The U.S. Defense Advanced Research Projects Agency (Darpa) and its developer reported this month that a small unmanned aircraft powered by a heavy-fuel engine flew for 56 hours without refueling, setting an apparent flight record for its subclass. Vanilla Aircraft, based at Falls Church in Virginia, is developing the VA001 for military communications and intelligence, surveillance and reconnaissance (ISR) missions as well as commercial remote-sensing applications.

Testers flew the VA001 from the New Mexico State University Unmanned Air Systems Flight Test Center near Las Cruces International Airport in New Mexico, beginning the morning of November 30 through the afternoon of December 2. Towed by a truck on takeoff and powered by a four-cycle engine and pusher propeller, the airplane flew at an altitude of between 6,500 feet and 7,500 feet msl, at an average speed of 57 knots.

A representative of the National Aeronautic Association, which verifies aviation records, certified the flight as achieving the world duration record for a combustion-powered UAV in the 50 kg-to-500 kg (110 pound-to-1,102 pound) subclass, according to the January 3 announcement. Plans called for a 120-hour mission, but the flight “was ended early due to forecasted severe icing and range restrictions,” Vanilla Aircraft said. “The airplane landed with enough JP-8 fuel on board for an additional 90 hours of flying.”

First flown in February 2015, the VA001 is designed to carry a 30-pound payload at 15,000 feet for up to 10 days without refueling. It has a 36-foot wing mounted above its fuselage, and a maximum gross takeoff weight of 600 pounds.

“The VA001 has transformational potential, providing a scalable aerial system solution without increasing personnel or operating costs,” said Neil Boertlein, Vanilla Aircraft co-founder and chief engineer. “The ability of a low-cost platform to provide persistent surveillance, battlefield pattern of life, or aerial mesh network relay, in a responsive and robust manner, and without forward basing, does not currently exist.”

For the record-setting flight, the VA001 carried real and simulated payloads totaling 20 pounds. Included were a communications relay provided by the Naval Air Systems Command (Navair) that “operated continuously throughout the flight to demonstrate functionality out to the maximum range,” and a NASA-supplied multispectral imaging payload to demonstrate remote sensing for Earth science and agricultural applications.

Technology investments made by the Department of Defense’s Rapid Reaction Technology Office and Darpa-funded efforts through Navair supported the flight.

“This record-breaking flight demonstrated the feasibility of designing a low-cost UAV able to take off from one side of a continent, fly to the other, perform its duties for a week, and come back—all on the same tank of fuel,” said Jean-Charles Ledé, Darpa’s program manager. “This capability would help extend the footprint of small units by providing scalable, persistent UAV-based communications and ISR coverage without forward basing, thereby reducing personnel and operating costs.”

Vanilla Aircraft plans to attempt a 120-hour flight again “soon,” and to conduct an operational demonstration with a larger optical payload.