More information on the "Liberty Lifter" Initiave

 

Back in June I did a "Post" about the Liberty Lifter, well more information came out about it from DARPA,

    I snagged this from my 3rd party email again.

Concept art of DARPA’s future Liberty Lifter vehicle. (Image provided by DARPA.)

Updated 12/1/2022 at 1:27 pm ET with comment from DARPA.

WASHINGTON — One of the Pentagon’s key research and development agencies has tapped General Atomics ASI to work on its “Liberty Lifter” program, a relatively new initiative aimed at transforming the military’s airlift and sealift capabilities.

The contract from the Defense Advanced Research Projects Agency is worth $8 million, according to the Pentagon’s daily contract announcement for Nov. 25. The Pentagon statement did not elaborate on the type of work included in the contract, but said $6.2 million of the award would come from “fiscal 2022 research and development funds.”

On Thursday, a DARPA spokesman confirmed the contract is for conceptual design work related to the program. A General Atomics ASI spokesman declined to comment.

The Liberty Lifter program, announced earlier this year, aims to design a “long-range, low-cost X-plane capable of seaborne strategic and tactical lift,” DARPA said at the time. It’s envisioned to be similar in size to a C-17 Globemaster, weighing between 500,000 and 600,000 pounds, and cost roughly $340 million per plane.

Alexander Walan, a DARPA official overseeing the program, told Breaking Defense in an interview in May that a concept known as the “wing-in-ground” effect is critical to its design.

“If you’ve ever been on an airliner or watched a 737 land, sometimes they come in close, and then they almost kind of like go to a hover,” he said. During those moments of low altitude updraft, the aircraft experiences less drag and can more easily maintain its remaining altitude — a phenomenon DARPA hopes to stretch for long distances. “For very long-range operations, a few percentage points [of increased lift and reduced drag] actually start really adding up” in terms of fuel efficiency.

For the Pentagon’s purposes, DARPA thinks this physics trick could result in an aircraft capable of operating more efficiently than traditional cargo planes while traveling overseas as well as being able to land in large bodies of water rather than established runways.

There are a variety of challenges in pulling off the Liberty Lifter concept, however. For example, rough waves could result in turbulence on the plane, which would eat into any fuel efficiencies being gained through the “wing-in-ground” effect.

Although the WIG concept has been known for some time, it has proven difficult to master. The Soviet Union made multiple attempts at such a craft, but largely came up short of designing a vehicle ready for mass production.

“The Soviets really showed how not to do this, like a lot of things, right?” Walan told Breaking Defense.

One of those mistakes was the fact the Soviets designed a plane only capable of flying using the “wing-in-ground” effect. Walan said DARPA would not make the same mistake and envisions Liberty Lifter as capable of flying at traditional altitudes when necessary.

 

Liberty Sized Lifter, a DARPA proposal

 This is something that I snagged from the Aviation stuff that shows up in my email from 3rd party sources.  This has interesting ramifications especially with China as a peer adversary in the near future and the Pacific being a big waterpark, and the islands we control are far less than there were during WWII. The ability to deliver freight and goods over water quickly has strategic implications, but also having control of the strategic airspace is a factor, can't have one of these things shot down by a "Chinese J20" or something similar would be bad.

 

New DARPA projects come about for various reasons, but sometimes they start with an impossible question. Five years ago, Alexander Walan, a program manager for the agency’s Tactical Technology Office, started asking if it was possible to design an ocean-crossing cargo vessel with a 100-kt. cruise speed.

“The short answer was: not really,” Walan tells Aviation Week.

• Liberty Lifter concept unveiled by DARPA
• Daylong Pacific crossings sought with 80-ton loads

By pursuing that line of inquiry for several years, however, Walan settled on what became the newly unveiled Liberty Lifter concept. Starting with a $31 million budget request for fiscal 2023, DARPA hopes to demonstrate a C-17-size, seagoing strategic airlifter by 2028.

In fact, DARPA’s proposed design calls for a hybrid configuration. The Liberty Lifter would be a wing-in-ground-effect aircraft that skims on a ground-effect air cushion over the tops of waves at up to 200 kt., but would also be a flying boat capable of ascending up to 10,000 ft.

If the Liberty Lifter concept works in five years, the U.S. military would have the option to field a new type of cargo transport and amphibious assault ship. The seaborne airlifter would cross the Pacific Ocean in about a day—not 2-3 weeks, as required for a seagoing freighter. The DARPA concept also could land and take off from bodies of water rather than the easily targeted runways and dirt strips used by Boeing C-17s.

That unique operational profile is the entire point for a military reorienting itself to strategic competition in the Indo-Pacific area, but it also creates an organizational dilemma. As the project gets started, DARPA officials are not yet clear on whether the operator for the Liberty Lifter should be the Air Force’s aircraft-focused Air Mobility Command, the Navy’s ship-oriented Military Sealift Command, or both.

“We’re probably doing something right if the services like it but can’t figure out where it fits,” Walan says. “That means it’s new and different. So that’s an opportunity and a risk.”

The concept evokes the Cold War-era “ekranoplan” fleet, which included the Soviet Union’s A-90 Orlyonok transports and Lun-class anti-ship missile launchers, but the Liberty Lifter comes with a major difference. Due to a design limited to ground-effect flight only, the Soviet vessels were limited to flying over calm seas.

DARPA’s concept calls for operating in ground effect over waves up to 18 ft. high, covering about 85-90% of maritime conditions, Walan says. Moreover, if the military decided to move a Liberty Lifter from the Atlantic Ocean to the Gulf of Mexico, it would be better to fly overland rather than around the tip of Florida, he adds. So DARPA added a requirement for up-and-away flight to 10,000 ft.

Bidders for a Phase 1 study could propose alterations, but DARPA came up with a design for a Stratolaunch Roc-style twin-fuselage arrangement, with canards in front of a long wing powered by 10 turboshaft engines positioned on the trailing edge. Most ekranoplan designs position engines in front of the wing to stimulate the ground-effect airflow, but DARPA rejected this approach. Mounting the engines on the wing’s trailing edge protects the blades and turbines from corrosive saltwater spray, and the Liberty Lifter’s wings can generate enough of an air cushion for ground-effect flying anyway, Walan says.

As the concept blurs the line between aircraft and boat, so does DARPA’s concept for the structure. The Liberty Lifter should be built from medium-grade aluminum, splitting the difference between lighter aerospace alloys and cheaper, heavier metal forms used in ships. A risk reduction project by DARPA manufactured a center section wing using 3D-printed aluminum panels, which were joined using friction stir welding, Walan says.

The proposed amphibious aircraft will need an advanced control system, including fly-by-wire and wave-monitoring sensors. Any given sea state involves more than simply the height of the waves,  including the distance between the waves and the interaction between them. “If I know what the waves look like—not only the crests, but also wavelength, etc.—I can optimize how high I want to fly,” Walan says.

The DARPA project comes amid a revival of interest from startup companies in wing-in-ground-effect vehicles. Although Flying Ships and Regent have held discussions with DARPA, both companies say they are not participating. For his part, Walan expects industry teams composed of aviation and maritime companies.

“We kind of gave a heads-up last year that this might be coming,” Walan says, “to let people start working those relationships.”