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Russian Navy

Project 705 Lira
Alfa class
Attack Submarine (Nuclear Powered)

The Project 705 Alfa class constitued the world's fastest and deepest diving submarines of their time. The submarine featured a high power-to-weight reactor to increase the power-to-weight and volume ratios of her propulsion plant, the first use of titanium for the hull, extensive automation, and advanced drag-reduction configuration.

Project 705 originated in a 1957 requirement for a 1500 ton "interceptor" submarine capable of a speed of 40 knots that would sortie to attack American aircraft carriers. Using a titanium alloy allowed the thickness and weight of the hull to be reduced, producing a remarkably small, very fast submarine. Around 1963 the desing was substantially revised, with the displacement was increased to 2,300 tons, the number of internal compartments increased from three to six and the size of the crew was doubled.

Construction of the first Project 661 prototype unit began around 1965, which was completed at the Sudomekh shipyard in Leningrad in 1972. The prototype was rebuilt after trials, and subsequently broken up around 1974. Made from titanium alloys, it could accelerate to a speed of 44.7 knots, a record which will hardly be beaten in the near future.

Although a much-feared design in the West, these concerns were prompted by grossly exaggerated accounts of the boat's capabilities and an assumption that they represented the main thrust of Soviet submarine development. The fast, deep diving nuclear submarine threat proved a false alarm, but they provoked massive investments in ASW weapons by the US Navy, and resulting in dramatic improvements in the Mk. 46 and Mk. 48 torpedoes that apparently culminated in the 63-knot ADCAP torpedo.

Extremely noisy at high speeds, the noise levels of the Alfa at lower speeds were generally similar to that of other Soviet SSNs. Though extremely fast, the boats were unreliable, poorly armed and with sensors that were unique, hard to maintain and frequently defective. Two different models of liquid metal (probably lead-bismuth) reactors were used. The four boats built at the Admiralty shipyard used the BM-40A reactor with two separate steam loops and circulating pumps. The boats built at Severodvinsk [Project 705K] used the OK-550 with branched first-loop lines and triple circulating loops and pumps.

The reactors required a heater to prevent the liquid metal coolant from solidifying. In 1972 the reactor on K-377 suffered a casualty during sea trials and the metal coolant "froze" destroying the reactor. In 1982 the reactor on K.316 was destroyed when the heating system was accidentally turned off. A special facility was constructed the submarines were moored to supply superheated steam to heat the liquid metal when the reactors were shut down. External heating proved unsatisfactory, and the reactors had to be kept running even while the submarines were in port.

Series production of the Project 705 boats began in the mid-1970s, and the program ended in 1983 with the sixth production unit. Eventually four of the seven Project 705s were lost due to reactor failures. One boat was retired by the end of 1987, and four others were decommissioned in 1990-1992. At least one [and possibly two] was modified with VM-4 pressurized water reactors from Project 671B and used for test activities prior to being decommissioned in 1995.


Displacement (tons): 2,310-2,900 tons Surfaced
3,800-4,320 tons Submerged
Speed (kts): 14 knots surfaced
43-45 knots submerged
Endurance: 1,175 full power hours
30-50 days stores endurance
Operating Depth 1,150-2,000 feet Maximum Safe Depth
1,400-3,900 feet Never-Exceed Depth
1,700-?,??? feet Crush Depth
Dimensions (m): 79.5-81.4 meters long
9.5 meters beam
6.9-7.6 meters draft
Propulsion: 1 liquid-metal nuclear reactors
(155 MWt Type: OK-550 or BM-40A)
[2 units re-engined with VM-4 reactor from Project 671B]
2 steam turbines; 40-47,000 shp
1 5 bladed propeller
Crew: 31-45
  • 21 81R (SS-N-15) or
  • 12 Vodopad (SS-N-16)
  • Torpedoes: 6 533mm bow TT
  • 18 53-65K, SET-65 torpedoes or
  • 20 VA-111 torpedoes or
  • 21 SS-N-15/81R or
  • 24 mines
  • Systems:
  • Topol MRK.50 [Snoop Tray] Surface Search radar
  • Sozh Navigation system radar
  • MG-21 Rosa Underwater communications
  • Molniya Satellite communications
  • Vint & Tissa Communications antennas
  • Accord Combat direction system
  • Leningrad-705 Fire control system
  • Okean active/passive Sonar
  • MG-24 Luch mine detection sonar
  • Bukhta ESM/ECM
  • Yenisei Sonar intercept receiver
  • Khrom-KM IFF
  • Class Listing

    #numberName Laid Down Launched Comm. Stricken
    1K-377 SY 196NOR1965196719721974ex K.71
    test ship 1974
    reactor accident in sea trial
    2K-316 SY 196NOR---------- 19741979---------- 1990-93 in reserve
    1995- dismantled
    3K-373 SY 196NOR---------- 19761978---------- 1990-93 in reserve
    in storage in Zapadnaya Litsa
    4K-123 SY 402NOR01/**/1975 12/26/1977 ---------- 1995project 705K lead ship
    built at SV12/1978 operational
    08/08/1982 reactor accident
    1990 new reactor installed
    1991 recommissioned as test ship
    5K-432 SY 402NOR---------- 19781982---------- project 705K
    1990-93 in reserve
    1994-95 dismantled
    6K-463 SY 196NOR---------- 197819821986 1986- reactor accident and decommissioned
    project 671B conversion (new PWR)
    1990-93 in reserve
    7K-493 SY 402NOR---------- 1981198311/1997 project 705K
    project 671B conversion (new PWR)
    1990-93 in reserve

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