Interesting. We can live with it if we considere the irregular values in bold as random atmospheric events.

I just played my first scenarios with the Westpac battleset and the new radar model got me by surprise, enough to have me return to this EW topic. Though I've read Brad's AEW&C / AWACS performance testing some time ago, I must have been holding onto some Sauronistic faith of the "all seeing eye".

So I went back to Red Flag for testing.
Westpac E2C AEW ranges vs. surface combatants:

Shocking. A Dergach can get a cheap shot with it's Sunburn missiles and even the Hawkeye will not detect it (before firing), shipborne radars are even worse off.
38nm really? Any views? Understandably there is not much data around but for example "The Naval Institute Guide to World Naval Weapons Systems, 1997-1998" has that the "APS-138 can reportedly track a cruise missile at a range of 150nm". The Dergach is small ship, but it's still 200 feet of metal. And the Group II has the APS-145, digital and all. 38? Need to rethink carrier defense.

What do you do to protect your ships from missile boats?

The new AESA radars are also cut to size by RCS:
Westpac APG-81 AESA ranges vs. surface ships

No bonus for the AESA. The Dergach might get a visual sooner than radar detection.

 

I just played my first scenarios with the Westpac battleset and the new radar model got me by surprise, enough to have me return to this EW topic. Though I've read Brad's AEW&C / AWACS performance testing some time ago, I must have been holding onto some Sauronistic faith of the "all seeing eye".

Dergach doesn't look particularly stealthy to me. Methinks you have the beginnings of a case to modify a lot of ship RCS values in the database. You've shown a few examples of perhaps too short detection ranges. At what range do you expect detection of those platforms? Is there a general pattern across all ships (or within one or more types of ships) that would be handy for Brad (i.e. all Frigates need their RCS values increased by 4)?

The RCS values are mostly guesswork based on comparisons with the size, length, shape and stealth features (if any) of other ships. This is probably just one that needs adjustment.

... At what range do you expect detection of those platforms? ...

 

Tough question, as my expectations are based on the legacy battlesets and not much more. My gut feeling was "more than 100nm", but I'd search for data first. I found just one useful looking source (referenced many places), an RCS Ship Table at: www.mar-it.de itself based on "Williams/Cramp/Curtis: Experimental study of the radar cross section of maritime targets, 1978".

(Are you aware of any other source for experimental RCS values?)

 

This table lists a good range of commercial vessels and one "warship". Apparently "warship" has higher relative RCS (lot of masts, turrets, etc., reasonable) and the other difference that warships are rated by "displacement" while commercial ships use "gross tonnage" (good reading this one), no conversion, great .

Still length can be used to correlate these values to ours I guess.

Fit a function to it and take a closer look at the DB where there is extreme deviation vs DB RCS.

 

After some crunching and guessing and cleaning the base table is this:

 

t.b.cont.

 

These are all factors already in play for determining the RCS value to be used.

 

At the rate which platforms were added, however, there has no doubt been some degradation of the accuracy of the relative values. Again, its very much relative. Because two "warships" are no more equal than two "container ships".

 

As for AESA and other peculiarities, keep in mind that we have a single radar model. There is no accounting for monopulse, pulse Doppler, synthetic aperture, etc, etc. Their range values are drawn from H4 values where possible, and if not, then extrapolated or drawn from other sources.

At the rate which platforms were added, however, there has no doubt been some degradation of the accuracy of the relative values. Again, its very much relative. Because two "warships" are no more equal than two "container ships".

True I'm aware, and without actual facts I can only data mine the DB for relative mismatches, but even the out of place values might just mean that that ship is special.

Ok, before I waste any more time would you check these if this adds any value:

I looked at ships grouped by subtype (CV,CG,DD,FF,PT,...) hoping that there is more RCS correlation among similar purpose vessels. Started with Frigates, sorted them by length and looked for out of series RCS values. Then checked the DB description for any mention of stealth.

The first nuggets:

"RCS" is the RCS from the DB

"RCS by Len" is the avarage RCS of similar length ships.

 

Is any of these a valid correction?

I think ship's RCS must at least be considered basically as function of lenght, wide and height (as HCE models not the different angles of radar incidence against the radar target, i.e., frontal or lateral at least). I use lenght x wide halved, plus height.

 

Edited: and later I use a table, of course. And as ship's height is a value usually not reflected on books, I use the generic height values of 19, 29 and 40 meters employed in the DB.

About modelling AESA and PESA radars an idea can come from this:

- PESA radars increased his range some 50% in relation with a conventional radar of the same power.

- AESA radars increased his range some 100% in relation with a conventional radar of the same power.

 

Edited:

But those increased radars ranges are implemented in the radar ranges reflected on the DB, the "increased PESA/AESA range" would be a plus on those previous ranges.

And yes, me too for years was thinking a "warship" has a greater RCS than a tonnage equivalent civilian warship, with a lot of radar antennas, turrets, weapons mounts and other things (and what about an aircraft carrier with the deck full of planes ?!).

Also, in the DBs aircrafts I add some penalty when the plane is equipped with search radars (+1, example, fighter search radar) or big search radars (+2, example, AWACS radar).

 

Edited: also, a ship with high "sides" or boards (example: oiler, merchant, civilian passenger cruise ship) must have a higher radar return.

I like the idea of a Iranian PG Toragh/Boghammar with the correspondent "inshore fishing vessel" 142 RCS as reflected on the tables ("inshore fishing vessel" is almost the same size than PG Toragh), as opposite to the current 165 RCS, perhaps it's a solution to how to sneak with a small size boat near a conventional warship (but a think it requires a lot of testing).

 

Edited: also, a small boat gets more "cover" from sea's radar return clutter, more if tthe radar is tuned to bigger targets to avoid false returns because sea state.

Keep going guys, looking good so far. Brad is away for a week or so and may not be on the forum but I'm sure he'll jump back in when he returns.

 

I don't agree with the 142 RCS for a Boghammer (a max detect range of 9nm when using a 360nm ranged radar) but I appreciate the arguments.

 

In the Boghammer case I would look at vessels or sensors likely to be facing off against the Boghammer, then come up with a reasonable detection range, then work the RCS backwards from that. A starting place perhaps anyway.

Just to add some humour, and illustrate some problems in getting it perfect, I remember one time picking up three contacts very close to each other but some distance away, turned out to be a super tanker

Great, Don!

And don't forget:

- Máximum surface-to-surface radar range is 25-27 nm, because the radar horizon (remember, Earth is sphere-shaped ).

- If you active surface-to-surface radar, you will be picked by enemy ESM and fired upon! (as very usual case, the USSR/Russia Komar and Osa patrol missile boats are equipped with ESM, but not the export versions).