for any deer hunter.

WESTERN
WHITETAILS
The 2000 season marked my third year to bowhunt whitetails on Colorados eastern
plains with outfitter Chris Cassidy. Cassidy leases some prime properties on the plains and
he specializes in helping bowhunters score on big whitetails. I asked Cassidy, a man with 13
years of experience hunting Colorado`s plains for his advice on how to bow—kill a big whitetail in a western river bottom setting. “Hunting from treestands during the rut the first few weeks in November, is by far the best way to score. The bucks move into the river bottoms in search of does during the rut. This concentrates them a little more as they come in and move up and down the river corridors looking for receptive does.” Each year Cassidy limits the harvest of mature bucks on his ranches and encourages his clients to pass up younger bucks to let them reach their full potential. It’s a plan that pays off every year. Cassidy’s success with bowhunters on the plains runs right at 75 percent. with near 100 percent shot opportunities. Most of the bucks his clients shoot measure 135 inches or more. The biggest buck taken in recent years scored over 170 inches.

My November. 2000 Colorado whitetail hunt ended the same day it began. As good as that sounds, the hunt was far from easy. l spent about 12 hours in a treestand overlooking several well—worn trails before punching my arrow into a behemoth—sized buck in the waning minutes of last light. The waiting was made even more challenging because of the numbing cold. When l got on stand before sunrise the temperature was 10 degrees below zero. The warmest it got all day was 10 above zero. While the temperatures were bone-chilling, the rut was in full swing. Throughout the
day l watched several bucks chase does through the crunchy snow near my stand.

Late in the day. when l was about to climb down from my stand. I noticed movement to the south. A good buck was crossing a creek, but well out of bow range. l grabbed the grunt call, chipped the ice from inside the plastic mouthpiece and began giunting. loud. At first l couldn’t see the buck in the trees to even know if he had heard the sound, but then he appeared on my side of the creek, 150 yards away, staring in my direction. I let out another chorus of three deep grunts. He was coming my way. At 60 yards he passed behind a cluster of trees and I seized the chance to raise my binoculars and study his rack again. I could count 10 points. I dropped the binoculars and clamped
my release onto the bowstring. At 30 yards I jerked my bow to full power. He stopped for an instant, then started to walk again just as I let the arrow go. The arrow impacted with a loud CRACK! I watched through my binoculars as the 250-pound 10-point took a few steps, then slumped into the snow.

Stand hunting during the rut is a very effective whitetail tactic in any western river bottom. Set up stands in travel corridors and areas with lots of buck sign, scrapes and rubs, and be patient. Be prepared for long days and very cold temperatures and pack a grunt call and rattling horns to lure out-of—range bucks closer to your stand. That very tactic helped me arrow my personal best bow whitetail.

PRAIRIE MULE DEER
Outfitter Jimmy Fontenot has been guiding mule deer hunters in eastern Wyoming for the
past eight years on a 65,000—acre ranch. In those years of guiding, Fontenot’s bow clients
have experienced 100 percent shooting opportunities, and only one archer has left the
ranch without taking a buck. “A realistic goal for archers on my hunt is a buck scoring between 140 and 150 inches. A patient hunter might get a chance at a much bigger buck. Our biggest bow-killed buck scored about 180 inches.

“Optics are everything on this hunt. We start each morning glassing from the vehicle or a high vantage point. I like glassing from the truck at tirst light because it allows us to move quickly and cover more ground than if we were on foot. Once a buck is spotted we will watch him hed down then try a stalk. In the evenings we watch bucks come out of the ravines and coulees, then try to use
cover or breaks in the land to get close enough for a shot. On good days an archer will get one stalk in the morning and another in the afternoon.”

The first day of my September, 2001. Wyoming mule deer hunt was as good a of hunting as you could ask for. I saw 33 bucks ranging in size from young fork horns to a couple of Wide 4x4s that would make any archer drool. Early season means bucks are usually in bachelor groups and they are not nearly as spooky as they become later in the season. The bunched-up bucks are easy to
spot, spending lots of time in the open, but they are tough to stalk. Late in the afternoon
l attempted a stalk on a symmetrical 4×4 that we guessed would score about 160 inches,
but he was accompanied by six other bucks and I never got closer than 100 yards.

At noon on the second day of my hunt I learned a valuable lesson. You can’t shoot a
big buck if your bow is in the truck. Sounds simple, right’? Here’s what happened. From one of the main ranch roads l spotted a respectable 3×3 buck bedded in the shade of a row of willow trees. The tall willows lined a shallow ditch and provided the only cover for a quarter mile. The buck under the willows was too small to shoot this early in the hunt. but I decided to loop around with my camera and take some photos.

When I belly crawled through the sage and up to the lip of the ditch I got an unexpected surprise. Bedded less than 20 yards away and staring right at me was the same big -4×4 buck from the previous afternoon!
He was lying in a shallow depression that we couldn’t see from the road. I was aimed with only a telephoto lens and the buck obviously knew that. He stood for one long minute then casually walked out to about 40 yards and stood next to the 3×3 buck. I cranked-off a roll of film at both bucks. but wished for my Mathews bow instead of my Canon camera.

Finally. the two bucks galloped across the prairie. I spent most of the afternoon trying to
re-stalk that buck. but he was super alert and I never got within range. Lesson: Even if you
can see only one bedded buck, chances are good that during he early season he’ll have
at least one partner with him.

Late in the afternoon on day three I got a second look at old white-faced 4X4 buck
in a dark ravine. l passed this same buck on the first morning. but decided now that he
was plenty big enough. A short stalk and one long bow shot later and my tag was filled.
This time the camera stayed in the truck during the stalk and I was all business! The
buck’s live weight was about 225 pounds and his yellow-colored rack sported shreds
of dried velvet dangling off the beams. The date was September l7.

Western prairies might seem bleak and lifeless at first glance. with barely enough
cover to hide a jackrabbit. but find a stretch of tall trees and shallow water winding
across these plains and you`ll likely find bowhunting gold. Whether your passion is
rutting whitetails or early season mule deer, western waterways have something for
every bowhunter. The toughest part is deciding which species to hunt.

Archived By
www.ARCHERYTALK.com
All Rights Reserved

1 vote, average: 5.00 out of 51 vote, average: 5.00 out of 51 vote, average: 5.00 out of 51 vote, average: 5.00 out of 51 vote, average: 5.00 out of 5 (1 votes, average: 5.00 out of 5)
You need to be a registered member to rate this post.
Loading...

Published by chip1964 on 03 Jan 2011

New Laser Broadhead

I have seen this hollow point laser broadhead first hand and believe it will be the most amazing bow hunting innovation in the last 10+ years! It will help all bow hunters become more accurate shooters at standard and especially at long range shooting of 60-80 yards! It will also greatly improve the accuracy and ability to shoot in low-light conditions at dawn & dusk in true hunting conditions. I am very excited to see industry improvements like clean-shot to help bow hunters shoot more accurately! I can’t wait to purchase a pack at the ATA Show in Indy this week!

0 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 5 (0 votes, average: 0.00 out of 5)
You need to be a registered member to rate this post.
Loading...

Published by Ryan Grand Pre on 02 Jan 2011

Late 60s Early 70s Fred Bear Kodiak Special Compound Bow

I have a fred Bear Kodiak Special Compound Bow That was made in Grayling, Michigan late 60s Earliy 70s. Need to know what it is worth?? any idea would help.

0 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 50 votes, average: 0.00 out of 5 (0 votes, average: 0.00 out of 5)
You need to be a registered member to rate this post.
Loading...

Published by getaway84@live.com on 02 Jan 2011

rage

i have heard from many people that u cant take a bad shot with a rage broadhead because it will not open up.  just last night i shot a doe looking at me quartering a little and blew right though the shoulder blade.  didnt run more than 60yrds and crashed.  so for all u none believers i have to say u r full of it i wont shoot anything else

1 vote, average: 5.00 out of 51 vote, average: 5.00 out of 51 vote, average: 5.00 out of 51 vote, average: 5.00 out of 51 vote, average: 5.00 out of 5 (1 votes, average: 5.00 out of 5)
You need to be a registered member to rate this post.
Loading...

Published by Clean-Shot on 01 Jan 2011

Spot-On (The Ultimate Evolution of Broadheads)

This new line of hunting broadheads from Clean-Shot Archery will be launched at the 2011 ATA Trade Show next week. The Spot-On Laser Broadhead is automatically activated with a simple bow mounted magnet. As soon as you pull back to full draw, the laser turns on and shows you the exact impact point of the arrow. It can be adjusted in elevation (up to 24″ at 30 yards) to allow the end user to fine tune the laser dot placement on the target. The battery is rechargeable with a separate 12 volt charger, and you will get up to 100 (4 second) shots with each charge. Come see us at the ATA show (booth IZ-15) of visit our website at www.clean-shot.com

 

Bad Behavior has blocked 925 access attempts in the last 7 days.