Tuesday, December 07, 2004

US Defenses Against RPGs

Airbags?? Here's an article on US defenses against Rocket Propelled Grenades (RPGs).

Rocket propelled grenades (RPGs) have long been the typical weapons of choice when someone wants to attack trucks and armored vehicles in Iraq. RPGs are cheap, simple to operate, and if used properly can inflict significant damage on Stryker and Bradley armored vehicles. Unarmed and armored Hummers are especially vulnerable, since the various armor kits for the Hummer are designed to protect occupants from small arms and machine gun fire, not anti-tank grenades.

One quick fix to protect the Hummer is a unique airbag system developed by a small California company that deploys a "curtain" down outside the side of the vehicle being attacked. Four bags are needed to protect all quadrants and are held in place with simple Velcro straps. A small radar detects the incoming RPG or RPGs and inflates the airbag with a carbon dioxide gas cartridge. The RPG is literally "caught" by the airbag like a pillow and slowed enough so the nose-mounted fuse doesn't detonate the warhead. Instead, the RPG ends up collapsing upon itself, shredding the secondary self-destruct fuse and looking like a stomped-on beer can. Currently, the airbag and cartridge have to be replaced after one use, but the designers are working on a reusable airbag that can simply be rolled up and put back into place.

Cost for the system is expected to run between $5,000 to $7,000 dollars and weighs around 50 pounds. The Army is in the process of awarding a contract with the goal of getting systems to Iraq within 6 months, at a initial product rate of 25 systems per month. Other systems are being refined for use on canvass-topped vehicles and the Stryker. The system has the potential to replace both the current Stryker "RPG" fence standoff metal framework as well as reactive armor systems and has the twin advantages of being lighter and less expensive than reactive armor. It's also safer around infantry than reactive armor. Multiple tests of the airbag system have been run using RPGs, with one test managing slow down an RPG enough to stop it relatively intact – forcing a stop to the tests until range safety could come out and blow it up in place.

Over the longer term, the Army is looking towards electronically "charged" armor protection. The protection scheme would be composed of an outside armored plate, a spaced gap, and an inner charged plate. Shaped charges are essentially hot streams of metal traveling at (very) rapid speed to penetrate armor. A shaped charge from an RPG or other antitank weapon would detonate, penetrate the outer armor plate, and the hot metal stream would make contact with the charged inner plate, forming an electrical circuit that ends up splattering the metal across the inner plate rather than breaking through into the hull of the vehicle.

Charged armor is a better solution than reactive armor, as it is both lighter than reactive and also non-threatening to nearby infantry. At least two manufacturers have successfully demonstrated charged armor solutions, one retrofitting a Bradley AFV with a large capacitor to charge the inner hull plate. One manufacturer has demonstrated that the Bradley charged armor can take multiple RPG hits onto the same section of the hull without penetration and was willing to show a short demonstration film to those of the proper security clearance. In theory, charged armor should work equally well against weapons with larger shaped charge warheads, but the manufacturer would not comment on any tests done in that area. Ideally, charged armor would be an integrated solution as a part of a hybrid-electric vehicle. Power would be available from the vehicle to charge the armor for protection and installing the equipment would not require an expensive rebuild from the ground up. – Doug Mohney


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