Arrow Speed and Kinetic Energy

[ADMIN]

Fast cars, fast computers, fast wide receivers, fast-drying paint, fast-acting weed-killer.....if it's fast, we love it. And when it comes to our archery equipment, it's no different. Show most guys a brand new bow, and their first question is likely to be "How fast does it shoot?" Right or wrong, speed is a major consideration for most archers. And it's great to see how advancements in materials and design technologies have made today's compound bows better, faster, and more fun to shoot than ever before.
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This is a thread for discussion of the article, Arrow Speed and Kinetic Energy, By Jon Henry. Here you can ask questions or make comments about the article.

[shortpants]

Thankyou for sharing this info with us. I thought it was a great article! I was wondering if I could get some of your thoughts on this topic I started? Thankyou, Jason
Long range arrows???

[Buffalobob]

Interesting article and as a physicist I would say that the only way to deal with impact dynamics is with momentum. However it is not really worth arguing about being as many of the K.E. rules of thumb correspond to good momentum numbers in the world of rifles. Most likely the archery numbers are also equivalent.

[SpencerSS]

You should read Ashby's reports. Penetration is paramount. Speed and KE don't amount to much. If you want the best arrow performance, perfect the arrow by his methods.

There are some really good tests done with comparisions of components(particularly broadheads) on thousands of animals. Very interesting results, like "the only variables to show differences in blood trail quality are shot placement and whether or not the shot passed through. Broadhead type showed no dicernable difference."


I've seen a 45@28" longbow out penetrate the top coumpounds @ 70-80lbs shooting 290-340fps. Because the traditional guy had well setup arrows and the compounds didn't.

If you really want to see something cool look up "arrow penetration, african elephant", You'll know when you find the right one. 3 pass throughs.

[1Hunter]

Originally Posted by ADMIN

This is a thread for discussion of the article, Arrow Speed and Kinetic Energy, By Jon Henry. Here you can ask questions or make comments about the article.

Jon.

Great article, Hot fast bows and hot fast women will wear you out.
I found many years ago with recurve bows, that the correct spined arrow
for your bow will shoot far better than the next best. Choosing the correct
Bow to fit the Archer is usually a good starting place.

Then along came the compound Bow. The rules didn't change, there were
just a lot more of them.

Again, Very nice Article

1Hunter

[MZmoose]

Im no physics major, but I have some real world experience. I too believe the momentum equation more closely fits the performance of an actual hunting arrow. Many long bows, and traditional recurves would have trouble reaching the kinetic energy figures listed to cleanly take the various game animals. They don't have much speed (less than 190 fps) but what they do have going for them is very heavy arrows. I have seen heavy arrows pass thru bull elk and sail out the other side, killing them quickly. The way I see it the broadhead is what kills the game, it cuts the tissue and destroys organs. The shaft is just a way of getting that broadhead to, and through the target. You can put that broadhead on a straw and shoot it at a deer or you can put it on a shovel handle and shoot it at a deer. Obviously this is an extreme example but the extra weight of the shaft and increased momentum will push that broadhead through more muscle and bone than a lighter fast one. Maybe someone should find a uniform test medium and use one broadhead on several arrows with increasing shaft weights (the shafts would have to be the same diameter to keep it fair) and then see if the penetration results compare to the kinetic energy formula or the momentum formula. Just a thought. As far as speed vs weight for time of flight and range estimation, you are 100 percent correct. Faster arrows help with string jump, and if your range estimation off a bit that extra speed will help. Great article.

[SpencerSS]

Dr. Ashby has some articles on the subject. Oh, and I shoot traditional. My 45lbs recurve launches an 800gn arrow at 130fps and it will smoke anything in NA. There are a lot of factors in penetration, arrow flight, mass, FOC, broadhead design, arrow system integrity....

Read this: http://www.alaskabowhunting.com/PR/A...t_Text_Web.pdf