DOD Abandons Cargo Seaplane Program

Aurora Flight Sciences tweaked its original Liberty Lifter design to move floats to its wingtips and adjust its tail to better accommodate its aft cargo door. (Aurora Flight Sciences)

The Defense Advanced Research Program Agency (DARPA) developed an inexpensive, long range, C-17 sized cargo seaplane, tentatively called the "Liberty Lifter" which could land even in rough seas and would allow airlifts to many places that large, long range cargo planes could otherwise not go, filling an important gap in U.S. military capabilities. But, despite the project's success, the program has been abandoned:

The nearly three-year-old Liberty Lifter program was intended to design and build — and possibly float and fly — a long-range, low-cost seaplane that could take off and land in rough seas. DARPA said in 2023 that it wanted the plane to have roughly the same size and capacity as a C-17 Globemaster, which can carry more than 170,000 pounds of cargo such as M1 Abrams tanks.

In a statement to Defense News, DARPA confirmed it had concluded the Liberty Lifter program in June. Aviation Week first reported the ending of the Liberty Lifter program.

“We’ve learned we can build a flying boat capable of takeoff and landing in high sea states,” program manager Christopher Kent said. “The physics make sense. And we’ve learned we can do so with maritime building techniques and maritime composites.” But DARPA said it will not move forward with building an aircraft, which would only be a demonstrator.

“We think our findings validate the hypothesis we had going in: you can build platforms that fly significantly cheaper and at significantly more locations than we do today,” Kent said. “This opens up a pathway for next generation aircraft to be built using far more efficient construction technologies.” DARPA also said more work needs to be done to blend maritime construction with aircraft certification. . . . 

“Through the Liberty Lifter program, we were able to show the viability of the design and the feasibility of novel manufacturing techniques,” Aurora said. . . . 

DARPA hoped creating a cargo seaplane could lead to new opportunities for the military and commercial organizations to conduct fast logistics missions, as well as develop innovative manufacturing techniques and materials to bring down the cost of building large aircraft. . . . . Aurora and DARPA used simulations and tests of scaled models to demonstrate the seaplane’s technical design, as well as building and stress-testing examples of the new methods and materials intended for the plane. . . . DARPA confirmed it spent about $98 million in all on Liberty Lifter.