Boeing expects to return its A160 Hummingbird to flight this month, more than a year after it crashed in the final moments of a 12h flight that set a new endurance record for an unmanned helicopter. Resumption of flight testing will allow Boeing Advanced Systems to pursue its goal of demonstrating more than 20h endurance.
“We will return to flight in October pending a successful review,” says Darryl Davis, vice-president of advanced precision engagement and mobility systems. Changes resulting from the crash, which was caused by component failure, include design modifications making the unmanned rotorcraft more robust and reliable, he says.
The A160 has a variable-rpm “optimum-speed” rigid rotor that offers efficient low-power loiter and long endurance. Rigid blades allow the rotor to be slowed to half speed in the loiter, giving an endurance of more than 20h at 15,000ft (4,600m) with a payload of more than 135kg (300lb), rivalling fixed-wing unmanned air vehicles.
Started by the US Defense Advanced Research Projects Agency, and acquired by Boeing in 2004, the A160 programme is now also funded by the US Special Operations Command (SOCOM) as an advanced concept technology demonstration. “We are anxious to mature the technology,” says Davis.
The A160 will be powered by a six-cylinder Subaru car engine, but Boeing is already building the first of seven Pratt & Whitney Canada PW207 turboshaft-powered vehicles for a SOCOM demonstration to take place during the second quarter of next year.
Davis says plans for a diesel-powered variant with a more than 30h endurance have “been pushed off into the future”, as the turboshaft will provide basing flexibility by burning the same kerosene fuel as other US military helicopters. Boeing’s Phantom Works is working on a diesel engine that can operate reliably up to the A160’s 30,000ft transit altitude, but has a “long way to go”, he says.