Akula-class submarine
The Akula" class, Soviet designation Project 971 "Shchuka-B (, NATO reporting name Akula) are a series of nuclear-powered attack submarines (SSNs) first deployed by the Soviet Navy in 1986. There are four sub-classes or flights of Shchuka-B, consisting of the original seven Project 971 boats (codenamed "Akula I"), commissioned between 1984 and 1990; six Project 971Is (Improved "Akula"s), commissioned between 1991 and 2009; one Project 971U ("Akula II"), commissioned in 1995; and one Project 971M ("Akula III"), commissioned in 2001. The Russians call all of the submarines "Shchuka-B", regardless of modifications. Some  confusion may exist as the name "Akula" (, meaning "shark" in Russian) was used by the Soviets for a different class of submarines, the Project 941, which is known in the West as the . The Project 971 was named "Shchuka-B" by the Soviets but given the designation "Akula" by the West after the name of the lead ship, K-284. According to defense analyst Norman Polmar, the launch of the first submarine in 1985, "shook everyone [in the West] up", as Western intelligence agencies had not expected the Soviet Union to produce such a boat for another ten years. Design. The  Akula incorporates a double hull system composed of an inner pressure hull and an outer "light" hull. This allows more freedom in the design of the exterior hull shape, resulting in a submarine with more reserve buoyancy than its western analogs. The distinctive "bulb" or "can" located on top of the Akula's rudder houses its towed sonar array when retracted. Most "Akulas" have the wake detection system () (SOKS) hydrodynamic sensors, which detect changes in temperature and salinity. They are located on the leading edge of the sail, on the outer hull casing in front of the sail and on  the bottom of the hull forward of the sail. "Akulas" (excluding "Nerpa") are armed with four 533 mm torpedo tubes which can use Type 53 torpedoes or the RPK-2, RPK-6 missile, and four 650 mm torpedo tubes which can use Type 65 torpedoes or the RPK-7 missile. These torpedo tubes are arranged in two rows of four tubes each. The external tubes are mounted outside the pressure hull in one row, above the torpedo tubes, and can only be reloaded in port or with the assistance of a submarine tender. The 650 mm tubes can be fitted with liners to  use the 533 mm weaponry. The submarine is also able to use its torpedo tubes to deploy naval mines. The modernized versions, like "Vepr", will be equipped with the Kalibr cruise missiles. Versions. As with many Soviet/Russian craft, information on the status of the Akula-class submarines is sparse, at best. Information provided by sources varies widely. Project 971 ("Akula I"). Of the seven original "Akula"s, only three are known to still be in service. These boats are equipped with MGK-540 Skat-3 sonar system (NATO reporting name Shark Gill). The lead boat of the class, K-284 "Akula" was decommissioned  in 2001, apparently to help save money in the cash-strapped Russian Navy. K-322 "Kashalot" and K-480 "Bars" [currently "Ak Bars"] are in reserve. K-480 "Bars" was put into reserve in 1998, and was being dismantled in February 2010. "Pantera" returned to service in January 2008 after a comprehensive overhaul. All were retrofitted with the SOKS hydrodynamic sensors. All submarines before K-391 "Bratsk" have reactor coolant scoops that are similar to the ones of the SSBNs, long and tubular. "Bratsk" and subsequent submarines have reactor coolant scoops similar to the short ones on the Oscar IIs (the "Typhoon", "Akula" and  Oscar classes use the similar OK-650 reactor). Project 971 and 971I (Improved "Akula I"). The six "Akula"s of this class are all thought to be in service. They are quieter than the original "Akula"s. Sources also disagree as to whether construction of this class has been suspended, or if there are a further two units planned. Improved "Akula I" Hulls: K-328 "Leopard", K-461 "Volk", K-154 "Tigr", K-419 "Kuzbass", K-295 "Samara" and K-152 "Nerpa". These submarines are much quieter than early "Akula"-class submarines and all have the SOKS hydrodynamic sensors except "Leopard". The "Akula I" Improved submarines have six 533 mm  decoy launching tubes, as do subsequent submarines. They have a different arrangement of limber holes on the outer hull than "Akula Is". Submarines "Nerpa" and "Iribis" (not completed) have a different rescue chamber in the sail, which can be distinguished by the large dome on the top surface. Project 971U ("Akula II"). K-157 "Vepr" is the only completed "Akula II" (see the table below). The "Akula II" is longer and displaces about 700 tons (submerged displacement) more than the "Akula I". The added space was used for additional quieting measures. K-157 "Vepr" became the first Russian submarine that was quieter  than the latest U.S. attack submarines of that time, which was the improved (SSN 751 and later). Two of these submarines were used to build the SSBNs. Project 971M ("Akula III"). The K-335 "Gepard" is the 14th submarine of the class and the only completed "Akula III" (see the table below) built for the Russian Navy. It was the first submarine commissioned in the Russian Navy since the "Kursk" disaster, as a result, its commissioning ceremony was an important morale boost for the Russian Navy with President Vladimir Putin in attendance. There is no NATO classification for the "Akula  III". It is longer and has a larger displacement compared to the "Akula II", also it has an enlarged sail and a different towed-array dispenser on the vertical fin. Again, more noise reduction methods were employed. The "Gepard" was the most advanced Russian submarine before the submarines of the and class were commissioned. The Soviet advances in sound quieting were of considerable concern to the West, for acoustics was long considered the most significant advantage in U.S. submarine technology compared to the Soviets. In 1983–1984 the Japanese firm Toshiba sold sophisticated, nine axis milling equipment to the Soviets along  with the computer control systems, which were developed by Norwegian firm Kongsberg Vaapenfabrik. U.S Navy officials and Congressmen announced that this technology enabled the Soviet submarine builders to produce more accurate and quieter propellers. Due to the breakup of the Soviet Union in 1991, production of all "Akula"s slowed. The 1999–2000 edition of "Jane's Fighting Ships" incorrectly listed the first "Akula III" as "Viper" (the actual name is "Vepr", "wild boar" in Russian), commissioned on 25 November 1995. "Gepard" (Cheetah), was launched in 1999 and was commissioned 5 December 2001. Operational history. Between December 1995 and February 1996, submarine  Volk was deployed to the Mediterranean along the Russian aircraft carrier , where she monitored activities of several NATO submarines under Captain 1st rank S. V. Spravtsev. Between April and June 1996, "Tigr" was deployed in the Atlantic, where she detected a U.S. SSBN and tracked it on its combat patrol. On 23 July 1996, its commander, Captain 1st rank Alexey Burilichev, received a Hero of the Russian Federation award. In August 2009, the news media reported that two "Akula"-class submarines operated off the East Coast of the United States, with one of the submarines being identified as a Project 971  Shchuka-B type. U.S. military sources noted that this was the first known Russian submarine deployment to the western Atlantic since the end of the Cold War, raising concerns within U.S. military and intelligence communities. U.S. Northern Command confirmed that this 2009 "Akula"-class submarine deployment did occur. One of the boats was likely "Gepard" that finished a relatively lengthy combat patrol between June and September that year under the command of the Captain 1st rank Alexey Vyacheslavovich Dmitrov, who on 15 February 2012 was awarded a title Hero of the Russian Federation for courage shown at work. The other submarine  could have been "Tigr" under the command of Captain E. A. Petrov, given that she performed a combat patrol sometime between March and November 2009. It is unlikely that other submarines of the project 971 could have been present in the Atlantic that year. "Pantera" was in Severemorsk during summer, while "Vepr", "Leopard" and "Volk" did not report any kind of activity in that year (1-3 submarines of the project are usually active with the Northern Fleet at any given moment). In August 2012, the news media reported that another "Akula"-class submarine operated in the Gulf of Mexico purportedly  undetected for over a month, sparking controversy within U.S. military and political circles, with U.S. Senator John Cornyn of the Senate Armed Services Committee demanding details of this deployment from Admiral Jonathan W. Greenert, the Chief of Naval Operations. Most likely, this was "Tigr", as its commander Captain 1st rank Pavel Bulgakov received the Order of Courage on the Defender of the Fatherland Day on 22 February 2013. Section::::"Nerpa" 2008 accident. On 27 October 2008, it was reported that K-152 "Nerpa" of the Russian Pacific Fleet had begun her sea trials in the Sea of Japan before handover under a  lease agreement to the Indian Navy. On 8 November 2008, while conducting one of these trials, an accidental activation of the halon-based fire-extinguishing system took place in the fore section of the vessel. Within seconds the halon gas had displaced all breathable air from the compartment. As a result, 20 people (17 civilians and 3 seamen) were killed by asphyxiation. Dozens of others suffered freon-related injuries and were evacuated to an unknown port in Primorsky Krai. This was the worst accident in the Russian navy since the loss of the submarine K-141 "Kursk" in 2000. The submarine  itself did not sustain any serious damage and there was no release of radiation. Lease to India. Three hundred Indian Navy personnel were trained in Russia for the operation of the Akula II submarine "Nerpa". India has finalised a deal with Russia, in which at the end of the lease of these submarines, it has an option to buy them. The submarine is named INS "Chakra" as was the previous India-leased Soviet Charlie-I SSGN. "Chakra" was officially commissioned into the Indian Navy on April 4, 2012. Whereas the Russian Navy's Akula-II could be equipped with 28  nuclear-capable cruise missiles with a striking range of , the Indian version is reportedly armed with the -range Club-S nuclear-capable missiles. Missiles with ranges greater than cannot be exported due to arms control restrictions, since Russia is a signatory to the MTCR treaty. Russia said in December 2014 that it is ready to lease India more nuclear-powered submarines a day after President Vladimir Putin and Prime Minister Narendra Modi pledged to deepen defence ties. In January 2015, it was reported that India was involved in negotiations involving the leasing of the "Kashalot" and the "Iribis". An  agreement was reportedly reached in October 2016. On 7 March 2019, India and Russia signed a $3 billion deal for lease of another Akula-class nuclear-powered attack submarine. The submarine, dubbed as "Chakra III", should be delivered to the Indian Navy by 2025. In June 2021, "Nerpa" was reported in Singapore with Indian crew aboard and on its way back to Russia, despite one year remaining of the 10 year lease, commenced in April 2012. The stated reason was problems with maintenance of the nuclear reactors. Accordingly, the lease will not be prolonged after 2022, as initially expected