PLAN Anti-ship/surface missiles

Totoro said:

Are you guys talking about the same LRASM as mentioned here?

Please, Log in or Register to view URLs content!

contract volumes for various fiscal years throughout its lifetime so far are not very high at all.

Click to expand...

Yes, that is the same LRASM. It shows 99 missiles in total so far. I mentioned a figure of 100.
Plus the US is buying 48 per year starting in 2021.

For the next 5 years, I reckon they are the ONLY option available to the USA for a long-range antiship missile.
So the US military has no choice to buy them.
But they are only buying small quantities, so that is part of the reason why I think LRASMs aren't that useful.

@Gloire_bb

I have no idea where you got the idea that there are a thousand LRASMs.

nlalyst said:

All i found was a photo of a power point slide. The beam-width is particularly unconvincing. A much larger P-18 radar has a beamwidth of 6 degrees:

Please, Log in or Register to view URLs content!

You cannot magically convert a 2D early warning radar into a targeting radar through a software update.

Click to expand...

The P-18 uses vacuum tubes for goodness sake.

When you have digital electronics and a precise clock, accuracy improves tremendously.

I think we'll just have to agree to disagree on this one

Accuracy can be improved with digital post processing. However, to reduce the beamwidth you need to overhaul the entire front-end of the radar. The Type 517 "brochure" that's linked on Wikipedia has just 2 rows of 2 Yagi-Uda antennas and a claimed beamwidth of 5 degrees. The much larger JY-27 has a beamwidth of 7 degrees. That's an obvious red flag.

There are two ways to narrow the beamwidth: stack more elements on the Yagi-Uda, which makes it longer. Stack the Yagi-Udas either horizontally or vertically, or both. The latter is which most of the very capable VHF radars do, because that also happens to be the more practical solution.

Finally, VHF radars are known to have issues with high speed low altitude targets. Incidentally, the JY-27 radar was destroyed by IAF in Syria in 2019. Possibly by a low flying F-16, although no confirmation was given by IAF.

nlalyst said:

Accuracy can be improved with digital post processing. However, to reduce the beamwidth you need to overhaul the entire front-end of the radar. The Type 517 "brochure" that's linked on Wikipedia has just 2 rows of 2 Yagi-Uda antennas and a claimed beamwidth of 5 degrees. The much larger JY-27 has a beamwidth of 7 degrees. That's an obvious red flag.

There are two ways to narrow the beamwidth: stack more elements on the Yagi-Uda, which makes it longer. Stack the Yagi-Udas either horizontally or vertically, or both. The latter is which most of the very capable VHF radars do, because that also happens to be the more practical solution.

Finally, VHF radars are known to have issues with high speed low altitude targets. Incidentally, the JY-27 radar was destroyed by IAF in Syria in 2019. Possibly by a low flying F-16, although no confirmation was given by IAF.

Click to expand...

That's true VHF radars have issues with low flying aircraft but that was settled with MTI with Doppler filtering. Best case of a VHF radar dealing with an antiship missile in a true hostile condition was the HMS Sheffield.

The HMS Sheffield uses a VHF search radar called the Type 965. We can use Wiki for this.



The Sheffield did not pick up the Super Etendards at 30m but the Type 965 radar did pick them up when they pop up at 37 meters. The rest is a failure of leadership, lack of proper IFF, ECM and CIWS. This radar did not have MTI/MTD and Doppler Filtering until in later editions. Even early SPY-1 has issues with sea skimmers until MTI and Doppler Filtering was introduced. (MTD = MTI with monopulse and fully coherent processing).

That's the Type 965 radar there on the HMS Sheffield after her fateful moment.



The Type 517M radar on the 052D doesn't work in isolation. Its backed by other radars, most notably the Type 364 (SR64 export name) radar. This radar features Pulse Compression and AMTD with the ability to pick up targets < 1m2 RCS and up to Mach 3.



With the Type 364/SR64 located right here for maximum radar horizon:


JY-27 in Syria could be the result of Syrian poor defenses. Meaning the F-16 could still be detected but the Syrians didn't have the air defense [or the competence] to shoot it down. Nonetheless, the radar was up the next day, which makes me suspect this might have been a dummy.

Tam said:

That's true VHF radars have issues with low flying aircraft but that was settled with MTI with Doppler filtering. Best case of a VHF radar dealing with an antiship missile in a true hostile condition was the HMS Sheffield.

Click to expand...

Has it? It keeps coming up, even in rather recent publications. It was specifically mentioned as negative for the Type 517 radar by Friedman in his 2006 publication.

Much more recently, from a John Hopkins University APL lab 2020 publication, on the Chinese SIAR radar on Subi Reef:

There are claims that this Chinese SIAR also has a “low-altitude capability.” If true, an ability to overcome ground clutter to track low-flying targets would certainly make it unique among VHF-band radars.

Click to expand...

I think you will enjoy reading the original publication. The author analyzes the Chinese claim that this VHF radar can produce a targeting solution against a VLO aircraft. Again refering to the downsides of VHF:

Chinese researchers claim to have solved many of the problems associated with conventional VHF radar using SIAR and its inherent multiple-input, multiple-output (MIMO) techniques. VHF-band radar typically suffer from ground clutter, multipath interference, poor angular resolution, and an inability to reliably determine target elevation.While a VHF radar may detect the presence of low-observable aircraft in a general direction, the nature of VHF propagation means that conventional radars operating at these lower frequencies cannot accurately track stealth aircraft, let alone target them with a weapon such as a SAM.

Click to expand...

Source:

nlalyst said:

Has it? It keeps coming up, even in rather recent publications. It was specifically mentioned as negative for the Type 517 radar by Friedman in his 2006 publication.

Much more recently, from a John Hopkins University APL lab 2020 publication, on the Chinese SIAR radar on Subi Reef:

I think you will enjoy reading the original publication. The author analyzes the Chinese claim that this VHF radar can produce a targeting solution against a VLO aircraft. Again refering to the downsides of VHF:

Source:

Please, Log in or Register to view URLs content!

Click to expand...

I am not saying that it can be used for targeting solution. Far from it. The purpose of the VHF radars is to queue other higher frequency radars to the object. In this case for the 052D, the Type 517 would queue the Type 346 and Type 364 radars to the direction of the target, greatly reducing the search area needed for the other two radars.

As for Friedman and based on your previous description that you think the 517 array is ---

The Type 517 "brochure" that's linked on Wikipedia has just 2 rows of 2 Yagi-Uda antennas and a claimed beamwidth of 5 degrees.

Click to expand...

You can visually see that from every picture of the 052C/D, its two rows of four Yagi Uda antennas, and the Yagis themselves have a different design from the previous. 2006? Did he ever account for the revised version of the 517 that appeared in the 052C, or is he referring to the 517 that was on the Luda? The export version of the 517 consists of two rows with six Yagi antennas, with the spacing closer between the antennas.

Also I'm going to add that the wiki you picked mentioned the radar having MTD.

• • Non-coherent pulse compression (NCPC) system
  • Moving target automatically detection
  • Long range air surveillance

This seems to be a different model of the 517 with the NCPC with only a 2x4 array, used with the Ludas. The one below has coherent pulse compression and uses a 2 x 6 array and is used with the F22P.

Tam said:

As for Friedman and based on your previous description that you think the 517 array is ---


You can visually see that from every picture of the 052C/D, its two rows of four Yagi Uda antennas, and the Yagis themselves have a different design from the previous. 2006? Did he ever account for the revised version of the 517 that appeared in the 052C, or is he referring to the 517 that was on the Luda? The export version of the 517 consists of two rows with six Yagi antennas, with the spacing closer between the antennas.

Click to expand...

I was talking about the slide from the Wikipedia page reference:

Two Yagi-Uda per row, yet a beamwidth of 5 degrees horizontally which is an obvious red flag, as even much larger VHF radars with many more staked Yagi-Uda antenna don't have beamwidths that narrow.

Friedman acknowledges that the Type 052C has an updated antenna, but does not provide any additional information other than it being VHF and that the initial version on older ships (with 2 antennas per row) resembles the Soviet Knife Rest radar, although with a somewhat longer Yagi-Uda.

For example, here is a very long high-gain Yagi-Uda antenna for aicraft tracking with 15 elements. I counted 14 elements on the Type 517

It has a beamwidth of 30 degrees. If you stack two of these antenna in a row, at best you can halve the beamwidth (at a cost of noticeable sidelobes), so still a 15 degrees wide beam.

Ran out of time: if you look a bit below in the link I sent, there is a plot of what the beamwidth is for a stack of 4 antennas (like on Type 052C): it comes to about 6.5 degrees at 3dB. But the sidelobes are rather strong. This can be reduced by stacking the Yagis closer together, at a cost in gain and main beamwidth.

HD-1, HD-1A, launch platforms. The last image is from the 2018 Zhuhai show. Interestingly, in the image, the third missile from the foreground appears to show "HD-1C". If true, this would be a new variant. Unfortunately, I couldn't find any information about it.