The key to knife "stopping power" is stab placement, primarily the eye sockets and the throat. This takes a lot of skill and practice. To test your accuracy take a cardboard box and draw a circle around a quarter on it. Now put it roughly head high. Draw and open your knife from wherever you carry it and stab the circle as fast as you can. If you can repeatedly draw and hit somewhere in that circle or at least touch the edge of the line your accuracy is adequate.
That’s pretty much my position on it, it is exactly like shot placement in every way.
Placement and penetration, just like bullets.Originally Posted by fwrun
Gaping slash wounds and "blow the hide off" birdshot makes for some horrific looking injuries but give me a single deep lung/liver/heart stab or shot anyday if I actually need to put someone down right now.
"For a moment he felt good about this. A moment or two later he felt bad about feeling good about it. Then he felt good about feeling bad about feeling good about it and, satisfied, drove on into the night."
-- Hitchhiker's Guide to the Galaxy --
Yes. This is why bullets are usually more effective stoppers than stabs. Even the lowly .22 FMJ goes in 15-17”. Try that with a shank.
If you are stabbing with a Bowie though....
Anyway agree: placement and penetration.
Remember that penetration in gel ≠ penetration in human flesh in a 1:1 situation. When you say, ".22 FMJ goes in 15-17"" that's in gel, the average human isn't actually 17" thick and the heart, lungs, liver, and kidneys are only a couple to a few inches under flesh, muscle, and most importantly (for the heart and lungs) bone. When most folks talk about penetration of a blade, they are talking into flesh. To translate, remember that 12" of gel penetration is roughly 7-10" of flesh. In other words, gel shows somewhere on the order of 20-40% more penetration than flesh penetration.
The bone part is the tricky part and a lot of thoracic cavity stabs hit bone and as a result are far less effective in penetration. The sternum and upper portion of the rib cage are fairly stout components of the skeletal system, but a even a short knife driven downwards with a human's body weight on it, can punch through and reach that vital organ you need to hit. It's easier if you can move between the ribs and reach the heart, because the intercostal area isn't home to tons of muscle, actually.
We also have to remember when we're comparing penetration of a knife wound to a gunshot wound that we're not looking at the same injury. A knife gives a wider wound tract than a bullet by virtue of it's width and length (though this also means it slows exponentially faster than a bullet). And though it may not seem like it, remember that leverage + body weight = considerable force that can be exerted with the tool. Force that can easily meet and exceed the amount of force as a handgun bullet hitting flesh (while also having a wider wound tract). I'm no biomechanics expert (I'll leave that to @Clusterfrack), but just a general perusal of the human biomech literature indicates that using just the wrist (no trunk, no body weight) humans can exert ~15-20 ft/lbs of max force on a grasped lever. That's 7-10% of your .22 FMJ before you even add a knife, leverage from swinging, or body weight into the equation. That's just my way of saying, humans, even relatively weak ones, can generate a lot of leverage, unless they are mobility limited in some way.
We also must remember that as long as the knife is still in hand, force is continuously exerted on it. That's an important point, because a bullet begins losing force, effectively the instant it leaves the barrel of the gun.
That said, if we could say, launch a Clinch Pick at 2000fps, we'd really have a mean weapon. I dunno what a CP weighs, but a .700NE launches a 1000-grain (65gram/2.2 ounce) projectile at 2000fps and generates ~8900 ft/lbs of energy. That is a substantially mean and nasty amount of force for anything. Which when we get down to it, is why bigger, higher velocity, projectiles work best for incapacitating humans, because they can handily exert as much or more force than a human alone with less physical exertion on the part of the human.
And yes - totally agree with all - if you don't hit vital areas you are accomplishing very little.
Last edited by RevolverRob; 02-14-2019 at 10:40 AM.
Yes, I agree. The peak force isn't necessarily what limits the damage. Unless the blade tip encounters something hard or very tough, it can take little continuously applied force to propagate a "defect" in a viscoelastic material. It seems like the biomechanics of teeth is a good analogy? Maybe more in your field?
Last night we were working on escapes from sudden knife attacks in a MUC, and I had maybe a 25% fail rate. I've got some nice point bruises from those practice knives, and we weren't hitting very hard. I can't say I would rather get shot than stabbed, but some of my bruises are in places that could have been lethal from a single stab.
Last edited by Clusterfrack; 02-14-2019 at 11:55 AM.
“There is no growth in the comfort zone.”--Jocko Willink
"You can never have too many knives." --Joe Ambercrombie
Good point, I should look at some of the shearing forces and penetrating forces of the canines and incisors. Trouble there is gape and jaw musculature plays a big role in the force generation. There is also a ton of sensory input through the teeth that substantially changes the force rates. Mammal teeth are remarkably sensitive, capable of detecting basically 1-2 N/M of force being applied laterally. I have a good friend and colleague working on this for her dissertation, looking at the sensory system/feedback loop to the brain via tooth ligaments. It's not quite finished, so I won't spoil the fun, but I think her results will be in one of the Big 3 journals at some point late this year or early next.
This is a good anecdotal point, but one that reinforces that targeting and placement means everything. Shot in the pinky or stabbed in the liver? No contest, right? Right. Stabbed in the liver vs. shot in the liver? Much closer contest and assuming the same targeting and amount of force applied, I'm not sure which I'd rather be, shot or stabbed.Last night we were working on escapes from sudden knife attacks in a MUC, and I had maybe a 25% fail rate. I've got some nice point bruises from those practice knives, and we weren't hitting very hard. I can't say I would rather get shot than stabbed, but some of my bruises are in places that would have been lethal from a single stab.
Size matters too. Compare getting stabbed by a knitting needle vs a 12” kitchen knife (like my Paris attacker had)... A big knife is more likely to cut high flow rate blood vessels.
“There is no growth in the comfort zone.”--Jocko Willink
"You can never have too many knives." --Joe Ambercrombie
something, something..."It's not the odds, it's the stakes"...something or other
"It's surprising how often you start wondering just how featureless a desert some people's inner landscapes must be."
-Maple Syrup Actual
What we are really talking about here are relatively small concealable pocket folders. While these can be very deadly and cause very expensive to repair wounds, they are very poor fight stoppers. If you look back in history before the advent of reliable handguns, you will see that when people carried knives as sidearms the blades were generally three or four times the size of your tactical folder. It is impractical for most of us to carry the modern equivalent, a 12" Bowie or a kukri at work. Bowies are more like a short sword and could easily run a man through or lop a hand off. A single chop to the head with a kirkri can cleave a skull to the teeth. The sort of pocket knives and small daggers that you are likely to actually carry just does not have enough mass to effectively chop or slash. About the only thing left is a deep penetrating stab to something vital. The problem is that knives by their very nature sever nerves and there is generally not a lot of pain involved. This leaves only blood loss which can take a very long time to have any real effect on a determined attacker. Sure you might get an instant stop with a stab to the eye or by severing the corroded artery, but in the chaos of a real fight, most people can't count on anything better than a few random hits to the hands and arms and maybe a couple somewhere on the torso. The reality is that if you are not a pretty good puncher you are not going to be a good stabber either.
Reply With Quote