Why FOC is only part of the story

[shafferm]

FOC is only part of the picture when it comes to stabilizing arrows in flight. The FOC measurement (actually center of gravity versus center of pressure which FOC is an approximation of) is fairly straight forward to measure. Rear drag stabilization provided by the fletching is the other factor at play and does not seem to get nearly the same attention as FOC. Increasing the amount of drag such as by increasing helix, going with larger fletchings, etc. will allow you to get excellent groupings even with low FOC %'s. The trade off with more rear drag is that it will be a bit noisier in flight and will start to slow the arrow faster.

Increasing your FOC usually means increasing your total arrow weight, which will give you a lower launch speed and will allow you to use very small fletchings, but can also give you excellent groupings as well.

So that seems to be the trade offs, either high FOC and lower launch speeds or high launch speeds and a bit faster decrease in speed and a tiny bit more air noise by increasing the rear drag.

Either method of arrow tweaking should be able to get you excellent groupings.

[Raymond]

That is an interesting read. It also helps me to understand more about the FOC measurement.
Thanks,
Raymond

[vixenmaster]

What would you think if'en i told you i can take bare arrows. Shoot groups small enuff with a BH at 30 yds to hit the Heart using Miss Vixen!

[Raymond]

I do not doubt what you are saying vixenmaster, now I am confused again, LOL. So what the heck is the fletches on the arrows for then. I am totally confused now.
Raymond

[vixenmaster]

Some BH's need help in rudder steering, like big fixed blade models. Fer every action there is an equal reaction. At longer distance a bare shafted arrow with BH may turn sideways & not recover! Its all about shooting yer model Bow to see what it does & likes. This modern thinking of young ppl. is i want my BH to hit where my field pt hits. Back when i started in the 50's field pt arrows were only to practice with to learn how to shoot yer Bow. Once i learned i set all my arrows up with BH's & learned where they hit & that was what i shot into sand piles at targets on the sand. The new ppl want something easy cause its too much work to resight-in fer yer BH's. Well now we have mech. BH's so they can do that very thing.

[Galgo]

Agree with Shafferm. Also think aligning broadhead blades with fletching is a myth that probably works against accuracy although I have nothing but theory to prove it.

F

[Limbs and Sticks]

I do not doubt what you are saying vixenmaster, now I am confused again, LOL. So what the heck is the fletches on the arrows for then. I am totally confused now.
Raymond

Raymond not all bhs will fly like Mike says, he has good ones that will, field pts will with out fletching's if the shaft is straight, you really run into probs with bhs, some need a little fletching work, I've seen some you can't make fly at all, those are rare if you can build a shaft, take a raw shaft and see for yourself.

Wes

[Ont_Excal]

Some BH's need help in rudder steering, like big fixed blade models. Fer every action there is an equal reaction. At longer distance a bare shafted arrow with BH may turn sideways & not recover! Its all about shooting yer model Bow to see what it does & likes. This modern thinking of young ppl. is i want my BH to hit where my field pt hits. Back when i started in the 50's field pt arrows were only to practice with to learn how to shoot yer Bow. Once i learned i set all my arrows up with BH's & learned where they hit & that was what i shot into sand piles at targets on the sand. The new ppl want something easy cause its too much work to resight-in fer yer BH's. Well now we have mech. BH's so they can do that very thing.

X2
I really don't care if my broad heads have same POI as field points.
I only want a consistent POI for each one out to 40 yds.
I don't shoot BHs until I get ready for hunting season.
Just my choice.

[bob1961]

What would you think if'en i told you i can take bare arrows. Shoot groups small enuff with a BH at 30 yds to hit the Heart using Miss Vixen!

yeah the higher FOC you have you can get away without vanes with small fixed BH's........bob

....

[Boo]

I'll use more vane offset rather than more FOC any day.

[Allan]

Have you ever thrown a bolt and made it spin A LOT as it flew? Like throwing it underhand and letting it spin off your fingers? The decelleration is drastic. That is the trade off. The reason you want the drag of the fletching is to open the operating window. In otherwords, compensate for errors.

Of course if everything is perfect, you don't need this "just in case" feature.

my $.02

[nchunterkw]

FOC also plays a part in penetration. When an arrow hits it's target, it flexes at teh balance point. Higher FOC moves ther balance point forward meaning a shorter distance between tip and balance point, meaning less flex, meaning less wasted energy.
Also, a heavier arrow, although it starts slower, will maintain a higher percentage of velocity downrange (slows down slower), meaning more energy when it hits it's target.
None of this matters too much when we are talking about any Excal crossbow and whitetails as just about any arrow I've seen discussed on here has plenty of energy to blow through Bambi out to 40 yards or so.
But if you are going to hunt a larger animal, like an elk, moose, buffalo, etc. it becomes more of an issue.
Bill shot an elephant with his Excal - but with a 900 grain arrow. Why so heavy? KE and momentum when it hit the elephant. He sure wasn't going for a fast flat shooting arrow, and didn't need too. His target size was pretty big.

For what it's worth................

[masboy]

I have the best of both a heavy foc of around 17 percent with a lot of helix with blazers on 460-500gr arrows and after sorting out the best shooting arrows these things will poke holes shot after shot if you do your part with field point and most broadheads with the same poi. I think it,s all about having the right combination and I have mine.

[See4miles]

What would you think if'en i told you i can take bare arrows. Shoot groups small enuff with a BH at 30 yds to hit the Heart using Miss Vixen!

No offense vixenmaster, but when you do this, are those arrows going in the target straight, or are they slightly sideways? Because I'm guessing they are a little sideways.

[Boo]

What would you think if'en i told you i can take bare arrows. Shoot groups small enuff with a BH at 30 yds to hit the Heart using Miss Vixen!

No offense vixenmaster, but when you do this, are those arrows going in the target straight, or are they slightly sideways? Because I'm guessing they are a little sideways.

Any amount of spine mismatch will cause angular flight. If you could match the spine to the bow you could get straight flight. Any amount of angular flight causes loss in penetration. Fletchings straighten out the arrow during flight and impact.
I believe Vixenmaster was trying to make a point not tell anyone that he hunts with bare arrows.