Another question for the tech gurus: I know arrows have both static and dynamic spine characteristics. I also know that arrow spline refers to the “stiff” (less resistant to flexing) side of the arrow shaft. In older carbon composite arrow technology, this came from the over-lapping procedure during shaft manufacture. Wooden arrows exhibit this phenomenon due to the grain formations of the growing plant. I have read one way to determine the spline of a composite shaft is to plug both ends of a shaft and float it in water. The side that faces up is the light side and the down facing side is the heavier (and therefore stiffer) side of the shaft. I have also read of adjusting (rotating) the nock on composite shafts to “tune” all of your arrows to leave the bow consistently thereby producing better groups. If the “bathtub test” can be applied to modern composite shafts, would not the lack of wall concentricity produce rotational imbalances negatively impacting group sizes? In the realm of firearms, this problem was dealt with by the application of rifling imparting rotation to the projectile. Archery tries to deal with the issue by use of imparting rotation through offset or helically twisted fletching. Firearms research has found projectiles of differing weights and velocities require different rates of spin imparted to the projectiles to achieve optimum stability. Experimentation has shown that “over stabilization” and “under stabilization” produces poor accuracy. I would imagine that archery projectiles would benefit from research along these same lines and wonder: Has this research been performed in the archery industry?
Konrad, You've got to remember that rifle ballistics and archery ballistics are an order of magnitude in separation from one another both in velocities and accuracy standards. If I can hit a fly's butt at 10 yards with an arrow I'm happy whereas I wouldn't be happy with that accuracy in a rifle at anything less than 100 yards. You'd put way to much effort into the arrow testing/tuning procedure with very limited results in comparison to other areas that would return higher end results like learning to shoot better. Good thinking, but not worth the time IMHO.
I can't imagen it making a group significantly any better. so much depends on form & consistency in archery. you could have the 'perfect tune' yet have you're form off ever so slightly & it would destroy the extremely minor if any advantage of this 'perfect tune'... it's not hard to robbin hood arrows on purpose at 20 even 30 yards, I can't imagin a group getting tighter than that, even with this super uber perfect arrow really good to see some think outside the square though
The lighter (tail) end is the stiffer of the two. You should do this no matter what. On some bows you must do this in order for the arrow to clear the rest/bow without contact.
When I made the comment, I was referring to a “standard” non-tapered or straight walled shaft. If we are discussing tapered shafts, the single taper type with a heavier frontal wall thickness is actually stiffer than the thinner tail section. The idea behind the thinner tail section is to aid in the reduction of oscillation after firing and achieve stability sooner (less mass moving). It is well known that an arrow with a higher front of center balance point also promotes penetration in hunting applications. Easton also produces a double tapered shaft “barrel taper” (thinner at the front and rear) for the same reasons. However, because they are strictly target shafts they do not need the strength for supporting heavy broadheads during launch and their associated impact energies.
The CX shafts, from the copied ad above, are actually a straight/standard taper shaft. They just throw a layer of camo on the front 3/4 of shaft that they call "buff tuff" and say that gives them more FOC. I've compared them against their older non-"buff-tuff" shafts and they are the same. Their FOC increase claims are pure marketing BS. No measurable increase in FOC and no difference in flight characteristics.
Thanks for the input. I have read the same about that manufacturer's shafts in previous posts. Easton and Alaska Bowhunting both make ACTUAL tapered shafts. Camo tape would have no effect on spine distribution but would tend to give a more forward center of balance point.
I've got some of the Grizzly Stiks. I only shoot them off the shelf of my trad bows so I really haven't played with what they're capable of. I've been more concerned about getting the spine right than anything. One thing about shooting them out of a compound is that they're hard to tune since the initial rest set-up has to be done for the fat end of the shaft which can only be lined up perfectly at full draw. It requires some guess work on set-up and then a bunch of adjustment during the shooting process to get fine tuned. They are actually measurably heavier in the forward end of the shaft though unlike the CX which is BS. I'm not sure that the barrel taper of the A/C/E shafts would gain the hunter anything (especially at that cost!) but it looks like you've thought that through as well.
