Kinetic Energy

[Gator1]

I recently chronographed my Longbow:

48lbs
Shooting 500 Grain Arrow
29" Long

166 FPS...  I plugged this into a KE calculator, only to come up with 30.6 KE???

According to the chart, it recommends 40 KE for Deer Size Animals???

Any feedback would be appreciated..

  :confused:

[wingnut]

The chart was made by compound manufactures.  Your combo is plenty for deer shooting a good two blade or three blade cut to the point BH.  Heck I hunted elk this year with almost the same combo due to a shoulder problem.

Mike

[Gator1]

Thanks for the reply...

I was feeling kinda wimpy...  

[ChuckC]

Gator..  there are two current means of calculating the "impact potential" of an arrow that are being spoken about lately.  One, momentum and the other, kinetic energy.  They are calculated differently and put emphasis on different dimensions.  For one, speed is most important, for the other weight is at least equally important.    

Whatever the numbers come out to say, I have shot clean thru a 1.5 year old buck, broadside at maybe 12 yards, using a 45 pound Bear Grizzly, wood shafts of maybe 500 grains, and two blade bear head.   I am guessing you will have no problem with your set up for deer.  People have used your set up for much larger game as well.
ChuckC

[longbowman]

Gator,  You're going to find that the majority of people who shoot trad gear shoot very light weights and especially on this site.  They seem to do a good job in taking game so I guess you should be OK too.  I'm from old school that says shoot as heavy as you can handle accurately.  That saying seems to mean many things to many different people but I say what ever weight you can easily pull and hold you should be able to add 10# to that with very little effort.  Others say why would you when you can hit what you're shooting at with the light weight.  Unless there's some kind of physical handicap I don't see why the average man can't handle 55# plus with ease and even more with a little effort.

[Matty]

what is the actual formula for Kinetic energy?

[Richie Nell]

Gator....I have spent some time reading and listening to people who know more than me. To sum up kinetic energy as it relates to traditional archery I believe it is safe to say that if that phrase never enters your mind again you will better for it.
That is the importance of kinetic energy.  Nill.

[Charlie Lamb]

How fast it takes off ain't near as important as how fast it slows down when it hits something.  

You'll do just fine with what you are shooting. Hit 'em in the lungs, go pick your arrow out of the dirt and go get 'em.  

[SteveB]

30.6 with a 500 gr arrow is good to go.

Steve

[khardrunner]

KE=(1/2)mv^2 though it is not nearly as important as momentum (p). p=mv is the formula for momentum. This places the m and v as equal contributors. Since friction, sound, vibration, etc. does not effect mass and only really effects velocity, the conservation of p is much more important than the conservation of E (which can be lost as unusable due to the above factors). Velocity is a greater contributor to overall KE (which is why the compound guys love v so much) since it is squared. BUT since it is affected by virtually everything, it is not nearly as important as the mass part of the equation as far as penetration is concerned.

I hope that all makes sense to some degree. I'm sure you've read Dr. Ashby's stuff as well. He goes into great depth in some of his early stuff to explain why this is true. Either way, on a thin skinned animal like deer, you should see a complete pass through.
Happy hunting!