? about kinetic energy
04-15-2004, 01:22 PM
#1
Thread Starter
Join Date: Mar 2004
Location:
Posts: 13,082
? about kinetic energy
Is it possible, and I don't think it can be, to have more kinetic energy than your pull weight....I will explain..
Good friend of mine shoots 70 pounds, 392 grain arrow, getting 292 fps. If I am doing my math correctly, that equates to 74 pounds of kinetic energy. Something doesn't sound right with that......
Good friend of mine shoots 70 pounds, 392 grain arrow, getting 292 fps. If I am doing my math correctly, that equates to 74 pounds of kinetic energy. Something doesn't sound right with that......
04-15-2004, 01:33 PM
#2
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: ? about kinetic energy
It's very possible to have more KE than your draw weight with today's cams. If you've got a fairly long draw length, it's not only possible, but probable.
Your draw weight is only how many pounds the scale hits while pulling the bow. But you need to understand force draw curves to understand how energy is stored. The sooner in the draw the cam hits peak weight and the longer the draw weight dwells at peak during the draw before letoff, in other words the steeper the slopes and flatter the top of the curve is, the more enegy is stored. Some of these cams now can store well over 90 pounds of energy at 70 pounds draw weight. And they can be darn tough to pull.
Someone like me with a huge, long draw can pack a lot of energy into the bow. I get energy levels with an easy pulling, round wheel bow that some short draw guys have to use hard cams and 70 pounds draw to match.
Your draw weight is only how many pounds the scale hits while pulling the bow. But you need to understand force draw curves to understand how energy is stored. The sooner in the draw the cam hits peak weight and the longer the draw weight dwells at peak during the draw before letoff, in other words the steeper the slopes and flatter the top of the curve is, the more enegy is stored. Some of these cams now can store well over 90 pounds of energy at 70 pounds draw weight. And they can be darn tough to pull.
Someone like me with a huge, long draw can pack a lot of energy into the bow. I get energy levels with an easy pulling, round wheel bow that some short draw guys have to use hard cams and 70 pounds draw to match.
04-15-2004, 01:45 PM
#5
Join Date: Dec 2003
Location: Kansas
Posts: 316
RE: ? about kinetic energy
Also keep in mind that cams, by design, give you a mechanical advantage, which actually increases the energy stored by the bow. Think of a teeter-totter. If you balance it right, you as the 200 lb dad can go back and forth with your 40lb kid, of course you will be sitting very close to the middle and your kid will be hanging off the end. This is mechanical advantage.
JMAC
JMAC
04-16-2004, 06:02 AM
#8
Boone & Crockett
Join Date: Feb 2003
Location: Lehigh County PA USA
Posts: 12,157
RE: ? about kinetic energy
I get energy levels with an easy pulling, round wheel bow that some short draw guys have to use hard cams and 70 pounds draw to match.
Which is sometimes why we don't see eye to eye
Which is sometimes why we don't see eye to eye
However, RB brings up an excellent point that I believe is most often overlooked. Each of our individual setups tend to bring us only a certain perspective on any given issue. The key is to recognizing that fact and compensating for it.
04-16-2004, 07:12 AM
#9
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: ? about kinetic energy
So, what are you saying, Frank? Just because I have a 33" draw I can't relate to someone with a 26" draw? Remember, I've had ALL draw lengths under 33"! I had a 26" draw.... once.... a long time ago..... when I was 10, maybe.... about 7 years before Allen invented the compound.
