Arrows

[Kody94]

I've been real happy with Easton ST Axis Obsessions. They are extremely durable.

[Bow Walker]

I do agree bow walker that the shooting is part me being rusty but ever since I bought the bow I never had hit shot the way I would like it to yet the bow I had before I could shoot realy well. I have had both boorman and specialty shooting sport set up my bow seem not to mater who sets it up. it a comfort factor with the bow i have now for some reason it felt good in the store but now that i have owned and shot it I am not that comfortable with it. becouse of the comfort ussue I did not bow hunt at all last year do to the fact the animal deserve more respect then just me going out and trying to hit it I want to know I can pick a hair or patch on that animal and know i will be close to that target. that why I thinking new bow

If that's the case - then definitely that bow is not for you. Once you 'lose confidence' in a piece of equipment it'll never perform up to your expectations. Yup - new/different bow in the future for you.

[Kudu]

This fletched sharpened lead pencil is a great example of the average hunting arrow in use today. It’s light weight and has a rather low FOC (Forward of Center) balance. Now imagine tossing this fletched pencil at the dartboard. It would appear to fly okay and because of its light weight, have a fairly flat trajectory. However, it wouldn’t hit the dart board with much force because of its light mass. Common sense would tell us if we want this pencil to strike with more force, we need to throw it faster. The higher velocity pencil strikes the dart board with much more authority but we find out because it’s low FOC, the shaft of the pencil doesn’t follow the point, making it unstable in flight. It may even strike the board sideways.

Light weight arrows with a low FOC are very much like this fletched pencil. They have a flat trajectory and are fast but have poor penetration because of low mass and unstable in flight. Whether the arrow shaft is made of carbon, aluminum or wood, like the pencil, it has the same amount of mass weight per inch and a point of fairly light weight. This type of arrow generally get the job done when everything goes right but if it encounter brush, bone or even thick hide and hair, it may not have enough mass/energy to push the broadhead to the vitals. If you shoot it from a fast bow you'll find that it's not very stable and like a fast, light, rifle bullet, it doesn't take much to deflect it off course. With the average 125 grain point on an arrow like this, the FOC is around 10%. Not bad, but not great. It takes game if everything goes right but it doesn't have much penetration. Light, fast arrows with low FOC are like this. They offer average performance at best.

Is heavier better? Not always.

The steel shaft of this nail is about four times heavier than the wooden lead pencil so its trajectory will not be as flat; however, because of the increased mass, it will hit the board with much more momentum and have greater penetration. This fletched nail is an example of a carbon or aluminum shaft with added internal weight tubes. It is important to understand that the weight is added equally to the entire length of the shaft . The total arrow mass has increased but unless you increase the point weight dramatically, the FOC doesn’t change. Now you're shooting an arrow that isn't any more stable in flight and relies almost totally on the mass of the arrow shaft to push the broadhead through game. The nail has an improved mass advantage over the pencil and therefore greater potential for improved penetration. It’s a good step up for bowhunting but still falls short of ideal arrow design.

Now take a look at the standard throwing dart. See how this tapered design has most its mass up front? The rear of shaft is light weight and only needs minimal fletching. Imagine throwing this dart at the board and see the difference over the pencil and nail. Its design has a heavy forward (FOC) portion that is actually pulling the shaft in its trajectory arc rather than the pencil and nail, which is a shaft that is pushing a point. Engineers will tell you that a pulling engine is much more efficient than pushing engine. Its flight is smooth and stable, therefore has much better accuracy and it hits the target with authority. Go ahead, throw it harder and faster. It still flies perfectly and makes a resounding 'thunk' when it hits the board.

What you need is an arrow that is very much like the throwing dart. Its design has a thicker, heavier and stronger forward end that tapers toward the rear. The front of the shaft gives it great strength right where we need it most, right behind the broadhead. Also, it should have a brass point insert which is 3 times heavier than the standard point inserts used in other arrow's.

Having all that mass weight toward the front not only gives the arrow a high FOC, we've built-in Extreme FOC (EFOC).

Why are airplanes designed with EFOC? Why are darts designed with EFOC? Because its a superior design for stable flight. There's no down side to shooting a tapered arrow with EFOC. It offers stable flight and near instant recovery from archer's paradox and impact vibrations. That means more energy retained by the arrow to deliver upon impact. In other words, more energy to blow through your animal no matter where they're hit.

Now, like the dart, the light tail end of the arrow simply follows as the extreme weight forward arrow pulls it not only through the air, but through thick hair, hide and bone.

Speaking of bone, the taper of the shaft gives us another penetration advantage. As the diameter of the shaft gets smaller, there's less friction against bone that might try to pinch the shaft. This reduces potential friction and allows more pass-throughs.

Typically in my "X Bow" I shoot a 750 grain arrow, tipped with a silver flame German kinetics, two blade broadhead - this package will take care of anything found in North America.

I guess you guys figured this all out along time ago anyway - so my post is generaly aimed at the newer guys on here.

..--..

[willyqbc]

Why are airplanes designed with EFOC? Why are darts designed with EFOC? Because its a superior design for stable flight. There's no down side to shooting a tapered arrow with EFOC. It offers stable flight and near instant recovery from archer's paradox and impact vibrations.

You're not comparing apples to apples here Kudu.....for the most part an airplane has constant forward thrust from just forward of the center of the plane, and a dart is thrown holding the front of the dart. Extreme FOC works well if the force is being applied directly to area where the bulk of the weight is. Imagine what would happen if you threw that same dart holding onto the very back of it.......the tip would rise or fall and your hand would go past the tip flipping it back and it would not fly at all. The problem with archery and using extreme FOC is that you actually increase arrow flex coming off the bow. Remembering our high school physics....."an object at rest tends to stay at rest".....the heavier the object the harder it is to get it moving, so as all the force of the draw cycle is being forced forward the front end weight resists moving and the arrow bends.....the heavier the front end, the more the arrow bends. I think rather than focusing on extreme FOC an archer or hunter needs to find the arrow spine and tip weight that is right for his or her bow, too much FOC can be as detrimental as too little in my opinion.
I wont get into the whole debate about heavy vs light arrows for hunting as it is an argument that is neverending in the archery world.

as always
Just my opinion
Chris

[The Hermit]

Best thread on this topic yet!!!

[Kudu]

You're not comparing apples to apples here Kudu..... The problem with archery and using extreme FOC is that you actually increase arrow flex coming off the bow.
Chris

Fair enough - I was not about to enter the debate on heavy verus light – in fact I never mentioned spines etc - those are all different subjects.

However, should one want to venture down this path ...........
　
How much FOC does one need?

The range of FOC recommended for different forms of archery varies. In their charts,Easton shows the following recommended FOC ranges, with calculations based on the AMO Standard formula:

o FITA (Olympic Style) 11% to 16%
o 3-D Archery 6% to 12%
o Field Archery 10% to 15%
o Hunting 10% to 15%

FITA shooters, who compete at the longest ranges, use the highest average FOC’s; 3-D shooters the lowest; with field archers and hunters in-between.

Why do FITA shooters prefer a high amount of FOC?

They are seeking precision long range accuracy. To achieve this, the arrows must be very stable in flight. High FOC permits stabilization from relative smaller fletching. Smaller fletching offers a lower drag factor and is less subject to the effects of cross-winds than larger fletching. These factors become important at the extreme ranges at which FITA shooters compete.

What is the lowest FOC usable?

Hunters need fairly high FOC. Broadheads exert a steering effect upon the arrow, due to wind-shear. Fletching must to overcome these "wind-plane" forces. High FOC means fletching has a longer "lever", and more steering control. The shorter the arrow one shoots, the higher the FOC should be. Shorter arrows are inherently less stable in flight. The longer rear lever helps fletching overcome this. A finger release also adds to arrow instability, especially ininitial flight. Here to, high FOC is beneficial.

Spine selection


Static spine measures relative stiffness of a shaft; how much it flexes when a weight of specified mass is suspended mid-way between two shaft-supporting points; which are located a specified distance apart.

Everything about the measurement is relative, not absolute. Static spine tells nothing of an arrow’s dynamic spine. From it one gleans only an indication of relative stiffness. What it does do is provide a reference point. This helps when one needs to move to a stiffer or softer spine. It allows comparison of shafts; relative to each other. This is why tuning arrow to bow is important. No static measurement or calculation contends with the myriad variables encountered when one shoots an arrow from a bow. That’s why, besides charts, Easton publishes 35 instructional pages on attaining "the right arrow". Charts provide no magic number saying; "Pick me. I’m the right one!"

Why does Extreme FOC give more tissue penetration?

They encounter lower resistance. The reduced resistance results from less shaft-flex on impact. Prior testing has shown shaft flex increases shaft-drag, and shaft-drag is a major influencing factor on penetration.


How and why do Extreme FOC arrows achieve this reduction in shaft flex?

Reduced shaft flex is related to CP location, relative to the arrow’s center of mass. Extreme FOC means the predominate arrow mass has a very short lever arm. The shorter this lever arm, the less the flexion when obliquely acting force is applied at the arrow’s tip. It is suspected that, for a given shaft, the effect may be proportional to the ratio of the lever arms; when all else is equal. Should this prove true, one would want as high a FOC as possible when maximizing penetration.

Extreme FOC arrows have at least two design features which reduce shaft flex on impact. These are:

1. Less arrow mass is towards the rear, reducing the force with which the arrow’s rear "pushes" on the shaft.

This is easier to understand if one thinks of super-gluing a brick to one end of a slender shaft. Now place the other end of the shaft on the floor. Unless one keeps the shaft absolutely perpendicular to the floor, the shaft flexes. Next, bump the shaft against the floor. Even when perpendicular, the shaft flexes at impact. Collision forces are required to go somewhere. The resultant force vector; between floor-impact and "push" from the rear; must either compress the shaft linearly, or be redirected, causing shaft flex.

Now reverse the shaft, placing the brick on the floor. The shaft does not flex. Bump it up and down. Shaft flex is scarcely visible. This is a drastic example of this Extreme FOC effect, but clearly demonstrates what happens.

2. Extreme FOC arrows concentrate arrow mass far forward.

The forward lever arm is short. This means the dynamic center of pressure at impact is also far forward. To understand how this short lever with forward mass affects shaft-flex, think of the distance from arrow front to balance point as being a short section of shaft. The shorter the section, the stiffer it is. The stiffer it is, the less it flexes.

Here one may wish to use the slender shaft and brick again. Hold the shaft near mid-point and turn it such that the shaft is not vertical. Note the "bending". Without changing the angle at which the shaft is held, shorten the "forward lever" by holding closer to the brick. The shaft flexes less. The closer one’s hand is to the brick, the less the brick’s "given force" flexes the shaft.

　

It is hoped the forgoing will help clarify FOC, how it is used, and its many effects. but as I have stated before - the older, experianced guys probably know all this stuff already - this might be interesting for the new guy's though.

[willyqbc]

couple good posts Kudu! I totally agree with the idea that high FOC has benefits upon impact and can have benefits for long range shooting. My concern with high FOC arrows for hunting is that most hunting shot ranges are closer than the other disciplines mentioned....sometimes extremely close. As such the amount of flex in an arrow as it leaves the string concerns me as the more it flexes the farther the arrow will travel before stabilizing. For myself I will take an arrow that stabilizes quicker and carries a better trajectory over one that looses some penetration due to flexing on impact. Most modern set-ups if set-up correctly will have more than enough energy for pass throughs, even with a lighter arrow. I think both sides of the argument have merit and each side has its particular downfalls....as with most things archery related I think you have to weigh the pro's and cons of a particular set-up and decide what you think is best for you! Either way I think a moose shot with your arrow or mine will probably end in the same result!

Just my opinion
Chris

[Bow Walker]

I think that arrows that have an Extreme F.O.C. are made from (and utilize) a far stiffer spine than an arrows with an F.O.C. that falls within the accepted norms of 7% - 12% for AL's and 10% - 15% for carbons. Not so? To my way of thinking they'd have to be made this way to fly correctly.

[Kudu]

couple good posts Kudu! I totally agree with the idea that high FOC has benefits upon impact and can have benefits for long range shooting. My concern with high FOC arrows for hunting is that most hunting shot ranges are closer than the other disciplines mentioned....sometimes extremely close. As such the amount of flex in an arrow as it leaves the string concerns me as the more it flexes the farther the arrow will travel before stabilizing. For myself I will take an arrow that stabilizes quicker and carries a better trajectory over one that looses some penetration due to flexing on impact. Most modern set-ups if set-up correctly will have more than enough energy for pass throughs, even with a lighter arrow. I think both sides of the argument have merit and each side has its particular downfalls....as with most things archery related I think you have to weigh the pro's and cons of a particular set-up and decide what you think is best for you! Either way I think a moose shot with your arrow or mine will probably end in the same result!

Just my opinion
Chris

Absolutely, I agree. As you say in both cases The Moose is toast.

The next time you find yourself down this way Chris - please give me a shout, I would love to get together for a beer or two.

All the best

Mike

[copeyshort]

if your looking for a arrow that wouldn't make you cry when you miss the intended target try a carbon express rebel. they are a decent arrow i know lots of guys who shoot them and are very happy with them. I shot them for about a year when i first got my bow i've since moved up to easton beman fatboys they are a great arrow for 3-D shoots and hunting but they get pricey if you miss. I would for sure look into carbon express rebels if i was you.