This part of the article is going to deal with the real world numbers when a light arrow is shot vs. a heavier arrow and the speeds measured at different distances. By measuring the speed of different arrows at various distances, it is easy to calculate which arrow maintains more of its speed and thus its kinetic energy and momentum further downrange.
For the full article, please visit:
Heavy vs. Light Arrows: Downrange Speed and Power
Introduction and archery equipment for testing
Test equipment for this round of shooting
If you care about all of the math and the theory behind how arrows decelerate after leaving the bow, please make sure to read all of the original article first. For this testing, I’ll be using two arrows that are virtually identical to each other on the outside, but one will be weighted with an extra shaft and weight layered on the inside.
These first numbers come from using two Victory VForce HV arrows, one standard that weighs in at 326 grains, the other layered with a 1516 aluminum shaft on the inside that weighs 580 grains. The heavier arrow also has additional weight on the inside near the point in order to keep the FOC of both of the arrows nearly identical. Both arrow use FOBs for the fletchings.
All arrows were shot from my Elite Envy set at 29″ and 60.2 lbs. and were chronographed with and Easton Pro Chronograph.
For this testing, I shot seven shots with each arrow at point blank range, 10 yards and 20 yards; then I threw out the highest and the lowest speed, leaving five speeds to be averaged for the results. All of the speeds in each set were within +/- 0.4 fps.
Results of arrow speed testing
| Speed (fps) | KE | Momentum | Change from 0 Yards | |||
| 326 Grains | 0 Yards | 316.4 | 72.3 | 0.457 | KE | Momentum |
| 10 Yards | 308.6 | 68.8 | 0.446 | 4.85% | 2.45% | |
| 20 Yards | 299.2 | 64.7 | 0.432 | 10.55% | 5.42% | |
| 580 Grains | 0 Yards | 243.1 | 76.0 | 0.626 | KE | Momentum |
| 10 Yards | 239.6 | 73.9 | 0.617 | 2.81% | 1.42% | |
| 20 Yards | 235.3 | 71.3 | 0.606 | 6.27% | 3.18% | |
The actual testing results follow what would be expected from the theory and math discussed earlier. I would like to test the speeds out to further distances and will do so in the future to get a better picture of behavior downrange.
It’s interesting to see just how much more the lighter arrow slows down and sheds its kinetic energy and momentum. The lighter arrow is losing speed at a rate 40-45% faster than the heavier arrow. At point blank range, the heavier arrow starts with 3.7 ft-lbs. of KE more than the light, and by only 20 yards it had 6.6 ft-lbs. more KE. I would say that is a significant difference!
Of course the extra KE and momentum come at a cost, trajectory. The heavier arrow is going to drop significantly more at every distance and yardage estimation becomes much more critical. A three to five yard mis-judgement in yardage with the lighter arrow could still result in a clean kill shot on an animal, while with the heavier arrow it most likely would result in a much poorer shot or even perhaps a complete miss.
That being said, having a fast arrow is no substitute for practice in yardage estimation or using a range finder when possible. Each archer needs to know their own equipment and make their own decisions on arrow weight depending on the game being hunted and where they are hunting. Know your equipment and practice with it constantly!
Future testing
In the future I plan on doing testing out to forty or more yards, and also with some lighter and heavier arrows. I have some 262 grain Speed Pro Max arrows donated to the cause that should be fun to play with (yes, I will be shooting them at 60 lbs, not recommended!) I will also use some different types of fletchings (4″ feathers, 1.6″ vanes) and varying helical/offsets as well to see how much they affect the speed.
Other posts you may enjoy:
- Arrow Penetration Testing: Real Bows, Real Arrows, Real Results…Part II
- Heavy vs. Light Arrows: Downrange Speed and Power
- Penetration Testing: Why You Should NOT Use Foam for Comparing Hunting Penetration
- Helical vs. Straight Fletch: Speed and Deceleration
- Arrow Penetration Testing: Real Bows, Real Arrows, Real Results
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{ 7 comments… read them below or add one }
Micheal,
Enjoyed reading the article makes a ton of sense.
I happened to notice you dont have any fletching on your arrow’s.
Are you shooting FOB’S if so can you do an article on them.
I’m considering switching over?.
Thanks,
Bill
Bill,
I did use FOBs for some of the testing for this article, and I have used them in several other articles as well. For hunting I have used them and they are excellent for steering broadheads. There is a fletching review article here: http://archeryreport.com/2009/10/fletching-review-speed-drop/ where you can read some about them and I do plan on doing a more in-depth review of them in the future.
F.O.C. and arrow weight. I’ve been doing a lot of reading about front of center. My local archery shop, thirty plus years in the business in archery, said, “If it aint broken, don’t fix it”, if you can get your broadheads (fixed) to fly true, leave it a long. To me this sound real good, so my testing, I may add an additional ten grains screw-in from GoldTip to get the foc up to 10%. Now, arrow weight, some tell me I’m shooting a light arrow, I need to be over 400 grains plus, what I’m shooting is around 385-395 grains. So, what is an good arrow weight? Here it’s moose, black bear and caribou in Alaska. Also, my arrows are CX Maxima hunter 250/350, the 250 are 390 grains, where the 350 are 410 grains, all shafts are cut to 29″. Still learning this sport.
Rudolph,
F.O.C. is an often misunderstood and mistreated subject! While I generally believe in the same rule as your local archery shop, I also believe that experimentation and learning can lead to improvement. With my current arrows for hunting I’ve settle for around 13-15% FOC and they shoot outstanding, especially downrange and in the wind. A higher FOC can also lead to better penetration overall.
It would be better to give you an opinion on your setup if you shared more information, such as draw length and draw weight. In my opinion and with my hunting arrows, I tend towards a bit heavier arrow, around 450-500 grains at a 30″ draw and 70 lbs. draw weight. I like the added penetration potential and the stability downrange and in windy conditions. If I were only to hunt whitetails, I wouldn’t be as concerned about penetration, but my main game is elk which are much thicker in every respect. Of course with weight is a trade off in speed and everyone needs to find their best balance. My personal theory is to go a little heavier and also practice distance judging a LOT so that you don’t have to worry about speed as much.
Just found this article, but I am wondering if you’ve done any testing with a bow with lighter draw weight and length. I have a 23″ draw length at 50# and have been working on some testing. It seems that the converse of your findings is true for me. I am achieving better accuracy & higher arrow penetration with a smaller arrow shaft & lighter broadhead. I do not have technical equipment to gauge arrow speed so I am wondering if you’ve done any research on this, or if I can come and do some with you.
Mia,
I have done some testing, though not extensive, with lighter weight bows and what I have seen is that when properly tuned, they tend to follow the same efficiency increases. I definitely need to do more extensive testing and data collection though.
What I have found when working with people that shoot lighter weight and shorter draws is that their bows are often not properly matched to their arrows and thus more energy is lost and they become less efficient. This can really only be seen when using a chronograph for testing. I am not saying that this is the case with your setup, but it seems to be a fairly common issue.
If you have any testing data that you could share with me I would love to see it and also hear more about the equipment you are shooting. Also, if you would like to work with me on more testing, I will always take any extra help I can get! Currently I am working up some ideas for additional penetration testing and hope to get them going in the coming months. Hit me up at mike@archeryreport.com if you’d like to discuss any of this in more detail.
I’ve been doing a mess of perusing in regards to front of focal point. My nearby bows and arrows shop, thirty in addition to years in the business in bows and arrows, stated, “If it aint broken, don’t fix it”, provided that you can get your broadheads (altered) to fly correct, leave it a long. To me this sound true great, so my trying, I might include a supplemental ten grains screw-in from GoldTip to get the foc up to 10%. Presently, shaft weight, some let me know I’m shooting a light shaft, I need to be over 400 grains besides, what I’m shooting is around 385-395 grains. Thus, what is an exceptional bolt weight? Here its moose, dark bear and caribou in Alaska. Likewise, my shafts are CX Maxima seeker 250/350, the 250 are 390 grains, where the 350 are 410 grains, all shafts are sliced to 29?. Still studying this game.