UAVs

Boeing has begun flight testing the X-48B blended wing body research aircraft to validate flight-control software that could be used in a full-size version of the flying-wing aircraft.

The 6.4m (21ft)-span unmanned aircraft, one of two built by the UK's Cranfield Aerospace, made a 31min first flight from the lakebed at NASA Dryden Flight Research Center at Edwards AFB in California.

The 225kg (500lb) aircraft stayed in the middle of its speed and altitude range for the flight, reaching 65-70kt (120-130km/h) and 8,000ft (2,400m), says X-48B chief engineer Norm Princen. Five to eight flights are planned in slats-extended configuration, and the same again with slats retracted, before Boeing begins exploring the unstable aircraft's low-speed flying characteristics, including stalls, he says. Up to 25 flights are planned by year-end under the Boeing-funded project.

The X-48B is dynamically scaled to respond in the same way as a full-size aircraft, only three times faster because of its small size. "We could take the flight-control software and use it in the next-step BWB directly," says Princen. Boeing and NASA are discussing the possibility of a larger demonstrator, he says.

"It is NASA's intent to restart BWB research and we are discussing the next step," says Princen. "We are not sure whether it will involve these two aircraft or a different vehicle, but there is a lot of interest in the concept and it benefits. Whether there is an intermediate demonstrator vehicle will depend on the end application." The flying wing promises substantially reduced cruise drag and fuel consumption.

Boeing emphasises that a commercial passenger BWB is not within its current 20-year market outlook, but the company is looking at a long-range, high-capacity military multipurpose aircraft that could be available in 15-20 years. Boeing Phantom Works has also studied the potential for a commercial freighter version with operators including FedEx Express.