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  • Dec 21, 2014
  • Updated: 8:02am
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DEFENCE

Shanghai to San Francisco in 100 minutes by Chinese supersonic submarine

Chinese eye 'supercavitation' technology as future of underwater travel

PUBLISHED : Sunday, 24 August, 2014, 5:22am
UPDATED : Sunday, 24 August, 2014, 5:22am
 

China has moved a step closer to creating a supersonic submarine that could travel from Shanghai to San Francisco in less than two hours.

New technology developed by a team of scientists at Harbin Institute of Technology's Complex Flow and Heat Transfer Lab has made it easier for a submarine, or torpedo, to travel at extremely high speeds underwater.

Li Fengchen, professor of fluid machinery and engineering, said the team's innovative approach meant they could now create the complicated air "bubble" required for rapid underwater travel. "We are very excited by its potential," he said.

Water produces more friction, or drag, on an object than air, which means conventional submarines cannot travel as fast as an aircraft.

However, during the cold war, the Soviet military developed a technology called supercavitation, which involves enveloping a submerged vessel inside an air bubble to avoid problems caused by water drag.

A Soviet supercavitation torpedo called Shakval was able to reach a speed of 370km/h or more - much faster than any other conventional torpedoes.

In theory, a supercavitating vessel could reach the speed of sound underwater, or about 5,800km/h, which would reduce the journey time for a transatlantic underwater cruise to less than an hour, and for a transpacific journey to about 100 minutes, according to a report by California Institute of Technology in 2001.

However, supercavitation technology has faced two major problems. First, the submerged vessel has needed to be launched at high speeds, approaching 100km/h, to generate and maintain the air bubble.

Second, it is extremely difficult - if not impossible - to steer the vessel using conventional mechanisms, such as a rudder, which are inside the bubble without any direct contact with water.

As a result, its application has been limited to unmanned vessels, such as torpedoes, but nearly all of these torpedoes were fired in a straight line because they had limited ability to turn.

Li said the team of Chinese scientists had found an innovative means of addressing both problems.

Once in the water, the team's supercavitation vessel would constantly "shower" a special liquid membrane on its own surface. Although this membrane would be worn off by water, in the meantime it could significantly reduce the water drag on the vessel at low speed.

After its speed had reached 75km/h or more the vessel would enter the supercavitation state. The man-made liquid membrane on the vessel surface could help with steering because, with precise control, different levels of friction could be created on different parts of the vessel.

"Our method is different from any other approach, such as vector propulsion," or thrust created by an engine, Li said. "By combining liquid-membrane technology with supercavitation, we can significantly reduce the launch challenges and make cruising control easier."

However, Li said many problems still needed to be solved before supersonic submarine travel became feasible. Besides the control issue, a powerful underwater rocket engine still had to be developed to give the vessel a longer range. The effective range of the Russian supercavitation torpedoes, for example, was only between 11 km and 15 km.

Li said the supercavitation technology was not limited only to military use. In future, it could benefit civilian underwater transport, or water sports such as swimming.

"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," he said.

Besides Russia, countries such as Germany, Iran and the United States have been developing vessels or weapons using supercavitation technology.

Professor Wang Guoyu, the head of the Fluid Mechanics Laboratory at Beijing Institute of Technology who is leading another state-funded research project on supercavitation, said the global research community had been troubled for decades by the lack of innovative ideas to address the huge scientific and engineering challenges.

"The size of the bubble is difficult to control, and the vessel is almost impossible to steer," he said. While cruising at high speed during supercavitation, a fin could be snapped off if it touched the water because of the liquid's far greater density.

Despite many scientists worldwide working on similar projects, the latest progress remains unclear because they are regarded as military secrets.

Wang, a member of the water armament committee of the China Society of Naval Architects and Marine Engineers, said even he had been kept in the dark about recent supercavitation developments in China.

"The primary drive still comes from the military, so most research projects are shrouded in secrecy," he said.

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This article is now closed to comments

ianson
Publishing this science speculation as headline news is very poor journalism. This is so remote from reality, its proper place is buried deep in science pages. And, by the way, which do you want, the speed of sound OR 5,800 km/hour? Make up your mind: the former is only about 1,200 km/hour. Giving this report such unwarranted prominence stinks of the CCP propaganda machine, once again obligingly facilitated by Comrade Editor Wang.
nathan_kaiser
This does not even reach the quality of News of the World. Has this been copied straight from The Onion again? Since when does SCMP practice this as well? Did SCMP completely drop the part "fact checking"?
53f91acf-0b2c-46a0-b738-4c550a320968
Try hitting a whale at 370 km/h
53fbe32f-6b78-4e4a-87a2-52ad0a3209cb
You are wrong. As the article says, it is the speed of "sound in water" which is around 4.3 times faster than in air depending on temperature, density and impurities.
bagelbagel
Sort out the high speed train first......
baysidedweller
I think you are assuming speed of sound is identical in air and in liquid.
Speed of sound in air and in liquid are different - ****en.wikipedia.org/wiki/Speed_of_sound and it also depends on the depth, salinity of the seawater and water temperature.
Speed of sound in seawater is close to 5616km/hr at 0 depth, 34 percent salinity and 20 degrees C- ****keisan.casio.com/exec/system/1258122391.
I don't believe that it is theoretically impossible, but whether it is possible in real life is another matter.
I would not "pooh pooh" the idea yet. Maybe some other "unintended and positive" commercially viable products can come from the research, like commercial products from NASA research - ****en.wikipedia.org/wiki/NASA_spin-off_technologies
michaelhctam@gmail.com
Jealous Westerners bitter about the fact that their nations and civilization is declining and China is rising. China now is what the USA is like during the turn of the 20th century. Its our time now.
michaelhctam@gmail.com
why do all these westerners want to see China fail? You should embrace us, become part of us, we can forge a new Empire together. Unless, you want to be the forest barbarians that we eventually economically conquer and assimilate.
53faa52c-6138-4b44-bd66-08ef0a3209ca
Traveling at such speeds underwater would most likely be devastating to sea life. This is an insane idea.
captam
Note from the writer: This report should have been published on 1st April.
Sorry its a bit late. Will try and get it right next time.
But, seriously why San Francisco? What's wrong with Pearl Harbour if you want to start a world war?

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