DARPA Liberty Lifter aims to bring back heavy-lift ground effect seaplanes
DARPA has launched a new "Liberty Lifter" program to design, build and test a highly-efficient wing-in-ground effect aircraft for transporting "very large, heavy loads" over long distances without runways. Prototypes could fly as early as 2027.
The wing-in-ground effect has seen a bit of a mini revival over the last few years. There are a few players trying to get ground effect vehicles (GEVs) into commercial circulation – notably Singapore's Wigetworks, with its Airfish-8 and Boston's Regent, which has drawn in considerable funding and pre-sales to build a prototype of its fully electric, 12-passenger Viceroy seagliders.
All of these aircraft, as well as the Liberty Lifter and Russia's famous WW2 Ekranoplan program, aim to make use of a neat bit of physics: when a plane flies very close to the ground – at an altitude less than half of its own wingspan – it can ride on a cushion of high-pressure air between the wing and the surface, gaining additional lift while reducing lift-induced drag. This can make these things extremely efficient – flying at an altitude around 5 percent of the wingspan can get you from A to B up to 2.3 times more efficiently.
DARPA likes the idea because ground-effect seaplanes could get big, heavy cargo from A to B much faster than ships, without the need for large ports, or the enormous runways and ground-based logistics required by large cargo planes. A Liberty Lifter could take off from any given body of water, and put down on any other, without any infrastructure requirements, greatly simplifying the logistics of moving big, heavy military gear around the place.
For the Liberty Lifter program, DARPA is looking for designs that are:
- Capable of taking off and landing at low speeds on turbulent seas
- Capable of carrying payloads over 100 tons
- Capable of delivering operational range figures over 7,500 km (4,660 miles)
- Capable of operating at sea for weeks at a time without needing land-based maintenance
- Capable of reducing the risk of collisions when operating at high speeds in congested areas
- Cheap to build, using low-cost materials rather than exotic, lightweight materials
- Capable of sensing and avoiding large waves, and intelligently handling the takeoff and landing processes accordingly
While these planes will presumably spend most of their time flying in ground effect, DARPA also wants them to be capable of sustained flight at altitudes up to 10,000 ft (3,050 m), so they're not restricted by the need to stay over water.
According to IEEE Spectrum, DARPA is prepared to award US$15 million to develop up to two concepts. System-level critical design reviews are scheduled for 2025, and the first full-scale prototype could fly as soon as 2027.
Check out a video below.