C4iSR: Maritime

Sweden set to test ‘Double Stirling’ AIP plant

17 June 2019

Saab Kockums and Sweden's Defence Materiel Administration (FMV) are preparing to begin testing of a prototype 'Double Stirling' air-independent propulsion (AIP) system aimed at a nascent Swedish future submarine programme.

The 150 kW module, which occupies the same footprint as the original 75 kW Type A19 Gotland-class installation, represents the fifth generation of Stirling cycle AIP to be developed for Swedish submarines.

Saab Kockums' Stirling engines burn oxygen (stored in liquid form [LOX] in cryogenic tanks) and diesel fuel in a pressurised combustion chamber to generate electricity for propulsion or for charging batteries within a conventional diesel-electric plant. The company has iteratively developed Stirling AIP technology since testing a prototype plant that went to sea in 1989; the latest Mk 4 version was refitted to HMS Gotland and HMS Uppland as part of the Gotland-class mid-life update (MLU).

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