Plane Nation

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

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

The Muppets

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

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.”)

• “Kermit Kruiser”: Low noise. The engines sit atop a twin-fin tail, so that 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 aerodynamic 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 a wide-body seating 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” or “unducted fan” 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 confirmed. At slower speeds, this offers great fuel efficiency.

One internal drawing shows the rotors on the back of the engine, as depicted in The Seattle Times illustration; another shows them on the front, the more usual position.

“That speed is not acceptable in the current marketplace,” Mooney said. “But in the future, if fuel burn becomes an even bigger driver, airlines and passengers may be willing to trade speed for lower fuel costs.”

Back in the 1980s, Boeing flew an experimental prop-fan engine on a 727. That research ended after oil prices fell and removed the incentive to save fuel.

• “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 seems to be 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. One disadvantage is that most passengers are far from a window. Honeydew appears to be an intriguing compromise.

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