British frigates of the Cold War. Turbocouple sisters
British frigates of the Cold War. Turbocouple sisters
An extension of the Type 41 and Type 61 frigates featured in Special Issue 3/2016 of the Sea and Ships magazine were two more series of Royal Navy escort units known as the upgraded Types 12 and 12. They feature improved hydrodynamics, propulsion and equipment.
For studies on the British project of PDO blocks, carried out in the second half of the 40s, the "exemplary" target was submarines capable of reaching a speed of about 18 knots in a submerged position, with the simultaneous assumption that it could soon increase. Therefore, the Admiralty demanded that again the designed frigates were capable of a maximum speed of 25 knots with a power plant of 25 20 km and a range of 000 3000 nautical miles at a speed of 15 knots. These requirements were valid only until the end of 1947, by the beginning of the new year, there were significant changes in the approach of the Royal Navy to the PDO problem. According to his latest instructions, escort ships were to reach speeds 10 knots faster than enemy submarines. From here, after analyzes, it was found that 27 knots would be optimal for the new "hunters". Another important requirement of the Admiralty was the issue of flight range, the value of which increased from the previous 3000 to at least 4500 nautical miles at the same economic speed. It quickly became clear that the development of a steam turbine power plant that, on the one hand, was light and compact, and on the other hand, could generate the power needed to achieve 27 watts, while maintaining a fuel consumption that allowed 4500 mm of travel, would not be so simple. To make these demands more realistic, the Admiralty finally agreed to limit the economic speed to 12 knots (the lowest allowed for escorting convoys traveling at 10 knots).
Initially, work on the new PDO unit proceeded very slowly, due to the high priority given to converting World War II destroyers into the frigate role. The draft design was ready in February 1950. Work on the new frigates did not begin until the beginning of the blockade of West Berlin, which occurred on the night of June 23-24, 1948. In their project, it was decided to use elements borrowed from the previously described type 41/61 frigates, incl. low superstructure, artillery in the form of a two-seat Mk V universal gun in a 114 mm Mk VI turret (controlled by the Mk 6M fire control system), as well as 2 Mk 10 Limbo mortars installed in the aft "well". Radar equipment was to consist of type 277Q and 293Q radars. Later, two types 262 (for anti-aircraft fire at short distances) and type 275 (for anti-aircraft fire at long distances) were added to them. Sonar types 162, 170 and 174 (the latter was later replaced by the newer type 177) were to be included in the sonar equipment. It was also decided to install torpedo weapons. Initially, they were supposed to consist of 4 single permanently installed launchers with a reserve of 12 torpedoes. Later, these requirements were changed to 12 chambers, of which 8 (4 per board were supposed to be stationary launchers), and another 4, in the 2xII system, rotary.
The use of new turbo-steam power plants for propulsion had a negative impact on the weight and size separation. In order to be able to build it, the hull had to be enlarged, after many analyses, its length increased by 9,1 m and the width by 0,5 m. This change, although initially criticized for fear of rising prices, turned out to be a very good move, as swimming pool tests have shown that the lengthening of the hull improved the laminar flow of the water, further increasing the speed achieved (“long runs”). The new drive also made it necessary to install a classic chimney instead of inconspicuous diesel exhausts. The planned chimney was designed to withstand the blast of an atomic blast. Ultimately, however, practicality was prioritized over exorbitant demands, which is what forced it to be redesigned. It was lengthened and tilted more back. These changes brought tangible benefits, as fogging of the cabin was stopped, which significantly improved the working conditions of the watch crew.
