Soviet M-class submarine

The M-class submarines, also Malyutka-class (Малютка; baby or little one), were a class of small, single-, or 1½-hulled submarines built in the Soviet Union and used during World War II. The submarines were built in sections so they could easily be transported by rail. The production was centered in the Gorky Shipyard on the Volga River, after which the sections were railed to Leningrad for assembly and fitting out. This was the first use of welding on Soviet submarines.

1930s to 40s
Submarines of this class were in four series: VI, VI-bis, XII, XV. Constructions of VI and VI-bis series were almost equal. Series XII in fact was re-developed project with equal tactical characteristics. First series were powered by one diesel engine and one electric motor. Series XV had developed separately too and had improved characteristics, such as main ballast in light hull and two shafts. These vessels were mainly used in the Black Sea Fleet and the Baltic Fleet.

Although being quite a good design, only limited results were obtained and losses were heavy with 33 submarines sunk between 1941 and 1945. By 1945, some 111 M-class submarines had been completed, with another 30 XV-series being completed between 1945 and 1947.

Cold war
Two submarines of the early series of this class, along with two Soviet S class submarine, (S-52 and S-53) and two Shchuka class submarines (under lease, S-121 and S-123) were handed to People's Liberation Army Navy in June, 1954, thus becoming the foundation of the submarine force of the People's Republic of China. Both the M and S class submarines were sold to China, and subsequently, two more M-XV series of this class submarines, M-278 and M-279 were also sold to China a few years later. Those purchased by China received Chinese names, and the two leased S class submarine did not. The four M class submarines bought by China were named as National Defense # 21, 22, 23 (ex M-278) and 24 (ex M-279) respectively.

Modern times
An M-class submarine was discovered near Tallinn in May 2012. The submarine is located in the Tallinn Bay between the islands of Aegna and Naissaar, at an approximate depth of 65 to 66 meters. It's believed to be the M-216, which was intentionally sunk in the area in 1962 for training purposes. Divers have confirmed that many components, including the periscope, are missing. It's also believed that the training exercise may have been ordered as a result of several deadly submarine accidents in the 1950s. One such accident happened near Paldiski, where the entire crew died as a failure of the rescue operation.

Versions

 * Series VI: 30 submarines were constructed between 1932 and 1934
 * Series VI-bis: 19 submarines were constructed between 1934 and 1936) were 37.5 m long and displaced 202 tons submerged (161 tons surfaced). They were built in four sections.
 * Series XII: 45 submarines were constructed between 1936 and 1941. These were 44.5 m long, displaced 258 tons submerged (206 tons surfaced) and were built in six sections.
 * Series XV: 4 submarines were constructed during World War II and 53 after. These were 53.0 m long, displaced 420 tons submerged (350 tons surfaced) and were built in seven sections.

Both series VI and VI-bis were constructed by A. N. Asafov. Serie XII was made by P. I. Serdyuk, serie XV was created by F. F. Polushkin.