Chinese engineers follow the Sea Dragon with new submersible that can ‘fly’ through water like a plane in the air

Stephen Chen

Chinese engineers say they are developing a radical design for a super-fast robot submersible which the project leader, who worked on the manned deep-sea vessel Jiaolong, or Sea Dragon, claims can “fly” in water like a plane travels through the air.

At 3 metres (9.8ft) long, the prototype consists of a cigar-shaped body, with a guidance system in the bow and a jet plane style rudder and a propeller in the stern.

Outriggers house batteries and two more propellers. These are attached to the body by wing-like planes that the developers said will give the vessel the kind of lift in water that takes an aeroplane into the air and back to the earth.

Developers said the prototype will be capable of 10 knots and could dive to a depth of 1,000 metres (3,281 feet) – or surface from that depth – at about three metres a second, taking about 5½ minutes.

Professor Liu Kaizhou, lead scientist of the project at the Shenyang Institute of Automation, part of the Chinese Academy of Sciences in Liaoning province, said the design had great potential.

If a traditional submarine was like an air balloon, he said, the prototype was like an aircraft. “It is technically flying, fast and freely, like a plane for the water.”

The prototype has 20 major components on board, including a computer, and communications and surveillance equipment. These were all developed and tested by the team, but getting them to work together posed some unexpected challenges, Liu said, meaning the transition to operations in a tough marine environment was some time away.

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“We aim to make the first open sea test in about a year,” he said.

The submersible can be powered by conventional batteries or a chemical engine that mixes lithium and sulphur hexafluoride to produce heated steam for electrical generators – an energy source often used by torpedoes.

Funded by the Ministry of Science and Technology from 2017, the project was driven by China's growing ambition to become a superpower in the world's oceans.

The team said their submersible had the potential to become the backbone of China’s search-and-rescue operations at sea, naval intelligence gathering, high-precision sea floor mapping, or to transport minerals from the seabed to the surface.

Professor Liu Kaizhou (left) with colleagues Ye Cong and Yang Bo, was instrumental in the success of China’s Jiaolong manned submersible. Photo: Xinhua

Professor Du Tezhuan, a researcher in fluid dynamics at the Institute of Mechanics of the Chinese Academy of Sciences in Beijing, said the design was a bold one but it posed the research team many hard questions.

The density of water was much higher than that of air, he said, which meant the vessel would encounter more drag and would need a strong power source.

“Without sufficient speed, the lift will be weak, and to reach high speeds, lots of energy will be needed. Flying in water is not as easy as flying in the air,” said Du, who was not involved in the project.

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“But in theory it should work. It is worth a try.”

Liu – who led the design of the autopilot system that can take the Jiaolong to depths of more than 7,000 metres (23,000 ft) – said that after tests on the prototype were complete, other innovations were possible. These included covering the vessel with air bubbles to reduce friction.

“This technology is brand new,” he said. “We are in uncharted water and we are excited by the challenges.”

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