[glynT]

I would like to say I prefer a discussion vs arguments. granted the title of the post gets attention.

1. archers paradox - the bending of an arrow around the recurve bow. basically.. I believe that's where FOC started. pretty sure I am wrong.
2. compound bow - I feel that archers paradox does NOT apply to a compound because the arrow does NOT bend around the bow.
3. arrow spine - yes, FOC does come into play when recovery of an arrow after released. a stiff spine will always fly better than a weak spine.

here is my dilemma. first take out the whole bow flex, torque and you have a completely tuned bow and steady hand.

you are shooting a compound bow. you have 2 connecting points to the arrow, between your arrow rest and the string. when you release, you are pushing an arrow through a guiding surface (arrow rest). in theory, it's like firing a bullet through the barrel. the longer the barrel, the more accurate a bullet is. in theory, the longer an arrow stays on the rest, the more accurate the arrow due to it being guided.

now, the higher the FOC the more flex which in turn the arrow is fighting the wind to become stable. that turns into less speed and KE.

the lower FOC or completely balanced arrow with a very stiff spine becomes a "bullet". your arrow basically recovers right off the rest, the vanes can do their job and you have a faster arrow and more KE on impact.

take for instance a cross bow, the arrow travels down the rails and leaves the bow, that arrow doesn't flex like a lot of hunters that have to have 15+ FOC.


so if you want your arrow to recover faster, be more accurate, have more KE, always choose the stiffer spine and center balance your arrow.

saying all of this I do shoot a 2% FOC. my arrow setup is black eagle X-impact with their outcerts on both ends (yes, both ends). 100gr grim reaper on one end and NuFletch on the other. arrows weigh in a 560 grains +/- a few. bow is APA archery king cobra TF with 80 lb limbs. arrows hit like bricks!! sighted in from 20 yards to 80 yards.


now, lets discuss (NOT ARGUE). can anyone clear up anything I have stated incorrectly?

 

[whiz-Oz]

You're wrong on a few points. I will tackle them in sequence.
Let's start with Archer's Paradox.

It has nothing to do with the arrow bending.


Archers paradox is what you see when you look at a target at full draw, with a bow without a centershot cut out. To hit the target, the arrow points off to the side.
THAT and only that is archers paradox.
It looks like this:



The term toxophilist's paradox can be found for the first time in the Feb 8th 1913 edition of Field and Stream.
It's on page 177 and the first few paragraphs look just like this.



The first time that someone actually publishes anything which incorrectly calls archers paradox the arrow bending is in Kooi's work.

If you look through his published article, you can quickly see where he decides to get it wrong. For the first 68 years of the term being published, people knew what it was.
Then Kooi came along in 1981 and published an article that gets it wrong. Thus people have been getting it wrong ever since.
http://www.bio.vu.nl/thb/users/kooi/kosp97.pdf

This is a discussion with references. It is called presenting actual proof. I've just shown anyone capable of reading the image above what was being said 105 years ago.

2. Compound bows and arrow flex.

With a release aid and a compound bow, arrows largely flex in the horizontal plane. This is why a huge range of spine values will shoot just fine out of a compound, compared to a finger released recurve.

This is a demonstrated fact that most archers just can't comprehend. Some fail to do it even when it's done right in front of them with a shooting machine as demonstrated by Dr James Park in Victoria, Australia over a decade ago.
Don't know who James Park is? Go google James Park Archery. Then spend the next hour reading about his published scientific articles dealing with arrow flight in wind tunnels and other contributions to actual archery science.

As for the arrow staying on the rest. I've got plenty of high speed footage of 1000 frames per second showing that it doesn't just sit there and be guided. There is lots of high speed footage on youtube showing the same thing.

Here's a nice one that shows perfectly what I'm talking about. He gets awesome rest clearance too, which isn't that common.

https://www.youtube.com/watch?v=CkUyYmSrRk0

Your theory about bullet length and barrels is also wrong. Accuracy is predictability and NOTHING ELSE. Predictability is consistency and NOTHING ELSE.
If you can get perfect consistency of velocity, atmospheric conditions and bullet characteristics, you will get perfect predictability. That has nothing to do with barrel length.

FOC has absolutely no directly relation to arrow flex. It is an indication of dynamic stability, or how fast an arrow will align itself to the airflow. That's it.
The higher the FOC, the MORE stabilising area and greater leverage is able to act to align the arrow to the direction of flight. It's faster.

Clarence Hickman (google him) has already done the variable CG arrow tests. The arrows with the most forward CG (highest FOC) flew the furthest.

This was done with an arrow with a moveable internal weight, so the weigh of the arrow and stiffness didn't change. Just the FOC. There is no available link online to this research, but you should have a read of Clarence N. Hickman : the father of scientific archery by Maryanne M Schumm.
https://www.amazon.com/Clarence-N-Hickman-Scientific-Archery/dp/0961358203

All the information you seek is out there so that you can understand what is going on. Most people never look.

 

[glynT]

man.... I GREATLY APPRECIATE the detailed response!! seems everyone has a theory but no real answer. I knew the answer was out there, I just didn't know where to look. I will defiantly research what you have listed.

 

[brettbrett]

science is cool!

 

[kurtzgreg1561]

You're wrong on a few points. I will tackle them in sequence.
Let's start with Archer's Paradox.

It has nothing to do with the arrow bending.


Archers paradox is what you see when you look at a target at full draw, with a bow without a centershot cut out. To hit the target, the arrow points off to the side.
THAT and only that is archers paradox.
It looks like this:

View attachment 6368177

The term toxophilist's paradox can be found for the first time in the Feb 8th 1913 edition of Field and Stream.
It's on page 177 and the first few paragraphs look just like this.

View attachment 6368179

The first time that someone actually publishes anything which incorrectly calls archers paradox the arrow bending is in Kooi's work.

If you look through his published article, you can quickly see where he decides to get it wrong. For the first 68 years of the term being published, people knew what it was.
Then Kooi came along in 1981 and published an article that gets it wrong. Thus people have been getting it wrong ever since.
http://www.bio.vu.nl/thb/users/kooi/kosp97.pdf

This is a discussion with references. It is called presenting actual proof. I've just shown anyone capable of reading the image above what was being said 105 years ago.

2. Compound bows and arrow flex.

With a release aid and a compound bow, arrows largely flex in the horizontal plane. This is why a huge range of spine values will shoot just fine out of a compound, compared to a finger released recurve.

This is a demonstrated fact that most archers just can't comprehend. Some fail to do it even when it's done right in front of them with a shooting machine as demonstrated by Dr James Park in Victoria, Australia over a decade ago.
Don't know who James Park is? Go google James Park Archery. Then spend the next hour reading about his published scientific articles dealing with arrow flight in wind tunnels and other contributions to actual archery science.

As for the arrow staying on the rest. I've got plenty of high speed footage of 1000 frames per second showing that it doesn't just sit there and be guided. There is lots of high speed footage on youtube showing the same thing.

Here's a nice one that shows perfectly what I'm talking about. He gets awesome rest clearance too, which isn't that common.

https://www.youtube.com/watch?v=CkUyYmSrRk0

Your theory about bullet length and barrels is also wrong. Accuracy is predictability and NOTHING ELSE. Predictability is consistency and NOTHING ELSE.
If you can get perfect consistency of velocity, atmospheric conditions and bullet characteristics, you will get perfect predictability. That has nothing to do with barrel length.

FOC has absolutely no directly relation to arrow flex. It is an indication of dynamic stability, or how fast an arrow will align itself to the airflow. That's it.
The higher the FOC, the MORE stabilising area and greater leverage is able to act to align the arrow to the direction of flight. It's faster.

Clarence Hickman (google him) has already done the variable CG arrow tests. The arrows with the most forward CG (highest FOC) flew the furthest.

This was done with an arrow with a moveable internal weight, so the weigh of the arrow and stiffness didn't change. Just the FOC. There is no available link online to this research, but you should have a read of Clarence N. Hickman : the father of scientific archery by Maryanne M Schumm.
https://www.amazon.com/Clarence-N-Hickman-Scientific-Archery/dp/0961358203

All the information you seek is out there so that you can understand what is going on. Most people never look.

Great rebutal. Every point you made was spot on. FOC is important and I've found higher foc arrows easier to tune and more accurate especially at longer distances. Having a 2% foc will not make your arrows fly truer or have more ke. Momentum is the true mark of penetration. Our aim should be both an entrance and an exit hole on game so penetration is paramount in hunting situations. Target archery is a whole different beast altogether.

Sent from my LGMP260 using Tapatalk

 

[BDZ65]

Well FOC determines the arrow Center of Gravity (C.G.), which is the point around which any arrow rotation occurs. With a higher F.O.C the vanes have a longer moment arm on which to act, providing more effective guidance and increased stability. Taking two arrows of proper spine: one with a 2% C.G. and one with a 10% C.G., the 10% C.G. will always be more stable. Seems to me that if you want to significantly over spine your arrow, go for it but it would never be a good idea to lower FOC to 2%.

 

[b0w_bender]

All the information you seek is out there so that you can understand what is going on. Most people never look.

Wizo-Oz
you are my hero great response!

 

[redbow26]

Great response whizOz. So how do you know how much FOC is perfect?

 

[whiz-Oz]

Great response whizOz. So how do you know how much FOC is perfect?

There is no rigorous scientific data which suggests that any specific FOC is better than any other.
There are an awful lot of anecdotes and beliefs which are largely confined to AT, while other forums around the world ignore it.
Most of the anecdotal evidence that I've ever seen reported is people changing their FOC by putting heavier points in, rather than actually testing FOC by moving it independently.
So they're not actually testing FOC. They're just testing heavier arrows and FOC.
If people can't be trusted to know what they're actually doing, you can and should automatically ignore any results that they get.
It's not WHAT you test, it's HOW you test.