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I have been taking a closer look at my ships in the space sport since there is no water to conceal whats underneath the hull. I noticed this weird round thing under Fushin. Interesting enough, Gnevny which is another variant of this ship does not have it. I also noticed that none of my other 70+ ships across all 4 classes also don't have this round thing.

 

 

Screenshot (501)_LI.jpg

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owo

 

 

Also, the jagged edge on the stabilizer is very strange.

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12 minutes ago, silverdahc said:

Might be sonar head

That is my thought too, active/passive sonar.

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This is supposed to have been an RN N-class destroyer, iirc.  They do have ASDIC built into the ships, as these were war-built DDs, so yeah, that's probably a sonar head.

Edited by mavfin87

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53 minutes ago, pikohan said:

owo

 

 

Also, the jagged edge on the stabilizer is very strange.

Not stabilizers, but bilge keels to control roll period of the ship. The dome is a sonar head, and most destroyers have them. They can be raised into the hull to limit drag as sonars of that era were useless above 18-20 knots. The jagged edge is bilge keel damage that happens in shallow depths, in docking in drydocks, or operating in sea ice.

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2 hours ago, GrandAdmiral_2016 said:

Not stabilizers, but bilge keels to control roll period of the ship. The dome is a sonar head, and most destroyers have them. They can be raised into the hull to limit drag as sonars of that era were has always been and will always be useless above 18-20 knots. The jagged edge is bilge keel damage that happens in shallow depths, in docking in drydocks, or operating in sea ice.

 

FTFY.

And it's a lot lower than 18-20 kts, too, where it gets useless. Flow noise and own-ship radiated noise drowns out everything else. Even a modern SQS-53C gets full of suck, and performance degrades quickly as soon as you start making more than just bare steerageway.

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54 minutes ago, LT_Rusty_SWO said:

 

FTFY.

And it's a lot lower than 18-20 kts, too, where it gets useless. Flow noise and own-ship radiated noise drowns out everything else. Even a modern SQS-53C gets full of suck, and performance degrades quickly as soon as you start making more than just bare steerageway.

True of ships with convention propulsion and shaft gearing setups, steam, diesel or gas turbine. Our current RCN frigates are like this. I am seeing many non-USN ships with insulated machinery platforms, turbo-electric drive, and 5-blade noiseless props that can run a ship up to the ship's natural hull wavelength speeds with only hull flow noise, plus they use towed arrays, active and passive, up to 21-24 knots, and this is very dependant on surface wave conditions above sea state 3, but they beat the hell out of conventional DD/frigate propulsion setups. Their achilles' heel is speed when chasing down SSN/SSBN that can go deep and run it up to 30+knots, as most of them are speed-limited due to the necessary low noise hull form to about 27 knots and are essentially useless without onboard ASW helicopters. AIP powered and conventional subs fear these ships. They are as expensive as hell to build as well.

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2 hours ago, GrandAdmiral_2016 said:

True of ships with convention propulsion and shaft gearing setups, steam, diesel or gas turbine. Our current RCN frigates are like this. I am seeing many non-USN ships with insulated machinery platforms, turbo-electric drive, and 5-blade noiseless props that can run a ship up to the ship's natural hull wavelength speeds with only hull flow noise, plus they use towed arrays, active and passive, up to 21-24 knots, and this is very dependant on surface wave conditions above sea state 3, but they beat the hell out of conventional DD/frigate propulsion setups. Their achilles' heel is speed when chasing down SSN/SSBN that can go deep and run it up to 30+knots, as most of them are speed-limited due to the necessary low noise hull form to about 27 knots and are essentially useless without onboard ASW helicopters. AIP powered and conventional subs fear these ships. They are as expensive as hell to build as well.

 

Isolation mounts for machinery are not new. That's been a thing for probably 50 years now, and we're pretty good at minimizing cavitation from the screws, too, and a lot of what we can't contain through good design practices gets handled by PRAIRIE/MASKER and similar stuff. 

Flow noise, though... you simply can't get rid of that. Not for a hull-mounted sonar, and there's no towed array in the world that can be pulled at 27 knots. That's why ASW ships tend to work in pairs when possible, and / or with air assets.

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Without air assets, ASW ships are just targets (so says the son of one of my friends and former co-workers, who is a Vice-Admiral and an ASW specialist). And they need a lot is air support, 24-7 in all weathers and sea conditions. Not the world's easiest job, especially in the North Atlantic and North Pacific, or close inshore anywhere.

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52 minutes ago, GrandAdmiral_2016 said:

Without air assets, ASW ships are just targets (so says the son of one of my friends and former co-workers, who is a Vice-Admiral and an ASW specialist). And they need a lot is air support, 24-7 in all weathers and sea conditions. Not the world's easiest job, especially in the North Atlantic and North Pacific, or close inshore anywhere.

 

Speaking as someone who's spent a fair amount of time doing ASW... he's not wrong.

 

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It's obviously a suction cup so you can mount it on the dashboard of a battleship.

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2 hours ago, Amenhir said:

It's obviously a suction cup so you can mount it on the dashboard of a battleship.

:Smile_veryhappy:

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5 hours ago, GrandAdmiral_2016 said:

Without air assets, ASW ships are just targets (so says the son of one of my friends and former co-workers, who is a Vice-Admiral and an ASW specialist). And they need a lot is air support, 24-7 in all weathers and sea conditions. Not the world's easiest job, especially in the North Atlantic and North Pacific, or close inshore anywhere.

Okay, now this always made me curious:

How do the vibrations from the rotors of an ASW Helicopter not travel into and disorient the Hydrophones? How does the force of the air moved by the ASW Helicopter's rotors on the water (which is nearly incompressible), not also create a disturbance?

That always seemed a little odd to me.

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2 hours ago, Carrier_Lexington said:

Okay, now this always made me curious:

How do the vibrations from the rotors of an ASW Helicopter not travel into and disorient the Hydrophones? How does the force of the air moved by the ASW Helicopter's rotors on the water (which is nearly incompressible), not also create a disturbance?

That always seemed a little odd to me.

Sonobuoys are dropped in patterns and left behind. The helo isn't always anywhere near them at any given time. Dipping sonar is variable depth, and generally deployed deep enough that there's no issues. That said, a submarine with good enough passive sonar, or one which is shallow enough, will be able to hear a helo overhead.

But... signal processing is the bigger factor.

The entire surface of the water is disturbed and confused, and has a lot of random sounds. Good sonar--or a good sonar operator--will filter out and reject wave noise, because it's looking for specific bands where a noise is repeated. Watch the linked video below. It's from a game, but it's legit the most accurate representation of sonar operation I've ever seen in a simulation, or of ASW in general. When you look at the time display (called a "waterfall," because everything falls from top to bottom of the screen, random noise just looks like static.... but you can see anything that repeats. Anything that shows up on a 50/60 hz line is going to be something worth giving a look at, because that's where power generator systems are running. (US/Canada: 60, most Euro-Rus-Chinese: 50)

Helo... you'd see a line, and it would probably be pretty bright, since it's loud at the surface. Helo rotors are going about 250 rpm or so, x4 (if it's a 4-bladed rotor) so about 1000 beats per minute. /60 equals about 16-17 hz. You'd see a distinctively different line for that.

 

 

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In ASW work you don't sonar dip often, you drop lines of dual mode active/passive sonobuoys that are data linked to the onboard systems on the chopper and directly to the ship (and other ships within the task group) as well, plus you use your MAD systems. The information they give out can be triangulated and plotted to determine the target sub's couse, speed, and depth by computer. With multiple platforms at varying locations treating the data, the sub knows that it has to shoot and scoot as silently as possible. Helicopter rotor noise is transmitted to the water when the chopper is within twice the rotor radius above the water, within what chopper pilots called the ground effect at hover. Dipping sonar can be either passive or active, but must be reeled down at about 20 meters or greater depth for best effect. Passive systems use prevails, because the minute you go active, even in a chopper, you become a target, as many modern subs have short range IR seeker AA missiles that allow them to neutralize attacking helicopters in an emergency. Subs sonars can identify and distinguish sound emissions sources even better than surface ships can, by noise signature recognition. This stuff has been around since the mid-1960s, and has been much improved upon. With sonars, magnetic anomaly detection (passive in nature), and now new submerged water displacement measurement (air and satellite) and infra-red/thermal imagery wake detection systems, all passive in nature, coming on line, frigates and DDs, working with rotary and fixed wing ASW aircraft, have stuff that make a submariner's life a little bit harder.

During WWII, IJN passive sonars were good enough to detected approaching US carrier aircraft attack groups, especially when they came in at low level, as far out as the first convergence zone, about 30-40 miles. They may have been late getting decent radar in service, but they had access to the excellent German sonar technologies as early as 1938, in additon to their own sonars, which were decent.

It is the old race between gun penetration and armor plate, taken to a new and modern level...and so far the subs still have the advantage....

Edited by GrandAdmiral_2016
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Dipping is used mostly for final attack stuff, or if you're out of sonobuoys... which happens a lot quicker than you'd like, usually. 

Also, MAD is not particularly useful unless you're dealing with a diesel boat that's snorting. And just OBTW, we're not putting MAD on things anymore. P8 doesn't have it, neither do the newest revs of the MH-60.

Edited by LT_Rusty_SWO

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They will regret the loss of MAD capability unless the new IR/thermal systems can get it done. We shall see....

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1 hour ago, GrandAdmiral_2016 said:

They will regret the loss of MAD capability unless the new IR/thermal systems can get it done. We shall see....

 

Yeah, no. MAD is not a great idea anymore. It's too short-range, and requires the target sub to be at PD.

You know what else can happen when you get close to a sub at PD?

 

 

 

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They shoot back...been around on Russian-built subs for almost 25 years now in earlier versions.. Going to be interesting following the development of ASW smart deep water influence mines as an area denial weapon against subs in littoral defence. Passive bottom huggers in deeper water are tough for minehunters to catch, and almost impossible for subs to detect. All kinds of stuff going on in ASW these days...

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7 minutes ago, GrandAdmiral_2016 said:

They shoot back...been around on Russian-built subs for almost 25 years now in earlier versions.. Going to be interesting following the development of ASW smart deep water influence mines as an area denial weapon against subs in littoral defence. Passive bottom huggers in deeper water are tough for minehunters to catch, and almost impossible for subs to detect. All kinds of stuff going on in ASW these days...

 

Captor mines will probably be a lot more interesting and useful. Use a Mk48 body the way that some do now, but have a hydrophone and a payload of a Mk46 / Mk50. Swim them up close to Vladivo... er, sorry, "some unnamed port," at low speed, then sit on the bottom in the channel and wait for the right blade count and a 50-hz line, then launch.

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19 hours ago, LT_Rusty_SWO said:

 

Captor mines will probably be a lot more interesting and useful. Use a Mk48 body the way that some do now, but have a hydrophone and a payload of a Mk46 / Mk50. Swim them up close to Vladivo... er, sorry, "some unnamed port," at low speed, then sit on the bottom in the channel and wait for the right blade count and a 50-hz line, then launch.

Preprogammed destruction. Do it off a PRC/PLAN port as well, they are starting to build respectable subs...but that would not be very friendly, would it...

 

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On ‎4‎/‎7‎/‎2018 at 1:38 PM, LT_Rusty_SWO said:

 

FTFY.

And it's a lot lower than 18-20 kts, too, where it gets useless. Flow noise and own-ship radiated noise drowns out everything else. Even a modern SQS-53C gets full of suck, and performance degrades quickly as soon as you start making more than just bare steerageway.

Back when Sonar was first used on ships, 10-15 knots depending on equipment, and what was done to the ship, to reduce self-noise-interference

Sonar today: 20+ knots, depending on equipment and what was done to the ship to reduce self-noise-interference.

Virginia Class nuclear submarine, is capable of utilizing sonar without fail, while traveling 25 knots, submerged. 25 knots or lower is what is called "silent" because of the lack of interference to its own sonar equipment.

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57 minutes ago, Counter_Gambit said:

Virginia Class nuclear submarine, is capable of utilizing sonar without fail, while traveling 25 knots, submerged. 25 knots or lower is what is called "silent" because of the lack of interference to its own sonar equipment.

 

Lot of variables go into that, man. LOT of variables. Depth being a big one.

Also, remember that the faster you go the more error you're going to have, too, just based on the speed of sound, the range to the target, and how long it takes a sound to get to you.

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On 4/7/2018 at 7:47 AM, pikohan said:

owo

 

 

Also, the jagged edge on the stabilizer is very strange.

I have worked on some boats that have bilge keels that look like that. But that's after hard use not what you'd expect from a pixel ship. I work on the largest drydock on the west coast IRL.

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