Editing November-class submarine (section)

==Description==

The November class were double-hulled submarines with streamlined stern fins and nine compartments (I – bow torpedo, II – living and battery, III – central station, IV – diesel-generator, V – reactor, VI – turbine, VII – electromechanic, VIII – living, IX – stern). Three compartments equipped with bulkheads to withstand 10&nbsp;atm pressure could be used as emergency shelters.

The November-class attack submarines were considerably noisier than diesel submarines and the early American nuclear-powered submarines, despite the streamlined torpedo-like hull, limited number of holes in the hull, special low-noise variable-pitch propellers, vibration dampening of main equipment, and antisonar coating of the hull (used for the first time on nuclear-powered submarines). Soviet reactors were superior to American ones in compactness and power-to-weight ratio, but the vibrations of Soviet reactors were much more pronounced. Novembers detected submarine targets during active service (for example, there were 42 detections in 1965 when regular cruises of Soviet nuclear-powered submarines began).{{Citation needed|date=May 2012}} The Soviet hydroacoustic equipment on the Novembers was not intended for submarine hunting, and had relatively limited capabilities.

The reliability of the first Soviet nuclear-powered submarines was relatively low because of the short service life of the steam generators in the main propulsion machinery, which caused an increase of the radioactivity level in the second loop of the reactor after several hundred hours of reactor operation. Machinery problems were the main reason why Project 627/627A submarines were not used during the [[Cuban Missile Crisis]] in autumn 1962.{{Citation needed|date=July 2010}} The reliability of the steam generators became better over the course of construction development, handling technical problems and training of crews, so Novembers began to frequently perform Arctic under-ice cruises and patrol missions to trace nuclear delivery vessels in Atlantic Ocean in the 1960s. Despite the common opinion about the dangers of radiation in the first Novembers, the background radiation levels in the compartments was usually normal because of relatively effective iron-water radiation protection of the reactor compartment and radiation monitoring.{{Citation needed|date=August 2010}}

The first submarine of the class (Project 627), K-3 ''Leninskiy Komsomol'' was first underway under nuclear power on 4 July 1958 and became also the first Soviet submarine to reach the [[North Pole]] in July 1962, four years after {{USS|Nautilus|SSN-571|6}}. Project 627 had much better performance specifications (for example, submerged speed and depth) than the world's first operational nuclear-powered submarine USS ''Nautilus''.{{Citation needed|date=October 2010}} The first commander of K-3 ''Leninskiy Komsomol'' was Captain 1st Rank L.G. Osipenko (future admiral and Hero of the Soviet Union).

All other Novembers except K-3 ''Leninskiy Komsomol'' belonged to modified project – '''project 627A'''. The main visual differences of project 627A were a bow sonar dome in the keel and a hydrophone antenna over the torpedo tubes. The Project P627A design armed with nuclear cruise missile system P-20 was developed in 1956–1957 but not finished, equipment and mechanisms were used for building the usual attack submarine of project 627A (submarine ''K-50'').

A single vessel, submarine ''K-27'', was built as '''project 645''' to use a pair of [[liquid metal-cooled reactor|liquid metal-cooled]] [[VT-1 reactor]]s. ''K-27'' was launched on 1 April 1962 and had some additional differences from Novembers: cone-shaped hull head, new antimagnetic strong steel alloys, somewhat different configuration of compartments, and a rapid loading mechanism for each torpedo tube. A liquid metal-cooled reactor had better efficiency than the water-cooled [[VM-A reactor]], but technical maintenance of liquid metal cooled reactors in naval base was much more complicated.{{Citation needed|date=August 2010}}