Slashdot Mirror
Israeli Company Creates Nano-Armor
Izeickl writes "According to IsraCast, an Israeli company has created materials made of inorganic fullerene-like nanostructures (IFs) which have amazing shock absorbing properties. During preliminary tests, these materials, which are five times stronger than steel, have successfully resisted to steel projectiles generating pressures as high as 250 tons per square centimeter. These materials could be incorporated in "nanoarmors" able to protect soldiers or police forces within three years."
Due to the nature of their job who is going to get shot at more, the Army or police? Obviously it's the Army. So why shouldn't they get this armor?
"Armed forces abroad are of little value unless there is prudent counsel at home" - Cicero
Depeleted Uranium is used because it is:
A) Of comparable density to tungsten
B) Easier to work with than tungsten
C) Far cheaper than iridium or ozmium, which are denser.
D) Self-sharpens instead of mushrooming (like tungsten does) when it passes through steel.
Recently hippie groups have begun to call DU and WP "chemical" weapons on the grounds that DU is a toxic heavy metal and white phosphorus is a poison if injested.
This is, of course, ignoring the fact that the World Health Organization doesnt think DU is dangerous at all (unless your the one being shot at) and WP in a military application dosent kill by poisoning but rather by *burning people alive*.
So yeah, DU is used for density, economy, workability and self-sharpening and is categorically not a chemical weapon.
more muzzle velocity, yes. better armor piercing ability, not likely.
As a physics major, let me explain my understanding of firearms:
I believe the bullets would (all else being equal) receive the same kinetic energy (1/2*m*v^2), so if the bullet was half the mass, it would go sqrt(2) times as fast. At least at the end of the muzzle. After that (and to a lesser extent, before) air resistance affects the bullet proportional to v^2. Since v^2 is twice as large for the smaller bullett, the force would be twice as large, and due to the lower mass, the lighter bullet would decelerate much quicker (starting at 4x). This is a rather complex differential equation (because of the square), but what's likely to happen is that at any large distance, the lighter bullett will probably hit the target moving slower.
Now, when the bullet impacts the target I believe it's the pressure that actually does the damage. Pressure is force per unit area, and the areas would be the same (although here the analysis could possibly fail, if the lighter bullet held a pointier shape for longer). At point-blank range (or ignoring air resistance) and treating the force the target exerts as spring-like (probably good approximation for armor), the force needed to stop the bullets would be the same on each bullet (because the energy is the same so they would deform the target the same amount). Factoring air resistance back in, the lighter bullet will reach the target with less energy, and so exert less pressure. If the lighter bullet doesn't deform, it's possible that the pressure would be greater, dealing more damage.
Conclusions:
1. A lighter bullet will hit the target at a slower velocity.
2. Assuming the same deformation upon impact, the lighter bullet will deal less damage.
3. If the heavy bullet deforms and the light doesn't, the light one *might* do more damage.
This is my best guess, but it's possible I made a mistake somewhere.
Your point about velocity is taken, though, since delivering the same number of Joules in less time can make a difference in how well the impactee material holds up.
.44 magnum and the lead bullet flies through the torso and out the other side, you're not getting the most efficient impact possible, because the slug hasn't transferred all of its energy into the target (it still has enough KE left to fly out the exit wound). If the bullet were aluminum, for instance, it would have less mass and more velocity, AND it would probably stop in the target, thereby causing more trauma.
An often-overlooked point about ballistics. How quickly and efficiently the projectile's energy is transferred into the target is a huge determining factor in how damaging it is. If you shoot someone with a
A few quotes to back you up.
i ts-components.html
"There is a myth of "cop killer bullets" that can penetrate body armour and then expand to kill the officer wearing it. This is pure fantasy. A bullet can be designed to penetrate armour or it can be designed to expand in soft tissue. It CANNOT do both. The "teflon" coating on the much maligned Black Talon ammunition is simply an aid to reducing barrel fouling in the handgun. It does nothing to enhance the bullet's ability to penetrate body armour. Many hunting bullets are coated with different compounds these days." http://www.nfa.ca/for-journalists/ammunition-and-
"Armour piercing bullets are a specific design which incorporates a hard steel or tungsten carbide penetrator inside the bullet's core. Only ammunition with this hard penetrator design is considered to be armour piercing. When the bullet impacts armour, it begins to flatten. As the nose flattens, the hard penetrator continues forward into the armoured surface while being supported by the bullet as it continues to flatten.
Armour Piercing bullets do not explode, fragment or do any of the things you might see in a Hollywood movie. They are a simple kinetic energy penetrator. AP bullets are mainly found in military ammunition." http://www.nfa.ca/content/view/162/76/
And yes, I feel like being a Karma Whore today.
Life is not for the lazy.
Do a bit of math here. Newton's third law says for every action there is an equal and opposite reaction. So, if a projectile were to deliver enough energy to break a persons neck after hitting an impregnable helmet, the soldier that made that shot would suffer from a broken shoulder.
I was thinking about this the other day. Conservation of momentum only means that the force applied to the target by the bullet as it deccelerates will be equal to the force applied to the bullet, which is why it deforms. The force applied to the gun firer will be different. I think.
The kinetic energy the bullet has will do work on the target, which if the bullet is fully stopped, will be equal. That work, as newton meters, will result in a large force over a short distance (very short if it doesn't penetrate the armour). That force then follows the 3rd law, and is applied to the target and the bullet, which bruises or breaks bones and squashes the bullet.
The gun performed work on the bullet to give it that kinetic energy, but because of the barrel length, means that a smaller force must have been applied over a longer distance; that smaller force is then applied to the firer's hand and/or shoulder, due to the third law. (the 3rd law also dicates recoil; a bullet accelerates fast in the barrel, due to a small mass, while the heavy gun accelerates slower backwards due to a larger mass. If the soldier is tightly gripping the gun, then they both will accelerate backwards even slower; if he's got a solid stance, then the earth will rotate backwards with him a very very tiny bit)
So the energy applied to the bullet at firing will equal the energy applied to the target (or less a bit, if you include air friction); but the two people will experience different forces. That's why you can fire a high power rifle that will blow a hole right through body armour, but won't break your shoulder.
Of course, I've gone about this the wrong way; gun manufacturers work on creating a force on the bullet (amount of gunpowder) that will give a high muzzle veocity, without applying dangerous force to the firer. Air resistance will dictate the effective range of the weapon, and the muzzle velocity and range will determine the energy applied, and thus the eventual force applied to the target.
Anyway, back to the point. Stronger body armour doesn't mean less energy applied to the target, it just means that the force from the bullet is spread out over the surface of the armour, rather than going through it and applying force to the squishy bits in your body cavity directly as it slows down. Our bodies survive larger diffuse impacts at the surface better than small holes in organs, so stronger body armour means better survivability, even if the impact does hurt like hell.
Incidentally, I'm right there with you on necks. The ease with which a villain's neck snaps is right up there with the likelyhood of cars exploding because they rolled over when it comes to suspension of disbelief. Oh, and that getting stabbed once or twice in a random area kills you instantly. Human beings survive trauma a lot longer than films usually give them credit for - unless they're the hero, in which case they always shrug off wounds that would disable a normal person from shock.
Remember kids, it's all fun and games until someone commits wholesale galactic genocide.
"How about teflon-coated bullets?"
FWIW:
The teflon coating found on many armor-piercing rounds for small arms has no effect on the armor-piercing ability of the ammunition. The teflon coat is to protect the barrel from excess wear caused by the hard materials of the projectile. Armor-piercing properties come from the composition of the projectile or from a insert of a harder substance incorporated into the projectile.
Friends help you move... Real friends help you move bodies...
Nice to know your vest will stop a handgun but if a
Most modern armies use body armor and helmets even if they don't help against rifle bullets. Why? To protect against shrapnel (which iirc accounts for about 80 % of casualties in full scale warfare). So even if this doesn't protect against rifle bullets, it isn't exactly useless as long as it's an improvement over the standard kevlar stuff.
You are correct for the most part, but you are ignoring one important factor. The amount of powder used is scaled for the size, or mass, of the bullet so it reaches the desired muzzle velocity (which should be on the upper end of what drag makes practical). The heavier bullet will have more energy (and momentum) and therefore be more effective for armor penetration. Its a similiar to the reason uranium (twice the density of lead) is used in anti-tank rounds. Your target velocity can always be achieved by tossing enough explosive behind your round (or bullet) so the real driving factor is density, the heavier it is, the more effective it will be.
The primary determinant for how much energy the bullet receives is how long the bullet stays in the barrel, giving the powder time to burn; this is why, for instance, a carbine has a much higher muzzle velocity than a pistol firing the same round. (On the other side of the coin, you could make a pistol chambered for rifle rounds, but it wouldn't be terribly useful; most of the powder would escape from the muzzle and burn up in the air, creating a hell of a muzzle flash but no extra velocity.) So a lighter bullet will have a higher muzzle velocity, but it probably won't be enough higher (increasing as the square root of 1/mass) to give it equivalent energy to a heavier bullet. Barrel length and powder burn speed are the most important factors. Typical rifle rounds are in the 22 to 30 caliber range, while typical handgun rounds are in the 38 to 45 caliber range, and while the rifle bullets are longer, they still run a bit lighter on average than the handgun bullets -- but they have much, much higher muzzle velocity and energy.
.45 pistol round, about the biggest practical pistol caliber for most people, which will usually be about half again its weight. Guess which one hits the target harder?
...) One problem with small, fast bullets is that they can go right through the target, leaving a hole almost exactly the size of the bullet*, and not actually doing that much damage. Bullets which deform inside the target dump all their energy right there, and therefore have much more "stopping power." This is one reason, perhaps the primary reason, why the M16, despite having evolved into a pretty reliable weapon over the years since its disastrous first iteration in Vietnam, remains controversial. Many infantrymen, whose lives depend on "one shot, one kill," and medics, who see the results up close and personal (I've been both) believe that our troops would be better served by the older, heavier style of military rifle round. Not necessarily the 7.62 x 51 mm (NATO), which is overkill for anything but a sniper rifle or a machine gun, but say the 7.62 x 39 mm (Warsaw Pact) used in the AK. There's some benefit in being able to carry more ammunition with the smaller rounds ... but more benefit in being sure that the guy on the other end of your sights is going to go down when you hit him.
.45 ACP) are about the best single-round choice for self-defense there is, because not only will they take down the target, if you miss they're much less likely to go through three walls and kill your neighbor's toddler. Even better is a short-barreled 16-ga. shotgun.
You're right about lighter bullets losing velocity faster, of course, but it's not as much a determinant as you might think -- consider the difference between a 7mm rifle round, which is a mid-sized hunting round, and a
Now, all that being said, deformation on hitting the target is a good thing. (Er, good from the shooter's POV, not the target's
* Forget all that crap you hear about "cavitation" and "small hole going in, big hole coming out." It's a myth, based on studies of firing bullets into blocks of gelatin which do not behave, in the least, like human (or animal) bodies. If you're looking for a weapon for self-defense, you will always be better off with a bigger bullet, as long as you can handle the weapon. Period. And big slow bullets (e.g.,
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
That would depend on how dense this stuff is.
In the Society for Creative Anachronism, people can fight in various amounts of steel armor and wield rattan swords. This always includes a helm and some other mandatory armor.
One man got the idea to make his mandatory helmet out of titanium. Titanium is stronger than steel, but less dense. When he went into combat that day with his new helmet, he took one good whack to the head that someone wearing a steel helm would have shrugged off. With his lighter titanium model, he was knocked unconscious and got a concussion. The helmet was undamaged, however.
It all goes back to physics: action, reaction, momentum.
Hail Eris, full of mischief...
E pluribus sanguinem
Actually, if you want to kill an unarmoured target, your best bet is to have both high energy and high velocity. Any bullet will have a primary, mechanical effect, much like a stab wound. Unless a vital organ is punctured, death will only occur through bleeding or infection. If you can get enough energy to dissipate within the target (which gets easier to achieve the more the bullet deforms), as a secondary effect, hydraulic pressure will cause damage to organs situated further away from the bullet channel (because, as the parent mentioned, innards don't behave like gelatin, which is a good thing when you want to eat what you kill...)
Finally, high velocity rounds (above 800 m/s) can cause neural overload.
This is why modern hunting ammuntion is designed with high, delayed expansion in mind, as well as with high energy with a focus on velocity rather than on sheer bullet mass (unless skin is hard to break, which calls for old style heavy, jacketed bullets, think elephant.)
However, in a war, the wounded are much more of a hassle for the enemy than the dead (unless your enemy is the USA, because of media pressure and ridculous doctrine), which means light, high velocity, jacketed bullets will serve you better in the long run, as long as they're damaging enough to still incapacitate without killing outright.
When it comes to controlling the effect, bullet structure is as important as its mechanical parameters on entry. As for self-defence for civilians, going non-lethal is your best bet to stay free through the aftermath: 12-gauge coarse salt cartridges aren't dead yet.
Generally the one who first occupies the battlefield awaiting the enemy is at ease; the one who comes later and rushes into battle is fatigued. Therefore those skilled in warfare move the enemy, and are not moved by the enemy. - Sun Tzu
We occupied Iraq, jihadists are coming to us there. We seem to be in agreement with the Tao in this case.
Vietnam was lost because the US fought an enemy on their own ground, where they could defend and hide as a native force.
Perhaps you have a poor translation of Sun Tzu but it is the virtuous force, not the native force that has the advantage. Or perhaps you know little of Sun Tzu's teachings beyond out of context quotes. We virtually wiped out the Viet Cong. The Viet Cong were not a virtuous force, as their failure to spark revolution in the Thet offensive demonstrated. When you have a native force that relies on brutality and fear, as in the Viet Cong case, an external force will find natives willing to provide them with intelligence and guides so that the external force will understand the terrain, tactical, and stragic situations. Sun Tzu provides ample lessons regarding defeating a native force on their home ground.
Your understanding of US history is a bit superficial, pop culture like again. The Vietnam war was not lost in Vietnam. It was lost in the US. North Vietnamese general Giap failed in his seige of Khe San, Giap failed in his Thet offensive in that it failed to spark the popular uprising, the Pentagon failed in that through its conduct it lost credibility and the Thet Offensive was erroneously received as a defeat by the US public. Giap's victories occured in the US, not in Vietnam. The US was able to eventually force North Vietnam to accept terms where they recognized the existence of South Vietnam's government and the US left. Later North Vietnam violated this treaty and invaded the South, ironically this was a very conventional invation, heavy armor and all, and would have been defeated had the US provided assistance to South Vietnam. However the political climate in the US prevented such assistance.