Contrarotating electric drive for attack submarines

This paper addresses certain issues relating to the viability of contrarota ting (CR) electric drive for attack submarines. Topics include CR propulsio n's potential benefits, electric drive advantages, and combining contrarota tion with electric drive engine room concepts. CR propellers provide propul sive coefficient (PC) increases compared to open-type and performance-enhan ced single propellers. The maximum submarine propulsion plant power capacit y could therefore be reduced with this PC increase, potentially resulting i n a smaller, lighter propulsion plant This paper concludes, however, that c ontrarotation shows no propulsion plant weight savings against electric dri ve attack submarines with performance enhanced single propeller designs. We ight improvements in the power generation plant and certain steam plant and electric plant systems are offset by weight increases from the additional shafting and bearing requirements for the CR shaft. Contrarotation is curre ntly more advantageous for nonnuclear ships, where significant fuel savings are achievable with its higher PC.