Friday, October 30, 2015

Ways To Strike With A Knife

The ways in which you might cause damage to an opponent when using a knife might seem obvious, but there is more to this ubiquitous weapon than just cutting people.  As mentioned in my previous post, most knives can be used as both an edged weapon and a pointed weapon.  That covers the slashing and stabbing that people associate with knives.  But let's not neglect the potential of the other parts of the knife.

As an example, let's look at my CRKT M16-04Z.

Closed position

"Stay away from me if you know what's good for you" position
Just for reference, the blade is 4 inches long (in Texas, you can legally go up to 5.5 inches).  From end to end, it's about 9.25 inches.  Here's what it looks like in my hand.

If we're not friends and you see me like this,
your day is not likely to improve

As I said, the blade and point are the obvious danger zones of this weapon.  But there are some other ways of striking with it.  For example, look at the part of the handle that protrudes out from the bottom of my hand.  It may not be "sharp" per se, but it's enough of a corner to do some serious damage as an impact weapon.  I'm a big fan of hammer fist strikes already.  So this part of the knife just augments those strikes.  In the Apache Ghost Dog system, striking with that part of the handle is called an "eagle's beak".  If you've ever had, the back of you hand hit in knife sparring with one of know it hurts badly.

Let's not forget that the blade (particularly the one on this knife) is a slab of metal with some weight behind it.  Beyond the cutting/stabbing parts of the blade, hitting someone with the flat of the blade can be jarring and painful.  In sparring, I do this using a whipping motion similar to a back fist strike.  I use it to either hit my opponent's weapon out of their hand or to just do damage to their hand.  It's very fast and gives up a minimum in terms of openings.  In the Apache Ghost Dog system, this is called a "snapping turtle".  When you feel it, you'll know why.  Now obviously, if you have a little blade, this isn't going to be as effective as, say, a bowie knife.  So, know your weapon.

Now, most knives that people carry around these days are folding knives rather than fixed blades.  Just because a knife isn't in the open position, doesn't mean that it can't do damage.

Closed position, in hand
As you can see, I still have the eagle's beak strike available to me.  I also have a similar strike on the other end.  If effect, a closed knife is like a kubaton, which is a small impact weapon like the one below.
Spiked kubaton

You should also note that my knife fits excellently into my hand, weighting it for more devastating punches.

It's not a roll of quarters, but it'll do

So, even in the closed position, I have heavy punches and impact weapon potential for hammer fist strikes on either side of my fist...all before I even deploy the knife.  This can be useful knowledge when faced with a self-defense situation in which you are able to pull your knife but don't quite have time to open it.  Hit the bad guy somewhere painful, and when you have a couple seconds to open your knife, do so.


Knives are dangerous weapons in many ways, obvious and non-obvious.  I didn't mention throwing your knife, but that's a possibility as well.  Though I'm more in the camp of "why would I throw away a good blade?"  All of this is just to highlight the point of my last article that weapons can fit into multiple categories.  So, understand what you can do within a weapon category and you can quickly figure out how to effectively use any weapon that fits into those categories.  In this case, knowledge of pointed, edged, impact, and even projectile weapons will help you to more effectively use knives.

Thursday, October 22, 2015

Weapon Taxonomy

There are a lot of different weapons out there. If you include all of the "traditional" martial arts weapons then the variety seems to grow tremendously.  If you want to be as effective as possible in a self-defense situation, then you'd better have some weapons skills, but does that mean that you have to practice with as many different weapons as possible in the event that something strange or exotic is available in a fight?  Thankfully, the answer is a definite "no".

What you should practice with are some weapons that are representative of their entire category.  If you don't know what the categories of weapons are, then read on.

Like the classification of living things in biology, weapons can be grouped (and subgrouped) based on their characteristics.  A good taxonomy will have non-overlapping categories.  So, I'll do my best to meet that standard here.  Keep in mind that while the categories don't overlap, there are weapons that fit into multiple categories.  Not to worry though.  If you understand how to fight with each of the categories, then that multi-category weapon will work just fine for you.

1. Projectile
2. Impact
3. Edged
4. Pointed
5. Flexible

Let's look at some examples.

I love my XDM
Guns are the typical example of projectile weapons, but they aren't by any means the only projectile weapons.  Assuming that stinger missiles and ICBMs aren't in your arsenal, any of the following would also constitute projectile weapons.
Throwing knives...of movie fame

The ever popular "ninja" star
Yes...this is a rock

Anything that you send through the air counts as a projectile.  Let's look at some impact weapons, which are basically anything that you use to hurt someone by running into their body really fast while it's still in your hands.

Here's the typical rattan stick ala Filipino martial arts a stick with an extra handle

Nunchucks are good for bashing people...
that definitely counts as an impact weapon
I witnessed the two year old version of my little brother
smash the skull of my older brother with one of these.
It looked like it hurt.  So, this goes here.
The ubiquitous folding chair of pro wrestling fame

And just to make this explicit, you could use a gun as an impact weapon by simply bashing someone with it.  Try not to knock it out of battery or jack up your optics, know...don't die either.  Keep your priorities straight.

On to edged weapons...which are anything with a sharp enough edge to slice flesh open.

CRKT M16 Z ... never leaves my side
"Butcher" knife

Straight razor
A shard of broken glass will cut you as easily as
any knife will

I used a typical knife as the first example because that's what people tend to think of when the term "edged" weapon is used.  However, technically it is both an edged AND a pointed weapon (but nobody really bothers to say that...because it's inconvenient).  Edged weapons need not be pointed and pointed weapons need not be edged.  As we will see below.  Oh yeah, and all these examples except for the glass have impact potential...and they all have projectile potential.  Anyway!  Pointed weapons...

Prison shiv #1

Prison shiv #2
The school yard favorite...

Ergonomic handle for really driving that sucker deep

So yeah, anything that you can stab somebody with counts as a pointed weapon.  If you're really talented, then maybe you could turn these into projectile weapons.

Of all weapon categories, flexible weapons is probably the most neglected.  Or at least, only a very small subset of these weapons have any sort of popularity.  We've already seen the nunchucks, which are a sort of flexible/impact weapon crossover.  But that's just scratching the surface.

Three piece staff ala China

Kusari fundo ala Japan
Flail ala...miscellaneous European countries...I don't know

I actually wear this kind of belt virtually every day.  The
metal doesn't look like much, but I could break someone's
bone with it I'm sure.

Here's the famous Dan Inosanto using a sarong (ala Indonesia)
to make some poor guy's day a little less pleasant
Flexible weapons have a "bendy" part.  They can be used to grab, immobilize, and strangle.  When weighted, they can be used as effective impact weapons as well.

That is about it for categories of weapons.  If you can understand how to use each of the categories, then you should be able to use just about anything that you pick up to defend yourself adequately.  You should be able to improvise just about any object into a weapon of some kind.  Adaptability is key.

I've been thinking a lot about various weapons and their applications in self-defense scenarios.  So, expect to see more along this vein in upcoming posts.

Thursday, October 15, 2015

Rock, Paper, Scissors...Stab!

Recently, I saw a video that inspired me to make a new drill for my students.  The video took place in a kendo school.  Two opponents knelt in front of each other.  Between them were two toy hammers and a big bowl.  They then proceeded to play rock, paper, scissors.  The winner grabbed the hammer and tried to hit the other guy's head.  The loser grabbed the bowl and tried to use it as a helmet as quickly as possible.  If a clean shot was landed, then a point was awarded.

Beyond the comedic value of the video, I instantly saw a framework for what will likely be many games/drills at my dojo.  The first of which I will do this Saturday and will proceed as follows.

Two opponents will kneel in front of each other about one and a half arm lengths apart.  In front of them will be two training knives, one for each of them.  They will play rock, paper, scissors.  The winner gets to grab their knife and will have 3 seconds to cut the other person.  The loser must defend through blocking, parrying, and/or disarming.  If the loser gets cut (probably restrict this to vital areas), then he or she has to do 5 push ups.  If they tie, then they can both grab a knife and the same rules apply.  If you lose the rock, paper, scissors battle and you grab a knife anyway, then you do 10 push ups on top of whatever else happens.

I'm pretty sure that's going to be a lot of fun.  I like the drill for several reasons.  First, there's a randomness to it.  Often in martial arts drills, roles are assigned and everyone knows what they're supposed to do and when they're supposed to do it.  It lacks a certain realistic uncertainty.  Even having an instructor call out which person is supposed to attack can lead to some psychological predictions on the student's part because the instructor will inevitably want both sides to get an even number of tries at either role.  The rock, paper, scissors pre-game eliminates all of that.  The students have to be ready to attack or defend at a moment's notice.  Second, because of the uncertainty, there's a requirement to be not only physically quick but mentally quick.  I'd argue that mental quickness is the more important of the two in a fight.

I'm actually quite looking forward to trying out this new drill/game.  I have a feeling that there will be some push ups to be had...

Wednesday, October 7, 2015

Stopping Power? Physics and Bullets

Being a martial artist, the topic of guns comes up frequently.  When it does, the issue of what caliber of ammo is best usually gets brought up along with the all-too-popular point about "stopping power".  Stopping power is often brought up by proponents of larger caliber bullets (.45 and up).  The argument tends to go along the lines of claiming that the bigger bullet has a better ability to stop a bad guy that's coming at you.  Rather than conjecture about whether or not it's a valid point, let's use some science to figure this out.

First off, let's agree that Hollywood movies do not constitute sufficient evidence of stopping power.  Ridding our minds of the images from movies that bias our thoughts on the effects that bullets have on the human body can be difficult.  That's why we have to let the science and math speak on the issue.

The most relevant physical law at play here is the law of conservation of momentum.  The momentum of an object is calculated simply by taking the product of its mass (m) and its velocity (v), mv.  The law of conservation of momentum basically states that the combined momentum of two interacting objects will be the same before and after the interaction.  To put it in a formula:

m1v1 + m2v2 = m1v1' + m2v2'

Here the apostrophe after the velocities indicates the post-interaction velocity of the given objects. 

 An example of this type of interaction might be a bowling ball hitting a bowling pin.  Initially, the pin has zero velocity and the ball is moving at some speed.  After they hit, the pin is now moving (in the direction perpendicular to the tangent of the ball at the contact point) and the ball has slowed down somewhat.  If this didn't happen, then the ball would just smash through the pin, the back wall and whatever was behind the Juggernaut.

I'm the Juggernaut!  Once I start moving I can't be stopped!
This is bad for science but awesome for action scenes!
In much the same way, we can look at a bullet hitting a human being and what effect that might have on his momentum.  In other words, we can use the above formula to calculate just how much a bullet will slow someone down.  Cool, huh?

Now, the was to affect momentum as much as possible is to have a "sticky" interaction, which means that the two objects stick together when they hit each other.  A bullet that passes right through a guy isn't going to affect his momentum by much.  So, let's assume that the bullet fully embeds in the bad guy (of course the target is a bad guy...we only shoot bad guys...right?!).  I'm also going to make a bunch of other assumptions that will only help the "stopping power" argument.  Like I said earlier, people who argue for stopping power tend to carry .45 caliber and up.  Let's look at some stats on the .45 ACP round:

mass: 230 gr (15g)
velocity: 270 m/s

That's not too shabby.  But for the sake of this exercise, let's assume that our hero's pistol fires .50 BMG bullets.  (That's the big one in the picture below.)

The stats on this bullet a bit more impressive:

mass: 800 gr (52g)
velocity: 882 m/s

Enter the bad guy.  The average weight of a human male in the USA (according to wikipedia) is 195 lbs, but we're going to say our bad guy weighs only 150 lbs (68 kg).  Let's say that the bad guy is charging at our hero.  Now, this morning I ran 1.4 miles at about 3.5 m/s, which is NOT fast and certainly wouldn't qualify as an attacking speed.  So, let's assume that our bad guy is not only small but also slow, traveling at a mere 3 m/s.

To summarize:

The bad guy:
m= 68 kg
v= 3 m/s

The bullet:
m= 52 g = 0.052 kg
v= -882 m/s  (negative because the bullet is going in the opposite direction as the bad guy)

Post-impact (sticking together):
mm= 68.052 kg
v = ?

We want to use the above formula to solve for v.  (Who's up for some algebra?)

To substitute in the values that we know...

68 kg (3 m/s) + 0.052 kg (-882 m/s) = 68.052 kg (v)
158.136 kg m/s = 68.052 kg (v)
which means...
v = 2.33 m/s

v is positive, which means that the bad guy-bullet combo is still moving in the same direction as the bad guy was going before the impact.  In fact, a FREAKING .50 BMG bullet that COMPLETELY LODGED into the LOW WEIGHT bad guy was only able to slow him down 2/3 of a meter per second.

I won't bore you with more math, but the results for a more realistic situation involving a .45 ACP bullet and an average weight US male traveling at a typical sprinting speed (9 m/s) would be that the bullet would only slow down the bad guy by LESS THAN 0.05 meters per second.  That's not much given most altercations happen at a distance of less than 6 feet.  


Even if your bullet hits a major off switch, a knife wielding bad guy might still fall on you and cut you if you don't move out of the way.  It doesn't matter if you're firing .22 caliber bullets or a .50 BMG.  Personally, I carry a 9mm because it has MORE BULLETS.  With more bullets, I can shoot more bad guys or lay down some cover fire to allow me or someone else to move.   Many people will swear by their preferred caliber, and they may very well have their reasons.  Just don't let "stopping power" be one of them.

Springfield XDM 9mm Compact
19 bullets using the full-size mag...19!!