A concept aircraft currently under development at Boeing’s Phantom Works Research and Development unit might be the largest airplane to ever fly, but it won’t set any altitude records. Its called the Pelican and it would have a normal cruising altitude of only twenty feet because it uses the concept of ground effect to achieve lift.
Performance specifications say this ground effect vehicle (GEV) will have a wingspan of 150 meters and be able to carry up to 1,400 tons of cargo. By comparison the current giant of the skies, the Russian An-225, has an 88.4-meter wingspan and can lift 250 tons.
Because the plane skims the surface during flight, it is only practical over large, smooth bodies of water. Flying close to the water, the wing’s downwash angle and tip vortices are suppressed, resulting in a greatly reduced drag which leads to outstanding cruise efficiency. This would translate into a range of 10,000 nautical miles in trans-oceanic flight. Operating from paved runways, the plane has thirty-eight fuselage-mounted landing gears with seventy-six tires to distribute the weight.
The Pelican is designed to be a hybrid GEV, allowing it to also fly at higher altitudes up to 20,000 feet. But the range would be greatly reduced to 6,500 nautical miles when not using the ground effect.
While the Pelican is yet to become a prototype the concept is hardly a new one. For decades the Russians have experimented with aircraft they called WIG (Wing In Ground-effect) planes. A WIG craft, like the Pelican, sits on a cushion of air created by aerodynamics rather than by an engine.
This means that it can only fly when the WIG craft has sufficient forward speed. This is called a dynamic air cushion as opposed to the hovercraft's static air cushion.
The Soviets had great plans for these planes. Just like Boeing’s Pelican they discovered the high efficiency of ground-effect craft. The only difference from the Russian WIGs and the Pelican is that the Soviet craft did not have the ability to fly higher than 20 feet. They would be restricted to use over large bodies of water.
Two WIG planes are especially interesting. The Orlyonok A90 is a large WIG prototype with one huge turboprop mounted high at the tail fin for cruise thrust and two turbofans for takeoff, acceleration, and landing. Two hydro skis are mounted at the underside of the fuselage, one in the front, and another at the center of gravity.
Designed in 1974, the original plans were to build 120 Orlyonoks as troop transport and assault vehicles, but only four were built-- one of which has been used for static tests only. But the WIG craft had a troubled service history; the first Orlyonok crashed during a VIP demo flight in 1975. In October 1979 the Orlyonok entered service in the Soviet Navy, where one was lost in a crash in 1992. Unfortunately the crew didn't survive the accident. The last flight of the Orlyonok took place in October 1993, and currently the remains of the last Orlyonoks are rusting and falling apart at their base.
There have been plans to modify one of the surviving Orlyonoks as a transport, carrying up to 150 passengers in a single deck layout or up to 350 passengers in a twin deck layout. A cargo version of the craft was planned to have a payload of thirty tons.
The Soviets also started a WIG warship program called the Lun in 1970, but assembly of the first Lun did not start until 1983. In July 1986 it was launched into the Volga River. During Spring 1987 sea trials commenced on the Caspian Sea.
The first Lun was designed and built as a missile launching strike craft primarily for anti-submarine tasks. It carried 6 missile tubes for this mission, and had a top speed of 500 kilometers per hour. The second Lun was under construction during the collapse of the Soviet Union and the project was abandoned. In 1997 Russian television showed the Lun half sunk in the water at Kaspiisk Naval Air Base.
The Russians built a whole range of WIG aircraft ranging from eight-engine monsters to small pleasure craft. Today in the United States and Europe there are several homemade ground-effect planes usually seating no more than four passengers.
If Boeing's enormous Pelican ever flies, it won't be until the end of the decade at the soonest.