Phalanx CIWS
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The Phalanx CIWS (Close-in weapon system, pronounced see-wiz) is an anti-missile system that was designed and manufactured by the General Dynamics Corporation, Pomona Division. It is now manufactured by the Raytheon Company. It is used by the United States Navy on every class of surface combat ship in its fleet and is used by navies of over twenty allied nations. Because of their distinctive barrel-shaped radome and their automated nature of operation, Phalanx CIWS units are sometimes nicknamed R2-D2s, after the famous droid from Star Wars.
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[edit] Overview
Developed as the final line of defense (terminal defense or point defense) against anti-ship missiles (AShMs), including high-G and maneuvering sea-skimmers, the first system was offered to the U.S. Navy for evaluation on USS King in 1973. It was accepted and production started in 1978, the first ship fully fitted out was USS Coral Sea in 1980. The Navy began placing CIWS systems on noncombatant vessels in 1984.
The basis of the system is a 20 mm M61 Vulcan Gatling-type rotary cannon linked to a radar system for acquiring and tracking targets. The gun fires at a variable 4,500 rounds per minute (hydraulic models only fired 3,000 rounds per minute): it is mounted in a self-contained turret along with an automated fire control system. The system automatically searches, detects, tracks, engages and confirms kills using its computer-controlled radar system. Because it is self-contained, Phalanx is ideal for support ships which lack integrated targeting systems and generally have limited sensors. The entire unit weighs 5625 kg or 6120 kg.
Phalanx has been developed through a number of different configurations. The basic style is the Block 0. The Block 1 (1988) offers various improvements in radar, ammunition, rate of fire, increasing engagement elevation to +70 degrees, and computing. These improvements were intended to increase the system's capability against emerging Soviet supersonic anti-ship missiles. Block 1A introduced a new computer system to counter more maneuverable targets. The Block 1B PSuM (Phalanx Surface Mode, 1999) adds a forward looking infrared (FLIR) sensor to allow the weapon to be used against surface targets. This addition was developed to provide ship defense against small vessel threats and other "floaters" in littoral waters and to improve the weapon's performance against slower low-flying aircraft. The FLIR's capability is also of use against low-observability missiles and can be linked with the Rolling Airframe Missile system to increase RAM engagement range and accuracy. The Block 1B also allows for human intervention to identify and target threats.
The U.S. and Canada are in the process of upgrading all their Phalanx systems to the Block 1B configuration. The Block 1B is also used by other navies such as Japan, Egypt, Bahrain and the Royal Navy[1]
[edit] How the CIWS Works
The CIWS is designed to be the last line of defense against anti-ship missiles. Due to its design criteria its effective range is very short relative to the range of modern SAMs, from 1 to 5 nautical miles. The gun mount moves at a very high speed and with great precision. The system takes minimal inputs from the ship making it capable of functioning despite potential damage to the ship. The only inputs required for operation are 440 V AC at 60 Hz and chilled water for electronics cooling. For full operation including some non-essential functions, it also has inputs for True compass ships heading and 115VAC for the PASS and tape drive subsystems.
[edit] Radar Subsystems
The CIWS has two radars that work together to engage targets. The first radar is the search radar, located inside the dome on the weapon control group (top of the white painted portion). The search radar does exactly that - searches for any targets and takes note of which direction they are traveling, how fast, their exact position and other information. When the search radar identifies a potential target (see details below), the mount moves to face the target and then hands over the target to the track radar. The track radar is an "orange peel"-style radar that is more precise, but can only view a much smaller area. The track radar observes the target until it decides when the optimum opportunity to fire is, and then depending on the operator conditions, it will fire automatically or will recommend fire to the operator.
[edit] Gun and Ammunition Handling System
The Block 0 CIWS mounts (hydraulic driven) fired at a rate of 3,000 rounds per minute and they could only hold 989 rounds in the magazine drum. The Block 1 CIWS mounts (hydraulic) also fired at 3,000 rounds per minute with an extended magazine drum holding 1550 rounds. The Block 1A and newer (pneumatic driven) CIWS mounts fire at a rate of 4,500 rounds per minute and also had the larger 1550 round magazine. The velocity of the rounds once fired is approximately 3600 feet per second (1100 m/s). The rounds are armor piercing penetrator rounds with discarding sabots. The rounds utilized are comprised of the heavy metal depleted uranium. The kinetic projectiles are designed to pierce and explode an incoming missile's warhead. Use of otherwise more effective high explosive shells would risk destroying the missile airframe while allowing the warhead to continue a ballistic trajectory into the ship. The ammo handling system uses 2 conveyor belt systems. One of the systems takes the rounds out of the magazine drum and takes them to the gun. The second conveyor system takes either the empty shells or non-fired round and routes them back to the drum at the opposite end they came out from.
[edit] CIWS Contact Target Identification
The CIWS does not recognize Identification friend or foe, also known as IFF. The CIWS has only the data it collects in real time from the radars to decide if the target is a threat and to engage it. A contact has to meet multiple criteria for it to be considered a target; some of the criteria are listed below.
1) Is the range of the target increasing or decreasing in relation to the ship? The CIWS search radar will see contacts that are out-bound and not pay attention to them. The CIWS will only engage a target if it's approaching the ship.
2) Is the target capable of making a maneuver to hit the ship? If a target is not heading directly at the ship, the CIWS looks at its heading in relation to the ship and its velocity. It then decides if the target can perform a maneuver to still hit the ship.
3) Is the target going between the minimum and maximum speeds? The CIWS has the ability to engage targets that travel in a wide range of speeds; however it's not an infinitely wide range. The system has a target maximum velocity limit; if a target exceeds this velocity, the CIWS will not engage it. It also has a minimum target velocity, meaning any target going below that velocity will not be engaged by the CIWS. The operator also has the option to adjust the minimum and maximum limits within the limits of the system. The actual limits are classified.
What is described above are the basics of how the CIWS works. There are many other subsystems that run in the background to ensure proper operation, such as environmental control, transmitter, mount movement control, power control and distribution and so on. It takes 6 to 8 months to train a technician to be qualified to perform maintenance on, operate and repair the CIWS. The 6 to 8 months for training are a specialized school that follow a 9 month training course.
[edit] Phalanx in combat (at sea)
The Phalanx system has not been openly credited with shooting down any enemy missiles or aircraft.
February 25, 1991, during the first Gulf War, the USS Missouri and the Phalanx-equipped USS Jarrett were in the vicinity of an Iraqi Silkworm missile (often referred to as the 'Seersucker') that had been fired, either at Missouri or at the nearby HMS Gloucester. After Missouri fired its SRBOC chaff, the Phalanx system on Jarrett, operating in the automatic target-acquisition mode, fixed upon Missouri's chaff and fired a burst of rounds (not destroying the incoming missile). From this burst, four rounds hit Missouri which was two to three miles from Jarrett at the time. There were no injuries.[2] The Silkworm missile was then intercepted and destroyed by a Sea Dart missile launched from Gloucester. Incidentally, this is the first validated, successful engagement of a missile by a missile, during combat at sea.
June 4, 1996, a Japanese Phalanx accidentally shot down a US A-6 Intruder. The US plane was towing a radar target during gunnery exercises. A Phalanx aboard the Asagiri class destroyer Yūgiri locked onto the Intruder instead of the target. Both pilots ejected safely.[3] A post accident investigation concluded that the Yūgiri's gunnery officer gave the order to fire before the A-6 was out of the CIWS engagement envelope.[4]
Phalanx is considered inadequate against some modern threats and is being gradually supplemented and replaced by the Rolling Airframe Missile, which has greater range and higher hit probability. The RAM system uses an automated and self-sufficient radar fire control similar to that of Phalanx.
[edit] Land based version
The U.S. Army's version of the Navy's CIWS Phalanx anti-missile system is called the "Land-Based Phalanx Weapon System" (LPWS). It is a type of "C-RAM" (counter-rockets, artillery and mortars) defensive weapon.
Whereas naval Phalanx systems fire depleted uranium or (more recently) tungsten armor-piercing rounds, the LPWS uses the HEIT-SD (High-Explosive Incendiary Tracer, Self-Destruct) ammunition originally developed for the M163 Vulcan air-defense system. These rounds explode on impact with the target, or upon tracer burnout. With a reliability of between 95 and 99 percent the odds of live rounds falling on "friendlies" is minimal.
[edit] Similar systems
- AK-630, Russian CIWS
- Goalkeeper CIWS, Dutch CIWS
- Meroka CIWS, Spanish navy
- SeaRAM, U.S. missile-based CIWS
- Type 730 CIWS, Chinese CIWS
[edit] Notes
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