On a post on a different forum a gentleman made the comment that the stiffness of the arrow's spine and not the mass weight of the arrow is what determines how much energy is imparted into it by the bow.

What are everyone's thoughts on this comment?

PHHHBBBBBTTT![8D]

There is nothing in the KE or momentum formulas that takes stiffness into account.

However, he does have a point. An arrow that's underspined will not absorb as much energy from the bow, because some of that bow's energy will be used up by making the arrow flex. It will also enounter more wind resistance as it worms around in the air before it stabilizes, which bleeds off some of the energy it does take from the bow. Not to mention terrible accuracy.

An overly stiff arrow will not flex as much and it will stabilize sooner, which will give it better energy than the underspined arrow. But, again, accuracy becomes an issue.

He is wrong!!!

It is a combination of both.

That noise and vibration you feel with super light arrows is energy - energy that did not make it to the arrow.

Thanks for the comments guys. My thoughts exactly but I needed to hear someone else say it.

Arthur,

I had you in mind when I posted this because the arrows that were being discussed were those 5 grains per inch shafts that High Country has been promoting.

The stiffer the arrow the more energy it is going to have. The heavier the arrow the more intial energy it will have. Yes stiffness is not in the KE equation, but it does matter.

Frank, I went over there to give 'em my 2 cents worth, like you asked. Wound up giving them a whole nickle's worth though.

It must be negligable, or they would throw it into the KE equation