Speed, or Weight
 

For years I hunted with a heavy, slower arrow. It seemed as though I had many pass through shots with this set up. In the past couple years I have been shooting lighter, and faster arrows. I have killed 2 elk, and 1 javelina with this set up without a pass through.

Just a coincidence? I know every shot is unique and many factors contribute to ultimate arrow penetration, but I have been wondering if heavy is better.

To confuse me even more, I have more kinetic energy leaving the bow with my lighter set up.

What have you noticed with pass thru shots?

Dan

RE: Speed, or Weight
 

I' m curious to know your setups that your getting less KE with the heavier arrow. If nothing else changes, bow poundage, draw length on the bow, your KE should stay relatively the same and I' d surmise it' d gain with the heavier arrow.

RE: Speed, or Weight
 

What were your heads then and now?

RE: Speed, or Weight
 

Rob,

They heavier set up was on an older, slower bow.

Dan

RE: Speed, or Weight
 

Nub:

Broadheads did change. Then: 125 gr Rocky Mtns Now: 100 grain Thunderheads.

RE: Speed, or Weight
 

Either you aren' t hitting the right spot/s, or your new heads are not as good as the old heads.
More KE AND more speed will give you better penetration when shooting the same spot.
If your hits aren' t " right" you can' t blame the rig.
IF the shots are good, you are just getting a touch of bad luck. Not EVERY shot will go right through.

RE: Speed, or Weight
 

There' s the answer to your KE question. The reason you' re getting more KE out of the light, fast setup is you changed to a higher performance bow! If you' d put the heavy arrows on the new bow, they would most likely get a bit more KE than the lighter arrows.

As for the lack of penetration, I' m one of the few heretics on the site that firmly believes in heavier arrows for hunting - especially for bigger stuff like elk. I' ve been arguing with these guys over light vs heavy arrows and penetration for the past several years, and the archives are full of those threads.

If you' ve gone two years without a passthru, then I' d say you' ve done a pretty good field test on your light arrow setup and maybe you should start thinking about adding some weight to your arrows.

RE: Speed, or Weight
 

Now you see the light. Heavy usually passes through, light arrows usually
don' t. At least this is what I have discovered over the years.

RE: Speed, or Weight
 

Now wait a second. Arthur posted a good two-three paragraph reply and I did not see the word " momentum" mentioned once.

You feeling ok Art?

:D

I agree with Arthur. The lighter arrows might not be carrying as much momentum though they might have more KE when comparing your old bow setup with your new one. As Arthur stated I would like to see what you can do with the heavier arrows on your new bow.

Or better yet, go with medium weight arrows and get the best of both worlds. ;)

RE: Speed, or Weight
 

What I have noticed. Light set up generating 60 foot lbs of KE. At 14 yards will get a pass through with a heart shot. Same set up at 28 yards another heart shot, no pass through.
What you all forget when you talk about pass throughs and kinetic energy is how much friction the arrow is trying to pass through. The heart of the deer had enough friction to stop the arrow at 28 yards but not at 14.
now if you don' t hit the heart, just lungs at 28 yards it will most likey pass through.

If you hit any shoulder bones at any range no pass throughs. Just a couple of things I have noticed with some of my setups....

I would sumise when shooting an elk I would go with slow and heavier as I would want the momemetum and extra down range energy because the elk is bigger and wider than a deer and presents more friction to the arrow as it tries to pass through.. I don' t see why you all don' t get it yet......[:@] Slower and heavier is better especially on larger animals....... Gee' s end of though end of disuccision..
not going to reply to anyone on this....

RE: Speed, or Weight
 

Yep. Just didn' t feel like reopening that can of worms. Plenty of discussion about that in the archives and the myth of speed and KE is too firmly intrenched to be overcome now. It' s only when a lot more people start seeing results like Dan has that they will start waking up to reality. SOME people can use light arrows, 5-6 grains per pound, at high speeds and do well. I think most people would do much better to set 7 grains per pound as a minimum for a hunting arrow.

The way I see things, the lower your draw weight -and/or- the shorter your draw length -and/or- the less efficient your bow is, the higher your arrow weight to draw weight ratio should be. Especially, as Bees so eloquently pointed out :), when you' re after a large or thick skinned critter.

I have to admit to hunting with arrows at 6 grains per pound back in the 80' s. And I was using them with a longbow, of all things. However, the arrows were 720 grains. ;)

RE: Speed, or Weight
 

Good point...and you elaborated on it very well with your next statement....

....and if you put both of those statements together into an example it would be something like...

...Bubba shooting a Bowtech Pro 40 at a 30 inch draw length and a 70 lb draw weight can probably get away with shooting a 375-425 grain arrow and still expect very good KE and penetration in general on just about anything he would normally shoot. While on the other hand, his cousin, T-bone, might not get very good performance in terms of KE or penetration if he is shooting a PSE Nova with Vector wheels set at 50 lbs with a 27 inch draw length and an arrow weighing in around 250- 300 grains. Right?

Same 5-6 grains per pound ratio but the bow, draw length and draw weight all factor into it.

Excellent post Arthur.

RE: Speed, or Weight
 

Arthur and PA:

Thanks for the helpful feedback. Can you go into more detail on momentum vs KE?

Additionally, I don' t think T-Bone has a very good set up for elk.

RE: Speed, or Weight
 

The KE vs. Momentum vs. Speed debate will never be agreed upon as long as we all shal live.
You can find 100 guys that will tell you FROM EXPERIANCE that lighter is better, and they get nothing but pass throughs on Moose with 50gn mech heads, and you can get another 100 that will tell you the only way to get a pass through on anything bigger than a balloon is to go with 1000gn arrows flying at 100fps...they will tell you this from experiance.
You can also find several semi-scientific tests showing that heavy and slow is better...and light and fast is better....and still other tests that say it' s all the same.
The best tests I have read, and my own tests have shown ME, that it pretty much IS all the same...within reason.
1 thing I have found that is reasonably constant. the slower the arrow, the better to have a cut on impact head. The faster the head, the better you are with a head that has less surface area (Slick Tricks...and similar...and even mech heads).
Match your head to your arrow, and you' ll do fine.

RE: Speed, or Weight
 

Dan,

Explaining momentum is more of Arthur' s cup of tea than mine. As with most equipment related issues I always take the road of " moderation" . I realize that both KE and momentum play a large part in penetration but do not place excessive stock in either. I prefer to have enough of both so that my setup can be sufficient for either side of the argument.

For example, my arrows are roughly 6-6.5 grains per pound of my draw weight. This provides reasonably flat trajectory, very good speed (considering my draw length and draw weight) and yet at the same time I have enough mass weight to satisfy those who prefer to use momentum as the primary indicator of penetration.

In essence, I believe you need a healthy dose of both to cover all of your bases. :)

RE: Speed, or Weight
 

With a 70 pound hard cam compound and 30" draw with a 350 grain arrow, the fabled ' IBO standard' , shooting 300 fps, you get 70 ft lbs of energy and .4655 lb secs of momentum. That arrow will pass through a deer on a good broadside hit, according to all reports. I would not shoot such a rig at an animal, so I wouldn' t know from my experience.

What I do know is that my 580 grain arrows from a longbow at 182 fps gives me 42 ft lbs of energy, exactly the same momentum as the light arrow, .4655 lb secs, and will pass through a deer on a good broadside hit using Magnus heads. It will also pass through feral hogs in the 300-350 pound class. Using blunts, it will flat knock the stuffings out of rabbits and squirrels with a solid thump on the noggin.

Now, this raises a problem for those that claim KE is the best determinant of how much penetration you get. I get the same passthru as the high KE bow does with 28 ft lbs LESS energy. The common factor between the two setups is momentum. Of course, when confronted with that problem the KE crowd ignores it. :)

Like I said above, the lower KE your bow gives you (lighter draw weights, shorter draw lengths, less efficient bow designs), the higher your arrow weight to draw weight ratio should be. That is because you have to rely more on momentum when you don' t get gobs of KE.

RE: Speed, or Weight
 

Arthur, how does one go about calculating momentum?

RE: Speed, or Weight
 

One goes over to Jackson' s site and plugs his numbers into the ballistics program. :D

At least, that' s how I do it. I used to know the formula but when I found that program, I promptly forgot it. The good thing about the ballistics program is you can also see what kind of performance you can expect downrange, where the animal is. Also, there' s a link to a graphing trajectory calculator so you can see what various arrow weights and speeds do to your trajectory. Great stuff!

www.bowjackson.com

RE: Speed, or Weight
 

Wow, I was just telling my youngest daughter this a.m. that you learn something new everyday if you pay attention, and I' ll be damned...

As many times as I' ve been on the site, I' ve never been to that part. Thanks for the kick in the seat :)

RE: Speed, or Weight
 

Despite the risk in sounding like I am firmly in the KE crowd...

...Yeah, but Arthur, that 180 fps arrow will arc more than a rainbow.

:D

Sorry, had to say it. :)

Seriously though, I guess that we could say that many of our current equipment beliefs are based one upon the other....and this KE/momentum issue is a perfect example....

....in order to flatten our trajectories to somewhat compensate for poor yardage estimation skills the bowhunting fraternity had turned their heads towards faster arrows. Those faster arrows are primarily obtained by lightening their overall weight. Since we lightened the overall weight of the arrows we also greatly decreased the momentum that each arrow carries with it. So, in order to justify our choice of light arrows and their ability to continue to penetrate well with certain setups we have turned to using KE as a basis for comparison.

Would that be somewhat along your line of thinking Arthur?

RE: Speed, or Weight
 

True, but I bet his bow is so quiet that the animal won' t even flinch in the 5 seconds that it takes his arrow to travel 20 yds.;)

RE: Speed, or Weight
 

Jeep ;either that or the deer is over it and started feeding again [8D] seriously though heaveyer arrows just work better for hunting especialy for short draw low pound shooters and , two blade cut on contacts penetrate better allso . Remember if you have to track an animal 2 holes are better that one or better than one thats got an arrow pluging it .

RE: Speed, or Weight
 

Actually, Frank, they do. However that' s only a problem for someone that is enslaved by the sights on their bow. Those of us that are free from artificial aiming devices don' t even notice it.


That' s an expansive version of exactly what I thought I said. :)

I don' t remember ever hearing anything about KE pertaining to archery at all until ICS carbons and overbuilt/overpriced bows. Overbuilt to keep them from blowing up in your face at 5 grains per pound.

RE: Speed, or Weight
 

Speed v Weight,Why can' t you have both?I know I do.......Mathews LX,30in.67lbs,Beaman Carbon-Hunters 380' s cut at 28.5,85gr Shockwaves,3in. Duravanes,413grs total weight....277fps,70lbs KE.Flat shooting,deadly,and accurate to 50yds.Whats not to like?...Bob

RE: Speed, or Weight
 

Momentum = mass x velocity
arrow weight/7000 = weight in lbs
lbs/32.414 = Mass
:divide by 32.414 for gravity
Mass x Velocity = Momentum

580Grains/7000 = .082857
.082857/32.414 = .002556
.002556 x 182 = .46523 lb secs

There you go now have fun.

RE: Speed, or Weight
 

Just my two cents. I have had complete passthroughs as well with an old bow, shooting heavy aluminum arrows. I know shoot a new bow with significantly lighters arrows and still get complete passthroughs. There was a thread here recently discussing how the newer bows are getting more efficient at transfering energy to the arrow instead of wasting it through the bow with a light arrow setup. This leads me to believe that you should be getting roughly the same KE out of a new bow-light arrow setup.

I do however agree that a little heavier arrow is a better bet for hunting. I try to fall in the middle weight, somewhere in the neighborhood of 380-400 grains. I get good speed, and great penetration. My last seven deer have been all passthroughs with this setup including a quartering shot that broke the front leg on exit.

Just my thoughts.

RE: Speed, or Weight
 

Arthur,

I have no doubt that those of us who are not technologically impaired are capable of putting together some impressive groups through instinctive shooting. However, the amount of time needed to become affective in that method is very prohibitive to the average archer/bowhunter today. But for you retired folks.....

:D

Sorry for being too long-winded on my reiteration of your explanation. Sometimes I just need to put it into my own words to understand the concept thoroughly.

So, basically, the craze for speed is to blame for many of current archery shortcomings....;)

RE: Speed, or Weight
 

Frank, just wondering... When was the last time you shot a compound without sights for any length of time? Like a month or two?

Mahly, when they start making deer out of ethafoam and styrofoam, that' s when I' ll start paying attention to these stupid ' tests' that use that stuff as a test medium. As long as critters are made from hide, meat, fat, bones and organs, I' ll stay with my big ol' arrows.

How many guys do you see shooting light carbon arrows for bowfishing? Not too many? Most are using those 1,000 grain solid fiberglass jobs to penetrate deep in the water. Since animal flesh is about 70% water....

RE: Speed, or Weight
 

Alright. For the sake of keeping this debate SOMEWHAT scientific (pass through count on deer is NOT scientific proof...WAY too many variables head type, sharpness, shot location, size of deer, ribs hit etc)
Here is a test done showing arrow penetration in 2 consistant forms of media. Though the media is NOT consistant with deer... the test is to simply show the results of KE vs. speed. Anyone wanting to argue momentum, can post the momentum figures for each arrow (I dare ya ;) )

Look at the following chart:



Arrow #1 while having slightly LESS KE (and a LOT less momentum) actually went SLIGHTLY farther than arrow#2 in both cases.

ALL this test measures is the difference between a lighter faster arrow, and a heavier/slower one, with almost identical KE.

You MAY find a test elswhere that says differently, but this test DOES seem to change only one variable at a time (different wieght arrows with the same KE...OK maybe to things speed and momentum' s impact on penetration)

This test also is limited to the 2 arrows going at 53 KE whether or not higher or lower KE numbers are equally effected remains to be posted. but one thing IS clear. You can NOT accuratly say " momentum is the most important thing in penetration" Momentum was up and down in this test...and didn' t make a noticable differance at all.

BTW....for those interested arrow #1 has about .434lb-sec momentum, and arrow #2 has .534lb-sec momentum which is about 23% more momentum...for ZERO gain.

RE: Speed, or Weight
 

Gonna start useing carp tips and fiberglass arrows to get better pass throughs?;)
Bow fishing is a bit different...you are now fighting gravity as much as penetration. (Most arrows float)
Granted, deer are not made of foam....but penetration is penetration. you can' t change 3-4 things in a test and hope to come up with solid answers.
The tests simply show, that in a constant media...momentum is not as effective at estimating penetration as KE is.
Now, if you can get me 20-30 identical twin deer...that have all eaten the same, and are in every way imaginable identical...and we can put arrows in the exact same spot on each one when they are all holding the same amount of air in their lungs...and the last one isn' t too freaked out after seeing the first 19-29 of his brothers getting shot...THEN we can test it YOUR way...until then we are limited to synthetic matterial that is easy to make consistant to do scientific tests.

RE: Speed, or Weight
 

These tests in synthetic materials is like doing a test to see which of a pair of cars gets better gas mileage but filling them up with diesel instead of gas.

Even assuming we can accept results in foam and crap like that, this ' test' stinks. What about the test neglecting to say anything about arrow diameter? Was the heavy arrow a 2419 and the light one a skinny pultruded carbon? What about surface finish? Were both arrows the same material or different? If you are going to have a scientific test, you need to eliminate as many variables as possible.

RE: Speed, or Weight
 

Arthur, I see your point, but don' t the arrows you are using in real world conditions have the variables you mentioned yet still reportedly penetrate better? If so, that doesn' t seem to point to the variables having much of an impact on the testing above...

I know when shooting at the big plastic bale targets at our local range, my 350 grain ACCs consistently out penetrate the 500 grain CE Terminator hunters, and make a much louder " WHAP" when impacting the target. Granted the ACCs are thinner than the CE, but still the difference is not negligible...

RE: Speed, or Weight
 

What is the primary focus of the test? To see whether KE or momentum best determines penetration. To test that, you have to have shafts and points that are identical in ALL respects, except for weight. Then your test medium. Your test will tell you which does best in a certain medium, but will the results be the same in a different one? Say you switch from foam to wet sand, will the results be the same?

Smaller diameter arrows penetrate better than large diameter in targets that are designed to stop arrows by friction. Smaller diameter, less surface area. Less surface area, less friction. Less friction, more penetration. Same goes for bag targets that stop arrows by compacting in front of the point. Smaller diameter has less frontal area and packs less material in front of it than the larger diameter arrow, and so penetrates deeper. If the 600 grain arrow was a 2419 and the 400 grainer was pultruded carbon, then you' re comparing apples to oranges. That' s exactly what a lot of these so-called ' tests' have done to ' prove' KE is top dog.

Well, a deer is not designed to stop an arrow by friction. It is not designed to stop an arrow by compaction. It is not designed to stop an arrow at all. So, how can penetration in materials that ARE designed to stop an arrow really correlate to what you can expect in the woods?

The fact of the matter is, heavy arrows have worked just fine for at least 65,000 years with bows yielding relatively low KE figures. And, like I' ve been saying, it' s when you' re dealing with low KE that momentum becomes a lot more important.

RE: Speed, or Weight
 

Arthur,

Admittedly, it has been some time since I shot a compound without the aid of some form of sighting device. I will conceed though that it is not as hard as some people think. I could probably take the sights off of any of my compounds right now and still be able to put together an 8-10 inch group at 20 yards. Now that is not what I would consider acceptable but with some intense practice I am sure that I could get that group size down to under 6 inches.

However, one would also have to consider that by doing what I mentioned above they are then somewhat reducing the distance that they are relatively effective at harvesting game. Sure, I would hazard a guess to say that with even more practice I could probably get those same 6 inch groups at 25 or even 30 yards but then we fall into the trap of what I mentioned earlier.

More practice is needed to shoot instinctively...compound or traditional....and the average bowhunter/archer does not necessarily have that time to devote to it.

RE: Speed, or Weight
 

Frank, I' d be willing to bet you' d group a darn sight better than 10" at 20 yards after about a half hour of figuring out where to hold, using a gap system for aiming. Once you start shooting down the middle, all the rest is just elevation. Once you' ve figured out your gaps, using the tip of the arrow for aiming reference. I can teach you a gap system that uses parts of the arrow rest and the bow' s shelf as additional elevation references. It gives you a sight system like no other. You have no sights, but you' ve got at least 20 different elevation references you can use from point blank out to 100 yards and more. You got 20 pins on your sight bar? :)

Speed is nice, but knowledge and skill are far better tools.

RE: Speed, or Weight
 

All I can add is I' ve blown through elk shooting a 355 gr. arrow going 301 and blown through them shooting a 550 gr arrow going 230ish.

RE: Speed, or Weight
 

Art, what if the test was done with ballistic gelatin, identical arrows only one filled with something that adds the required weight, and then repeated as above?

Would that be a more accurate test?

I' d really be interested in seeing something like this. Perhaps Bowhunting World or some other mag would do it if asked. I think it' d be a very beneficial read...

Let' s design the test parameters EXACTLY and I' ll contact them or others to see if they have any interest in doing it. I know a guy that writes for several of the top bowhunting mags, his pic is even featured in a new Mathews ad... He might be all over something like this.

RE: Speed, or Weight
 

I' d like to see those test done at bowhunting range , say 20 yards , as I would supose that lighter arrows lose their penitrateing qualities faster than heavyer arrows , or heavyer arrows hold their penitrateing qualities better at distance .

RE: Speed, or Weight
 

Again, you can only change 1 thing at a time. If you want to see what KE does vs. momentum, you want the chronograph very close to the target.
Though I' ll have to dig the magazine out to find the specifics, if memory serves me, the arrows were the same diameter...and I believe they were both aluminum. one just had a thicker wall (2216 vs 2219....that kind of thing.)
I would also say that 16 yards IS hunting range. A great deal of animals are harvested inside of 20 yards.
While ethafoam may have been designed to stop arrows...styrofoam was not...it just happens to do an OK job at it...and most importantly...styrofoam can be made consistant enough for repeatable results.
Ballistic gelatin would be nice...but that stuff is a little more expensive, and you MUST control variables such as temperature MUCH more closely.

RE: Speed, or Weight
 

Ballistic gelatin IS expensive and does have to be used under very controlled conditions. Like scientific tests are supposed to be conducted, as a matter of fact. :)

I have an idea for a penetration test based on one I saw a gun writer do once. He built a trough that was open at the ends and just wide enough to hold 1 gallon freezer bags filled with water. He stacked a bunch in the trough, shot through the bags, and measured the distance the bullets penetrated. Seems to me the least costly way to go about it, and since animal flesh IS 70% water, and since water is a lot more consistent in density than any manufacturered product....

Problem is that I can' t perform the test. I' m too prejudiced by my posts on this subject and any data I come up with would be questioned immediately.