Post by: Todd_ID on May 12, 2009, 08:01:11 AM
So here's the results of this morning's testing (playing). I shot these results using 125 grain and 300 grain field points on a FOB-steered .300 spine Easton Axis Arrow at 29" with a Mathews Switchback (2004) at 72# and 30" draw length (advertised IBO speed of 318 FPS).
The .300 spine Axis arrows seemed to be stiff enough to be able to shoot that massive head, and they are also the right spine for the 125 grain broadheads I've been using. The Tissue Penetration Index (TPI) is the end goal according to Dr. Ashby's work; his TPI findings are at the bottom.
The results are:
Magnus Snuffer SS 125 grain 3 Blade
1.44" cutting length
1.0625" cutting diameter
.9035 Mechanical Advantage (MA)
11% FOC balance
487 grain mass weight
269 FPS speed
78.235 foot pounds KE
.582 slug-feet momentum
Final TPI of .526
20-30 yard drop: 5.5"
20-40 yard drop: 12"
Grizzly El Grande 190 grain 2 Blade with 100 grain adapter
3.125" cutting length
1.1875" cutting diameter
2.6316 MA
22% FOC balance
658 grain mass weight
236 FPS speed
81.361 KE
.690 momentum
TPI 1.814
20-30 yard drop: 7"
20-40 yard drop: 20"
Formulas:
KineticEnergy=Weight*Velocity*Velocity /450436
Momentum = Weight * Velocity / 225218
Mechanical Advantage = Length cutting edge/(cut diameter*.5) * number of blades)
TissuePenetrationIndex=Momentum*MA*ShaftDragFactor
Shaft drag factor for both arrows was 1.0 because Axis diameter was less than broadhead ferrule
TPI findings from Dr. Ashby's research
TPI of 0.62 unable to ever penetrate
TPI of 1.27 penetrated scapula +5-8" flesh
TPI of 1.50 penetrated scapula and broke offside ribs on pass-through every time
The end result is that the big, heavy broadhead is 3.5 times better at penetration and bone breaking than a standard 125 grain head. I think I may have found my new setup for big game. I hope to test it out on a bear soon!
Post by: boneaddict on May 12, 2009, 08:08:14 AM
Post by: Todd_ID on May 12, 2009, 08:20:54 AM
Post by: Ray on May 12, 2009, 08:31:24 AM
?
(https://hunting-washington.com/smf/proxy.php?request=http%3A%2F%2Fwww.3riversarchery.com%2Fimages%2Flarge%2F4226X.jpg&hash=34af6b30fbbb93e2514a4adc7b7967782f6e0219)
Post by: bucklucky on May 12, 2009, 08:32:25 AM
Post by: bucklucky on May 12, 2009, 08:33:56 AM
Post by: boneaddict on May 12, 2009, 08:48:23 AM
Post by: boneaddict on May 12, 2009, 08:48:59 AM
Post by: Todd_ID on May 12, 2009, 08:49:42 AM
What is an 100 grain adapter? Is that an insert near the tip or something attached to the broadhead itself?
?
(https://hunting-washington.com/smf/proxy.php?request=http%3A%2F%2Fwww.3riversarchery.com%2Fimages%2Flarge%2F4226X.jpg&hash=34af6b30fbbb93e2514a4adc7b7967782f6e0219)
Yep, that's exactly what it is. It brings us compound guys up to the level of using the traditional guys' equipment.
Post by: Todd_ID on May 12, 2009, 08:51:36 AM
single bevel broadheads are sure the hype.
There're lots of good reasons for that! Dr. Ashby's research on them was fantastic; basically it was solid enough logic and physics that I switched to them.
Post by: bucklucky on May 12, 2009, 08:52:29 AM
single bevel broadheads are sure the hype.
Whats that?
Post by: Todd_ID on May 12, 2009, 09:03:37 AM
Think of the cheap steak knives we all have at home; the ones with seration on one side and flat on the other. Try cutting a slice of cheese off a thick block. You pretty much can't cut straight! This is because the angle of the blade is causing the knife to turn. The knife that is sharpened from both sides will cut straight every time: the same is true of broadheads. When you put that single-bevel on both sides of the broadhead, then the head will rotate as it cuts. This rotation will cause bone to split and break instead of simply trying to cut through it (double-bevel heads have to push/cut through bone). Once the bone breaks, then there is very little resistance left, and the arrow can continue on through the animal.
The next thing is that since the broadhead continues rotating as it travels through the animal this creates an L shaped wound channel instead of an I shape that a double bevel head makes. The tissue/vessels/skin twist onto the head as the are being cut creating much more damage than a standard double-bevel head.
Post by: Ray on May 12, 2009, 09:07:28 AM
(https://hunting-washington.com/smf/proxy.php?request=http%3A%2F%2Fwww.alaskabowhunting.com%2FAssets%2Fimages%2FProduct_Photos%2Fmedium%2FAshby_Broadhead_M.jpg&hash=5b669d30df632243953b9a6b13477af28a18a571)
Post by: bucklucky on May 12, 2009, 09:07:58 AM
Post by: WDFW-SUX on May 12, 2009, 09:09:55 AM
Post by: Ray on May 12, 2009, 09:11:11 AM
I have read it but I have not drank the kool aid yet. :chuckle:
Post by: Machias on May 12, 2009, 09:12:05 AM
How are those single bevel heads to sharpen? I imagine they would be much easier??
Thanks!
Post by: Todd_ID on May 12, 2009, 09:13:06 AM
These are the high-end models.
http://www.braveheartarchery.us/new_page_2.htm
These are the guys that I bought my stuff from. I coudn't spring for the $80/3 broadheads, so I went with the next best option. I got the 190 grain El Grande Grizzly heads.
Post by: Todd_ID on May 12, 2009, 09:19:26 AM
I got some 300 spine ACC pro hunters and 100gr silver flames.........they seem pretty lethal :dunno:
And I'm positive that they are. I have, however, been stymied by that same thought process when an elk walked that never should have. There's not one broadhead and arrow combination that won't kill an elk, but when the $#i+ hits the fan and things don't work out perfectly, then I want my equipment to be up to the task of making up for my mistake to the maximum extent possible. Your combination would have been a better choice than what I had last year with the 3 blade 125 grain head. I can't definitively say that this combination is better than yours, but the research results are in my favor, and that puts my mind at ease.
Post by: WDFW-SUX on May 12, 2009, 09:36:17 AM
Post by: boneaddict on May 12, 2009, 09:42:17 AM
Quote
have read it but I have not drank the kool aid yet.
:chuckle:
Post by: Todd_ID on May 12, 2009, 09:48:49 AM
I have read it but I have not drank the kool aid yet. :chuckle:
I've read it several times over the years, and I finally decided to take a sip. $48 total to try it out was worth it to me. Plus, I'll be set if I ever get to go to Africa or grizzly hunting in Alaska.
Post by: boneaddict on May 12, 2009, 09:49:53 AM
Quote
There's not one broadhead and arrow combination that won't kill an elk, but when the $#i+ hits the fan and things don't work out perfectly, then I want my equipment to be up to the task of making up for my mistake to the maximum extent possibleA-MEN, nicely put
I could probably kill an elk with my pellet gun, but doesn't mean thats what I want to use. :)
Post by: Todd_ID on May 12, 2009, 09:54:42 AM
TPI of 0.62 unable to ever penetrate
TPI of 1.27 penetrated scapula +5-8" flesh
TPI of 1.50 penetrated scapula and broke offside ribs on pass-through every time
These results are from a zebra shoulder blade, and that should be close to a really big bull's size.
My TPI last year was the .526 that was in the first post: it failed miserably.
This year my TPI will be 1.814, and I'd bet a plug nickel that it would have killed that bull!
I'm really hoping that I don't have to find out, but if I ever do hit a shoulder again, then I think I'll be happy I switched.
Post by: HawkenBob on May 12, 2009, 10:31:48 AM
This is some really interesting stuff!!
How are those single bevel heads to sharpen? I imagine they would be much easier??
Thanks!
Amen to that! This is great info. Im really glad I havent bought any broadheads yet. This sheds some great light.
as far as sharpening, this is just like my custom sushi knives. Japanese steel sharpend on one side only. I can see how it keeps rotation going and not only sharpens easier, but gets sharper too! If the steel is a proper mix, with the right heat treating the molecules are aligned perfectly for razor sharp, sharpening performance and density.
The answer to your question is yes, it does sharpen easier, but still great care and consistant angle play a major role.
Post by: Snapshot on May 12, 2009, 10:44:13 AM
I spend more time sharpening a single bevel than a double bevel but I've been sharpening doubles for thirty-five years and singles only one year; I'm sure it'll get easier. But I may not want to go much faster because I'll say this; I've never been as scared of a sharp double bevel as I am of a sharp single bevel. They can be honed to a wicked sharp edge.
Post by: Machias on May 12, 2009, 10:54:13 AM
Post by: HawkenBob on May 12, 2009, 11:04:54 AM
Post by: Todd_ID on May 12, 2009, 11:14:37 AM
Post by: Ray on May 12, 2009, 11:47:43 AM
Post by: Machias on May 12, 2009, 11:51:45 AM
Post by: Todd_ID on May 12, 2009, 12:09:17 PM
I've taken more than a few animals with 2 blade heads and can't really remember a bad blood trail on any of them. Those were with the old Fred Bear Razorheads in the 80's and more recently with the Magnus Stingers.
If he had them stand up to all of the research and do what they were supposed to, then I think that will work for me. The blood trails will be there.....at least that's my way of thinking.
Post by: Intruder on May 12, 2009, 12:33:49 PM
How does actual broadhead sturdiness play a role in this? I'm guessing that if the broadhead cannot maintain it's integrity alot of this is for not. Is there much info on the relative ruggedness of these various heads?
Post by: Machias on May 12, 2009, 12:34:58 PM
Post by: Machias on May 12, 2009, 12:38:04 PM
This is one hell of an interesting discussion. I totally dig the objective scientific minutia behind all this. Interesting side note by Machias.... would like to understand why there might not be "good" blood trails.
How does actual broadhead sturdiness play a role in this? I'm guessing that if the broadhead cannot maintain it's integrity alot of this is for not. Is there much info on the relative ruggedness of these various heads?
Some of the older broadhead blades would peel when they came in contact with bone. I don't think it's near as much a problem nowadays as it used to be.
Post by: Todd_ID on May 12, 2009, 01:07:16 PM
I've lost blades on several heads in elk and deer over the years: Satellite, Wasp, Muzzy 3 blades, Bear Razorheads, and Rocket Ultimate Steel that I can remember. I think the bleeder blade on the Bear Razorheads fell out in flight before reaching the animal because they were never on there when you found your arrow! The ones that haven't come apart on me were Snuffer SS (one piece), Slick Trick, Magnus Stinger, and Thunderheads.
Post by: Machias on May 12, 2009, 01:25:43 PM
Post by: boneaddict on May 12, 2009, 01:32:40 PM
Post by: Intruder on May 12, 2009, 02:17:42 PM
Post by: Machias on May 12, 2009, 03:21:36 PM
Post by: Todd_ID on May 12, 2009, 03:33:52 PM
I've often wondered about the blood trail, but while using the stingers have had no problem at all on several moose, elk, deer and probably a few other animals. I could see it in bear with fat plugging the hole.
The last two bears I've shot with my bow have been with the Magnus Stingers. Neither of the blood trails would be described as "buckets of blood everywhere", but, also, neither of them required any serious looking to find the trail. There was no need to mark the last blood spot to look for the next. Neither bear went more than 100 yards, either.
Post by: Todd_ID on May 12, 2009, 03:38:49 PM
Machias is right: placement will always reign supreme. Sometimes, however, stuff happens that we'd like to think our equipment could make up for. I plan on being able to make the shot count when I get the chance, but who knows what can happen between release and THWACK!
Post by: Machias on May 12, 2009, 03:42:54 PM
Post by: Todd_ID on May 12, 2009, 06:19:39 PM
Post by: Todd_ID on May 12, 2009, 06:24:42 PM
As a safety note to those trying this out with the Lansky: keep your finger under the handle to prevent your thumb from riding up the frame and into the bottom (already sharpened) blade. This should save a finger or two from the dumb mistake I made. :bash:
Post by: bow-n-head on May 12, 2009, 06:34:35 PM
Post by: Machias on May 12, 2009, 06:37:48 PM
Post by: Todd_ID on May 12, 2009, 09:04:48 PM
Post by: Todd_ID on May 12, 2009, 09:11:19 PM
Here's a picture to show the relative sizes in broadheads; my floor is 4" bamboo boards.
From Left to Right: 290 Grain Grizzly (1-3/16" cut), 125 grain Magnus Snuffer SS (1-1/16"), Rocket Ultimate Steel 100 grain (7/8"), Slick Trick 85 grain standard (1").
(https://hunting-washington.com/smf/proxy.php?request=http%3A%2F%2Fi194.photobucket.com%2Falbums%2Fz213%2Ftoddr96%2FDSC_0095.jpg&hash=e78631efd75ad68e61a83afe4e58fb9364cd1bc0)
Post by: Intruder on May 13, 2009, 07:28:58 AM
Post by: Todd_ID on May 13, 2009, 07:53:36 AM
Post by: Intruder on May 13, 2009, 08:15:28 AM
Loss of speed and pin gaps are the main reasons brought up I'd guess. I'd counter with the fact that I can set my pins to match whatever range I decide and always use my rangefinder on anything over 40 yards. Loss of speed is not a consideration for me when I look at the gains in momentum that come from using the heavy arrows. Downrange momentum is much greater with the heavy arrow also, because the mass retains the velocity much better. Slow arrows are much better for penetration too, because friction (what stops an arrow) doesn't go up linearly, it's exponential. So double the speed is quadruple the friction.Makes sense.... I was w/ ya up to the point about friction. How does that work... is that a function of the spin or sumthin? Not wrappin my mind around that.
Post by: Todd_ID on May 13, 2009, 08:16:26 AM
High FOC balance allows the better penetration because the broadhead is pulling the arrow through the animal instead of the weight of the shaft trying to push it through. With normal FOC arrows as the broadhead hits the animal the arrow starts pushing and bends upon impact. This bending/oscillating at impact creates a great deal of friction from the shaft as it is trying to work its way through the flesh; this is greatly reduced with the high FOC arrow.
Post by: Todd_ID on May 13, 2009, 08:24:46 AM
Makes sense.... I was w/ ya up to the point about friction. How does that work... is that a function of the spin or sumthin? Not wrappin my mind around that.
Friction is the force that opposes the momentum force of the arrow when it hits either a target or an animal. This opposing force (friction) is what slows, and ultimately stops an arrow. The faster something is flying, the greater the friction buildup is. Think of putting your hand out the window of the car going 20 mph; there's relatively little friction (wind resistance). Now speed up to 40 mph; the amount of wind resistance didn't double; it quadrupled, making it much harder to hold your hand out. The same thing happens when an arrow is stopped. A slow arrow encounters less friction than a fast arrow in the same target. Traditional guys have know this for years; their arrows out penetrate targets when they're shooting next to their buddies with compounds.
I've seen this with the two arrows I put on the first post. The slow, heavy arrow penetrated through the target to bury in about 2" before the FOB. The lighter, faster arrow didn't come out the back side of the target.
Post by: bucklucky on May 13, 2009, 09:13:43 AM
Post by: Intruder on May 13, 2009, 09:38:35 AM
But the same weight arrow that is faster will out penetrate wont it?? There is more than just friction working against you and for you in this equation. A faster arrow of the same weight will carry more power longer than the same arrow that is slower. Am I thinking right? The heavier arrow just holds its momentum longer than a light arrow?? Im trying to wrap my brain around that as well ;)Without knowing all the ins and outs this makes sense to me. It's kinda like talking about energy in bullets. It doesn't mean a whole lot unless you're talking about bullets that don't vary too much in weight. Momentum is a much better objective measure of penetration ability than energy.
I'm guessing that friction as a result of speed, while a factor, doesn't mean as much as some of the other measures when trying to determine penetration and or killing capacity. Seems like there are other forces at work that would contribute or diminish friction.... broadhead sharpness, broadhead shape, arrow diameter, arrow slickness, fletchings, etc. All of these would effect friction upon impact in some way regardless of speed.
Post by: Ray on May 13, 2009, 09:55:18 AM
Quote
High FOC balance allows the better penetration because the broadhead is pulling the arrow through the animal instead of the weight of the shaft trying to push it through. With normal FOC arrows as the broadhead hits the animal the arrow starts pushing and bends upon impact. This bending/oscillating at impact creates a great deal of friction from the shaft as it is trying to work its way through the flesh; this is greatly reduced with the high FOC arrow.
The science behind it has a little bit more. The example I read said something to the effect of - the arrow sort of bends or crumples when it hits the target. Having the weight up front reduces the drag by decreasing the amount of bending on the arrow as it strikes , enters and passes into or through the target.
A faster arrow is not necessarily better according to the studies. I have no PHD and I just shoot arrows. :dunno: However the study seems to make sense.
Post by: Intruder on May 13, 2009, 10:01:14 AM
I have no PHD and I just shoot arrows.
No kiddin... at some point ya can't get too wrapped up in the nitty gritty. I've always found that if you poke holes in vital organs, things die :chuckle:
Fun discussin it all though...
Post by: Todd_ID on May 13, 2009, 10:58:43 AM
Next, you're right in assuming that a heavier mass will retain more of it's energy down range. Like Ray's reloading example, only that with bullets you can put more powder in to change the force pushing the bullet. With a bow you can only get out of it what you put in (the area under the draw force curve minus efficiency losses). You'll notice that the lighter arrow had 78 ft-lbs of KE, and the heavier arrow had 81 ft-lbs. I've seen this happen many times with different weight arrows. The bow is able to put a bit more energy into a heavier arrow, thereby eeking out a little bit more efficiency from the bow.
All things being said, I'd much rather hit an elk with a broadhead designed for penetration with a high FOC and 81 ft-lbs than 78 ft-lbs and a questionable design.
Post by: bucklucky on May 13, 2009, 11:08:23 AM
Now go spend the money and upgrade your bow ang gain 20-30 fps and see how your numbers come out. :chuckle: OK probably not worth the $800.00 for a new bow ;)
Great info !
Post by: Todd_ID on May 13, 2009, 03:53:23 PM
Post by: Hornseeker on May 14, 2009, 10:12:53 AM
I've been going back and forth between 2 blade single bevels and 3 blade heads for a long time. I am an Ashby fan for Sure! I have settled...for now anyhow... on using a 3 blade snuffer or Razor cap on deer/antelope/bear with 19+ FOC and using a grizzly or Abowyer head on my elk arrows... I REALLY like the holes that the snuffers and even the smaller razorcaps makes... But Ashby's reports on penetration through bone are just too convincing for me to ignore for my elk arrows...
My buddy killed a bull with a 160 griz last year, probably in the 17% FOC area and he went about 70 yards and there was a boat load of blood on the ground.
Ive heard a lot of stories about blood trails and single blade heads... but on the other hand... I've hear a LOT of stories about great bloodtrails too....???? :dunno: I am a little nervous about it...but only time will tell!
Todd...I sure hope you get some of these arrow/heads in some critters this year... I hope I do too!!!
Ernie
Post by: EastWaViking on May 14, 2009, 10:31:01 AM
Post by: Todd_ID on May 14, 2009, 11:17:10 AM
Beman ICS Hunter 340 with 100 grain Muzzy MX3 has always worked well for me. Clean pass through every time, broadside or quartering away. I even had a clean pass through double shoulderblade shot on a WT buck several years ago. I can't really say how they would do on elk yet..... I'll let you know when I actually get a shot at one.
Let's hope that when the shot comes it doesn't hit the shoulder. All this theoretical stuff is for when you do accidentally get into the shoulder; some of us have been unfortunate enough to hit there with a setup like yours with miserable results. That's why we've gone 5 pages bantering this about for so long. You'll kill elk with that setup, no doubt in my mind, but I really don't think it'll make it through a shoulder if you happen to glance off a branch or hit your sleeve with the string.
Post by: EastWaViking on May 14, 2009, 12:01:31 PM
Post by: boneaddict on May 14, 2009, 12:02:59 PM
Post by: EastWaViking on May 14, 2009, 12:05:28 PM