The Office of Naval Research is looking for an alternative to batteries to power the Large Displacement Unmanned Underwater Vehicle for a period of days and months, according to an official.
An analysis of alternatives is ongoing for the LDUUV, as the Navy seeks to field a UUV that can handle bigger payloads while trying to solve the problem of how to power the vehicle in the most efficient way.
One of the main challenges is maintaining a neutral buoyancy with a large vehicle, and the energy section of the vehicle must be easily accessible to refuel it, said Maria Medeiros, ONR's program officer for the sea warfare and weapons department, in a Aug. 1 interview with Inside the Navy.
UUVs use batteries that provide a limited endurance of about 20 to 40 hours, and ONR must figure out how to not only put enough fuel on the LDUUV, but also have it carry an oxidizer in a confined section of the vehicle, she stated. "The traditional fuel-cell cars and portable power fuel cell applications, they utilize the oxygen in the air," Medieros said. "Underwater, obviously there is no air, so we have to carry the oxidizer so the fuel cells work."
This project is broken up into phases. The first phase is for 18 months, with an option phase lasting six months. The second phase lasts 24 months, she explained. The first phase includes a systems demonstration and finalizing the design for the second phase demonstration. The second phase includes full-scale system integration into a UUV energy section hull, a land-based test demonstration and developing standard operating procedures, according to the Aug. 4, 2011 broad agency announcement.
General Atomics, FuelCell Energy and Sierra Lobo were all recently awarded contracts for the first phase. For Phase I, the length of the mission is 46 days and ONR will travel to each site and evaluate progress. "A lot of these technologies have been demonstrated, but alone," Medeiros stated. "The challenge is to integrate these components together and [show they can] work efficiently."
ONR hopes to award two contracts for Phase II. In the second phase, the technologies will be integrated into the LDUUV and not only will the endurance be longer, but the energy needed will increase from 800 kilowatt hours to 1,800 kilowatt hours, she said. "The goal of the program is to demonstrate an effective capability gap that exists right now," Medieros said.
Naval Sea Systems Command began an LDUUV analysis of alternatives in mid-July. The materiel development decision was signed by the milestone decision authority on July 18, allowing the AOA to begin, Naval Sea Systems Command spokesman Chris Johnson wrote in a July 27 email.
"We expect the AOA to help the Navy determine the key metrics for desired LDUUV capabilities, and provide an analytical basis for deriving key performance parameters and other performance parameters for the LDUUV acquisition program," he said. "We anticipate that the AOA will evaluate several acquisition topics, including required LDUUV system attributes to achieve mission success for key scenarios, technical risks associated with the development and fielding [of the] LDUUV and cost-effectiveness analysis trades among system characteristics such as endurance, speed, depth, signature, autonomy and payload." The Navy anticipates wrapping up the AOA in the March 2013 time frame, Johnson added.
Likely mission sets include intelligence, surveillance and reconnaissance, as well as intelligence preparation of the operational environment, Capt. Duane Ashton, unmanned maritime systems program manager in the Littoral Combat Ship program executive office, told ITN in April. Also, the open architecture base would allow modules, payloads and even propulsion systems to be plugged in as needed for use off an LCS, a submarine or a pier.
Asked if the Navy would pursue different variants of the LDUUV, Ashton said the AOA would answer that question, but he hoped it would be limited to just one, or perhaps two if needed. "I could not afford 20 versions of this," he said. "So part of our analysis of alternatives is to look at that very question."