Seacat (missile)

History

Seacat was designed by Short Brothers of Belfast for use against fast jet aircraft that were proving to be too difficult for the WWII-era Bofors guns to successfully intercept. The missile was based on the Shorts Green Light prototype, itself a development of the SX-A5, a research missile based on the Australian Malkara anti-tank missile to test radio manual guidance of a short-range surface-to-air missile. It replaced the Orange Nell development programme for a lighter weapon than the enormous Sea Slug missile. The first public reference to the name Seacat was April 1958, when Shorts was awarded a contract to develop a close-in short-range surface-to-air missile. Royal Navy acceptance of Seacat as a point defence system instead of the Bofors L60 and the more effective Bofors L70 with proximity fused shells was controversial as many doubted the effectiveness of Seacat.

As well as use in point defence against air attack, Seacat was justified as an anti missile against Styx missiles of the Warsaw Pact navies and Middle East and Asian clients of the Soviet Union. And as a 'large shell' for junk bashing and countering fast attack craft. It was also justified on its, 'ridiculous simplicity', and ease of maintenance, compared with the Mk 5 Twin Bofors and STAAG type mountings and as a weapon with great export potential and a good example of UK technological progress in line with the Sandys 1957 defence review and new broom. The missile was shown for the first time to the general public at the 1959 Farnborough Air Show. The first acceptance trials of the Seacat on a warship was in 1961 aboard HMS Decoy. The Seacat became the first operational guided missile to be fired by a warship of the Royal Navy. Later it was adopted by the Swedish Navy, making it the first British guided missile to be fired by a foreign navy.

Design features

The Seacat is a small, subsonic missile powered by a two-stage solid fuel rocket motor. It is steered in flight by four cruciformly arranged swept wings and is stabilised by four small tail fins. It is guided by command line-of-sight (CLOS) via a radio-link; i.e., flight commands are transmitted to it from a remote operator with both the missile and target in sight.

Variants

All Seacat variants used a common 4-rail, manually loaded, trainable launcher that incorporated the antennas for the radio command link. All that was required to fit the system to a ship was the installation of a launcher, the provision of a missile handling room and a suitable guidance system. Seacat was widely used in NATO and Commonwealth navies that purchased British equipment and has been used with a wide array of guidance systems. The four systems used by the Royal Navy are described below.

GWS-20

This - "Guided Weapon System 20" - was the initial system, which was intended to replace the twin 40 mm Bofors Mark V gun and its associated fire-control systems. The original director was based on the STD (Simple Tachymetric Director) and was entirely visual in operation. The target was acquired visually with the missile being guided, via a radio link, by the operator inputting commands on a joystick. Flares on the missile's tail fins aided identifying the missile. The more advanced CRBF (Close Range Blind Fire) director equipped with spin-scanning radar Type 262 for automatic target tracking could also be used.

HMS Eagle 's GWS-20 was trialled on board HMS Decoy, a Daring class destroyer, in 1961; it was subsequently removed. It was carried in active service by the Fearless class landing ships, the Type 12I Rothesay class frigates, the Type 61 AD frigates HMS Lincoln and HMS Salisbury, and the first group of County class escorts. HMS Kent and HMS London updated to GWS22 in the early 1970s. It was originally intended that all C class destroyers should receive GWS20 and the class were prepared accordingly. In the event only HMS Cavalier and HMS Caprice received it, in 1966 refits.

GWS-20 saw active service in the Falklands war on board the Fearless class and the Rothesay frigates HMS Plymouth and HMS Yarmouth, who retained the GWS-20 director when upgraded to GWS-22.

GWS-21

GWS-21 was the Seacat system associated with a modified Close Range Blind Fire analogue fire control director (CRBFD) with Type 262 radar. This offered manual radar-assisted (Dark Fire) tracking and guidance modes as well as 'eyeball' visual modes. It was carried as the design anti-aircraft weapon of the Type 81 Tribal class frigate, the 4 Battle class AD conversions, on the first four County class destroyers, HMNZS Otago and Taranaki and HMS Eagle. It was last used after sale to the Indonesian Navy and refit by Vospers Thornycroft in 1984 of, T81 Tartar, Ashanti and Gurkha.

GWS-22

GWS-22 was the Seacat system associated with the full MRS-3 fire control director with Type 903 radar and was the first ACLOS-capable (Automatic, Command Line-Of-Sight) Seacat. It was fitted to most of the Leander, Rothesay and County class escorts as they were refitted and modified in the 1970s, as well as the aircraft carrier HMS Hermes. It could operate in automatic radar-guided (Blindfire), manual radar-guided, manual CCTV-guided or, in an emergency, 'eyeball' guided modes. It saw active service in the Falklands onboard all these classes.

GWS-24

The final Royal Navy Seacat variant, this used the Italian Alenia Orion RTN-10X fire control system with Type 912 radar and was fitted only to the Type 21 frigate. This variant saw active service in the Falklands.

Tigercat

A land-based mobile version of Seacat based on a three-round, trailer-mounted launcher towed by a Land Rover, and a second trailer carrying the fire control equipment. Tigercat was used exclusively within HM Forces by 48 Squadron RAF Regiment between 1967 and 1978 with 12 Launcher Units, being replaced in service by Rapier. Tigercat were also operated by Argentina, a total of 7 fire units were captured by the British, some being ex RAF units bought by Argentina. India, Iran, Jordan, South Africa and Qatar. Argentina deployed it operationally during the Falklands conflict. No kills or any kind of success were initially believed to have been achieved by the marine-manned Tigercats, but according to more recent work a Tigercat missile scored a near-miss on 12 June, which scored substantial damage to RAF Harrier XW 919, spraying the local powerhouse roof with shrapnel and leaving the aircraft with category 4 damage.

Service

Seacat became obsolete due to increasing aircraft speed and the introduction of supersonic, sea-skimming anti-ship missiles. In these cases, the manually guided subsonic Seacat was totally unsuited to all but head-on interceptions and then only with adequate warning. A Seacat version was tested for intercepting targets flying at high speed near the water surface. This version used a radar altimeter, which kept the missile from being guided below a certain altitude above the surface and hence prevented the operator from flying the missile into the water. This version was never ordered.

Despite being obsolete, Seacat was still widely fielded by the Royal Navy during the Falklands war. Indeed, it was the sole anti-aircraft defence of many ships. However, unlike the modern and more complex Sea Dart and Sea Wolf systems, Seacat rarely misfired or refused to respond, in even the harshest conditions. It was capable of sustained action, which compensated for its lack of speed, range and accuracy; and, more importantly, it was available in large numbers.

After the Falklands conflict, a radical and urgent re-appraisal of anti-aircraft weaponry was undertaken by the Royal Navy. This saw Seacat rapidly removed from service and replaced by modern weapons systems such as Goalkeeper CIWS, more modern 20 mm and 30 mm anti-aircraft guns and new escorts carrying the Sea Wolf missile, including the vertical launch version.

The missiles were fitted to the four Swedish Östergötland-class destroyers, replacing three Bofors L/70 guns (a more modern and heavier variant than the Royal Navy's L/60) with a single launcher on each ship. The Östergötland-class destroyers, which were of late 1950s origin, were retired in the early 1980s.

Seacat was mounted on all six "River"-class destroyer escorts of the Royal Australian Navy and was removed from service when the final ship of this class was decommissioned in the late 1990s. In their final variant, fire control was provided by a GWS-21 guidance system supported by a Mk  44 fire control computer. Secondary firing positions based on visual tracking of the target through binoculars mounted on a syncro-feedback mount was also available. HMAS Torrens was the final ship to live fire the system prior to its removal from service; and this was also the only time three missiles were on the launcher and fired in sequence, resulting in one miss and two hits on towed targets.

Operators