Russia’s P-750B Small Attack Submarine Design By Malakhit Design Bureau
The United Shipbuilding Corporation displayed at Army-2020 forum a scale model of the new Serval-class P-750B submarine, the Independent Military Review writes.
Xavier Vavasseur
Story by TASS Russian news agency
It is distinguished by more details than the submarine presented at the navy show in St. Petersburg last year. A part of the skin was withdrawn for the visitors to see the constructive specifics of the submarine and the changes introduced by Malakhit Design Bureau from July to December 2019 when the final concept was specified.
Serval P-750B has a displacement of 1400 tons and is equipped with an air-independent (anaerobic) power plant. It is a prospective submarine with numerous advanced solutions and technologies. The innovative approach of Malakhit manifested itself in the conceptual project completed in early 2020. 3D methods were used to calculate hydro dynamic characteristics and properly place equipment at an early state of the design.
Now it is necessary to specify the main technical solutions. Pipelines and cables are to be laid. 3D modeling will simplify the job. Construction materials, including metal alloys and composites are to be specified for the hull and the interior.
Serval is distinguished from all Russian non-nuclear subs by a gas turbine which replaced the classical diesel generator and a battery to power the electric engine. The idea is not new, but so far nobody succeeded to implement it although gas turbines are broadly used on surface warships.
The advantages of a gas turbine include its compact size, a high specific power and excellent acceleration rate. Modern gas turbines have a high resource. They are expensive in production, but can decrease life cycle costs.
Malakhit paid specific attention to safe operation. The power plant uses exhaust gasses enriched with oxygen instead of the atmospheric air. They are to be cooled and purified by the so-called Dewar vessels. P-750B power plant is rated as air-independent.
The submarine has a propulsion electric motor of 2500 HP (three-day underwater navigation with the battery) and a pair of diesel gas turbines of 450 KW each. They provide a speed of 10-12 knots.
The turbines operate in two regimes. The first one is for surfaced and the second one is for submerged position. The power plant consumes atmospheric air in the former case and liquid oxygen from cryogenic storage of Dewar vessels in the latter case. They freeze the exhaust gasses and there is no need to discharge them into the atmosphere. P-750B with a displacement of 1400 tons can sail 1200 miles underwater at an economical speed of four knots and maximum depth of 300 meters.
P-750B is a small displacement multirole submarine for coastal operations. The main weapons include torpedo and cruise missile launchers. The sub will interact with unmanned underwater craft.
The innovative solutions include replaceable modular payload: weapons, self-defense means, groups of underwater propulsion means and unmanned vehicles. The payload will be carried outside the solid hull. The concept opens new capabilities, as the payload will change before the sortie according to the missions.
P-750B complements previous Malakhit designs of Piranha small coastal submarines (Piranha-M, Piranha-T, Piranha-T1, P-550E, P-650E and others) with a displacement of 220 — 1450 tons. They defend coastal and sea borders by covert patrol and destroy single warships and submarines by torpedoes. The submarines can lay mines and strike at coastal targets. They can engage in reconnaissance and provide guidance to the fleet and aviation. Some Piranha submarines can engage in special operations and carry 6-8 combat divers.
The submarines of Malakhit have highly automatic controls. P-650E sub with a displacement of 720 tons (full displacement of 870 tons) has a nine-man crew. P-750B with a displacement of 1400 tons has a crew of 18-20 people.
P-750B differs from P-650E by a longer cruising range without surfacing, a higher speed and powerful arms, including Kalibr missiles (CLUB-S export option).
Over 30 years ago, the Soviet Navy received MC-520 Piranha subversion submarine of project 865. It had a titanium hull and could operate in shallow and coastal waters at a depth of 10-200 meters. It could carry a pair of 400mm torpedoes or mines, however, the main mission was not related to strikes and mining of seaports. Piranha was designed to deliver combat swimmers with weapons and evacuate them after the mission.
The design began in 1974. The rough design was approved in 1981 and project documentation was finalized two years later. The construction began in 1984.
The 30-meter long submarine of project 865 had a displacement of 220 tons. The diesel generator of 160 KW and propulsion electric engine of 65 KW developed a speed of seven knots. Autonomous navigation was ten days and the cruising range was close to a thousand miles.
Besides a three-man crew, Piranha could carry six combat swimmers. They left the submarine through a docking chamber. The noise was decreased due to resin coating of the outside hull and the placement of the diesel generator, fans and compressors on a separate shock-absorbing platform.
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