DARPA's Quest for the Ultimate Heavy Lift Seaplane: The Liberty Lifter
Orion Goodman
The Liberty Lifter is designed to carry heavy payloads over long distances.
The Aurora concept depicted above, is the first of two designs in consideration, a single hull, high wing, eight turbo prop proposal by Aurora Flight Sciences.
DARPA
DARPA has chosen two opposing designs for the Liberty Lifter, a full-scale seaborne heavy lift demonstrator with a Wing-in-Ground Effect (WIGE). DARPA launched a project in 2022 to develop an aircraft capable of lifting more than 100 tonnes of payload, with a ferry range of 6,500 nautical miles and the size and capacity of a C-17 Globemaster III transport aircraft.
The "ground effect" or "wing-in-ground effect" phenomenon at the heart of one of the Cold War's biggest mysteries is the key to this performance. In the late 1960s, American spy satellites observing the Soviet Union spotted the Caspian Sea Monster, a massive aircraft flying over the Caspian Sea. This aircraft had stubby wings that couldn't support its weight, causing analysts to be perplexed.
The aircraft was later revealed to be an ekranoplan, a type of ground effect vehicle developed by the Soviet military for carrying a heavy missile load while avoiding radar detection. The key was flying at such a low altitude that the aircraft could benefit from the ground effect. When an aircraft flies close to the ground or water, it creates an air cushion between itself and the ground, reducing drag and increasing lift.
On the other hand, Ground-effect vehicles have limitations, such as not performing well in rough seas. The Liberty Lifter project aims to address these shortcomings and advance technology by developing an aircraft that can transport heavy loads over long distances, operate without maintenance for weeks, take off and land on water, and be built using low-cost boat-building techniques.
The second concept proposed, by General Atomics and Maritime Applied Physics Corp.
DARPA
Aurora Flight Sciences is working on a traditional flying boat design with a single hull, high wing, and eight turboprop engines during Phase 1, while General Atomics and Maritime Applied Physics Corporation are working on a twin-hull, mid-wing design with 12 turboshaft engines for improved water stability. The first phase is expected to last 18 months, with the successful design being manufactured and demonstrated as a full-scale Liberty Lifter X-Plane in 2024.
"We are very excited to begin this program and work with both performer teams," said Christopher Kent, DARPA Liberty Lifter Program Manager. "Through their distinct design approaches, we will be able to explore a significant design space during Phase 1."
