Tech Briefs

The main commercial application is transoceanic cargo transport.

There are two commonly used options to transport large-volume and heavy cargo across the ocean: container ships and airline transport aircraft. Container ships take about 3 to 4 weeks to deliver goods, and airline transport aircraft take about 2 days. This innovation is a flying boat aircraft designed for heavy lift cargo utilizing wing in ground (WIG) effect. The wing in ground effect has many names, but it refers to the phenomenon where an aircraft flying close to the ground has increased lift and decreased induced drag. The induced drag of the aircraft is half of the induced drag compared to flying at altitude when the aircraft operates within 10% of its wingspan to the surface. The lift is double compared to flying at altitude when the aircraft is operating within 10% of its chord length to the surface.

Heavy Lift WIG cargo flying boat pulling up to the pier.

Previous designs had limitations. The Boeing Pelican, a large cargo aircraft intended for transoceanic cargo missions, was designed to take off and land on inland runways. It required significant compromises to the design to operate in existing airport infrastructures, and then only at the very largest airports. In addition, the mass of the aircraft required 76 wheels to distribute its weight. Another design, the Korabl Maket (KM) Ekranoplan (a.k.a. Russian Caspian Sea Monster), was a large, low-flying aircraft designed in Russia. One prototype was built for testing. The Russian Ekranoplans were not large enough to get a good operating cost per pound of payload, and were intended to meet military needs where operating costs were less of a factor.

The Heavy Lift WIG Cargo Flying Boat is designed to provide heavy lift cargo transport capability over large water distances. It will fill the gap between the current paradigm of 3- to 4-week heavy cargo delivery with container ships, and 2-day cargo delivery with transonic airline transport aircraft with approximately 1-week heavy cargo delivery at a cost that is significantly less than large transport aircraft. The Heavy Lift WIG Cargo Flying Boat utilizes existing port infrastructure for loading and unloading for easy and immediate integration into the current cargo transport system. This initial design is capable of carrying 32 standard 40-foot-long shipping containers at 1.8-million-pound capacity.

The flying boat will open the leading edge blowers on takeoff.

The flying boat has a large open section on the top of the wing to allow for easy loading of shipping containers. It utilizes the existing container's ship port and pier-side infrastructure. The wing-span and length of the flying board are similar to the length and beam of current container ships. The containers are loaded into the docked flying boat secured to the pier with the existing cranes. There is no upper hatch over the top of the containers. There are three standard container heights, and legs are placed under the short containers to get the tops at equal heights. Once fully loaded, the flying boat will get underway and taxi out to the ocean for takeoff. Distributed electric fans on the top aft of the wing are the primary source of propulsion. In addition, on takeoff, the flying boat will open the leading edge blowers, dropping the exit cover down on the bottom of the leading edge. Once airborne and fully clear of the water, the leading edge fans will be turned off and the duct covers will close. The flying boat will fly at about 20 feet above the wave tops to fly WIG effect. It should be noted that 99% of the ocean has wave heights of less than 13 feet. The aircraft's speed easily enables it to out-maneuver storms, and therefore can avoid operating in conditions with waves greater than 13 feet. If desired, the aircraft could be flown at higher altitudes, but at the expense of greater power required to fly. The flying boat has a traditional flying boat landing.

The leading edge lift blowers provide additional lift at takeoff by forcing more air under the wing, creating a pocket of high-pressure air much like a hovercraft with its pressurized air skirt. The flexible lower doors for the blowers create a chamber constrained by the fuselages on the sides, wing flap on the back, and leading edge blower doors on the front, which provides a massive lift increase to assist the aircraft in breaking free of the water.

The distributed fans on the top rear of the wing provide two benefits. First, the location of the fans on the top of the wing increases the circulation around the airfoil, thus generating significantly more lift than an airfoil in isolation. Second, the fans are energizing the boundary layer air, which theoretically provides greater propulsive efficiency.

This work was done by Douglas Wells and William Fredericks of Langley Research Center. NASA is seeking partners to further develop this technology through joint cooperative research and development. For more information about this technology and to explore opportunities, please contact This email address is being protected from spambots. You need JavaScript enabled to view it. . LAR-18790-1

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