# Ft Lbs out of a recurve?



## JParanee (Oct 13, 2009)

My recurve at around 53 pounds produces 51 ft lbs 

But it's a very special bow


----------



## Aronnax (Nov 7, 2013)

JParanee said:


> My recurve at around 53 pounds produces 51 ft lbs
> 
> But it's a very special bow


Yes, yes, yours is a very special bow...

But, not counting JP's very special bow, based on the data I've run across (this is a particularly interesting subject for me) trad bows in general *store* about .9ft/lbs per lb draw weight. Good trad bows are also about 80-85% efficient at putting that energy into a 9gpp arrow fired off a shooting machine, ore a few % points lower if shot off the fingers. Also, more losses if you shoot with beaver balls... 

I would guess around .7 - .75 ft/lbs per lb draw weight actually into an arrow. The loner you draw length (power stroke) and the heaver arrow you shoot (improves efficiency) the better your numbers will be.

Blacky's bow tests are a real good resource for the most complete, scientifically recorded, data I've found. Pete ward also has some decent data, more real world testing, than scientific lab testing, though.

Here's an exceptionally efficeint example- http://www.archeryreports.com/index...em/ah-archery-acs-cx-copy.html?category_id=77
It delivers .78ke per lb draw weight to the arrow.

A little less than stellar- http://www.archeryreports.com/index.../3rivers-tomahawk-leagacy.html?category_id=77
.68ke per lb draw weight.

BM


----------



## Bluez (Mar 10, 2014)

JParanee said:


> My recurve at around 53 pounds produces 51 ft lbs
> 
> But it's a very special bow


JParanee,

I am digging that pic brother. Looks good :thumbs_up


----------



## Bluez (Mar 10, 2014)

Aronnax said:


> Yes, yes, yours is a very special bow...
> 
> But, not counting JP's very special bow, based on the data I've run across (this is a particularly interesting subject for me) trad bows in general *store* about .9ft/lbs per lb draw weight. Good trad bows are also about 80-85% efficient at putting that energy into a 9gpp arrow fired off a shooting machine, ore a few % points lower if shot off the fingers. Also, more losses if you shoot with beaver balls...
> 
> ...


Thanks so much for the help. That gives me something to go by. 

I really want to get into trad bows. I would love to shoot a 50# or 55# but will
probably get a 35# and change the limbs out as I get better and stronger.


----------



## centershot (Sep 13, 2002)

Velocity in fps X Velocity in fps X Weight of arrow in grains / 450240 - typical example 170 fps X 170 fps X 500 gr = 14450000 / 450240 = 32 ft/lb KE (why most recommend cut on contact broadheads).


----------



## JParanee (Oct 13, 2009)

Bluez said:


> JParanee,
> 
> I am digging that pic brother. Looks good :thumbs_up


Thanks Man 

New camera reall impresses the hell out of me


----------



## MrSinister (Jan 23, 2003)

Yup start out light and work your way up. I shoot 50lb well today but it took me a long while to get there. Took about two years to get it all working well.


----------



## JParanee (Oct 13, 2009)

Aronnax said:


> Yes, yes, yours is a very special bow...
> 
> But, not counting JP's very special bow, based on the data I've run across (this is a particularly interesting subject for me) trad bows in general *store* about .9ft/lbs per lb draw weight. Good trad bows are also about 80-85% efficient at putting that energy into a 9gpp arrow fired off a shooting machine, ore a few % points lower if shot off the fingers. Also, more losses if you shoot with beaver balls...
> 
> ...


The ACS bows do perform very well and Larry is a great guy 

If your interested in longbow limbs I know that I will be seeing some info on an updated Raptor LB soon


----------



## Borderbows (Apr 4, 2009)

Your not going to get any more energy out if its not in there 8n the first place.
Every trad bow has a dip in the dfc. Which lets it down when it comes to energy storage.

Pete ward has a review of the CH. But he also has a DFC of the only bow what doesnt have that dip.
http://peteward.com/2014 reviews/Test CovertHunter.html


----------



## BarneySlayer (Feb 28, 2009)

Great picture Joe!


----------



## JParanee (Oct 13, 2009)

BarneySlayer said:


> Great picture Joe
> 
> Thanks Barney
> 
> Here is a draw force graph for those that are interested


----------



## traditional1970 (Jan 5, 2009)

most bows will produce 25-45 lbs KE and hunting weight of 40-55lbs...remember a good shot with a cut on contact blade is the key...


----------



## Beendare (Jan 31, 2006)

Bluez said:


> This may be a stupid question so I apologize in advance if it is.
> 
> In a 50 or 55 lbs recurve bow what sort of kinetic energy or ft lbs could
> you get out of it? I know some crossbows can get 90? or so and the compounds
> ...


i think you are looking at it wrong- if KE meant anything...and arrow with a KE of 70ftlbs would be great right? Well heres the catch...a 500gr arrow and a 300gr arrow can generate appx the same KE from the same exact bow [the heavier arrow will always have a tad more as it absorbs more of the bows energy] The 300gr arrow can flex and practically bend in half penetrating little...while the heavier arrow blows through. KE doesn't explain the performance of the extreme ends of the different arrow weight categories.

Bottom line- Arrow weight is a better indicator of performance on game than KE.

A tuned medium weight arrow 8-9GPP will perform well in a 50# recurve....10 gpp will perform a little better...so it goes.


----------



## Aronnax (Nov 7, 2013)

Beendare said:


> i think you are looking at it wrong- if KE meant anything...and arrow with a KE of 70ftlbs would be great right? Well heres the catch...a 500gr arrow and a 300gr arrow can generate appx the same KE from the same exact bow [the heavier arrow will always have a tad more as it absorbs more of the bows energy] The 300gr arrow can flex and practically bend in half penetrating little...while the heavier arrow blows through. KE doesn't explain the performance of the extreme ends of the different arrow weight categories.
> 
> Bottom line- Arrow weight is a better indicator of performance on game than KE.
> 
> A tuned medium weight arrow 8-9GPP will perform well in a 50# recurve....10 gpp will perform a little better...so it goes.


I think I understand what you are saying, but I don't think you are saying it right. A really heavy arrow with 0 ke won't kill anything. I think momentum is what you are after, and yes, that is what actually pushes the arrow through a target. But momentum and ke are close cousins. You can't have one without the other. 

The bows limbs don't store momentum. They store energy. You transfer energy from your muscles into the limbs, the limbs store this potential energy until you loose the string. Depending on the efficiency of your setup, most of that energy (normally 75% to 85% of it) is transferred to the arrow. When the arrow is in motion, it has momentum.

Also, a heavier arrow doesn't necessarily mean it's stiffer. There are plenty of flimsy (weak spine), heavy (high gpi) shafts out there, and there are some really stiff, light shafts. A stiff light shaft will deflect the least under impact with something solid. If you are not hitting anything very solid, as in a good broadside shot, then it doesn't really matter much.

http://archeryreport.com/2012/01/kinetic-energy-momentum-arrows-simplified-approach/

Of course those studies are done with a compound bow, but the idea is the same, just with much, much, lower values.

BM


----------



## Bill 2311 (Jun 24, 2005)

Look towards momentum, not KE. 
An average 45# recurve shooting 175 fps with a 400 grain arrow will push a sharp two blade, cut on contact head, through the rib cage of a deer.
It is not necessarily a matter of momentum or KE, but how it is applied. My compound produces over 90 ft/# of KE, but I get so much because of the speed. KE figures really focus on speed. 
My recurve does not even come close to that. It shoots a 475 grain arrow at 185 fps. Still pretty good for a recurve, but for it I only shoot the Zwickey heads in order to maximize the momentum it produces. With the compound I can shoot a three blade Wasp and still not worry about a lack of pass through.
Unfortunately I think too much emphasis is placed on KE.
The tried and true formula for traditional gear is 8-10 grains of arrow weight for every pound of draw weight, with a cut on contact head. All things the same, cut on contact penetrates better than chisel points, and everything penetrates better than mechanicals. Likewise a two blade penetrates better than three and three penetrates better than four.
I would say that if you shoot over 55#, a three blade is great, but for me, I prefer to stay with the two blade, just in case it hits bone.


----------



## Roger Savor Sr (Feb 16, 2014)

Why anyone archery hunter bothers to calculate and worry over Kinetic Energy is beyond me. It basically has nothing to do with penetration.


----------



## Beendare (Jan 31, 2006)

Aronnax said:


> I think I understand what you are saying, but I don't think you are saying it right. A really heavy arrow with 0 ke won't kill anything. I think momentum is what you are after, and yes, that is what actually pushes the arrow through a target. But momentum and ke are close cousins. You can't have one without the other.
> 
> The bows limbs don't store momentum. They store energy. You transfer energy from your muscles into the limbs, the limbs store this potential energy until you loose the string. Depending on the efficiency of your setup, most of that energy (normally 75% to 85% of it) is transferred to the arrow. When the arrow is in motion, it has momentum.


 I never claimed to be a mechanical engineer...so maybe I'm stating it incorrectly but the point is; You don't need much bow to be effective hunting if you are using a sufficiently heavy tuned arrow with efficient BH.


----------

