Michael Yon’s Dragon Skin armor.
Kathryn Jean Lopez posted this extract of an e-mail from mil-blogger Michael Yon:
Yon has a point about the “manufactured controversy”–the existing Interceptor Body Armor provides excellent protection at a reasonable price, and it is now universally available to all U.S. military personnel in a combat area (not merely to combat troops, as was the case at the beginning of the war in Iraq). And there has been no “conspiracy” to keep allegedly better armor (such as Dragon Skin) out of the hands of U.S. soldiers and Marines. But for all its virtues, Interceptor is not perfect. No military system of any sort ever is, since all require tradeoffs and compromises among competing and in some cases antithetical requirements. Body armor is no different, so the real issue is whether there is room for improvement, what the costs of those improvements would be, and whether the benefits outweigh the costs. For example, we could devise body armor that provides absolute protection for the entire body against the entire range of (reasonable) threats, but it would be so massive and heavy as to prevent the soldier from moving freely. We could design armor that provides total freedom of movement, but it would not protect the soldier against the full range of threats. To understand the body armor issue, you have to know a bit about the threat, the technology, and the tactical requirements of the infantry soldier. I spent about four years reviewing body armor technology and the body armor market as part of a litigation against a major defense contractor. Basically, all current body armor (with the notable exception of Dragon Skin) works the same way: there is an outer tactical vest (OTV) consisting of Kevlar or a similar material such as Dyneema or SpectraShield, which stops low-velocity bullets and fragments through the bending and breaking of multiple plies of the fabric in the OTV. These are good against pistol rounds and grenade and artillery fragments, but they have trouble stopping more powerful rounds fired from assault rifles, high-power rifles, and machine guns. Thus, the vests have pockets into which are inserted ceramic “small arms protective inserts” (SAPIs). A SAPI is nothing more than an over-engineered dinner plate made from a high-tech ceramic (silicon carbide or boron carbide) backed by several layers of compressed Spectra or Dyneema fabric (which is polyethelene, and looks like plastic). When a bullet passes through the OTV and hits the plate, the force of impact shatters the plate and absorbs the energy of the bullet; the bullet and any residue of the plate is stopped in the backing material. Because the breaking of the plate destroys its structural integrity, the ability of the SAPI to stop a second hit is considerably less than for the first hit, the third hit is less than for the second hit, etc. The current standard in the U.S. military, applied to the Enhanced SAPI (E-SAPI) is two rounds required, three rounds desired. This is not a tactical requirement, it is one based on what industry could deliver. Optimally, an insert should be able to absorb seven or eight rounds without losing its integrity–but that is not possible with existing plate technology. It should also be mentioned that the plates are really quite fragile, and prone to breaking in the course of ordinary handling. Microscopic cracks detectable only with X-ray or acoustic inspection degrade the performance of the plates and render them questionable at best. The U.S. has to replace about 2/3 of its plate inventory every year because of breakage, and the Israel Defense Force found 30 percent of its SAPIs to be damaged even when sitting in storage and never issued to the field.
Moreover, the ability of the plate to stop a round is contingent on the velocity and composition of the bullet. The original SAPIs were designed to stop ordinary “ball” rounds, but in Iraq and Afghanistan we ran up against enemies using armor-piercing bullets, and to defeat those the Army introduced the ESAPI, which is basically a thicker, heavier SAPI. With plate technology, the only reliable way to increase ballistic protection is to make the plate thicker, hence heavier. When the enemy introduced tungsten core bullets, the latest generation of SAPIs added a thin metal plate between the ceramic and the backing, thereby further increasing weight. For a soldier, weight is always the enemy. So is bulkiness, and the existing OTV/SAPI system is bulky and heavy–fully kitted out, the soldier waddles like a turtle. The stuff is also hot, and in a place like Iraq, doing even the simplest jobs wearing Interceptor Body Armor becomes a major chore. So in looking at body armor, soldiers want three things–increased multi-hit performance, lighter weight, and greater flexibility. That was the major appeal of Dragon Skin: being composed of overlapping ceramic disks sewn into a Kevlar vest, it allowed freedom of movement, and, in theory, excellent multi-hit capability. Unfortunately, Dragon Skin does not seem to work very well against high-end threats–the disks are simply not thick enough, and there seems to be a tendency for bullets to pass between the disks. But that does not mean that the existing plate-based technology is optimal–far from it. The Army is aware of the problem and is now polling industry to set new requirements for weight, flexibility and multi-hit capability. In the long term, the Army is pursuing the idea of “liquid armor“–a magnetio-ferrous substance that is normally liquid (and thus flows freely within the body armor vest) but which becomes rigid when subjected to the force of a bullet impact. The concept has been demonstrated in the lab, but is still about a decade from full-scale testing and evaluation. There are alternative technologies available now, which promise to deliver better performance, flexibility, and reduced weight. Many of these are based on the use of ceramic cylinders embedded in polymer resin over a SpectraShield backer. In contrast to plates, each cylinder is mechanically discrete, so a hit that destroys one in the process of stopping the bullet doesn’t affect its neighbors. I have personally tested such an insert, putting ten high-power, armor-piercing rounds into it without any loss of integrity or debonding. Because the cylinders are crush-resistant, they are extremely rugged, and can be dropped, or even pounded with a hammer or an axe (something else I have done) without any breakage. Finally, because the resin in which the cylinders are embedded can be flexible, the entire plate can bend with the movements of the user, making the entire ensemble more comfortable. Unfortunately, the military seems wedded to the existing SAPI technology, and breaking into the market is extremely difficult, since one goes up against both the existing suppliers and the military R&D establishment. But I do believe this technology will eventually make it into the field, because we have reached a plateau in ballistic protection. The existing ESAPIs protect against .30-caliber armor piercing ammunition, but there is no point in trying to make body armor to protect against larger rounds, because the amount of energy carried by larger rounds increases exponentially, so that any plate would be too heavy for field use. Beyond that, the energy transferred by the round to the plate (and thence to the soldier) is so great that it will kill or injure him through blunt force trauma (i.e., even if the round doesn’t penetrate, the impact will crush the internal organs). As the number of technologies capable of meeting the ballistic requirements increases, the focus of R&D will shift to secondary issues including comfort, flexibility, and multi-hit, so that the next generation of body armor will be much more user friendly than Interceptor, making our troops much more likely to use it correctly, and further reducing U.S. casualties due to small arms, grenade, and artillery fragments.
