The Kilo class is an attack submarine of Soviet origin. The name Kilo is a NATO reporting name for what is called the Project 877 Paltus submarine in Russia. The Kilo designation also applies to the improved Project 636 Vashavyanka. The Kilo was designed in the 1970’s to replace the Tango class. The Kilo is a great improvement over the previous Tango class but is considered fairly basic compared to contemporary designs in the West. The new Lada class is destined to complement the Kilo in Russian service.

The Kilo is a diesel electric attack submarine. The major improvement over the earlier Tango class is the shape of its hull. The layout is conventional with the torpedo tubes are at the front, the crew compartment and conning tower in the middle and the engine compartment at the rear. The hull is highly compartmentalized and an excess buoyancy of 32 percent allows the Kilo to survive multiple punctures of the hull. Vertical and horizontal control fins are fitted at the rear. There is no upper vertical fin.

The Kilo class has six 533mm torpedo tubes and up to 18 torpedoes can be carried. Various models of the Type 53 torpedo can be launched, including the 53-65. Later versions are also able to launch wire guided torpedoes such as the TEST-71 and USET-80. Instead of torpedoes up to 24 mines can also be carried. In Russian service a MANPADS system is carried.

The Kilo is equipped with the MGK-400 (NATO Shark Gill) sonar system that includes the MG-519 Arfa (NATO Mouse Roar) sonar. An MRP-25 (NATO Snoop Tray) surface search radar is also fitted. The improved Type 636 features an improved version of all electronics.

The Kilo is fitted with two diesel engines that charge the batteries and provide propulsion under normal circumstances. When submerged below snorting depth an electrical motor is used. A single fixed pitch propeller provides propulsion. The maximum speed is 10 knots at the surface and 17 knots submerged. The maximum depth is 300 m, although a maximum of 240 m is maintained for safety reasons.

The main use of the Kilo class was the USSR and currently is Russia. The Kilo class was exported to several Russian allies with India and China being the major foreign users. The Lada class attack submarine will complement the Kilo in Russian service. However, the Kilo is expected to remain in production for export.