The Project 685 (Plavnik) class (known in the west by its NATO reporting name Mike) was a class of nuclear attack submarines of the Soviet Union in the cold war period. Only one vessel of this class was built: the K-278 Komsomolets. This unit was commissioned in 1984. The submarine sank on 7 April 1989 because of an accident. It has been reported that another submarine of this class was being built, but this unit was apparently never completed.

The Mike class was designed as an advanced nuclear attack submarine, in which new technologies were to be tested. The inner pressure hull was made of titanium, a very strong metal, which made it possible to dive much deeper than other military submarines. It was originally believed in the west that the mike class had a special liquid metal nuclear reactor. This turned out to be a misunderstanding. The Soviet Union later revealed that the submarine was powered by a conventional pressurized water reactor.

Specifications

• Estimated displacement:
  • 4,400-5,750 tons surfaced
  • 6,400-8,000 tons submerged
• Dimensions:
  • Length: 117.5 meters
  • Beam: 10.7 meters
  • Draft: 8-9 meters
• Estimated speed: 26-30 knots submerged
• Maximum operating depth: at least 3300 feet (about 1000 meters)
• Crew: 64-68
• Propulsion: a Single 190 MW OK-650 b-3 pressurized water reactor that powered two steam turbines. One propeller.
• Armament: 6 21-inch (533mm) torpedo tubes. Unknown number of torpedoes and cruise missiles.
• Electronics:
  • Snoop Head surface search radar
  • Shark Gill low-frequency active sonar
  • Bald Eagle EW suite