The K.377 class (or zolotaya ruba, meaning "Golden Fish") nuclear attack submarine (SSN) was initiated in 1957 as a purpose built carrier battle group "interceptor." Designated Project 705, the Lyra was built to wait in port until offshore sensors detected the approach of enemy carrier battlegroups, at which time the crew would board the submarine and, vectored toward the approaching enemy fleet by ground controllers, make a high speed attack run using 53cm torpedoes. To meet these requirements, the submarine had to be fast, which in turn, required it to be small and powerful. To this end, everything was sacrificed in the name of reducing the hull's "wetted" area (that portion of the submarine in contact with the water), displaced weight and maximizing the its power output. To save on weight the reactor was designed to run automatically and sealed off from the rest of the ship by a single bulkhead. To increase power, a design cooled by liquid metal (sodium) was selected over a more conventional water cooled model. Because the Pr. 705 would not be used for extended patrols at sea, many of its systems were automated, and the crew was slashed to 29-43 officers. Lastly, in order to improve diving depth and reduce weight, a revolutionary titanium alloy was used in constructing the hull.
Unfortunately, the technology required to fabricate titanium on such a scale did not exist at the time and it was not until 1965 that the design was ready for production. Furthermore, by the time the Pr. 705 submarines were ready for production, the primary threat to the Soviet Union, and the whole reason for the class' existence, had shifted from the carrier battlegroup to the ballistic missile submarine. Nonetheless, production continued and eventually 7 submarines were built. Hated by the Soviet Navy as well as the crews aboard them, the 705's were so obsolete by the time they entered service that there was never any serious indication that they would ever be deployed. Because their automated systems were susceptible to damage by exposure to radiation the reactor systems were unreliable and it is believed that 4 of the 7 suffered reactor failures. Eventually the submarines were deemed to dangerous to be tolerated and all were pulled from service by 1995. Roughly equivalent to the American 1957 USS Seawolf (the only American submarine to use a liquid metal reactor) in design philosophy, by the time they were launched the Lyra I class submarines were hopelessly outclassed by current American SSNs.