Chinese submarines thread

[Violet Oboe]

Re: Chinese sub thread

If your assumptions about 091 mod types and three 093/093A types actually existing would prove correct dear Crobato and Roger; I would be left wondering:
Were the recent editions of the DoD report about China's military intended as an exercise in disseminating disinformation, just crappy bullshit produced by a hapless DoD intern or are there indeed some ´knowledge gaps´ better kept under wraps and shielded from potential criticism from Congress?

What do you think Crobato, Roger ...?

 

[tphuang]

Re: Chinese sub thread

I think you got me confused with Fishhead. Looking at the link again, lo and behold, they changed it! This is what the paged used to say:

you didn't post any link

Alas, you're saying we can't be sure of anything

I'm just speculating based on incomplete information:

- we know that PLAN requirement is nuclear subs comparable in noise level to Seawolf/Virginia and Ohio (~110 dB)

- we know they'll keep making interim designs until they get to that point, and then serial produce

- they've been doing sea trials on the second Type 093 and the first Type 094 since 2004

- they may have gone public with the Type 093 for the first time because they started serial production, or because they have a new 2007 interim design to play with (it's been 3 years since 2004, so it's about time)

- rumors about difficulties with the Type 093 program suggest the latter

huh? There is not a chance that you can get to Seawolf/Virginia level acoustic signature with 093. These figures are all taken from Internet warrior speculations in the recent years. Let's put it this way, even in the conventional sub area, they only got something comparable to Kilo in acoustic signature, how would they do something an order better with a nuclear sub. If I was to venture a guess, it would probably be between Victor III and Early Akula, which would be already a huge jump from 091.

 

[Totoro]

Re: Chinese sub thread

One has to take into account that larger diameter subs usually mean quieter subs, for the same tech level. Thing is, all the quieting of US subs in the past few decades hasn't come by by some wizard like super high tech solutions - most of if came by very, very delicated thought out conventional engineering. Key is to detach anything that produces sound from the submarine itself - and put it on harnesses, various shock absorbers, etc. To minimize vibrations as much as possible. And all that insulation requires primarely space. That is not to say that design principle of coolant pumps or design of the propeller itself doesn't influence the overall noise levels a lot - of course it does. But every little piece of the puzzle must work perfectly in order to get the desired result. Sturgeon class, US first quiet sub, was to be very quiet on paper, only to be discovered that first one produced was rather noisy. Why? Cause the builders didn't pay enough attention to precision of their work. An extra decibel of sound got added here, extra two there, and in the end it was rather different than the design called for. Subsequent subs got much quieter after additional, very strict quality control was integrated into the building process.

 

[fishhead]

Re: Chinese sub thread

Actually, Chinese site doesn't say anything except quoting Janes speculation about 093, including that speed, and they explicitly says they're not responsible for any data's accuracy. So there is no ground to discuss it.

The photo was taken from big screen TV, just tell you it's 093. The angle of the picture was arranged in the way of facing the light, not much detail you can see. Everything seems to be carefully Orchestred.

 

[Roger604]

Re: Chinese sub thread

First series of 093 built with diving planes in conning tower. Probably two.

Second series of 93 built without diving planes in conning tower. One or two.

In 2004, first 94 launched based on second series of 93.

This is rather sketchy, but at least for now, there is some light being shed in one of the most hidden of the PLA programs.

I have a hypothesis that could explain why Type 093 is not satisfactory while Type 094 is satisfactory enough for serial production:

After Type 093's were launched, PLAN made a breakthrough in pump jet technology that allowed it to be used on the next design. The Type 093 design was already maturing, since it had already been modified once (the diving plane-less sails). It would be completely impractical to try to modify the existing design to use a pump jet instead of a 7 blade screw.

So the decision was made to build the Type 094 with a pump jet. But now the Type 093's are made obsolescent, and an entirely new design is needed for an attack submarine. That's why the modified Type 093's can have an array of quieting technologies, the same as those on the Type 094, yet was still not satisfactory -- the fundamental design was made obsolescent, even if the bells and whistles were not.

Notice the model in front of Huang Xuhua:

Aren't acoustic tiles meant to 'combat' active sonar (mainly high frequencies) and not passive one?

According to this article, it's both active sonar and internal noise (but obviously not hydrodynamic noise or noise from the propulsion).

Please, Log in or Register to view URLs content!

Does seawolf then posess both the pump jets and a screw? So, where exactly on the hull are the openings for the pump jets located? Or is it possible that seawolf doesn't have a screw under that protective ring?

Wouldn't the opening (nozzles?) always be behind the sub? It should be the same as any other sub with pump jet propulsion. They just don't have an exposed screw.

Were the recent editions of the DoD report about China's military intended as an exercise in disseminating disinformation, just crappy bullshit produced by a hapless DoD intern or are there indeed some ´knowledge gaps´ better kept under wraps and shielded from potential criticism from Congress?

There is a classified version, and I'm sure Congress gets that one. The public version seems conservative when discussing capabilities. An official government publication (usually) can't go about making conjectures like some Chinese military forumites!

you didn't post any link

There's obviously a misunderstanding. You said, "that link you posted contains nothing about the 50 knots and such (that I can see)." I assume you were talking to me, but referring to the link posted by Fishhead (along with the photos). And on that linked web page, the claims about 50 knots were there and then removed.

huh? There is not a chance that you can get to Seawolf/Virginia level acoustic signature with 093. These figures are all taken from Internet warrior speculations in the recent years. Let's put it this way, even in the conventional sub area, they only got something comparable to Kilo in acoustic signature, how would they do something an order better with a nuclear sub. If I was to venture a guess, it would probably be between Victor III and Early Akula, which would be already a huge jump from 091.

Fair enough. The main point is... if we see Type 094 as not so much a parallel project with Type 093, but as its successor in terms of technology level, then it neatly explains why Type 093 is not satisfactory enough for serial production while Type 094 is. This is consistent with reports that Type 093 has been around since late 90's while the first Type 094 was launched in 2004.

In the 6 years or so since the last Type 093 was built, it's quite possible that Chinese submarine technology experienced breakthroughs that brought designs from an Akula level down to somewhere between a Seawolf and a 688I level (~110 dB). Look at where Chinese surface ships were in 2001 compared to Type 054A.

Just a quick point about SSK's. Isn't a Kilo, if fitted with AIP, pretty much the pinnacle of SSK technology? That's more or less what Lada/Amur is, as far as I know.

 

[bd popeye]

Re: Chinese sub thread

A New Type of Sub in the China navy! Tensions in the pacific are grtting hotter, and between China and Tiwan indeed.Besides North Korean nukes a Third World War might com in the future. If it does i'm on Chinas side. I wounder how the U.S.A will handdel this new sub:china:

To build them is one thing. To operate them is another. When the PLAN is able to put to sea it's sub force in numbers with highly trained crews that are professional, proficent and "salty". Then and only then will they be a viable sub force.

Salty= A sailor who has years of experience of actual at sea time.

 

[elinge]

Re: Chinese sub thread

I believe that the chinese knows that's it's not necessary to build and operate under the sea a great number of "soffisticate" SSBN for beeing considereded a viable "sub deterrent force" . Only two SSBN with capacity of launch nuclear weapons are, from my point of view, the only strategic weapons that China wish to adquire, while assign "big" funds and efforts to build and reinforce it's "great weapon": it's formidable and solid economic and financial and work capacity for beeing one alternative "leader country" in the present century.
Now the world knows that China has one SSBN who added strategic and attack nuclear capacity to "Chinese arsenal".....and this is aligned with China's strategic global project.

 

[RedMercury]

Re: Chinese sub thread

10 dB difference is 10 times louder.

 

[tphuang]

Re: Chinese sub thread

I have a hypothesis that could explain why Type 093 is not satisfactory while Type 094 is satisfactory enough for serial production:

After Type 093's were launched, PLAN made a breakthrough in pump jet technology that allowed it to be used on the next design. The Type 093 design was already maturing, since it had already been modified once (the diving plane-less sails). It would be completely impractical to try to modify the existing design to use a pump jet instead of a 7 blade screw.

So the decision was made to build the Type 094 with a pump jet. But now the Type 093's are made obsolescent, and an entirely new design is needed for an attack submarine. That's why the modified Type 093's can have an array of quieting technologies, the same as those on the Type 094, yet was still not satisfactory -- the fundamental design was made obsolescent, even if the bells and whistles were not.

Notice the model in front of Huang Xuhua:
[qimg]http://mil.eastday.com/eastday/mil/node62186/node62671/node62673/node135714/images/00667539.jpg[/qimg]



According to this article, it's both active sonar and internal noise (but obviously not hydrodynamic noise or noise from the propulsion).

Please, Log in or Register to view URLs content!

Wouldn't the opening (nozzles?) always be behind the sub? It should be the same as any other sub with pump jet propulsion. They just don't have an exposed screw.



There is a classified version, and I'm sure Congress gets that one. The public version seems conservative when discussing capabilities. An official government publication (usually) can't go about making conjectures like some Chinese military forumites!



There's obviously a misunderstanding. You said, "that link you posted contains nothing about the 50 knots and such (that I can see)." I assume you were talking to me, but referring to the link posted by Fishhead (along with the photos). And on that linked web page, the claims about 50 knots were there and then removed.



Fair enough. The main point is... if we see Type 094 as not so much a parallel project with Type 093, but as its successor in terms of technology level, then it neatly explains why Type 093 is not satisfactory enough for serial production while Type 094 is. This is consistent with reports that Type 093 has been around since late 90's while the first Type 094 was launched in 2004.

In the 6 years or so since the last Type 093 was built, it's quite possible that Chinese submarine technology experienced breakthroughs that brought designs from an Akula level down to somewhere between a Seawolf and a 688I level (~110 dB). Look at where Chinese surface ships were in 2001 compared to Type 054A.

Just a quick point about SSK's. Isn't a Kilo, if fitted with AIP, pretty much the pinnacle of SSK technology? That's more or less what Lada/Amur is, as far as I know.

we will know whether pump jet is on 093/094 when we see the next conventional sub coming out. If that one has pump jet, then we can venture to guess that the more important nuclear subs will get the latest technology. Remember, when it comes to pump jet, there are also many different degrees. Even though we've seen pump jet with the Russians, it's safe to say that it's far behind that of the Western countries who have been using pump jet propulsions for much longer.

As for comparing 093 to 054A, I don't see 054A as the most advanced frigate in the world, but rather the first advanced design that China has had. Same with 093, if it can achieve let's say early Akula level acoustic signature, I think that would already be a huge jump. As for Kilo, it's no where near the pinnacle of SSK technology, it's still probably an order or more noisier than Amur, which is still noisier than leading conventional subs like Oyashio and Collins.

 

[szbd]

Re: Chinese sub thread

OK, we need some physics here. The amplitude of sound is defined as

20x[log(S/S0)]

where S is the sound to be measured and S0 is a standard sound. The base of log here is 10. Actually the S and S0 is measured as pressure. So if two sounds S1 and S2 has 10 db difference, that means

20x[log(S1/S0)]-20x[log(S2/S0)]=10

equivalent to

log(S1)-log(S2)=0.5

so

S1=S2x10^0.5=3.162xS2