China Claims to Have Developed a Radical New Stealth Technology for Its Submarines

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The Chinese People’s Liberation Army Navy (PLAN) claims to have developed new electrically-powered pump-jet propulsor that would theoretically be much quieter than any current generation Western submarine propulsion system.

Unlike a conventional propulsor design—which is turned by a mechanical drive shaft—China’s rim-driven system is powered by an electrical motor embedded in the propulsor’s shroud.

“A rim-driven pump-jet has a ring-shaped electrical motor inside the pump-jet shroud, which turns the vane rotor inside the pump-jet cavity to create thrust,” as South China Morning Post reporter Minnie Chan described the system.

Theoretically, without a drive-shaft, a submarine should be much quieter, and thus much more difficult to detect. Additionally, the Chinese are claiming that the new propulsor could reduce cavitation, which would also significantly help to improve a submarine’s acoustical signature performance.

“This is one of our work team’s first world-leading projects, which has been used on [China’s] next-generation nuclear submarines,” PLAN Rear Admiral Ma Weiming told China Central Television in May according to SCMP.

“[Our technology] is now way ahead of the United States, which has also been developing similar technology.”

Ma told the Chinese television channel that the new rim-driven pump-jet will be fitted onto the PLAN’s next-generation nuclear submarines. Those vessels might include versions of the nuclear-powered Type 095 attack submarines and the Type 096 ballistic missile submarines. However, PLAN has not confirmed which of its new submarines might receive the new propulsor technology.

The U.S. Navy uses pump-jet propulsor technology onboard its Improved Los Angeles, Seawolf and Virginia-class attack submarines. The U.S. Navy is also planning to use a pumpjet propulsor onboard its forthcoming Columbia-class nuclear-powered ballistic missile submarines. The Columbia-class will use integrated electrical propulsion with a permanent-magnet motor turning the submarine’s drive shaft.

Developing a shaftless propulsion system is something akin to the holy grail of submarine propulsion. U.S. naval experts are skeptical of the Chinese claims.

“I read this earlier this morning and concluded that the PLAN propaganda machine was busy on July 4th,” Bryan McGrath, managing director of the FerryBridge Group naval consultancy, told me.

But while McGrath is skeptical, if the Chinese claims prove to be true, it could be something significant.

“Yes, something...if genuine,” McGrath said.

“And there is no question in my mind that the undersea advantage we enjoy will come under increasing pressure from PLAN capabilities. But quieter that U.S. subs? No.”

Thus, if the Chinese have managed to successfully develop a rim-driven pumpjet propulsor that works in a real world operational setting, it would be a significant development. It would mean that the PLAN is making genuine progress in developing novel submarine technologies and that it is starting to catch up. But there is more to a submarine’s acoustical stealth than just the propulsion system, and it will take time and a lot of trial and error before the PLAN can match or exceed American capabilities in the undersea domain.

China Claims to Have Developed a Radical New Stealth Technology for Its Submarines
 
Pump-jet propulsor is not new. Both Vanguard and Astute have them.
Its a slightly different type of propulsion design. one driven by rim instead of a shaft. I think the article is mis-reporting, its a rim-driven propulsion alright, not exactly a pump-jet propulsion.
 
Its a slightly different type of propulsion design. one driven by rim instead of a shaft. I think the article is mis-reporting, its a rim-driven propulsion alright, not exactly a pump-jet propulsion.
It's magnetically driven, no mechanical contact. The Soviets were busy stealing secrets in the '80s to try and catch up and bankrupted themselves doing so. Vanguard and Astute also have no cooling pump for the reactor.
 
It's magnetically driven, no mechanical contact. The Soviets were busy stealing secrets in the '80s to try and catch up and bankrupted themselves doing so. Vanguard and Astute also have no cooling pump for the reactor.

I don't think that is the case pal. That kind of propulsion is called MHD drive.
Magnetohydrodynamic drive - Wikipedia

This one is very much mechanical, though it reduces noise by not having a shaft and obtains thurst by driving water with a rim driven blades. This causes less cavitation but it is less efficient as well.

BTW, british subs have Pump-Jet based propulsion. Not MHD. MHD is more of a pipe-dream than reality.
 
I don't think that is the case pal. That kind of propulsion is called MHD drive.
Magnetohydrodynamic drive - Wikipedia

This one is very much mechanical, though it reduces noise by not having a shaft and obtains thurst by driving water with a rim driven blades. This causes less cavitation but it is less efficient as well.

BTW, british subs have Pump-Jet based propulsion. Not MHD. MHD is more of a pipe-dream than reality.
It is the case, I would know, the pump jet is driven magnetically. Why do you feel it's a pipe dream, even most new wind turbines are using direct magnetic drive? Since when has China developed anything that they haven't copied?
 
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It is the case, I would know, the pump jet is driven magnetically. Why do you feel it's a pipe dream, even most new wind turbines are using direct magnetic drive? Since when has China developed anything that they haven't copied?

Oh well, difference between MHD and Pump Jet is what you have correctly identified as "no mechanical contact" : I guess you meant no moving parts . MHD uses no moving parts per say -- besides water of course -- and yet provides propulsion. Pump-Jet propulsion does have moving parts.

Pump-jet - Wikipedia

Pump-jet may be 'driven magnetically', in the sense of being driven by an electric motor or otherwise. MHD does not have a electric motor per-say. It uses MHD properties of salty water to propel the sub.

And yes MHD drive is a pipe-dream. Jet-Pumps are not. Jet-Pumps are used a lot in lifting water from bore-well in everyday life.

Hope that clarifies.
 
Oh well, difference between MHD and Pump Jet is what you have correctly identified as "no mechanical contact" : I guess you meant no moving parts . MHD uses no moving parts per say -- besides water of course -- and yet provides propulsion. Pump-Jet propulsion does have moving parts.

Pump-jet - Wikipedia

Pump-jet may be 'driven magnetically', in the sense of being driven by an electric motor or otherwise. MHD does not have a electric motor per-say. It uses MHD properties of salty water to propel the sub.

And yes MHD drive is a pipe-dream. Jet-Pumps are not. Jet-Pumps are used a lot in lifting water from bore-well in everyday life.

Hope that clarifies.
There are moving parts with the Vanguard and Astute systems but the drive does not involve mechanical contact with the prop and there is no cooling pump for the reactor, so there is no noise aside from that of the prop on the water.
 
There are moving parts with the Vanguard and Astute systems but the drive does not involve mechanical contact with the prop and there is no cooling pump for the reactor, so there is no noise aside from that of the prop on the water.

That's probably because you don't have technology for cooling pump. Or maybe the leak in the drive pushes water in at the rate of 200L/Hr and no cooling pump will be needed......
 
There are moving parts with the Vanguard and Astute systems but the drive does not involve mechanical contact with the prop and there is no cooling pump for the reactor, so there is no noise aside from that of the prop on the water.
I will not comment on Coolant Pump part as this discussion is primarily related to propulsion.

For Jet Pump, there is no propeller to say, but there is indeed a mechanical impeller which pushes the water out at a higher pressure and kinetic energy. This jet of water then pushes the vessel ahead. So yes, there will be a mechanical contact between impeller and the water and just like propeller, a fast rotating impeller can cause cavitation which, in turn can cause a loud 'pop' when the bubbles burst and -- heck -- can cause mighty damage to the impeller and the pump. This is something which is not just limited to submarine propulsion but also else where in day to day life. A jet pump design which does not involve mechanical contact with water is unusual and I am not aware of such design. Do you have a source for such?

@vstol Jockey : You were once in navy. Have you heard of any pump-jet without mechanical contact with water?
 
I will not comment on Coolant Pump part as this discussion is primarily related to propulsion.

For Jet Pump, there is no propeller to say, but there is indeed a mechanical impeller which pushes the water out at a higher pressure and kinetic energy. This jet of water then pushes the vessel ahead. So yes, there will be a mechanical contact between impeller and the water and just like propeller, a fast rotating impeller can cause cavitation which, in turn can cause a loud 'pop' when the bubbles burst and -- heck -- can cause mighty damage to the impeller and the pump. This is something which is not just limited to submarine propulsion but also else where in day to day life. A jet pump design which does not involve mechanical contact with water is unusual and I am not aware of such design. Do you have a source for such?

@vstol Jockey : You were once in navy. Have you heard of any pump-jet without mechanical contact with water?
Yes, there is a shrouded mechanical contact with the water but, there is no mechanical contact between the propeller and a driveshaft.
 
That's probably because you don't have technology for cooling pump. Or maybe the leak in the drive pushes water in at the rate of 200L/Hr and no cooling pump will be needed......
No, it's because pumps make noise.

And yes *yawn*, we've all heard about the small, blown-out-of-all-proportion seal leak on the QE of ~50ml/s, which is slower than most people drink. It is common to find these during sea trials and hence one of the reasons why sea trials are done. I suspect the subs leak much faster than that, otherwise they wouldn't be submarines.;)