Huge Ekranoplan-Like Airlifter Design Teams Selected By DARPA

Aurora Flight Sciences and General Atomics have been chosen to compete to design and possibly build the gigantic Liberty Lifter X-plane.

byOliver Parken, Tyler Rogoway|
General Atomics Liberty Lifter
General Atomics


The Pentagon has selected two teams to further develop their designs for a full-scale demonstrator of the Liberty Lifter X-plane. Aurora Flight Sciences (working with Gibbs & Cox, a Leidos company, and ReconCraft) and General Atomics (working with Maritime Applied Physics Corporation) are pursuing two very different designs for phase 1 of the project, as a Defense Advanced Research Projects Agency (DARPA) press release distributed on February 1 shows.

You can read more about the launch of the Liberty Lifter project in this previous War Zone feature from May 2022.

The Liberty Lifter X-plane project aims to deliver a long-range, low-cost X-plane using a wing-in-ground-effect (WIG) ekranoplan-like concept. Artwork released by DARPA shows that the Aurora Flight Sciences concept, which has not been seen before, resembles a more traditional flying boat. The concept features a single hull, high wing and eight turboprops for propulsion. It also looks somewhat similar to Boeing Phantom Works’ Pelican WIG concept from two decades ago.

Aurora Flight Sciences Liberty Lifter concept. Aurora Flight Sciences

In a separate press release published by Aurora Flight Sciences, the company notes that its concept “will employ a robust and adaptive control system designed to meet the challenge of operations to and from the sea surface and at low altitude around waves and obstacles.” Using innovative technologies to avoid operational limitations and dangers posed by large waves has been part of the program since its inception.

General Atomics, on the other hand, has selected a twin-hull, mid-wing design – some concept images of which have previously been released by DARPA. It features 12 turboshaft engines. Unlike in some of the aforementioned previous concept art which show the ten propeller units mounted along the wing in pusher configuration as well as facing forward, the new concepts published by DARPA show the propellers just in the pusher configuration.

This was the original Liberty Lifter video released by DARPA nearly a year ago showing the earlier configuration:

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The design also features upward-opening nose doors to load and offload cargo.

General Atomics Liberty Lifter concept. General Atomics

Phase 1 of the project spans 18 months in total, DARPA’s press release notes, and focuses on defining the aircraft’s design and capabilities with a view to producing a full-scale demonstrator. The 18 months involve six months of conceptual design work, and a further nine months of design maturation. After this, a preliminary design review will be conducted, and, from there, a further three months will be devoted to manufacturing planning and test/demonstration planning reviews. According to General Atomics, an $8 million cost-plus-fixed-fee award has been given for the next six months as the base effort, with the award potentially growing to a total of $29 million if its design is ultimately chosen.

Phase 2 is set to begin in mid-2024, with continued work on the design, manufacturing and demonstration of a full-scale Liberty Lifter X-plane. The press release also indicates that one or more Department of Defense (DoD) and international partners may be brought in to turn the Liberty Lifter demonstrator into an operational vehicle.

“We are excited to kick off this program and looking forward to working closely with both performer teams as they mature their point-of-departure design concepts through Phase 1,” Christopher Kent, DARPA Liberty Lifter program manager is quoted as saying in the DARPA press release. “The two teams have taken distinctly different design approaches that will enable us to explore a relatively large design space during Phase 1.”

Both Aurora Flight Sciences and General Atomics, it should be noted, will need to hit the same criteria in their concepts set out by DARPA. The planned Liberty Lifter X-plane will be similar in capacity, at least, to the C-17 Globemaster III transport aircraft. The vehicle will also include the ability to takeoff and land in Sea State 4 – characterized by wind speeds of 11-16 knots with wave heights ranging from 3-5 feet – as well as perform “sustained on-water operation” up to Sea State 5. The vehicle will also need to be able to fly close to the water in ground effect, with the ability to fly out of ground effect at altitudes up to 10,000 feet above sea level at speeds faster than current sea lift platforms.

As DARPA has noted in the past, one of the main challenges it will address in the Liberty Lifter program is how to operate in turbulent sea states, “by creating high-lift abilities at low speeds to reduce wave impact load during takeoff/landing, and innovative design solutions to absorb wave forces.” The key here is that the vehicle will need to “combine fast and flexible strategic lift of very large, heavy loads with the ability to take off/land in water.”

As we pointed out in our past article on the Liberty Lifter X-plane, its development comes as the U.S. envisions a future conflict with China in the expansive Pacific region. Having a strategic airlift capability that can service virtually any spot in the vast stretches of the Pacific could be a boon for U.S. and allied forces. Its low-altitude flight profile could also provide better survivability in a combat environment that can go from uncontested to contested without warning. In addition, it would not be vulnerable to submarine or traditional anti-ship missile attacks like normal logistics ships.

Being able to move large quantities of fuel, equipment, and personnel to remote locales, especially those that lack traditional runways, could prove critical. It could also help free-up high-flying airlifters for other emerging missions. As it sits now, American airlift capabilities will be taxed to the max during a major conflict in the Pacific. 

Still, this is a very exotic concept, and other, more traditional approaches to aerial access to sea landing areas are being made, including a plan to put a C-130 on floats. So, questioning the chances of the DoD actually moving the Liberty Lifter into production cannot be avoided. Cost, as always, will be a huge factor here. This is a very large flying machine. Making it relatively affordable to produce, even if doing so trades some performance, as DARPA has mentioned, will be a big challenge.

Regardless, DARPA is set on seeing exactly what such a concept could be capable of and is putting its money where its mouth is in that regard. Even if it never makes it into the air, the Liberty Lifter is bound to draw immense interest, just as Ekronoplans like the famous Soviet ‘Caspian Sea Monster’ still do today.