BBG(X) - DISCUSSION ONLY

[johnpjones1775]

Fixed that for you.




The USN has decided that they will not do that.

Must have both full Mk41, a dozen CPS big-tubes (36x CPS, and could be re-swapped for 7x Tomahawks), and guns. Else you cannot get the ship with the needed capabilities in the right place at the right time.




I don't know why the Administration proposal has not specified the big BMD arrays, since the ship has the physical volume for those 28ft, 69RMA arrays.

The US hasn’t decided shit.
The most unqualified DoD and DoN leadership in generations, possibly ever have decided they want to stroke the president’s tiny mushroom shaped ego.

BBGX will not survive the end of this administration. BBGX will probably not survive 2027.

It doesn’t matter how many munitions you have if you don’t have enough shooters to use them in a timely manner.

It doesn’t matter if I have 1million rounds of 5.56 and only 1 rifle and 1 magazine, and I’m under attack by 40 people with pistols and a dude with a rifle.
However you missed my point completely. PLAN’s numbers are mostly from ships of equal or less capability as an ASuW armed LCS, meaning most of those numbers are of limited utility in a high end war, and building a bunch of simple ships would be a better counter than build a limited number of wonder weapon ships.

 

[Josh_TN]

You cannot effectively command from thousands of miles away. Even with satellite comms, you don't have as much data as people closer to the action.

Not to mention that sat coms can be jammed or outright destroyed, so now you have no comms.

Plus, LCCs have a very large command crew they need to haul around. IIRC over 600 bodies (~200 officers and ~400 enlisted).

What form of communication do you expect these platforms to use and over what range? How close to the Chinese coast do you expect them to go?

 

[Dilandu]

As I see it, the Navy's requirement for BBG numbers is on the order of 1-2 per carrier group for a total of ~12 or ~24, plus 2 for hosting the Amphibious Command for the 4 MAFs, plus one for each of the 7 Numbered Fleets to act as fleet flagships. That makes 21 on the low end and 33 on the high end.

Let's look from industrial point of view. The best solution for BBG(X) construction programme would be to re-purpose Ingalls shipyard to concentrate soley on them. I.e. cancel the San-Antonio class procurement, and limit Arleigh Burke's production to Bath Iron Works.

By doing that, USN would have two building docks large enough for BBG(X) available on Ingalls - and still have DDG production running at Bath. Since there would be far fewer battleships constructed at each moment than destroyers that they replaced on Inglass construction schedule - there would be no components bottlenecks; a pair of battleships would require no more components than four destroyers they would replace.

So from industrial point of view, the BBG(X) program is solid. USN could likely got one launched every two years (like San-Antonio class), while still getting Flight III Burke's in production to replace older model DDG's.

 

[Dilandu]

How close to the Chinese coast do you expect them to go?

About 2500 km - so they could hit targets 1000 km deep into continent with their hypersonics.

 

[Josh_TN]

Double posting because I want this to be entirely separate.

As I see it, the Navy's requirement for BBG numbers is on the order of 1-2 per carrier group for a total of ~12 or ~24, plus 2 for hosting the Amphibious Command for the 4 MAFs, plus one for each of the 7 Numbered Fleets to act as fleet flagships. That makes 21 on the low end and 33 on the high end.

Also, assuming that we are fitting them with the big 69RMA BMD arrays, there is an argument for a few more to sit up around Greenland on patrol like how the Japanese will use their ASEVs.

The U.S. cannot afford anything like that. This project will just be canceled even by a republican administration, or just Congress.

 

[cccgong]

Okay, that's possible.

I don't think it's likely, but I will accept it as possible.

I don't think it'd take all that much work to get the 69RMA antennas validated, you're just adding more RMAs to an already functional antenna.




You cannot effectively command from thousands of miles away. Even with satellite comms, you don't have as much data as people closer to the action.

Not to mention that sat coms can be jammed or outright destroyed, so now you have no comms.

Plus, LCCs have a very large command crew they need to haul around. IIRC over 600 bodies (~200 officers and ~400 enlisted).

There is no difference between the data you get 500 and 3000 miles away now. Normal coms will be easier to jam. Sat com sat can literally starlink sats, which are impossible to all take out unless you want to use nukes.

View attachment 810437

See this link for some of the sim screenshots. It’s some data from a hack of a major Chinese defense super computer center. It does not look like the carrier would survive a single hit mid ships.

 

[Scott Kenny]

The U.S. cannot afford anything like that. This project will just be canceled even by a republican administration, or just Congress.

Doesn't change the operational requirement.

Just changes how you pay for it.

 

[Sferrin]

There is no difference between the data you get 500 and 3000 miles away now. Normal coms will be easier to jam. Sat com sat can literally starlink sats, which are impossible to all take out unless you want to use nukes.


See this link for some of the sim screenshots. It’s some data from a hack of a major Chinese defense super computer center. It does not look like the carrier would survive a single hit mid ships.

They're guessing at best, and doesn't pass the sniff test. Not that I think they're impossible to sink but not with something that small, unless it's got a nuke. Consider the damage Enterprise took.

 

[EmoBirb]

I wouldn't necessarily go as far as saying this ship will be cancelled in the near future. Mostly because that would be further years wasted with no new surface combatant in sight. The habit of axing programs without an alternative already in place is among the many reasons why the USN has turned into a bit of a joke over the last two decades.

It's more likely that the program will be rebranded, away from BBG(X) and back to DDG(X) or more fittingly CG(X). Furthermore, adjustments to the program goals could be made, compromises, cut capabilities, measures meant to improve projected fleet size and reduce manufacturing cost.

But ultimately a new surface combatant will have to emerge, and just like how BBG(X) is seemingly born out of the DDG(X), it's more than likely that this program will be transformed into something different if it's deemed suitable. Ideally certain technologies and design choices developed and made during the development process to this point will be kept in order to not waste several years of R&D.

Now, admittedly, I'm probably being very generous towards the USN and government of theirs in general here. Because based on their track record since I've been alive, nobody should get their hopes particularly high. Morons will always find a way to self sabotage. So Ticonderoga and Arleigh-Burke replacement may happen in the lifetime of my children, maybe.

 

[johnpjones1775]

They're guessing at best, and doesn't pass the sniff test. Not that I think they're impossible to sink but not with something that small, unless it's got a nuke. Consider the damage Enterprise took.

It doesn’t really matter if it sinks the carrier outright. It just needs to do enough to a carrier outright of the fight.

 

[johnpjones1775]

I wouldn't necessarily go as far as saying this ship will be cancelled in the near future. Mostly because that would be further years wasted with no new surface combatant in sight. The habit of axing programs without an alternative already in place is among the many reasons why the USN has turned into a bit of a joke over the last two decades.

It's more likely that the program will be rebranded, away from BBG(X) and back to DDG(X) or more fittingly CG(X). Furthermore, adjustments to the program goals could be made, compromises, cut capabilities, measures meant to improve projected fleet size and reduce manufacturing cost.

But ultimately a new surface combatant will have to emerge, and just like how BBG(X) is seemingly born out of the DDG(X), it's more than likely that this program will be transformed into something different if it's deemed suitable. Ideally certain technologies and design choices developed and made during the development process to this point will be kept in order to not waste several years of R&D.

Now, admittedly, I'm probably being very generous towards the USN and government of theirs in general here. Because based on their track record since I've been alive, nobody should get their hopes particularly high. Morons will always find a way to self sabotage. So Ticonderoga and Arleigh-Burke replacement may happen in the lifetime of my children, maybe.

After midterms a new Congress will likely axe the program, and reinstate DDGX, even if it grows from 15k tons to 18-20k tons.

 

[Scott Kenny]

It's more likely that the program will be rebranded, away from BBG(X) and back to DDG(X) or more fittingly CG(X). Furthermore, adjustments to the program goals could be made, compromises, cut capabilities, measures meant to improve projected fleet size and reduce manufacturing cost.

This is entirely possible. If the USN can get all the features they want in ~22ktons, it gives them the appearance of offering a deal to congress to pay for the full ship they need (~128+ Mk41, 12x CPS big tubes/36x CPS missiles, gun(s), 69RMA radars, flag CIC and staff space) in a less expensive package than the full BBGX. And they're going to call it a CGX because that's what it really is.

However, all the stuff the Navy needs in the ship will not make losing ~13ktons of steel and air a much cheaper ship.

 

[Josh_TN]

How did the Ticos manage to carry sufficient flag spaces and personnel? Outside of the increased top weight and power/cooling for the ABM radar, what drives these extreme size requirements?

 

[Josh_TN]

Doesn't change the operational requirement.

Just changes how you pay for it.

At some point Congress just says to fight with you have or change the requirement. Somehow the USN manages without 30,000 ton escort ships now.

 

[cccgong]

They're guessing at best, and doesn't pass the sniff test. Not that I think they're impossible to sink but not with something that small, unless it's got a nuke. Consider the damage Enterprise took.

It’s an explicit dynamic simulation run on very large super computer cluster. With how much espionage the Chinese have done, I’m confident they have design documents or close enough for the Nimitz. They of course have their own data for the DF 21. So the only question is how good are there simulation guys. From the success of their other programs, I would say they should be quite good.

If you looked at the description of their DF 21 model, you can see that it has a large tungsten penetrator mass. This means it likely hits at hypersonic speeds, unlike many other ballistic missiles. With this, I have no reason to doubt the validity of their simulations.

I realized I forgot to paste the link

https://twitter.com/x/status/2036750151818055782

View: https://x.com/texhnolyze_d/status/2036750151818055782?s=46

 

[MadRat]

I wouldn't want too many corvettes just because China has them. I want ships that can perform real, serious missions.

The BBG(X) could get by with a two sided 57RMA array. The 69RMA has never been really necessary for BMD.

 

[cccgong]

I wouldn't want too many corvettes just because China has them. I want ships that can perform real, serious missions.

The BBG(X) could get by with a two sided 57RMA array. The 69RMA has never been really necessary for BMD.

And you happen to have simulation data showing that 57 rmas is good enough? When you will be near blind across a nearly half the directions things could be coming in from?

 

[EmoBirb]

It’s an explicit dynamic simulation run on very large super computer cluster. With how much espionage the Chinese have done, I’m confident they have design documents or close enough for the Nimitz. They of course have their own data for the DF 21. So the only question is how good are there simulation guys. From the success of their other programs, I would say they should be quite good.

If you looked at the description of their DF 21 model, you can see that it has a large tungsten penetrator mass. This means it likely hits at hypersonic speeds, unlike many other ballistic missiles. With this, I have no reason to doubt the validity of their simulations.

I realized I forgot to paste the link

https://twitter.com/x/status/2036750151818055782

View: https://x.com/texhnolyze_d/status/2036750151818055782?s=46

The guy who wrote the article said YJ-21, which is different to DF-21(D). Furthermore destroying the bridge as in the simulation (which is all that is shown there) is a mission kill, which is also stated. However this wouldn't sink a carrier. For that you'd need a more substantial hit, possibly breaking the keel of the ship. Which would in turn prerequisite the tungsten penetrator going all the way through the ship, not breaking apart halfway through.

It's possible to sink a carrier, and I'm more than willing to believe it can be done in a single blow even with conventional means (after all, a heavy torpedo should be able to do the same). However nothing in the write up or provided graphic suggested that the simulated YJ-21 is able to do that. I have neither access to the files used, nor can I read chinese, thus I can't verify the veracity of what this guy typed in his article.

 

[cccgong]

The guy who wrote the article said YJ-21, which is different to DF-21(D). Furthermore destroying the bridge as in the simulation (which is all that is shown there) is a mission kill, which is also stated. However this wouldn't sink a carrier. For that you'd need a more substantial hit, possibly breaking the keel of the ship. Which would in turn prerequisite the tungsten penetrator going all the way through the ship, not breaking apart halfway through.

It's possible to sink a carrier, and I'm more than willing to believe it can be done in a single blow even with conventional means (after all, a heavy torpedo should be able to do the same). However nothing in the write up or provided graphic suggested that the simulated YJ-21 is able to do that. I have neither access to the files used, nor can I read chinese, thus I can't verify the veracity of what this guy typed in his article.

Sorry I typed the wrong missile. It goes well beyond destroying the superstructure. You can see it punch through all decks to the hull and the hull suffers significant strain. The fires + radiation leaks will do a great deal too if the hull isn't breached.

Also this is for a ship ~3x the displacement of the BBGX it would easily punch through the hull of a BBGX.

 

[johnpjones1775]

This is entirely possible. If the USN can get all the features they want in ~22ktons, it gives them the appearance of offering a deal to congress to pay for the full ship they need (~128+ Mk41, 12x CPS big tubes/36x CPS missiles, gun(s), 69RMA radars, flag CIC and staff space) in a less expensive package than the full BBGX. And they're going to call it a CGX because that's what it really is.

However, all the stuff the Navy needs in the ship will not make losing ~13ktons of steel and air a much cheaper ship.

There’s almost no chance that they label it a cruiser.

 

[MadRat]

And you happen to have simulation data showing that 57 rmas is good enough? When you will be near blind across a nearly half the directions things could be coming in from?

What are you even going on about? At most you would not have BMD coverage 60 degrees front and aft, hardly anywhere near what you are going on about. You do not need 360 degree BMD coverage. And you can go far less sophisticated radars in those two narrow strips of coverage.

 

[cccgong]

What are you even going on about? At most you would not have BMD coverage 60 degrees front and aft, hardly anywhere near what you are going on about. You do not need 360 degree BMD coverage. And you can go far less sophisticated radars in those two narrow strips of coverage.

It's 2 seperate questions. How do you know 57 RMA is good enough when the navy was looking into 69.

US ships have 4 sets of arrays so you would be losing BMD coverage over 180 degrees. Also you have degraded quality at the edge of each array's field of view.

I posted SPY6 v1 costs in another thread here. It's about 1 million per RMA. You'd be saving maybe 25 million going from 69 to 57 RMA for 2 faces and 64 million by going from 69 to 37 RMA on the other 2 faces. That's a total savings of 90 million which is almost inconseqeuential (0.5%) when we talk about the 17B cost of the ship. RMA unit costs might also fall further when you're buying 2x of them at once vs SPY6 v1

 

[Josh_TN]

The problem with more RMAs is probably more topside weight than up front cost. It requires a larger ship for stability.

 

[cccgong]

The problem with more RMAs is probably more topside weight than up front cost. It requires a larger ship for stability.

It's a 35kt+ ship it'll be fine. As the ships they were looking at mounting 69RMA one weren't nearly this big.

 

[Scott Kenny]

At some point Congress just says to fight with you have or change the requirement. Somehow the USN manages without 30,000 ton escort ships now.

In case you haven't noticed, the floor for minimum capability has risen greatly.

FFS, the baseline Frigate pretty much needs BMD capabilities, nevermind the larger ships.

It's possible to sink a carrier, and I'm more than willing to believe it can be done in a single blow even with conventional means (after all, a heavy torpedo should be able to do the same). However nothing in the write up or provided graphic suggested that the simulated YJ-21 is able to do that. I have neither access to the files used, nor can I read chinese, thus I can't verify the veracity of what this guy typed in his article.

The America SINKEX showed that it would take an obscene amount of damage to sink a carrier. IIRC America was hit by no less than 4x Mk48s and still had to be scuttled. After a week of catching weapons.

 

[Josh_TN]

In case you haven't noticed, the floor for minimum capability has risen greatly.

FFS, the baseline Frigate pretty much needs BMD capabilities, nevermind the larger ships.

At some point the defense is simply unworkable. Also, what the hell is the point of that new SDA constellation if not to provide target grade tracks?

Honestly I never understood why tracking a missile coming straight for you has such obscene aperture and power requirements; the Burke’s seem to be able to target BMs just fine.

 

[cccgong]

The America SINKEX showed that it would take an obscene amount of damage to sink a carrier. IIRC America was hit by no less than 4x Mk48s and still had to be scuttled. After a week of catching weapons.

A carrier with all the flammable and explosives removed. And one they are trying to sink slowly so they can evaluate the effect of various weapons on it

At some point the defense is simply unworkable. Also, what the hell is the point of that new SDA constellation if not to provide target grade tracks?

Honestly I never understood why tracking a missile coming straight for you has such obscene aperture and power requirements; the Burke’s seem to be able to target BMs just fine.

The Burkes are targeting missiles with long warnings and target tracks from other radars in an ECM free environment. Additionally these missiles are not dumping decoys (so minimal discrimination is required), nor are they performing mid course maneuvering, and the ships were positioned optimally for intercept. Even with all of this hit rates didn’t seem great.

 

[DJK]

I saw a thread somwhere discussing the twin island arrangement, not sure if in relation to CG(X) or BBG(X). Apart from allowing more separation between stacks and therefore main engine rooms, there was a suggestion that redundant CICs would be desirable. Maybe more of a backup CIC than full redundancy, to allow fire fighting in the main one. I think having redundancy in AEGIS, SONAR & CEC systems would be more important, which are probably already duplicated.

DDGX or any similar platform fills defensive roles that will not be going away no matter what other weapons are adopted: AW, ABM, and to a lesser degree ASW. No matter what offensive strategy is chosen, these missions will need to be performed, and ABM in particular is size and power intensive.

Core roles of the DDG/FFG fleet.

But it is pointless to add offensive roles to defensive platforms, and surface ships have been relegated to largely defensive roles since WW2. 96 mk41 cells is a perfectly reasonable number if they are solely filled with defensive weapons, especially if reloading at sea becomes truly effective. Adding offensive weapons and missions just dilutes defensive capabilities, since now you have a more expensive ship that can still only be in one location.

But i struggle to imagine how offensive weapons bigger than Tomahawks could go onto LUSVs. Maybe this would really require something like the original missile barge concept, fitted with bigger VLS for the CPS missiles. Presumably minimally manned. Armed for self defence, including with PAC3 and rapid fire unmanned guns.

We just shouldn’t add stupid offensive capabilities like ‘rail guns’ for no real reason.

Or CPS. Anything carrying CPS (or TLAM for that matter) has to compromise either its size or loadout, while most of the cost of the warship is in its radar and defensive capabilities. More defence with guns and lasers helps, but you may need all your vls cells.

The ship with CPS have limited defensive missile supply & could not replace the ship without them. The ship without CPS have no heavy strike capability & could not replace ship with CPS. They specialized to perform different functions, with different tactical niches. It would be a constant headache to ensure that both classes of ships are in service in required numbers, to form groups, to make operation plans.

The headache comes from needing several ships, and in different places, but only having one that does everything. The possible DDG specialisation that still makes sense (with CPS on a different hull) could be to have one optimised for AAW commander with more VLS and CIC space. The other optimised for BMD with the bigger radar and maybe flag space instead of being the AAW commander. In 20 years when you have built enough of those, you might need another configuration like the primary laser defender or something else. The concept of midship hull modules was quite smart, I hope they come back.

Things like rail guns and CPS have no place in such a platform, and in any case the former does not exist in any usable form and probably won’t for a decade.

Agree! The issue might be that it needs a big platform to host such big missiles, which then requires self defence to match the value of the payload. Maybe they should go on LPDs with a few upgrades.

 

[Scott Kenny]

Honestly I never understood why tracking a missile coming straight for you has such obscene aperture and power requirements; the Burke’s seem to be able to target BMs just fine.

The Burkes are usually tracking a broadside target. Which means a much bigger RCS and honestly an easier track, IMO.

Something that is a ballistic CBDR is a much smaller RCS but is a much more obvious threat. And is likely to be jamming or have jamming support, be popping decoys left right and sideways, doing evasive maneuvers once back in the atmosphere, and probably with some kind of low-RCS design instead of a pure "ice cream cone of DOOM(tm)" RV shape.

 

[Josh_TN]

A carrier with all the flammable and explosives removed. And one they are trying to sink slowly so they can evaluate the effect of various weapons on it.

Ok, but that is a lot different than a DF-21 splitting the ship in two, which is basically impossible. I have no doubt a hit would cause a lot damage and fires.

 

[DJK]

Ok, but that is a lot different than a DF-21 splitting the ship in two, which is basically impossible. I have no doubt a hit would cause a lot damage and fires.

It would alao make a big hole... hopefully not through your reactor.

IMO CPS should live on a large separate hull type. The Lewis and Clark or San Antonio class would be off the shelf and capable of 20 knots. Throw some TLAMs on two if you want. Sticking huge ass CPS tubes on your ABM platform seems completely stupid when they require nothing like the electronics, power generation, etc. of the AD ship and have a range over a couple thousand miles (and probably minimum ranges in the high hundreds).

Im sure a San Antonio dedicated to CPS could have its bow optimised for whatever displacement the CPS results in. It might also be able to launch smaller drones instead of carrying troops.

 

[cccgong]

Ok, but that is a lot different than a DF-21 splitting the ship in two, which is basically impossible. I have no doubt a hit would cause a lot damage and fires.

The sims show the YJ-21 penetrating all decks and causing a significant amount of damage to the hull though no clear penetration. I'm willing to bet the ship will be mostly lost at that point due to large numbers of fires leading to hull integrity compromise coupled with the existing hull damage and radiation and/or meltdown from a destroyed reactor (the missile will likely target a reactor). Reactor targeting is substantiated by the sims showing a missile hit exactly where one of the reactors is located

Aganist a ship 1/3 the displacement, it's going to punch straight through the ship.

 

[DJK]

I do not believe the 57mm mount requires manual loading.

Not above deck. Sorry i was thinking of why you couldn't put a 30mm next to the laser.

 

[johnpjones1775]

There’s almost no chance that they label it a cruiser.

One thing i did like about BBG(X) was the idea of having a forward mk45 5" and then the two mk110 port and starboard. A third mk110 aft would give 360° coverage, and then you have laser and smaller guns on raised platforms. However, any gun that needs humans on deck to reload cannot be within visual of the laser, but i think the 40mm option like RN gives better options to have overlapping fields of fire.

A mixed secondary battery of 40mk4s and mk110s is pretty silly, just like the British frigate mixing 40mk4s and mk110s is silly.
They’re so close it makes no sense to split your ammo types up. Just go all 57 or all 40 ffs

 

[NMaude]

IIRC America was hit by no less than 4x Mk48s and still had to be scuttled. After a week of catching weapons.

Wasn't it a SEAL-team that scuttled it?

 

[Scott Kenny]

IMO CPS should live on a large separate hull type. The Lewis and Clark or San Antonio class would be off the shelf and capable of 20 knots. Throw some TLAMs on two if you want. Sticking huge ass CPS tubes on your ABM platform seems completely stupid when they require nothing like the electronics, power generation, etc. of the AD ship and have a range over a couple thousand miles (and probably minimum ranges in the high hundreds).

If your BMD radars require a large hull with lots of volume, might as well stick CPS on them.

What is broadside in this context? Or CBDR?

Broadside = side on
CBDR = Constant Bearing Decreasing Range. A collision course.

Wasn't it a SEAL-team that scuttled it?

I'd expect it was EOD, not SEALs. Just in case any of the ordnance that hit didn't go off.

 

[MadRat]

And you happen to have simulation data showing that 57 rmas is good enough? When you will be near blind across a nearly half the directions things could be coming in from?

You mean I need data when the USN deemed DDG(X) to be adequate for BMD with 57 RMA? If money was no cost then I would want two 57 RMA each side and at least a 9 RMA radar front and back. if money is a problem then one 57 RMA each side is pretty significant. It is not a lone wolf cruiser, it is to be integrated with multiple large radars, therefore the concentration can be in using vertical space for more than radars.

In a shooting war I expect the enemy to attempt overmatch of targets. It is not silly in any way to have enough weapons for 500+ weapons being concentrated on high value targets like CVNs and BBG(X). So it is not stupid IMHO to throw over two dozen lighter weapons around it each capable of taking down missiles and bombs.

 

[Dilandu]

You mean I need data when the USN deemed DDG(X) to be adequate for BMD with 57 RMA

It was before the Iranian war, which, I suspect, gave US a lot more data to play with.

P.S. Just thinking... but maybe the decision to switch from DDG(X) to BBG(X) was made after experience of 2025s Iran-Israel war? USN participated in Israel missile defense, and its quite possible that Navy concluded - previous assumptions were wrong, destroyer-size radars aren't efficient enough.

 

[DJK]

A mixed secondary battery of 40mk4s and mk110s is pretty silly, just like the British frigate mixing 40mk4s and mk110s is silly.
They’re so close it makes no sense to split your ammo types up. Just go all 57 or all 40 ffs

It may seem silly but they did it for some reason that I'm not privy to.

I imagine 57mm is smallest gun ever likely to get a guided AA projectile and therefore extended range sub-calibre performance, commonality with a major ally, and high enough rate of fire to be useful after switching to 3P for more close in, so thats your main gun. 57mm would be mostly screening targets outside the 40mm range and too big to put very many on a Type-31 sized frigate

Bofors 40mk4 is the smallest CIWS sized gun with below-deck magazine (a useful feature for minimal manning and maximum availability), designed originally for AA, and potentially the most reliable gun available for the inner layer.

Maybe RN had different reasons, but some advantages anyway.

If your BMD radars require a large hull with lots of volume, might as well stick CPS on them.

Thats what i thought too, but then CPS just makes the hull even bigger and adds even more to the top weight issue. If there was a convergence of the two roles then combine them o to one vessel. But if you want to keep your CPS at a certain range for standby and another range for firing, that might not be the location you want for protecting a fleet from DF-21 threats. Your fleet might not want to lose ballistics defence for a couple of days while you go off to fire your own hypersonics. Plus, CPS probably makes your BMD vessel more expensive with less than optimal defensive loadout, so less effective in both roles.

Having said that, if the next generation of SM3 etc needed more range, maybe some bigger cells are useful afterall. I would still argue that a mix of Mk-41 and Mk-57 should allow for a bigger future BMD missile, and peripheral VLS might also reduce damage to your Mk-41 from side impacts, if they fit.

 

[Josh_TN]

Another issue is that if you want to reload CPS, your BDM ship is offline. Where as it seems mk42 reloads will take place much more forward - if not at sea, then at least in sheltered water forward rather than at a location with fixed infrastructure. CPS is large enough that there is no getting around specialized handling equipment.