The Pentagon has awarded contracts to develop two types of heavy-lift planes that would use a phenomenon called “ground effect” to carry 100 tons of troops and weapons at a cruising altitude of just 30 meters.
China has deployed thousands of long-range, precision guided missiles as part of its strategy to keep Taiwan’s allies from getting close to Taiwan and China — if Beijing decides to invade Taiwan. These missiles include long-range anti-air missiles that can be fired from ground-based launchers or from forward-operating bombers and attack jets. China also claims that some of the missiles in its arsenal are capable of hypersonic speeds and of hitting moving ships hundreds of kilometers beyond Taiwan. These huge anti-ship ballistic missiles have been dubbed “carrier killer” missiles, and the Pentagon seems to be taking China’s claims seriously.
One reaction to the possibility that U.S. warships and warplanes would not be able to get close to Taiwan in the opening phases of a conflict, is a comprehensive new plan called Force Design 2030. This plan calls for the insertion of U.S. Marine Corps units on Japanese islands close to Taiwan before these islands can be invaded by Chinese forces. Named “Marine Littoral Regiments,” these units would differ from traditional Marine units in terms of weaponry and tactics. The idea is for the Marines to “stand in” and help to defend Japan’s frontline islands when a Chinese invasion of Taiwan seems imminent, rather than wait for the conflict to start before acting.
By being dug in next to Japanese defenders on Japanese frontline islands like Yonaguni, which lies just 110 kilometers from Taiwan, these Marines would be able to defend the islands while also using precision-guided missiles to hit Chinese warships operating around Taiwan, as well as PLA forces that might be establishing a beachhead on Taiwanese soil.
The big challenge would be to get large numbers of Marines and their weapons — including large anti-ship missiles and their launch trucks — to far-flung islands at short notice. For this reason, the Marine Corps has been asking for a new, smaller type of amphibious landing ship since 2020. The idea is to use more and smaller landing ships that make smaller targets and can disperse over a wide area to improve survivability. However, these “Light Amphibious Warships” have been put on the back burner as the Navy’s shipbuilding budget has been eaten up by more pressing items like nuclear submarines. Plans to buy the first version of this new type of ship have been pushed back to 2025.
Meanwhile, the Pentagon’s research arm, DARPA, has started work on a much more novel way to get Marine Littoral Regiments to their frontline islands before and during a conflict. DARPA announced last Thursday that it has awarded contracts to two aerospace companies to design and build prototypes of two different concepts for large propeller-driven airplanes that can use the magic of “ground effect” to carry 100 tons of troops and cargo over thousands of kilometers.
Ground effect is an additional lifting force that is created when a helicopter blade or airplane wing gets close to the ground. It acts like an air cushion and is caused by the distortion of the airflow below an airplane because of the proximity of the ground. This effect can be a headache for pilots, as it lets the plane glide over the landing strip for too long, forcing the pilot to balance the risk of overshooting the runway with the risk of pushing the nose down too fast and breaking off the plane’s nose wheel.
Yet it is this exact ability to glide on an “air cushion” that makes ground-effect planes so useful, as they consume a lot less fuel while flying in ground effect. The advantages of such planes are that they can carry heavier loads over longer distances than other cargo planes, and they can move a lot faster than the 28 kilometers per hour that the proposed Light Amphibious Warship would be expected to go. Airplanes that are designed to cruise with their wings permanently “in ground effect” are called “wing in ground effect” (WIGE) airplanes. DARPA’s winning WIGE plane would have to be able to carry two amphibious troop carriers or six 20-foot cargo containers, while also being able to “jump” over mountainous islands by climbing to an altitude of 10,000 feet (3,000 meters) when needed. Most importantly, the winning WIGE flying boat would be able to take off from water at one beach and fly to another.
DARPA says it envisions that the eventual winning design would cost a lot less to build than the $340 million needed to buy the C-17 Globemaster III, which it would be competing with in terms of cargo capacity. The idea is to use low-cost manufacturing similar to ship fabrication to build a cheap but functional heavy lifter that does not need a runway or port to operate from, as it would be able to land, load and unload at any beach on the planet. So, it wouldn’t just be a lot cheaper than the C-17 to build and operate, but it would also be a lot more flexible in oceanic theaters.
The Soviet Union built a prototype of its own sea-skimming, “wing in ground effect” plane in the 1980s. Dubbed the “Ekranoplan,” the large flying boat’s official name was the “Lun” and it required eight large turbojet engines to power it. The Lun could carry some cargo internally in addition to the six huge launch pods for Soviet-era “Sunburst” anti-ship missiles that it carried on its back.
In contrast to the Lun, DARPA’s first concept — contracted to General Atomics — currently looks like a massive wing with two distinct hulls separated by the middle part of the wing. DARPA calls it “a twin-hull, mid-wing design to optimize on-water stability and seakeeping,” and it employs distributed propulsion using 12 turboshaft engines fitted on the rear edges of the three large wing segments.
DARPA’s other concept was contracted to Aurora Flight Sciences. This concept currently looks more like a traditional flying boat — with a single hull, a high wing and eight turboprop engines fitted at the front edge of the wing.
DARPA calls the proposed plane the “Liberty Lifter,” echoing the “Liberty ship” of World War II. These Liberty ships were large cargo ships that were designed to be built very cheaply and very fast, resulting in 2,711 being built in a very short period of time. With the Marine Littoral Regiments currently facing a big job without a ride to work because of budget issues, the Navy would be hoping that the eventual “Liberty Lifter” would be as cheap and fast to build as the Liberty ship.
DARPA says it expects the two concept demonstrators to be ready for construction by mid 2024. If the final products are ready for use by the time they are needed, the Liberty Lifters would be able to carry troops and their equipment much faster than an amphibious ship can. It would also be able to glide over wartime dangers like torpedoes and sea mines.
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