These Two Designs Were Cleared for DARPA’s Liberty Lifter Flying Boat, Love the Twin-Hull

In May 2022, the research agency announced what is now known as the Liberty Lifter. The initial details spoke of an aircraft capable of flying 100 feet (30 meters) above the surface of the water, but also packing the ability to climb to 10,000 feet (3,000 meters) if the need arises.

The main task of the plane in the service of the American military would be to transport cargo and why not, even troops. For that to happen, last year’s plans talked about the Liberty Lifter having the ability to carry over 100 tons of cargo, a tad more than what the current C-17 Globemaster III is capable of lifting.

This week, DARPA made it obvious to anyone how serious it is about this project by announcing two competing designs. They are being drawn up by five companies working in teams, and we should have a more complete look at them by sometime next year.

The first team is that of General Atomics and Maritime Applied Physics Corporation. People working on this project on behalf of these companies have come up with a twin-hull, mid-wing design, out of the need of optimizing the plane’s performance while on the water. Their Liberty Lifter is to be powered by no less than 12 turboshaft engines.

The second team of companies is a trio comprising Aurora Flight Sciences, Gibbs & Cox, and ReconCraft. Their plan is to come up with something that looks a lot more like a flying boat, with a single hull and massive wings stretching from it. Just eight engines are needed to power this thing, at least on paper.

DARPA has tasked these groups to come up with designs for the full-scale Liberty Lifter demonstrator. They’ll have to imagine solutions that allow takeoff and landing in Sea State 4 conditions (wave height between 1.25 and 2.5 meters/4 to 8 feet), but also sustained operation on the surface in Sea State 5 conditions (waves between 2.5 and 4 meters/8 to 13 feet high).

In all, the companies involved will have six months at their disposal for conceptual design work, followed by nine more months for design maturation. Once that is out of the way, a preliminary design review will follow, and if all is well, manufacturing and testing planning will begin.

DARPA intends to move to Phase II of the Liberty Lifter project sometime next year. It is then when we should expect detailed design, manufacturing, and demonstration of a full-scale flying boat such as the ones shown this week. For these tasks, the agency says more partners will likely get involved.