British anti-aircraft missile system SEA CAT (Mk20)

The system consists of an anti-aircraft guided missile, a launcher, and fire control equipment.

The SEA CAT missile is a small projectile equipped with rotating wings to control its altitude and direction. The cylindrical body of the missile, which widens at the front, is made entirely of light alloys, while the wings are made of reinforced plastic. The missile has a radio command control system. The antennas of the radio command guidance receiver are mounted on the wings. There are also contact fuse sensors on the wing edges. The missile is monitored visually or by radar. To ensure visual monitoring of the flight, there are luminous tracers at the ends of the stabilizers.

anti-aircraft missile system SEA CAT (Mk20)

Industrially manufactured missiles are protected by two special shells: one for transportation and long-term storage, and the other for when the missile is on the launch pad in combat readiness mode.

The first shell consists of a metal base and a cover made of glass fiber reinforced plastic. It weighs about 30 kg, is 1.55 m long, has a diameter of 0.71 m (the length of the guided missile is 1.47 m), and a maximum wingspan of 0.66 m. The missile is stored in artillery cellars or on deck in this shell. After loading, the shell is removed. In general, the entire design allows the launcher to be loaded manually by a crew of two. It takes about a minute to install and prepare the missile for launch.

The second protective shell is a plastic film that tightly covers the missile and is attached to the base, thereby hermetically sealing it from the environment. When the missile is launched, the shell bursts along specially prepared seams.

There are three variants of the main anti-aircraft missile system:

• improved (using a television control system)
• lightweight
• combined

The basis of the first is the Mk20 GWS20 (Guided Weapon System Mk20) guided weapon system. Depending on the scope of the improvements, the weapon system was given a new designation each time. Currently, Amazon-class frigates are equipped with the GWS24 system.

The target can be tracked visually using an optical and television system, as well as “blind” using a radar station. The optical system is controlled manually, the television system is controlled manually (automatically) remotely, but under radar control, the radar is controlled only automatically remotely.

When generating guidance commands, corrections for wind, ballistic characteristics of the missile, and the location of the complex's equipment are taken into account.

anti-aircraft missile system SEA CAT (Mk24)

In the improved version, the SEA CAT air defense system is paired with a 114 mm Mk8 artillery mount in a single complex using a two-channel automated fire control system WSA4 (Weapon System Automation Mk4). To track the target, this control system uses two RTN-10X Orion radars (also known as Type 912) with conical beam scanning (X-band), whose antenna columns are equipped with television tracking system cameras and control elements. The radar is capable of rapid frequency tuning. The station's antenna can be rotated 360 degrees in azimuth and from -30 to +90 degrees in elevation.

The Type 912 radar station can supplement the main detection radars. When the station is operating in search mode, the air target detection range is over 37 km. The station is controlled and monitored manually from the operator's control panel.

The viewing angle of the TV camera changes. When the missile is brought into line with the target, the TV camera has a wide viewing angle, which is then reduced to increase the sensitivity of the TV system. To avoid tracking a false target, a strobe system is provided, which presets a small viewing angle for the sector where the missile is calculated to appear. Once the object is automatically brought into the line of sight of the target, the operator controls the flight of the missile using a handle on the control panel.

The total weight of all the equipment of the anti-aircraft missile system is about 1,600 kg. The British ST-801 radar with anti-jamming circuits can be used as a target detection and tracking radar. The use of a television control system brings the characteristics of this air defense missile system closer to the improved version of the basic complex.