Aurora Flight Sciences plans to build conventional- and hydrogen-fuelled versions of its Orion long-endurance unmanned air vehicle. The company is building two hydrogen-fuelled technology demonstrators for the US Army, but is negotiating a contract with the US Air Force to complete the first of these with conventional power.

In early July, Aurora received the first tranche of US Army funding under a $27.7 million contract to demonstrate the Orion high-altitude, long-loiter (HALL) UAV. Powered by a Ford car engine modified by Boeing to burn hydrogen, the aircraft is designed to fly at 65,000ft (20,000m) for 100h.

Aurora president John Langford says the US Air Force Research Laboratory plans to provide an additional $3 million in funding to complete one of the two Orions with an unmodified gasoline engine and without the 2.74m-diameter vacuum-jacketed hydrogen tank, with the goal of demonstrating four to eight days endurance at 20,000-30,000ft. "Their interest is very long endurance at lower altitude. They don't need the hybrid engine," he says.

Paced by funding, the hydrogen-fuelled Orion HALL is expected to fly in 2009, but the conventionally powered version "could fly as early as late 2008", says Langford.

The tail for the first aircraft is under construction at Aurora's Columbus, Mississippi plant and tooling is complete for the 39.6m-span wing, with proof-loading testing planned for year-end. "We are waiting to see which fuselage to build," he says.

Boeing teamed with Aurora, Langford says, to use the Orion as a proof-of-principle demonstrator for a larger twin-engined hydrogen-fuelled UAV with an endurance of more than seven days at 65,000ft.

Full-power, long-duration testing of the Boeing-modified engine is under way at Aurora's Manassas, Virginia altitude facility, but the flight-design turbochargers have yet to be fabricated and tested, he says.

Langford says the Orion is in a "fundamentally different class" to Northrop Grumman's RQ-4 Global Hawk UAV because it is designed for extreme endurance with a payload of just 180kg (400lb). "Orion is designed to stay in one place for a very long time," he adds. The initial application is expected to be ballistic-missile defence.

The US Army plans technology demonstrations involving both the Orion HALL and Aerovironment's hydrogen fuel-cell-powered Global Observer. "HALL started out as an insurance policy for the High Altitude Airship," says Langford. "Now it's turning into a competition between HALL and Global Observer. We are comparable in size and performance and both use liquid hydrogen for long endurance and high altitude."

Source: Flight International