DEERSLAYER wrote:I think your making assumptions that all other things remain static. Your not taking into consideration how big of a drop in the arrow speed is affecting the numbers you are putting into that formula or the fact that bows transfer energy to a heavy arrow more efficiently than a lighter one. It's easy to change speed. Just buy a different bow.
I am aware that the velocity of the arrow will drop with increasing the weight. That goes without saying.
But the KE transferred to the arrow has to be a direct Function of the potential energy stored at full draw. There should be very little difference in the KE value of a heavy arrow compared with a light arrow as a result. The next post down has some results that clearly indicate that in fact the energy transfer is a little bit more efficient with heavier arrow.
Follow this logic for a moment. Two arrows leave the same bow with the same KE. One Is it lighter and faster, the other heavier and slower. Since their velocities were squared to obtain that KE
E = 1/2mv2
It follows from the momentum function where the velocity is to the power of one only to obtain a value,
P = mv
That momentum will forcefully be greater in the heavier arrow with the same KE but slower trajectory.
If what you want is an increased chance for pass through, then this can be achieved simply by selecting a heavier arrow for the same bow (and saving your $, unless of course you want a new "shiny" bow, which is another consideration altogether).
On the other hand a faster bow will obviously produce grater momentum in the same arrow, but how much. When you read the literature on a bow, they use the KE value to quantify their bows. It makes sense because this value should be relatively consistent regardless of your choice of arrow weight. However I think that overall this value is misunderstood, and at least a little misleading for your average hunter. Looking at the values from your other post, comparing a 70 lb bow shooting a 500gr arrow at 280fps with 87ftlbs energy, with a 60 lb bow shooting the same arrow at 260fps with 75ftlbs energy. That 20 ftps more provides an extra 12ftlbs energy, or 12/75 = 16% more. But from a momentum perspective, given the linear relationship with velocity, 20/260 = 7.7% more. That is how much more your increase in pass through potential you gained by increasing the limbs on that bow from 60 to 70 lbs. It isn't insignificant, but it is far from substantial.
DEERSLAYER wrote:Have you ever heard of Norb Mullaney?
No. Should I have? Who is he.
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