Air independent power systems for autonomous submarines

United Stirling AB (USAB), the world leader in Stirling external combustion engine development and Kockums AB are jointly testing in a full scale submarine test section a new 100 kW Stirling engine, the V4-275R, for the Royal Swedish Navy. The engine is integrated with a liquid oxygen storage and a closed cycle combustion system is provided for underwater propulsion. The successful development of a pressurized combustion system using diesel fuel and oxygen for the Stirling engine has lead to the next stage - a contract for installation of two V4-275R engines in a large, manned diver lock-out submarine, the SAGA I. This 500 ton commercial prototype, developed in France jointly by COMEX and CNEXO, is to be completed by 1986. It will demonstrate the "all-underwater" solution for various undersea tasks. Missions of up to 25 days submerged will be possible. The Swedish Navy intend to continue their Stirling program and a system for testing on naval submarines has been contracted.