Flight with FOC %

[Margly]

Hi!
Here is a question for the high FOC shooters.

Will two arrows with the same weight but different foc % have similar drop in flight/distance?

Here is my ex:
I`m shooting a 430 gn Arrow from a 45@drawlength With 19.3 % foc and sees it drop dramatically at ca 35 yards.

Would a same spine and weight arrow have the same drop if the foc % is near at ca 9-11% foc?

more weight in front will make the arrow`s energy more pressed to the ground? Wouldn't it?

     :confused:
 
Margly

[-snypershot317-]

yes they will fly differently. you want as much weight at the point as possible for a number of reasons. first off a higher weight up front will allow better recovery of arrow which means better flight and straighter flight. another reason is for a pulling motion than pushing motion when the arrow hits said target (elk, deer, pig or whatever critter your hunting    ) this means more energy is used to pull the arrow rather than push the arrow which allows for better penetration. now lets say the opposite is true where most of the weight is not at the point. you will have inconstant flight patterns because it is harder for the arrow to recover, and penetration will be almost nonexistant because the energy from the arrow will be used up just trying to push the weight into the target...my arrows have nearly 250 ish grains currently up front and are extremely accurate; the foc i think is somewhere around 12-15% if i remember correctly. dr ashby i think did a good amount of research on this and if i hope others will correct me if im wrong on my post. i hope this helps, Jesse

[Kmurray]

External ballistics depends on quite a few variables, however your "FOC" is not one of them...

 "FOC" (as applied here in archery) could throw off your projectiles balance, and thus hurt the trajectory, but if tuned properly.....
a projectile with the same weight, same velocity, and same coefficient of drag, having the same external variables in effect (such as atmospheric conditions/wind/humidity/etc) will have the same trajectory...

Now, the whole FOC thing is not so much about trajectory, but more so about the whole kinetic energy VS momentum as the projectile travels through medium (tissue, i.e. animal).
According to some, the high FOC will allow for better penetration through said medium, but no such claims have been made that the FOC would improve/impair the arrows trajectory...
In fact one of Dr Ashby's repots indicated that many steer away from the high FOC because of the misnomer that arrows with a high FOC will take a nose dive. He illustrated in his testing that the difference in trajectory from a standard FOC, HFOC, and EFCO arrow was minimal at best and for most purposes inconsequential... as long as everything was in TUNE and all external factors were equal.

Just my 2cents....

[jamesh76]

Interesting post.       Just curious how high foc differs from wood to aluminum to carbon?

[Friend]

My 30% Ultra-EFOC tuned arrows seem to share the same mark at ~40 yards as related to ~19% high FOC arrows of similar weight. Note: utilize a 5 1/2 X 3 fletch and you may likely see a difference.

Have not tested them against normal FOC shafts and would not expect any significant difference provided both shafts were properly tuned.

[katman]

Same mass, same speed, same drag, both arrows hit ground at same distance. High foc arrows do not nose dive.

Now being a stiffer spine the higher foc should stabilze quicker loosing less speed and may fly further.

[Flying Dutchman]

I am a 3D archer and found out that high FOC arrows DO nose dive at the larger trajectories. So I use around the 9 to 10 % for years now .  This became very evident at a tournament we had in Germany last year.
One guy used EFOC carbon arrows and you could see very  clearly the difference between the flight of his arrows and ours. We used around the 10 % foc, he was around the 25. His own comment was: " compared to your arrows, mine drop like rocks!"  He had great difficulties in hitting targets above the 35 yards.
However, high foc also means higher weight. So it is possible it was the just the higher weight which played tricks upon him.

[Flying Dutchman]

Interesting stuff though...

Here is an example which explains it.....

Suppose you want to shoot low FOC.  Let's say you shoot a 50 lbs bow. You use a certain spine value, you tune your set-up and a 100 grains front load gives you the right flight.
That means 2 gpp for your front load only.

Now you wanna have a high FOC arrow. You need a stiffer shaft, because more front weight makes your shaft weaker. So You pick a shaft with a higher spine value and start to tune. Now you need a front load of 250 grains to get your set- up tuned.
This means 5 gpp for your front load only. Most of the time, higher spine value means a heavier shaft, let's say 1 gpp at least.

So all together, your EFOC arrow will be 4 gpp heavier.

So let's  say you will have 9 gpp for your low FOC arrow and 13 gpp for your EFOC arrow.
This will cause a huge different in speed, thus in flight, especially for longer ranges,

If you did your tuning well, your dynamic spine will be the same, meaning the two different arrows will recover equally fast.

The EFOC will give you better penetration, the low FOC will give you a faster flight with no nose drop at bigger distances.

That's my 2 cents.....

[onewhohasfun]

Katman has it right.  Same weight, equals same speed, equals same distance travelled. Flying Dutchmans example is 2 diff. weight arrows.
Never been a big fan of gravity. It causes all kinds of problems.  

[Flying Dutchman]

You will have a hard time making arrows with EFOC and low FOC who are equal in weight    and tuned for the same bow of course.

[katman]

Originally posted by Flying Dutchman:
Interesting stuff though...

Here is an example which explains it.....

Suppose you want to shoot low FOC.  Let's say you shoot a 50 lbs bow. You use a certain spine value, you tune your set-up and a 100 grains front load gives you the right flight.
That means 2 gpp for your front load only.

Now you wanna have a high FOC arrow. You need a stiffer shaft, because more front weight makes your shaft weaker. So You pick a shaft with a higher spine value and start to tune. Now you need a front load of 250 grains to get your set- up tuned.
This means 5 gpp for your front load only. Most of the time, higher spine value means a heavier shaft, let's say 1 gpp at least.

So all together, your EFOC arrow will be 4 gpp heavier.

So let's  say you will have 9 gpp for your low FOC arrow and 13 gpp for your EFOC arrow.
This will cause a huge different in speed, thus in flight, especially for longer ranges,

If you did your tuning well, your dynamic spine will be the same, meaning the two different arrows will recover equally fast.

The EFOC will give you better penetration, the low FOC will give you a faster flight with no nose drop at bigger distances.

That's my 2 cents.....

Wise choice of components can yield very high foc but still keep overall weight from getting to high. One of my setups has 29.3% foc, total weight is 580gr and is 11gpp.

Remember you must compare SAME weight setups, some build efoc that may weigh 14gpp and complain they nose dive at longer distances. Shoot a low foc 14gpp setup and it will also drop just as quickly. It is a fallacy that high foc nose dives, in my experience, all else being equal.

[katman]

Originally posted by Flying Dutchman:
You will have a hard time making arrows with EFOC and low FOC who are equal in weight     and tuned for the same bow of course.

With today's wide range of carbon shaft weights I think you could get pretty close, but since I have no desire for a 'normal' foc and not enough $ its not for me to try.

[Manitoba Stickflinger]

Equally tuned arrows out of the same bow that weigh the same should have the same cast. I too shoot arrows loaded up front but have to say they really do not like cross winds.

Like Flying Dutchman, if I were a 3D or tournament shooter, I would shy away from high FOC. That may be the reason for the drop that he claimed happened with another shooter with higher FOC arrows. With the light back end of the arrow, it is easily manipulated by the wind and therefore flying less efficient than the more evenly weighted arrow.

I shoot most game at under 15 yards in heavy cover so the wind is almost never a variable. If I one day chase antelope of mulies, I'll be shying away from my higher FOC set-up.

[BenBow]

Here's Dr Ed's demo on foc & arrow flight.
   

[Kmurray]

Originally posted by katman:

Wise choice of components can yield very high foc but still keep overall weight from getting to high. One of my setups has 29.3% foc, total weight is 580gr and is 11gpp.

Remember you must compare SAME weight setups, some build efoc that may weigh 14gpp and complain they nose dive at longer distances. Shoot a low foc 14gpp setup and it will also drop just as quickly. It is a fallacy that high foc nose dives, in my experience, all else being equal.

This is exactly right

If one read's the reports, or watches the video's by Dr Ashby, you will notice that he emphasizes that, front loading the arrow is NOT optimal way to get the FOC up...
In fact Dr Ashby spends a great deal if time demonstrating the very basic concept of the lever, where removing small amounts of weight from the REAR of the arrow has far more effect on the FOC than just adding point weight.

Removing 10gr from the rear of a 30" arrow (lever) by using a lighter nock, smaller lighter fletching, and no cresting or wrap, (or even a taperd shaft in the event of wood) will have a much greater effect on FOC that adding 10gr or even 20gr at the tip.