The 4 - 95 Stirling Engine For Underwater Application

The 4 - 95 Stirling engine was originally developed by United Stirling in the 1970's and more than 50 engines have been manufactured and used in different applications. The engine was used as a baseline engine in the Automotive Stirling Engine program managed by NASA and in solar programs together with JPL, Advanco and McDonnel Douglas. In 1988 United Stirling was acquired by Kockums Marine AB, which is one of the world leading submarine builder, and the Stirling engine development was concentrated on engines with air-independent combustion systems for underwater application. Parallel to the development of the 4 - 275 engine, which is in operation in two submarines, Kockums Marine is also developing a prototype energy system based on the 4 - 95 engine for use in an Unmanned Underwater Vehicle (UUV). This paper describes the conversion of the 4 - 95 engine to an underwater engine with a combustor that burns diesel fuel with pure oxygen. Measured performance and experience from an endurance test will also be reported.