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Military

DARPA's ground-effect X-plane will haul 100 tons of cargo

By David Szondy
February 01, 2024
DARPA's ground-effect X-plane will haul 100 tons of cargo
Artist's concept of the Liberty Lifter
Artist's concept of the Liberty Lifter
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Artist's concept of the Liberty Lifter
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Artist's concept of the Liberty Lifter
The Liberty Lifter update includes new tail and float designs
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The Liberty Lifter update includes new tail and float designs

Aurora Flight Sciences has updated the design of its Liberty Lifter seaborne military heavy-lift transport – a highly efficient X-plane the company is developing for DARPA that achieves bulk lift by using wing-in-ground effect.

Since 2022, DARPA has been developing the Liberty Lifter, which is a project to develop a relatively inexpensive seaplane that has the cargo volume of a C-17 Globemaster III transport aircraft, yet can carry 100 tons of cargo. In addition, it is supposed to have a ferry range of 6,500 nm (7,500 miles, 12,000 km).

Aurora's candidate is in preliminary design Phase 1B of its development cycle, which places special emphasis on risk reduction in the steps for designing, building, launching, and flying the completed X-plane using low-cost manufacturing methods.

This involves Aurora teams building full-scale components, including part of the fuselage, using novel materials and then testing them before assembly. In addition, the company has built test models for water tests in a tow tank at Virginia Tech and is working on sensors for detecting and predicting surface waves.

The Liberty Lifter update includes new tail and float designs
The Liberty Lifter update includes new tail and float designs

One particular challenge is dealing with rough seas because the Liberty Lifter flies using the wing-in-ground effect where the aircraft flies low and gains additional lift by exploiting the air trapped between the wings and the surface of the sea. This is great in calm conditions, but when things get rough, the aircraft needs to be able to compensate to fly safely.

The latest changes to the prop-driven Liberty Lifter include swapping out the t-tail for a pi-tail. Essentially, this means that the stabilizers are held up by a fork-shaped rudder instead of a solid one. According to the company, this allows an aft cargo door while making the airframe more structurally efficient. Another innovation is to move the floats from the side-sponsons on the hull to the tips of the wings for better performance while keeping down costs.

Phase 1B is scheduled for completion in the near future, and the first flight for the Liberty Lifter is expected to take place in 2028.

Source: Aurora Flight Sciences

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MilitaryBoeingDARPAauroraAircraft
16 comments
David Szondy
David Szondy
David Szondy is a playwright, author and journalist based in Seattle, Washington. A retired field archaeologist and university lecturer, he has a background in the history of science, technology, and medicine with a particular emphasis on aerospace, military, and cybernetic subjects. In addition, he is the author of four award-winning plays, a novel, reviews, and a plethora of scholarly works ranging from industrial archaeology to law. David has worked as a feature writer for many international magazines and has been a feature writer for New Atlas since 2011.

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16 comments
MarkHughes4096
It's going to be very interesting to see a modern take on the Ekranoplan flying. I'm looking forward to seeing that.
JeJe
I predict the funding will get pulled and it will never happen. I'm basing that on the past history of very large aircraft projects and the big downsides. Such as the lack of flexibility of a cargo aircraft intended for flight over water but not land.
Strauski
Motors should be ABOVE the wings?
BlueOak
Headline: “…*will* haul 100 tons of cargo”.

That’s some awe-inspiring confidence for a still in rendering design. And it will use “novel materials.” Like wood, a la the Hughes Spruce goose?

Hopefully the company has hired some Soviet era engineering consultants to verofy whether their failures were primarily technology or economic system-related.
clay
Wingtip dragging is gonna be painful; thats a BIG lever. I am surprised the the aspect ratio is so high. I understand the efficiency provided via conventional lift but ground effect has a strong compression element related [moreso] to the direction-of-motion than the span itself. Also, low aspect wings having less lever-arm in rough seas ...tend to be more survivable in wing dipping situations.
jerryd
The engines need to be above the wing, not below it. And the wind needs to be shorter with a longer cord. The pontoon needs to be at the bottom of the wing tip strut or better, a curve in the wing downward at the tip with the float on it.
And these are needed as combat ships, not just cargo that can get to place fast then sit and wait until needed deploying drones, missiles as needed then leave.
Adrian Akau
Use this plane for flights between the Hawaiian islands. It seems durable for rough seas.
Trylon
@JeJe, you didn't read the previous articles. The Liberty Lifter is specified not just to fly in ground effect, but with a service ceiling of 10,000 feet so it can fly over land.

@clay, you're incorrect. Ground effect is proportional to the span of the wing. The longer the span, the higher an aircraft can fly while remaining in ground effect.

The rest of you armchair engineers are funny. Aurora has actually flown a number of manned and unmanned aircraft. I suspect their engineers probably know what they're doing. It's easy to sit back and second-guess companies like Boeing, but I seriously doubt any of you have actually designed or built a flight-qualified aircraft. It's one thing to wonder about design decisions. Quite another to present yourself as smarter than professional aerospace engineers.
SteveG64
Would have thought a lower aspect wing ratio could be more beneficial, with hull and wingtip hydrofoils to assist 'take-off/landing' (smooth through chop). After all it is not meant to work as a normal aircraft in normal air, so why stick with a normal aircraft shape?
DaveWesely
Your pessimism is probably well founded, JeJe. But these times they are a changin. Ships are sitting targets for water based drones. Aircraft are vulnerable to missiles.

Ground effect planes have been a novelty item due to lack of need and stability issues in rough weather. Hopefully the stability issues can be overcome with the faster response times with electric propulsion and electronics.

And now there is a need for this type of aircraft. Difficult to detect with radar since it hugs the water, but as fast as regular aircraft. It's also impervious to torpedoes and water based suicide drones.

In a sense, this is not an aircraft. It's a very fast boat.
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