Kenetic energy
 

Has or does everyone figure there KE.I did the formula speed X speed X weight of arrow and divide by 450240.Came out to be 52.I' m shooting CXL 150 27" 60lb .Is that enough for a good pass through a white tail or should I go to a heavier shaft and sacrifice some speed.I know that everyone has different ops about it.would like some input Thanks for your time.

RE: Kenetic energy
 

52 ft. lbs. is plenty. You' d be pushing your luck if you shoot mechanicals, but a fixed blade should have no problems. If you like to play around with different shafts, weights and speed, heres a good site that will save you some math. http://home.att.net/~sajackson/archery.html

Mine runs between 79 and 83 depending on tip choice.[:-]

RE: Kenetic energy
 

Goldenarm.......
I ran some numbers and I' m not sure exactly what components you have on those arrows, but say a 27" CXL 150 at 27" with 4" vanes, nock and insert only weighs in at about 245grs without a point. (Lighter if you are using something smaller than a 4" vane) I can' t imagine they' d spine very nice with anything at or over 100grs for a head weight........which puts you under 350grs total finsihed arrow weight........no biggie with the right broadhead. My concern is the shaft selection. CXL 150s are VERRRRRRRRRRRRRYYYYYY fragile. Like pretzel stick fragile when it comes to any abuse. For that reason alone I would consider a different shaft.
To get a Ke level of 52# you have to be shooting this shaft in the 260fps range.
You could beef up a bit on the shaft......maybe like a CX-200 to give you just a bit more Umph and a MUCH tougher shaft.
Also keep your eyes firmly planted on the good cut on contact fixed blade style....they' ll compliment your set-up nicely.

If you want to play with some numbers for various shafts,weights etc. Go to www.bowjackson.com You' ll find all sorts of good calculators there to help you " See" an arrow before you buy or build it.

RE: Kenetic energy
 

Hey Nub What set up are you using to get that much K/E?

RE: Kenetic energy
 

spank: 70 lb. Pat DC @ 29" draw. ACC 3-60 shafts, total weights between 361 and 415 grs I believe. (can' t find my notes) speeds between 300 and 315 depending on tip used.

RE: Kenetic energy
 

Matt makes a very valid point. Also when it comes to KE, bows which are maxed out have a set amount of KE unless extreme variables are taken in arrow weight. The best way to increase KE out of a bow is to increase poundage. IF your bow is maxed out, one can usually tweak a bow and gain a few extra pounds without damage to the bow. This is done with twisting the cable(s)/string but make sure to check you tiller and cam(s) timing nock travel and tuning.

When you increase arrow weight with the same poundage, you decrease the speed of the arrow thusly in the formula, KE stays relatively the same. The opposite is true if you decrease arrow weight, you gain a little speed thusly retaining about the same KE. When extremes are taken in weight in either direction is when KE can be manipulated.

If you can tweak a few pounds and increase arrow weight, your KE should climb a little. It is recommended that one use 45 ftlbs of KE for whitetail sized animals and 55 ftlbs. of KE for elk sized animals tho in history, many animals have been taken with less. A good hit is the most important agenda for lower KE shooters and marginal shots are absolutely off limits.

Again, on Matt' s recommendation alone, you arrow shaft selection should be reconsidered.

RE: Kenetic energy
 

I was shooting a Hoyt Deviator when they first came out. I was shooting 31" 2512 shafts with 100 grain points and vanes, 30" draw, 67 lbs, and my speed was 285 fps. That translated into over 94 ft/lbs of KE. I' d hunting anything with that short of cape buffalo.

RE: Kenetic energy
 

thanks agian for all the input everyone has given me.To Matt/Pa ,I don' t know how you came up with those #s cause I gave you the info,but anyway thanks again for the input.Goldenarm

RE: Kenetic energy
 

I shoot a hoyt magnatec 70# with a 27 1/2 inch draw 28 inch 2315. 125 grain tip 547 grains total weight, on a scale. It comes off my bow at 231 f/s through a crono. My bow is at it' s max weight. Though paper it just leaves the three cuts from the fletchings right off the bow and at about 12 feet.

RE: Kenetic energy
 

better re-check those numbers - a little off:D

RE: Kenetic energy
 

Rack: Amazed me too. He' d have to shoot a 520 gr. arrow @ 285 fps.![:o] Can a Hoyt do that at 67 lbs.?[>:]

RE: Kenetic energy
 

Heres an easy to use calculator for finding your KE as long as u know 1) arrow weight 2) arrow speed. [link]http://www.goldtip.com/Archery/calculators/kinetic.html[/link]

RE: Kenetic energy
 

So get enough foot pounds of K.E. and you won' t have to worry about anything. If you get up to 65 or so you' re shooting fast enough or you have enough mass to quiet the works and you can kill anything you shoot at.:D Well... ALMOST but not exactly. Poundage will help if you can shoot it comfortably. We short arm little rascals have a hard time doing it though(beefing up the K.E. One of my bows shoots about 73 fps(525 grain arrow)... the other about 65(425 grain arrow). I say you' re borderline low on K.E. but it' s enough to kill but you have to have the right broadhead and then you' ll have NO problem. Stay away from mechanicals and lean towards cut on contact and you' ll be OK. I don' t know your shaft and didn' t look it up but would tend to accept what Matt says.

RE: Kenetic energy
 

If you keep your set-up the same, (at 52 KE) stick with fixed blades. Matts suggestion of a CX200 is very good. You' ll find if you play with the calculators you really don' t change KE much by using heavier arrow.(just alittle) If you want more KE you could: Buy a more effiecent bow, increase your bows poundage, or/and make sure your accessories are not robbing some of your bows power. Some examples; having a large peepsight(heavy and bulky), having a rubber tube on your peep, some people put on extra silencers or have unneeded nock sets or even a kisser button they really don' t use. Keep your string light and clean, it will help.

Good Luck!

RE: Kenetic energy
 

My draw and arrow are 27' ' . I' m shooting Carbon Extream Terminators that weigh 10.7 grains per inch, 3 7/8' ' veins. My arrow comes out around 435 grains with the 100 grain 3 blade Muzzy. My speed is 240fps. This comes out around 55 foot pounds.With a good broadside shot will this produce pass throughs or leave my arrow sticking out?

RE: Kenetic energy
 

According to the sight to the link above 40 is enough for a pass through on a whitetail deer. I got 56 ke for your speed and arrow weight with there calculator.3

(copied from there sight)
Forty (40) foot pounds will allow a total pass through on a whitetail deer.
Fifty (50) foot pounds of kinetic energy are suggested for hunting elk.

RE: Kenetic energy
 

Rack, and Nub,

A 31" 2512 shaft weights 318.37 grains
Aluminum Insert weights 52.00 grains
Field points 100.00 grains
Super Uni System/Nock 16.00 grains
Three, 5" , plastic vanes 32.6 grains


That' s 518.97 grains. I think glue and hot melt can easily make up 1.03 grains.
So you see, it' s easy to reach the 520 grain mark. And yes, it shot 285 fps at 67 lbs. I HAD to shoot it thru a chronograph numerous times at 3-D shoots. I had been shooting it at 70 lbs but had to back it off due to Oklahoma State Archery Association rules about not exceeding 288 fps. It was shooting at 290 fps at 70 lbs. When I shot Gold Tips, It shot 315 fps at 65 lbs. It was a double " hard" cam bow with a severe reflex riser and a brace height around 5 1/4" if I remember right.

So I do believe the correct KE numbers are 93.809968 lb/ft. Close enough to 94 for me.

RE: Kenetic energy
 

Holy smokes batman! That Hoyt Deviator was faster than anything Hoyt makes today! Including the Supertec with an IBO of 330+ fps[:o]

RE: Kenetic energy
 

I think the biggest problem we have with bowhunters today is everyone wants to push the limits. They want the fastest, or the lightest arrows etc etc. If we can kill a deer with anything from 50 fps to 90 fps... everyone says 50 is MORE than enough. (maybe it is under ideal situations) People also start hedging. I believe the common statement of 50 being more than enough to get a passthrough was meant and said with a cut to the tip on contact broadhead. Then some guy fudges with a Thunderhead or Muzzy, then some guy fudges with a mechanical, then some guy fudges to 47 pound etc etc etc. Fix up the best killing machine and tools you can handle comfortably and don' t cut corners and you' ll be fine. No matter what the say, you can' t make a silk purse from a sows ear.

RE: Kenetic energy
 

Goldenarm,

You have more than enough KE to kill a whitetail. Hit ' em in the right spot, with a very sharp broadhead, and you' ll have no problems. If you' re shooting good with what you have (broadheads attached), I' d leave it alone. If not, work on getting the right spined shaft and tune the bow to perfection.

RE: Kenetic energy
 

Doug, it was a very unforgiving bow. I shot it with fingers too. If I wasn' t spot on with my form, it was hell getting it to group. I had to shoot it at an indoor tournament one day because my indoor bow was down. The club had a fairly new target wall of cardboard and I was shooting clear thru it and had to drop out. I once shot a robin hood with it at 30 yards, and drove the 2512 shaft almost all the way thru the other one. Sucker hit hard. It was a dual hatchet cam bow w/ 65 percent let off. Very small valley with a rock hard wall.

Back in those days, speed was the most important thing to manufacturers. I think they got away from that a little bit to concentrate on both speed and forgiveness.

RE: Kenetic energy
 

What year did they make the Deviator? I bet I could pick one up for pretty cheap on ebay. I like those older bows , especially ones with alot of snot!:D

RE: Kenetic energy
 

I bought mine in ' 98 or ' 99. They made two versions, the regular Deviator, and the Deviator XL. I had the latter, 42" axle to axle.

RE: Kenetic energy
 

I think your chronos might need some calibrating:) even a Hoyt tech tells me there`s noway he knows to make that arrow go that fast off that bow.;)

RE: Kenetic energy
 

I agree with davidmill , you have enough energy but should stick to cut on contact 2 blade heads like magnus , steel force , ziwicky , simmons , and the like . They are all great heads .

RE: Kenetic energy
 

I apologize for contributing to the hijacking of this thread! But i just had to weigh in....:)

I have to agree Danny.....Unless you got THE fastest Deviator in the history of mankind something is screwy with those numbers.

Hoyt lists the Deviator at your specs (70#/30" ) at 9grs/lb. at 239-245fps. ( THAT' s with a 630gr arrow).........which equals 80-84ft lbs of KE. Nothing to sneeze at for sure, but that' s at 70# not 67# and with an arrow 100grs HEAVIER than yours.
WIth a 520gr arrow and your specs of 30" /67# you should be looking at something like 78 ft lbs of KE ,and that' s top end. Again nothing to sneeze at, but a far cry from 94ft lbs of KE!

Look at it this way........to get that number you quoted you are looking at a bow that would need an IB0 rating of about 352fps!!!! (I don' t think there is a Hoyt rep alive who would tell you a Deviator at 30" /70# could shoot over 350fps.

If I had to guess, you actually DID see a 285 from that bow at 67#/30" but there is almost ZERO possiblity that that arrow could weigh 520grs.

Heck my Pro38 Dual Cam BowTech had an IBO speed rating of 333-340 and I had it going 336fps with a loop only (339-340 bare string) This bow with a 474gr arrow would only do 290fps and that' s a full 46grs lighter than your arrow, AND I was shooting 30" /70#!

Granted the Deviator was a beast of a bow........but lets not get carried away!;):D

RE: Kenetic energy
 

he is probably just about ready to put that hoyt up on Ebay:D

Figured he could get top dollar for it;)

RE: Kenetic energy
 

:D

RE: Kenetic energy
 

NOT saying that cut to tip heads are " BAD" , just saying that at higher arrow speeds, a broadhead with less surface area (most NON cut to tip heads....shorter blades) will GENERALLY penetrate as well or BETTER than a cut to tip head.
Velocity is the key. The faster the arrow, the better for replacable blade heads. Slower arrows work better with cut to tip heads.
50 lbs is more than enough to kill deer...CLEANLY. just make sure you make a good hit. PLACEMENT is MUCH more important than KE or broadhead type.

RE: Kenetic energy
 

I have to disagree with ya Mahly. Try pushing a cut to tip through a piece of carpet, cardboard, old sweatshirt, hide, anything. Then try and push a fixed blade with one of those trocar tips thru. No comparison, the cut to tip head wins every time. Also when comparing total surface area, I' d say my 125 Muzzys are substancially larger than my 125 Montecs.

I will agree that cut to tips work better with slower arrows.

RE: Kenetic energy
 

Just a quick question here, what would you say is the minimum KE for shooting mechs?

RE: Kenetic energy
 

I' m with Nub.....I disagree. They go through like a hot knife goes through butter.

Taz...most say 55lbs of KE is enough, but if it was me...if I ever did shoot a mech, I' d personally want to be higher.

RE: Kenetic energy
 

Okay two more questions for the gurus.

1. What weight arrows are used to establish the IBO speed of a bow?

2. How would you determine approximently how many FPS are lost per gram of arrow weight above the IBO weight?

RE: Kenetic energy
 

Hard to answer a blanket statement regarding Mechs as there are so many diff designs and cut diameters.

heads like the snipers and the small 2 blade rockets can IMO be shot at under 55 lbs.

And swing back 3 blade heads with large 1.5" and 2.0" cuts should IMO be used with more ke.

RE: Kenetic energy
 

Guys, you prove MY point. Pushing a cut to tip through leather IS easier....you are at the extreme slow end of the scale (less than 1fps...HOW does THAT relate to the real world?). As speed increases, it gets eaier and easier to go through the leather. When shooting an animal, you have to go through something much thiker than a peice of leather. The entire head is surrounded by matterial. The HUGE surface area of the cut to tip heads causes more drag than the replaceable blade heads (or even a mech head...BLASPHAMY....or is it?).
like cutting through a block of cheese, the less surface area, the easier it is to cut. hence cheese cutters are VERY dull, but have VERY little surface area (peice of wire).
Try to cut grass with a razor moving at 1 fps...then open up the weedwhacker with it' s super dull mono line...a bit easier...even though the razor has a MUCH higher KE (It' s weight, plus the weight of your arm/body).
None of this REALLY matters, as long as you put the head where it belongs. Indians killed deer with jagged rocks tied to bent sticks for cripes sake!

RE: Kenetic energy
 

No,matter how ya slice it pal, a cut will out penetrate a punch.

RE: Kenetic energy
 

If a 630 grain arrow that weighs 110 grains heavier than mine, but still get up to 245 fps, what is so difficult in believing a 110 grain lighter arrow will do 285? And, you are forgetting that the " speed x speed" portion of the equation is an important factor in KE. I don' t care if your arrow is 1000 grains, if it' s traveling slow, it' s not going to have the KE. If it' s traveling fast, use it for anti-tank.

And it wasn' t just one chronograph I shot thru. If you read the post, it was several, different ones, owned by different people, at different archery events. But, this is getting ridiculous and taking away from the original question of this thread. Have a nice day. :)

RE: Kenetic energy
 

Danny45,

That bow could reach those claims. The performa cams on a deviator would get a 520 grain arrow close to 285. that would give about 93 to 94 ft-lbs. I believe tha AMO rating was around 253 ( something like that)

Awesome number but a real bear to shoot. A buddy had one. I have to say it was awesome but I couldn' t handle the speed.

RE: Kenetic energy
 

Odd then that my steel-force heads got the LOWEST penetration in my tests (Very repeatable)
In most recent testing, Slick trick was #1 Shockwave #2 Muzzy 3 blade #3 and Steelforce #4
All 100gn heads, shoot on the same arrow/s out of the same bow on the same day. at 270 fps (+/- 3 fps)