Tip for you Ultra-EFOC tinkerers

[chopx2]

I was sharing my observations with Dr. Ashby a few months ago and he pointed out the key to breaking the 30% barrier is not increasing point weight, but reducing tail weight.

The nock has the longest lever arm and you have the most to gain by reducing weight there. The QAD nock is a mere 4-4.5 grains. When I switched from a light 9.5gr nock I picked up 1-1.5% in FOC!!!! Just 5 grains on the tail did what I had add 50+ grains to the front to do without affecting spine or trajectory!

Get those arrows tuned to fly with low profile short feathers and a tiny nock and you will be amazed at the FOC increase!

BTW, the higher your current FOC the more you have to gain from lowering tail weight. It is not a linear relationship.

p.s. yes I believe the turbolator does work based on my personal trials.

[Night Wing]

You didn't state what type of arrow, material wise, you were shooting.

I have a feeling this only works in carbon arrows. It certainly doesn't work with aluminum arrows shot from low poundage bows (37#-42#) and long draw lengths of 30" or longer when dealing with a 32" BOP aluminum arrow.

[pickaspot]

It seems that EFOC became practical, almost necessary, with the advent of carbon. You never saw heavy heads back in the days when wood was the only choice.
Your suggestion is interesting. Do any of our TG sponsors carry the light weight nocks you mention? I suppose the opposite would bs true to adding weight on the rear with Lumenocks and the like...

[chopx2]

Pick a spot you are exactly right. The QAD nocks are available from a lot of places, but I don't know of any sponsors on here, but I'd love to find one.

Night Wing, these nocks only fit 5/16" carbon arrows. The priciples are the same regardless of shaft material. Carbon's stiff ness if an enabler because today's bows have cut in shelfs. If you look at ancient primitive archery societies FOC of 30% up to 40% was not uncommon, but their bows were wide increasing the dynamic spine of the arrow.

So in a sense we are relearning what subsistence hunters knew long ago.

Which came first...cut to center so we could shoot lighter faster stiffer arrows with less FOC or did cut in shelfs lead us to need carbon arrows because of reduced dynamic soine caused by the shelf...either way it is a system. Bow and arrow have to be matched.

[Guru]

:rolleyes:

[Night Wing]

Chopx2,

I use Easton Super Nocks. It's basically an 11/32" nock and it weighs 13 grains. I'm also shooting 3, 5" parabolic feathers. The Super Nock is attached to my 421 grain 2212 Easton Eclipse X7 aluminum arrows cut to 32" BOP.

With a 75 grain point weight, I wanted to know what the FOC number is and it comes out to 9%. The trade off is in GPP (grains per pound) and this gives me a 10.02 GPP arrow when shot out of my 42# bow. With my 37# bow shooting the same 421 grain 2212, it comes out to a 11.37 GPP arrow.

There is no way a 5/16" nock can be fitted to a 22/64" (11/32") arrow. But for discusson's sake, lets say it could. And I'm even going to go smaller with a 1/4" nock with 3, 3" feathers further reducing tail end weight.

One of Easton's smallest nocks is a G nock and it weighs 7 grains. It's also a 1/4" nock in size. If it were possible to afix a nock this size to a 2212 aluminum arrow (and again it isn't possible), reducing the tail end weight from 13 grains to 7 grains from nock weight alone and also having 3, 3" feathers instead of 3, 5" feathers, would give me an FOC of 10.5%. The gain is just 1.5% and this is predicated on a 75 grain point weight. But again, if I reduce tail end weight, I have to reduce point weight to 65 grains to compensate for the loss of tail end weight because aluminum arrows are not as stiff as carbon arrows. This would reduce the FOC to (9.5%). There is no way anyone shooting an aluminum arrow; no matter what size in spine, no matter the point weight, no matter the length of the arrow, no matter the poundage of the bow, is going to give them a properly spined aluminum arrow with correct point weight, to give them an EFOC of 30%.

You're telling me the principles are the same regardless of arrow material, but I deal in "reality", not principles. When it comes to aluminum arrows, I'm sticking to my guns and I'm going to reiterate that no one shooting an aluminum arrow for bowhunting is going to have a 30% EFOC arrow. I've learned a lot of things shooting aluminum arrows during my 47 years of bowhunting. The things I've learned have come from hands on experience from experimenting with aluminum arrows shooting 2013s, 2113s, 1916s, 2016s, 2018s, 2114s, 2115s, 2212s, 2213s, 2215s and 2117s out of my low poundage bows with my 30" draw length shooting 32" BOP arrows.

If you want to refute my statement, make a poll on Trad Gang for aluminum arrow shooters and see if anyone is shooting an aluminum arrow with a 30% EFOC. If you take me up on my offer to make a poll, I think you'll be hard pressed to find "one" person.

In closing, EFOC is the exclusive realm of carbon arrows, not aluminum arrows. Although I don't shoot wood arrows, I have a feeling anyone shooting wood arrows doesn't have a 30% EFOC arrow either.

[Bobaru]

Chop - you have some interesting ideas.  But, I think I'll pass.  I've attempted a number of tests to demonstrate to myself that increasing FOC increases penetration.  I have been unable to produce any correlation.  

Plus, I can't seem to wrap my head around the idea of disrupting the air flow over a wing.  I suppose that would work as a brake.  But, I don't really need a braking effect that I know of.

Thanks anyway.

[amicus]

Hey, Chop

Thanks for sharing thats a great Idea.

I think the basic principles of EFOC applies to any type of arrow, its just a lot easier with carbons.

Gilbert

[Bobaru]

Nightwing, you're correct.  This whole issue of "hign FOC," "EFOC," and now "Ultra-EFOC" only came into existance with carbon arrows because of their increased stiffness versus weight.

With aluminum, as you become more and more stiff, the weight of the entire arrow increases.  One gets to a maximum of about 17% to 19%.  Some have said a little higher.  Fine.  But that's about the highest you will get and still have a tuned arrow.

On the other hand, Chop may have a point with bows that don't have shelves allowing the earlier archers to have higher FOC and still be tuned.  I'm not sure where that limit was/is.  

But, frankly, I'm not much interested because nobody can demonstrate the effectiveness of higher FOC.

Ashby rightly says all his work is not scientific.  That's fine.  That just means he only has an opinion.  That's okay too.  But, it means his opinion is not anymore supported by evidence than anyone else's.

So, if I were you, I wouldn't get too worked up on the subject and just continue shooting the arrows that work for you.

[Don Stokes]

Using short, low profile feathers on hunting arrows is a BAD, BAD idea, no matter what your FOC. Please don't encourage such behavior.

[hvyhitter]

Gee, maybe those "old guys" that were shooting tapered wood about 70 years or so ago knew a little more about whats what than they were letting on. I can testify that a 750 gr tapered maple has no penatration problem even when tipped with a big ol'snuffer and shot out of a slow hill bow............

[SlowBowinMO]

Carbons are awesome for point loading, but woodies will indeed point load well also.  I haven't tried to take them as far as carbons yet, mostly because the shafting is usually heavier.  Aluminum's don't seem to like it at all.

[ChuckC]

Why can't a 5/16" nock or even smaller go on an 11/32" shaft ?  
ChuckC

[Night Wing]

The highest FOC percentage I've ever had shooting a very heavy 637 grain 2117 aluminum arrow, with a 235 grain point weight, out of my 42# bow was 17%. The only way I could achieve this high FOC percentage was by lowering the brace height to give me a longer power stroke.

This is why I know if anyone is shooting an aluminum arrow, EFOC and ultra EFOC isn't possible.

[wtpops]

Originally posted by Night Wing:
You didn't state what type of arrow, material wise, you were shooting.

I have a feeling this only works in carbon arrows. It certainly doesn't work with aluminum arrows shot from low poundage bows (37#-42#) and long draw lengths of 30" or longer when dealing with a 32" BOP aluminum arrow.

Yep and you lose a lot more options than just efoc with a long draw, 31" draw and 32" arrow here. in my case draw lengh dictates what i will end up with and the options are few. Im not complaining i like my draw i just cant play with things like the rest of you guys. So i just get her flying stright and true and injoy the flight of my so so foc arrow. But i do wish i could play, it is fun to tinker.

[JohnV]

"Ashby rightly says all his work is not scientific. That's fine. That just means he only has an opinion. That's okay too. But, it means his opinion is not anymore supported by evidence than anyone else's"

I strongly disagree with your statement.  Dr. Ashby has conducted some pretty extensive studies looking at penetration on dead critters and the effect that FOC plays.  This is not someone's random opinion...it is one based on a lot of field studies conducted in a scientific manner and being as objective as possible.  To say that his opinion has no more basis or support than those who disagree is laughable.  You don't have to be one sharp broadhead to recognize this.  Where are the studies to refute his observations?  Some guy shooting three arrows into a hay bale in his back yard?  When Dr. Ashby says his studies are not scientific his words get deliberately twisted by his nay-sayers.  He is simply acknowledging that shooting a dead animal under field conditions is a bit different than some type of lab experiment where a uniform material is shot under better-controlled conditions such as a bow held in a mechanical device with a triggered mechanical release.  While not perfect, Dr. Ashby's results definitely show clear trends regarding how different parameters affect penetration.  Those who feel threatened by his work may choose to ignore his reports.  Many of us have an open minds and are willing to listen to ideas of building a better performing hunting arrow.

[JimB]

After reading this,it dawned on me I have some 2016 and 2018 aluminums tuned to a few of my bows.I had never checked the FOC.The 2016 has a 100 gr insert and 145 gr point.FOC is 19%,total weight,573 grs.The 2018 has a 90-something adapter and 175 gr point and FOC is also 19% and total weight 650 grs.I hadn't been interested in FOC when building these,just got them tuned.I am surprised it was that high.For sure,19 % is all I could squeak out of aluminums.I can't cut 1/8" off.Sounds like you guys were right on the money.

[Beanbag]

WTPOPS, Lots of insight there,Jim G

[Don Stokes]

When Dr. Ashby says his work is not scientific, I believe he means it wouldn't pass peer review of other scientists for publication. Standards are very high for such endeavors, and as a former research scientist myself, I understand. It doesn't mean his work is without merit, it just means that it's unlikely that it could be replicated by others, or be accepted for publication in a scientific journal. Who else has the access he has to the testing media, and the archery skill to conduct the tests?

Whole animals are not a good test medium because of the high variability in the density of the parts the arrow passes through. To pass peer review scrutiny, the sample sizes would have to be enormously large, much larger than anyone would be willing to do. His work is fascinating, and there is much information to be gleaned from it, but it's still not "scientific" in the world of research scientists. It could only be considered anecdotal as best in that world.

[Jason R. Wesbrock]

JimB & Night Wing,

If you're going to chase EFOC with aluminums, you'd want to start off with a larger diameter, thinner walled shaft. Using a shaft with a wall thickness of .016, .017, or .018 would be counter productive to increasing FOC.