The Pelican, seen here in a computer illustration, is designed to fly at an altitude of 20 feet, and would be the largest plane ever built if it goes into production.
By Mark Cherrington
If you want to really test your imagination, try to picture the airplane that Blaine Rawdon ’73 is designing. Start with the biggest Boeing 747 sitting on a runway. That plane is, of course, huge, almost ludicrous in its enormousness. Now imagine it twice as long, double the wingspan, and make it seven times heavier. Now you’ve got the measure of the Pelican—the largest airplane in the world. Next to Rawdon’s plane, the 747 would look like a Cessna. If you stood the Pelican on one wingtip, the other wingtip would almost reach the top of a 50-story building. Of course, tipping the plane on a wingtip could be difficult, because the Pelican weighs 6 million pounds. It has 76 steerable tires to distribute that weight and keep it from turning runways into rubble. It is powered by eight 80,000-horsepower turbine engines—like those in a cruise ship—driving four counter-rotating propellers, each of which is as tall as a five-story building. Although it is not intended as a passenger airliner (for numerous practical reasons), the Pelican has a payload equivalent to 8,000 passengers, their bags and cabin furnishings. Perhaps most remarkable, this behemoth has a cruising altitude of 20 feet.
Blaine Rawdon '73
At the moment, the Pelican doesn’t exist, except on paper. Rawdon is a
designer at Phantom Works, the research and development arm of Boeing. The purpose
of Phantom Works is to explore the outer limits of what’s possible in airplane
design, the what-ifs of aviation. To come up with a final, real airplane, designers
like Rawdon may explore 100 variations; a whole design track may fail because
of insurmountable technical issues, prohibitive cost or ultimate lack of customer
demand. “The way you work it in an advance design project,” Rawdon
says, “especially on the technical side, is that you conceive of the thing
and then you draw it up and then you try to figure out the areas where you’re
going to have trouble, where there are risks. You make a list of those risks,
and in the next cycle you try to understand whether they’re solvable and
what the implications of the solutions are. And if there are any that are show-stoppers.
Show-stoppers are our biggest concern, because you’ve got to find a way
to solve that problem. We’re at a stage now where we’re trying to
resolve some of our concerns.” It may take 10 years for the Pelican to
become a real plane—if it becomes a real plane at all—but Rawdon
is optimistic about its future.
The Pelican started with a Department of Defense request to come up with a craft that could lift a million pounds of cargo and carry it to a distant battlefield. (The Pelican can in fact carry nearly 3 million pounds.) This is part of the military’s new emphasis on mobility, its desire to be able to deploy an entire division—10,000 to 18,000 people and all their related weapons systems, vehicles and support materials—to any location on earth within 120 hours, a goal that is not possible to achieve with existing ships and planes.
“We actually started out with airships—blimps and dirigibles,” Rawdon says. “They provide lift without any power, so they’re very good at holding things up. But when you try to move things with them at any speed, it starts to take a lot of power because there’s so much surface area: there’s a lot of friction.”
To get around that problem, Rawdon decided to make his airship wider, to create dynamic lift, which also let him make the ship smaller, to reduce the friction. “So then it was sort of half blimp and half airplane,” he says. That solution, however, proved to be inefficient, so he went back to a full airship, but added gigantic wings. “That was better,” he says, “but we realized the wings were providing two-thirds of the lift and the buoyancy was only one-third of the lift, and that’s sort of stupid because now you’re carrying around this great big blimp making all this drag, so why not get rid of the blimp and just use the wing, which means you’re all the way to the airplane.”
The blimp-with-wings, however, did have two interesting qualities. First, its wings were enormous, some 700 feet from tip to tip. Second, it flew close to ground. Rawdon realized that if the designers could develop a standard airplane design that maintained these two key characteristics, they could take advantage of an aerodynamic phenomenon called the ground effect, which maximizes efficiency by coupling a plane’s wings to the earth, thus reducing the energy normally transferred to the air in the process of making lift. (Rawdon likens the phenomenon to the greater efficiency of walking on pavement rather than sand.)
The ground effect occurs when airplanes (or birds like pelicans) fly close to a land or water surface. The primary effect is reduced drag, with the degree of reduction depending on the plane’s wingspan and height above the surface. To maximize the ground effect, the Pelican has a 500-foot wingspan and is designed to fly as close possible to the ground, generally at a cruising altitude of 20 feet. For the most part, Rawdon says, the Pelican would fly over the ocean, using sophisticated computer control and scanning technology to avoid rogue waves, ships, islands and other obstacles. The plane could also fly at altitudes of up to 20,000 feet (although with somewhat less efficiency) when flying over land or preparing for airport landings.
Computer illustration: Boeing; Photo: Frank Ward