Category Archives: Archery

Bowhunting and Kinetic Energy

Posted on August 10, 2011 by cintaduapuluh

You bring your bow out into the yard for some target practice. You’re shooting at the bulls-eye and putting 3 arrows inside of a 3 inch circle. Your speed is phenomenal. It’s like as soon as you pull the trigger the bow has passed 40 yards and placed itself into the target in the same millisecond. You can’t believe the speed you’re getting, but there is one problem, the arrow is not penetrating deep enough into the Styrofoam. Heck, your arrow could perhaps bounce off a deer. What seems to be the problem though? The chronograph recorded you at a blistering 297fps. I’ll tell you what the problem is, lack of kinetic energy.

Everyone is so caught up in the speed game. People are overbowing their bows, pulling their draw length back 1-3 inches too long for them, using arrows so light they might as well dry fire their bows. What they do not see, is that kinetic energy is what kills deer, not speed. Yeah, so you’re shooting nearly 300fps with a full set up, but do you really think that means that a deer still can’t jump your string? Speed is important, very important, but not as important as the kinetic energy you’re shooting.

So what is “kinetic energy?” Kinetic energy basically means the amount of penetration your bow is going to produce at a certain arrow velocity. To measure the amount of kinetic energy your bow is shooting, the formula is: speed * speed * arrow weight / 450240. You can see the importance of speed in the formula, but the most under looked aspect in the formula is the arrow weight. IBO recommends you shoot 5 grains of arrow weight for every pound of draw weight, but that is for maximum speed standards and is basically dry firing your bow. You need about 6-8 grains of arrow weight for every pound of draw weight. Yes, this will slow you down a slight bit, about 1fps worth for every 3 grains of arrow weight, but you will gain what is really important: kinetic energy.

There are calculators on the computer that will help you determine your speed and kinetic energy if you do not have access to a chronograph, but the easiest method to determine at home is simply know the IBO standards, which is 30 inches of draw length, 70 pounds of draw weight, and a 350 grain arrow. If your bow does not reach a 30 inch draw or 70 pounds of weight, then use the maximum weight/length your bow comes in and times the draw weight by 5 to determine the total grain arrow used. So if you’re using a bow that has an IBO of 335 fps: subtract 10 fps for every inch of draw length lost, subtract 2 fps for every lb of draw weight lost, subtract 1fps for every 3 grains of arrow weight lost, and that should tell your your speed, give or take 5 fps or so.

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The Barnett Predator A Powerful Crossbow

Posted on July 12, 2011 by cintaduapuluh

Hunters and hobbyist who are looking for a more powerful crossbow should seriously consider the Barnett Predator 18035 Crossbow. This crossbow made by Barnett can be considered the most powerful among all crossbows that they have produced. Its power is further complemented by its durability which assures its user that it can be used for hours of hunting.

The Barnett Predator 18035 Crossbow can shoot arrows at speed of 375 feet per second. This speed is good enough to hit long range targets. The ability of the crossbow to fire bolts at this speed is because of its foot stirrup; a feature that increases the draw weight up to 175 pounds.

If you are new to hunting and you need to use a comfortable crossbow, then the Barnett Predator 18035 is the one for you. It has an adjustable stock and cheek piece so you can customize the crossbow to make the hunting experience more comfortable for you. Its rugged, durable and lightweight magnesium riser adds more comfort while using the crossbow.

Most novice hunters usually get bothered by the vibration of a crossbow. These vibrations can affect your accuracy and may cause you to miss your target. Luckily, the Barnett Predator 18035 comes with the Anti-Vibration Isolator (AVI) feature. This feature cuts down the vibration of the crossbow and reduces its noise footprint. With this feature, you can be as efficient and as accurate as most experienced hunters.

This crossbow can also be easily used by people who are used to holding pistols and guns. It has a pistol-type grip and machine triggered pull which can make shooting a crossbow as easy as shooting with a gun. Combined with a high-velocity cam and a great cable system, the Barnett Predator 18035 was made for ease of use and comfort.

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Strength and Spine of Carbon Arrows

Posted on December 3, 2010 by cintaduapuluh

The shaft and spine of carbon arrows are a very important addition to successful bowhunting. The “shaft” of the arrow is also known as the GPI or “grains per inch” on the bow. If you look in small letters, you’ll see something like “7.3 GPI” or “9.5 GPI” or something greater or less. That is the grains per inch of the arrow you’re using and has significant affects on the performance and results of your bow.

The smaller the shaft, the faster the bow will be; however, it will also mean the bow will produce less kinetic energy and the result is less penetration. If you take a small gravel and throw it against a fence, it will be quick. Sometimes, even so quick you won’t see the gravel moving, but you will only hear a “peck” noise. If you would grab a much bigger rock, it might travel a little slower, but you will hear a much heavier “bang.” That is because the heavier the rock, the more kinetic energy produced. Don’t get caught up in too much speed. Kinetic energy is very important.

Kinetic energy is probably the most under-looked factor by archers to this day. Everyone is so caught up in how fast the chronograph measures their bow, that they lose the idea on how much penetration and kinetic energy the arrow is producing. In boxing, kinetic energy leads to knock outs, while speed leads to points.

Kinetic energy is measured in pounds per foot. And the formula to finding the kinetic energy your bow is generating is [speed * speed * arrow weight divided by 450240]. That’s to say that speed is important for your total kinetic energy produced, but the arrow weight is also important. You want to produce fast speeds with a heavier grain arrow. Most people that are not seeing a lot of kinetic energy is due to lack of arrow weight; rather than lack of speed.

People often mistake the “spine” of the arrow to be the grain. The “spine” is the big number on the arrow often written “500″ or “340″ or “400″ or somewhat. The heavier your draw weight, the lower the “spine” number should be. The spine number is nothing more than the total bend-stiffness ratio. The technique used to determine the “spine” of an arrow is to take a 29 inch arrow, hold it at 28 inches on each end and hold a 1.94 pound weight in the middle of it, the amount of bend determines the stiffness. A heavier draw weight arrow would have a harder landing and more impact, and the result is the need for less bend in the arrow, so that the arrow doesn’t break or bend upon impact.

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How To Make Your Personal Bow And Arrow

Posted on November 17, 2010 by cintaduapuluh

Many people who love archery would like to create their own bow and arrow. In order for us to make one, we also need a little planning. If we make a plan, we can create a better bow and arrow. In order for us to make an archery equipment, we need to have a piece of wood, arrow heads, sandpaper, string, grip, cloth tape, shaft, fins, small hand saw, and a glue gun. One way to create a perfect tool is to examine the real thing. Below are some of the instructions that we can follow.

1. Be sure to choose a wood that is flexible enough. Some of the wood that are commonly used in making the bow include mulberry, bamboo, oak, lemon tree, black locusts, hickory, and teak. It is much easier to cut and clean a wood that is still young compared to the hardened wood. Try to search for an archery store and examine the bow. Check how heavy and soft the surface of the wood.

2. Now that we have an idea about how to make the bow, then we can use the information that we saw from the local store. Be sure to choose a wood that also bends properly, otherwise it will not be a perfect bow. Almost every wood material tends to bend, choose the one that has the right bend. Cut the wood using the small hand saw.

3. In order to make the bow a strong one, make sure that the center or the grip is thick enough. We can also shave off both ends of the bow using a knife or a carving tool. The center should be thick, and the end segments should be more flexible. Use the sandpaper to refine the carved ends of the bow.

4. After finishing the bow, we can start preparing the notches. Make sure to give allowance on the measurement of the notch and not exactly on the length of the bow. We will use the excess notches on both ends of the bow. Strings are often made from different materials like nylon, hemp cord, rawhide, sinew or fishing line. Make sure that as we connect the string to the bow it does not stretch too much.

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