Alfa-class submarine

The Alfa class, Soviet designation Project 705 Lira (Лира, meaning "Lyre", NATO reporting name Alfa), was a class of nuclear-powered attack submarines in service with the Soviet Navy from 1971 into the early 1990s, with one serving later with the Russian Navy until 1996. They were among the fastest military submarines ever built, with only the prototype submarine (NATO reporting name Papa-class) exceeding them in submerged speed. The Project 705 submarines had a unique design among other submarines. In addition to the revolutionary use of titanium for its hull, it used a powerful lead-bismuth cooled reactor as a power source, which greatly reduced the size of the reactor compared to conventional designs, thus reducing the overall size of the submarine, and allowing for very high speeds. However, it also meant that the reactor had a short lifetime and had to be kept warm when it was not being used. As a result, the submarines were used as interceptors, mostly kept in port ready for a high-speed dash into the North Atlantic. Project 705 was first proposed in 1957 by M. G. Rusanov and the initial design work led by Rusanov began in May 1960 in Leningrad with design task assigned to SKB-143, one of the two predecessors (the other being TsKB-16) of the Malakhit Design Bureau, which would eventually become one of the three Soviet/Russian submarine design centers, along with Rubin Design Bureau and Lazurit Central Design Bureau. The project was highly innovative in order to meet demanding requirements: sufficient speed to successfully pursue any ship; the ability to avoid anti-submarine weapons and to ensure success in underwater combat; low detectability, in particular to airborne MAD arrays, and also especially to active sonars; minimal displacement; and minimal crew complement. A special titanium alloy hull would be used to create a small, low drag, 1,500 ton, six compartment vessel capable of very high speeds (in excess of ) and deep diving. The submarine would operate as an interceptor, staying in harbor or on patrol route and then racing out to reach an approaching fleet.