Mad Scientists at DARPA Are Moving Forward With a ‘Flying Sea Monster’ Craft

Photo credit: DARPA
Photo credit: DARPA
  • The Department of Defense’s mad scientist division is looking to develop a plane that can also harness the “wing-in-ground” effect.

  • Nicknamed “Liberty Lifter,” the aircraft would skim the surface of the ocean for tremendous distances.

  • The goal is an aircraft that can deliver heavy transport cargoes to remote islands and naval bases.


Last week, the Defense Advanced Research Projects Agency (DARPA) announced a new project, one that should be familiar to aircraft—and ship—geeks. The Liberty Lifter seaplane transport will harness the “wing-in-ground effect” (WIG) that Soviet-era aircraft, including the infamous “Caspian Sea Monster,” utilized to carry cargo thousands of miles, across distances such as the Indian and Pacific oceans. Although the technology has been tried and abandoned, DARPA seems to think it deserves a second look.

Liberty Lifter “will combine fast and flexible strategic lift of very large, heavy loads with the ability to take off/land in water,” DARPA says in a May 18 press release. “Its structure will enable both highly controlled flight close to turbulent water surfaces and sustained flight at mid-altitudes,” the statement continues. The agency points out that traditional sealift using cargo ships is very efficient, but slow and reliant on the use of ports. Airlift is fast, but relies on airfields that in wartime would need to be captured first.

Liberty Lifter will utilize the WIG effect to travel, creating a craft that can carry transport ship-sized loads, flying much faster than a ship all while being able to take off and land from the water. WIG refers to the phenomenon where lift increases as a craft flies closer to the surface of Earth, while drag decreases; the zone is generally about as wide as the airplane’s wings. A craft operating in this very narrow zone is considerably more fuel efficient, using the same amount of fuel as a regular aircraft.

WIG craft are technically aircraft, using wings to generate lift, and travel at low aircraft speeds (350 miles an hour), but have boat-shaped hulls to take off and land in water. The aircraft look a little like conventional seaplanes, but traditionally cannot fly outside the WIG zone.

The Soviet Union developed several types of WIG craft during the Cold War, including the famous “Caspian Sea Monster.” Soviet WIG craft included variants that carried anti-ship missiles and others that could carry Soviet marines. One of the most famous examples was the Lun, colloquially known as the “Flying Sea Monster.” It was 240 feet long, 63 feet tall, and had a wingspan of 144 feet. It could carry 100 tons of troops and equipment at a top speed of 342 miles per hour to a range of up to 1,080 miles. It was also heavily armed, with six P-270 Moskit anti-ship missiles and four 23-millimeter automatic cannons. The largest Soviet WIG craft, the KM, was 301 feet long and had a top speed of 279 miles per hour.

WIGs had a couple of problems, though. One, they were limited to flying/sailing in relatively good weather and calm seas, as a tall wave could rise up to swat the aircraft in midair. Another problem was that the craft, like all aircraft, turned by banking, which raises one wing and lowers the opposite … potentially into the ocean. The problem was exacerbated by the fact that if a WIG tried to gain altitude to allow one wing to clear the surface, the craft would travel outside the ground-effect zone and lose altitude. As a result, WIG aircraft must turn very slowly—and carefully.

Mastery of ground-effect flight is so tricky that no country has conducted research and development on WIG craft since the end of the Cold War. Russia has shown off concepts and models for WIGs, but the actual crafts are vaporware. In 2002, Boeing announced it was studying a new concept aircraft, the Pelican, which could carry 1,400 tons of cargo up to 10,000 miles over water. Nothing came of that, either.

DARPA seems to have two solutions to the hazards of WIG flight. One is that the aircraft will be stout enough to take hits from the waves, using “innovative design solutions to absorb wave forces.” Second, if a Liberty Lifter encounters turbulent waters, it could simply fly over them: unlike other WIG craft, Liberty Lifter will be able to fly to a maximum of 10,000 feet.

A Liberty Lifter could simply approach a beach, lower a ramp, and disgorge armored vehicles and anti-ship missiles directly on the shore. Liberty Lifter would be particularly useful against China’s militarized islands in the South China Sea, which the U.S. Marines have focused on like a laser in the event of a war. If DARPA can pull it off, a new generation of wing-in-ground effect could rewrite the rules on wartime logistics.

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