055 DDG Large Destroyer Thread

[Blitzo]

You are making things up now. Look at the Type 003 under construction and how far away the MERs are spaced. That is with the intent purpose for the ship to weather blast/flooding damage in that compartment and at the very least keep on steaming if not fighting. A ship dead in the water is a major liability. If the threat environment is unfavorable, they typically end up scuttled by their own side.

Even the Type 055 has a compartment of separation between its MERs. That's evidence that they do care about battle damage.
Smokestack separation correlates with MER separation. Sometimes, if volume is available, additional ducting can be used to increase separation. Based on diagrams published by CCTV, they don't seem to have increased the separation by much if at all compared to the smokestacks:
View attachment 70197

View attachment 70196

Okay, so first of all, your original argument should never have been about the funnels to begin with, but the prime movers or MERs.
I'm not sure why you were so focused on the funnels in post #419, when the actual point of your argument is about the position of the prime movers. Why bother using the funnels as a proxy.

As for the positioning of the prime movers themselves, it's not quite so simple as you describe.

The ideal ship to maximize survivability of its prime movers and immediate adjacent gear boxes would ideally have them spaced far away from each other, duplicating redundancy as well.
But that adds complexity, weight, and is limited by the geometry of your ship.
It also limits the kind of gearing that your ship can accommodate.


In the case of 055, it is basically confirmed that it adopts a combined connector gear COGAG system, which basically allows one single gas turbine to run at full efficiency to propel both shafts -- or up to all four to propel both shafts.

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Compare that to say, the Spruance/Tico (depicted below) or Burke family, where each shaft is only connected to two of each of the four gas turbines. Not as big of a problem if you're running all four turbines at full speed, but it becomes an issue if you want to cruise more economically, meaning you are forced to run a single gas turbine to turn a single shaft, while the other shaft is actually left unpowered to just turn in the current.






And then of course there are a whole heap of weird and wonderful arrangements of prime movers and gear boxes and shafts depending on type:





And one can find quite a few good 3D depictions of their setups in certain promotional material, such as here, including for various naval ships like F125, FREMM, NSC:

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..... All this is to say, it isn't quite a simple as "bad design because prime movers all located close together" -- but it was likely a deliberate and informed choice to balance the requirements of survivability and the output, efficiency and reliability of their propulsion configuration, as well as in relation to the overall kind of damage they assess to be likely, and the other tradeoffs in terms of placement of weapons, sensors etc.

E.g. if we were only to consider the propulsion configuration alone: if the PLAN had chosen to space out the prime movers of 055 in a manner similar to Spruance/Tico class, would they have been able to install a combined connector gear system? What is their assessment of likely damage to the propulsion system -- e.g.: flooding versus direct damage to the prime movers versus breaking of the shaft? Would spacing of the prime movers been able to enable them to put in six auxiliary generators for service power in the way they did on the 055? etc

I don't think we have the ability to divine the answers to those questions to reach a sensible conclusion.


If you wanted to have a discussion about comparative design trade offs for various propulsion configurations and to evaluate 055's configuration, I don't think anyone would have had an issue with that.
But the way you wrote post #419 is oversimplistic and overreaches.

 

[Tyler]

An antiship missile will likely head where its return signal is at the strongest, and that's the part of the ship where it has the highest radar cross section. Clue, that isn't where the funnel is. Second clue, that's close to where the ECM is placed at. Third, that's why the ECM is placed there in the first place.

They will probably place the funnels apart more in the type 55A.

 

[ougoah]

Harpoon is just one missile PLAN should be worried about. SM-2 and SM-6 will hit the ship from a plunging trajectory. NSM can be programmed to hit any desired point on the ship, including the smokestacks if that's desired. Probably the same for the LRASM and the upcoming JSM. And that's just the US threat.

You are making things up now. Look at the Type 003 under construction and how far away the MERs are spaced. That is with the intent purpose for the ship to weather blast/flooding damage in that compartment and at the very least keep on steaming if not fighting. A ship dead in the water is a major liability. If the threat environment is unfavorable, they typically end up scuttled by their own side.

Even the Type 055 has a compartment of separation between its MERs. That's evidence that they do care about battle damage.
Smokestack separation correlates with MER separation. Sometimes, if volume is available, additional ducting can be used to increase separation. Based on diagrams published by CCTV, they don't seem to have increased the separation by much if at all compared to the smokestacks:
View attachment 70197

View attachment 70196

A torpedo hit in the middle compartment where the clutches and reduction gear(?) appear to be located stands a good chance to cripple the main propulsion.

They don't, as I've pointed out above.

I beg your pardon. What did you say your credentials were?

Please stop embarrassing yourself for your own sake. Show me any instance in shipbuilding and design where smokestack positioning is a matter of vital importance and they must be spaced as far as possible because AShM target them and are programmed to target them. Tico class happens to have them separated further. Many don't.

SM series can be used as anti-ship as a secondary role like many SAMs. They are just very unlikely to be used in such a way because they are the least effective means of anti-shipping for the USN. Why should they design the Type 055 with the most unlikely situation in mind?? You make no sense at all like a classic Jai Hind troll.

Have you forgotten all the sensors, helicopter, and VSL that are on the 055?? Where should they position those just so they can please you with a well separated smokestack?

If a ship's smokestack can be hit, that ship is close to useless because it can be hit with a lot more and in many more important places. The smokestack is literally the most unimportant part of a ship. On MERs the 055 has separation like you said because it is able to provide that much with all things considered. It needs to fit over 100 large VLS as well. That's its primary purpose, surviving strikes a secondary one. The whole point is to avoid being struck and to strike the opponent first, in case you have forgotten. Maybe this is what the wesuck class does better when it finally gets things glued together. Now that's a "stels" ship if we've ever seen one.



Type 003 is a carrier. It has the space to accommodate greater separation of MERs.

If a captain simply had to take a hit somewhere, they would probably choose it to be the smokestack lol. Name one other area that is less important.

You realise the purpose of the ship is to not get hit by anything right? It's to put to as great use as possible all its sensors and missiles. Everything is secondary to that. It defends itself using sophisticated sensors and missiles so that it doesn't take a single hit. It doesn't defend itself using designs that take into consideration being hit. That comes after all the sensors and weapons are considered and designed for. Ergo, any "survivability" design comes second to having ideal firepower and firepower support in place. Where the smokestacks are positioned on the 055 came as a decision AFTER the helicopter station and VLS and sensors are set in ideal positions. THEN they considered the propulsion units and smokestack.

 

[ougoah]

NSM is a minor minimal threat and very low presence in USN. The major threats need to be addressed before minor near non-existant threats. Major threat = F-35, SSN, drones, air launched stealthy stand off ordinance. NSM is a nil threat in the hands of other navies because those nations don't want to be shooting at a 055 for no reason. Malaysia would sooner be shooting NSM at an Indian tugboat than it would be at a Chinese Type 055. USN NSM is a lower presence threat compared to carrier fighters.

The US possess much superior anti-shipping weapons than NSM. PLAN would much rather counter SSN and F-35 than would care to counter yet another type of stealthy anti-ship cruise missile which onboard interceptors and sensors are equipped to deal with along with fighters and assorted threats. We're in the age of hypersonic glide weapons, anti ship ballistic missiles with MaRV, and underwater drones. If NSM style weapons were so effective at sinking major surface vessels of superpowers, China, Russia, and the US would have several types. BTW the frontal aspect RCS of a sea-skimming YJ-12 or YJ-18 is nominally not much more than an NSM. Perhaps that explains why neither Russia or China bother with more sea-skimming cruise missiles and prefer HGVs and AShBMs to carry the high end threat.

 

[nlalyst]

Okay, so first of all, your original argument should never have been about the funnels to begin with, but the prime movers or MERs.
I'm not sure why you were so focused on the funnels in post #419, when the actual point of your argument is about the position of the prime movers. Why bother using the funnels as a proxy.

My concern was really about the funnel spacing in my initial post. It was only after @ougoah insisted that missiles don't aim at smokestacks that I pointed out that funnel spacing is a proxy for MER spacing. I find it very difficult to discuss the original question when all the follow up arguments were essentially that it's a pointless concern because missiles don't aim at smoke stacks. Sorry, but I would really like to settle the funnel question first.

As for the positioning of the prime movers themselves, it's not quite so simple as you describe.

The ideal ship to maximize survivability of its prime movers and immediate adjacent gear boxes would ideally have them spaced far away from each other, duplicating redundancy as well.
But that adds complexity, weight, and is limited by the geometry of your ship.
It also limits the kind of gearing that your ship can accommodate.

So you agree that larger separation of prime movers in general means better survivability? How about the smoke stacks? Does it matter or not?

In the case of 055, it is basically confirmed that it adopts a combined connector gear COGAG system, which basically allows one single gas turbine to run at full efficiency to propel both shafts -- or up to all four to propel both shafts.
View attachment 70199

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If true, and the CCGs are the equipment in the in-between MERs compartment as shown in the CCTV illustrations, doesn't that make damage to that compartment potentially catastrophic as all 4 prime movers are tightly coupled there?

..... All this is to say, it isn't quite a simple as "bad design because prime movers all located close together" -- but it was likely a deliberate and informed choice to balance the requirements of survivability and the output, efficiency and reliability of their propulsion configuration, as well as in relation to the overall kind of damage they assess to be likely, and the other tradeoffs in terms of placement of weapons, sensors etc.

Yes, of course, there are design trade-offs. But that wasn't my concern/question. I pointed out that for its size, the Type 055 has main engine funnels unusually close to each other. I enumerated and measured 6 other combatants to demonstrate my point.

If I can rephrase: is the small spacing of funnels a liability or not when hit in that location? If it is, than it's a weak point. There could be other weak points (like the CCG compartment), I am not denying that. It might make more sense to aim at those other weak points. I am not denying that either. But one item at a time, please.

 

[nlalyst]

NSM is a minor minimal threat and very low presence in USN. The major threats need to be addressed before minor near non-existant threats. Major threat = F-35.

The main anti-ship weapon of the F-35 will be the JSM, a missile derived from the NSM. So by your own admission, NSM like weapons are a major threat. Over 150nm range in a 400kg missile with a 125kg warhead.

SImilar to the NSM/JSM, LRASM too uses optical guidance and has been in service since 2018. Counter action against LRASM should also work against the NSM/JSM and I have no doubt PLAN is taking the threat very seriously.

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But please let's first settle the funnel question, before shifting the discussion towards ASBMs and hypersonic glide warheads and various other weapons and platforms.

 

[ougoah]

The main anti-ship weapon of the F-35 will be the JSM, a missile derived from the NSM. So by your own admission, NSM like weapons are a major threat. Over 150nm range in a 400kg missile with a 125kg warhead.

SImilar to the NSM/JSM, LRASM too uses optical guidance and has been in service since 2018. Counter action against LRASM should also work against the NSM/JSM and I have no doubt PLAN is taking the threat very seriously.

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But please let's first settle the funnel question, before shifting the discussion towards ASBMs and hypersonic glide warheads and various other weapons and platforms.

The main threat there is the F-35. Countering the threat of JSM from F-35 is different to countering the threat of NSM launched from a ship or land. The NSM is a ship or land based missile. You quoted NSM. I addressed the former threat type as F-35. Did you suppose I meant F-35 used as a kamikaze vehicle? Of course not. The implication was the weapons package available to the F-35. So no, the NSM is still a nil threat in Malaysian hands and a much smaller threat in USN compared to F-35, SSN, HGVs (which the Americans are testing) and most importantly, the carriers that support the F-35s

What is your funnel question? That the smokestakes on the 055 are too closely spaced? If that's the question/concern, I will set your mind at ease. The designers of the 055 put capability in front of giving MERs huge separation. In order to achieve high VLS and overall offensive capability, the designers were left with less room for choice when it came to spacing the smokestakes. I suppose the Chinese just want superior sensor and firepower over a well separated smokestake and MERs.

Is this really a topic worth picking? Is that really a question worth asking? Do you realise how packed the ship is?

 

[Tam]

Not if the missile uses optical guidance, like the NSM.

Old trick, that's been seen a long time ago. Ever since the first pair of Type 052B, the funnel has a reduced thermal signature. China also experimented with funnel less designs with the heat emanated directly behind the water, in the Type 022 and the Algerian C28 corvette. Most warships nowadays since the beginning of the 'stealth' era of modern warship design, feature reduced IR funnels. The 055 seems to take it to a new level; the actual funnels themselves are small relative to all the structure around it that is filled with vents and quite possibly, fans designed to vent the air in and cool the entire structure.

Optical guidance is a last ditch resort against radar jamming but by itself, its not something to be selected as the primary guidance system for many reasons. One is that its range is considerably short, often lessened by weather, clouds, fog and so on. It can be blinded by the sun, fooled by flares, blocked by chaff and smoke.

 

[nlalyst]

Optical guidance is a last ditch resort against radar jamming but by itself, its not something to be selected as the primary guidance system for many reasons. One is that its range is considerably short, often lessened by weather, clouds, fog and so on. It can be blinded by the sun, fooled by flares, blocked by chaff and smoke.

Last ditch resort? NSM does not even have a radar. It uses a combination of inertial, GPS and optical guidance. LRASM has all the guidance features of the NSM and adds a passive RF detector.

If optics are a last ditch resort, how do you explain then the fact that two of the newest anti-ship missiles in the US arsenal don't have active radar guidance?

 

[nlalyst]

Why would a ships propulsion stop if the smokestacks were destroyed...

The degradation would depend on the amount of damage inflicted. Less air into the engines => less performance. Gas turbines are more vulnerable as they require a lot of air and don't handle debris injection very well. An explosion in the funnel has a good chance of taking out the gas turbines.