China’s supersonic submarine

China Supercavitating Submarine

China Supercavitating Submarine

Researchers in China are reporting that they’ve taken a big step towards creating a truly revolutionary submarine. For years, the nation has been dedicated to the expansion of the People’s Liberation Army Navy (PLAN) Submarine Force.

Aside from wanting a fleet that could rival those of other superpowers, the growing fleet is seen as a means of further pressing Chinese territorial and strategic interests in the Pacific. However, this latest development is quite novel, since it involves the development of supersonic submarines.

The technology behind this, which could just as easily be applied to weaponised torpedoes as military or civilian submarines, could theoretically allow a sub to travel from Shanghai to San Francisco a distance of about 9650 km (6,000 miles) – in just 100 minutes. This new advance, developed by a team of scientists at the Harbin Institute of Technology‘s Complex Flow and Heat Transfer Lab, is known as supercavitation – a concept originally developed by the Soviets in the ’60s, during the Cold War.

As is commonly known, objects moving through water have a harder time than those moving through air. While automobiles are only able to travel so fast before succumbing to wind resistance (aka. drag), surface ships and submarines must content with fluid-dynamics, which are much more tricky. Compared to air, water is far more dense and viscous, which means more energy is required to get up to a certain speed. Even the most modern and advanced nuclear submarine cannot travel much faster than 40 knots (74 kph/46 mph), and the same applies to torpedoes. Higher speeds are possible, but would require so much power to make it impractical.

That’s where supercavitation comes into play, a technique devised with the explicit purpose of creating high-speed torpedoes during the Cold War. This technique gets around the drag of water by creating a bubble of gas for the object to travel through. In the hands of the Soviet’s, the research resulted in the Shkval torpedo, which uses a special nose cone to create the supercavitation envelope that allows it to travel through the water at speeds of up to 200 knots (370 kph/230 mph) – much, much faster than the standard torpedoes fielded by the US.

The only other countries with supercavitational weapons are Iran – which most likely reverse-engineered the Russian Shkval – and Germany, the creators of the Superkavitierender Unterwasserlaufkörper (“supercavitating underwater running body”). The US is researching its own supercavitational torpedo, but there’s very little public information available. Meanwhile, China is not only looking to create supercavitating torpedoes, but an underwater vessel.

Unlike previous approaches, which have to be launched at speeds of about 95 km (60 mph) to create the initial supercavitation bubble, the method described by the Harbin Institute of Technology in China uses a “special liquid membrane” that reduces friction at low speeds. This liquid is constantly showered over the object to replenish the membrane as it’s worn off by its passage through water. Once the object gets up to speed, it apparently uses the same gas-through-nose-cone technique to achieve supercavitation.

In theory, supercavitation could allow for speeds up to the speed of sound — which, underwater, is a heady 1,482 meters per second, or 5343 kph (3,320 mph). At that speed, you could go from Shanghai to San Francisco in well under two hours. And for any nation with a nuclear arsenal – i.e. China, Russia, France, the UK, the US – the ability to deploy nuclear missile subs speedily around the world is a big plus. But of course, there are some challenges posed by the concept and any ship that is equipped to run on it.

For one, it is very difficult to steer a supercavitating vessel and conventional methods (like rudders) don’t work without water contact. Second, developing an underwater engine that’s capable of high velocity over long distances is very, very difficult. Jet engines do not work underwater and generally, rockets only have enough fuel to burn for a few minutes. Nuclear power might be a possibility as far as supersonic submarines go, but that’s strictly academic at this point.

Li Fengchen, a professor at the Harbin Institute, says their technology isn’t limited to military use. While supersonic submarines and torpedoes are at top of the list, the same technology could also boost civilian transport, or even boost the speed of swimmers. As Li put it:

“If a swimsuit can create and hold many tiny bubbles in water, it can significantly reduce the water drag; swimming in water could be as effortless as flying in the sky.”

As always with such advanced (and potentially weaponised) technology, it’s hard to say how far away it is from real-world use. Given that this is primarily a military research project, then one can expect that it will remain shrouded in secrecy until it is ready. And if civilian researchers are making good progress, then it’s a fairly safe bet that the military is even further along.

Source: Extreme-Tech – China’s supersonic submarine, which could go from Shanghai to San Francisco in 100 minutes, creeps ever closer to reality
Source: SCMP – Shanghai to San Francisco in 100 minutes by Chinese supersonic submarine

Categories: Defence & Aerospace

Tags: , , , , , , , , , , , , , ,

7 replies

  1. Bravo to China’s military advancement!

    Editor’s Note: Oh wait – they haven’t done it yet…



  1. Thai navy buys 3 Chinese submarines | China Daily Mail

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