Image: Northrop Grumman
Northrop Grumman reached deep into its history, as well as its recent past, to draw inspiration for an airliner of the future — a flying wing much like the B-2 stealth bomber.
The firm designed the concept for NASA’s Environmentally Responsible Aviation program, an effort to develop an airplane that is quieter and more fuel efficient than today’s airliners. Although the program has drawn interest from several aviation firms, only Northrop Grumman is reaching back to the future. The company has been building flying wings since the 1940s, and anyone with even a passing knowledge of aviation can see the concept’s resemblance to Northrop Grumman’s B-2 bomber.
Studies like the Environmentally Responsible Aviation program always draw wild ideas, ranging from blended wing bodies to double-wide fuselage designs. Such things are nothing new for Northrop Grumman.
Jack Northrop first started flight testing flying wing designs in the 1940s. The company has developed several variations on the theme have flown, including propeller- and jet-powered examples. The company also has considered flying wings as massive airliners. But stability problems promoted the company to shelve the idea for decades. Only when computer controlled fly-by-wire technology was available did the design become viable as a practical platform for large aircraft.
Northrop Grumman’s flying wing airliner concept has a wingspan of 230 feet, 58 feet wider than the B-2 bomber, according to Aviation Week & Space Technology. The cargo version (top photo) would have a wingspan of 260 feet, though the cabin area would be smaller than the passenger version, according to the article.
The shielded engines greatly reduce the noise signature, and they’re often seen on flying wing ideas. The sleek design also could improve fuel efficiency, though existing flying wing designs have yet to fully realize that potential because of drag penalties that occur through the control of the aircraft.
An artist's rendition of a Northrop Grumman flying wing with the rear loading door open. Image: Northrop Grumman
A flying wing can significantly reduce drag in part because the sleek design does not have protruding surfaces like a tail to disrupt the flow of air. Without a horizontal tail, the aircraft does not have the added induced drag generated when the tail generates lift, which in the case of conventional aircraft is actually pushing down rather than lifting up.
The tail of most airplanes actually creates a lift force downward to balance the weight of the aircraft and the lift of the main wing. This force is counterproductive to the main wing, which is generating lift to keep the entire airplane aloft.
Aircraft equipped with canard wings, like many of the designs from Burt Rutan also reduce the drag due to the lack of a conventional tail surface pushing downward during flight.
But because a flying wing does not have a vertical tail surface or winglets, the aircraft tend to have yaw instability. This means it is more likely to rotate in the horizontal plane with the wing tips effectively shuffling forward and back. To control this, and to control the airplane in a turn, drag-producing control surfaces along the wings are used during flight. These constant small corrections eliminates some of the inherent yaw stability of a conventional design that flies through the air more like an arrow with feathers guiding it straight (and no fly-by-wire computer having to keep it on path to the bullseye).
These stability issues led to Northrop abandoning the flying wing designs of the 1940s. But with modern fly-by-wire systems, many of the issues can be reduced or eliminated. And in the years to come there may even be ways to fully utilize the aerodynamic benefits of what is an efficient design.
Of course there is still the problem of passenger windows and where to put those slides and emergency exit rows to get everybody out of the airplane in a timely manner. But those problems should be relatively easy to solve.
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