OVERVIEW: The TANGO-class aka Project 641B aka Som class is a 3-shaft, diesel powered long-range patrol submarine.

DETAILS:   The Tango submarine is a late second/early third generation conventional submarine intended to operate against both oceanic SLOCs and in an 'ambush' role against warships operating at chokepoints on the sea lanes. They were also reportedly deployed as escorts for DELTA SSBNs.

The TANGO is a double-hull design. It uses the same engineering plant as the earlier FOXTROT class submarine. Significant improvements over the FOXTROT class include a streamlined hull and a significant increase in battery capacity, range, and endurance. Additionally, the TANGO's diving depth was improved by increasing the thickness of the pressure hull. The TANGO incorporated increased automation, including the sonar being linked directly to the torpedo FCS, enabling rapid generation of targeting solutions. 

The TANGO also incorporated numerous quieting features over the earlier FOXTROT class. These included eliminating the noise-creating limber holes, adding an anti-sonar coating on the outer hull, and incorporating rafting of the machinery. The TANGO also featured shrouded screws, improving its cavitation properties. 

Some later units could use the SS-N-15.

Specifications:
       Displacement: 3,700 tons submerged; 3,000 tons surfaced.
       Speed: approximately 16 knots surfaced, 15.5 knots submerged
       Machinery: 3 x 2000 hp Kolumna 2D42 diesel engines, 3 electric motors 
	Armament:	6 bow tubes, 533 mm + 18 reloads or 36 AMD-1000 mines
       Endurance: 80 days; 14,000 @7 knts (surface) 400 nm @2.5 knots (submerged)
      Working Depth: 787 ft (240 m)      
      Operational Depth: 984 ft (300 m) 
       Maximum Depth:   1640 ft (500 m)  				 
       Complement: 62
       Hulls built:  18
       Period of Service:	 1972-2001

NOTES: IOC: 1972. Not exported. The Northern Fleet operated 15 TANGOs. One or two Northern Fleet units were typically deployed to the Mediterranean. Three additional units were operated by the Baltic Fleet. Units in class (in order): B-443, B-474, B-437 aka Magnitogorsk Komsomolets, B-498, B-515, B-519, B-290, B-303, B-146 aka Komsomolets of Kazakhstan, B-546, B-30, B-215, B-396 aka Novosibirsk Komsomolets, B-307, B-319 aka Komsomolets of Chuvashia, B-225, B-312, B-380 aka Gorky Komsomolets aka Holy Prince George.



SOURCES: Conway's All the World's Fighting Ships, 1947-1982. Part II: The Warsaw Pact and ; Polmar, Norman, and Kenneth J. Moore. Cold War Submarines: The Design and Construction of U.S. and Soviet Submarines. Lincoln: Potomac Books, 2004, page 201-203; Sword of the motherland historical Foundation. (n.d.).  https://www.russianwarrior.com/STMMain.htm?1979vecindex.htm&1 ; (n.d.)."Project 641B "Som" (NATO-"Tango"). https://www.deepstorm.ru/ ; Prezelin, Bernard. The Naval Institute Guide to Combat Fleets of the World, 1990-1991. US Naval Institute Press, 1990, pg. 587-88; Polmar, Norman, and Kenneth J. Moore. Cold War Submarines: The Design and Construction of U.S. and Soviet Submarines. Lincoln: Potomac Books, 2004 (Kindle edition), pp. 205 ; "The Tango Class Russia's Rubber Submarine." Navy General Board. Last modified June 5, 2021. https://www.navygeneralboard.com/the-tango-class-russias-rubber-submarine/; https://www.subsim.com/radioroom/showthread.php?t=229242 ; David bocquelet - Naval encyclopedia. "Soviet Cold War Submarines 1947-1991." Naval Encyclopedia. Accessed July 28, 2022. https://naval-encyclopedia.com/cold-war/ussr/submarines.php.



