Deer Creek Archery's
When building hunting and target arrows, we have already covered the idea of total arrow weight, and how it can affect momentum and kinetic energy. However, before your arrow gets to your target or the animal, it needs to fly straight, and that is where this week's topic FOC (front of center) comes into play.
FOC is the term used to describe the balance point of your arrow not being at the true middle of the arrow, but rather slightly forward of the center (hence the name). Ideally, this number should be about 10-20% of the total arrow length. So, as an example, if an arrow's total length is 30", the FOC point should be approximately 3-6" in front of the exact center of the arrow. The reason it is desirable to have the FOC so high is because the arrow will fly truer. With the weight distributed that way, the arrow's fletchings conduct the air around the arrow to guide it more effectively, and the arrow doesn't get thrown off course. Below is a schematic of how the balance point of the arrow should be aligned.
If your FOC is correct, your arrows will fly straighter, and conduct the air around the arrow more effeciently. However, if your arrow's FOC is off, the fletchings of the arrow will produce too much drag and send the point of your arrow in different directions, and the arrow flight will be very erratic, resulting in poor shot placement on the animal you're hunting, or a missed shot on a target. But don't go overboard on the FOC- if the weight is too far forward, the arrow will sink into the dirt at even short distances.
To test the FOC of your arrow, balance the arrow on your finger (or any object) so that you can see where the arrow balances. You then find the center of your arrow by measuring the total arrow length from the end of the shaft to the throat of the nock, and then mark the center of the arrow. From there, mark the arrow and measure the distance from the center of the arrow to that mark. Calculate the percentage of the total arrow length that the FOC distance makes up, and make sure that number is between 10-20%!
See below to see an example of an arrow that has poor FOC and an arrow that has solid FOC.
When you are building your hunting arrows, you need to ensure that your FOC is well designed, otherwise your arrows will fly in unexpected and inaccurate ways, causing poor shot placement, slower and less ethical kills, and unpredictable results. The target archers need to know that this simple arrow set up principle can cost them the match!
Stop in to Deer Creek Archery soon and we will help you figure out your arrows' FOC, and help you reconstruct or setup your arrow builds for a more ideal shot!
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