Concerns regarding speed and kinetic energy

[Cameron Unruh]

#3452

I have some concerns regarding my bows and what kind of Kinetic energy that I am getting. I borrowed a chrono to check my speed and using T.J.Conrads book…The Traditional Bowhunter’s handbook I calculated my Kinetic energy. And I am concerned with the results.

First Bow: Tomahawk SS 58″ 55@28 I draw 27″

Results Arrow 628g speed 140fps 27 ft lbs kinetic energy

Results Arrow 520g speed 155fps 27 ft lbs kinetic energy

Fastflight string

Homemade bow: Bingham R/D 62″ 60@28

Results Arrow 628g speed 154fps 33 ft lbs kinetic energy

Dacron String

Homemade bow: Bingham R/D 62″ 65@28

Results Arrow 628g speed 163fps 37 ft lbs kinetic energy

Dacron String

I was disappointed with the speed especially from my Tomahawk which boasts of much greater speeds on thier reports.

How do these numbers compare to others? Are they below the hunting standards for taking game?

[Hiram]

#20107

I am impressed with your homemade Bows!!

You must remember that pre-load has a lot to do with performance. The LB may not be the best choice by design to accomadate your shorter 27 inch draw. The Recurves evidently have more preload and make up for the short draw length somewhat.

Some R&D LB’s have more preload than others. You might investigate which one might serve you the best according to your draw length requirements.

Try this, Draw your LB back an inch more than your drawlength and see if the increase is more than 4 fps or so. This may indicate that it may well be more suited to a longer draw.

As far the ability to be effective in field on live animals? Shoot as much as you can and be in control with relative accuracy to your query. I hunt Elk with 50 pound Recurves but I use FF strings and have high performance set-ups. I keep my arrow weight around 12 grains per inch on larger stuff like Elk and have had very good success, never have lost an Elk I put an arrow into (knock on wood) with good shot selection. I personally would not have a serious problem hunting Whitetails with your Longbow at the arrow weights and speed you posted but would keep the shots close, within 20 yards or so. The third Bow you mentioned would be a very capable Elk Bow!

[skifrk]

#20521

If I remember right to get these number in a chrono most will try and use a mechanical release and shoot the arrow indoors for these results since sun and other environmental variables can affect the results of a chrono. if you are shooting only a 27″ draw you might be able to go to a shorter bow to get more pre-load in the limbs.

[wildschwein]

#20550

Hullo Cameron. Just wondering if you have taken any big game with any of the bows you mentioned above, especially with your Tomahawk?

I ask because if you have taken game with any of these bows, and taken them without any difficulty, then I wouldn’t worry myself to much over the math. I have seen photos of men like Dale Karch with critters ranging in size from Musk Ox to Water Buffalo, and all taken with the same series of bow (although probably different poundage) that you yourself own. Not to mention the number of Elk, Moose, Grizzly and so on that have been taken with self bows, which I doubt would perform as well as the last two bows you mentioned in your tests.

The math is a nice thing to know, but I wouldn’t get myself worried about it.

[Cameron Unruh]

#20584

I have yet to take any big game with any of my bows all small game at this point. Living in California and hunting public land is not as exciting as I see taking place in other states. I have hunted for 11 years and never drawn on a buck. I have taken one small pig but it was with compound before going trad.

I often see in the TBM 12 year old kids taking a nice buck it drives me nuts.

To update the numbers I went back and began to purposefully draw to 28 inches and pull through the draw rather than my typical dead release. My Tomahawk when from 140 fps to 155 fps and from 27 ft lbs to 33 ft lbs. My 65 pound bow jumped up to 172 fps.

[wildschwein]

#20614

I totally understand your frustration Cameron. I went four years without taking big game with my bow. And I also understand your worries about your equipment. Due to hand injuries I can only shoot low poundage bows. But last season I put a 550ish grain arrow through a 250ish pound Muley buck’s shoulder blade at thirty yards. My bow only pulled 40 to 43# at my draw, and I doubt it had any more uummphh than the poorest performing bow you mentioned above.

[Cameron Unruh]

#20739

Thanks for the encouragment…due to the fact that I shoot at mostly small game I have gotten to be fairly accurate. I can hit ground squirrels on the move and this past year managed to connect on a large number of quail and several dove, none in flight but I will accomplish that as well.

When I do have the opportunity to draw on a big buck I want to make sure that my equipment can do the job.

[wapiti792]

#20757

I believe that any of your bows will kill anything in North America. Read Dr Ashby’s stuff here in regards to heavy arrows and penetration as well as FOC. For instance, using a heavy wood arrow and a 250 gr broadhead (650 gr total arrow weight)I have killed elk, whitetails, and bears. Momentum is much more of a concern than true KE. Sharpen up a broadhead and go hunting…there is nothing in California (or N America) that can hold any of those arrows you mentioned. Good luck!

[Bruce Smithhammer]

#20758

Cameron – I’d say your arrows certainly seem plenty heavy for the small game you’re going after. What’s your FOC?

Personally, I prefer to think about momentum, rather than kinetic energy.

Can you be more specific about what your actual concern is? Not having enough force for larger game?

[Cameron Unruh]

#20780

I have not calculated my FOC but my arrows are Carbon Express 250 with 250g field points and 250g BH’s. I guess the bottom line was that I was disappointed when I realized that I was shooting 140fps at my draw with the 628g arrow. 140fps just sounds slow and I was not sure it would have the necessary force to effectively take larger game. I am learning that I may have an opportunity to hunt pig on some private land and I want to bring home the bacon not just chase it off.

[Bruce Smithhammer]

#20787

Cameron wrote: 140fps just sounds slow and I was not sure it would have the necessary force to effectively take larger game.

Heavier arrows will tend to be slower. But heavier arrows will also pack a lot more punch, or momentum. Despite the popular bumper-sticker jingo-ism, speed isn’t actually what kills. Speed is one factor of momentum, and it’s momentum that kills.

My advice is not to get too hung up on chronographs. I used to graph my bows, I really couldn’t care less any more. I shoot a #57 recurve, with a 600+gr. arrow (24% FOC) and a 2-blade broadhead. I know it’s a very powerful combo that packs a whallop, and I have no concerns about having sufficient penetration on N. American ungulates or pigs.

Rather than speed, I’d suggest paying attention to the amount of penetration you’re getting with that setup at normal hunting distances (and increased FOC will help with that). You can even buy a side of meat (ideally w/bone), and shoot into it at 10, 15, 20 yds. and see what happens.

But in the end, keep in mind that many, many animals have been killed with bows that aren’t any “faster” than yours.

[Konrad]

#20965

In my humble opinion, the question is not so much about speed or kinetic energy. The question is really about getting close, accuracy and using a dependable, sharp, two edged broadhead.

After you have seen the results of your first kill, the questions you raise will be moot.

Your concerns make for interesting debate and commentary but they will evaporate when you see real results.

Of course, you know how to get to Carnegie Hall?

Practice, practice, practice…

[Don Thomas]

#29916

My advice is simple: Stop worrying about it and go shoot your bow. That’s how I do it. Don

[Cameron Unruh]

#29950

Good advice – I will follow it.

[Don Thomas]

#30574

If I sounded unduly flippant, I apologize. It’s just that I’ve gone through a long career without ever chronographing an arrow, calculating KE, or bare shaft tuning a bow. 95% (?99%?) of blown shot opportunities are due to pure pilot error and have nothing to do with these technical variables. If an arrow flies well from my bow, I hunt with it. If it doesn’t, it becomes a carp arrow or a tomato stake. Traditional bows and arrows are not precision instruments–they’re sticks and strings. The route to success in the field comes from archery practice and the development of good hunting skills through experience. Of course all this is just MHO, and others are welcome to disagree. But this approach has worked well for me. Don

[Cameron Unruh]

#30585

Don, The advice was truly what I needed to hear! Since I have not taken big game I was unsure of how to know the effectiveness of my setup, and I have read a fair amount about what some expect out of their equipment. My arrows hit the mark and seem to do so with authority. It gives me more confidence to hear from your experience.

thanks

[Cameron Unruh]

#30592

This is more what a day of hunting looks like for me. If given the opportunity I will hit the mark. I just wanted to make sure that my arrow will be as effective.

[Konrad]

#30733

I read that Fred Bear said success in a bowhunter is built one success upon another. Beginning with small game, confidence grows with each success. He suggested hunting does for the same reason. A small doe will aptly show the effectiveness of your equipment (A beautiful outfit if I do say so myself!).

Not only does the taking of does prove the metal of your rig; it also gets the archer more confident while being in close proximity to big game. Confidence (or the lack thereof) is one of the largest factors in bowhunting success.

A stout arrow tipped with a sharp, two edged blade, even when launched at modest velocity will bring down any North American big game…if you are close enough.

What one man can do, anther man can do.

[Jason Wesbrock]

#34366

I’m not sure how I missed this one earlier.

Personally, I’m always skeptical whenever people want to define lethality by some ratio or number spit out by a chronograph or grain scale. A few year ago I saw a chart on an arrow manufacturer’s web site that listed the minimum Ke required for a lethal shot on a bull moose was 60 foot-pounds. I guess the bull on my wall didn’t get the memo. According to some other measures, I probably shouldn’t be able to shoot through anything bigger than a chocolate Easter bunny. It’s funny how dogma doesn’t always reflect reality.

In the end, I concur with Don’s advice. I know my equipment is more than up to the task at hand. That’s probably why I spend a lot of time working on my shooting skills and pretty much zero playing around with different arrows and such.

[bamboo]

#42622

there is nothing wrong with a guy knowing or trying to find out what makes a bow “tick”

and practice and accuracy are of the utmost importance–but dismissing the guys questions with— just shoot-just do like me and you’ll be fine–isn’t fair!

i say do the math cameron–that knowledge won’t make less of a bowhunter–tune your set -up for optimal penetration–aim for the perfect set up –don’t settle just because others have!!–my advise is to shoot the heaviest best tuned sharpest broadhed and arrow that YOU are accurate with!!don’t get hung up on speed -but IMO speed won’t hurt

good luck–keep working on this and you’ll do fine

—————————–mike

[Author]

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