Teach me FOC
03-11-2008, 12:14 PM
#62
Join Date: Feb 2003
Location: Howard PA USA
Posts: 2,221
RE: Teach me FOC
ORIGINAL: Ausie-guy
Jeff.
Pm me your phone number and I will give you a call tonight and answer any of your questions and hopefully put you on the right track
Jeff.
Pm me your phone number and I will give you a call tonight and answer any of your questions and hopefully put you on the right track
03-11-2008, 12:14 PM
#63
Join Date: Jan 2004
Location: Eureka, MO
Posts: 3,703
RE: Teach me FOC
FOC is all about stable flight. But you have to consider that the arrow's flight is not done until it comes to a complete stop. In other words, it is still in flight during the time it's penetrating that animal.
High FOC allows the arrow to remain more stable and resist deflection when it contacts ribs and such while passing through. A low FOC arrow can deflect off a rib, causing the shaft to have more contact with the surrounding tissues, causing extra drag and reducing the arrow's penetration. If the arrow can keep it's KE and momentum going in a straighter line - more stable flight path - while penetrating, it'll penetrate deeper.
That's my theory and I'm stickin' to it.
_____________________________
High FOC allows the arrow to remain more stable and resist deflection when it contacts ribs and such while passing through. A low FOC arrow can deflect off a rib, causing the shaft to have more contact with the surrounding tissues, causing extra drag and reducing the arrow's penetration. If the arrow can keep it's KE and momentum going in a straighter line - more stable flight path - while penetrating, it'll penetrate deeper.
That's my theory and I'm stickin' to it.
_____________________________
I'm sticking to it too.
03-11-2008, 12:18 PM
#64
Nontypical Buck
Join Date: Jun 2006
Location: Southeast, VA
Posts: 2,119
RE: Teach me FOC
Jeff,
This might be kind of lazy but when I googled FOC, Arrow flight/penetration, Dr. Ed Ashby anything along those lines. There is a mountain of info and charts and graphs and arrow building calculators and comparisons between compounds / tradition set-ups and even links to hunting.net past threads about the topic. You coulf probably read forfew days on the topic. Some really good stuff on ke and penetration I just read by Ashby.
This might be kind of lazy but when I googled FOC, Arrow flight/penetration, Dr. Ed Ashby anything along those lines. There is a mountain of info and charts and graphs and arrow building calculators and comparisons between compounds / tradition set-ups and even links to hunting.net past threads about the topic. You coulf probably read forfew days on the topic. Some really good stuff on ke and penetration I just read by Ashby.
03-11-2008, 12:24 PM
#65
Boone & Crockett
Join Date: Oct 1998
Location: Hughesville, PA USA
Posts: 18,322
RE: Teach me FOC
Not to mention if the back end of the arrow is equal or heavier than the front end of the arrow it takes more fletch, "drag" to stabilize the arrow resulting in tailing etc...think of it this way, if the back end was heavier and there wasn't adequate stabilization, the back end would want to become the front end. It never happens but out of a poorly tuned bow, it could. A low FOC only compounds tuning issues.
03-11-2008, 12:32 PM
#66
Join Date: Mar 2005
Location: Colorado
Posts: 4,127
RE: Teach me FOC
I can visualize an arrow, either when it is under load from the bowstring, or when the tip encounters resistance; wanting to bend under force. In the case of the arrow's tip entering an animal, the back of the arrow will want to try to overtake the tip if the weight is distributed more to the rear. So the arrow will bend or yaw and cause a loss of penetration. Having more of the arrow's weight distributed towards the front of arrow will cause it to be more prone to pushing straight through the animal. Makes sense to me.
03-11-2008, 04:02 PM
#67
Nontypical Buck
Join Date: Feb 2007
Location: Milwaukee WI
Posts: 1,161
RE: Teach me FOC
I've read and studied zero articles about FOC and how it affects penetration but I've got a decent sense of physics I think, and here's what I think Jeff:
I'm sure other guys have already said this (I didn't read all the posts) but maybe if put in a different way, it'll all of a sudden click... Your arrow in abest case scenario enters the animal perfectly square (straight). As soon as it hits anything with a consistency less than air, it'll want to deviate from that straight line. The more weight that you have towards the rear of the arrow, the greater the tendency to deviate from that straight line because there's more weight back there to steer the front of the arrow.When there's deviation, some of the KE in that arrow is spent by the shaft (not the tip) pushing against the walls of the hole that the arrow is creating. Resulting in more side to side push ratherthan forward push. Resulting in less penetration.
Another way to think about it is throwing a baseball bat into water like a spear. If you throw it handle end first you have low, in this case, negative FOC. It probably wont govery deep into the water before doing a flip. On the other hand, if you throw the baseball bat heavy end first, it'll penetrate through the water much better and probably wont do a flip at all.
I'm sure other guys have already said this (I didn't read all the posts) but maybe if put in a different way, it'll all of a sudden click... Your arrow in abest case scenario enters the animal perfectly square (straight). As soon as it hits anything with a consistency less than air, it'll want to deviate from that straight line. The more weight that you have towards the rear of the arrow, the greater the tendency to deviate from that straight line because there's more weight back there to steer the front of the arrow.When there's deviation, some of the KE in that arrow is spent by the shaft (not the tip) pushing against the walls of the hole that the arrow is creating. Resulting in more side to side push ratherthan forward push. Resulting in less penetration.
Another way to think about it is throwing a baseball bat into water like a spear. If you throw it handle end first you have low, in this case, negative FOC. It probably wont govery deep into the water before doing a flip. On the other hand, if you throw the baseball bat heavy end first, it'll penetrate through the water much better and probably wont do a flip at all.
03-11-2008, 05:10 PM
#69
Giant Nontypical
Join Date: Feb 2003
Location: HENDERSON KY USA
Posts: 6,634
RE: Teach me FOC
When shooting higher ke,you can shoot lower foc and still get good arrow flight,but if you are shooting on the low end of ke,you better pay attention to it.I always had best result when shooting 10% or higher for open class 3-d.
03-11-2008, 05:14 PM
#70
Nontypical Buck
Join Date: Feb 2007
Location: SE Ohio
Posts: 2,531
RE: Teach me FOC
ORIGINAL: Hoytail Hunter
I've read and studied zero articles about FOC and how it affects penetration but I've got a decent sense of physics I think, and here's what I think Jeff:
I'm sure other guys have already said this (I didn't read all the posts) but maybe if put in a different way, it'll all of a sudden click... Your arrow in abest case scenario enters the animal perfectly square (straight). As soon as it hits anything with a consistency less than air, it'll want to deviate from that straight line. The more weight that you have towards the rear of the arrow, the greater the tendency to deviate from that straight line because there's more weight back there to steer the front of the arrow.When there's deviation, some of the KE in that arrow is spent by the shaft (not the tip) pushing against the walls of the hole that the arrow is creating. Resulting in more side to side push ratherthan forward push. Resulting in less penetration.
Another way to think about it is throwing a baseball bat into water like a spear. If you throw it handle end first you have low, in this case, negative FOC. It probably wont govery deep into the water before doing a flip. On the other hand, if you throw the baseball bat heavy end first, it'll penetrate through the water much better and probably wont do a flip at all.
I've read and studied zero articles about FOC and how it affects penetration but I've got a decent sense of physics I think, and here's what I think Jeff:
I'm sure other guys have already said this (I didn't read all the posts) but maybe if put in a different way, it'll all of a sudden click... Your arrow in abest case scenario enters the animal perfectly square (straight). As soon as it hits anything with a consistency less than air, it'll want to deviate from that straight line. The more weight that you have towards the rear of the arrow, the greater the tendency to deviate from that straight line because there's more weight back there to steer the front of the arrow.When there's deviation, some of the KE in that arrow is spent by the shaft (not the tip) pushing against the walls of the hole that the arrow is creating. Resulting in more side to side push ratherthan forward push. Resulting in less penetration.
Another way to think about it is throwing a baseball bat into water like a spear. If you throw it handle end first you have low, in this case, negative FOC. It probably wont govery deep into the water before doing a flip. On the other hand, if you throw the baseball bat heavy end first, it'll penetrate through the water much better and probably wont do a flip at all.