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[WAD] The Swedish Visby-class "stealth" corvette

 
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[WAD] The Swedish Visby-class "stealth" corvette - 5/23/2020 3:36:52 PM   
Aaabcwea

 

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Hey! I'm relatively new to ASuW warfare and was wondering if anyone can explain to me.

The Visby has an in-simulation radar detection range (against other surface ships) of only 16.6 M. In order words, the horizon, not over-the-horizon (OTH). However, the surface sensors ring shows 22.5 M and the database says the radars have ranges of 80 M, 48 M, and 25 M. What is going on, why is everything inconsistent??? It also does not appear to match reality! The Visby’s in-simulation “stealth” is also quite questionable. Against a Russian destroyer radar, the Visby is detected at 80% of the range of corvettes with hundreds of times greater radar cross sections. Set the Visby and the Göteborg up against the Sovremenny and the Göteborg is detected at 100 M and the Visby at 80 M. In conclusion, the Visby cannot see anything beyond the horizon, anything that appears on the horizon can instantly detect it, and OTH it is detected at twice the range it detects anything using its Seawatch, which is its only OTH!

In reality, I believe it uses a Pilot Mk.3 that is X-band, not I-band, and not the Pilot Mk.2 (1992) or Pilot Mk.1 (1988). Detailed specs of the Pilot Mk.3 are available. I do not know how to get the range using the specs but maybe anyone does? The Sea Giraffe AMB (not called “3D” AFAIK) has a range of 97 M, sources say. I do not know the range of the CEROS 200, which is actually a stealth version. Sources say the Visby is detectable at 30% of the range of other ships, probably corvettes. Another quite major correction is that the Visby does not have a Missile Defence of 4, which makes the AI waste missiles against it, it is “Hydra TAS”, and height is 72.8.

The Visby in Command it seems is not even close to reality. Am I missing anything?

< Message edited by Dimitris -- 5/25/2020 7:46:00 AM >
Post #: 1
RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 4:22:43 PM   
thewood1

 

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You're missing the thread for db and unit issues. Its in the mods area. It'll be better handled there.

< Message edited by thewood1 -- 5/23/2020 6:26:31 PM >

(in reply to Aaabcwea)
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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 4:42:58 PM   
Rain08

 

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quote:

ORIGINAL: Aaabcwea

In reality, I believe it uses a Pilot Mk.3 that is X-band, not I-band, and not the Pilot Mk.2 (1992) or Pilot Mk.1 (1988). Detailed specs of the Pilot Mk.3 are available.


I'm assuming this is the RB 15 AShM? The frequency bands are displayed in NATO classification, rather than IEEE.




Attachment (1)

< Message edited by Rain08 -- 5/23/2020 4:43:20 PM >

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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 5:15:41 PM   
KLAB

 

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Joined: 2/27/2007
Status: online
https://www.matrixgames.com/forums/tm.asp?m=3436106

Post query in this forum and provide evidential links,For example a credible governmental report or verified manufacturer data on RCS etc.
Or it could be the DB editors have already done extensive research and "stealthy" is always an ill-defined subjective term given different radar frequencies and there relative strengths and weaknesses.

Hope this helps?
K

(in reply to Rain08)
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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 6:26:59 PM   
Zanthra

 

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Another thing to consider is that because of the horizon, stealth or no stealth, a surface ship can only see you on radar if you are really close (OTH radars are generally low frequency and very high power, so stealth is of relatively little use), and that means stealth does not help much. Check the difference in the distance of detection against an MPA like a P-8 at much longer range than a surface ship.

< Message edited by Zanthra -- 5/23/2020 6:29:15 PM >

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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 7:38:59 PM   
Aaabcwea

 

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The whole point of the Visby is being able to detect threats before it is detected and today that's not possible under any circumstance other than if the enemy is not radiating!

quote:

ORIGINAL: Rain08

quote:

ORIGINAL: Aaabcwea

In reality, I believe it uses a Pilot Mk.3 that is X-band, not I-band, and not the Pilot Mk.2 (1992) or Pilot Mk.1 (1988). Detailed specs of the Pilot Mk.3 are available.


I'm assuming this is the RB 15 AShM? The frequency bands are displayed in NATO classification, rather than IEEE.



Thank you, I obviously confused the classification systems.

quote:

ORIGINAL: KLAB

Post query in this forum and provide evidential links,For example a credible governmental report or verified manufacturer data on RCS etc.
Or it could be the DB editors have already done extensive research and "stealthy" is always an ill-defined subjective term given different radar frequencies and there relative strengths and weaknesses.

Hope this helps?
K


I will check it out in the morning! I believe I have adequate sources for at least a few corrections, not including the RCS.

quote:

ORIGINAL: Zanthra

Another thing to consider is that because of the horizon, stealth or no stealth, a surface ship can only see you on radar if you are really close (OTH radars are generally low frequency and very high power, so stealth is of relatively little use), and that means stealth does not help much. Check the difference in the distance of detection against an MPA like a P-8 at much longer range than a surface ship.


Thank you, I will continue searching for circumstances in which the Visby is superior to other corvettes. Indeed, surface stealth appears quite the paradox to me since anything can see you instantly under the horizon and OTH stealthing is ineffective. This is another reason why the Visby cannot be as ineffective as it is in Command. If it was that ineffective, why use stealthing? Sources say stealthing it made it cost twice as much and Sweden is not abandoning them. I have yet to see the effect against any non-surface radar, maybe there are significant advantages. Today, the only advantages of the Visby against other corvettes I have discovered is its low-probability-of-intercept radar, which stops identification, and the short OODA (10 seconds) its modelled with for whatever reason.

< Message edited by Aaabcwea -- 5/23/2020 7:41:01 PM >

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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 8:16:29 PM   
Dimitris


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Hello and welcome.

quote:

ORIGINAL: Aaabcwea
The Visby has an in-simulation radar detection range (against other surface ships) of only 16.6 M. In order words, the horizon, not over-the-horizon (OTH). However, the surface sensors ring shows 22.5 M and the database says the radars have ranges of 80 M, 48 M, and 25 M. What is going on, why is everything inconsistent???

The radars are realistically limited by the radar horizon. However, there is also the factor of mast-height (plus surface ducting, if the sea is calm enough). The nominal ranges of the radars can still be useful; for example, surface-search radars can sometimes spot low-altitude air/missile contacts. Also, if the mast-height value changes in the DB (e.g. a correction from fresh data or future upgrade) then the sensor range will benefit from this increased horizon value.


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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 8:26:49 PM   
Dimitris


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quote:

ORIGINAL: Aaabcwea
The whole point of the Visby is being able to detect threats before it is detected and today that's not possible under any circumstance other than if the enemy is not radiating!


Visby was designed to be quite low-observable on radar, that is true. That doesn't mean it cannot be detected from close enough. Like with aircraft, stealth is not an invisibility cloak.

Visby's low RCS is most helpful against airborne high-frequency radar systems, which are the primary surveillance threat against ships because of their massively larger horizon. Try this test: Place a Visby and a non-stealthy corvette at equal distance from e.g. a Tu-95RT or E-3 or P-3 radiating, and gradually move the aircraft towards them. See who gets detected at what range.

Against lower-frequency sets (like most OTH radars) the Visby has a much higher RCS because of the Raleigh/resonance scattering effects, and thus can be detected at larger distances.

< Message edited by Dimitris -- 5/23/2020 8:29:39 PM >


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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 8:43:26 PM   
Zanthra

 

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Joined: 2/6/2019
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quote:

ORIGINAL: Dimitris
...
Visby's low RCS is most helpful against airborne high-frequency radar systems, which are the primary surveillance threat against ships because of their massively larger horizon. Try this test: Place a Visby and a non-stealthy corvette at equal distance from e.g. a Tu-95RT or E-3 or P-3 radiating, and gradually move the aircraft towards them. See who gets detected at what range.
...


Make sure you have the radars on the ships off, or in the editor delete or damage the ELINT on the aircraft, since if it has radar active, they will be detected as ESM contacts at a longer range than radar contacts.


< Message edited by Zanthra -- 5/23/2020 8:44:21 PM >

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RE: The Swedish Visby-class "stealth" corvette - 5/23/2020 9:52:37 PM   
giantsquid

 

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From: Milan, Italy
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Thank you Dimitris, very clear explanation.
I remember i run similar tests month ago and the Visby performed nicely

Francesco

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RE: The Swedish Visby-class "stealth" corvette - 5/26/2020 4:04:20 PM   
Aaabcwea

 

Posts: 10
Joined: 5/23/2020
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quote:

ORIGINAL: Dimitris

Hello and welcome.

quote:

ORIGINAL: Aaabcwea
The Visby has an in-simulation radar detection range (against other surface ships) of only 16.6 M. In order words, the horizon, not over-the-horizon (OTH). However, the surface sensors ring shows 22.5 M and the database says the radars have ranges of 80 M, 48 M, and 25 M. What is going on, why is everything inconsistent???

The radars are realistically limited by the radar horizon. However, there is also the factor of mast-height (plus surface ducting, if the sea is calm enough). The nominal ranges of the radars can still be useful; for example, surface-search radars can sometimes spot low-altitude air/missile contacts. Also, if the mast-height value changes in the DB (e.g. a correction from fresh data or future upgrade) then the sensor range will benefit from this increased horizon value.



The "height" of all ships in the database appears to be "0 m", is that a bug? If I knew the heights, I could calculate the horizons in an attempt to more accurately predict detection ranges, which is still difficult.

(in reply to Dimitris)
Post #: 11
RE: The Swedish Visby-class "stealth" corvette - 5/30/2020 3:56:11 PM   
Aaabcwea

 

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Joined: 5/23/2020
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Apparently, the height appearing as 0 m in the database is not a bug... the database is simply missing a lot of height data? Is a default height assumed based on class?

(in reply to Aaabcwea)
Post #: 12
RE: The Swedish Visby-class "stealth" corvette - 6/1/2020 12:15:11 PM   
Dimitris


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The sensor height is not dictated by the ship height value, but by the "mast height" value. (Many ships have fairly low superstructure profile, but elevated main sensor masts). This is not currently displayed in the DB viewer, but you can see if you browse the DB with an external tool.

That said, I'm not sure I understand what you are trying to do. Let's say you determine that mast height X gives you a warning time of Y, and X2 gives you Y2. Great. Then...? By itself, that information does not give you a lot. You will still have to experiment with different formations against an assumed air/missile attack to see how your planned group fares - with or without the warning time at hand.

My overall advice would be: Don't try to dive too deep into the math. Play the game, not the numbers. When you lose, it's rarely because e.g. sensor-X made a detection at 15nm instead of the 20nm you expected. The important mistakes usually happen far higher in the command level.

(EDIT: If, OTOH, you are doing serious system analysis, which definitely merits measuring every centimeter of extra mast height, please contact us privately about Command-PE)

Cheers.

< Message edited by Dimitris -- 6/1/2020 12:43:55 PM >


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