Hey Speed Demons, I've done the math...

[bugler]

Are you one of those archers who is constantly chasing the maximum possible speed out of your bow? Using lighter arrows and points, removing string silencers, shorter fletching, anything to squeeze a couple more feet per second from your setup? Well my friend, I aim to set you free.


I think that many archers overestimate the benefit to be gained from maxing out speed and I’ll show you why. This may get a little long winded but hopefully not difficult to follow.


Let’s look at a real life scenario. Two archers use the same model bow (at the same peak weight and draw length) to shoot at a target that is 40 yards away but they misjudge by 5 yards and make perfect 35 yard shots. Archer A launches a 385gr arrow at 290fps and B lobs a 500gr arrow at 255, a 35fps difference. The Feb 2014 issue of Bowhunting World has a bow report for the Elite Energy 32 that shows these approximate numbers.


So the question is: What is the difference in drop over that 5 yard interval between the two arrows?

http://i1082.photobucket.com/albums/j370/gterpsma/SpeedSketch_zpsce061255.jpg (http://s1082.photobucket.com/user/gterpsma/media/SpeedSketch_zpsce061255.jpg.html)

Anybody know this one? Care to take a guess?

[adriaticum]

This is not an overly complicated calculation.
http://en.wikipedia.org/wiki/Trajectory

I'm not sure how important it is what the difference is beyond the target?

[Mikey Rafiki]

^He's saying the object was actually 40 yards away but the person shot dead on assuming 35 yards

Just over 6 inches, using the most rudimentary equation I can.

I didn't particularly enjoy physics in college.

[bugler]

The point is that it doesn't matter if you are dead on with either bow. If you have the correct range both arrows will hit in the center. The question, put another way, is how much does the fast setup save your bacon if you misjudge by 5 yards. I think this is a pretty common scenario in the bowhunting world. Most people generally seem to estimate in 5 yard increments. So, here goes:

I’ve set the high point in the trajectory at half way to the target. The effect of wind resistance and the fact that arrows are generally started from below the sight line would actually push the high point closer to the target, thus decreasing the amount of time for gravity to act on it, (and therefore decreasing the difference), but this is an unknown variable so I will err on the side of the fast arrow.

The aforementioned bow report showed the speed at 20 yards. The 500gr arrow had lost 6fps while the 385gr was reduced by 14fps, more than twice the rate. The center of the gap between 18 and 40 yards would be where the arrows are travelling at the approximate average speed over that interval. At 9 yards past 20 I think it is fair to say the fast arrow would lose another 6 and we’ll take 3 off of the slow one, so I’ll use 270fps for the light arrow and 246 for the heavy one

[bugler]

We need to know how much time that gravity will be acting on the arrow.


Time=Distance/Speed Remember, the arrow only starts downward when it is ½ way to 35 yards.


A) For 35 yards T=52.5ft/270fps=0.19444s For 40 yards T=67.5ft/270fps=0.25s


B) For 35 yards T=52.5ft/246fps=0.21341s For 40 yards T=67.5ft/246fps=0.27439s


Now we need to know the vertical speed of the arrow as it passes through that last 5 yards.


Vertical Speed=GravityxTime


A) At 35 yards V=-32.174fps sq x 0.19444s=-6.256fps At 40 yards V=-32.174 x 0.25=-8.044fps Average vertical speed through that interval = -7.15fps


B) At 35 yards V=-32.174fps sq x 0.21341s=-6.866fps At 40 yards V=-32.174 x 0.27439=-8.828fps Average vertical speed through that interval = -7.847fps


So you can see that the slower arrow drops at a faster rate simply because gravity has more time to act on it. But how much difference does it make over that 5 yard interval?

[bugler]

First we need to know the time it takes to cover that 5 yards.


A) T=15ft/270fps=0.05556s B) T=15ft/246fps=.061s


So the amount that each arrow drops below the sight line between the 35 and 40 yard mark is:


Distance=Speed x Time


A) D= -7.15fps x .05556s = -0.3973ft, converted to inches = -4.767
B) D= -7.847fps x .061s = -0.4787ft, converted to inches = -5.744


The difference is just a hair under 1 inch. Keep in mind that wherever there was a small unknown variable to the calc’s I erred on the side of the light arrow, so the difference would actually be a little less than this.


That is well inside most shooters’ group size at 40 yards.

[bugler]

Incidentally, using the same scenario I worked out the distance at which each arrow would fall outside of a 4 inch radius circle (generally considered the margin for error on a deer size target):

For A it is 12.58ft past 35 yards, for B it is 10.45ft, so the guy with the speedy arrow can misjudge the range by an extra couple of feet .

[adriaticum]

Naturally, heavier (slower) arrow will drop faster.
I think your question relates to bullets in the same way.
Energy at the target is really important, everything else is variable and can be adjusted.
Product of weight, initial force and distance.
With the slower arrow you can adjust the angle to reach the target further out but the heavier arrow will have more force when it hits the target than a lighter (faster) arrow.

But will the lighter arrow have enough energy at the target to kill?

[bugler]

I put this out there because many archers get sucked in to the speed game. To get faster arrows they sacrifice momentum (ability to penetrate), more problems with planing using fixed blade broadheads so they switch to mechanicals, more noise at the shot, etc. but in reality the gain is fairly minimal, and probably much less than expected. Whether it is worth all that to gain an inch is a matter of your own opinion.

[adriaticum]

At least in archery it's simple.
If you want more speed out of your bow, go to the gym.
:mrgreen:

[Clint_S]

Naturally, heavier (slower) arrow will drop faster.

Not true. Gravity pulls at the same rate regardless if it's a 500 grain arrow or a 500lb cannonball.

[hunter1993ap]

Not true. Gravity pulls at the same rate regardless if it's a 500 grain arrow or a 500lb cannonball.

part is true, because it takes longer to reach the target it drops more.

[mikeboehm]

I figured it out. If u want more speed buy the PSE Full throttle

[adriaticum]

Slower arrow assumes that its heavier. And heavier arrows will always drop faster.
Sure, aerodynamics will play a role in the rate of drop too.

[Fred1]

Lob vs flat... whap vs zip... penetration is still key. Correct!? ;)

[adriaticum]

Not true. Gravity pulls at the same rate regardless if it's a 500 grain arrow or a 500lb cannonball.

You are talking aerodynamics.
If objects are the same weight the one with better aerodynamics will go further.

[hunter1993ap]

You are talking aerodynamics.
If objects are the same weight the one with better aerodynamics will go further.

ya but if you brought a 500gr arrow to the top of a tressel and a 1000 gr arrow and dropped them at the same time they would hit the ground at the exact same time.

[bugler]

Air resistance does play a role in the horizontal component, that is why the fast arrow slows down at a faster rate than the slower arrow. But the vertical speeds are so low and similar to each other that the effect of air resistance would be negligible.

[bugler]

Lob vs flat... whap vs zip... penetration is still key. Correct!? ;)

To me accuracy is very important, but speed doesn't really improve accuracy very much. In my opinion the improvement in accuracy is not worth reducing your penetrating power by 25% or shooting a noisier bow, and definitely not worth resorting to mechanical broadheads to get field point accuracy.

[Ambush]

And the heavy arrow will retain it's momentum at a longer range, which means penetration on game.

It is my opinion that the need [lust] for speed is the cause of far more misses than an arrow traveling 30 fps slower.

[Brez]

Lob vs flat... whap vs zip... penetration is still key. Correct!? ;)
I think you nailed it. The advantage of a flatter shooting set-up is more fudge-factor when estimating distance. The heavier, slower set-ups, in my opinion, are more forgiving for shooting.....especially for us fingershooters.

[Foxtail]

Speed is what sells. Almost every bowmaker out there has their speed bow as their flagship bow. And there is nothing wrong with that. Speed does help and the faster the bow the better. A heavier arrow is also better but with the speed of today's bows a heavy arrow and a light arrow are going to pass through almost any animal with a good coc broadhead. Say you have a bow with an IBO of 300 fps shooting a 500 gr arrow around 235 and then a 350 fps IBO bow shooting the same arrow 285 fps. Which would you rather have? This is why companies make the speed bows and why people want them.

[E.V.B.H.]

It's not really about speed all the time. Just because you shoot a fast bow doesn't mean you are shooting a light arrow. A faster bow with a heavy arrow makes high ke and will bust through bone and tough tissue much better. A fast bow=a powerful bow and allows for heavy arrows and still have a reasonable trajectory. The way I see it is the faster your bow the heavier arrow you can shoot. I personally think a lot of people shoot to light an arrow for hunting. Heavier is more accurate and bucks the wind much better as well.

[firstlight]

I opt for arrow penetration over speed.

It may sound good to get your arrow to the animal faster but if you poll most archers it's really about a well placed shot and penetration.

For the average kill shot distance, getting there .25 seconds earlier than a well tuned bow and arrow combo with a heavy enough (and quiet) arrow will very rarely make any difference for harvesting a game animal.

[bugler]

Speed is what sells. Almost every bowmaker out there has their speed bow as their flagship bow. And there is nothing wrong with that. Speed does help and the faster the bow the better. A heavier arrow is also better but with the speed of today's bows a heavy arrow and a light arrow are going to pass through almost any animal with a good coc broadhead. Say you have a bow with an IBO of 300 fps shooting a 500 gr arrow around 235 and then a 350 fps IBO bow shooting the same arrow 285 fps. Which would you rather have? This is why companies make the speed bows and why people want them.

Agreed, the more efficient (ie faster) your bow the more speed any given arrow will receive from it. But I also know that many people who buy the speed bow are not happy unless the chrony tells them their arrows are meeting the advertised speed, so they will do all they can to get the speed up as high as possible. This is where I think too much emphasis is placed on speed.

[donny.brooke]

Im a big believer in your bow being quiet. No deer ever jumped the string on a bow it couldnt hear but has many times on a pse omen shooting 360 fps.

[Xenomorph]

I opt for arrow penetration over speed.

It may sound good to get your arrow to the animal faster but if you poll most archers it's really about a well placed shot and penetration.

For the average kill shot distance, getting there .25 seconds earlier than a well tuned bow and arrow combo with a heavy enough (and quiet) arrow will very rarely make any difference for harvesting a game animal.

Some people treat their bows like their '70 Chargers, others just enjoy the extra OOMPH for the boost in KE. I don't go looking for speed, I like smooth, solid wall and quiet shot. If that whips the 500grain arrow around or over the 300fps by all means, thank you.



Agreed, the more efficient (ie faster) your bow the more speed any given arrow will receive from it. But I also know that many people who buy the speed bow are not happy unless the chrony tells them their arrows are meeting the advertised speed, so they will do all they can to get the speed up as high as possible. This is where I think too much emphasis is placed on speed.

I bought a chrono to figure out the end result of my arrow build. Don't have the numbers yet but I should, if all theoretical numbers prove correct, I'll be shooting some real meat getting bolts with an end KE around 100+

No, I did not choose the Hoyt for the speed, I chose if for how light, smooth to draw and quiet shot it has.


Im a big believer in your bow being quiet. No deer ever jumped the string on a bow it couldnt hear but has many times on a pse omen shooting 360 fps.

Main reason why I passed on the Omen. Super aggressive useless cycle. I don't need something shooting at almost 400fps if that means it's going to zap my armguard no matter what I do and make more noise than grandma passing wind.