Sea Cat missile

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Sea Cat was a British short-range surface to air missile system intended to replace the ubiquitous Bofors 40 mm gun aboard warships of all sizes. It was the worlds first operational shipboard point-defence missile system and was designed so that the Bofors guns could be replaced with minimum modification to the recipient vessel using (originally) existing fire-control systems.

Contents

1 History
2 Design Features
3 Variants

3.1 GWS-20
3.2 GWS-21
3.3 GWS-22
3.4 GWS-24
3.5 Tigercat

4 Service
5 See also

History

Sea Cat 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 itself was based on the Shorts Green Light prototype, itself a development of the Australian Malkara anti-tank missile. It replaced the Orange Nell development programme for a lighter weapon than the enormous Sea Slug missile.

Design Features

Sea Cat is a small, subsonic missile powered by a 2-stage solid fuel rocket motor. It is steered in flight by four swept, cruciformly arranged 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 Sea Cat variants used a common 4-rail, manually-loaded, trainable launcher that incorporated the antennae 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. Sea Cat 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 was the initial system, and 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 inputing 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.

GWS-20 was trialled on board the Daring class destroyer, and was subsequently removed. It was carried in active service by, (amongst others) Fearless class landing ships and Type 81 Tribal, updated Type 12 Whitby, Type 12I Rothesay and (originally) County class escorts. It was originally intended that all C class destroyers should receive it 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 onboard 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 Sea Cat system associated with a modified MRS-3 (Medium Range System) analogue fire control director with Type 904 radar (based on the USN Mk.56 system). This offered manual radar-assisted (Dark Fire) tracking and guidance modes as well as CCTV and 'eyeball' visual modes. It was carried as the design anti-aircraft weapon of the Type 12M Leander class frigate and on the modified Tiger class helicopter cruisers HMS Tiger and HMS Blake.

Sea Cat on HMNZS Wellington Leander class frigate

GWS-22

GWS-22 was the Sea Cat 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) Sea Cat. 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 Sea Cat 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 3-round, trailer-mounted launcher towed by a Land Rover carrying the fire control equipment. Tigercat was used exclusively within HM Forces by No.48 Squadron of the RAF Regiment between 1967 and 1978, being replaced in service by Rapier. Tigercat was also operated by, amongst others, Argentina, who deployed it operationally during the Falklands conflict. No kills were achieved and a number of units were captured by British forces.

Service

In its day, Sea Cat was an innovative and world-beating weapon. However, it rapidly fell behind with increasing aircraft speed and the introduction of supersonic, sea-skimming anti-ship missiles. In these cases, as it was subsonic, it was totally unsuited to all but head-on interceptions with adequate warning and response time.

Sea Cat was still widely fielded by the Royal Navy during the Falklands war, despite being obsolete, and was the sole anti-aircraft defence of many ships. However, unlike the modern and complicated Sea Dart and Sea Wolf systems, Sea Cat 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. Ships firing Sea Cat made claims on only one confirmed "kill" of Argentine aircraft (a Dagger at 21 May) from over 80 launches. That aircraft over the taskforce were engaged with every available weapon makes it difficult to assign many kills to individual ships or weapons.

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

The missiles where fitted to the four Swedish Östergötland class Destroyers replacing 3 Bofors L/70 guns (a more modern and heavier variant then the Royal Navy's L/60) with a single launcher on each ship. The Östergötland class destroyers of late 1950's origin where retired in the early 80's.