The Phalanx CIWS is a close-in weapon system for defense against anti-ship missiles, aircraft, small high-speed surface craft, helicopters, surface mines etc. It was designed and manufactured by the General Dynamics Corporation, Pomona Division (now a part of Raytheon). General Dynamics Ordnance and Tactical Systems produces the 20mm M61A1 Gatling gun (Vulcan cannon) and ammunition handling system for the Phalanx Close-In Weapon System prime contractor Raytheon. Because of their distinctive barrel-shaped radome and their automated nature of operation, Phalanx CIWS units are sometimes nicknamed “R2-D2” after the famous droid character from the Star Wars films.
The Block 1B Surface Mode configuration builds on earlier capabilities with the addition of an Optimized Gun Barrel (OGB) for an improved dispersion pattern and an integrated Forward-Looking Infrared System. The new OGBs are 18 inches longer than the original M61A1 gun barrels, are substantially thicker, and include both a barrel brace and muzzle restraint to improve longevity and projectile dispersion patterns. The Enhanced Lethality Cartridge provides a 50 percent increase in penetration mass. The Phalanx FLIR provides a unique capability to search, track and engage littoral warfare threats while simultaneously providing a significant improvement in ASM engagement ranges.
The Block 1 CIWS mounts also fired at 3,000 rounds per minute with an extended magazine drum holding 1,550 rounds. The velocity of the rounds fired is about 3,600 feet per second (1,100 m/s). The rounds are armor-piercing tungsten penetrator rounds or depleted uranium with discardable sabots. The Phalanx CIWS 20 mm rounds are designed to destroy a missile’s airframe and make it unaerodynamic, thus keeping shrapnel from the exploding projectile to a minimum, effectively keeping secondary damage to a minimum. The ammunition handling system has two conveyor belt systems. The 20 mm APDS rounds consist of a 15 mm penetrator encased in a plastic sabot and a lightweight metal pusher. Shells fired by the Phalanx cost around $30 each and the gun typically fires 100 or more when engaging a target.
Phalanx Close-In Weapon System (CIWS) production started in 1978 and has been used by multiple navies around the world, notably the U.S. Navy on every class of surface combat ship with the exception of the San Antonio-class LPD, by the Canadian Royal Canadian Navy, the British Royal Navy, and by the U.S. Coast Guard aboard its Hamilton and Legend-class cutters. The Phalanx is used by 15 other allied nations. With over 850 systems now produced for 24 nations, production contracts are in place to carry further development well into the 21st century.