The Defense Advanced Research Projects Agency (DARPA) plans in 2015 to test the energy subsystem of a flight-like ground demonstrator as part of its Vulture ultra-persistent, high-altitude, long-endurance (HALE) unmanned aerial vehicle (UAV) program, according to Vulture’s program manager.

Vulture program manager Chris Schulz said recently DARPA is focusing on Vulture’s solar collection (photovoltaics) and energy subsystems (solid fuel cells) because these technology areas are critical for persistent HALE flights and are the least mature. DARPA seeks to develop critical enabling technologies for an airborne payload to remain on-station and uninterrupted for more than five years while performing intelligence, surveillance and reconnaissance (ISR) and communications missions over an area of interest, according to a statement.

“Solving energy management challenges for persistent HALE flights of five years or longer could benefit a number of future HALE aircraft applications and should reduce risk for development of future very long-endurance aircraft programs,” Schulz said in an e-mail.

Vulture was once a full-scale flight demonstration effort, but DARPA last year restructured contractor Boeing’s [BA] deal to build its solar-powered UAV flight demonstrator, known as SolarEagle, over these technology maturation concerns. Boeing was awarded an $89 million contract in 2010 to develop and fly a solar-powered UAV flight demonstrator by 2014.

Though plans for the SolarEagle demonstrator have been shelved indefinitely, Boeing spokeswoman Deborah VanNierop said recently this refined approach makes better sense in the use of funding and provides a more concentrated focus on these technologies in this environment of constrained defense budgets.

Schulz said DARPA recently completed the Solid Oxide Fuel Cell 1,000 hour degradation testing and is now moving toward integration of the Solid Oxide Module. Schulz didn’t specify when Solid Oxide Module integration was expected to take place.

Despite the re-focusing of its Vulture contract with Boeing, Schulz said DARPA is not seeking an alternate performer. Schulz said, including 2013, Vulture has a $146.2 million budget.

Vulture’s advanced energy storage system technologies ultimately could enable a re-taskable, persistent pseudo-satellite capability in an aircraft package. Such a system would combine key benefits of an aircraft (flexibility and responsiveness, sensor resolution, reduced transmit/receive power and affordability) with the benefits of space assets (on-station persistence, no logistics tail, energy independence, fleet size and absence of in-country footprint), according to a DARPA statement.