Leopard-class frigate
The Type 41 or Leopard class were a class of anti-aircraft defence frigates built for the Royal Navy and Indian Navy in the 1950s. The Type 41 and the Type 61 variant introduced diesel-electric propulsion into the Royal Navy for its long range, low fuel use, and fewer necessary crew and skilled artificers, compared with steam turbines, as well as for its less complex diesel engines.
Design
These ships were designed to provide anti-aircraft escorts to convoys and light fleet aircraft carriers of the Sydney and Virkant classes and act as light destroyers on detached duties; as a result they were not built for fleet carrier task force speed —28 knots for the Victorious and Audacious classes and made only. They were envisioned in late World War II and immediately after as part of the 1944 project for a common hull anti-submarine warfare, anti-air warfare, and A/D frigate, and the design of the Type 41 was completed by December 1947.Like the 1950 RAN Battle-class variant and the unbuilt 1942 two-turret RN G destroyer, which the 1944 common hull escort closely resembles, the Type 41 Leopard class used the latest twin semi-auto 4.5" Mk6 turrets. This meant that, unlike other post-war frigates, the Type 41 had a full destroyer armament of two twin 4.5" Mk6 gun turrets, giving them a more powerful armament than the Battle- or Weapon-class destroyers.
The first production orders were in the 1951/2 and 1952/3 programmes. In 1953 eleven additional Type 41s, also with cat names like Cougar and Cheetah, were planned, together with ten Type 61 or Salisbury-class frigates, with which they shared a common hull and machinery.
Distinct from the Type 61, the Type 41 radar fit also supported surface fighting, whereas the radar fit of the Type 61 A/D frigates was, when introduced, largely identical to the reconstructed Dido-class A/D cruiser Royalist. To that end, HMS Leopard carried navigation radar, the new type 992 for long-range surface target indication, and the type 960M for LRAW as compared to the Type 61's four dedicated LRAW systems: types 293, 977M, 960M and 982M.
An intended A/S version, the Type 11 class, was cancelled due to the low 25-knot top speed being insufficient for accompanying fast carrier task forces, particularly with HMS Eagle, the flagship, commissioned in 1951. However, in practice, frigates and destroyers moving at more than 25 knots create turbulence which blinds their own sonars and can only engage fast-moving subs by using a helicopter with its own sonar. Thus the Type 41s were still fitted with the best late-1950s RN sonars, types 170 and 174, but were equipped with only a minimal A/S mortar battery.
Through their diesel-electric propulsion the Type 41s achieved long range through their low fuel use. The Leopard class was also fitted with an early type of hydraulic stabiliser system consisting of two fins that could be extended outside the main hull, to port and starboard, from a compartment between the two engine rooms. Gyro controlled with a relatively simple control system, they proved very effective in use. During testing every three months at sea, the ship could be easily driven into a 20°+ roll from the manual control on the bridge. Prior warning had to be given over the ship's tannoy system before testing was carried out, to allow stowage of loose items. Slight reduction in top speed was also noticed when in use.
However, by 1955 success had been achieved, with difficulty and limitations, in developing new steam turbines giving 30-knot speed and the range to take convoys across the Atlantic, embodied in the Whitby-class Type 12 frigates. As a result, the orders for the new diesel-electric frigates were cancelled, changed to orders for Type 12, or sold to India.
Within a few years of the Type 41's introduction in the late 1950s they were regarded as obsolete for their intended function as anti-aircraft convoy escorts. This was emphasized when the planned replacement of the 4.5" guns with 3"/70 AA guns was abandoned due to cost and the view that AA guns were obsolete against jets and missiles. Adding power-ramming for the twin 4.5" guns, intended to boost the rate of fire from 14rpm to 24rpm, failed. Innovative additions of STAAG, CIWS mount, and replacement of the experimental version of the fast rotating 992 target indicators with the slower standard 993 were all abandoned. Only a short range 262 radar MRS1 provided secondary AA fire control for the main armament.
Service
In service the Leopard class were used mainly as patrol frigates, notably on the South American station, where their long range and impressive destroyer-like appearance were particularly advantageous. Operating out of Simonstown in South Africa, they in part replaced the Dido-class cruisers HMS Euralyus and Cleopatra usually deployed on these duties during 1946-1954. It was hoped a pair of Type 41 gunships with four twin-4.5" guns between them would be adequate to deter a single Russian Sverdlov cruiser, which British Naval Intelligence saw as having been in part conceived of to threaten the traditional trade from Buenos Aires to England. Later they were extensively used in the Far East during the 1963–68 confrontation with Indonesia over Borneo and Malaysia, for which all-gun-armed Type 41s were again well suited. In the 1970s they saw service on Cod War duties.In 1972 it was decided not to refit HMS Puma again, as purchasing the half-sister of the class, the former Black Star ordered by Ghana, and commissioning it as HMS Mermaid, would cost less than a Type 41 refit. HMS Leopard finished its service in the 1975–1976 Cod War, having given an Icelandic gunboat a 30-second warning that it would open fire with its 4.5" guns. HMS Lynx was the last of the class operational, in 1977 attending the Spithead fleet review. HMS Jaguar was reactivated from the standby squadron for the 3rd Cod War, but sprang too many leaks on the voyage to Iceland and instead returned to Chatham.
HMS Jaguar and HMS Lynx were sold to the Bangladesh Navy in 1978 and March 1982 respectively. Had they been retained a few more years they could have been ideal during the Falklands War for specialized bombardment and the air defence of ships unloading in San Carlos Water: the destroyers and frigates remaining in RN service in 1982 had only one gun turret, the new 4.5" Mk8 often jammed, and the few with the Lynx Mk8 twin-4.5", with 40-45 men required for each turret, rarely even test fired the guns. As it was, the Bengaldesh Navy found the Leopard-class satisfactory and useful for long life, the ships being active until they were retired in 2013.