Autolycus (submarine detector)

[3] Named after the mythical Greek, Autolycus, who took part in the search for the Golden Fleece, it was developed by the British during the early Cold War period.

[4] Until the end of the Second World War, submarines spent the majority of the time on the surface, powered by their diesel engines.

When Nazi Germany invaded and occupied the Netherlands in 1940 they also captured the latest Dutch O 21-class submarines equipped with snorkels, which the Germans then copied and started to use from 1943 onwards.

In the Soviet Union, the four Type XXIs that were assigned to them by the Potsdam Agreement formed the basis for their Whiskey class.

In the 1950s, the Fleet Air Arm were flying in the North Sea and the GIUK gap for patrol and potentially anti-submarine warfare in search of Whiskey, Zulu and Foxtrot submarines.

Early Mk II versions of Autolycus suffered from calibration difficulties in high humidity and stopped working altogether in rain.

When an exhaust plume was detected, the aircraft would begin to fly a tracking pattern of progressively shorter zig-zags.

As the track was narrowed down, the aircraft would switch sensors to a more precise method, such as centimetric radar or dropping sonobuoys before potentially closing for an attack.

Nimrod was fitted with Autolycus, but this legacy equipment was no longer considered to be a first-line technique and so it was not integrated into the new tactical display system, based on an Elliott 920 digital computer.

[10] As these did not need to snorkel and did not produce diesel exhaust they were effectively undetectable by either the Shackleton's Autolycus or its ASV Mk 13 radar.