DARPA, from a team led by General Atomics and Aurora Flight Systems, has decided to develop two radically new Liberty Lifter seaplane wing-in-ground effects full-fledged maritime strategic and tactical heavy-lift demonstrators. We chose a different design.
In 2022, DARPA announced a project to develop an aircraft called the Liberty Lifter. It has the size and capacity of a C-17 Globemaster III transport aircraft, but can lift over 100 tons of payload. Given that the C-17 can only manage about 77 tons on its best days and the Liberty Lifter assumes he is a seaplane with a ferry range of 6,500 nm (7,500 miles, 12,000 km), this is quite impressive. That’s enough to fly from the North Pole to the Equator with a little extra headroom.
The secret to this performance lies in one of the great mysteries of the Cold War: the esoteric aerodynamic phenomenon known as the ‘ground effect’ or ‘inside wing effect’.
In the late 1960s, American spy satellites monitoring the Soviet Union spotted a strange and very large aircraft sailing in the Caspian Sea. Dubbed the Caspian Sea Monster by intelligence agencies, the craft weighed more than her 500 tons, probably because it had thick, stubby wings that couldn’t support it in the air, so its head fell off. was bothering me.
The mysterious spacecraft turns out to be an ekranoplan. This was a series of ground effect vehicles developed by the Soviet military that could fly at very low altitudes to avoid radar detection while carrying heavy missile loads.
The key was the very low altitude. Ground effect occurs when an aircraft is flying very close to the ground or preferably water. Without going into the technical details, when the plane is moving forward at low altitude, it works as if there is a cushion of air trapped between the plane and the ground. As a result, drag is reduced and lift is increased, allowing aircraft to have smaller wings, carry heavier loads, or a combination of both.
This is why the Caspian sea monsters are so large and can fly with stubby wings. Unfortunately, such ground effect craft have severe limitations. One of the biggest of these is that it does best flying over flat, calm water and doesn’t like rough seas.
DARPA’s Liberty Lifter project not only overcomes some of these shortcomings, but also takes the technology a step further, enabling it to carry heavy loads over long distances and take off and land on water to eliminate the need for runways. We want to create an aircraft that can , can be assembled using inexpensive shipbuilding techniques and can operate for weeks without maintenance.
DARPA
Additionally, it must be able to land and take off in Sea State 4 where waves reach 8.4 feet (2.5 m) and operate on Sea State 5 water with waves up to 13.1 ft (4 m). It must also be capable of functioning as a low-altitude aircraft capable of flying from ground effect to altitudes of 10,000 feet (3,000 m) above sea level.
In Phase 1 of the project, Gibbs & Cox and ReconCraft lead Aurora Flight Sciences are developing a conventional flying boat-like aircraft with a single hull, high wings and eight turboprop engines. . Meanwhile, General Atomics and Maritime Applied Physics Corporation have opted for a more exotic twin-hull, mid-wing design for better water stability and seaworthiness, while propulsion is provided by 12 turboshaft engines. I am working on a design.
Phase 1 lasts 18 months with 6 months of conceptual design work and 9 months of design maturity planned before results are submitted for preliminary design review and test/demo plan review 3 months later It has been. This will be followed by Phase 2 in 2024 to design, manufacture and demonstrate a full-scale Liberty Lifter X-Plane once the design is successful.
Christopher Kent, DARPA Liberty Lifter Program Manager, said: “We are excited to begin this program and will be working closely with both performer teams to mature the starting point design concept throughout Phase 1. “The two teams took distinctly different design approaches to allow Phase 1 to explore a relatively large design space.”
Source: DARPA
