Down the Line: Big Bird for Big Loads
It’s a bird, it’s plane. No, it’s a flying container ship. If a group of Boeing engineers have their way, a revolutionary aircraft will feature attributes of all three. The Pelican is a high-capacity cargo plane concept currently being studied by the Boeing Phantom Works (Seal Beach, CA).
The four-engined ultra-large transport would stretch more than the length of a football field and have a wingspan of 500 feet--that’s 2.5 Arial the wing width of a Boeing 777--with a payload capacity of 1,400 cargo tons. Although initial sketches of the proposed aircraft look similar to Howard Hughes’ infamous Spruce Goose, the Pelican is not a seaplane. The aircraft would land and take off from conventional airport runways with the assistance of 38 double-wheeled landing gear to support the enormous weight.
To provide enough clearance on the ground, the outer half of each outer wing panel is designed to fold up. The angle of fold may vary from a minimal amount for takeoff and landing to up to 90 degrees for ground operations. Once airborne, the wing tips would fold down to their in-flight position and fold up again for landing.
Designed primarily for long-range, transoceanic transport, the Pelican would fly as low as 20 feet above the sea, taking advantage of an aerodynamic phenomenon that reduces drag and fuel burn. Over land, the aircraft would fly at altitudes of 20,000 feet or higher.
"The Pelican can broaden the range of missions for which airplanes are the favored way to deliver cargo," says Blaine Rawdon, program manager. "It is much faster than ships at a fraction of the operational cost of current airplanes. This will be attractive to commercial and military operators who desire speed, worldwide range and high throughput. We envision that the Pelican can multiply aircraft’s 1 percent share in a commercial market now dominated by container ships."
According to Rawdon, the aircraft’s size and efficiency would allow it to carry types of cargo equivalent to those carried by container ships, at more than 10 Arial the speed. By flying low, the Pelican, like its namesake bird, would exploit the aerodynamic benefits of a phenomenon called ground effect, Rawdon points out. "Flying close to water, the wing downwash angle and tip vortices are suppressed, resulting in a major drag reduction and outstanding cruise efficiency," claims Rawdon.
Riding on top of a cushion of air, the Pelican would experience 70 percent less drag than a normal plane, allowing it to travel further while using the same amount of fuel. The wing-in-ground effect occurs at an altitude equivalent to 10 percent to 25 percent of the wing’s width at the point where it joins the fuselage. The phenomenon increases the ratio of lift to drag for a wing.
"It’s an effect that provides extraordinary range and efficiency," says John Skorupa, senior manager of strategic development for Boeing Advanced Airlift and Tankers. "With a payload of 1.5 million pounds, the Pelican could fly 10,000 nautical miles over water and 6,500 nautical miles over land.
"Flying in ground effect demands the latest flight control technology," adds Skorupa. "Reliable systems will provide precise, automatic altitude control and collision avoidance. Cruise altitude will be adjusted according to sea state, and if the seas get too rough, the Pelican can easily climb to high altitude to continue flight."
In addition to commercial applications, the Pelican also appeals to Pentagon officials. "The Pelican currently stands as the only identified means by which the U.S. Army can achieve its goals of deploying one division in 5 days, or five divisions in 30 days, anywhere in the world," claims Skorupa.