Boeing concepts go ‘beyond the horizon’
June 7, 2006

SEATTLE — When Boeing names an airplane design after a Muppet, it must be different.

Two teams at the company are re-imagining the airplane in futuristic configurations that sprout wings, tails and engines in unexpected shapes and places.

The research aims in two directions: low-cost airplanes, and environmental-friendly planes that will be quieter, use less fuel and leave fewer pollutants.

In the latter category is the “Kermit Kruiser,” a low-noise concept airplane with main wings radically swept forward rather than back, and miniature wings on the front.

Then there’s the “Fozzie.” It has a “Pi-tail” — two vertical tails joined by a piece across the top, and sips fuel because it flies slower using open-rotor jet engines that resemble propellers.

The concepts are “intended to help us focus technology on a future out beyond the horizon,” said Dan Mooney, Boeing vice president of product development, who directs both research teams.

The documents show Boeing has looked at other concepts as well: a supersonic business jet; a megasize freighter; airplanes that use biofuels or hydrogen; and even a “reduced crew” airliner — one with no windows in the cockpit, judging by a sketch in the Boeing documents.

But of all the potential concepts, Boeing has prioritized the “low-cost” and the “green” planes for further research this year. Both teams have begun work with engine companies on the various propulsion alternatives.

The Boeing documents include assessments of similar projects that rival Airbus has mentioned at scientific conferences.

In an interview, Mooney declined to discuss proprietary details of the designs but explained what researchers are up to.

He said the latest airplanes being sold today, such as the 787, are designed to meet airlines’ projected requirements for the next two decades. Designers balance cost, fuel efficiency, capacity, range and other factors.

The low-cost team is studying the benefits of options such as long, thin wings and new engine types. That team has not yet envisioned new structural designs.

In contrast, the Green Team, with a broad mandate to address diverse issues of fuel burn, noise and emissions, has considered some widely differing airplane structures — each with its own whimsical code name. (The Muppet theme may be a reference to the song Kermit sang on “Sesame Street”: “It’s not easy bein’ green.”) The models include:

• “Kermit Kruiser”: Low noise. The engines sit atop a twin-fin tail so the noise is reflected upward. The wings are placed so far back they join the fuselage right at the horizontal stabilizer. And most radically, the wings sweep forward, not back, lowering drag and increasing maneuverability at the price of some stability. Keeping this tail-heavy aircraft stable in flight requires a canard — those mini-wings up front. The plane would be seat nine abreast.

• “Fozzie”: Ultra-low fuel burn. The airplane is designed to cruise at a much reduced speed — 500 mph rather than the typical 600-plus mph of current jets. That would add an hour to the typical transcontinental flight.

Attached to a tail with twin vertical fins and a crossbar (called a Pi-tail because it resembles the Greek letter pi) are engines with an “open rotor” design.

The plane has a fanjet gas-turbine engine of the sort used on airliners today, but without the usual duct encasing the fan, Mooney said. At slower speeds, this offers great fuel efficiency.

• “Beaker”: Low emissions. This airplane has the low fuel burn and same low cruise speed of Fozzie. It has low-emission engines and long, very narrow wings perpendicular to the fuselage. The wingspan is such that the wings must fold to fit an airport gate.

• “Honeydew”: Low fuel burn. Another wide-body, this aircraft is a meld of the traditional “tube-and-wing” shaped airliner and the often-touted “Flying Wing” design that produced the B-2 bomber.

The resulting delta-shaped wing blends in a graceful curve into the fuselage. Yet there is still a distinct fuselage at the front.

The Flying Wing design is more aerodynamically efficient, but most passengers are far from a window. Honeydew appears to be an intriguing compromise.

So how realistic are these cool-looking airplanes?

“When you look at where energy costs are going in the next decade, it could be time for a change in the rules,” said Jerry Ennis, a retired vice president at Boeing’s Phantom Works who worked on prototypes.