High FOC question

[snowplow]

I think I am getting a better handle on this. But I have one question.

Say you have two arrows @ 550 grains total. (10 gr/# for a 55# draw)

One has a 250 gr tip package and a 300 gr shaft.

The other has a 130 gr tip package and 420 gr shaft.

I am trying to illustrate a conventional vs high FOC arrow situation. Since both are identical weight on a scale, would the trajectory be the same?

[Kris]

That's a touchy subject.  Dr. Ashby just demonstrated in a seminar with two same weight arrows, the one with the higher FoC actually flew further, all else being equal.  I believe it has to do with quicker stabilization, hence, greater efficiency aerodynamically.

I am skeptical but am also amused.

Watch:
       

Kris

[snowplow]

That seems valid. It seems to make sense to me that stabilization would be much better/quicker with high FOC. Basically for some reason it just seems hard to picture a 250 gr tip having the same 'drop' as a 125 no matter how light the arrow. Although it seems to make sense on paper it just seems wrong =)

[R. W. Mackey]

You won't notice any difference at Hunting Yardages. You will
Notice quite a difference in penetration. Now if you really want to see some penetration get that weight up around 12 to 14 gr.
Per # of bow weight.
  RW

[Bjorn]

Kris said: 'I am skeptical but am also amused' love it!!  

[maineac]

I think our brain relates to FOC from personal experience.  If we hold heavy things out, or carry children on our shoulders we feel unbalanceed and want to fall forward.  How that works on an arrow in flight is different. I have experienced no nose dive from my FOC arrows,  Overall mass has an effect over 25 yards, but tip weight does not appear to affect it.

[katman]

"would the trajectory be the same?"

YES! at typical hunting ranges.  High foc does not nose dive.

[snowplow]

Thanks guys. I am a little confused still on one specific.

It sounds like you guys are saying that it wont change trajectory at short ranges but will at longer ones.

So if I am understanding correctly, that is saying 'yes' trajectory will change. It just might not be noticeable at short range.

Although I know that sounds 'right', I dont understand how (on paper) the same weight arrow should have a different trajectory?

Am I off on something here?

[damascusdave]

I think what people are saying is that higher FOC arrows will stabilize quicker than less FOC ones...what that seems to mean is that less energy will be lost and in fact the higher FOC arrow will retain more velocity...higher velocity for the same weight will always give flatter trajectory...not a lot, just a bit...I shoot arrows with a wide range of FOC and I am just not a good enough shooter to tell the difference...I tend toward moderately high FOC, say around 15% for hunting

DDave

[Kris]

Don't get me wrong, I am a huge FoC guy and incorporate it on all my arrows and know all the advantages it brings.  Where it really becomes interesting is in Flight Shooting, of which I have no experience.

If you haven't watched the Ashby You Tube video I posted above...give it a look.  It is interesting to say the least.

I am actually lightening my arrows a bit this season, more like 10 - 11 gpi.  Accuracy and trajectory are better, even at hunting distances < 20 yds.

As O.L. Adcock says, you can have high FoC and still have a light arrow, don't clump the two together.  Having mentioned that, I still prefer to error on the "heavier" side for arrow weight per pounds draw weight.  Ultimately it has to come down to arrow flight and accuracy.

Kris

[Pete McMiller]

Dustin,

In theory, assuming both arrows are the same weight and shot from the same bow, the trajectory will be identical.  But the one variable that is more difficult to quantify is the efficiency of energy transfer from the bow to the arrow.  With our two identical wt. arrows, if one is 100% efficient and the other is 80% then the first arrow should have a better trajectory.  One of the significant parameters in obtaining more efficiency is reducing the amplitude of the oscellations called archer's paradox.  Increasing the FOC on a perfectly spined shaft is one way, adding 5 1/2" fletching is another.  Obviously increasing the size of the fletching, while reducing the amplitude of oscellations also robs the efficient transfer of energy.

Ideally, a perfect arrow will have all the wt. up front and no fletching but that is impractical even for target uses.  So, we compromise by adding enough fletching to stabilize broadheads in adverse conditions while maintaining the highest transfer of energy efficiency.

In my case I have gravitated to an arrow of 645 grains and 31.6% FOC that flies like a laser even with big Grizzly Kodiak broadheads.

It's all about tuning but there is way more to it than many people realize.

[Kris]

Well said Pete!

Good to hear from you!

Kris

[Scarne]

My experience has been similar to Pete's.  That said I'll go a bit further and say that my trajectory with HFOC (22%) is flatter further, by about 5 yards.  That's not to say that it is the same for 5 additional yards but that the rate of drop over same distance has not been as dramatic as before I shot the HFOC set-up.  I attribute that to faster recovery off the shelf.

There can't be any other practical answer as weight distribution is the only variable in the equation.  All the other inputs are exactly the same.

Within 20 yards I can't really see a difference from two shafts of equal weight. BUT I can see a difference in how the shafts come off the shelf.  The HFOC set-ups do stabilize faster.  Stabilization equates to retained energy and thus better penetration.  The stabilization is visible with decent lighting as long as you focus on your follow through all the way to the target.  

I shoot 53@29" with a 695 22% FOC grain arrow.  After shooting this set-up for three years I'm reasonably convinced that on a 140 pound whitetail at close range with a Grizzly BH I could crush both shoulders or sever a spine within 15 yards.

Save the ethical remarks about shoulder shots for somebody else.  You hunt long enough you are going to hit a shoulder, and cripple a deer.  Nothing ethical about that is there?  Might as well have a set-up that get's the job done should that happen.

Good luck this fall gents!