Shanghai to San Francisco in 100 minutes by Chinese supersonic submarine

JoeCivvie

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Shanghai to San Francisco in 100 minutes by Chinese supersonic submarine
Chinese eye 'supercavitation' technology as future of underwater travel

http://www.scmp.com/news/china/arti...-chinese-supersonic-submarine?page=2#comments



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

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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.
 
This is in the wrong forum, it's nether a tank, plane or ship.

I understand a similar concept is being used (or has been considered) in aircraft, some fancy plasma stuff creates a pocket around an aircraft.

I just wonder what use a Mach 1 sub is when your enemy (the west) is bombing home with Mach 14 aircraft, kind of makes the technology useless. Oh that and Mach 14 ICBMs will have been delivering pain for a least 14 times faster than the sub, it may find that delivering its payload is a suicide as it's already list the war.

However from a technology point, nice!
 

Cold_Collation

LE
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Also a bit like warp drive in sci-fi, no? Before you hit 'go', you need to set a course that has absolutely nothing in the way... thumping into something at Mach 1'll not be something you'll want to be doing often.
 
Won't somebody think of the whales.
 

seaweed

LE
Book Reviewer
RIP
What about the energy needed to do the work to displace the water around the bubble?
 
Maybe the main message here is that if they can develop steerable, very fast submarines, then their torpedoes are going to be epic.
 
I just wonder what use a Mach 1 sub is when your enemy (the west) is bombing home with Mach 14 aircraft, kind of makes the technology useless. Oh that and Mach 14 ICBMs will have been delivering pain for a least 14 times faster than the sub, it may find that delivering its payload is a suicide as it's already list the war.
I suppose it would depend on the doctrinal problem being addressed - or even if there is one. A superfast submarine wouldn't necessarily have to be a missile boat and the ability to get a hunter-killer in and out of strike range of a carrier group before it could bring ASW weapons to bear would certainly change the CG Commander's risk perception and how the CG operated. It wouldn't really matter if they could hear you coming if nothing they had could hit you.

Of course, since the PLA defence industry was mostly privatised in the 90s, it's also possible that this is about 'industry' rather than 'defence' - or at least defence in the sense we're used to. Getting in on the ground floor of new technology is a long-term PRC strategic aim.
 

rampant

LE
Kit Reviewer
Book Reviewer
Maybe the main message here is that if they can develop steerable, very fast submarines, then their torpedoes are going to be epic.

Steerable at Mach speeds, huge turning circle if it doesn't tear itself apart. More a point at known position and keep going kinda thing I would have thought.
 
That is actually a significant problem. At those speeds, a schoal of mackeral will reduce such a vessel to expensive dust. And you can't predict where the underwater fauna will be..

Interesting point and seeing as I have a lot of boring but essential paperwork to do today I have been procrastinating by thinking about this. Would the bubble not push aside "stuff" up to a certain mass and how much heat would the "wall" of the bubble generate? I presume it would also generate a "hump" on the surface as it travels along even at depth.
Anyway what happened to the trans ocean "vacuum trains" We were promised in the 60'?
 
I seem to remember from school physics, that water cannot be compressed. If that is actually true, then where does all the displaced liquid go and how hot would it be? Can you imagine a super hot tsunami-like bow wave traveling across an expanse of ocean at Mach speeds. You wouldn't need torpedoes or other kinetic weapons. Just hightail it through the water towards your enemy in a straight line then either turn or slam the anchors on just short of the target (5-10 nautical miles should do it) and watch the poor buggers boil.
 

Mattb

LE
I seem to remember from school physics, that water cannot be compressed. If that is actually true, then where does all the displaced liquid go and how hot would it be? Can you imagine a super hot tsunami-like bow wave traveling across an expanse of ocean at Mach speeds. You wouldn't need torpedoes or other kinetic weapons. Just hightail it through the water towards your enemy in a straight line then either turn or slam the anchors on just short of the target (5-10 nautical miles should do it) and watch the poor buggers boil.
I'm no sailor but I don't think that a largish wave that's quite hot would overly bother a frigate or a destroyer.

It may be technically feasible to create a machine that can run at supersonic speeds underwater, but why would you need that as a passenger craft? We've had the ability to carry stuff at twice the speed of sound over long distances in a machine that can turn and won't have a whale-collision issue - it's called Corcorde.


Talking out of my bum, via a mobile telephone.
 
I'm no sailor but I don't think that a largish wave that's quite hot would overly bother a frigate or a destroyer.

It probably would if it was travelling at 500 knots.

It may be technically feasible to create a machine that can run at supersonic speeds underwater, but why would you need that as a passenger craft? We've had the ability to carry stuff at twice the speed of sound over long distances in a machine that can turn and won't have a whale-collision issue - it's called Corcorde.


Talking out of my bum, via a mobile telephone.

I thought about that too. You wouldn't need to man it, so you could allow for greater stresses and strains than a human could withstand. You also wouldn't need those very wasteful and expensive life support systems. A stand-off supersonic torpedo. There would be no requirement whatsoever for explosives.
 

Mattb

LE
It probably would if it was travelling at 500 knots.
Not unless the amplitude was great enough. I get hit by waves moving at over 3,000 mph every time I go swimming and I always seem to survive.

Any force big enough to make a frigate-smashing wave would almost certainly smash the craft that made it.



Talking out of my bum, via a mobile telephone.
 

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