055 DDG Large Destroyer Thread

[Solaris]

I'm not very knowledgeable such matters either, but what of the ticonderogas? Their air intakes seem to be right alongside its smoke stacks, not particularly forward or rear. But then again maybe I'm looking at the ship wrong.

I suppose they could be parallel to the stacks, but the forward intakes shouldn't be rearward of the forward stacks, and the rear intakes shouldn't be forward of the rear stacks.

I wouldn't say the air intakes are particularly in danger of taking in VLS exhaust, at least compared to other ships in terms of the location of the intakes on the vessel relative to the VLS. The ship would constantly steam forwards I imagine, during combat, so the rest of the hull aft of the forward VLS will move "under" the exhaust of fired missiles. burkes, ticos, and virtually any other normally designed surface combatant has air intakes positioned amidships around the centreline that will cross under any forward VLS exhaust. And I don't think the side facing air intakes of those ships versus upward facing intake of the CGI 055s will show major differences in amount of potential exhaust sucked in.

I don't think HQ-10 makes that much exhaust when firing either, and from its positioning, it is very much aft of the air intakes so I doubt they will suck in what little smoke is there. But then again I've never stood next to an air intake on a DDG during operation so maybe I'm wrong.

Neither the Ticonderogas or the Arleigh Burkes have intakes anywhere near potential VLS exhaust. By the time forward VLS exhaust makes its way towards the rear of the ship the smoke would long have been mostly or totally dissipated by the deckhouse and other intervening structures. If that 055 retains the same structure with only the air intakes moved around, there is certainly danger of either or both VLS and HQ-10 exhaust being drawn into the rear GT's. Especially if the HQ-10 launcher's backside is pointed directly at an air intake during the course of slewing and firing against an incoming target, you could get a giant blast of exhaust going straight into the intake. As for the VLS, even with a ship traveling at speed, the initial exhaust from a launch will travel in all directions until the missile is well above the ship, before the exhaust starts drifting rearward. During these launches you will get an opportunity to contaminate the air going into the rear intake.

I'm also not sure if the air intakes opening face is on a poor axis. I imagine there must be other ships where they face upwards rather than sideways. Would the only danger be rainwater?

I've never seen a ship's air intakes facing straight up towards the sky, for reasons which I feel are pretty obvious: while I have no doubt there is probably some kind of mechanism to trap/divert up to a certain amount of water in a catch basin prior to the air entering a GT, as well as the GT itself being able to tolerate some amount of moisture in the air, you would likely overwhelm such a mechanism with a nicely timed wave washing over the deck of a ship assisted by gravity, that you wouldn't experience nearly as much with a vertically-facing air intake.

 

[Blitzo]

I suppose they could be parallel to the stacks, but the forward intakes shouldn't be rearward of the forward stacks, and the rear intakes shouldn't be forward of the rear stacks.

Hmm is there anything stopping the air intake pipes from branching to the GT the same way the GT's exhaust pipes branches up to the smoke stack like on burkes?

Neither the Ticonderogas or the Arleigh Burkes have intakes anywhere near potential VLS exhaust. By the time forward VLS exhaust makes its way towards the rear of the ship the smoke would long have been mostly or totally dissipated by the deckhouse and other intervening structures. If that 055 retains the same structure with only the air intakes moved around, there is certainly danger of either or both VLS and HQ-10 exhaust being drawn into the rear GT's. Especially if the HQ-10 launcher's backside is pointed directly at an air intake during the course of slewing and firing against an incoming target, you could get a giant blast of exhaust going straight into the intake. As for the VLS, even with a ship traveling at speed, the initial exhaust from a launch will travel in all directions until the missile is well above the ship, before the exhaust starts drifting rearward. During these launches you will get an opportunity to contaminate the air going into the rear intake.

I think in there isn't a great difference in length between the notional 055s air intakes and it's forward VLS compared with that of the VLS-to-forward air intake distance for burke and ticonderoga. They will all pass under potential exhaust routes of the forward VLS, with similar degrees of obstruction by the forward superstructure, I think.

I've never seen a ship's air intakes facing straight up towards the sky, for reasons which I feel are pretty obvious: while I have no doubt there is probably some kind of mechanism to trap/divert up to a certain amount of water in a catch basin prior to the air entering a GT, as well as the GT itself being able to tolerate some amount of moisture in the air, you would likely overwhelm such a mechanism with a nicely timed wave washing over the deck of a ship assisted by gravity, that you wouldn't experience nearly as much with a vertically-facing air intake.

Yep, you'll see no major arguments from me on this particular point. I wonder if zumwalt has it air intakes on the top of its superstructure, however. It certainly doesn't look like they are on the sides...


Anyway, this is all academic, and chances are the air intakes will be placed with more logic than the CGIs. Maybe if we are lucky the PLAN would have gone a more low visibility route and make the air intakes hard a hell to spot like on zumwalt or type 45

 

[Solaris]

Hmm is there anything stopping the air intake pipes from branching to the GT the same way the GT's exhaust pipes branches up to the smoke stack like on burkes?

You mean 'angles up' to the stacks? Or something else?

What I'm trying to get at is that it would seem illogical and wasteful for the ducting system of a GT to be arranged so that the exhaust ducting and intake ducting cross each other on the way up/down. That would result in a lot of angled ducting and space wasting.

I think in there isn't a great difference in length between the notional 055s air intakes and it's forward VLS compared with that of the VLS-to-forward air intake distance for burke and ticonderoga. They will all pass under potential exhaust routes of the forward VLS, with similar degrees of obstruction by the forward superstructure, I think.

As I have been saying, I have not been concerned with the exhaust from the forward VLS on either of the USN ships or the notional 055 design. By the time the forward VLS exhaust washes over the side of the ship, it will already have been deflected in many different directions by the presence of the deckhouse and therefore significantly diminished by the time any of it reaches the side-facing intakes, possibly to the point of non-existence. It is the exhaust from the HQ-10 and the rear VLS that IMO would be situated too close to a (correctly) placed rear air intake. There are no intervening structures to deflect the exhaust, and during the missile's initial assent out of its tube the exhaust will be flying everywhere, including (forward) into the rear air intakes. The rear intakes on the Arleigh Burkes (the ones that sit directly underneath the SPG-62 directors) are located significantly farther away from the rear VLS than the intakes on the 055 and its rear VLS.

 

[Blitzo]

You mean 'angles up' to the stacks? Or something else?

What I'm trying to get at is that it would seem illogical and wasteful for the ducting system of a GT to be arranged so that the exhaust ducting and intake ducting cross each other on the way up/down. That would result in a lot of angled ducting and space wasting.

Hmm angling might be worth the external superstructure arrangement being more stealthy. Also, I'm not quite sure how space efficient the various air intakes for other ships compare so I don't think we can judge the notional 055 (or the future 055) for being space inefficient without having an average to compare with.

As I have been saying, I have not been concerned with the exhaust from the forward VLS on either of the USN ships or the notional 055 design. By the time the forward VLS exhaust washes over the side of the ship, it will already have been deflected in many different directions by the presence of the deckhouse and therefore significantly diminished by the time any of it reaches the side-facing intakes, possibly to the point of non-existence. It is the exhaust from the HQ-10 and the rear VLS that IMO would be situated too close to a (correctly) placed rear air intake. There are no intervening structures to deflect the exhaust, and during the missile's initial assent out of its tube the exhaust will be flying everywhere, including (forward) into the rear air intakes. The rear intakes on the Arleigh Burkes (the ones that sit directly underneath the SPG-62 directors) are located significantly farther away from the rear VLS than the intakes on the 055 and its rear VLS.

Oh my bad, I thought we were talking about the forward VLS on the notional 055.

In that case, I think there are many ways they can design the air intakes to avoid the rear VLS exhaust. Simply make it like the notional 055 design (maybe arrange it on the flanks of the ship's hull ala the burke's most forward placed air intakes, if upward facing air intakes aren't practical), or maybe arrange the air intakes on the main smoke stack instead with the four GTs arranged not in pairs but in a line of four, allowing more space in the smoke stack to have both the air intake and the exhaust. Maybe they'll surprise us and show a super stealthy and low profile air intake design that is less dependent on a single large intake.
There are an almost infinite ways for them to avoid the problem of rear VLS exhaust based on the ship's known smoke stack structure, I think.
Basically, if an air intake is in danger of sucking in a dangerous amounts of VLS exhaust, then chances are it won't be placed there, and they will instead put it somewhere else, which may possibly be a little less space inefficient yes, but which confers to the outward structural specs and is not in danger of taking in missile smoke.

I think it is a tad early to consider where the intakes are, IMO. Chances are we will only see it when the ship is launched.
But what we do know is they'll choose a placement that works. Based on what little we know about the ship's structure, they have a good bunch of potential positions to choose from.

 

[Totoro]

we don't even know if there is going to be ciws on the sides, and even if there are, we don't know which kind nor their exact position.

I would imagine 055 might have the following turbine arrangement: (gb - gearbox, dots represent empy space )

prop shaft<--g
....................b <--turbine3--<intake
turbine1-- > 1

turbine2---> g
...................b <--turbine4--<intake
prop shaft<--2

while it's also possible that gearbox for turbines 1 and 3 is behind turbine 1, and then turbine 1 (And 2) is orientated differently, so its intake is between turbine 3 and 1 (offset a bit of course), i don't know if such arrangement is good for future electric propulsion variant. One would expect, if they do plan to switch to IEP with the next variant, they would already use the overall layout that's best for future modifications.

With the layout as shown above, intakes of 3 and 4 would be in front of their exhaust, possibly far to the side of the ship's hull. intakes of 1 and 2 would then probably be at the extreme end of the engine superstructure, on the sides. Or maybe even not on the sides but looking straight back, if the VLS was found not to interfere with it.

As for tico, i can't for the life of me find a schematic of its propulsion, but it would appear that it has intakes either parallel to each par of exhausts of even in the case of rear exhaust pair the intakes might actually be right aft of the exhausts. I am speculating that ticos may actually have the following arrangement:


.................................g<--turbine3
prop<-----------------b
...........turbine1-->g...2<--turbine4
prop <-------------b
...........turbine2-->1

 

[Solaris]

we don't even know if there is going to be ciws on the sides, and even if there are, we don't know which kind nor their exact position.

Right, what I'm saying is that I think a pair of flank-mounted HQ-10 launchers at that location would be a bad idea, unless the design is changed somewhat so that they are placed further away from the rear intakes.

I would imagine 055 might have the following turbine arrangement: (gb - gearbox, dots represent empy space )

prop shaft<--G
...................B <--turbine3--<intake
turbine1-- > X

turbine2---> g
...................b <--turbine4--<intake
prop shaft<--2

Or like this (the font mechanism for this site is so stupid):


.......................Stack...............Stack
................Intake...|...................|...Intake
.................\|/..../|\................./|\....\|/
..................|......|...................|.....|
.................[TURBINE3]->[R]->|G|<-[R]<-[TURBINE1]
X<-----------prop shaft<----------|B|

X<-----------prop shaft<----------|G|
.................[TURBINE4]->[R]->|B|<-[R]<-[TURBINE2]
..................|......|...................|.....|
................./|\....\|/.................\|/..../|\
................Intake...|...................|...Intake
.......................Stack...............Stack

Where [R] is the reduction gearbox for each GT and |GB| is the combined gearbox for the prop shafts.

With the layout as shown above, intakes of 3 and 4 would be in front of their exhaust, possibly far to the side of the ship's hull. intakes of 1 and 2 would then probably be at the extreme end of the engine superstructure, on the sides. Or maybe even not on the sides but looking straight back, if the VLS was found not to interfere with it.

Probably side-facing at the rear of that large structure would be my guess, so as to not be facing the rear VLS.

 

[Solaris]

Interestingly, doing some internet research, this seems to be KDX-II's COGAG arrangement:


.................[TURBINE4]->[G]
X<-----------prop shaft<-----|B|
.................[TURBINE3]->|X|
..................................|G|<-[TURBINE2]
X<-----------prop shaft<----------|B|
..................................|X|<-[TURBINE1]


I could easily imagine the Burke and similar ships like the Kongou and Atago using this arrangement as well.

Edit: check out this jewel of an article advocating HED (hybrid-electric drives) for the ABIII's and other future ships. There is what I think is a money shot (re: Burke's GT arrangements) at the middle of the page:

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The article also contains some juicy bits about carrier battle group formations, like the "plane guard" cruiser/destroyer position astern of the carrier, etc.

I think the current production Burkes probably also use the same COGAG configuration illustrated for the KDX-II's.

 

[Solaris]

Here is another (highly technical) article about COGAG's on the Burkes and the difficulties of ramping up ship's speed efficiently by controlling pitch and successively adding more GT's.

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One part states that a single GT in "trail shaft" mode can drive the ship to a maximum speed of 22 knots! Trail shaft mode refers to only one shaft being powered and the other shaft "windmilling", which I think probably means freely rotating without power.

Anyway, getting back to the 055, I suppose if this type of arrangement is that common, it may be the most efficient? arrangement for COGAG's in general. It does also cement the intake-stack-stack-intake order for the topsides of these types of ships.

 

[Solaris]

Clearly I am bored out of my mind:

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Props to OP of course.

 

[Blitzo]

Nice, but going from the mock up, i think the "blocks" on the flank sides of the main smokestack will remain on the real thing, so amy hypothetical intake configuration will have to account for their presence.