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Bullet-Proof Sheets of Carbon Nanotubes
An anonymous reader notes a CNN.com report on Nanocomp Technologies, the first in the world to make sheets of carbon nanotubes. "In April, [CEO] Lashmore had a mechanical multicaliber gun shoot bullets at different versions of his sheet, each less than a fifth of an inch thick. ... Army tests show the material works as well as Kevlar. The military also hopes to replace copper wiring in planes and satellites with highly conductive nanotubes, saving millions of dollars in fuel costs."
That's an interesting question, but doesn't it apply to kevlar too? We've had kevlar vests for years, but no ammunition made of kevlar that I've heard of. Maybe the material isn't suitable to be shot out at high speeds/pressures?
TFA doesn't say that it will stop artillery. It says they fired a "mechanical multicaliber gun" at 1,400 feet per second. It doesn't say what calibers or bullet weights they were using but the speed of 1,400 fps suggests that they are testing it against handgun equivalents. There are many off the shelf rifle calibers that will easily achieve twice that velocity. It would be interesting to see if this material is proof against them or if it's only useful against handguns.
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We are the United States Government! We don't do that sort of thing.
Artillery projectiles need to be heavy, not hard. Lead is good, depleted uranium is better. Not obvious where carbon NT can improve that.
"Buy Thompson's Carbon Nanotube Bullets. The only nanotubes tough enough to penetrate nanotubes."
Oh, yeah, it's not easy to pad these out to 120 characters.
Kevlar and carbon nano-tubes are not particularly dense. The ideal projectile material is extremely dense, its why lead and depleted uranium are often used instead (or in conjunction with) of hard brass or steel.
People also used leather as armor, but so far no one has dug up a leather sword. The physical properties of kevlar as used for armor are entirely different from the physical properties of a good bullet. Kevlar has very high tensile strength allowing it to spread the impact over a large area by deforming and pulling on all the threads around it. With a bullet, you want all the force located in one small, strong, pointy area for penetration; which is why armor penetrating rounds are jacketed or tipped in a metal much stronger than lead or copper(steel, tungsten, depleted uranium).
Orwell was an optimist.
In the 1980s I worked in advanced ceramic materials development for Corning. We were pitching insulating sleeves to be cast into cylinder heads. At a meeting with the Ford SVO engineering group, one of their engineers said "The first thing you hear about a new material is always the best thing you will hear about it. After that, the 'yeah, buts' begin." Yeah, but is it safe? Yeah, but is it affordable? Yeah, but will it conduct / dissipate heat? Yeah, but is it environmentally friendly? It takes time for systems to be redesigned around the special attributes of revolutionary materials.
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All or most armor manufacturers use a table top mounted "test gun" that they can change out the barrel and receiver to fire different caliber to test the protective effectiveness of their product. I don't think anyone can buy one of these you have to get them specially built.
If you ever watch any History or Discovery channel show(s) about fire-arms chances are they show a few of these.
Not that I'm defending wasteful military spending, but the reason they want this is not so much for the dollar savings on fuel, but for the logistical advantages of needing less fuel: extended range of existing aircraft, reduced need for aerial refueling, more sorties on the same fuel budget, etc.
Yeah, but won't the existing technology develop to do the same job faster and cheaper than this one can be got to market? That's why wood, ceramics, iron and cement are still the base materials of civilisation, rather than titanium, magnesium and carbon fiber.
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Oh yeah, not to reply to myself, but shortly after high school I did some patent drawings for a cylindrical weapons mount you could load into a 120mm smoothbore cannon and inside the mount you could configure a .308, .50 cal or 25mm match grade barrels attached to an trigger mechanism that could be activated remotely while loaded in the main cannon of an Abrams.
This was supposed to be used for training purposes using ammo already found in the US Armory stores.
IIRC they went with a German training aid instead.
you want all the force located in one small, strong, pointy area for penetration; which is why armor penetrating rounds are jacketed or tipped in a metal much stronger than lead or copper(steel, tungsten, depleted uranium).
Actually, the advantage of DU isn't its strength but its density:
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...That's some tough sheet!
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If they could make it work it sounds like it would be a great material for a bullet resistant vest.
Although getting hit with a taser while wearing one ...
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Lightweight and hard (not necessarily strong) are not necessarily what you want in a bullet. Hard bullets destroy the rifling in the weapon. There are smoothbore guns, but not too many. Lightweight bullets don't retain their energy well over time.
The trend in artillery is for really heavy rounds, like Depleted Uranium or thin Tugsten spikes launched inside of a Sabot. If anything came from this in a prjectile I assume it would come from the Silver Bullet style like the high speed tugsten spike.
but the tip of a whip is the fastest thing short of a fighter jet.
Or a bullet. Or a photon. Or the speed with which you will roll your eyes at my corrections ;)
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A few years back, the trend in armor-piercing rounds was the teflon-coated brass round. They are now banned, though not for the Teflon coating (which wears off in the barrel or peels away in flight), but because of the hard cores.
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My guess is it's more about the weight. carbon nanotubes are about 1/7th the density.
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The fuel cost savings comes in the form of weight. Copper is likely a lot heavier than the carbon nanotube material. Less weight, less fuel to keep the plane aloft. Alternatively, they could use it for carrying heavier payloads.
"Saving millions on fuel costs"
There is very little energy wasted in copper wiring, especially in airplanes! Moving to a material of higher conductivity will result in minuscule savings, and will be nowhere remotely close to covering the cost of the (extremely expensive) materials.
They aren't going to save fuel because it is more conductive. They aren't burning tons of fuel because of transmission losses from one end of the plane to the other.
They are going to save fuel because the nanotube wires will be lighter than the copper wires we use now. Less weight == less fuel.
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It's not about resistive losses. It's about weight. Also carbon nanotubes haven't benefited from any economy of scale efficiencies, and hence the cost is likely to be much less once they are able to be manufactured in quantity. It's not like carbon is a rare material.
I missed that lesson in history class. The one where the Roman Legions are beset by the whip-wielding Visigoth horde. On a side note, I'm pretty sure whips are only effective against Dracula and Nazis.
A 747 has approximately 190,000 feet of copper wiring - per this. I would imagine that that translates to quite a bit of weight - if that weight were to be reduced significantly (by half or better) - the fuel savings would not be negligible. The other place suggested for their usage was in satellites - which is a market where the cost is per kilogram - and satellites, as they are now, I'm sure owe quite a bit of their weight to the wiring that makes them function.
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For clarification, Teflon coating of projectiles is designed to reduce barrel wear, and has nothing to do with penetration.
Most ammo manufacturers now use molybdenum coatings - not sure if that is because it is more effective, or because of the dumb "Teflon-coated cop-killing bullets that go through a bullet-proof vest!" bullshit the Brady group shrieked about in the 90s. FWIW, most any rifle bullet will penetrate light armor, and there are several surplus rounds that can even penetrate level IIIa from a pistol - 7.62x25 Tokarev being the most popular, in the CZ-52.
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You know, considering some of the bears you might be facing would be several hundred pounds, and several times stronger than you, maybe you wouldn't want a "bear suit" to be light weight. Just cause their claws and teeth couldn't puncture the suit, doesn't mean they couldn't throw you into trees, pin you to the ground, or knock you into the water. Sometimes weight is a good thing. Unless of course, you are trying to outrun the bear, which you can't do...
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Well its really both it's density and hardness. The Brinell hardness of U-238 is 2,400, which is just shy of tungsten at 2,570. Iron is 490.
Also, DU has incendiary properties (somewhat similar to magnesium) which make it great as an artillery shell.
It doesn't list the calibers used in TFA, so hard to be a judge. I shoot 1/4" steel plates all day with a .223 without much damage to them - though a lot depends on the bullet type. Lead bullets will splash, lead-nose jacketed bullets will shatter, steel-core will damage or penetrate. Step up to a .308 and good ammo, you're going to need 1/2" or more to have a chance of stopping it.
A .50? The only time I've shot steel with a .50 BMG, it penetrated the 3/4" steel plates I had like they were paper.
If I had to guess, they're talking about handgun rounds, though - in which case, it sounds pretty equivalent to Kevlar. Kevlar isn't just a "sheet", though, as a single sheet is easy to penetrate - its more about the way they interlock when layered, causing the bullet to apply its force to a greater surface area before penetrating.
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Bear to another, so this guy comes over in his lightweight 'bear proof' suit, I tried clawing him - no effect, I tried biting him, no effect, I tried shouting at him, no effect. So I sat on the bugger until he stopped wriggling.
This is so typical. Someone discovers how to make a sheet of carbon nanotubes, and the first thing they do is shoot at it. Where is the study telling us how huggable these nanotube sheets might be?
In that case we should try to make armor out of Jello. That way we trick them into trying to attack us with Jello instead of bullets. Not to mention the mass of new recruits we'll get when people hear they get paid to be in a giant Jello fight.
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There is already a material out there that is better than Kevlar, it's called Spectra. It's an ultra-high molecular weight polyethylene and despite its existence Kevlar continues to be the standard.
Something needs to be *a lot* better to displace an established standard, not just somewhat better.
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Pretty sure it's not under STP.
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Emphasis mine.
Fuck. 1400 fps is fast.
But can it play Crysis?
You're thinking of a shaped charge round.
This
But I dare say that military perspective is not on saving fuel costs. After all, why save money by putting in a smaller fuel tank when you can keep it the same size and use the fuel savings to fly further/faster?
It equals out to the same thing.
If you need to drop a bomb on someone 100 miles away, right now it costs you $100 in fuel to do it. If you replace all your copper with nanotubes and make the plane lighter you can do it for $90 in fuel.
If you need to drop a bomb on someone 110 miles away, right now it'll cost you $110 and you'll have to refuel somewhere along the line. Make the plane lighter with nanotubes and now you can do it for $100 in fuel and no refueling along the way.
Even if they don't make the fuel tanks smaller, they'll still be saving money.
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Interesting anecdote: When I was in the service (Army Infantry), some of the older sargents got to talking about unusual ammunition that they'd used/tested/heard about. Depleted Uranium came up, because it was before the first Desert Storm and no one had used it before. The other one still hasn't been used that I know of. It was a hollow plastic nose & metal cup round filled with liquid teflon.
The story went that during Viet Nam, a sniper was sent to wound some particular General, not kill him. He wasn't the greatest strategist, so we knew how to handle him, and didn't want him dead, but for some upcoming engagement we wanted him on the sidelines, so he was marked for a wounding and not a dirt-nap. They sent the sniper out with these new liquid teflon rounds to try. Mistake. When the round hit the General in the shoulder, the liquid came out in strings and tore his whole arm and shoulder off, inducing massive shock and bleeding him out in seconds.
Probably BS, but makes for an interestingly morbid story.
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Carbon nanotubes act a lot like asbestos in our lungs. We don't know that it is carcinogenic yet, but in the initial reaction that CNT causes in mouse lung tissue is the same sort of reaction that asbestos fibers cause. It's not surprising because CNT are so similar to asbestos fibers. They are nanoscale fibers, they are highly resistant to chemical degredate. So I think it would be safer to assume that it is a probably human carcinogen and behave like it is so that 20-40 years from now we don't have hundreds of thousands of people with CNT related lung cancer.
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The problem isn't the cost of the fuel, it's the cost and lost opportunities from the long supply train. Most non-lopsided battles aren't determined by who has the better equipment or even the better soldiers but by who has the better quartermaster.
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The ideal projectile material is extremely dense...
Carbon nanotubes are known to be toxic. Wouldn't having them next to your body in a situation where you are likely to bleed be kind of unnerving? http://www.newscientist.com/article/dn13946-nanotubes-toxic-effects-similar-to-asbestos.html
The definition of AP ammo is at 18 USC sec. 921(a)(17): "(B) The term `armor piercing ammunition' means- (i) a projectile or projectile core which may be used in a handgun and which is constructed entirely (excluding the presence of traces of other substances) from one or a combination of tungsten alloys, steel, iron, brass, bronze, beryllium copper, or depleted uranium; or
(ii) a full jacketed projectile larger than .22 caliber designed and intended for use in a handgun and whose jacket has a weight of more than 25 percent of the total weight of the projectile.
It's important to note that this subsection relates ONLY to ammunition which can be loaded in handguns. There are few shops with CNC lathes which turn out solid brass bullets, supposedly of highly uniform density metal, which are sold to be hand loaded for long range shooters. Steel and tungsten core rifle ammo is commonly available--or at least it was before all the hoarding hullabaloo.
This is the reason why FN Herstal couldn't ship the 5.7x27mm cartridge with the SS190 Steel/Aluminum core bullet. It can be used both in their PS90 carbine and FiveSeven pistol. If they only marketed the carbine in the US, an argument could be made that they would be legally able to ship the SS190 ammo, as it isn't intended for handguns, and by definition isn't armor piercing ammo, per federal law.
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Despite the fact that the .357 magnum fires both .357 and .38 "caliber" rounds, the reality is, it is not really multi-caliber. .38 caliber is actually .357 caliber. The difference between the rounds is not the width of the bullet, it's the powder charge. The reason .38 is called .38 despite only being .357 inches wide, is because it is a throwback to older days when they measured the width of the shell casing instead of the width of the bullet.
As for shell length, the .38 shells are mostly empty. The reason they are the length they are is because they were first made before smokeless powder was invented. Smokeless powder is far more compact, and so when they switched to the new powder, they didn't have to use anywhere near as much in order to get the same energy release. They kept the shell size to make sure older guns were still compatible with it. As for why you can't use a .357 shell in a .38 gun, it's because of pressure constraints; a .38 can't handle the energy of a .357 round, and would probably explode if you attempted to fire one. For that reason, and that reason alone, the .357 is about 1/8 of an inch longer; i.e. so that the round won't fit into a .38 gun accidentally.
it's probably the strength, using copper in air-frames pulling 10 G's is challenging, carbon-NT could hold up under 100's of G's such as guided artillery rounds or missiles that would turn a human pilot into jelly.
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