The design, which is thought to be highly fuel efficient and offer longer range, could someday become the universal standard. But first comes several more years of tests.
NASA said today that its experimental X-48C hybrid wing-body airplane took flight for the first time.
A remotely powered prototype that's housed at NASA's Dryden Flight Research Center at Edwards Air Force Base in California's Mojave Desert, the X-48C is thought to be the future of efficient, long-haul aviation.
The plane is known as a hybrid wing-body because it's essentially a cross between a flying-wing design and a conventional plane. NASA and its partners in the U.S. Air Force, Boeing, and Cranfield Aerospace are confident the aircraft will offer users long-term fuel efficiency, fuel capacity, and noise reduction benefits.
Though today's first flight, at Edwards, heralds the beginning of the X-48C's time in the sky, the team behind it has been flying its precursor, the X-48B, since 2007. Both planes are 8.5 percent scale models of an eventual full-size plane, and have a wingspan of a little more than 20 feet and a weight of about 500 pounds. The B version was a blended-wing design that had three engines and winglet vertical tails. By comparison, the X-48C is thought to be much more efficient, Norm Princen, Boeing's chief engineer on the project, told CNET, and its engines have been moved forward in such a way that they are shielded, making it even quieter than the B version. "The engines are above aft center," Princen explained, "to make sound bounce up or to the side."
The theory is that pilots will find the X-48 very much like standard transport planes -- but with a 20 percent to 30 percent improvement in fuel efficiency. No one yet knows how the X-48 will be used, but most people believe it could serve in a wide range of roles: a bomber, a tanker, a transport, a command-and-control plane, or even a commercial jetliner. But since it has no windows outside the cockpit, some worry that passengers will be uncomfortable flying in it. Princen told CNET that a full-size X-48 may feature "virtual" windows that could alleviate some such passenger concerns. Still, when the full-size plane begins to fly, the U.S. Air Force will probably be its initial customer.
The X-48 team hopes to fly the C version about 20 times, during which they will gather data and attempt to settle on the size for the next prototype version. But Princen said the C version is likely the last remotely controlled prototype. The next iteration will probably be human-piloted and be fitted with most of the capabilities of the final plane, at least in terms of range and altitude. But it will be at least 4 years before that plane is ready, and 10 years before the final version -- which is expected to feature a 240-foot wingspan and a range of 11,000 nautical miles -- is finished.
The X-48C has a top altitude of 10,000 feet and can fly for 35 minutes. Today, it flew for just 9 minutes and reached a top altitude of 5,500 feet, but NASA said it considered the flight "successful." The space agency and its partners will conduct analysis of the X-48C's performance and may put it in the air again as soon as Thursday.
The X-48 team and several of its competitors, including Northrop Grumman and Airbus, believe that hybrid wing-body planes are the design of the future because they have a great deal of internal volume for cargo and fuel in the interior of the main, "welded" area of the fuselage. As well, the plane has a low profile, which lets air "scrub" over its body more efficiently than today's designs. Princen explained that while Boeing estimates fuel efficiency has increased by up to 50 percent since its 707 jet first began flying in the late 1950s, the standard engine and wing design has probably reached its peak efficiency. "At some point," he said, "you have to make a radical shift in the shape of a plane."
And that means a plane like the X-48, or a similar hybrid wing-body aircraft, could very well be the next universally adopted design. "The question is not if, but when," Princen said, "and who will build it."