Trad Gang

Main Boards => PowWow => Topic started by: Dr. Ed Ashby on January 24, 2008, 10:18:00 AM

Title: It's FOC ... with
Post by: Dr. Ed Ashby on January 24, 2008, 10:18:00 AM
Haven't had a chance to check TG in a while. I see several threads on how to achieve Extreme FOC posted, and have quickly scanned them. One thing I'm seeing is a lot of really good ideas about possible ways to get higher amounts of FOC, especially on woods.

One word of caution. Achieveing the maximum benefits from increasing the FOC of you arrows REQUIRES that your arrow have PERFECT FLIGHT along with the higher FOC. This means you need to work for BOTH the higher FOC and perfect bare shaft flight.

Just though I'd mention that, because I'm not seeing much discussion on quality of flight on those threads. I routinely note that the flight of many folks' arrows, which they self-describe as "perfect", are what I would call very marginal.

Don't expect to achieve all the great penetration benefits possible with Extreme FOC unless you also get those arrows flying as perfectly as you can! When developing your Extreme FOC arrows, you'll need to pay great attention to both.

Ed
Title: Re: It's FOC ... with
Post by: SlowBowinMO on January 24, 2008, 10:26:00 AM
Great point!  It's easy to get off on a bunny trail with some new adventure and forget the basics.
Title: Re: It's FOC ... with
Post by: Guru on January 24, 2008, 10:56:00 AM
Very well said Doc    :thumbsup:
Title: Re: It's FOC ... with
Post by: T Folts on January 24, 2008, 11:28:00 AM
Thanks Doc, I am at the begining stages of setting up carbons so both arrow flight and FOC are equal in value to me, cant have one without the other.
Thanks for all you do!
Terry
Title: Re: It's FOC ... with
Post by: tiur on January 24, 2008, 11:31:00 AM
Dr. ed,
did you have chance to visit OL, i sendt him
some custom 300gr Broadheads, they are on B.Morrison
site - see new heads,can we send you some??
Title: Re: It's FOC ... with
Post by: RamiusEng on January 24, 2008, 11:59:00 AM
Dr. Ashby,

Moving forward the F.O.C. increases the flight quality.  It is a win-win situation.  As the distance between the center of pressure (CP) and center of gravity(CG) increases the arrow can right itself easier.  There is a moment arm between the CP and the CG.  The farther back the CP, from the CG, the more arrow will want to fly true because it makes the fletching much more effective.  This is why I love your Extreme FOC theory.  It fits and physically it should beautifully.

Just my $0.02
Title: Re: It's FOC ... with
Post by: Dirty Bill on January 24, 2008, 12:27:00 PM
I just achieved 15% foc last week.I had to move my nocking point.At the same time I turned th cock feather in.I used to do that years ago,after talking to Jack Howard.

With the arrows set up like this,I am getting very good flight,as far as I can tell. On a warm day when I can shoot @ 30 yards,I will know for sure.

So far I like it,and I am going to try for 20% foc.
Title: Re: It's FOC ... with
Post by: Jason R. Wesbrock on January 24, 2008, 01:37:00 PM
QuoteOriginally posted by Dr. Ed Ashby:
One word of caution. Achieveing the maximum benefits from increasing the FOC of you arrows REQUIRES that your arrow have PERFECT FLIGHT along with the higher FOC. This means you need to work for BOTH the higher FOC and perfect bare shaft flight.

Just though I'd mention that, because I'm not seeing much discussion on quality of flight on those threads. I routinely note that the flight of many folks' arrows, which they self-describe as "perfect", are what I would call very marginal.

Don't expect to achieve all the great penetration benefits possible with Extreme FOC unless you also get those arrows flying as perfectly as you can! When developing your Extreme FOC arrows, you'll need to pay great attention to both.

Ed
Excellent advice!

I find it odd that point #2 (before you even got into FOC, bevels and whatnot) in the last TBM article concerns quality of arrow flight. And yet I don't think I've seen a single thread here or anywhere else that starts off along the lines of, "I just read the latest Ashby article and I want to learn more about bow tuning".

Honestly, I've long held that the single largest hindrance to good penetration on game animals is poor bow tuning. Last year I met a very nice gentleman at one of the larger traditional shoots who had a mid-60's poundage ACS longbow. He said he liked it, but even with heavy arrows he failed to get pass throughs on two whitetail does, even with 2-blade COI heads.

I found that strange because the previous September I'd shot completely through a bull moose with arrows a lot lighter than his, and a bow putting out far less energy that what he was using.  

After watching his arrow fly, the problem was obvious. His arrows looked like finely-crafted corkscrew sailing through the air.
Title: Re: It's FOC ... with
Post by: leatherneck on January 24, 2008, 07:21:00 PM
I have recently moved to 21% front of center and am having good arrow flight with bare shafts to broadheads. Don't be scared Bill, take the plunge! When my elbow heals up me and Ben are conming over to shoot with you. It's been a very long time since we've met but enjoyed your hospitality.

Mike
Title: Re: It's FOC ... with
Post by: Dirty Bill on January 24, 2008, 07:32:00 PM
Hey Mike,we can do that. I pretty much know how to tune the bow/arrow..lol. I just need some good heavy broadheads,around 190 grains that glue on.I might be able to do it with 160 grains also. I'll be experimenting.   :campfire:
Title: Re: It's FOC ... with
Post by: imbowhunt10 on January 27, 2008, 01:02:00 PM
I'm kind of confused on how to figure my FoC. My shaft lenth is 27 1/4, my center of balance is 19 3/4. According to DR. Asbey I then divide the two which gives me 1.38. I then subtract o.50 which gives me .88. Then mulitply by 100 or move the decimal point two places to the right which gives me 88. Is this mean 88% or am I not doing it right. I followed his directions in his article in Tradition Bowhunter Feb/March issue. Thanks
Title: Re: It's FOC ... with
Post by: Billy on January 27, 2008, 01:54:00 PM
More to Dr. Ed's point; I thought I had 'good' arrow flight...
yesterday, i was shooting my full length
GT 35-55, 100 grain brass, 125 points with @ 18% FOC and shooting decent.
I showed Brent (bgremill) one of my arrows that had hit a concrete curb and split the front 3/4" out. He took it in to the saw , cut off an inch, reglued the insert...we shot some more,got us to thinking; so we cut one more an inch shorter.
The full lengths were grouping slightly right and spread out. The 29's were closer to center and stacking.
Now that I've seen the difference between good and better, I'll be working toward BEST flight.
Thanks Doc, for a timely reminder.
Title: Re: It's FOC ... with
Post by: BernieH on January 27, 2008, 03:24:00 PM
imbowhunt10 your FOC should work out to 22.5%.
((19.75/27.25)-.5)*100=22.5%