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My next step, arrows

Petrichor said:
Here’s the deal the only way to increase kinetic energy is to manipulate either mass or velocity. If you double the mass of an object you double its kinetic energy. However because kinetic energy is proportional to velocity squared, if you double an objects velocity you increase its kinetic energy by four times. Velocity has an exponentially greater effect on KE than mass. However mass definitely is half the equation. I just made myself laugh.
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That's pretty much what the guy was talking about on the podcast. This is where it ties back to what @JSEXTON23 was talking about as the arrow moves down range. I hope I relay this right but a light arrow and a heavy arrow set up for a particular bow will leave the bow with virtually the same ke on a pct basis. The heavy arrow though slower will carry more ke at distance.

To me that is saying if ke is energy to do work and momentum is work, heavier wins. The question then becomes what defines the entry to heavier as it relates to penetrating ribs and scapula, using the assumption that we put the arrow in the right spot. I have a number in my head based on my, as @Allegheny Tom would call it, anecdotal data. :) Would be curious to know how close it is to what testing determined.
 
Heavier bullets carry energy and velocity better at longer ranges because of momentum. While KE is greatly influenced by velocity, there is an upper limit on velocity. You cannot continue to double arrow speed indefinitely. You can however, easily increase mass. If you shoot an arrow at 200 FPS at weight = x, you would have to add ~83 FPS to double KE. That is not easy to do. However, if you shoot an arrow that weights 350 grains, you can easily double that weight. You will lose velocity, but if you play with the numbers, you can generally end up ahead in KE and momentum adding weight. There is a sweet spot and many factors. However, back to my original statement, momentum helps keep velocity down range. Wind resistance and all other disturbances would be equal for a heavy arrow or light arrow, but inertia will be greater in the heavy arrow and it will therefore overcome those disturbances easier.


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BTaylor said:
That's pretty much what the guy was talking about on the podcast. This is where it ties back to what @JSEXTON23 was talking about as the arrow moves down range. I hope I relay this right but a light arrow and a heavy arrow set up for a particular bow will leave the bow with virtually the same ke on a pct basis. The heavy arrow though slower will carry more ke at distance.

To me that is saying if ke is energy to do work and momentum is work, heavier wins. The question then becomes what defines the entry to heavier as it relates to penetrating ribs and scapula, using the assumption that we put the arrow in the right spot. I have a number in my head based on my, as @Allegheny Tom would call it, anecdotal data. :) Would be curious to know how close it is to what testing determined.
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Is this what you are looking for for "minimums"?
Taken from The Ashby Bowhunting Foundation site.
Screen Shot 2021-08-10 at 2.59.36 PM.png
 
BTaylor said:
Dont recall ever seeing that or even seeing anyone reference it. Thanks for putting that up. No argument with that chart at all.
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You bet.
There is so much Ashby info out there and it isn't all found in one place. Its a chore to find it all which I think often leads some guys to form conclusions with only a portion of the info.
 
johnfajitas said:
Heavier bullets carry energy and velocity better at longer ranges because of momentum. While KE is greatly influenced by velocity, there is an upper limit on velocity. You cannot continue to double arrow speed indefinitely. You can however, easily increase mass.
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Great post! I slightly disagree. You can’t double down on mass indefinitely either. There is a reason the 50 cal is no longer the king of the long shot. Several big but not too big calibers take the cake now. KE is more influenced by velocity than mass, but let’s be honest. We can’t add gun powder to our arrows. We stick to our draw length (hopefully) and literally the only thing we can really play with is mass. Whether by length, point, insert, feathers, nock, etc, we really aren’t really playing with velocity directly. Our velocity changes based on the mass and the draw length which hopefully remains constant. We aren’t really adding anything to the equation if we remain consistent. If we could add more velocity without changing mass, now that would change something. I go back to my earlier statement. Everything is a trade off. Based on the fact that likely a draw will remain constant, and if we use same bow then bow remains same (unless we change something). Then technically every change we make outside of small changes like string material and new form, only really change mass, which in turn changes velocity. Have hope though. Because of this there is a balance. And there is a most efficient setup for the user and bow. That means there is such thing as too light and conversely such thing as too heavy. Yes you can over do it. I can tie brick to my arrow but even my recurve won’t launch it but a few feet. That said I largely agree with the chart, but for the OP sure her arrow will kill animals no problem, and I’m glad it flies great. Have fun and good luck out there OP! But since she asked for thoughts and such in her post. I still think it overly heavy for the bow. To the nay sayers that say she won’t shoot outside of 20, ok, however if you want to be perfect at 20 do you only practice at 20? To be confident there I would practice longer too. IMO. I like the chart shown above but it is overly simplistic. I’m more interested in the actual data behind it. Your mileage may vary. I do appreciate this conversation though and I certainly hope it is helpful to all.
respectfully,
D
 
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I don’t think 16 gpp is even remotely approaching the brick on your arrow scenario. I know that’s not the comparison meant by that comment. My point is I do not believe 12-16 gpp have reached a bow’s point of diminishing return when it comes to efficiency or energy transfer. I need to do some digging but I believe the Rocket Man might have mentioned something regarding 20 gpp not even being the point of diminishing return.

Ashby was on Meateater recently and he talks about 6 feet of penetration on an Eland with a 40# bow and something like a 24” draw length. Sure, compound, but I believe it would be comparable to a 40-42# bow drawn 27-28”. I can’t recall the arrow weight, but it wasn’t 8-10 gpp.
 
JSEXTON23 said:
I don’t think 16 gpp is even remotely approaching the brick on your arrow scenario. I know that’s not the comparison meant by that comment. My point is I do not believe 12-16 gpp have reached a bow’s point of diminishing return when it comes to efficiency or energy transfer. I need to do some digging but I believe the Rocket Man might have mentioned something regarding 20 gpp not even being the point of diminishing return.

Ashby was on Meateater recently and he talks about 6 feet of penetration on an Eland with a 40# bow and something like a 24” draw length. Sure, compound, but I believe it would be comparable to a 40-42# bow drawn 27-28”. I can’t recall the arrow weight, but it wasn’t 8-10 gpp.
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I agree and personally hunt approximately 13 gpp. 20 gpp is a lot and I have noticed on setups when I exceed Efficiency. My limit for myself is 25 yards but I regularly practice far longer and can really tell. My point for the OP is that 629 grains at 28 inch arrow is 22 gpi which is a lot for a 39 pound bow. But hey ultimately…. I hope she bags a deer and I’ll just shut my trap.
 
katiesmom said:
Gentlemen Thank-you for all your help this summer. Here's what I plan to go to the woods with, this year, anyway.

Galaxy Sage recurve at 45#@28; 39#@25 for me. D97 string. Glove
EFA 4 arrow strap on quiver.
Easton xx75 2016 gamegetters at 28 inches with 5 in left wing feathers and 100 gr insert.
Cutthroat single bevel left wing 200 gr. broadhead.
Total arrow weight: 629

Shooting 20 yards and in.

Sooooo I have 31 days and a wakeup. I know some will shake their heads and that's okay. I'm comfortable shooting this setup. We will see what happens.

Good hunting to all!!
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I just noticed this. You switched bows from original post. Any reason for it? Not one here to argue with what works and sage does fine. But your original post had a bear I believe. Had me all thrown off. Just curious here (no condemnation) why the change?
 
Petrichor said:
I just noticed this. You switched bows from original post. Any reason for it? Not one here to argue with what works and sage does fine. But your original post had a bear I believe. Had me all thrown off. Just curious here (no condemnation) why the change?
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Simply heavier draw weight. 45 on the Sage vs 40 on the Bear. Or 39 on the Sage (at my draw length) vs 34 on the Bear.

The reality is I most likely will hunt with both.
 
Well don’t let the Light-bow deter you. I typically am an advocate for light bows as they require you to perfect your form. Whereas there are some people that shoot heavier bows simply because they rip past their bad releases and mask bad form. I’m excited for you.
 
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Allegheny Tom, thanks for posting that chart. I want to highlight some things in the fine print.
Whether you prefer a light or a heavy arrow, there is some great stuff in Ashby’s work. Archers tend to debate Ashby‘s recommendation of heavy arrows and high FOC. But many ignore the other factors that he has identified. Factor 1 is structural integrity of the entire arrow and tip system. Multiple factors are about broadhead design, and there’s two or three factors related to shaft design.

12 Arrow Penetration Factors — Ashby Bowhunting Foundation

www.ashbybowhunting.org www.ashbybowhunting.org
 
Fozzie Bear said:
Allegheny Tom, thanks for posting that chart. I want to highlight some things in the fine print.
Whether you prefer a light or a heavy arrow, there is some great stuff in Ashby’s work. Archers tend to debate Ashby‘s recommendation of heavy arrows and high FOC. But many ignore the other factors that he has identified. Factor 1 is structural integrity of the entire arrow and tip system. Multiple factors are about broadhead design, and there’s two or three factors related to shaft design.

12 Arrow Penetration Factors — Ashby Bowhunting Foundation

www.ashbybowhunting.org www.ashbybowhunting.org
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X2
 
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