General-purpose Frigates (as built)
The Leander class was the UK’s most successful frigate design. This design combined operational flexibility with excellent sea-keeping in affordable ships that were adaptable to new requirements. Leander s were very active with Royal Navy aircraft carrier task forces and in other operations. This section covers the RN ships as built. A separate section covers these ships as modernized.
In the late 1950s the naval construction directorate added air conditioning and a helicopter facility to a Rothesay (Type 12) design intended for New Zealand. Features brought forward from the Type 12 design included the hull shape, the engineering plant, and part of the armament. Elimination of deck-mounted tubes for the canceled Mk 20E heavy torpedo permitted a larger superstructure while still leaving paths on deck for underway replenishment. In a new seawater-compensating fuel system, fuel tanks once emptied of black oil could be refilled with seawater to maintain proper trim. This eliminated the Type 12's separate water-ballast trim tanks and permitted the relocation of heavy equipment in their stead low in the ship. Both diesel electrical generators were relocated from the forecastle to a lower location forward of the boiler room. Their exhaust vented through ducts in the foremast, which was stepped further forward than in the Type 12.
With the resulting increased stability margin and the additional internal space, the designers added a large operations center, the helicopter facility, variable-depth sonar (VDS), a long-range air-search radar, more-capable communications, a centralized cafeteria, active stabilizer fins, and provision for Sea Cat missiles for close-range air defense.
The Admiralty, greatly liking this design, ordered conversion to it of an authorized Type 61 frigate and of three Type 12 frigates on the building ways. These became the first four Leanders. The Leander class never had a frigate type number, in particular not “Type 12M.” Type-numbering of new designs was functionally irrelevant after the RN abandoned the mobilization strategy in 1954.
During the 10-year construction program the installed armament varied, as the tables show. The Canadian-developed combination of variable-depth sonar and a ship-based helicopter was intended to equalize the fight against fast submarines. With VDS, the helicopter, and the improved operations room, Leanders could engage submarines at longer range, which improved the probability for detecting submarines and gave more time to engage. Seven of the first 10 ships mounted imported Canadian SQS-504 VDS as Sonar Type 199 and four later ships mounted British-built licensed copies. Other ships carried the hoisting gear for the VDS but never received transducers.
The first ten ships retained the Y-100 steam propulsion plant of the Type 12 and Type 14 frigates. The next six, Phoebe through Danae , had a Y-136 improved propulsion plant. The final ten ships mounted the same armament as the preceding ships but featured a Y-160 automated propulsion plant and a wider hull for modernization.
The RN built 26 Leanders and other navies built 18. This total of 44 set the post-1945 record for construction to one design among frigates and larger warships outside the United States and Russia. Elaborate “finish” was arguably wasteful but perhaps good appearance contributed to foreign naval orders for Leanders. Exclusive of weapons, in the mid-1960s construction cost about the same per ton as for the contemporary USN Knox-class (DE/FF 1052) frigates. The Leander program reportedly bolstered American political enthusiasm in the 1960s and 1970s for frigates, although the U.S. Navy designs had no technical connection with the British ships. Newer warships derived from the Leander design have included HMS Bristol, the RN Type 22 frigates, and the Indian Godaviri and Bramhaputra classes.
The Leander design introduced little new technology: no gas turbines, long-range missiles, computers, or automatic guns. If this cautious choice was a gamble, the RN won the bet because these technologies proved largely experimental until about 1970. The RN then began to induct the Leander s for mid-life modernization. The first three Leanders to be modernized were withdrawn from service during 1970–71 even while the final four of the class were being built largely to the then-obsolescent original design.
High inflation during the 1970s greatly increased the financial cost of mid-life modernization. The 1981 defence review halted additional major conversions. That left the final five Leander s with their obsolescent as-built armament for the remainders of their RN careers.
2,930 tons full load
2 550 PSI boilers, 30,000 SHP (22.5 MW), 2 shafts, 28 knots
Hanger and deck for 1 Wasp HAS Mk 1 helicopter (retired March 1988). Wasp weapons: AS-12 missile, Mk 43/44 torpedo, depth charges.
Search radar: Type 965 long-range air search, Type 993 surface search, Type 978 piloting. Gun direction system Mk 5.
Note: All air-defense weapons could also fire in surface action. The Type 965 air-search radar, a major advance over the Type 12 design, was jocularly called 'the key,' as in a clockwork-driven toy.
First 7 : 2 4.5" guns (Mk 6 mount), Medium-Range System Mk 3 director (MRS Mk 3; radar Type 903). 2 40mm Mk 9 guns.
Others : 1 Sea Cat SAM, GWS22 director (radar Type 904; except Naiad had manual GWS20 only). 2 4.5" guns (Mk 6 mount), MRS Mk 3. 2 20mm guns.
Note : The Leanders were far in advance of others navies, including the USN, in mounting guided missiles for point defense.
First 22 : 1 Mk 10 mortar. Sonar: Type 177 scanning sonar; Type 199 VDS on 11; Type 170 attack sonar; Type 162 sea floor tracing sonar. Decoy: Type 182.
Last 4 : 1 Mk 10 mortar. Sonar: Type 184M multi-function (active scanning, torpedo warning, Doppler); Type 170; Type 162. Decoy: Type 182.
First group (4) :Electronic attack: 4.5" chaff shells. ESM: UA-3 radar warning. ComInt: FH-4 HF/DF.
Second group (15) :Electronic attack: Corvus chaff after 1967; 4.5” chaff shells; Type 667 jammer. ESM: UA-8, UA-9 radar warning. ComInt: FH-4 HF/DF.
Third group (7) :Electronic attack: Corvus chaff; 4.5” chaff shells; Type 668 jammer. ESM: UA-8, UA-9 radar warning. ComInt: FH-5 HF/DF or (final 2) UA-13 UHF/DF. FH-5 and UA-13 used the same electronics but different antennas. FH-5 used the FH-4 wire-cube antenna and UA-13 used a large 'cone-and-arrow' antenna.
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