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Polyethylene Bulletproof Vests Better Than Kevlar
teflonscout writes "When I think of bulletproof vests, the first word that comes to mind is Kevlar. Wired is running a story on Dynema SB61, a bulletproof material that is made of polyethylene. It is a higher grade of the plastic found in Tupperware. The story also mentions the recall of Second Chance bulletproof vests that were made from Zylon, a material that degraded slowly when exposed to moisture. At least one police officer was injured when a bullet penetrated his Zylon vest. Polyethylene is impervious to moisture. The first vests made from this new material are 5mm thick and can stop a 9mm bullet traveling at 1777 feet per second, which is slightly better than other top of the line vests."
Can't wait to see The Box O' Truth give it a try.
Dragonskin was kicked out of the running due to failures with angled shots and not standing up to temperature variance.
Or you could just get some Dragon Skin armor that will take the force of an exploding hand grenade and not allow penetration...
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http://www.pinnaclearmor.com/body-armor/dragon-sk
Mr. McGuire: I want to say one word to you. Just one word.
Benjamin: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin: Yes, I am.
Mr. McGuire: Plastics
the density of Kevlar is 1.44, while polyethylene is 66% as dense at around 0.94 to 0.96, will actually float in water.
Most current suits of body armor can stop a pistol caliber bullet. Rounds designed to pierce armor, or designed to be fired from a more powerful gun, are another story. Armor that will stop a small, soft bullet will still be penetrated by a faster, or less malleable one.
For civilian or police protection, we have nearly impenetrable suits now; increasing their coverage, or decreasing their weight would be more practical (both of which can be achieved by making them out of lighter materials). For something like military protection, well, we may never have impenetrable body armor. Whenever defensive technology gets good enough, the military turns their attention to piercing those defenses; see for example the death of the battleship as a viable class of warship.
Apart from that, conservation of momentum applies. There is an upper limit whereby body armor would remain intact, while the flesh beneath is reduced to a pulp. Though admittedly conservation of momentum also applies to the shooter, and to the recoil of their gun, so there is a similar upper limit for muzzle velocity per unit of projectile mass.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
1) You are equating weight with stopping power for different materials. That is an incorrect comparison. That might make sense when comparing two vests of the same material and design. Vest A has 10 lbs of Kevlar, Vest B has 20 lbs Kevlar. Both vests are of similar designs and Vest B should be better at stopping bullets. However if another company designed a different type vest (Vest C) with Kevlar that had better stopping power but only used 10 lbs Kevlar, the use of weight alone in comparing effectiveness would not be valid.
2) Body armor is heavy, especially considering all the other gear a soldier has to carry. If body armor was lighter and provided the same amount of protection, many soldiers would prefer it.
Well, there's spam egg sausage and spam, that's not got much spam in it.
Best part is that most "saves" the vests are credited with are from car accidents, where the vest acted as extra support, etc. for the spine and whatnot....
Don't blame me, I voted for Kodos
Soft body armor is designed to defeat handgun bullets, which is why it is so useful for police. Hard body armor is much bulkier but is designed to defeat rifle rounds. In general, a rifle round is significantly more powerful than handgun rounds.
This is one of those cases where allegory is truly misleading. The article makes the comparison to shopping bags and tupperware in order to emphasize the "everyday" nature of the material. The truth is that they have similar basic components, but the exact composition and processing differences cause one material to be good at resisting bullets and another at storing food (or selling at parties.) Unlike Tupperware, Dyneema vests are composed of woven and laminated fabric.
Dyneema is actually a trade name for a thread derived from Ultra High Molecular Weight polyethylene. The intrinsic strength of the material comes from the ability to increase the length of the polyethylene chain to extreme lengths. Since the structure of UHMW derives its strength mostly from the intermolecular Van-der Waals forces, the longer the polythethylene chains get, the stronger the forces holding the material together become. When the processing of the polythylene allows the length of the chains to become uniform, then you can engineer it into useful forms, such as a fiber which eventually be formed into fabric, then laminated and put on your chest.
Of course, being UHMW, Dyneema has a weakness: Its melting point is about 300 degrees Fahrenheit, or about the temperature of a hot light bulb. Which means that while your body heat might not harm the vest, carelessness in storage might.
Independent tests do not support the army's conclusions. Since there is already some question about the validity of the army's tests (e.g. the designer of the vest that "won" in the army's test says that dragon skin is actually better, the person who conducted the army tests left to work for a dragon skin competitor, etc.) I don't think just repeating the army's conclusions (or quoting the Washington Compost as doing so) really proves anything.
--MarkusQ
As with anything, the devil's in the details. From a previous trip around the web in re: bodyarmor.
It's not Tupperware, but 'Ultra high molecular weight polyethylene'.
See also:
Spectra
Dyneema
Aramids (from "aromatic polyamide")
- Example: Twaron
Kevlar, of course.
Also Nomex - known for it's heat-resistant attributes, also strong. It's an "aromatic nylon, the meta variant of the para-aramid Kevlar."
I remember this, too. Unfortunantely I also have forgotten many of the details. IIRC, this was proposed as a riot-proof window, made of a special plastic that could endure an insane amount of punishment. I believe the video was from a test done by a SWAT team because the company manufacturing the products wanted to sell their windows to some division of the government.
The guys attempting to trash the window only got a large slit into the window, and while the company had deemed the windows "indestructable", they still got a passing grade because the slit in the window was not large enough to get in (or out of). They threw everything at the window, from rocks, bottles, to all sorts of heavy weaponry, and still only a slit (and the window was no longer clear.)
Something that stood out to me was how the window absorbed bullets. Rather than bouncing off (and possibly hurting others) the bullets would actually stick into the plastic, and remain there.
Does anyone else remember this?
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If you mean assault rifles rather than assault weapons, you're right. Assault rifles, by definition, fire rounds of intermediate power; between handgun rounds and traditional rifle rounds. An assault weapon could fire anything from .22 short to .50BMG.
Either way, assault rifle rounds like 5.56 NATO and 7.62x39mm (along with any rifle round commonly viewed as suitable for deer hunting) don't have too much trouble with the body armor typically worn by police.
"Prefiero morir de pie que vivir siempre arrodillado!"
The low melting point is also not good in combat situations.
Its highly recommended to wear *cotton* and not nylon clothes, for example, because cotton won't melt to your skin if you survive an IED attack.
-- My Sig is a P228.
Strictly speaking, rifles are small arms. Generally, "small arms" is a term that encompasses anything a soldier can fire unsupported.
Reality has a conservative bias: it conserves mass, energy, momentum...
In the early 70's, guns were not as big of a deal in the US and were not treated with quite the same hysteria they now are. Mr Davis was a former marine and a pizza shop owner who had been shot several times while working. He was one of the pioneers of the bulletproof vest market. There are plenty of videos of him online, shooting himself while wearing a vest, usually with a .38. He did it at conferences around the country. I have little doubt he knew the legal implications, but was willing to suffer them to promote his business and new product. It's called a publicity stunt.
And what kind of police force would let someone walk out of the building after a stunt like that?)Have you ever seen large police stations. Usually they have a bulletproof glass booth up front with an often unarmed clerk on duty. From the story I heard (from one of his ex-employees) he was arrested on the steps outside.
It sounds like marketing fiction to me.It could be, but I did not hear it from a marketing person, just from a former manufacturing supervisor. From the other things that are easily verifiable facts, I don't find a lot of reason to doubt the account.
I'm from the small town in Michigan in which second chance was founded, and I know the entire history of the "incident"
The officer in that shooting was shot 6 or 7 times. *ONE* bullet penetrated the Zylon, and it was on the periphery of the vest. The edges of *ANY* vest are vulnerable and not as strong as center-mass.
Second chance has 960+ confirmed saves with their body armor.
What they've done to the second chance business as a result is, on the whole, a travesty. They were/are one of the few american manufacturers, and they did nothing wrong at all.
I've been using polyethylene armor on my fighting robots for years. It's extremely tough, lightweight, and relatively cheap. There was a fashion for using polycarbonate (Lexan) on fighting robots for a while, and while it looks cool (it's clear), it just can't take impact like UHMW polyethylene.
Your design to a real part online: Big Blue Saw
It's the temperature of the vest that matters, not the temperature of the air. Go outside on a sunny 100F day and touch a black car. You'll notice it's way the hell hotter than the air.
Some words about polymers for people who aren't familiar with them: First of all, plastics are polymers. There are natural polymers like cellulose, but most of them are produced artificially. Every kind of polymer has a monomer, which is basically the low-level element that mades up polymers. The physical properties of a plastic mainly depend on the monomer, but on a smaller extent on a lot of things like structure as well. Now there are special materials called composites which are macroscopic mixtures of two or more distinct materials. Fiber (carbon or glass or something else) stuff like the wings of airplanes or kevlar are composites. I believe that TFA is about a PE-and-somehting-else composite, but I haven't RTFA. Composites have a lot of nice features and some not-so-nice-one as well, like nearly impossible recycling and vulnerability to tensions orthagonal to the fibers. But if used wisely they can be really efficient.
Since I work for a large company that sells body armor, I have to know about this sort of thing to help our customers. In essence, no body armor is "bulletproof". That is why if you look at any reputable manufacturer or distributor's catalog, they will list it as "ballistic armor". While it is designed, tested, and certified to defeat a large selection of threats, there can be no guarantee that it will always stop everything. As others have noted, the type of body armor that uses these materials is designed to be concealable beneath an officer's uniform. As a result, the highest threat that it can be expected to protect against are from handguns. Rifle rounds will go right through them. Also, as a side note, ballistic armor will NOT protect against a knife, you would have to specifically purchase stab armor, which is designed differently. Combination ballistic & stab armor is very expensive, although it exists. As far as Zylon is concerned, there is no vest currently being manufactured or sold with Zylon as a component. Recently I found a couple of old vests that had been stashed away and forgotten about. Since we could not sell them (one was at about 4.5 years old, and the other was Zylon), I talked my way into getting them for free. A few days later some friends (including a police officer) and myself went out to a farm and had a fun day shooting skeet. We also shot the vests. The first was your typical Kevlar construction, and it stopped everything from .22 caliber to a .45 magnum. It would not have passed certification because of the back-face on the higher calibers (look up the NIJ's testing standards), but it still worked. The Zylon vest didn't even stop a 9mm. Interesting, no?
Patience is a virtue, but haste is my life.
While there is an ongoing debate about the quality of the current system, US troops do have bullet resistant body armor.o r
http://en.wikipedia.org/wiki/Interceptor_Body_Arm
That it will.
It won't replace a personal flotation device, however. Most PFD's provide somewhere between 11 and 22 lbs of buoyancy, depending on their type (type I having the most, though type III being the most common wearable). It'll be nice that it won't be another piece of clothing to weight you down in the water, but don't expect much help from it, either, unless other types of flotation are incorporated into its design.
You need to watch more movies. ("crotchpot cooking" is part of a line from "Good Morning, Vietnam")
I would like to know where you are getting that misinformation. No one that I know who has gone to (or is currently in) Afghanistan/Iraq has had to acquire their own body armor.
I have heard grumblings about the excessive amounts of weight with the current body armor limiting mobility, but no one I know has said anything to me about wanting anything more.
I've read late Industrial Revolution writers who have claimed that until the advent of percussion-cap-based muskets, a talented person with a crossbow or a longbow was still far more effective as a soldier than a person with a matchlock/flintlock, as regards accuracy, deadliness, and rate-of-fire. The problem was just that nobody had the time to spend getting good enough with the older weapons, while you could hand a rifle to a raw recruit and with a week's training you'd have a soldier.
The Longbow required lots of practice to achieve accuracy, and a lot of strength to operate as well.
The Crossbow required little practice to achieve accuracy - but required both time and strength to reload (though a crank-type could trade additional time to reload for a reduction in required strength). This reduced the rate of fire. So crossbows were used by lower-skilled soldiers, especially from fortified positions where they could reload behind a wall or some other barrier. Its stock (the basis of the accuracy) served as the model for those of longguns.
Early longguns had the low-training-for-accuracy, long-reload, characteristics of crossbows. But they didn't require great strength to reload. Their ammunition was also lighter to carry (though consumable rather than recoverable). A 98-pound weakling, or a soldier bone-tired after a long march, could be relied on to fire more than one shot. This was the improvement that caused them to displace crossbows even though they were not yet up to the same absolute accuracy or firing rate.
http://www.somethingawful.com/d/news/nardo-design- empire.php
Subject E-11 Blaster Rifle Calibration Still Off
From Stormtrooper Commander 09731
Date A Long Time Ago 3:51 PM
To Nardo Pace
As you know, the E-11 has come a long way since its initial prototype. Thanks to your hard work over the past three years the rifle no longer fires completely sideways, and with your latest revision, the number of casualties resulting from blaster fire being directed completely backwards has been drastically reduced.
That said, the E-11 still has some accuracy issues. We recently bolted one of the rifles to a testing mechanism so that it couldn't move even a millimeter, then set up a human-sized target six feet in front of the blaster's barrel. Shooting in two second intervals, we let the E-11 fire at the target continuously for three days.
The result? Not one shot hit the target. I realize you're busy, but perhaps we can go over the design one more time and iron this out.
It is no longer uncommon to be uncommon.
Rifles are considered "Small arms".
Pistols are considered "Side arms".
Artillery pieces are usually called "Guns". This includes Naval rifles, up to 16 inches in diameter.
Mortars and Heavy Machine guns are called "Crew served weapons".
Hope that helps.....
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"Prefiero morir de pie que vivir siempre arrodillado!"
The Yamato had 18 inch "guns".
I did wonder if someone would comment on that :)
Contrary to popular belief it is possible to be both a trekkie and a star wars fan. It's not like we're members of violent factions locked in an endless war against one another. And when we are fighting, we're more comparable to the Sharks and the Jets in West Side Story. We go out in gang colors (uniforms) whistling Jerry Goldsmith stuff while the other side whistles John Williams. I don't think any actual killing can go on, unless I were to date someone from the Star Wars clan.
Warning: Opinions known to be heavily biased.