Darpa puts two of its partners in competition to develop the design of the Liberty Plan. This giant cargo seaplane will use the ground effect on the sea to transport heavy loads quickly over long distances.
At the end of May, Darpa announced that it planned to design a tactical cargo plane using the ground effect on the sea to cover very long distances at high vitessevitesse. Today, the agency responsible for the development of new technologies for military use is starting its program in practice.
The Liberty Lifter is reminiscent of the ekranoplans, gigantic cargo planes based on this principle, developed by the Soviets and used until the end of the 1990s. For the moment, the Darpa is only at the plank stage. drawing, that is to say what she calls the phase 1.
For this, the agency has just mandated two teams, General Atomics in collaboration with Maritime Applied Physics Corporation and AuroraAurora Flight Sciences in partnership with Gibbs & Cox and ReconCraft. The two groups are developing two concepts of demonstratordemonstrator in large scale. The main idea is to create a seaplaneseaplane cargo ship with the same payload capacity as a C-17 Globemaster III and of approximately the same dimensions.
Two different concepts
The Liberty Lifter must be able to withstand a take-off and a landing on a sea whose Beaufort scale would be level 4, that is to say a so-called light breeze, with waveswaves with a maximum height of 1.5 meters and a ventvent 20 to 30 km/h. The device will then have to be able to evolve thanks to the ground effect above the water on a sea level 5 on the same scale (up to 40 km/h of wind, with waves of 2.5 m max).
Another feature, the Liberty Lifter will be able to rise to achieve a flight at about 3,000 meters above sea level. In any case, Darpa would like this aéronefaéronef stay cheap. For the moment, the General Atomics team is working on a double-hull design to optimize stability on the water and seakeeping. The aircraft is powered by twelve turboshaft engines.
On the side of Aurora Flight Sciences, the device looks more like a flying boat, with a single hull, a high wing with downward-pointing dihedrals and eight turboprops for main propulsion. This phase 1 should last 18 months. Three additional months are planned to plan the first tests. Phase 2 is expected to start in mid-2024, with the constructionconstruction of a full-scale X-Plane Liberty Lifter.
Liberty Lifter, Darpa’s cargo plane that surfs the sea
Darpa is working on a tactical cargo plane using the ground effect on the sea to cover very long distances at high speed. An aircraft reminiscent of the famous ekranoplans used by the Soviets and then the Russians until the end of the 1990s.
Article by Sylvain Biget, published on May 28, 2022
Here is the return of the ekranoplans, the Soviet devices resembling a gigantic seaplane which used the ground effect to fly at low height above water or a flat surface. But this time it’s on the side of the Darpa that this concept wants to see the light of day. The project porteporte the name of Liberty Lifter and it is a tactical cargo plane with a wide range. Designed like a seaplane, the aircraft must be able to take off and land on water and carry very heavy loads. It will also have to remain stable, even on rough waters and also leave the ground effect to be able to fly at medium altitude. Like the Soviet ekranoplans, the Liberty Lifter could fly over the water like a hydrofoil, at very high speeds but, unlike them, it should be more maneuverable and able to fly over rough seas.
The Liberty Lifter should be economical to build, have a long range and be able to carry heavy cargo. On this video, we can see that Darpa has imagined a double fuselage. © Darpa
Un ekranoplan « low cost »
For the moment, Darpa is only in the first phase of this project, that is to say the concept. We can also see it in a video published by the organization (see above). As this aircraft will be able to carry heavy loads, this means that its lift will have to be very important at low speed to ensure a smooth landing without breakage. It will also have to be able to absorb the forces of the waves. Another constraint, it will have to be able to remain operational at sea for weeks without requiring maintenance. Finally, Darpa wants to reduce its production bill as much as possible by using more affordable materials than those used in aviation.
