Asymmetric Propulsion Systems Enhance Capabilities of Long-Range Underwater Vehicles

Unmanned Underwater Vehicles (UUVs) will play a key role in addressing the scalability required to build enduring advantages through integrated deterrence by providing resilient platforms with enhanced Intelligence, Surveillance, and Reconnaissance (ISR) and Anti-Submarine Warfare (ASW) capabilities. For UUVs, propulsion is the most power-consuming subsystem, and it is the largest noise source that may give away the presence of a UUV or adversely affect a UUV’s passive acoustic sensing abilities.  Asymmetric Propulsion Systems (APS) are a revolutionary advancement in UUV propulsion. APS provides both thrust and maneuverability from a single motor driving a single-bladed propeller. It works by varying the blade speed as a function of position to generate asymmetric thrust to steer. Single-bladed propellers can be 12% more efficient than traditional multi-bladed propellers. APS removes the need for fins, which can constitute 10% of total vehicle drag for streamlined UUVs. APS also enables station keeping and low-speed maneuverability not typically possible in streamlined UUVs.  ARMADA will enhance ISR/ASW capabilities in the undersea domain by integrating its APS onto the Tethys UUV which Saab recently licensed from MBARI. In Phase I, we will pay down risk and determine technical feasibility by establishing a performance baseline between an unmodified Tethys UUV and a Tethys with APS through both direct measurements of thrust and power and simulation of vehicle drag and stability with and without fins. These will be used to quantify the predicted improvements to mission duration and range with APS. Phase I efforts will also establish preliminary system specifications with regard to mechanical and electrical design layout, motor and motor control parameters and algorithms, and hardware component identification.  APS and Tethys will create a next-generation ISR/ASW platform providing days of additional mission time on top of an already impressive month of endurance, lower detectability as well as improved passive acoustic sensing, resilience through simplicity, and enhanced maneuverability. ARMADA leads a world-class team with WHOI in Phase I, MBARI support and ECM’s industry-leading motor design in Phase II, and the support of Saab as a future customer.