Question about draw weight versus arrow speed

[Almostpighunter]

Hey all.

I have what may be an obvious question for everyone; however, I really want to hear what you guys think in case my head is simply bamboozled.

I just finished a mulberry bow that came out a bit lighter in draw weight than I normally prefer (43#@28"). It was a salvage situation so any finished bow was going to be a great bow, but I really fell in love with it while it was coming together and was a bit heartbroken by the low draw weight. I went to shoot it in and was surprised to see how zippy the arrows were flying off the thing. Curiosity got the better of me and I made my way to a Chrono that clocked my medium-heavy arrows at 150fps avg. (148-152 range for 5 shots).

Interestingly, my heavier bows (50-65# @ 28") aren't really all that much faster. The 65" bow is the fastest, but only by a little bit (top speed of 158 fps).

Given all that above info, my question is this:

"Do you think the Ravens have a chance this year in the Superbowl?"

J/K  , the actual question is:

"Does the draw weight of the bow have any additional impact on the arrow's performance beyond flight speed."

I am going hunting at the end of the month and would love to take the light, short mulberry with me; however, if the arrows will have better penetration for some reason with a heavier draw weight (even though the arrow is flying at more or less the same speed) I'll take a heavier bow instead. I realize I may be asking for trouble and a lot of comments about the importance of shot placement, FOC weight in the arrow, etc... but I'm really trying to strictly look at this from the perspective of any differences in an arrow's performance when shot from 2 different draw weight bows, but otherwise traveling the same fps.

Thanks in advance! - Mike

[Del the cat]

Assuming it's the same arrow you are shooting from your hypothetical bows:-
Once the arrow has left the bow (and settled down in flight) all there is it's speed, the bow has ceased to be relevant.
So the draw weight makes no difference to the arrow's performance...but it may make a difference to your accuracy.
In Hardy's book 'longbow' there is mention of a heavy draw weight Aftrican bow (90#?) which was cut down a tad, re-tillered at a lighter draw weight and it shot faster.
Draw weight is just a rough indicator of the power/speed which is going into the arrow, a good 40# can easilly out shoot a bad 50#
Del

[johnston]

Take the Mulberry.

Lane

[Justin Snyder]

Yes the bow does have effect beyond speed. The arrows should be tuned to the bow for good flight. A 60# bow that is center shot might shoot a certain arrow well (hit the target) while a bow that is not center shot will shoot them poor (left or right of the target), or the other way around. The arrows are probably stiffer for the heavier bow and probably a little heavier. Even if the arrows fly at the same speed, the heavier arrow will penetrate deeper than the light arrow. If your arrows are have the correct spine for each of your bows and both have good arrow flight and shoot accurate, then both can be good hunting bows. You never mentioned what you are hunting. That might influence which bow would be better.

[half eye]

Hey Mike,
      If I understand your question correctly......if 2 objects of the same weight are traveling at the same speed they possess the same kinetic energy (ability to do work). That's just a fact, so if that is basically what you have goin on with your different bows then it seems to the one-eyed old guy (also vertically challenged) you will probably shoot the lighter bow more accurately over a period of time.
      Broadheads kill by exanguation, not hydraulic shock, so enough kinetic energy to allow penetration of the chest cavity will kill anything. Since all your bows are shooting basically the same speed with the same arrow there should be no difference in the end result.
      If the heavier bows are also shooting heavier arrows (but the speed is the same) then the heavier equipment will penetrate farther, because of higher driving mass.
rich

[crooketarrow]

   I'm a hunter formost so my answer is easy for me take the bow that you like and shoot the best. Its far better to hit your target but I under stand your question. If we only knew the answer to that 64 dollor question to why now and then you build a bow thats shoots faster at a lower weight than our heavyer bows we'd build alsome bows all the time. But every now and then we get a stave that this happens. One of the reasons we build bows I'd guess.

[Will H]

I agree with half Eye. What did your arrows weigh on the different bows?

[Kegan]

All an arrow gets from the bow is energy. If a bow stacks or lacks mechanical efficiency then the draw weight won't matter because the arrow will only have X speed anyway. Now if a lighter bow has a plump F/D curve and higher efficiency, it can very easily send that arrow at X fps too. It's the same arrow, same speed, same lethality. The arrow kills the critter, not the bow, so make it a good'un

[osage outlaw]

Is there a big physical weight difference between the two bows?  Maybe the heavier draw weight bow has a lot more mass in the limbs that are robbing the arrow of energy/speed.  The Mulberry bow might be more evenly matched in draw weight to limb mass. 

[Almostpighunter]

Thanks for the responses all.

Actually the same arrow was fired from the different bows. So as far as the mass of the arrow is concerned it is exactly the same. The mulberry is shooting at avg. 150fps while the heavier bows (50 & 65#) are shooting between 153-158 avg. I don't do very much hunting and am pretty much a rookie when it comes to harvesting animals (see my PA name for reference). I'm hoping to be able to drop the "Almost" from my moniker at the end of the month by taking a boar and keep hearing about other hunters wanting 70+ Lbs of draw weight for pigs, but are making no mention of arrow speed; thus, I was wondering why. Maybe some kind of a kinetic energy thing or some other reason that I was unaware.

I think it makes sense that after the arrow leaves the bow, then the bow's work is done and the rest is more dependent on the arrow specs than anything else.  I thought I'd ask just in case someone decides to look at me cross-eyed bringing a 43# bow to a pig hunt. I wouldn't blame them as I probably would have looked at them exactly the same way up to now.

Thanks to everyone again (I'm probably gonna bring both bows anyway and decide which one to use when I get there... )

[George Tsoukalas]

That is an exceptionally fast 43# bow that you have there. Enjoy it. I can't think of any reason why you would want to take a heavier bow that shoots the same. Jawge

[johnston]

Take the Mulberry .

Lane

[osage outlaw]

I was talking about the mass of the bow limbs not the arrow.

[JW_Halverson]

Take the mulberry, leave the cannoli.

[Pappy]

I am with Jawges,that is exceptional speed for 43 lbs.  Seems about right for the 50 and a little slow for the 65 .So to me there is no question ,I would take the Mulberry. No reason it won't do the job
with a good sharp head and good shoot.I have also had my trouble on them piggies.
   Pappy