A question about the Dutch navy frigate Kortenaer-class.

[PreMars]

I read in the book Jane's Fighting Ships 1989-90 that the Kortenaer-class frigates are equipped with STIR-180 radar and WM-25 radar. It seems that both radars can be used for fire control of Sea Sparrow missiles and main guns, so what is the difference in the functions of these two radars on the ship?

 

[perttime]

As far as I can find out... WM-25 is a Fire Control System that includes a couple of radars for searching, tracking and illuminating targets. STIR is an additional "Separate Target Illumination Radar (STIR)"

 

[Arjen]

Deugdelijke Schepen - Marinescheepsbouw 1945-1995 by S.G. Nooteboom says all of them - one WM-25, three STIRs for each ship - are for Fire Control. Two STIRs dedicated to the ship's Standard missiles, one to NATO-Seasparrow.

The description of STIR by @perttime is the same one Nooteboom gives.

 

[TomS]

So, the WM25 "ball" has two separate antennas, one for low-altitude air and surface search (the bottom half), the other (the top half) for fire control.



The STIR is essentially the top half of a WM25 with more power and a larger antenna. Which means the STIR has more range but needs to be cued onto its target by another radar, while the WM25 has less range but is more self-contained. The WM25 is also used for gun fire control, while the STIRs are exclusively for missiles.

Edit: the WM25 is basically the same as the CAS portion of the Mk92 fire control in the FFG-7 class.

 

[Hobbes]

Deugdelijke Schepen - Marinescheepsbouw 1945-1995 by S.G. Nooteboom says all of them - one WM-25, three STIRs for each ship - are for Fire Control. Two STIRs dedicated to the ship's Standard missiles, one to NATO-Seasparrow.

The description of STIR by @perttime is the same one Nooteboom gives.

The 3 STIR fit was only for the van Heemskerk class, an air defence version of the Kortenaers.

Kortenaer: Sea Sparrow only, with one STIR, van Heemskerk: Sea Sparrow plus Standard, with 3 STIR (2x STIR 240, 1x STIR 180, IIRC).

 

[Arjen]

@Hobbes I should have read Nooteboom better, you are quite right.
Chapter 9 deals with both classes, I picked the wrong page. Standard should have been my clue.

 

[PreMars]

So, the WM25 "ball" has two separate antennas, one for low-altitude air and surface search (the bottom half), the other (the top half) for fire control.

View attachment 733907

The STIR is essentially the top half of a WM25 with more power and a larger antenna. Which means the STIR has more range but needs to be cued onto its target by another radar, while the WM25 has less range but is more self-contained. The WM25 is also used for gun fire control, while the STIRs are exclusively for missiles.

Edit: the WM25 is basically the same as the CAS portion of the Mk92 fire control in the FFG-7 class.

So what is the entire air defense warfare process?
The LW-08 is a 2D-radar and it has to give the target information to whom?
The process is LW-08→WM-25→STIR, or LW-08→STIR and LW-08→WM-25 separately?

 

[TomS]

So what is the entire air defense warfare process?
The LW-08 is a 2D-radar and it has to give the target information to whom?
The process is LW-08→WM-25→STIR, or LW-08→STIR and LW-08→WM-25 separately?

Data flows from LW-08 and the WM-25 search radar (and ZW-06 surface search) into the SEWACO II combat management system (CMS). Then target cueing info flows to the STIR, which also probably sends back tracking and elevation data into the CMS.

For gun engagements the WM-25 can probably pass track data from the search antenna to the track antenna on its own console and use that to aim the gun, but it should be talking to the CMS as well.

 

[PreMars]

Data flows from LW-08 and the WM-25 search radar (and ZW-06 surface search) into the SEWACO II combat management system (CMS). Then target cueing info flows to the STIR, which also probably sends back tracking and elevation data into the CMS.

For gun engagements the WM-25 can probably pass track data from the search antenna to the track antenna on its own console and use that to aim the gun, but it should be talking to the CMS as well.

Helpful answer. Thanks!

 

[PreMars]

Data flows from LW-08 and the WM-25 search radar (and ZW-06 surface search) into the SEWACO II combat management system (CMS). Then target cueing info flows to the STIR, which also probably sends back tracking and elevation data into the CMS.

For gun engagements the WM-25 can probably pass track data from the search antenna to the track antenna on its own console and use that to aim the gun, but it should be talking to the CMS as well.

Another question: is it true that ZW-06 is not as important as WM-25 in detecting air targets?
Friedman's book Naval Radar says ZW-06 can detect targets at 20000ft. So what makes WM-25 irreplacable? Is the higher data update rate of WM-25?