AUVSI: Navy seeks long-endurance power for UUVs

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At AUVSI's Unmanned Systems North America 2010, Chief of Naval Operations Admiral Gary Roughead said the navy would invest heavily during the next five years to produce ship-safe, long-endurance power for its unmanned underwater vehicles.

Sensor development for such UUVs has gone well, he said, but power systems had not kept up and it was time for the Navy to "tackle the fundamental questions of endurance". In other briefings, the Office of Naval Research (booth 1027) says that when it comes to UUVs, developing energy sources that allow multi-week missions is its greatest technology need.

Some of the ways the Navy plans to meet that need will be funded under a recent broad agency announcement (BAA) for long-endurance undersea propulsion. What the Navy must do, the BAA says, is move away from battery-only systems, which just don't have enough juice. "Current and future anticipated technologies based solely on high energy-density batteries will not provide adequate endurance for future Naval UUV missions," a Navy document says. "Solutions beyond battery-only technology are required."

admiral gary roughead, jim mcdonald/choice photography
 © Jim McDonald/Choice Photography
Adm Gary Roughead says it is time for the Navy to "tackle the fundamental questions of endurance"

Although Roughead would not rule out the use of nuclear power in the future, it is not part of the plan, either.

"Nuclear options will not be considered for this effort," the BAA says.

ENERGY HULL

The Navy is seeking a system that will fit in a 76.2cm (30in) space, have an energy density of 300-600 watt hours per litre and last for at least 30h. Open systems, or those that emit gas or liquid, will be considered, along with closed systems that do not.

Phase one of the program is expected to last up to 18 months and each task order will total about $3.5 million. Selection for that phase is scheduled for 15 August. In phase two, expected to last up to 30 months, the companies selected to move ahead will be given a full-scale UUV energy hull to integrate their systems into and conduct land-based exercises to show they work. ONR says about $8 million is available for each phase two award, although if there is not enough money to fund all the companies that met the criteria, the Navy will conduct a down-select.

According to Richard Carlin, ONR's director for sea warfare and weapons, ONR received "multiple responses" to the BAA, from industry, non-profits and educational entities. "There were a variety of technology solutions proposed," he says.

LONG-RANGE MISSIONS

ONR also plans to seek ideas for powering the Large Displacement Unmanned Underwater Vehicle Innovative Naval Prototype (LDUUV), a program to develop a long-endurance UUV that would be launched and recovered from piers rather than ships. It would be capable of moving across open ocean and conducting long-range missions.

"This system will enable the extension of Navy platform sensing capability over the horizon and extend its influence," a Navy document says. "The creation of this UUV is intended to act as a significant force multiplier for the US Navy and will help close warfighter gaps in a cost-effective manner."

Stand down, nuclear adherents. Nuclear options won't be considered for this effort, either.

Respondents will have more room to work with, as the energy section length will be up to 304cm (120in), but the required duration is longer, too. ONR wants the LDUUV systems to provide at least 46 days of endurance, with 70 days being the objective.

Phase one of the contract is expected to last 18 months, with a six-month option, phase two would last up to 24 months.

In another BAA, the US Navy is seeking operating efficiencies for LDUUVs to increase their endurance. Some of the technologies may overlap with the request for energy systems, the navy notes.

Others could include technologies to reduce the power draw of the core systems and systems to boost reliability, such as smart components that can predict part failure.

In phase two of this request, the selected systems will take to the water in a full-scale UUV prototype for "a pier-launched mission expected to last no less than 70 days".

The goal is to drop the core system power requirements by 75% while maintaining that 70-day mission goal.