OVERVIEW: The Improved KILO class SSK (Project 636M) is a single shaft, medium endurance, diesel electric powered attack submarine.

DETAILS:   These attack submarines are mainly intended for anti-shipping and anti-submarine operations in relatively shallow waters. The Project 636 is an improvement over the earlier Project 877 Kilo SSK, featuring a longer pressurized hull, an automated targeting system, and more powerful diesel generators. The acoustic signature of the submarine was reduced by reducing the main propulsion shaft speed. The Improved Kilo 636 twice as quiet as the 877EKM.  Endurance was also increased. 

The KILO uses a teardrop shaped hull to reduce water resistance. The submarine has six watertight compartments and can survive having one compartment and two ballast tanks flooded.  The bow planes are positioned close to the midship to improve the performance of the sonar. To reduce the submarine’s acoustic signature, the flooding ports have been removed from the forebody. It also has a new gas-freeing system, and the hull is covered with anechoic tiles to reduce the risk of detection.

The propulsion plant consists of two Type 4-2DL42M diesel generator sets that power an electric motor. Only the electric motor is connected to the single shaft with one seven-bladed propeller. The power plant can propel the submarine up to 10 knots on the surface and 17 knots submerged. In addition, two small auxiliary motors generating 150Kw are fitted and a low powered electric motor of 95KW to run economically and slow speed operations up to 6 knots in ultra-quite mode. While submerged Project 877 class submarines can travel up to 400 nautical miles at a speed of 3 knots if the air conditioning system is not turned on. Two battery groups with each 120 cells provide 9,700 kWh at 100 Amp.

Type 636 is fitted with the MGK-400EM digital sonar. This provides detection of submarine and surface ship targets in sonar listening mode, echo-ranging in a ±30° sector of the target relative bearing, telephone and telegraph communication in both long and short-range modes, detection of underwater sound signals and determination of the signal bearing. The sonar is 2.5 times as sensitive as that carried by the earlier Project 877EKM boats.

The vessels can be fitted with the Klub-S (SS-N-27) cruise missile system, which fires the 3M-54E1 anti-ship missile, providing enhanced engagement capability against AEGIS-protected surface ships and land targets.

Specifications:

       Displacement: 2,450 tons surfaced; 3,670 tons submerged.
       Speed: 11 knots surfaced, 19 knots submerged
       Machinery: One 7400 shp electric, 2 1500 KW generators. 1 190 shp 		  		  auxilliary motor for low speed/quiet operations, 2 102 shp 		  		  reserve motors. 
       Endurance: 45 days; 7,500 nm surfaced @ 7 knts; 400nm @3 knts submerged
       Operational Depth: 240-250 m
       Maximum Depth:     300m	(crush depth)			 
       Complement: 52

            

NOTES: IOC: 1998 (Russia).  
  
 
 
SOURCES:  China_SCS_Info. (2019, April 22). Vietnamese navy kilo submarines. Medium. https://medium.com/indo-pacific-geomill/vietnamese-navy-kilo-submarines-77ce5dc97b0b ;Kilo class patrol submarine | military-today.com. (n.d.). MILITARY TODAY - Everything About Modern Warfare. https://www.military-today.com/navy/kilo_class.htm; Project 877 (Kilo) class. (n.d.). Weaponsystems.net. https://old.weaponsystems.net/weaponsystem/GG01%20-%20Kilo%20class%20(Project%20877).html; SSK kilo class (Type 877EKM). (2020, December 2). Naval Technology | Naval Defence News & Views Updated Daily. https://www.naval-technology.com/projects/kilo877/ ; Project 636 Varshavyanka class. (n.d.). Weaponsystems.net. https://weaponsystems.net/system/659-Project+636+Varshavyanka+class