'Green' aircraft will look different, use less fuel



Bio | Email


Posted on November 4, 2009 at 7:52 PM

Updated Friday, Jan 29 at 5:56 PM

NASA's X-48 is an example of a "blended wing" aircraft that might be a picture of the future, as aircaft makers strive to save fuel and shrink greenhouse emissions by using cutting-edge technology and exotic form factors.

"As an industry, we realize we have a responsibility to the human race, and we're going to do the best we can," said Airbus spokesperson Renee Martin-Nagle.

To save fuel, designers are rethinking the very basic and familiar design of an airplane. Today's airliners are basically a tube (the fuselage) placed between a lifting body (the wings).

In a "blended wing" aircraft, the fuselage is shortened and flattened, becoming part of the lifting body. The whole aircraft functions as a wing.

This is not a new idea. The military's B-2 stealth bomber is a flying wing.

But it was pre-dated by the Burnelli UB-14, designed by Vincnet Burnelli, a Texan, in the 1930s.

His concept incorporates a boxy cabin into the wing to improve safety and fuel efficiency. Burnelli patented the design, but his heirs say that for political and commercial reasons, the aircraft was barred from production.

Because of its construction, Burnelli's plane was not only more fuel efficient, but safer to fly. In one test flight, the UB-14 went down in a cartwheel crash; the the cabin remained intact.

Now U.S. aircaft manufacturer Boeing sees this concept as a future aircraft.

"I think you'll see a drastic change and shape in the kind of aircraft that are flying," said NASA's Gary Kitmacher.

The aircraft cabin will become a new environment. For structural reasons, the core of the plane will have to be a room-like space, not a narrow tube.

If you're sitting in a "room" the the center of the aircraft, you won't have a window; you'll have a video screen to view your progress.

"There will be cameras that will give you a view outside, but it will not be a window if we go to this new configuration," Kitmacher explained.

Engines will change, too.

Conventional jet engines will be simplified to save weight, and reorganized internally to cut fuel consumption.

They may give way to what's called a rotor engine or unducted fan. This system puts the propulsion blades outside the engine instead of inside, gaining fuel savings through simplicity.

Aircraft manufacturers know they will be an environmental target as a producer of greenhouse gases.

"You have to look at the efficiency of the aircraft — and that's every aspect of the aircraft," Nagle said. "From the materials that go into it, to the design of the airframe, to how the engine functions and combusts the fuel. And then you also have to look at the fuel that the engine is using. So I think it's a total package that we have to consider."

The industry is looking to save up to 25 percent through more efficient aircraft, 15 percent through better engines.

Improvements in air traffic control — including more direct routing and altitude control — mean that passengers just might get to their destinations sooner, even if they can't look out the window.