[WAD] B446: Passive sonar not detecting an Alfa at 24 knots

[Der Zeitgeist]

There seems to be something wrong either with towed array sonars or the noise levels of submarines are way off.
The test scenario is attached.
A Perry-class frigate creeping at 5 knots to maximise passive sonar performance, being overtaken by an Alfa at about 25 knots, just below cavitation speed. The sub is above the layer. Detection only occurs at about 3 miles, well inside torpedo range.

[mikmykWS]

concur. Stay tuned.

[CapnDarwin]

Is the Alfa in your baffles and above the layer? If so your towed array is below and will have reduced effectiveness against the sub and if he is in behind you your hull mount arrays are blind. I also don't know the year of the scenario. Pre 84 the Soviet subs were loud with poorly machined props and after 84 they all got a lot quieter. I don't know if that is in the database either.

[mikmykWS]

Yes that is exactly what is is.

Going to spike my coffee..

M

[mikmykWS]

Looks like something with dual mode sonar though. Stay tuned.

[Der Zeitgeist]

I just did some further tests, trying to use different bearings and depths (above and below the layer). In some cases, I was able to detect the Alfa at 16 miles, don't know what range would actually be realistic.

[joey]

Alphas were very loud compared to other Soviet and US submarines. In many cases it did not matter much if they were above or below the layer. They were just loud. Other soviet subs might be detected at 5 to 8 miles. Alphas five times that amount might be possible.

[Dimitris]

Jim's hunch was correct. The Alfa happened to be in the "gap" between far and deep (vulnerable to CZ pickup by towed array) and up close (vulnerable to direct path from either the TA or the hull-mounted sonar).

Looking now at possible issue with active-passive sonar.

[Der Zeitgeist]

Great, thanks for looking into it![:)]

[Dimitris]

No dual-mode issue. Sonars work as expected.

[Der Zeitgeist]

ORIGINAL: Sunburn

No dual-mode issue. Sonars work as expected.

Oh well, guess those subs are just supposed to be sneaky, then. [:)]

[Der Zeitgeist]

ORIGINAL: Capn Darwin

Is the Alfa in your baffles and above the layer? If so your towed array is below and will have reduced effectiveness against the sub and if he is in behind you your hull mount arrays are blind. I also don't know the year of the scenario. Pre 84 the Soviet subs were loud with poorly machined props and after 84 they all got a lot quieter. I don't know if that is in the database either.

Another question for the developers: Are towed arrays and variable depth sonars always streamed below the layer in the game? If not, how do we know at what depth the array is currently sitting?

[Dimitris]

Yes, they are assumed to be always streamed just under the layer, in the middle of the deep sound channel. This maximizes their effectiveness against submarines under the layer.