driftrider

I know that FOC is important, but I trust bowjacksons FOC calculator to only give me a ballpark estimate, but it can't account for slight variations in each individual arrow.

So my questions are as follows:

1.) Will a slight variation in arrow FOC, provided they are within the acceptable range, cause any serious accuracy problems?

2.) Are there any arrow balancers that allow one to accurately and easily(without it constantly rolling around) measure the balance point of each arrow?

I just tend to follow the old saying, &quot;Close is only good enough in horseshoes and hand grenades!&quot;<img src=icon_smile_big.gif border=0 align=middle>

Thanks,
Mike



Gun control means putting the second bullet through the same hole as the first- Ted Nugent

FLHunter

Mike,

No there should be no accuracy problems with slight variations in FOC. In fact I have shot fixed broadheads down around 8% and target arrows in the 6% range without any problems. There is a wider range than most archers think shooting a compound with a release and shoot through rest. Besides a calulated FOC there is an effective FOC to most arrows. This is due to the increased drag on the aft of the arrow as the velocity increases giving the arrow more dynamic FOC. A lot of it also has to do with the arrow being correctly spined, your bow being tuned well, good shooting form and you can widen the parameters a bit. If you take your time you can take the measurements on your arrow and do the raw computations for yourself. Its really not that hard to get the balance or FOC point. Personally I think Steve Jackson's calculator is adequate enough.

Edited by - FLHunter on 01/04/2002 15:45:40

55#recurve

Im just wondering about windfactors and superlight arrows, there has got to be some affect with low FOC I would think. I try to stay up around 12% for my ACE's so the wind doesnt make them run 10 yards sideways at 90-70metres, even at 30 with high wind the arrow drag can be vicious. Just a few questions. Good shooting.
Dylan

>>>>--------o-->

FLHunter

Dylan,

An arrow drifts in the air mass at the rate that the wind is moving. To see this think about an airplane that is flying on a course South to North for an hours time with a 90 degree crosswind of 20 mph hour from the West. If the pilot makes no attempt to correct for the wind the aircraft will be 20 miles off course to the East in that hours time and the aircrafts heading is still due north. FOC has nothing to do with air mass movement. The amount of drift on your arrow depends on the strength and the direction of the crosswind relative to the target, plus the amount of time that your arrow is airborne. The more time the arrow is airborne the greater the distance the arrow moves in the mass before it lands. Hope this helps.

CargoF16

So what FOC do you look for in your 3D arrows versus your hunting arrows? What flight characteristics would an arrow with a low FOC have over an arrow with a High FOC? Thanks in advance for educating me.

Rick

FLHunter

Rick,

I see that you are back in country again! As far as FOC there are many opinions on it, but it is not as critical as some think. I like to stay about 10-12% on all of my arrows, but will shoot lighter if I am trying to achieve a lighter arrow. As I mentioned above there is an &quot;effective FOC&quot; which is higher than the computed, this is generated by the parasite drag. As the speed of the arrow is increased the drag increases drastically. Depending on the type of fletching you are shooting the drag will vary, with feathers it probably quadruples for a given increase in speed, giving you added stabilization. From flying you know if your CG is too far forward the aircraft nose is hard to lift, with an arrow it causes the arrow to want to drop out quicker with extra nose down flight characteristics (extra drag). If you have a light FOC, with a properly spined arrow and a tuned bow you will see very little ill effect with fieldpoints. Shooting fixed broadheads is another story with the canard the blades provide on the front of the arrow creating some lift. If the FOC(CG) is too light it may cause the arrow to tip stall which maybe seen as porposing. As I stated I have been as light as 8% on my broadheads and they grouped right with my fieldpoints. So if your arrows are grouping well and it ain't broke, don't worry about it. If you have an old arrow without a tip shoot it 60-80 yds, you will find that it flies pretty well in most cases. This is because of the stabilization of the fletching which increases the effective FOC. Steve Jackson can give you more on effective FOC, but what I gave you is the long and short of it the way I understand it.

Some of the trad. shooters will use very high FOC's which tends to drive the arrow, but they tend not to shoot out very far, 20-25yds in most of their shooting. A traditional field archer will generally have their FOC close to the 10-12% range in most cases to maintain arrow flight. Reaching out to 60-80 yards for them is sometimes a problem depending on the bow.

For 3-D a FOC anywhere from 8-12% would be plenty fine, but as I said I have shot at 6% before and it worked out fine.

Edited by - FLHunter on 01/05/2002 10:51:17

Edited by - FLHunter on 01/05/2002 10:53:03

sajackson

FLHunter and I disagree on some aspects of the FOC topic, I contend and many FITA shooters would contend(I believe McKinney has documented it) that a low FOC hurts performance in wind at those 70 and 90 meter distances especially on light arrows. From the side FOC helps the arrow act like a weathervane and steer somewhat back into the wind or at least keep better on track.

Higher FOC also lowers the drag of the arrow, this may seem backwards at first, however the FOC helps keep the arrow shaft movement in line with the path of the arrow, by keeping the nose pointing in th edirection of gravity. Due to gravity, all arrows will follow a parabolic curve after launch, a low FOC will tend to be more nose-up(at extreme ends of the normal range), this causes the arrow shaft to be traveling at an angle to the arrow path(using it somewhat as a lifting body). Flight arrows use this effect to get more distance, typically very low FOC even zero the way we normally calculate it, but penetration if required would certainly suffer.

FLHunter

Steve,

Since you disagree with some aspects please expand on what the allowable ranges of FOC should be. I do remember you addressing effective FOC generated by drag coefficents. Maybe I miss interputed what you had to say previously, but I have had no negative effects down to the 6-8% range for the most part. I do understand that too light is a big problem, and that a relatively heavy FOC drives the arrow, very similiar to a rock on a string. Where are the acceptable ranges from your prespective for field, 3-D, and hunting? Please address from the trad. and compound sides of the house. Thanks!!!

sajackson

I think we're all really talking the same ranges of FOC. Easton's recommendations generally keep you pretty safe.

When I was discussing the drag connection, I think it was in relation to shooting a fast setup where you can get away with lower FOC than for a slow setup, by virtue of the fletches exerting more influence due to drag(increases as the square of velocity). But that was in a 3D context. With broadheads, the effects at the front are affected by velocity equally at the back. You can certainly get broadheads to fly at lower than recommended FOC, but performance over a given range of conditions may not be equal as a higher FOC arrow of the same build.

As far as nose-diving, this effect of FOC is hardly noticeable over the Easton recommended ranges of FOC, even out to 90-100 yards, that I've been able to tell(it may be more noticeable with straight fletch, no offset or helical though due to the lack of torque moment thru the arow shaft).

55#recurve

Steve, I was thinking about trying to shoot some CXL for outdoors, they are a new carbon by Gametracker, I talked to the national sales manager, I can't remember his name off hand, but he said that they have had great results with testing. Here is the deal, they are under the 23 thous. for the rules of Fita and NFAA. I think there actual diameter is 9.1mm, they have a monster diameter compared to my ACE. If I was to shoot them out of my recurve at 44-45# do think they would fly rotten out at 90-70metres or all of the distances for that matter. The reason I am asking this is because of the horrid price of ACE and I think that Mr Polzin could get me a sponsorship perhaps, If I shoot and do well with gametrackers arrows. Could you give me some insight please on all I have asked.
Thanks
Dylan

>>>>--------o-->