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- Sep 14, 2020
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I didn't mean to imply that speed isnt a factor.
What I was trying to say is, in regards to penetration, there is more to be gained by heavier and slower than there is to be gained by lighter and faster. Dropping ~100 grains to gain ~50 fps for ethically realistic bow ranges is the wrong approach, not just in my opinion, also well proven by the vast testing and experiments done by Ashby.
This point has been discussed countless times and analogized (is that a word?) by comparing golf balls to ping pong balls and semi trucks to compact cars. Heavy hits harder than lighter.
The main issue is where is the hunter's threshold for trajectory?
Seems like too many guys have a threshold for a certain fps with little regard to arrow weight.
I have some friends like that..."I need to stay above 275 fps". Why? What is magic about the 275 threshold?
Now, there are (proven by Ashby) magic numbers when it comes to TAW and FOC.
I think this is possibly the wrong approach, comparing archery hits to golf balls and semi trucks. These are collision problems (in physics).
While bullets can move fast enough to create shock waves upon collision that can cause catastrophic physical damage to game animals (KE is a sensible consideration there), arrows move too slowly.
What we want is for an arrow to slice through an animal, not to impart work on it. We don't want to move tissue/bone, we want to cut through tissue/bone with as little resistance as possible.
In this scenario, what we're up against is counter forces. When we launch an arrow, the bow imparts a force on that arrow. F=ma. Newton's 1st law tells us that arrow would stay in motion indefinitely unless acted upon by other forces, so we have an inertial force of....F=ma, yay! It's up to other forces to slow and stop that arrow.
Those forces include gravity and wind, but more importantly friction, suction, and pressure as an arrow traverses an organism, or attempts to do so.
Isolating the likely greatest counter force, friction, we have then two frictional forces, static and sliding. Considering those forces is a very different problem than the major forces in standard collision problems.