Compared to the US Navy’s small and agile Skipjack Class submarines, the Soviet’s first generation Project 627 NOVEMBER Class nuclear powered attack submarines were generally considered an inferior design. They were plagued with reactor problems.
The NOVEMBER Class SSN was a large submarine with an ultra-modern streamlined bow and sail married to an older style 'knife' stern.
In the early 1960s Russian engineers started to design the follow-on attack submarines which would close the gap or exceed the American boats. Rather than stealth, they focused their attention on speed. Several innovative solutions were designed into the Project 673 boat. It was to be built from titanium alloys which are both lighter and stronger than steel and do not corrode. The nuclear reactor was to be a high-power lead-bismuth liquid-metal-cooled nuclear plant which had the feature of solidifying in case of a leak. This was both an effective safety feature and an Achilles’ heal as the reactor could not be brought back into operation if this occurred.
The Project 673 submarine was designed as an interceptor boat, to be kept in port and sent out in the event of an intruding NATO submarine. It was therefore designed for speed.
The most obvious external feature was that the design lacked a sail. Instead, a retractable tower acted as the bridge when the submarine was on the surface. This configuration reduced drag and made the boat more agile.
Internally the design was very elegant with the forward pressure hull split into three decks. The control room was on the upper deck, the torpedo room in the middle and the crew berthing in the bottom. The lack of sail meant that the control room could be in the bow of the boat.
The project 673 design was too advanced for its time and the second generation of Soviet attack submarines were destined to be more modest, at least in design terms.
Length 66.26 m
Displacement: 1500/2200 tons
Speed: 25 kt cuising, 40 kt max, 5 kt silent
Propulsion: 155 MW ‘OK 550’ liquid metal cooled reactor (LMR) delivering 40,000 hp, driving 4m diameter 5-blade prop . 2 x pop-out outboard auxiliary motors
Construction: double hull, titanium alloy
Depth: 600 m operating, 800 m max, 1300 m crush.
Crew: 35, incl. 10 officers
Armament: 6 x 533mm (21”) torpedo tubes with 18 torpedoes (including up to 8 missiles) br> Endurance: 30-50 days.
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Legacy: ALFA Class
Many design concepts from the Project 673 were put into practice in the Project 705K ALFA Class which entered service in the 1970s. Capable of an incredible 41 kt, the ALFA was widely held as the fastest submarine in the world (although actually the larger PAPA Class was slightly faster). Although still compact, the ALFA was about 25% longer and featured a streamlined sail with escape capsule. The ALFAs were incredibly automated with the tiny all-officer 31 man crew only venturing into the bow or stern sections for maintenance.
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