Japan 20000t SPY-7 guided missile destroyer/cruiser

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In the record breaking 5.6 trillion yen 2023FY budget request, the Japanese MoD has put in a request for a class of 2 new ships to utilize the SPY-7 systems originally planned to be used as AEGIS Ashore systems. The current outline calls for a ship that is 210m or less in length, 40m or less in beam and has a standard displacement of 20000t. This would make the new class of ship larger than the Hyuuga-class DDH and potentially larger than the Izumo-class at full load meaning it would be the largest JMSDF vessel ever built. The reason for the immense size and specifically the wide beam is to provide a stable platform to provide maximum performance of the radar. Typical of recent Japanese destroyer classes, this new class of ship will have 2 ships with the first having a planned commission date of 2027 and the second in 2028.
 
Quite interesting. I tried finding more about the idea, from English language online sources - but found nothing so far. The Japanese article above is a bit confusing, sometime stating 2010s and sometimes 2020s for the ship service date. Plus, it'd be nice to know where the assumptions of ship's size came from.
 
The original idea for this ship was a SWATH or catamaran hull for better stability. Thoae concepts did not really look like traditional warships, more just radar platforms with some VLS strapped on. We may see the same with these new SPY-7 monohull ships, less cruiser, more fleet auxiliary with a very large radar. However, reports that the new ships will also carry Type 12 cruise missiles could imply that that want a more conventional all-around warship.

Here is a concept drawing of the previous idea.

1662030265705.png
 
Regarding the planned Aegis ship replacements for Japan's abortive Aegis Ashore procurement:

The Yomiuri Shimbun
16:48 JST, August 17, 2022
To increase deterrence against North Korea’s missiles, the government plans to place domestic long-range cruise missiles on two naval vessels equipped with the Aegis system it plans to build, it was learned Tuesday.
These missiles are capable of striking land-based targets as the ships will be designed on the expectation that the vessels have “counterattack capability” such as to destroy an enemy’s missile launch site in the name of self-defense.
To keep down construction costs, it has also been settled that the ships will be built using a typical single hull, according to several government sources.
The government decided in December 2020 to build two Aegis system-equipped ships as an alternative to deploying Aegis Ashore, a land-based interceptor system. The government gave up deploying Aegis Ashore due to factors including opposition from the public.
The plan is for the eight existing Aegis-equipped ships of the Maritime Self-Defense Force to operate in such waters as those around the Senkaku Islands of Okinawa Prefecture, while the new Aegis system-equipped ships are expected to be constantly deployed in the Sea of Japan to keep an eye out for ballistic missile launches by North Korea.
The SPY-7 radar for Aegis Ashore will be equipped on the new vessels. The government has already signed a contract to purchase the state-of-the-art radar from a U.S. firm. SM-6 missiles, which can intercept cruise missiles, have also been decided on as equipment for the two ships.
In addition to the advanced radar and missiles, the Aegis system-equipped ships are likely to carry cruise missiles that will be upgraded versions of the Type 12 surface-to-ship missile currently used by the Ground Self-Defense Force. After the upgrades, the missile’s range will extend to about 1,000 kilometers and it will be mounted on naval vessels.
The government will revise three national defense-related documents, including the National Security Strategy, by the end of the year, and has been coordinating its policy so that the Self-Defense Forces will be able to possess counterattack capability.
If the Aegis system-equipped ships are mounted with long-range cruise missiles, it could help the country build up deterrence.
Concerning the hull’s design, however, the government had originally considered constructing the ships with multiple hulls to make them less susceptible to the impact of waves.
Because few actual naval vessels have been developed with multiple hulls and the construction costs of such ships are likely to balloon, the government has decided on a single hull.
The government is expected to announce the newly worked-out plan shortly.
Now that the hull type has been decided, the Defense Ministry hopes to start designing the hull as soon as possible. It plans to include the related outlays for the construction in its budgetary request for fiscal 2023.
It is expected to take more than five years for the new hull to be completed.

I suspect that the decision not to go with a multi-hull design may end up backfiring in the long term.
 
I suspect that the decision not to go with a multi-hull design may end up backfiring in the long term.

Same. The SWATH concept wasn't so untested that it would be a severe design risk, and it was much better suited to the long loitering mission than a large monohull.

It strikes me that they missed an option. The location of AEGIS ashore would have been well known, so why not move it to an offshore platform like a jack-up rig. Eliminate the fall-back booster risk that made people upset with AEGIS Ashore but save the expense of an actual mobile ship platform.
 
1662072502599.png
In this configuration, the HII's "future surface combatant" is 209 meters (684ft) in length with a beam of 32 meters (105 ft) and a max. displacement of 27,000 tons. The speed is 20+ knots and expected crew is 161 sailors (a significant drop compared to the 300+ crew complement aboard the Ticonderoga-class).
My best guess is we see an LPD hull form as HII's concept for a BMD LPD lines up well with the specs given by the MoD including the crew count since I have seen some sources say a 110 man crew. I don't know about MHI, but Mitsui has an LPD design which could be modified for increased deck space for VLS mounting. 1662072543918.jpeg
The other option I see is a traditional destroyer hull form based on either the Hyuga or Izumo hull since both are essentially enlarged destroyer hulls.
Personally I would want to see a large surface combatant style like the Russian Navy Kirov class based on an Izumo hull since it would be covering more than BMD with the Type 12 ASCM. The speed of the Izumo hull would also give it the ability to keep up with the rest of the fleet while the LPD hull would slow it down by almost 10 kts.
 
Quite interesting. I tried finding more about the idea, from English language online sources - but found nothing so far. The Japanese article above is a bit confusing, sometime stating 2010s and sometimes 2020s for the ship service date. Plus, it'd be nice to know where the assumptions of ship's size came from.
It's because the translator mistranslates due to the difference in Japanese expressions.

One ship will be built in FY2027 and FY2028.
 
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Quite interesting. I tried finding more about the idea, from English language online sources - but found nothing so far. The Japanese article above is a bit confusing, sometime stating 2010s and sometimes 2020s for the ship service date. Plus, it'd be nice to know where the assumptions of ship's size came from.
As barrett has already said, it's just the translator misinterpreting. The dates are marked as 27年 and 28年 corresponding to the western years 2027 and 2028, but the translator assumes it means Heisei era dates which of 27年 and 28年 which correspond to 2015 and 2016. The actual specs of the ship come directly from the Japanese MoD in their preliminary budget outline where they just name the projects without allocating specifying funding they want to request.
 
I'd say US navy jumps on this bandwagon get yourself a true BMD cruiser with space and depth for boost phase interceptors in future.
 

It strikes me that they missed an option. The location of AEGIS ashore would have been well known, so why not move it to an offshore platform like a jack-up rig. Eliminate the fall-back booster risk that made people upset with AEGIS Ashore but save the expense of an actual mobile ship platform.
The problem with that is twofold:

It’s a fixed installation which needs protecting from NK infiltrators & subs.

It would also likely garner complaints from Japanese fishermen because of “radiation” and suchlike.
 

It strikes me that they missed an option. The location of AEGIS ashore would have been well known, so why not move it to an offshore platform like a jack-up rig. Eliminate the fall-back booster risk that made people upset with AEGIS Ashore but save the expense of an actual mobile ship platform.
The problem with that is twofold:

It’s a fixed installation which needs protecting from NK infiltrators & subs.

It would also likely garner complaints from Japanese fishermen because of “radiation” and suchlike.

The land-based fixed sites would also need protection against saboteurs. The mobile ships also require protection against subs -- more Chinese than NK at this point, to be honest. That's part of the logic behind a ship platform -- fall-back booster risks are the public complaint but the ability to station ships in the East China Sea for intercepts against China rather than NK is likely the real planning issue.

In retrospect, that does somewhat argue against truly fixed offshore platforms. But something like the Sea-Based X-Band Radar platform would have worked.
 
I'm curious about the radar specification, so far my readings indicates that SPY-7 was kinda very close to SPY-6 in architecture including scalability. Unfortunately no information of the size of the radar. However going with US Navy specification for 6.1 m diameter radar, the SPY-7 here might have about 82 RMA's This could translate to about 29 dB loop gain/sensitivity advantage compared to baseline SPY-1 and 3 dB over 69 RMA AMDR.

Range wise the radar can detect 2 sqm RCS target at approximately 1475 km, while something like 10 sqm of side aspect of ballistic missile at 2206 km.
 
I'd say US navy jumps on this bandwagon get yourself a true BMD cruiser with space and depth for boost phase interceptors in future.
One could hope. They really need to come up with a bigger cell though.
 
I'd say US navy jumps on this bandwagon get yourself a true BMD cruiser with space and depth for boost phase interceptors in future.
One could hope. They really need to come up with a bigger cell though.
It seems that the trend for new cruisers are bigger cells (Korean KDX-III patch 2 or Chinese type 055) so I doubt the Japanese not gonna develop their own given these are japan's 2 geopolitical competitors.
 
I'd say US navy jumps on this bandwagon get yourself a true BMD cruiser with space and depth for boost phase interceptors in future.
One could hope. They really need to come up with a bigger cell though.
It seems that the trend for new cruisers are bigger cells (Korean KDX-III patch 2 or Chinese type 055) so I doubt the Japanese not gonna develop their own given these are japan's 2 geopolitical competitors.
I thought we were talking about the US navy..
 
I thought we were talking about the US navy..
I meant US navy can piggyback on a joint venture. Regardless it's technologically it's not a big risk to build a larger cell so they could go solo too.
 
The USN is developing a (much) larger cell? I mean, what do you guys think they're going to install on the Zumwalts instead of the cannons?
 
The USN is developing a (much) larger cell? I mean, what do you guys think they're going to install on the Zumwalts instead of the cannons?
That's going to be a one-off, virtually useless for most applications.
 
The USN is developing a (much) larger cell? I mean, what do you guys think they're going to install on the Zumwalts instead of the cannons?
That's going to be a one-off, virtually useless for most applications.

We don't know that. The DDG(X) concept showed a payload module space that could accommodate something like those cells got Zumwalt. And we don't know that the primary VLS will be the current Mk 41 cell size. Could be Mk 57 cells, especially if they go with a Zumwalt style hullform.
 
The USN is developing a (much) larger cell? I mean, what do you guys think they're going to install on the Zumwalts instead of the cannons?
That's going to be a one-off, virtually useless for most applications.

We don't know that. The DDG(X) concept showed a payload module space that could accommodate something like those cells got Zumwalt. And we don't know that the primary VLS will be the current Mk 41 cell size. Could be Mk 57 cells, especially if they go with a Zumwalt style hullform.
The cell for the long-range missile going on the Zumwalts won't be used for anything else. They're not going to stuff 4 SM-6s in each one as an alternate loadout for example. Also, future missiles are already being constrained by the Mk41 cell which would indicate they're not looking at anything that would require the Mk57.

1662392690444.png
 
I must admit it still perplexes me why there hasn't been a centerline block Mk 57 development yet to replace the Mk 41 in new-build ships.
Surely its time to move on from a VLS designed in 1976....
 
The USN is developing a (much) larger cell? I mean, what do you guys think they're going to install on the Zumwalts instead of the cannons?
That's going to be a one-off, virtually useless for most applications.

We don't know that. The DDG(X) concept showed a payload module space that could accommodate something like those cells got Zumwalt. And we don't know that the primary VLS will be the current Mk 41 cell size. Could be Mk 57 cells, especially if they go with a Zumwalt style hullform.
The cell for the long-range missile going on the Zumwalts won't be used for anything else. They're not going to stuff 4 SM-6s in each one as an alternate loadout for example. Also, future missiles are already being constrained by the Mk41 cell which would indicate they're not looking at anything that would require the Mk57.

View attachment 683612

It would be pretty foolish to commit to designing a >21-inch missile before the Navy has significant numbers of >21-inch launchers. But the USN clearly sees the need to go bigger, it just failed the necessary ship acquisition. I would not be at all surprised to see DDG(X) attempt the same future-proofing as DD-21.
 
I don't know if the Zumwalt VLS cells being developed to fire the Conventional Prompt Strike missile, a glide body hypersonic missile, is cold or hot launch, my guess cold launch with variant of the Trident VLS cell.

The submarine Trident VLS cell uses a cold/soft launch with a steam cannon system to eject the missile before the missile booster ignites above the surface whereas the Mk41 VLS cells hot launch, the cell must withstand the tremendous heat generated by the missile booster igniting in the cell with the heat not affecting missile in adjacent cells to cause cook offs, pros and cons for both cold and hot launch.

Would mention that the Zumwalt VLS cell in development will fit 3 CPS 34.5" dia missiles each, the four Ohio SSBN converted to SSGN had their VLS Trident cells modified to fire seven Tomahawks, 154 total, so think Zumwalt VLS could be modified to fire other missiles at future date. Additionally the CPS missile is not a program of record, still at prototype stage, if remember correctly some test failures and the current estimated cost of $100+ million each per missile may cause Congress to cancel if they think hypersonic scramjets offer a less expensive option?

PS The newer Chinese VLS cells on Type 055 are concentric and can launch hot or cold.

 
The USN is developing a (much) larger cell? I mean, what do you guys think they're going to install on the Zumwalts instead of the cannons?
That's going to be a one-off, virtually useless for most applications.

We don't know that. The DDG(X) concept showed a payload module space that could accommodate something like those cells got Zumwalt. And we don't know that the primary VLS will be the current Mk 41 cell size. Could be Mk 57 cells, especially if they go with a Zumwalt style hullform.
The cell for the long-range missile going on the Zumwalts won't be used for anything else. They're not going to stuff 4 SM-6s in each one as an alternate loadout for example. Also, future missiles are already being constrained by the Mk41 cell which would indicate they're not looking at anything that would require the Mk57.

View attachment 683612

It would be pretty foolish to commit to designing a >21-inch missile before the Navy has significant numbers of >21-inch launchers.
They already did. They built these bigger hypersonic missiles and there's no VLS for them in existence.
 
They already did. They built these bigger hypersonic missiles and there's no VLS for them in existence.

They decided to adopt an Army missile for a niche application and figure out how to deploy it. Not quite the same thing as a missile for fleet adoption. There needs to be an installed base of larger cells before they adopt a new larger missile as a fleet-wide standard.
 
They already did. They built these bigger hypersonic missiles and there's no VLS for them in existence.

They decided to adopt an Army missile for a niche application and figure out how to deploy it. Not quite the same thing as a missile for fleet adoption. There needs to be an installed base of larger cells before they adopt a new larger missile as a fleet-wide standard.
So far there is zero evidence they're even to the powerpoint stage of a Mk41 replacement. And the Mk57 (which still isn't big enough) appears to be dead as well.
 
I'd say US navy jumps on this bandwagon get yourself a true BMD cruiser with space and depth for boost phase interceptors in future.
In more sane times I'd suspect you would be correct there. Under the current administration & DOD/Armed Services leadership though...
 
So far there is zero evidence they're even to the powerpoint stage of a Mk41 replacement. And the Mk57 (which still isn't big enough) appears to be dead as well.

There's evidence that industry (specifically NG) continues to work on Mk 41 successor designs. They wouldn't be doing that if they thought there was no possibility of adoption. I think I heard that LM was also looking at alternatives, but I can't find a reference now.

 
So far there is zero evidence they're even to the powerpoint stage of a Mk41 replacement. And the Mk57 (which still isn't big enough) appears to be dead as well.

There's evidence that industry (specifically NG) continues to work on Mk 41 successor designs. They wouldn't be doing that if they thought there was no possibility of adoption. I think I heard that LM was also looking at alternatives, but I can't find a reference now.

I hope NG keeps pushing their Modular Launch System. That looks like it's got a lot of potential though it doesn't look to be the most efficient use of space.
 
Folks this is a Japanese SPY-7 equipped Aegis destroyer thread. I think it would be beneficial to make a separate thread for "USN VLS modernisation" or something along those lines and move/continue discussions there.
 
So the at least interim official designation for them is ASEV (Aegis system-equipped vessel).

From the Naval News article:

According to local newspaper reports, initial details of the ASEV point towards a massive ship: 210 meters long and 40 meters wide, with a standard displacement of 20,000 tons and a crew of about 110 people. Crew comfort onboard will be a priority as all crew members will be provided with private cabins. In terms of length and displacement, it is equivalent to the Izumo class DDH (248 meters long, standard displacement 19,500 tons), the largest vessel in the JMSDF, but it is more like a civilian vessel than a warship in that all crew members are given private cabins and the crew complement is quite low for a vessel of this size.

Defense Minister Yasukazu Hamada explained explained during a press conference held on September 2 the reasons for such a large vessel, as well as the rationale behind high crew comfort standards:

“The reason is to ensure seaworthiness, to be able to operate in rough weather, to improve the crew’s living environment for long-term offshore missions, and to be expandable to deal with hypersonic glide vehicles (HGVs) in the future.”

However, in addition to the reasons given by the Defense Minister, some believe that the hull was enlarged to solve the problem of the size and weight of the SPY-7, a radar manufactured by Lockheed Martin that will be installed on the ASEV. The Defense Minister also commented that the ASEVs are expected to be commissioned around March 2028 for the first vessel and March 2029 for the second vessel.


The primary role assigned to the ASEV is to free the JMSDF’s Aegis destroyers from their North Korea watch duties and to enable them to respond to China’s maritime expansion. Therefore, the ASEV does not inherently require air defense or anti-submarine warfare capabilities, its sole main focus being BMD. This is because North Korea does not currently possess such weapons to attack the ASEV.


However, according to press reports, the ASEV will be equipped with SM-6 missiles to deal with cruise missiles and anti-ship missiles, as well as an improved version of the Type 12 ship-to-ship missile that can attack surface targets as well as naval vessels and has a range of approximately 1,000 km. Therefore, the ASEV could become an asset that could respond not only to North Korean ballistic missiles, but also to attacks by Chinese ballistic missiles, HGVs, and cruise missiles. The question then would be how would the ASEV respond to the threat of Chinese submarines and anti-ship missiles. Above all, in this case, the ASEVs should probably be planned as a completely new type of warship, since it cannot be positioned as a mere alternative to the Aegis Ashore.
 
I think this particular statement from the article is rather a hostage to fortune at best:
Therefore, the ASEV does not inherently require air defense or anti-submarine warfare capabilities, its sole main focus being BMD. This is because North Korea does not currently possess such weapons to attack the ASEV.
 
I think this particular statement from the article is rather a hostage to fortune at best:
Therefore, the ASEV does not inherently require air defense or anti-submarine warfare capabilities, its sole main focus being BMD. This is because North Korea does not currently possess such weapons to attack the ASEV.
Fitted for, but not with?

Perhaps Japan has enough subs and frigates available for the Sea of Japan to mitigate any threats?
 
This article does seem to suggest that these are not giant destroyers or cruisers, but rather large vessels built to commercial standards with radar and VLS bolted on. Conceptually more like the USN's proposed SABMIS missile defense ship than a super CG.
 
Conceptually more like the USN's proposed SABMIS missile defense ship than a super CG.
I did wonder if that was the case when I read the first reports about this new class. However the tacking on of things like the counterattack role does to my mind suggest that, what ever the original intent was, the design may be evolving towards using naval standards overall in its design & construction, given that hybrid designs (combining naval and commercial specifications) seem to have been going out of fashion in recent times and using commercial spec for the hull would very likely end up not meeting requirements, since it probably will need a heavily bespoke design to fulfill (and that is assuming they don't ultimately decide to go for nuclear propulsion to enhance time on station and such). So it is possible that it will emerge as something more along the lines of an actual battlecruiser, or at least as a proper warship design.
 
assuming they don't ultimately decide to go for nuclear propulsion to enhance time on station and such

I cannot imagine the JMSDF even considering nuclear propulsion for this. Even disregarding the domestic politics, the timelines make it an impossible option. There is no available nuclear reactor available to Japan.

The possible inclusion of the Type 12 missiles to me signals that these ships will have excess volume due to seakeeping requirements and they see an opportunity to get the improved Type 12 to sea without typing up their main fleet units.
 

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