Phalanx CIWS: Encyclopedia II - Phalanx CIWS - How the CIWS Works

Phalanx CIWS - 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 (exact range is classified). The gun mount moves at a very high rate of 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 input that is required for operation is for it to receive 440VAC at 60Hz. 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.

Phalanx CIWS - 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.

Phalanx CIWS - Gun and Ammunition Handling System

As stated above 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 and newer (pneumatic driven) CIWS mounts fire at a rate of 4,500 rounds and the magazine drum holds approximately 1550 rounds. The velocity of the rounds once fired is approximately 3600 feet per second. The rounds are armor piercing penetrator rounds with discarding sabots. Originally they were made using depleted uranium, later upgraded to tungsten. The ammo handling system uses 2 conveyer belt systems. One of the systems takes the rounds out of the magazine drum and takes them to the gun. The second conveyer 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.

Phalanx CIWS - 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, which 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 are 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, operate and repair the CIWS.

Adapted from the Wikipedia article "How the CIWS Works", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki