Victor III v Perry Class

[kcdusk]

One of Russias first nuclear submarines, a Victor III, is 23.0 nautical miles behind an American Perry class surface ship. The range of 23 miles is the outer range that the stationary Victor can detect the Perry which is travelling at 20 knots. The chance is 25% and detection is made.

 

The Victor dives below the layer and increases speed to 30kts. While travelling at this speed the Victor is blind to the Perrys movements. The Victor decides to travel at 30kts for 1 hour before slowing to 5kts, coming above the layer and checking the position hoping to find himself about 13 miles behind the Perry if her speed and course remains unchanged.

 

The Perry continues on its speed and course for 57 minutes, when she slows to 15 kts and changes course to be heading back towards the Victor. At this time the range is 13.0nm however the situation the Victor was expecting to find is much different, with the Perry now heading towards him …

 

The detection game begins again at 13nm, and combatants unknowingly closing on each other.

 

0:00 Range 13.0nm. Perry unable to detect. Victor passive sonar (25%) fails.

 

0:03 Range 12.0nm. Perry unable to detect. Victor (25%) fails.

 

0:06 Range 11.0nm Perry unable to detect. Victor (50%) fails.

 

0:09 Range 10.0nm Perry unable to detect. Victor (50%) fails.

 

0:12 Range 9.0nm Perry unable to detect. Victor (50%) fails.

 

0:15 Range 8.0nm Perry unable to detect. Victor (50%) fails.

 

0:18 Range 7.0nm Perry unable to detect. Victor (50%) Success for bearing and type (surface contact). Classification (35%) no data.

 

0:21 Range 6.0nm. Perry (random movement called for) slows and starts to deploy towed sonar (assume experimental towed passive sonar on the Perry). It takes 21 minutes to deploy. Perry slows to 5kts while deploying sonar.

 

Victor continues at 5kts trying to get better resolution.

 

During detection the Perry still has no chance of detecting the Victor (max range is 2.25nm). The Victor has a 25% chance due to slower speed of Perry, with a +15% for maintaining detection (looses contact).

 

0:28 Range 5.5nm. Victor fails detection.

 

0:31 Range 5.0nm. Victor has 50% + 15% to gain contact, success. Classification 35% (no data).

 

0:34 Range 4.5nm. Victor 65% maintain contact, fails.

 

0:37 Range 4.0nm. Victor 65%, contact made, classification: exact, classified as Perry.

 

0:40 Range 3.5nm. Victor decides to fire 2 torpedoes. 1 set at fast (8.3nm/40kts), 1 set at slow (13.5/24). At this point the Victor does not know range to the target.

 

Victor looses contact. Perry 25% to detect Victor (fail), torpedo fired detection (fail).

 

0:43 Range 3.0nm to Victor/1.25nm to fast torp/2.0 to slow torp. Perry towed sonar is deployed does not detect anything. Victor regains contact.

 

0:46 Range 2.5/torpedo at target/0.5nm.

 

Fast torpedo reaches the Perry without detection meaning NO countermeasures are deployed. 2G torpedo without wire guidance has 60% chance of hitting, misses.

 

 

0:49 Range 2.0nm/2nd torpedo reaches Perry.

 

Victor slips beneath the layer. Perry makes evasive manoeuvrer with towed sonar still deployed (increases speed to 25kts, Changes course 90 degrees). Torpedo has 23% chance of hitting and misses.

 

 

0:52 Range 3.5nm.

 

Perry continues at 25kts to vacate the area. Victor cruses at 5kts trying to maintain contact.

 

 

Perry is blind. Victor 90% chance and maintains contact. Fires 2 x fast torpedoes (40kts).

 

 

0:55 Range 5.0nm/3.0nmx2

 

Perry 25kts.

 

Victor maintains contact.

 

Torp 1 & 2 40kts. 2.0nm travelled

 

 

0:58 Torpedo range 2.5nm, 4.0nm travelled.

 

 

0:61 2.0nm, 6.0nm travelled

 

 

0:64 1.5nm, 8.3nm travelled and range reached. Torpedoes end route.

 

 

The Perry continues out of the area. Victor continues to crawl along at slow speed. I have not done any work with helecopters. The Perrys helectoper and sonar bouys would likely add to the encounter.

 

 

 

Observations and comments

Submarines moving slowly with anechoic coating are very difficult to detect until very short ranges. Even at long range where there is a low (25%) chance of detection, the maximum range of detection is often under 2 nautical miles (again, LONG range).

 

 

Submarines detecting a surface contact with passive sonar do not know the range to the surface contact, making choosing to set torpedoes at high speed (short range) or low speed (long range) a critical tactical decision.

 

 

Ships can outrun or at least outlast a pursuing torpedo if they detect it in time.

 

 

Ships under fire from submarine torpedoes should increase speed to 25+kts & change direction to perform an evasive manoeuvre which reduces the torpedo hit chance. At that speed, the ship is blind to detecting passively or actively the submarine which has fired. The ship should look to exit the area at high speed before returning at slow speed to search the area for the submarine (effectively re-setting the game).

 

 

Knowing how far to run at high speed, when to reduce speed and return to search the area is a crap shot. The submarine is often able to track the surface ship during all this time. At least after clearing the area and returning at slow speed to actively search the area the surface ship has returned the game to an even state where both sides have a chance to detect the other.

 

 

Luck plays an important part in a surface ship detecting a submarine. About the only time the state of play is even is if a submarine is travelling quickly to reach or keep up with an active unit.

 

 

The Perry has a helicopter capable of searching for submarines which I chose not to use since I haven’t used helicopters and dropping sonar buoys yet. I can see the helicopter would search, find and track the submarine so the Perry could return knowing ranges etc to the submarine and fire if able.

 

 

 

Given this, submarines get to strike first against the surface target. After that, the initiative would shift to the Perry and helicopter team.

[CV32]

Interesting analysis. Thanks for sharing it. This will be the subject matter of the next Tactics 101 article, Part 4: ASW in HCE, which I am now starting to work on and which will hopefully be out in the Autumn.

 

Two important points arising, I think:

 

The importance of the surface ship towed array and the shipborne helicopter as equalizers (of sorts) in the battle of acoustics and tactical advantage with a submarine.

[kcdusk]

Interesting analysis. Thanks for sharing it. This will be the subject matter of the next Tactics 101 article, Part 4: ASW in HCE, which I am now starting to work on and which will hopefully be out in the Autumn.

 

Two important points arising, I think:

 

The importance of the surface ship towed array and the shipborne helicopter as equalizers (of sorts) in the battle of acoustics and tactical advantage with a submarine.

 

Thanks CV32.

Your right, an already deployed towed array would help! So would the hele, maybe thats what i need to try next.

 

Sorry for my ingnorance, where would the Tactics 101 article be published? Do your write for naval Reviews, your own website or something?

[CV32]

Sorry for my ingnorance, where would the Tactics 101 article be published? Do your write for naval Reviews, your own website or something?

 

Right here at HarpGamer.

[Silent Hunter UK]

The Victor III isn't the first Russian SSN - that honour goes to the Hotel - but it is the first one that is quiet enough to be a good attack platform.

[Warhorse64]

Erm ... Sorry, but Hotel class was an SSBN. The first Soviet SSN, IIRC, was the November class.

[Silent Hunter UK]

Erm ... Sorry, but Hotel class was an SSBN. The first Soviet SSN, IIRC, was the November class.

 

I stand corrected; it was the November, of course.