However, I have wondered many times if there is a chart or a table where a person can enter their arrow mass, and their arrow speed (taken from a chronograph RIGHT in front of the bow riser) to actually determine arrow speed at 20 yards or 40 yards. Does anyone know of such a data source?
I have always wondered how much velocity is lost (and how slowly/quickly it is lost) as an arrow travels downrange......
Eagle's Link
really?
nicely done, BTW
Tilzbow's Link
Go to the website, scroll down using the menu on the left to "Balistic Calc" (it's nearly at the bottom) and that'll give you a tool that'll provide the data you're looking for. I can't vouch for the accuracy since I haven't checked it but it should be close.
I use a tool called Archery Program Pro that's pretty accurate and interactive but it's not free. It does lots more than give estimated downrange velocity and energy. I used it to print a sight tape for my Tommy Hogg that seems accurate out to 120 yards but it's damn hard to know for sure since 120 is a long ways out....
Scott
Tilzbow's Link
The thought process ended up that a mid weight arrow was great because you had speed for shooting fairly flat but also better down range energy.
That is one of the main advantages of shooting a heavy arrow, it maintains its velocity and therefore its KE. The further the shot the greater the advantage in KE.
A 350 grain arrow will lose about 12% of its kinetic energy at 40 yards, were as a 450 grain arrow will only lose about 4% - 6% of it energy at the same distance.
It's also one of the main disadvantages. The further the shot the more critical distance estimation becomes due to the rapid change in trajectory with heavy arrows.
We know that extreme fletching known as flu-flu has little impact on initial velocity but all but stops the arrow a relatively short distance out. I conclude variations in fletching will have a measurable impact on downrange speed and, therefore, trajectory.
Hopefully the difference won't be seen much then? Bowhunting is a close-range sport. I have killed two elk at 40 yards. I wish I could have been closer. In any case, I don't falt someone who can make a lethal shot at a distance farther than what I can. Even so, I wish we would worry more about our ability and less about the ability of the technology we carry.
I'm not trying to start any controversies, just advertising my thoughts.
Are you sure about that? I think you will find that the KE of the heavier/slower arrow usually starts out slightly greater than that of a lighter/faster arrow when shot from the same bow.
These arrows are figured using my Elite GT500. Other manufacturers bows will differ.
Elite GT500 - 30 inch draw, 70 lbs, 352 grain arrow, feathers
At the bow, speed = 325.9, k.e. = 83.2 20 yards - speed = 315.6, k.e. = 78.1 30 yards - speed = 310.6, k.e. = 75.6 40 yards - speed = 305.8, k.e. = 73.3 50 yards - speed = 301, k.e. = 71 60 yards - speed = 296.4, k.e. = 68.8
Elite GT500 - 30 inch draw 70 lbs, 400 grain arrow, feathers
At the bow, speed = 300.2, k.e. = 79.3 20 yards - speed = 291, k.e. = 74.5 30 yards - speed = 286.5, k.e. = 72.3 40 yards - speed = 282.1, k.e. = 70.1 50 yards - speed = 277.9, k.e. = 68 60 yards - speed = 273.8, k.e. = 66
Elite GT500 - 30 inch draw 70 lbs, 432 grain arrow, feathers
At the bow, speed = 287.8, k.e. = 79.5 20 yards - speed = 279.7, k.e. = 75.1 30 yards - speed = 275.7, k.e. = 73 40 yards - speed = 271.9, k.e. = 71 50 yards - speed = 268.2, k.e. = 69.1 60 yards - speed = 264.6, k.e. = 67.2
According to T.A.P. and my bow, the heavier arrow doesn't catch up to k.e. until 60 yards. Beyond 60, the heavier arrow wins.
I can't vouch for the heavier arrows, as I have not shot them through the chrono to prove or disprove their calculated speed, only the lightest arrow and I have only chrono'd it at the bow and 25 yards.
Purdue... I ran some different arrow weights for a comparrison. Here are the results. Now, don't shoot the messanger, I am only quoting what T.A.P. says.
These arrows are figured using my Elite GT500. Other manufacturers bows will differ.
Elite GT500 - 30 inch draw, 70 lbs, 352 grain arrow, feathers
At the bow, speed = 325.9, k.e. = 83.2
20 yards - speed = 315.6, k.e. = 78.1
30 yards - speed = 310.6, k.e. = 75.6
40 yards - speed = 305.8, k.e. = 73.3
50 yards - speed = 301, k.e. = 71
60 yards - speed = 296.4, k.e. = 68.8
Elite GT500 - 30 inch draw 70 lbs, 400 grain arrow, feathers
At the bow, speed = 300.2, k.e. = 79.3
20 yards - speed = 291, k.e. = 74.5
30 yards - speed = 286.5, k.e. = 72.3
40 yards - speed = 282.1, k.e. = 70.1
50 yards - speed = 277.9, k.e. = 68
60 yards - speed = 273.8, k.e. = 66
Elite GT500 - 30 inch draw 70 lbs, 432 grain arrow, feathers
At the bow, speed = 287.8, k.e. = 79.5
20 yards - speed = 279.7, k.e. = 75.1
30 yards - speed = 275.7, k.e. = 73
40 yards - speed = 271.9, k.e. = 71
50 yards - speed = 268.2, k.e. = 69.1
60 yards - speed = 264.6, k.e. = 67.2
According to T.A.P. and my bow, the heavier arrow doesn't catch up to k.e. until 60 yards. Beyond 60, the heavier arrow wins.
I can't vouch for the heavier arrows, as I have not shot them through the chrono to prove or disprove their calculated speed, only the lightest arrow and I have only chrono'd it at the bow and 25 yards.
Purdue... I ran some different arrow weights for a comparrison. Here are the results. Now, don't shoot the messanger, I am only quoting what T.A.P. says.
These arrows are figured using my Elite GT500. Other manufacturers bows will differ.
Elite GT500 - 30 inch draw, 70 lbs, 352 grain arrow, feathers
At the bow, speed = 325.9, k.e. = 83.2
20 yards - speed = 315.6, k.e. = 78.1
30 yards - speed = 310.6, k.e. = 75.6
40 yards - speed = 305.8, k.e. = 73.3
50 yards - speed = 301, k.e. = 71
60 yards - speed = 296.4, k.e. = 68.8
Elite GT500 - 30 inch draw 70 lbs, 400 grain arrow, feathers
At the bow, speed = 300.2, k.e. = 79.3
20 yards - speed = 291, k.e. = 74.5
30 yards - speed = 286.5, k.e. = 72.3
40 yards - speed = 282.1, k.e. = 70.1
50 yards - speed = 277.9, k.e. = 68
60 yards - speed = 273.8, k.e. = 66
Elite GT500 - 30 inch draw 70 lbs, 432 grain arrow, feathers
At the bow, speed = 287.8, k.e. = 79.5
20 yards - speed = 279.7, k.e. = 75.1
30 yards - speed = 275.7, k.e. = 73
40 yards - speed = 271.9, k.e. = 71
50 yards - speed = 268.2, k.e. = 69.1
60 yards - speed = 264.6, k.e. = 67.2
According to T.A.P. and my bow, the heavier arrow doesn't catch up to k.e. until 60 yards. Beyond 60, the heavier arrow wins.
I can't vouch for the heavier arrows, as I have not shot them through the chrono to prove or disprove their calculated speed, only the lightest arrow and I have only chrono'd it at the bow and 25 yards.
659 grains..........44.85 ft-lbs KE
584 grains..........43.80 ft-lbs KE
507 grains..........43.48 ft-lbs KE
498 grains..........44.07 ft-lbs KE
433 grains..........43.03 ft-lbs KE
347 grains..........41.95 ft-lbs KE
Given the accuracy tolerance of my chronograph, the calculated KE could vary about +/- .6 ft-lbs.
Can you offer any explanation for the KE increasing when the arrow weight dropped 11 grains (from 507 grains to 498 grains?) Chronograph variation? The +/- variation might be a little greater than .6 wouldn't it....that just matches the next lower value.......no addtional extrapolation considered?
Jake
However, the trend and the logic seems to indicate that more weight (mass) = more bow efficiency = more KE.
It is theory... most of it. As I mentioned, the 352 grain arrow was measured with a chrono. To be right honest, The 352 arrow was an arrow I used last year for 3-d and golf. I think it was vanes. The others were another arrow I used with feathers and I think I just changed the weight of the arrow to get the data. So, this may be showing vanes vrs feathers, which the feathers at longer distances will slow down much faster. I have a new light for my Pro Chrono that my wife is giving me for christmas. I can run the number again, after christmas, only this time do an actual shot through the chrono for each of the different weights. That will give a more accurate picture of what is going on. I had to change the arrow shaft on the heavier arrow to get the correct spine as when I increased the tip weight, the spine became all out of whack. That probably doesn't matter for the computer, only when actually putting an arrow through the bow.
A heavier arrow starts out with more energy and momentum, and retains it better downrange because it looses velocity at a slower rate. It looses velocity at slower rate for two reasons. First it's heavier, so it has more momentum. Also, drag varies by the square of velocity, so the faster arrow has more drag, and therefore slows faster initially than the heavier/slower one.
If the heavy arrow has more energy and retains it better, why do distance shooters (flight archery) alway shoot the lightest arrow possible that gives good flight ? Why doesn't the heavier arrow go further?
While chrono'ing different weight arrows with my Matthews LX and Bowtech Ally bows, the KE always went UP with the heavier arrows.
Energy/momentum and velocity/max range are two different things. I have to assume that they use very little fletching, so drag is not as great an issue as that required to stabilize a BH. Also, speed. This is the ONLY advantage to a light arrow. A heavier/slower arrow is in flight longer for the same distance traveled, thus the force of gravity effects it for a longer period of time. This is why a lighter arrow has a flatter trajectory and goes farther shot out of the same bow. Now if you launch the heavier arrow at the same speed as the lighter one, it WILL go farther.
At normal bow hunting ranges, speed is simply not an issue. Momentum translated into penetration potential is much more important.
That's right, very small fletching and even elliptical shaped shafts to minimize drag, but the lighter / faster arrow still has more drag due to its higher velocity, at least initially. At some distance the heavier arrow should go faster than the light arrow.
"A heavier/slower arrow is in flight longer for the same distance traveled, thus the force of gravity effects it for a longer period of time."
I see what you are saying. I just thought that the longer time of flight might also mean that it could go further especially since it is going faster for part of its flight.
I haven't actually tried this, but i would think that a heavy flu-flu arrow would go further than a light flu-flu a arrow. Weight is trumping drag as far as distance is concerned.
Evidently there is a point, as you diminish drag, where weight is no longer helpful, as flight archery demonstrates.
"Momentum translated into penetration potential is much more important."
I still can't buy that. At least it isn't always true. Have you seen these?
http://www.youtube.com/watch?v=t4RGcyZ_gJY
http://www.youtube.com/watch?v=VAfK0sBsZBw
My own tests at close range demonstrates the same. I would think that downrange results would be different.
