Artist's impression of "Blue Wolf"
The range of underwater vehicles is limited by the amount of energy available for propulsion and the power required for a given underwater speed. Underwater propulsive power varies roughly with the cube of speed, and energy sources are practically limited by safety and certification requirements.
Currently, this means that for a given speed and range (endurance) envelope and a minimum volume for payloads and electronics, vehicle size is proportional to the energy needed for a given mission. Designers can modify this envelope by improving the vehicle’s energy efficiency – by reducing hydrodynamic drag, improving lift-to-drag performance, or by improving the volumetric energy density of the energy sources. However, in a fixed-size vehicle, the volume and weight needed for systems to reduce drag or improve lift-to-drag generally reduces the volume and weight available for energy.
DARPA’s Blue Wolf program focuses on development of novel energy and hydrodynamic lift and drag reduction technologies, which will then be tested at sea. Dynamic lift and drag reduction include such possible design techniques as dynamic lift from winglets, body shaping and coatings. Hybrid energy systems are expected to be explored as well, including thermal and/or electrochemical, and energy-harvesting with multiple energy sources--all to improve energy efficiency measured in Watt hours per mile. DARPA researchers further plan to explore thermal and electric sources like fuel cells and batteries that can fit in an undersea vehicle system module.
Officials of the Naval Undersea Warfare Center (NUWC) in Keyport, Wash., recently announced they have awarded Blue Wolf contracts to the Boeing Co. and Lockheed Martin Corp. NUWC officials awarded a $2.5 million DARPA Blue Wolf contract to the Boeing Defense, Space & Security segment in Huntington Beach, Calif., and a $2.5 million DARPA Blue Wolf contract to the Lockheed Martin Mission Systems and Training segment in Riviera Beach, Fla.
Boeing and Lockheed Martin thus join the Charles Stark Draper Laboratory in Cambridge, Mass., which won a $3.7 million Blue Wolf contract in August, and Applied Physical Sciences (APS) Corp. in Groton, Conn., which won a $3.1 million Blue Wolf contract last July.
The Blue Wolf program will use a “reference architecture” to achieve rapid system integration and certification for at-sea demonstrations. The reference architecture defines the hardware and software relationships between functional modules within the Blue Wolf platform, and will evolve throughout the program. DARPA’s Blue Wolf reference design consists of a 21-inch-diameter right circular cylinder vehicle with volume and weight set aside for guidance, control, electronic systems, and a payload section. Each module section will have a vehicle DC power bus, a vehicle network bus (Controller Area Network [CAN] and FlexRay), and instrumentation / testing bus (Ethernet). The vehicle will use an electric drive and conventional fin control.