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Technical Bow Questions - 2 different - Close shot penetration & "brace height"

Sligh1

Sligh1

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Hey, so, I'm a "deer guy" and by far not a "gear guy" when it comes to "techy stuff". Lemme ask you guys who really understand bows & maybe the 1st one "physics" some technical questions....

1) I've bowhunted for 23 years now, shot a lot of deer with my bow. One thing I've possibly noticed... Seeing if any truth to this or if this is in my head..... I have shot deer from 2 to 35 yards. (yes, I said 2 yards & that was when I was 14 & got my 1st buck on the ground) - 35 is maybe the furthest (long list of reasons, I just don't like what deer can do reaction-wise past that).... ANYWAYS.... When I shoot a deer at really close range (angle is good, no problem there), say 5-7 yards, I mean CLOSE.... Seems like my penetration is LESS than say, 20 yards. Why would this be or could this be possible? Or is this in my head & no merit? In my theory of physics, if I'm even possibly right (which maybe I'm not), momentum or something is possibly not peaked out by this period or something?
BASICALLY, BOTTOM LINE.... based on physics (of shooting/releasing arrow/energy): momentum, KE, or FOC - is there something to an arrow being allowed to reach some peak "phase" after XYZ distance where as it may be hindered at extremely close ranges? See what I'm saying?

2) Brace height. So, 5-7". Obviously, simply, longer brace height - we all understanding "more forgiving", easier to shoot, etc, etc. BUT- longer generally translates to slower IBO speeds (generally speaking when you compare almost any bow line - nothing insanely drastic but maybe 7-10 fps per inch for example). Obviously with SHORTER brace height, the upside there is higher speeds & a few other things..... Clear Ups and downs to both and obviously there gets to be a limit to how long a brace height can go (some guys say, "dude, don't go to 5", stay 6 or higher for EXAMPLE).... SO... "BOW FORGIVENESS" being important to a shooter, totally get it. Let me ask you guys this..... If a guy like me is shooting no further than 30, maybe 35 yards - would any of you consider that a case where "forgiveness" is not as important? Like, does the guy shooting 65 yard shots need "forgiveness" on bow more than short range guys? Or is it still something that is drastically impacting a guy like me? BASICALLY, BOTTOM LINE: Where or who will be impacted by Brace Height the most or in what situation? Or is there any situation where Brace height will be not nearly as relevant?

Mucho Gracias Gear Dudes!!!! ;)
 
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I am no expert. I shoot a 5" brace, not necessarily because I wanted but because I got a good deal I have learned a few things going from a 7 to a 5. I am sure I will ramble some as I can be a scatter brain. I am at 295fps and 94#KE with my setup. It shoots flat out from 0-30 then a big gap to 40 then pretty even for 5 yd increments. I to have never shot a deer at long range, I believe 20 yds is the farthest. I am 29" draw Shooting 70# with an arrow just over 500g with alot FOC. This hits like a hammer. I love a 5 now, and I think it's as forgiving as my 7. Form is very important and torque shows itself very easily. Hand grip/torque is key, consistent grip. I found the stiffer spine shoots better. I had to get new arrows and boy it made a difference.I can't comment on where the most ke is generated, but I would guess it's even from 5-30 then goes down maybe? Shooting a 5 is not for everyone, it takes practice, but I love it. I am big on KE and don't care much about speed. I also believe not all bows are equal and picking the right one/brand is also key.
 
I have no clue on the brace height. Both of my bows have been 7" and 7.25". I really think I'd struggle going less.


As far as you first question, keep in mind that momentum is what keeps an arrow moving after impact, kinetic energy basically says how hard its going to hit at impact. Both kinetic energy and momentum are direct functions of mass and velocity. Meaning as the mass and or velocity goes up, so does the energy and momentum. As SOON as that arrow leaves you bow string it is decelerating. The highest kinetic energy and momentum your arrow will see is the very moment it leaves the string after that it declines. This clearly doesn't explain your experience of less penetration at closer ranges. The only thing I can think of that would maybe play a factor is the flex of the arrow? If you've ever watched a slow motion video of an arrow leaving a bow it's amazing how much it bends. Could that possibly be the cause of what you are seeing? When you shoot a close deer, the arrow hasn't yet stabilized and is losing some momentum when it hits the deer due to not being as aerodynamic? Think pushing a straight arrow into a target vs. Pushing a slightly bent arrow into a target. More friction from the bent arrow (non-stabilized flying arrow) will quickly slow it down and cause it to lose momentum. That's the only thing that I can think of that would make the difference you are seeing. However, I wouldn't think it would be enough to notice. But there's a heck of a lot happening with an arrow flying that fast, so who knows.
 
LYON said:
I have no clue on the brace height. Both of my bows have been 7" and 7.25". I really think I'd struggle going less.


As far as you first question, keep in mind that momentum is what keeps an arrow moving after impact, kinetic energy basically says how hard its going to hit at impact. Both kinetic energy and momentum are direct functions of mass and velocity. Meaning as the mass and or velocity goes up, so does the energy and momentum. As SOON as that arrow leaves you bow string it is decelerating. The highest kinetic energy and momentum your arrow will see is the very moment it leaves the string after that it declines. This clearly doesn't explain your experience of less penetration at closer ranges. The only thing I can think of that would maybe play a factor is the flex of the arrow? If you've ever watched a slow motion video of an arrow leaving a bow it's amazing how much it bends. Could that possibly be the cause of what you are seeing? When you shoot a close deer, the arrow hasn't yet stabilized and is losing some momentum when it hits the deer due to not being as aerodynamic? Think pushing a straight arrow into a target vs. Pushing a slightly bent arrow into a target. More friction from the bent arrow (non-stabilized flying arrow) will quickly slow it down and cause it to lose momentum. That's the only thing that I can think of that would make the difference you are seeing. However, I wouldn't think it would be enough to notice. But there's a heck of a lot happening with an arrow flying that fast, so who knows.
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This was exactly how I was going to respond to #1. No scientific data, just where my head was at. It "makes sense" that the arrow hasn't yet stabilized and isn't flying "true" at ultra close distance. All the energy isn't going in the same direction. Good post.
 
Truly don't know buy asking...if you tune at point blank...5 paces...10 or whatever, are you not flying true out the gate? Maybe this just means you're quicker to complete stabilization when property tuned? A bit outside my league
 
arm said:
Truly don't know buy asking...if you tune at point blank...5 paces...10 or whatever, are you not flying true out the gate? Maybe this just means you're quicker to complete stabilization when property tuned? A bit outside my league
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Wanna make your head spin... start watching videos on Dynamic Spline. Ya.... out of my league too!
 
If you are talking about close treestands shots, it could be the deer rib causing less penetration. The ribs are thicker closer to the spine - which is where you would be hitting on a very close shot. From the ground - I have no idea. The "still bending" theory is as good as any I can think of. Those slow motion videos of the arrow leaving the bow are crazy. Makes me wonder how they can be so accurate when you see all that happening as it leaves the bow.
 
Thx guys!!! I think U r correct on the arrow needing time to straighten and stabilize. I recall those slow motion vids. I think that’s it.

Any more on brace height thoughts for a shorter range hunter appreciated. Thx again
 
Bow forgiveness is kind of a myth in my opinion on bows these days. The only thing I believe that has merit is that it is easier to hit your arm with the string on a shorter brace height bow. Think about a bow with less brace height, it is a "speed bow" most generally with very harsh draw cycles. I think many of the forgiveness discussions are triggered more by cam design than actual difference between brace height. The fact is that a shorter brace height bow, keeps the arrow attached to the string longer until the nock separates from the arrow, and thus requires a steadier bow hand through the shot. However, much of that is mitigated with today's drop away arrow rests. I doubt you could really shoot both bows and come up with a reasonable conclusion one way or the other with a drop away arrow rest. A whisker biscuit on the other hand, that might change things a little, but regardless, even a short BH bow is faster, so that also means the arrows come off the string a little faster as well.

Bottom line, I wouldn't get too excited about brace height. You would get more "forgiveness" through steadiness of a longer ATA bow, like switching from a 30 ATA bow to a 34 ATA etc...

For further reading, there are a few good articles out there by some knowledgeable folks.


https://www.fieldandstream.com/blog...brace-height-really-affect-forgiveness#page-2
 
My Halon5 is the smoothest, quietest bow I have ever shot. Rock solid back wall, no creep at all. I am beyond impressed. If I go new again I will definitely look at a 5 again.
 
My gut tells me the angles at the short distance are what make you think you are getting less penetration. At 2-5 yds you are likely very steep and thus passing thru more of the animal than at 20 when you are likely passing thru directly broadside.

Other than that it is impossible that you would get less penetration at that distance as your speed and KE are peaked and unless your tune is horrible I cannot imagine the arrow not being true at this point.

I have also been told that BH doesn’t matter under 40yds. Not sure if that is true statement or not but I really don’t see the need to sacrifice with most bows even at shorter draw lengths packing some significant punch. I really have never seen the need to shoot 350fps when my first bow at 52lbs and decent KE would put an arrow in the ground after blowing thru a deer JMO
 
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