How much kinetic energy is needed for elk?

[PAHunter]

How much kenetic energy does it take to kill elk with a well placed shot?  Easton's recommendations are:

25-41 Lbs KE...........Medium Game, Deer, Antelope.
42-65 Lbs KE ..........Large Game, Elk, Black Bear, Boar.
> 65 Lbs KE............Toughest Game, Grizz, Cape Buffalo.

I'm wondering if that sounds high to you.  For example a 60# bow shooting a 550gr arrow would need to launch it at 186FPS to reach the minimum for elk.  I would guess an average 60# bow shoots somewhat less than 186 (though I could be wrong).  And I suspect that most indian bows were below that kenetic energy. 

As I'm choosing a bow for elk hunting, I want to ensure that it has sufficient kenetic energy to 30 yards.  What is a reasonable kenetic energy for a selfbow for elk hunting?

[PEARL DRUMS]

I know a sharp cut on contact 2 blade head will penetrate fresh deer hide with under 2# of pressure. So a 60# bow with the right head should pass through an elk at 20-30 yards if you don't smack ribs on both sides.

[JW_Halverson]

I know a sharp cut on contact 2 blade head will penetrate fresh deer hide with under 2# of pressure. So a 60# bow with the right head should pass through an elk at 20-30 yards if you don't smack ribs on both sides.

And you only need to break the rib going in!.  Put all that kinetic energy into an arrow with a 1" diameter blunt and you will bruise a rib.  On the other end of the hyperbole rainbow: have a two blade cut-on-contact single bevel arrowhead that matches the rotation of the fletching, taper the shaft behind the arrowhead to reduce diameter of the arrow shaft (reduces friction once into the cut), match the arrow spine to the bow so that you have flawless flight, and you have maximized the application of that kinetic energy. I would recommend you look up Dr Ashby's reports on arrow lethality for some bedtime reading. 

It all comes down to poking a hole thru both lungs.  There is a video going around Facebook of an 14 yr old kid sticking an elk with his compound and the animal is down in under 10 seconds.  The bull was almost perfectly face on to him and the arrow struck at the base of the throat.  You can see the blood pour like Kool-Aid out of a pitcher.  If you think that is the money shot, go hang a 3/8 inch piece of rope from a tree...and if you can cut that rope 9 out of 10 shots AND you have xray vision where you can see the carotid artery in an elk, then go for it.  Otherwise, stick to the double lung shots.

Man, I love the way you are working everything out ahead of time, rather than waiting until you arrive at camp to figure out what you are trying to accomplish!

[PAHunter]

I know a sharp cut on contact 2 blade head will penetrate fresh deer hide with under 2# of pressure. So a 60# bow with the right head should pass through an elk at 20-30 yards if you don't smack ribs on both sides.

For sure! Unless I make some exceptional stone point bamboo arrows prior to then I will be using these babies.

[PAHunter]

@JW: Perparation is one of the things I enjoy most.  I know experience is the most important ingredient but mix perparation and experience and you have a lethal combination! 

I couldn't agree more on shot placement.  I been taking about 4 deer a year with modern equipment and only take broadside and quartering away shot opportunities.  I've had a good shot to kill success rate. 

Great points about the arrow and broadhead tuning's effect on KE!  The only thing I didn't quite follow was "arrowhead that matches the rotation of the fletching".  Do you mean aligning it with the cock feather or something?

I'll check out those articles for sure.  Here i am trying to ensure that my bow and arrow are producing more than sufficient KE to get the job done.  For example the Easton post suggests that my 50# bow shooting about 158 FPS woudl be signifigantly underpowered for elk.  I don't know what my recent 60#ers shoot (definitely much faster) but I wanted something to judge them against.

thanks for the input brother!

[adb]

Kinetic energy is the wrong way to think. Works for firearms, but not bows. It's all about penetration, which comes from mass and velocity, and the right broadhead.

And for bows at short distance like ours, it's mostly mass. Stickbows don't have high velocity, so the arrows need to be on the heavy side for hunting.

Think of it this way... would you rather get hit in the head by a golf ball going 50 mph, or a ping pong ball going 75 mph?

And shot placement is a given with any type of hunting. I've seen deer run away unrecovered after being shot in the a$$ by a 338 Win Mag.

[kleinpm]

Like JW said, you certainly are planning this all out ahead of time. Completely understandable since shots at elk are few and far between, even for those of us lucky enough to live in elk country.

With that being said, don't over think it. Elk are tough but if they're lungs/heart aren't able to pump blood they die like everything else. My previous neighbors kid killed a cow elk with a 35 pound recurve he found at a garage sale with an arrow he bought at Walmart to replace his other arrow. Yeah, he had one arrow to practice and hunt with. The arrow went in one side and out the other. He couldn't find the arrow and was bummed because he had to buy another one.

He got lucky in more ways than one, but i think it proves that an arrow shot from just about any weight bow is moving fast enough to have enough energy to kill just about anything.

Just my .02.

Patrick

[JW_Halverson]

Single bevel broadheads are either right hand spin or left hand spin....just like the helical spin on your fletching.  Match them and you improve penetration and bone splitting power.  Mismatch and lose approx. 10% penetration power.

[Danzn Bar]

Kinetic energy is the wrong way to think. Works for firearms, but not bows. It's all about penetration, which comes from mass and velocity, and the right broadhead.

I wonder what the variables are in the calculation for Kinetic Energy??  Mass and Velocity?  and you should always have a sharp broadhead.
Just IMHO....
DBar

[Danzn Bar]

Actually, if I remember my physics correctly..... Kinetic energy = 1/2 Mass X Velocity squared....  Therefore,  It does has a lot to do with penetration.  You both are thinking in the right direction. 
DBar

[nclonghunter]

Another consideration is the weight front of center. Get plenty of weight in front so it is pulling the arrow behind it, not most of the weight pushing from behind. If most of the weight is behind the center of length then any deflection is magnified and will stop penetration dead. The heavier front end also makes your feathers more effective as a guidance system by changing the center balance point of the arrow further forward.  The single bevel broadheads seems like a good idea, but I wonder if it adds a lot more to penetration. Super sharp cut on contact seems to be important to me. I use 100 grain brass inserts and 100 grain Muzzy Phantoms cut on contact with I think 10 grain per inch arrows. They weigh in a little over 500 grains. Good penetration with those, Good Luck.
 

[Mohawk13]

Honestly Guys...Leave the science at home when hunting Elk. If your arrows are in tune with your bow, you have a decent broad head that is sharp, and you can put an arrow where you want it placed...That is all there is to it. Yes, bigger than a deer, deeper chest cavity, heavier bone...

Its not rocket surgery or brain science, just get the arrow where it needs to go. Make all the same preps as hunting deer, and then study the heck out of elk..They are smart beasts..I would worry more about finding one to shoot than actually shooting one..They are big, but very elusive,,,

And don't sweat the science. Let your inner cave man out and go hunting...Let the compound shooters worry about kinetic energy

[Danzn Bar]

Ha.. I like that Mohawk.. "Its not rocket surgery or brain science, just get the arrow where it needs to go." 
I agree completely.
DBar

[killir duck]

one of my hunting buddies has been bow hunting elk for close to 30 years, he shoots mostly r/d fiberglass longbows, he told me not that long ago that he has lost 3 elk out of almost 40 he's killed with bows, they were shot with 65#+ bows and 600gn+ arrows he said that all 3 three were lost because of bad shot placement, i asked him what was the lightest bow he's ever shot an elk with, he said 42# with a 480gn arrows tipped with 150gn grizzlys, 20 yard shot, he got a complete pass through with the arrow hitting one rib on the near side, the elk only ran about 50 yards. i've only shot one elk with a bow and it was with a 62# fiberglass longbow with 550gn. arrows tipped with 155gn tuskers, it was a 55 yard shot and the cow just walk-trotted about 25 yards, looked over her shoulder and fell right there. it all comes down to shot placement and properly tuned arrows, without those it doesn't matter how much kinetic energy you've got

[nclonghunter]

Killir duck, I would like to hear more hunting stories of your buddies elk hunts. That's an awesome record and he must have a ton of elk knowledge. Wish I had grown up in elk country.