S-Class (Srednyaya)

History: The S-class or Srednyaya (Russian: "medium") submarines were part of the Soviet Navy's underwater fleet during World War II. Unofficially nicknamed Stalinets (Russian: Cталинец, "follower of Stalin"; not to be confused with the submarine L-class L-2 Stalinets of 1931), boats of this class were the most successful and achieved the most significant victories among all Soviet submarines. In all, they sank 82,770 gross register tons (GRT) of merchant shipping and seven warships, which accounts for about one-third of all tonnage sunk by Soviet submarines during the war.

Instead of German engines, domestically produced 1D turbo-diesels were installed. Unlike their foreign counterparts, they had (for the same power) slightly higher speeds and were non-reversible. To accommodate turbocompressors and other additional systems, exhaust manifolds were enlarged and various subsystems completely redesigned. In addition, domestically produced batteries were used. The open bridge was redesigned after requests from the crews, returning to traditional closed type. Later in the war boats were equipped with a Burun-M radio director, and the radios received an upgrade. Some boats were also equipped with periscope aerials, allowing the use of radio at periscope depths, and an ASDIC was mounted on most of the boats, significantly increasing patrolling and fire efficiency.

From Wikipedia

Type: Submarine

Primary Country: The Soviet Union, officially the Union of Soviet Socialist Republics, was a socialist state in Eurasia that existed from 1922 to 1991. Nominally a union of multiple equal national Soviet republics, its government and economy were highly centralized.