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Re: JMSDF Akizuki Class DDG (19DD AEGIS-like)

Jura said:

shen, or anybody, can you estimate what the difference would make placing the X-band antenna, say, 10 meters higher on a ship, with respect to the detection of a sea-skimming missile doing, say, 240 m/s? I of course assume the same radars and the trajectories of the same missiles and the answer would be, for example, "the detection at 25 instead of 20 kilometers"; if you don't want to post here, please email what you think to Krize1938_at sign_seznam.cz, thanks!

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I know people who have worked directly with the Japanese Naval design people. They know what they are doing. My guess is that they determined that the height they put it at was an optimum consideration for several factors where gaining an extra five kilometers in detection was weighed against other ship design factors.

Shen keeps indicating that the Akizuki is a "bad" design. So we are left to take his reasoning, which I have contended against from the onset here, or that of professionals who have been putting out very good, reliable, and sea worthy vessels for the JMSDF for decades. I know which side of that scale balance I put my bets on.

shen said:

now, the compromise adopted by the Japanese may be forgivable if they put FCS-3A on a 4000tonnes range cheap frigate. but the Akizuki is bigger, just as expensive and manpower intensive as the more capable European frigates. that is bad design.

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You keep saying this, and I have continued and will continue to refute it.

I know personally people who have worked with the Japanese. I have personally worked in that industry, leading a team that provided critical design functionality and efforts for the Virginia class submarines, as well as other naval projects.

As I have explained on this thread, for its weight, compared to other similar weight vessels, its capabilities are as strong or stronger.

You Shen are new to this forum. You have not given us any bonafides where from we can gauge you ability to reliably refute experts in the field who have spent decades designing very capable, very strong and reliable military vessels for the JMSDF. Have you done any such work professionally yourself?

As you said earlier, "we will have to agree to disagree," and until you provide a whole lot more props on why we should believe you over those people who do this for a living for the defense of their own nation, I know who I believe and put stock in, particularly when people I know personally who do this type of thing for a living come down heavily on the sides of the JMSDF designers and planners.

The Akizuki is an excellent design. It has outstanding capabilities. One need only look at it specs and its performance to date at sea to realize this. It will perform its mission very reliably and very capably...both in terms of ASW, AAW, and ASuW...and it will do it with a very well designed and capable combat management and sensor system that is the rival for its specific roles of any of the other strong systems available today.

Re: JMSDF Akizuki Class DDG (19DD AEGIS-like)

shen said:

...
X-band radar has better resolution, ideal for detection small targets like sea skimming missile, so it should be as high as possible to gain maximum radar horizon.
...

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shen, let me tease you: if an anti-ship missile was coming only five meters above the sea, wouldn't be advantageous to have the radar LOW on a ship's superstructure, not high as Sampon or APAR are installed?

Re: JMSDF Akizuki Class DDG (19DD AEGIS-like)

Jura said:

shen, or anybody, can you estimate what the difference would make placing the X-band antenna, say, 10 meters higher on a ship, with respect to the detection of a sea-skimming missile doing, say, 240 m/s? I of course assume the same radars and the trajectories of the same missiles and the answer would be, for example, "the detection at 25 instead of 20 kilometers"; if you don't want to post here, please email what you think to Krize1938_at sign_seznam.cz, thanks!

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There are radar horizon calculators available online that do a pretty decent job at these calculations, certainly good enough for these radar bands that we're talking about.

If we define "sea skimming" as missile flying 5 meters above water:

Antenna positioned 10 meters above water would be in a position to potentially detect the said missile at 22,2 km distance.

Antenna positioned 20 meters above water would do it at 27,6 km.

Antenna 20 m above water would do it at 31,8 km.

240 m/s is rather slow, though, even for a subsonic antiship missile. It's in tomahawk cruise missile class, speed wise.

One can roughly calculate that, IF the missile would go straight and not manouver, it would cover the said distances in 92 seconds, 116 seconds and 132 seconds, respectively. Missiles usually DO manouver and thus make their paths a bit longer and perhaps even slow themselves down slightly, right after a manouver, before picking their energy back up.

If one defined "sea skimming" as going 10 meters above water, then radar at 10 meters could potentially detect at 26,1 km, 20 meter radar at 31,5 km and 30 meter radar at 35,6 km.

Re: JMSDF Akizuki Class DDG (19DD AEGIS-like)

Totoro said:

There are radar horizon calculators available online that do a pretty decent job at these calculations, certainly good enough for these radar bands that we're talking about.

If we define "sea skimming" as missile flying 5 meters above water:

Antenna positioned 10 meters above water would be in a position to potentially detect the said missile at 22,2 km distance.

Antenna positioned 20 meters above water would do it at 27,6 km.

Antenna 20 m above water would do it at 31,8 km.

240 m/s is rather slow, though, even for a subsonic antiship missile. It's in tomahawk cruise missile class, speed wise.

One can roughly calculate that, IF the missile would go straight and not manouver, it would cover the said distances in 92 seconds, 116 seconds and 132 seconds, respectively. Missiles usually DO manouver and thus make their paths a bit longer and perhaps even slow themselves down slightly, right after a manouver, before picking their energy back up.

If one defined "sea skimming" as going 10 meters above water, then radar at 10 meters could potentially detect at 26,1 km, 20 meter radar at 31,5 km and 30 meter radar at 35,6 km.

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Thanks, Totoro!

Oh, had I entered "radar horizon calculator" into google

I picked the 240 m/s as the missile speed by checking the Harpoon on wikipedia ... it says: Speed 537 miles per hour (864 km/h)(240 m/s)
But I didn't have in mind any specific conflict, which would involve launching Harpoons against 19DD ... maybe subconsciously Clancy's Debt of Honor

Re: JMSDF Akizuki Class DDG (19DD AEGIS-like)

shen said:

ad hominem.

Please, Log in or Register to view URLs content!

" A: "All rodents are mammals, but a weasel isn't a rodent, so it can't be a mammal."
B: "I'm sorry, but I'd prefer to trust the opinion of a trained zoologist on this one."

B's argument is ad hominem: he is attempting to counter A not by addressing his argument, but by casting doubt on A's credentials. Note that B is polite and not at all insulting. "

address the argument, not the person please. stay on topic.

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LOL, nice link.

Re: JMSDF Akizuki Class DDG (19DD AEGIS-like)

Totoro said:

.............
If we define "sea skimming" as missile flying 5 meters above water:

Antenna positioned 10 meters above water would be in a position to potentially detect the said missile at 22,2 km distance.

Antenna positioned 20 meters above water would do it at 27,6 km.

Antenna 20 m above water would do it at 31,8 km.

...........................

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While your calculations are true , in real war scenario things would be much different . Side which would attempt to detect salvo of enemy ASMs with radars mounted on ship's masts would definitely lose badly . There is simply to little time between detecting , identifying and giving order to open fire on target (unless you want to open fire on anything that may resemble anti-ship missile ) .
Therefore , in real war , initial detection will be achieved with aerial assets . Even smaller navies employ helicopters equipped with radars and land-based patrol aircraft . They would be the eyes of the navy and their role would be among other things to spot incoming missiles .
When so warned , role of the ship's radars would be to acquire already detected target when it gets in their range , and then to guide ship's weapons on it . When you consider such scenario , height of the antenna on Akizuki is not that important - they would at least use their Seahawks with HPS-104 search radars to detect potential targets .

Re: JMSDF Akizuki Class DDG (19DD AEGIS-like)

shen said:

address the argument, not the person please. stay on topic.

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I did, hehehe, on both counts. You just did not like the way I did so. So, you gave a non-response. And that's fine. It's an open forum.

But for me as regards your arguments and continued statements regarding the Akisuki Class, it's simple.

No props...no chops.

But then, you already knew that, eh?

TerraN_EmpirE said:

Jeff I am not sure about those being F35Bs the craft on the deck clearly have folded wings and the take of looked like CATBAR which indicate F35C. .

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You're right. It is definitely a CATOBAR carrier and those would almost have to be F-35Cs lined up on the cats.

Jeff Head said:

Well, The other video at FORBIN's link is a shorter video showing some of the same, but the last shot of the Japanese carrier shows F-35Cs on what appears to be a JMSDF CATOBAR design.

Apparently all of this is a marketing campaign for some fictional book about such a confrontation. So, I do not believe ti can be construed as offical Japanese Defense/Government policy or strategy.

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It is not a fictional book but a magazine about the F-3, it has a DVD and the videos are taken from the DVD is not a official video, just a Magazine`s video and view

Makes sense, their is a booming Military Otaku community and Subculture in Japan and the Mitsubishi ATD-X program has to have some people hot and bothered.