WINGING IT; As aircraft designers look to the future, they consider the philosophy of less is more

The days of flying inside a long tube with a tail and wings could soon be a quaint memory.

Engineers are working on a futuristic design for commercial and military aircraft, a hybrid flying wing similar to the B-2 bomber flown by the Air Force.

The experimental concept actually goes much further back than the B-2, mirroring a single-wing airplane from the 1940s - a project canceled in its infancy. But aerospace engineers for decades have dreamed of perfecting what they call the blended-wing body, and their latest creation took to the air in test flights this summer.

"It's basically a tailless aircraft," said Dan Vicroy, an aerospace engineer with Langley Research Center in Hampton, where the vehicle is undergoing extensive testing.

Known as the X-48B, the prototype plane has distinct advantages over other aircraft in weight and efficiency. Its single, blended wing gives it enormous "lift" - the upward force that keeps a plane flying.

"So for the same size as a conventional plane, we save about 30 percent in fuel," Vicroy said.

The world of engineering offers no free rides, though, and the blended-wing body has one big disadvantage: Without a tail, the airplane is unstable. To compensate, the craft must be built with smart materials and be computer-balanced to correct itself in flight. Wind tunnel tests reveal how and where modifications can be molded into the aerodynamic blueprint.

"It's got 20 control surfaces," Vicroy said. "The question is how you blend them to give you the handling qualities you want."

Because of its efficiency - aerodynamic and in fuel savings - a blended-wing body commercial craft could be built to carry a greater number of passengers, as many as 800, experts say. The military likes the flying-wing concept because of its potential to deliver more bombs over longer distances on less fuel, as the B-2 has shown.

The X-48B mimics the B-2, though much of the bomber's technology was devoted to its stealthy ability to hide from radar. The experimental airplane in many ways harks back to the days after World War II, when the military launched its flying-wing program.

An exotic-looking plane known as the YB-49 made its maiden flight 60 years ago, and test flights continued for nearly two years. The jet-powered airplane could carry 10,000 pounds of bombs farther on less fuel than conventional B-35 bombers of the time. It also could stay in the air for nine hours, six hours of which were above 40,000 feet - an impressive feat for its day.

But during a 1948 test run high over California, the plane's wing came apart, killing the crew. Subsequent test pilots confirmed the plane's instability, and the military ended the YB-49 flying-wing program in 1950.

Its legacy didn't die. Industry experts say a blended-wing body military aircraft could be in service within 10 to 15 years and a commercial version at least a decade later.

Kurt Loft is a staff writer for The Tampa Tribune in Florida.