Boeing looks to the future with sweeping designs to change the commercial airline picture
By Bryan Corliss
Herald Writer
Boeing’s Sonic Cruiser is getting all the headlines, but design work continues on another futuristic plane, the Blended Wing Body, the program’s leader told fellow engineers during the recent world Aviation Congress in Seattle.
Boeing is working with NASA on a 35-foot model of the plane it hopes to have flying by 2004, said Robert Liebeck, who heads the research project at Boeing’s Phantom Works in Long Beach, Calif.
A European design team from Cranfield University in England also is working on a similar design and hopes to fly its own 16-foot model ready by next summer.
Both groups see great potential for the blended wing, a takeoff on older flying wing designs, which shows promise as a fuel-efficient, environmentally friendly alternative to the conventional jetliner.
"We think it’s doable," said John Fielding, head of the Air Vehicle Technology Group at Cranfield’s College of Aeronautics. "But there are some issues."
For most of the history of powered flight, airplanes have been designed as flying tubes, cigar-shaped bodies carried aloft on wings.
But for most of that time, aircraft designers have also flirted with the idea of a flying wing.
British aircraft designer John Dunne flew a biplane version of a flying wing in 1912, according to information from Cranfield. German designers experimented with both propeller- and jet-powered flying wings during World War II, and British and American designers both built jet-powered flying wing prototypes in the years after.
The U.S. Air Force now flies B-2 bombers that are essentially flying wings. But the flying pipe has remained the standard.
The Blended Wing Body, or BWB in aviation parlance, is not a true flying wing; it’s more like a flying saucer with wings attached.
Boeing’s involvement with the design goes back to 1992, before the McDonnell-Douglas merger, Liebeck said. McDonnell-Douglas engineers "wanted to look at a different way to design a jetliner," Liebeck said. "The cigar’s an option we’re all familiar with — what about a saucer?"
The saucer-shaped body does generate lift, Liebeck and Fielding said. That’s an advantage over cigar-shaped bodies, which are essentially dead weight that must be hauled through the sky.
That’s a significant advantage, the designers said. Because they’re more aerodynamically efficient, BWBs would be more fuel-efficient.
Combine the benefits of the blended wing design with lightweight composite materials, and wind-tunnel tests show you could have a 550-passenger jet that burns 32 percent less fuel than the similarly sized Airbus A380, Liebeck said.
More fuel efficiency means less pollution, Fielding added. That’s a big consideration in Europe, he said, where the generation of greenhouse gases by high-flying airplanes is becoming a political issue.
Blended wing bodies also would be quieter, because they wouldn’t require engines as powerful as those now used. And both Boeing and Cranfield are looking at designs that mount the engines atop the planes, rather than under the wings, so the plane’s body would deflect some of the engine noise.
Simple geometry also means the wedge-shaped body would have more interior room than a tube-shaped plane of similar length. (Think of a slice of pie, compared to a candy bar.)
Early Boeing/NASA designs showed a plane capable of carrying 800 passengers that wouldn’t be much larger than a current Boeing 747-400, yet could still carry enough fuel to fly as far as a 747 does — 7,000 miles.
The working design is for a 480-seat jet that flies 9,000 miles, Liebeck said.
The interiors would be more comfortable than flying tubes, he said, adding, "I walked into a mock-up and it felt more like a railroad car than an airplane."
And Liebeck sees huge savings in production costs once the basic configuration is set.
He sees the potential for a family of blended wing jets, carrying from 250 to 450 passengers. Each would have the same nose section and wings, no matter what the size of the plane. The only difference between the 250-passenger model and the 450-passenger model would be the size of the passenger compartments in the center saucer section.
Those could be expanded using modular sections, Liebeck said. They could be put together almost like Legos — snap in big center modules for large passenger loads, take them out for planes carrying smaller loads.
All that adds up to a great degree of commonality, which would drive down the cost of building the planes, he said. "Once you’ve designed one of these, you’ve designed them all."
But there are hurdles to be overcome, the designers said.
One of them is the way passengers would feel about interiors. There wouldn’t be any window seats. Boeing is testing putting video screens showing the sky outside the plane on the back of each seat, Liebeck said. It’s also considering the idea of "virtual skylights" — video displays of the sky built into walls and ceilings.
So far, focus groups seem to think those ideas would be fine, Liebeck said.
"They didn’t find any show stoppers," he said. "It will be different. We need to do more work there."
Fielding said emergency evacuation is another potential problem — how to design enough doors to get everyone out of the plane quickly. It’s one that’s solvable, he said, "but more research needs to be done on that."
And going away from the cylindrical tube means new pressures on the plane’s interior and exterior surfaces and structures, Liebeck said. "Fatigue is an issue."
But none of the challenges appears insurmountable, both Liebeck and Fielding said.
The blended wing could be the next milestone plane in aviation history, like the DC-3, 707 and 747, Liebeck said — the kind of jet that gives Boeing its edge back.
The high-speed Sonic Cruiser is getting more priority right now, he acknowledged. The hope is to have it flying around 2008, Boeing officials say. The BWB isn’t likely to be in commercial service until about 2015, according to information from NASA.
But Liebeck figures that with both planes on the drawing board, "we’ve got Airbus surrounded."
"We’ve got a green airplane," he said. "We’ve got a fast airplane. They don’t have either one."
You can call Herald Writer Bryan Corliss at 425-339-3454
or send e-mail to corliss@heraldnet.com.
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