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Defense Ministry mulls potentially costly design for 2 new Aegis ships

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Good idea. Japan needs more ships.

-1 ( +6 / -7 )

I see what they are saying because a catamaran or SWATH (Small WAterplane Twin Hull) like the three SURTASS ships mentioned doesn't roll as much in heavy seas, which is better for the radars. I don't know what Japan's requirements are for these Aegis ships but if their design brief is for them to cruise around at low speeds in a limited geographic area and not something that has to run at higher speeds and greater distances with other fast naval forces, I would be tempted to build something on one of the many double hull tankers being sent to scrap yards in India, Bangladesh and Turkey. Big double hull that can take hits. The oil tanks could be divided so the center line is where working and living spaces are while the outer third on each side is filled with buoyant material that doesn't burn. I'd actually build an armored box down the center of the hull for working and living spaces, and to give the ship more structure to resist torpedo explosions underneath. A quiet propeller could be installed and a bubbler system installed around the hull to silence engine noises. Remove the original superstructure, build a new stealthy one with the Aegis radars, bury the command center deep in the center of the hull and add composite armor all over. Sort of a slow moving arsenal ship. Give it some ASW helicopters for self defense against Chinese subs. You could even add a big torpedo blister around the hull like many WWII combat ships had for extra torpedo protection. Keep it close to shore where it can be protected by land based units.

8 ( +8 / -0 )

Vaccinate the whole country..

Activate economy.

Solve social problems

buy new war ships
6 ( +7 / -1 )

Yes, very good, the best or nothing.

3 ( +3 / -0 )

I do not understand the need for multihull ships to carry the Aegis missile system. Modern tanks are able to maintain tracking for their cannon while traversing rough terrain. Wouldn't a similar system enable a ship to maintain tracking while on the ocean?

-2 ( +0 / -2 )

I do not understand the need for multihull ships to carry the Aegis missile system. Modern tanks are able to maintain tracking for their cannon while traversing rough terrain. Wouldn't a similar system enable a ship to maintain tracking while on the ocean?

It helps the radars maintain track on multiple targets. A tank is tracking only one target at a time. The tracking device is gyrostabilized, sort of floating on the turret. Aegis tracks hundreds per radar panel. They are much too big to sit on a support structure that is gyrostabilized in space. They are built into the superstructure. The wave guides and other electronics of those radars take up much of the interior of the superstructure. The radar also communicates with the missiles to give them mid course guidance updates, and the radar performs some electronic warfare functions against the incoming enemy missiles. In this application they are being optimized to track fast moving ballistic missiles rather than used as a general purpose air defense system that needs to track low flying cruise missiles, helicopters and aircraft. Sure it can work on a monohull but it works better on a catamaran. Another consideration is the ship's low observability. It is easier to control the ship's radar cross section if the ship is not pitching and rolling significantly. If the ship pitches and rolls a lot, it can have intermittent reflections a lot like a shiny object turning in the wind where the sun glints off the face when it is turned towards the sun. The reflection is not continuous but might be enough for an enemy to aim something at. Managing radar return is a big deal on combat ships. If you ever visit a modern Burk class DDG, you will see the railings are triangular instead of round and the undersides of bridge wings and other superstructure protrusions, antenna support structures and the like, are filled in and smooth underneath to reduce reflections as the ship rolls. On earlier designs there would be visible bracing under bridge wings.

4 ( +4 / -0 )

@1glenn

I do not understand the need for multihull ships to carry the Aegis missile system. 

The SPY-7 used in Aegis Ashore is too heavy, making the ship carrying it top-heavy and prone to roll-over.

A multi-hull ship is needed for the stability.

1 ( +3 / -2 )

@EisenachToday 

Good idea. Japan needs more ships.

Any cost-overrun on Aegis Ashore means a cut in other programs. Japan doesn't have a lot of money to spend on defense(Japan's weapons acquisition budget is 1/3rd of Korea and 1/10th of China, for example). There is a reason why only China and Korea have their own stealth fighters and why Japan's stealth fighter is nothing but a powerpoint presentation, Japan can't afford to spend as much money on weapons as China and Korea could.

Yea, it would be great if any cost overrun would simply be made up by a supplemental budget, but that's not the case. Already, the F-15J modernization program appears to be the victim of this cost cutting effort.

0 ( +3 / -3 )

The SPY-7 used in Aegis Ashore is too heavy, making the ship carrying it top-heavy and prone to roll-over.

No, that is not true at all. Where do these stories come from? AESA radars are scalable. Each module is an independent transmitter/receiver. You can scale the array (the octagonal shaped panel) to fit the size of the platform by adding or subtracting T/Rs to make larger or smaller (heavier or lighter) arrays. Same with AN-SPY-6. AN-SPY-7 is being installed on Spain's F110 class frigates and Canada's new Halifax class frigates. Both are mono-hulls of less displacement than any of Japan's current Aegis equipped ships. But by adding T/Rs to the array it can be as huge as the Long Range Discrimination Radar in Alaska. They all share the same T/Rs, just more or less of them, and software is adjusted to fit. AN-SPY-6 is being fitted to Arleigh Burke Flight III ships, the soon to be built Constellation Class frigates, the Ford Class aircraft carriers and will be back fitted to the San Antonio class LPDs. It is likewise scalable and the panels on the Constellations will be smaller versions of what is on the Burke Flight IIIs, which in turn are smaller versions of what is on the Ford class. One of the things that make AESA radars so capable, and so hard to detect and jam is that each T/R can use a different wave form on a different frequency. The electronics and software are able to take data from each T/R and turn this into a complete picture of the battle space.

4 ( +4 / -0 )

@Desert Tortoise

No, that is not true at all. Where do these stories come from?

https://news.yahoo.co.jp/byline/obiekt/20210410-00232044/

 また「イージス・システム搭載艦」はイージスアショア用に契約したロッキード・マーティン製SPY-7レーダーを搭載する予定で、従来のイージス艦用よりもレーダーパネル面積が大きい仕様を発注しているため

It's not the same radar panel as the Aegis destroyer radar panels, but much larger.

Hence putting Aegis Ashore panels on existing JMSDF Aegis destroyer designs make it top heavy and unstable.

2 ( +3 / -1 )

It's not the same radar panel as the Aegis destroyer radar panels, but much larger.

Hence putting Aegis Ashore panels on existing JMSDF Aegis destroyer designs make it top heavy and unstable.

Again, you do not understand these radars. Fact: AN/SPY-7 will be used on the Spanish F110 class and Canadian Halifax class frigates. Those are not even destroyers but frigates and both are monohulls. AN/SPY-7 fits a monohull suface ship. So does AN/SPY-6.

Fact: The AN/SPY-1 radars used on existing Aegis Ashore installations in Poland and Romania are the same panels used on Arleigh Burke Flight IIA DDGs. Current Aegis Ashore uses radars that are at sea now in ships that I am not hearing complaints about being top heavy (Atago class for example).

What makes and AN/SPY7 what it is are the individual Transmitter/Receivers, or T/Rs. You can make panels bigger or smaller by changing the number of T/Rs on the panel. Arrays can be different sizes and still be AN/SPY-7 radars. It's the same T/R on a Halifax that sits on the huge Long Range Discrimination Radar, just fewer of them than the big land based version. You are not going to drop something the size of the Long Range Discrimination Radar on a ship ( maybe on a 250K dwt tanker ) but that big radar has the same T/Rs as the smaller version of AN/SPY-7 on a frigate, just more of them and the greater number gives the radar greater range. Remember these radars are scalable. Same radar architecture, same T/Rs, just change the number to make the array bigger ( and heavier ) or smaller ( and lighter ) to fit the intended application.

The main rub against AN/SPY-7 when compared to AN/SPY-6 is that the former is still in development while the latter is fully tested, qualified and being installed on new build Arleigh Burke Flight III ships in the yards today. There is less risk using AN/SPY-6 than there is using AN/SPY-7.

3 ( +3 / -0 )

Btw, the three existing Hibiki class SWATHs (Small Waterplane Area Twin Hull) surveillance ships are not very large ships. Their hull would have to be scaled up by a factor of about 2.5 to match the displacement of a Ticonderoga.

2 ( +2 / -0 )

All this because there’s a “chance” that boosters “might” fall on to someone’s property if Aegis Ashore is used.

wouldn’t it be MUCH cheaper to buy up all the land in the booster zone?

Jesus, what a disgrace.

3 ( +3 / -0 )

The current "official" cost of the Tokyo Olympics is somewhere around $15 billion, with a suspected true cost of around double that. Just for a 17-day fantasy.

Perhaps if the government hadn't wasted all that money they'd have enough to defend the country from perceived external threats. And maybe a bit left over to build a vaccination booking system that works.

1 ( +2 / -1 )

Thanks to those trying to explain this matter.

I see that it is more complicated than I realized, and needs detailed research.

0 ( +0 / -0 )

All this because there’s a “chance” that boosters “might” fall on to someone’s property if Aegis Ashore is used.

wouldn’t it be MUCH cheaper to buy up all the land in the booster zone?

The booster used on SM-3 is called the Mk-72. It has a working time of 6 seconds and a specific impulse of 2200 m/s. So the booster is going to travel a slant range on the order of 13 km. Depending on the geometry of the intercept the missile trajectory may have a greater or lesser vertical component. After separation the booster will fall in a ballistic path to the ground. Draw a circle some 25 km or so from the launch site and the booster will probably land somewhere inside that circle. You don't know which direction because the enemies missiles could come from land, or maybe from a sub, meaning they could arrive from any point on the compass. The area of a circle is pi times the square of the radius, 25,000 meters (25km), or an area of 1963 km. That is an awful lot of real estate in a crowded country like Japan.

This is why the US Army requires all land based air defense missiles to be single stage. SM-3 is a ship based missile so where the booster lands isn't such a big deal. Having a 21 inch (5..3 cm) diameter booster come clanging down on somebodies roof or their car, or the middle of some kids playing, is considered bad form to put it mildly. Killing your friends to defend them isn't what we are trying to do.

1 ( +1 / -0 )

Mistakes in the above, should have said 1963 square km and that 21 inch diameter booster is 53.3 cm, not 5.3. It's a big piece of steel to have land on somebodies roof, car or ??????? Apologies for the errors.

0 ( +0 / -0 )

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