Silent running (submarine)
Encyclopedia
Silent running is a stealth
mode of operation for naval submarines. The aim is to evade discovery by passive sonar
by eliminating superfluous noise: nonessential systems are shut down, the crew is urged to rest and refrain from making any unnecessary sound, and speed is greatly reduced to minimize propeller noise.
The screws have a characteristic RPM band in which no cavitation noise arises. Since this rotation speed is usually relatively low, the first electric submarines had special "silent running" engines designed for optimum performance at reduced speed. These required less active cooling (further reducing noise), and were generally equipped with "slip-bearings" rather than ball-bearings. These engines were also acoustically decoupled from the hull, as they employed belt transmission rather than direct coupling to the propeller shaft.
Nuclear submarines can run even more quietly, at very low speeds only, by turning off active reactor cooling during silent running. The reactor is then only cooled by natural convection of the water.
This article is based on a translation of the German-language Wikipedia page.
Stealth technology
Stealth technology also termed LO technology is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, to make them less visible to radar, infrared, sonar and other detection...
mode of operation for naval submarines. The aim is to evade discovery by passive sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
by eliminating superfluous noise: nonessential systems are shut down, the crew is urged to rest and refrain from making any unnecessary sound, and speed is greatly reduced to minimize propeller noise.
The screws have a characteristic RPM band in which no cavitation noise arises. Since this rotation speed is usually relatively low, the first electric submarines had special "silent running" engines designed for optimum performance at reduced speed. These required less active cooling (further reducing noise), and were generally equipped with "slip-bearings" rather than ball-bearings. These engines were also acoustically decoupled from the hull, as they employed belt transmission rather than direct coupling to the propeller shaft.
Nuclear submarines can run even more quietly, at very low speeds only, by turning off active reactor cooling during silent running. The reactor is then only cooled by natural convection of the water.
This article is based on a translation of the German-language Wikipedia page.