dissapointed with my arrow weight
04-11-2005, 01:27 PM
#12
Join Date: Mar 2004
Location:
Posts: 150
RE: dissapointed with my arrow weight
The weed eater string is a great idea. I have always thought about trying drinking straws to do the same thing. We have a minimum arrow weight law, and instead of leaving the arrows long, I was thinking of adding weight to a carbon to make it legal.
All it takes is a good scale.
All it takes is a good scale.
04-11-2005, 10:18 PM
#13
Join Date: Mar 2005
Location:
Posts: 67
RE: dissapointed with my arrow weight
a direct take from hunters friend best info I've found Sorry it's so long I don't know how to put in a URL
__________________________________________________ ____________________
Kinetic Energy: Arrow Mass & Arrow Velocity
How much penetration, or knock-down power, your arrows will have is a matter of kinetic energy. Arrows which impact the target with more kinetic energy will penetrate the target more deeply than arrows with less kinetic energy. Kinetic energy is the energy of motion. Any object which has motion has kinetic energy. Total kinetic energy depends upon two variables: the mass of the object and the speed of the object. This is more an issue of arrow selection than bow selection, but an important issue nonetheless - and another of those "trade-offs" to consider. A bow is generally more efficient, and somewhat quieter, when launching a heavier arrow. But since lightweight carbon arrows are all the rage, we decided to conduct a test to see if the extra speed was really paying off for hunters.
Kinetic Energy - Our Test
Kinetic energy of an arrow can be found by using the formula KE=(mv²)/450,240 where m is the mass of the arrow in grains and v is the velocity of the arrow in fps. So a bow that's capable of launching a 350 grain arrow at 290 fps, sends the arrow with (350x290x290)/450,240 or 65.38 foot-pounds of Kinetic Energy. Using our Competition Electronics chronograph, our digital grain scale, and a Bowtech Patriot set for 28" draw length and 60# draw weight (representing an average shooter's settings), we decided to put the issue of arrow speed vs. kinetic energy to the test.
We prepared 9 arrows, ranging from 250 grains up to 650 grains in precisely 50 grain increments. Each arrow was fired from our test bow, through the chronograph and the results were recorded (table below). Five trials were conducted for each arrow - to achieve a reliable speed measurement (average). Each arrow was fired from the same distance, from the same shooter, and without any modifications to the bow's settings during the test. The test was conducted at our indoor range, where lighting and environmental conditions could be held constant throughout our test.
Our Test Results - Chronograph (speed) Test
FPS
Trail 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
250G Arrow 294 294 295 294 294 294.2 FPS
300G Arrow 274 272 273 273 273 273.0 FPS
350G Arrow 256 256 257 255 256 256.0 FPS
400G Arrow 242 242 242 243 242 242.2 FPS
450G Arrow 231 231 231 230 231 230.8 FPS
500G Arrow 220 219 220 220 219 219.6 FPS
550G Arrow 211 210 209 210 209 209.8 FPS
600G Arrow 202 201 201 202 202 201.6 FPS
650G Arrow 196 195 195 195 194 195.0 FPS
Clearly we can see that lighter arrows indeed fly considerably faster. So where's the trade-off? Faster is better right? In most cases yes. But if you're concerned about Kinetic Energy or knock-down power, a heavier arrow may provide a little more penetration. Is the loss in speed worth the added kinetic energy? You decide. Look at the same chart - converted into kinetic energy (ft-pounds) instead of feet-per-second.
Kinetic Energy Developed by Arrow Weight
FT-POUNDS
Trail 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
250G Arrow 47.99 47.99 48.32 47.99 47.99 48.06 ft-lbs
300G Arrow 50.02 49.30 49.66 49.66 49.66 49.66 ft-lbs
350G Arrow 50.95 50.95 51.34 50.55 50.95 50.95 ft-lbs
400G Arrow 52.03 52.03 52.03 52.46 52.03 52.12 ft.lbs
450G Arrow 53.33 53.33 53.33 52.87 53.33 53.24 ft-lbs
500G Arrow 53.75 53.26 53.75 53.75 53.26 53.55 ft-lbs
550G Arrow 54.39 53.87 53.36 53.87 53.36 53.77 ft-lbs
600G Arrow 54.38 53.84 53.84 54.38 54.38 54.16 ft-lbs
650G Arrow 55.46 54.90 54.90 54.90 54.33 54.90 ft-lbs
As you can see, the gains in KE are relatively minor. To gain a few more ft-pounds of KE, you'll have to sacrifice a considerable amount of arrow velocity. Of course, every bow will not perform exactly as our test bow did. However, you can expect similar gains and losses in performance with most modern compound bow models. Consider the trade-offs carefully.
Performance Summary: Doubling Your Arrow's Mass
300g Arrow (5 g/p/p) 273.0 fps 49.66 ft-lbs of KE
600g Arrow (10 g/p/p) 201.6 fps 54.16 ft-lbs of KE
LOSS of Velocity: 26.2% GAINS in KE: 8.3%
And while some archers stubbornly stick by their hefty "big-game" log style arrows, an increasing number of archers are discovering that lightweight arrows can be just as effective for hunting large game - perhaps even more effective. And it should be noted that a properly placed arrow - impacting with 49.66 ft-lbs of KE would easily generate a clean pass-thru on a Whitetail Deer or Elk. So with respect to kinetic energy and big-game hunting, the practical difference between an arrow generating 49.66 ft-lbs and another generating 54.16 ft-lbs - would really be how far the arrow sticks in the dirt after passing through the animal.
From a standpoint of accuracy, you may find that lightweight arrows will yield some surprising benefits too. From the moment your arrow is released from the bow, it begins to lose trajectory. As it succumbs to the effects of gravity and air resistance, it's flight path (trajectory) changes and the arrow eventually begins to drop back to earth. Arrows which fly more quickly hold their trajectory better than slower arrows. So archers who shoot lighter-faster arrows will have less need to adjust for distance - since the faster arrows will hold a "flatter" trajectory within a given distance. In effect, the faster arrow allows you to make more mistakes in yardage estimation. If you mis-estimate a deer to be 25 yards away, and it is actually 30 yards away, a fast arrow still hits it's mark (though it might land just a little bit low), while the slower arrow misses more dramatically. Look at the trajectory chart on the right from our Bowtech Patriot experiment. The heavier arrows nosedive much more quickly than the lighter faster arrows.
With the wide variety of lightweight arrow materials now readily available, you don't have to let your compound bow lazily cough-out arrows anymore. We recommend you take advantage of the high-speed output of your new compound bow - and "lighten-up" when selecting your arrows. You'll be more accurate - and yet you'll still having more than enough KE to harvest big game animals. So put those logs away.
__________________________________________________ ____________________
Kinetic Energy: Arrow Mass & Arrow Velocity
How much penetration, or knock-down power, your arrows will have is a matter of kinetic energy. Arrows which impact the target with more kinetic energy will penetrate the target more deeply than arrows with less kinetic energy. Kinetic energy is the energy of motion. Any object which has motion has kinetic energy. Total kinetic energy depends upon two variables: the mass of the object and the speed of the object. This is more an issue of arrow selection than bow selection, but an important issue nonetheless - and another of those "trade-offs" to consider. A bow is generally more efficient, and somewhat quieter, when launching a heavier arrow. But since lightweight carbon arrows are all the rage, we decided to conduct a test to see if the extra speed was really paying off for hunters.
Kinetic Energy - Our Test
Kinetic energy of an arrow can be found by using the formula KE=(mv²)/450,240 where m is the mass of the arrow in grains and v is the velocity of the arrow in fps. So a bow that's capable of launching a 350 grain arrow at 290 fps, sends the arrow with (350x290x290)/450,240 or 65.38 foot-pounds of Kinetic Energy. Using our Competition Electronics chronograph, our digital grain scale, and a Bowtech Patriot set for 28" draw length and 60# draw weight (representing an average shooter's settings), we decided to put the issue of arrow speed vs. kinetic energy to the test.
We prepared 9 arrows, ranging from 250 grains up to 650 grains in precisely 50 grain increments. Each arrow was fired from our test bow, through the chronograph and the results were recorded (table below). Five trials were conducted for each arrow - to achieve a reliable speed measurement (average). Each arrow was fired from the same distance, from the same shooter, and without any modifications to the bow's settings during the test. The test was conducted at our indoor range, where lighting and environmental conditions could be held constant throughout our test.
Our Test Results - Chronograph (speed) Test
FPS
Trail 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
250G Arrow 294 294 295 294 294 294.2 FPS
300G Arrow 274 272 273 273 273 273.0 FPS
350G Arrow 256 256 257 255 256 256.0 FPS
400G Arrow 242 242 242 243 242 242.2 FPS
450G Arrow 231 231 231 230 231 230.8 FPS
500G Arrow 220 219 220 220 219 219.6 FPS
550G Arrow 211 210 209 210 209 209.8 FPS
600G Arrow 202 201 201 202 202 201.6 FPS
650G Arrow 196 195 195 195 194 195.0 FPS
Clearly we can see that lighter arrows indeed fly considerably faster. So where's the trade-off? Faster is better right? In most cases yes. But if you're concerned about Kinetic Energy or knock-down power, a heavier arrow may provide a little more penetration. Is the loss in speed worth the added kinetic energy? You decide. Look at the same chart - converted into kinetic energy (ft-pounds) instead of feet-per-second.
Kinetic Energy Developed by Arrow Weight
FT-POUNDS
Trail 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
250G Arrow 47.99 47.99 48.32 47.99 47.99 48.06 ft-lbs
300G Arrow 50.02 49.30 49.66 49.66 49.66 49.66 ft-lbs
350G Arrow 50.95 50.95 51.34 50.55 50.95 50.95 ft-lbs
400G Arrow 52.03 52.03 52.03 52.46 52.03 52.12 ft.lbs
450G Arrow 53.33 53.33 53.33 52.87 53.33 53.24 ft-lbs
500G Arrow 53.75 53.26 53.75 53.75 53.26 53.55 ft-lbs
550G Arrow 54.39 53.87 53.36 53.87 53.36 53.77 ft-lbs
600G Arrow 54.38 53.84 53.84 54.38 54.38 54.16 ft-lbs
650G Arrow 55.46 54.90 54.90 54.90 54.33 54.90 ft-lbs
As you can see, the gains in KE are relatively minor. To gain a few more ft-pounds of KE, you'll have to sacrifice a considerable amount of arrow velocity. Of course, every bow will not perform exactly as our test bow did. However, you can expect similar gains and losses in performance with most modern compound bow models. Consider the trade-offs carefully.
Performance Summary: Doubling Your Arrow's Mass
300g Arrow (5 g/p/p) 273.0 fps 49.66 ft-lbs of KE
600g Arrow (10 g/p/p) 201.6 fps 54.16 ft-lbs of KE
LOSS of Velocity: 26.2% GAINS in KE: 8.3%
And while some archers stubbornly stick by their hefty "big-game" log style arrows, an increasing number of archers are discovering that lightweight arrows can be just as effective for hunting large game - perhaps even more effective. And it should be noted that a properly placed arrow - impacting with 49.66 ft-lbs of KE would easily generate a clean pass-thru on a Whitetail Deer or Elk. So with respect to kinetic energy and big-game hunting, the practical difference between an arrow generating 49.66 ft-lbs and another generating 54.16 ft-lbs - would really be how far the arrow sticks in the dirt after passing through the animal.
From a standpoint of accuracy, you may find that lightweight arrows will yield some surprising benefits too. From the moment your arrow is released from the bow, it begins to lose trajectory. As it succumbs to the effects of gravity and air resistance, it's flight path (trajectory) changes and the arrow eventually begins to drop back to earth. Arrows which fly more quickly hold their trajectory better than slower arrows. So archers who shoot lighter-faster arrows will have less need to adjust for distance - since the faster arrows will hold a "flatter" trajectory within a given distance. In effect, the faster arrow allows you to make more mistakes in yardage estimation. If you mis-estimate a deer to be 25 yards away, and it is actually 30 yards away, a fast arrow still hits it's mark (though it might land just a little bit low), while the slower arrow misses more dramatically. Look at the trajectory chart on the right from our Bowtech Patriot experiment. The heavier arrows nosedive much more quickly than the lighter faster arrows.
With the wide variety of lightweight arrow materials now readily available, you don't have to let your compound bow lazily cough-out arrows anymore. We recommend you take advantage of the high-speed output of your new compound bow - and "lighten-up" when selecting your arrows. You'll be more accurate - and yet you'll still having more than enough KE to harvest big game animals. So put those logs away.
04-12-2005, 09:43 AM
#14
Join Date: Sep 2003
Location: Maine
Posts: 3,555
RE: dissapointed with my arrow weight
Mainehunt,
I'm shooting virtually the same set up as you. 74lbs 30" draw 29.75" 7595 shafts and I am shooting a 125g head. I think if you tune the bow to a 125g head you should see little diffrence in arrow flight. You'll loose a bit of speed and your tradjectory won't be quite as flat but I'm cartain the 125 g head will be the best fit for your set up. There's only one way to be certain though. Buy some 125g field points and give then a try. I think you're likely to find that a 125g head will fit your set up just as you'd want them to.
I'm shooting virtually the same set up as you. 74lbs 30" draw 29.75" 7595 shafts and I am shooting a 125g head. I think if you tune the bow to a 125g head you should see little diffrence in arrow flight. You'll loose a bit of speed and your tradjectory won't be quite as flat but I'm cartain the 125 g head will be the best fit for your set up. There's only one way to be certain though. Buy some 125g field points and give then a try. I think you're likely to find that a 125g head will fit your set up just as you'd want them to.
04-12-2005, 11:16 PM
#15
Join Date: Feb 2003
Location: Oakland Md. USA
Posts: 337
RE: dissapointed with my arrow weight
Does anyone know if the Carbon Express weight tubes will fit inside the Goldtip shafts?
Am shooting the 55/75's for 3-D and just bought a dozen pro 75/95's to hunt with.
With 125 gr. tips and 4" inch fletch they weigh in at 434 grains. Would like to get
my arrow weight up around 480 grains for more momentum down range for deer
and elk hunting. -Thanks.
Am shooting the 55/75's for 3-D and just bought a dozen pro 75/95's to hunt with.
With 125 gr. tips and 4" inch fletch they weigh in at 434 grains. Would like to get
my arrow weight up around 480 grains for more momentum down range for deer
and elk hunting. -Thanks.
04-13-2005, 05:21 AM
#16
Boone & Crockett
Join Date: Feb 2003
Location: Lehigh County PA USA
Posts: 12,157
RE: dissapointed with my arrow weight
At a 70 pound draw weight and a 30 inch draw length I would personally consider them a little bit on the light side for my tastes but I do not believe they would be unsafe to shoot. Many times we find an arrow that shoots very well out of our setups only to find that it is a bit lighter than expected. Ultimately safety and accuracy should be your primary concerns. Both criteria seem to be fulfilled with your choice of arrows and setup.
04-13-2005, 09:33 AM
#17
Join Date: Sep 2003
Location: Maine
Posts: 3,555
RE: dissapointed with my arrow weight
dsheally,
Goldtip sells their own weight tubes. http://www.goldtip.com/products/fami...&rnd=135081163
Goldtip sells their own weight tubes. http://www.goldtip.com/products/fami...&rnd=135081163
04-13-2005, 05:09 PM
#18
Nontypical Buck
Join Date: Feb 2003
Location: Central PA
Posts: 2,299
RE: dissapointed with my arrow weight
With you particular setup, 390 is an ideal setup IMO. I have shot deer shooting much less draw length and weight and heavier arrows out to 40 yards with complete pass throughs. I wouldn't worry too much. You already answered yourself, you shoot it well and have a lot of confidence in it. So whats the problem?
I think we are getting WAY to wrapped up in KE and arrow weight. If you recall, Fred Bear killed many animals all over north america with a 45 pound recurve and ceder arrows. Do you think for a minute that his bows were producing any where near the KE we are now?
I think we are getting WAY to wrapped up in KE and arrow weight. If you recall, Fred Bear killed many animals all over north america with a 45 pound recurve and ceder arrows. Do you think for a minute that his bows were producing any where near the KE we are now?
