Arrow Weight/Speed vs. Penetration
Equipment
I have a bear hunt booked this spring and decided to build some new arrows for it. My deer/elk arrows are 29" Easton A/C/C Prohunter 300 with three helical Blazers and a 100 gr Viper Trick. Total arrow weight is 452 gr. I shoot a 2014 PSE Source 70 lbs and 29" draw. I have a Ripcord Code Red rest on this bow. IBO is 335.
I wanted to build a heavier arrow and ordered a dozen Easton FMJ Dangerous Game arrows. I cut them to 30" and epoxied the 75 gr brass inserts in this morning. Fletched with 3 Blazer vanes and a 125 gr head they should come in at 695 gr.
While waiting for the epoxy to dry, I tried shooting some heavier arrows that I have made up for a high poundage bow that I have. These are 30" Radial X-Weave 400s. With a 125 gr point they weigh 780 grs. I shot several pairs of each arrow at a target set at 30 yards. I rotated the target center so that I was shooting into an unused portion of the the target. I thought I would get much better penetration with the heavier arrows. I was wrong.
To me this means that at some point the slower arrow looses energy to where the KE drops below the lighter, faster arrow. I knew that would happen at some point but I didn't think it would happen at less than 30 yards. Granted, it's a pretty significant weight increase so the FMJ at 695 grs might work out better or maybe my A/C/Cs are the most efficient weight/speed combo of the three. I'll test them when I'm done and see how they do.
Anyone have any similar experiences?
Heavier arrow should maintain kinetic energy better than the lighter faster arrow.
I am certain this is not the norm.
Be right back..... I ran out of popcorn reading the Leatherwall instinctive shooting thread. Need to make some more before this one gets going on the circular road to nowhere.
Either will work for a bear.
A target is not a animal, and that arrow is way overboard for bears.
Your deer/elk arrow should work just fine. You might be overthinking this subject unless you are after grizzs or polar bears. I do believe most bear stands are set up closer than 30 yards, but more like 20-25. If anything, I will go to a larger BH with wider cutting dia. Put your BH through the heart/lungs and you will find your bear at the END of the blood trail.
So I put this in the equipment forum because my experience/question really has to do with performance and not hunting.
Rocky D, I felt the same way but repeated the shots six times and every time I came up with the same result. Like I said, not what I expected.
Wifish, A targets not an animal? Thanks for that, it was really helpful.
Paul, It's a grizzly hunt in the Brooks Range. I agree about blackies and have killed several with my normal set-up. But I wanted to bump up my weight some for a shot at (hopefully) a bigger bear. I know my current setup will kill anything in NA with the right placement, I just thought if I'm building arrows anyway might as well go heavier.
The End, I have a friend that shoots a longbow that is much slower than my compound with arrows that weigh 200+ grs more than my setup. He always gets more penetration and many times gets a pass through on most pigs that we shoot.
This is my experience and several Bowsiters have shot brownies and grizzly so I would ask about setups for the bigger bruins.
P.S. not to be redundant targets are different than animals. When I switched to lighter setup my target penetration was not much different but was substantial on big pigs.
The End, I have a friend that shoots a longbow that is much slower than my compound with arrows that weigh 200+ grs more than my setup. He always gets more penetration and many times gets a pass through on most pigs that we shoot.
This is my experience and several Bowsiters have shot brownies and grizzly so I would ask about setups for the bigger bruins.
P.S. not to be redundant targets are different than animals. When I switched to lighter setup my target penetration was not much different but was substantial on big pigs.
Could be tuning and/or larger diameter shaft causing less penetration. A target isn't an animal means the target stops the arrow with friction so a larger diameter shaft would have more of an impact with a target than an animal. An animal will provide more lubrication to the arrow with blood and tissue so shaft diameter would have less of an impact on penetration especially when you consider the broad head will cut a path for the shaft to glide through and that's not the case with a foam target and field points.
I think a target is a better medium for testing penetration than an animal. When comparing arrow to arrow and you move over to inches from your first shot the density and thickness are the same. In an animal it changes. The diameter on both arrows I shot this morning are approx. that same.
Shaft diameter, finish, the field point size in relation to the shaft size, etc... are all variables that affect penetration in a target that stops by friction. an animal does no stop by friction on the shaft. A target is not a better medium for penetration test unless you are seeing which one penetrates a target better. It is apples to oranges. More importantly, it is a moot point. Get whatever shaft tuned and put it in the vitals. the rest is just preference talk. God Bless men
What does approximately mean? A small amount of diameter difference will affect penetration in man made products like foam.Not so much in game.Shaft finish can also have an affect.At any rate,I chronographed arrows up to 15 grains per pound of bow weight and kinetic energy only increased through all weights.I don't doubt your outcome but believe it is something other than a decrease in kinetic energy.A chronograph would tell you for sure.
"I think a target is a better medium for testing penetration than an animal"
I'm not sure how? Some guys above explained the difference in the target/animal thing. Shoot what makes you happy bud, some guys like heavy, some guys like light.
I'm more of a happy medium guy, no reason to shoot a telephone poll in a rainbow, on this continent. If you want to really test your arrow building/penetration, build a target that at least resembles a critter.
The heavier slower arrow will start with more energy and will lose less energy than a lighter arrow unless something else is different.
KE really isn't a good indicator of potential when comparing projectiles travelling at typical arrow velocities. The momentum equation would yield a more accurate comparison. With that said, the critter test seems to favor the higher mass.
Grizz are also pretty thin skinned, like a black bear. I'll be hunting them in a few weeks with a 460 grain arrow traveling about 280 fps. I'd personally just have confidence in whatever your setup is but don't over think it. Best of luck on your hunt, the Brooks are beautiful.
JimB, By approximately I mean similar. In this case, A/C/Cs have a diameter of .281" and Mambas have a diameter of .295".
Wifish, The reason the target is a better medium is because I was testing for penetration into the TARGET. As I stated, this is in the equipment forum with observations on equipment.
However, to bring animals into the equation, I think it's logical to conclude that the arrow that penetrates further in to a high friction environment (the target) would also penetrate further into a lower friction/ lubricated environment (the animal). Of course, there could be magic involved and I not up on that.
My point is that, for my setup anyway, there seems to be a point of diminishing returns when adding weight. For TARGET penetration the 780 grain Mambas seem to be above that point. When I'm done with my FMJs I'll test them against my A/C/Cs and see how they do.
Nick, Thanks! I'm chomping at the bit here. I'm flying into Fairbanks and meeting up with Stan Parkerson to head up into the mountains on May 14th. I can't wait! Good luck on all your hunts this year!
The END,that's actually a lot of difference when it comes to friction in a man made target medium.I wasn't expecting that much difference.I do believe that man made target material can be used for comparison if the diameters and points are identical but that's hard to do.I wouldn't take your test as a prediction of what will happen on game but believe any of those setups will work for you.Good luck on your hunt.
Good luck, I'll likely see you guys up there.
Which one are you the most consistently accurate with? THAT'S the one you want to use.
And that's assuming that they are both quiet.
I would talk to someone with polar bear "killing" experience before just spending time building arrows. Their knowledge, equipment set up and actual killing experience is invaluable. Several on this site have killed polar bears.
The END, your results are not that unusual.
http://www.youtube.com/watch?v=t4RGcyZ_gJY&feature=youtube_gdata_player
http://www.youtube.com/watch?v=VAfK0sBsZBw&feature=youtube_gdata_player
The END: I killed a griz and a brownie with arrows about the same weight as yours but flying 60 fps slower. Both passed through on broadside shots with 125-grain Muzzies. Good luck on your hunt!
Hey Jaquomo, don't worry buddy I got ya covered!
You said you were shooting a 300 spine with 100 grain points then went to a .400 spine with 125 grain points and a long arrow and a 29"s draw. It may be you are a bit weak on spine with the heavier arrow and poor flight will effect penetration quite a bit. Scooby
To answer this thread simply, two arrows one 100 grains heavier than the other and both with same fletch, same tips and both traveling exactly the same speed, both the same diameter, Which is going to penetrate best? Answer the one with the slickest wax. LOL
God bless, Steve
To answer this thread simply, two arrows one 100 grains heavier than the other and both with same fletch, same tips and both traveling exactly the same speed, both the same diameter, Which is going to penetrate best? Answer the one with the slickest wax. LOL
God bless, Steve
There is an old joke where a scientist measured and recorded the distance of how far a frog could jump. He would like the frog up against a line on the table, clap, and the frog would jump. His first entry was "frog with 4 legs: 30 inches". After each instance, he cut off one of the frog's legs, retested, and recorded the distance. Each time the recorded distance decreased - 3 legs, 2 legs, 1 leg, and then finally no legs. His last journal entry read "frog with no legs: deaf".
There may a point of diminishing returns, but more likely there are factors that you are not accounting for which are resulting in the appearance of diminishing returns: difference in diameter between the shafts, differences in point diameter/differential between point and shaft diameter, differences in friction between the shaft types, and perhaps the lighter arrows being shot into the target closer to the area that had already been shot up, resulting in slightly less compression on the shafts.
I'm going to throw a question into the dissuasion - are we really talking about getting past the potentially bigger bones on larger animals (e.g. ribs). On thin skinned animals (i.e., not a big boar hog with a shield or a cape buffalo), the only thing that is going to substantially slow a modern arrow is bone. We've all seen arrows just zipping through animals - pretty much what i expect when my arrow hits only skin, then innards. A large bone, however, seems like it would stop a lighter (lower momentum) arrow more than a heavier (higher momentum) arrow. I have no scientific basis for this theory, but having seen an elk rib do a pretty good job of stopping (in about 8 inches) an arrow shot from less than 15 yards, I for one am going to a heavier arrow next fall.
It seems to me the oringinal poster was looking for confirmation of his opinion.
Looks like you hit leg bone with the two lower arrows.
Your 450 gr deer/elk arrows would be fine and would be what I'd take on the grizzly hunt. The bears up in the Brooks Range are not giants, and even if they were, I'd take the 450 grain arrows assuming they tune and fly well from your rig.
Your 790 gr 400s are probably severely underspined for your set up. Don't know about your ACCs or FMJ, but ensure they are matched to your bow, draw length, point weight, etc. As a side note, the foam deer target vital insert looks like it is shot up a bit more in the vitals as well as having a white core of different density foam. The lower leg area where penetration was less appears to be on the perimeter of the insert, maybe without the dual density composite foam? You need a virgin target that is 100% the same foam throughout to compare penetration of each arrow in that material.
I have shot a BC grizzly with a 375 gr arrow/Ulmer Edge expandable and an Alaskan brown bear with a 475 gr arrow/3-blade Rocky Mt Iron Head. No penetration issues in either case and used "slow" Mathews 29" draw Solo Cam bows.......a 65# Drenalin and a 62# Creed respectively as a matter of perspective.
Good luck on your Brooks grizzly bear hunt! It will be an adventure no matter what gear you take.
Fu, you win!
Now bring some PBR and you'll break the internet!
Either setup is fine.
The bigger question is what caliber is the backup gun?
I would focus more on arrow flight in the wind than using an ultra heavy arrow for your hunt. 450-550gr is more than enough arrow....
I've always believed a thinner shaft penetrates further. ;) seriously though I've never shot thin arrows but I know my nephews thin arrows out penetrate standard arrows of the same weight even though he's pulling less poundage. The difference in diameter in 2.95-2.81 is roughly 5%, I'm not smart enough to figure surface area.;) Without shafts of the same size, percent foc I think this "test" isn't worth much.
You can't judge how an arrow will perform on an animal in a dry target designed to stop all manner of arrows safely- period! There's a wealth of knowledge by guys that have shot just about every animal imaginable on here, ask them what they used. There's no medium out there for targets that can account for all the possible penetration scenarios you can come up with on just one animal. Trust physics and go with what's worked for others!
Brown bear taken at 8 yards with a "skinny" shaft tipped with a mech head, weighing around 460 grains out of a 60lb Bow. He made it 35 yards and was dead in less than 15 seconds.
the faster arrow "melts" the foam at a different rate and amount. Which can either increase or decrease penetration, depending on type of foam. Foam targets are not a good indicator of penetration.
Probably not as much difference as you think. Take the total surface area of each arrow inside the foam. Not just the length, but the total surface area. Get out your Geometry workbook ;)
Friction has NOTHING to do with area. It is only dependent upon the coefficient of friction of the materials and the force perpendicular to the materials.
The angle of the dangle ..........
Heavier is ALWAYS better, except for women.
Rutnstrut, no BBW love. You say that till your in a tent with temps hovering around zero and your in a bag that is for summer camping trips.
Fulldraw, A buddy of mine had a saying. She ain't a lady if she ain't 280;)
In my experience. A little extra weight equals dependable results. Lighter weight often resulted in unpredictable behavior.
Glunt, you talkin' women or arrows? Um, nevermind...pretty much goes for both.
Here we go again... Don't say anything about the long thread on the Leatherwall. This light/heavy arrow debate is old and worn out. Too light arrows are bad for your bow. It ain't about speed but then again typical compound mentality.
Red, did you get your panty's twisted up reading the LW thread?
All things being equal, FMJ's will always out penetrate a standard Carbon or any carbon for that matter in a target situation based on one thing: finish. An FMJ is extremely smooth surfaced and easy to remove from targets because of the low surface friction. This is also a curse because I shoot through a lot of 3D targets once they have taken some shots. It's an imperfect way to measure penetration.
We should all consider ourselves lucky that the guys who know what bowhunting is and "ain't about" are willing to clue the rest of us in on it....
"Friction has NOTHING to do with area. It is only dependent upon the coefficient of friction of the materials and the force perpendicular to the materials."
So, you're saying that a 1/2" diameter arrow will penetrate foam just as far as a 1/4" diameter arrow, all else being equal?
Interesting reading always on this subject. I have been shooting 400 grain arrows(whitetails are all I hunt) for years and have no problems except when offside shoulder is hit. Trying some 460 grain arrows now and they are a little quieter but not seeing the same accuracy. They are a move up in spine from 340 to 300 but my 340s are borderline light. Still planning on testing but my initial results were not that much of a difference. Maybe need a really heavy shaft like 550 plus? But for deer I think it's overkill. Thoughts? Oh I ran the numbers and my KE went up 2lbs and momentum went up 0.05 with the heavier shaft. Not sure it's significant for deer
No, I didn't say that at all. I said area has NOTHING to do with friction.
Since nobody really shoots much over 40 yards I would just build an arrow that could hit the vitals of a deer from any angle and be done with it.
"No, I didn't say that at all. I said area has NOTHING to do with friction."
Same thing. If (according to you) the amount of surface area per inch of arrow shaft length of "arrow A" is 3 square inches, and the amount of surface area per inch of arrow shaft of "arrow B" is 2 square inches, both being the same weight, and shot from the same bow, ...you are saying they will penetrate the same.
"surface area per square inch of arrow length" ...... LOL
You are hopeless. I'll let someone else waste their time bringing you up to speed.
Bla bla bla, the more surface area per inch of shaft the less it will penetrate, all else being equal.
Nobody said anything about per square inches of arrow length. Everyone here knows what xman is saying, with the exception of you.
Looks like we have 2 people lost in the gigly weeds. Anyone want to help these guys out?
I'll give you a hint.......google.
You could just enlighten us with your wisdom instead.
In a medium designed to close back up and create friction it only makes sense (in my little brain) that a faster arrow would penetrate farther as the medium reacts.
Tradmt I'm beginning to think he can't explain his logic or physics whichever he is using.
Hey, I don't claim to be the smartest guy around and if I am wrong then just tell me why and how. To me it just looked like Purdue misread what was typed and then tried making xman look stupid.
It sure seems to me that the greater surface area of arrow shaft to be acted upon by the target foam would have an effect on how far it penetrates.
It makes sense to me that a 2" diameter arrow (if there was one) would not penetrate as well as one with a 1/4 diameter into foam when weight and velocity is the same. So there must be a measurable difference in .295 and .281.
I stole his girlfriend in the fifth grade. He'd been out to get me ever since. :)
Question Why doesn't friction depend on surface area?
Answer Although a larger area of contact between two surfaces would create a larger source of frictional forces, it also reduces the pressure between the two surfaces for a given force holding them together. Since pressure equals force divided by the area of contact, it works out that the increase in friction generating area is exactly offset by the reduction in pressure; the resulting frictional forces, then, are dependent only on the frictional coefficient of the materials and the FORCE holding them together.
If you were to increase the force as you increased the area to keep PRESSURE the same, then increasing the area WOULD increase the frictional force between the two surfaces.
I think the smaller, lighter faster shafts generate more heat and slightly melt the target medium and lubricate the arrow increasing penetration, just a hunch of what's going on based on the target medium that you find stuck to the arrow when you pull them out of the target.
Foam has to compress to make room for the arrow. It wants to return to it's original shape. It's basically pushing against the surface of the arrow. The bigger the object you want to push through it, the more resistance you will get as you compress more foam.
Stuck with my deer/elk setup on a brownie hunt on the peninsular a couple years ago. 462 total weight. FMJ with 100 grain slick trick. 35 five yards and it was over in under a minute.
I'm not trying to be coy. It's just that I've learned that most here don't believe anything I say. It takes more than facts to convince them, so why waste my time. When I taught at Purdue I was compensated for my time. Why should I give it away here, especially to people unwilling to learn. Those types will only learn if they figure it out on their own. Unfortunately they are usually also the type that are unwilling to do a little research .... intellectually lazy. Most of the above comments illustrates my point. People just want to be hand fed the answer. They are still trying to fit "area" into the explanation. Carry on.
Which is a fancy way of saying he doesn't understand it either.
I don't teach at Purdue and graduated with a lowly business degree but it seems logical to me that the larger diameter shaft would result in an increase of pressure due to the closed cell foam medium thus increasing friction and reducing penetration.
In the real world, physic's doesn't always accurately account for what happens. A physicist would tell you that area has no merits in the discussion. Because the law of physics says so. Good ole boy intellect will tell you the physicist is giving credit for increased friction to something besides the obvious variable of area. Which cause the good ole boy to shake his head and wander why things are made so hard by "science". I'm a good ole boy. Stupid? Maybe. Ignorant? Nope. I mean no disrespect but, I really could care less what Purdue or physics say about this other than I KNOW in the real world, all things else being equal, a smaller diameter arrow will out penetrate a larger diameter arrow in a target that stops by friction.
God Bless men
If following such logic, that faster (less weight) is the route to penetration..... cape buff hunters have it all wrong..... instead of building a heavier arrow which makes for slower FPS..... obviously according to foam, they should be building ULTRA lite arrows from high lb bows and shooting for over 400-450 FPS to blow through those big ol bovines......
I'm thinkin' a mech head for good flight and a big ol cut for good measure too......
Im not a rocket scientists either but it would seam to me that on a foam target that exerts 30 psi the much larger shaft would force foam outwards compressing it and increasing the pressure exerted by the foam. No?
"Which is a fancy way of saying he doesn't understand it either."
Must still be searching Youtube for the answer.
So if I am a custodian at Harvard, and I teach the "new guy" how to clean, can I tell people that I "taught" at Harvard?
Not sure what term the custodian would use, but I will say when it comes to a common sense physics issue like whether a tack hammer or a sledge hammer is better for busting concrete, he's probably a better source than the professor. The professor would get the answer, but the concrete needed to be smashed this afternoon, not after a grant proposal, white paper and peer reviewed publishing happens.
Tests on dogs and cats have conclusively proved that the only relevant item is fletching color
Tiz I may not be a rocket scientist, but wouldn't a fatter arrow cause greater displacement (which a target is trying to heal) and therefore bring more or at least equal pressure to bear per given amount of arrow area. If the same area on two different arrows has the same coefficient of friction, but one has greater area, that one is going to experience more frictional force - yes? Maybe the ol' professor can mansplain it to us (maybe not). As for me, I'll harken back to an early physics lesson: lubing the shaft = better penetration.
William Tell that would have been a physique lesson I think!
"Always lube your shaft" .... depends on your target
Live flesh is far different than foam or even ballistic gel. Flesh reacts to damage by pulling away from a wound. When the razor sharp edge of the broad head slashes skin and flesh, the skin will separate and the wound will open up. There is far less pressure back on the shaft of the arrow to slow it down and bodily fluids become a lubricant where the shaft does make contact. The majority of energy required is to push the blades through to cut tissue. Hence, razor sharp broad heads along with good shot placement to avoid bone carries more importance than speed, weight or kinetic energy.
I don't see any down side to thinner arrows but I agree it's probably not a big factor on game. I use to shoot 23/64 wood shafts that are over twice the diameter of FMJ Deep Six shafts. They screamed along at a whopping 160fps but generally passed all the way through game.
The last several posts pretty much summed up a current PM conversation. Though I agree penetration in foam may be significant while penetration in flesh may be insignificant, there are and will always be errant shots or misdirected arrows..etc.. that will contact bigger bones. I'd like to have as much energy possible when those moments happen.
Furthermore, thinner arrows of same weight deflect more wind. Not an issue when 98% of your shots are 20yds or less from a tree, but something to consider when you're launching arrows 60yds at an antelope. The wind gusts out here in NM are called tornadoes back in OH. For hunting, thin wins; for targets, fatties cut the line.
Turkey season starts in 2 less then 2 weeks here. No lube required.
