What is your % front of center

[archer66]

Hello all....sorry if this has been discussed again and again.  I did a quick search but didn't find exactly the same discussion but if it exists feel free to direct me there.

I got a new bow and I'm working up some arrow options using Stu Millers Dynamic Spine Calculator.  I know it's not substitute for testing arrows with my actual bow but I thought it would give me a couple of good starting points.  Anyway...I'm coming up with some pretty high front of center calculations (18-20) and I seem to remember that a setup is most efficient if you stay in the 7-15 percent range.  

I'm interested to hear your input on that thought and to hear what your thoughts are on going higher?  Also...what is your front of center on some of your favorite hunting rigs.

Thanks in advance!!!

[Mike Vines]

Click on and read every tab on the left side of this page...

  http://www.tuffhead.com/

That's a lot of homework, Mike!        

High FOC is a good thing!

My arrows are just over 22% FOC at 10.3gpp.

Bisch

[McDave]

FOC is somewhat of a moving target, because there is no universal agreement on what part of the arrow to measure, etc.  18-20% is fine, IF the arrow flies true, based on bare shaft tuning or whatever other method you use.  Actually, Olympic archers favor a high FOC because it stabilizes arrows at longer ranges.  The lower FOC is favored by those who want to reduce overall arrow weight and maintain a flat shooting arrow at shorter than Olympic distances, like for typical trad bow 3D shoots. For hunting, if you want a heavy head for max penetration, you're looking at more FOC.

[katman]

http://tradgang.com/noncgi/ultimatebb.php?ubb=forum;f=24

LOTS of information here, especially on foc.

If setting up a new arrow I see nothing wrong with choosing components to maximize your foc at the total weight you want. Is it needed for deer? nope, lots of critters killed with the lower foc you listed. But I find the higher foc very stable in flight, comes out of paradox quicker and flexes less on impact due to the stiffer static spine shaft which should yield better penetration.

To answer your original question I am running 25% at 11gpp.

[archer66]

Thanks for the homework Mike Vines!!  I've seen Dr. Ashby's reports before and should have gone straight to them!!  

Thanks also to Katman for the links.

[**DONOTDELETE**]

Anything in the 10-20% will fly great for you and get her done, But i wouldn't recommend going below 10%.

There are lots of guys that prefer the EFOC arrow set ups which is 19% or more.There is a lot to be said about using a stiffer spine with more up front weight.

I'm running about 19% on my current set up. with a total of 235 up front with 50 grains of brass and 185 grain Grizzly single bevels.

[jmar595]

If you have a high FOC does that tend to make the tip drop quickly? I am experimenting now with this and see that the arrows drop the nose quickly when I had a lot of weight up front.

[Sapcut]

Wonder who came up with the most efficient FOC being 7-15%.  Can't imagine what they're thinking. No FOC is worth a flip if the arrow is not tuned flying right.... but of course everyone already knows that.

My arrows are 31-33% FOC and never do I plan to build an arrow with less.  High FOC arrows are much easier to tune with a wide range of spine allowing for a wide range in point weight....and still stay tuned.  High FOC arrows also seem to fly much more stable and more consistent than an arrow with low FOC.

[archer66]

Originally posted by Sapcut:
Wonder who came up with the most efficient FOC being 7-15%.  Can't imagine what they're thinking. No FOC is worth a flip if the arrow is not tuned flying right.... but of course everyone already knows that.

My arrows are 31-33% FOC and never do I plan to build an arrow with less.  High FOC arrows are much easier to tune with a wide range of spine allowing for a wide range in point weight....and still stay tuned.  High FOC arrows also seem to fly much more stable and more consistent than an arrow with low FOC.

I actually got that from Gold Tip's website.....it's possible I misunderstood their intent.....  --->http://www.goldtip.com/calculatorcontent.aspx?coid=2

Here's a paste from their website:

A projectile's flight is most stable when most of the projectile's mass is positioned Front of Center (F.O.C.). As such, an arrow should be heavier in the front than in the back. But how much? Where's the "perfect" balance point?

 

This is another hotly debated issue among archery enthusiasts. Some claim that F.O.C. makes little or no difference, others swear that F.O.C. has a profound effect on accuracy. Even the industry experts don't seem to agree, as the ballistic physics for F.O.C. include some rather elastic variables that make finding an "mathematically optimal" F.O.C. very difficult to declare and prove. To make matters worse, we even see a variation in how F.O.C. itself is calculated, depending upon which "expert" you ask. So while we have no interest in the fine points of the debate, we will agree that the tricky issue of F.O.C. is at least worth considering when purchasing a new set of arrows.

 

With all that said, it is generally believed that an arrow with a high F.O.C. will fly well, but with premature loss of trajectory (nose-diving). While an arrow with a low F.O.C. will hold it's trajectory better, but it will fly erratically. So again, another trade-off for you to consider.

 

So what should you be looking for?

 

It is generally agreed that the optimal F.O.C.% balance for an arrow is somewhere between 7% and 15%. In the example on the above, the 30" long arrow has balance point that is 3" forward of the arrow's actual center (15"). So it's F.O.C. is 3/30 or 10% - a reasonable F.O.C. balance.

[katman]

Originally posted by jmar595:
If you have a high FOC does that tend to make the tip drop quickly? I am experimenting now with this and see that the arrows drop the nose quickly when I had a lot of weight up front.

High foc does NOT make the tip drop quickly. The extra weight of the entire arrow will slow it down so the entire arrow has more time to drop. Choosing the right shaft, lighter gpi, will keep total arrow weight within reason. I would check your nock point height if you see nose diving.

[damascusdave]

I am shooting some arrows that weigh over 900 grains right now...I recently shot them at a 3D shoot and did about the same as I usually do...not great but not badly either considering that most of my shooting lately has been at about 12 to 15 feet in my basement..as much by luck as good management they are around 15% FOC...the key to shooting heavy arrows like that is an efficient bow and string combination...I have Chronied those arrows at 155 fps out of two of my bows...I understand that I really do not need arrows that heavy, but as long as I can hit with them at reasonable distances they will be my elk arrows...an elk kill zone is a pretty big target

DDave

[BigJim]

I stopped figuring that % when I realized it was contaminating my brain.
I now look at what I want in total grain weight...personally I shoot for 10 gpp +- and with carbon arrows, that will always mean efoc unless you are shooting an arrow that is too stiff.
I then bare shaft until I feel good about the tune and follow up with fletched field tip and broad head arrows.
If your arrows are tuned well, they will fly straight and your broad heads and field tips will both go to the same place you are looking.
Once I achieve this I quit thinking about my arrows and set up.
The key to good shooting is confidence...all the other things are no good without it. When my set up is tuned I have the confidence I need to forget about everything else except making the shot.
BigJIm

[archer66]

Thanks all....it was good to go back and re-read the Ashby reports....really good stuff in there.

Big Jim....I agree completely about confidence.....that to me is the biggest hurdle to overcome in traditional archery.