AIP vs nuclear submarines

[Indus Falcon]

Maybe the Americans already knew a Chinese sub would be tailing them, so instead of announcing it on CNN they kept quite. They let the Chinese sub get close, and had an American sub (or two) record the acoustic signatures of the Chinese sub? Just a theory!

 

[JSCh]

So all the acoustic signature of US carrier battle group are open secret?

Since sub from any countries can sneak into their inner perimeter and record whatever they want for any length of times, for any of the ship including the aircraft carrier?

And there is nothing that the US Navy can or would want to prevent that from happening?

 

[gambit]

So all the acoustic signature of US carrier battle group are open secret?

Since sub from any countries can sneak into their inner perimeter and record whatever they want for any length of times, for any of the ship including the aircraft carrier?

And there is nothing that the US Navy can or would want to prevent that from happening?

How can we keep those data secret in the first place ? By not sailing any ship at all, right?

 

[Penguin]

Maybe the Americans already knew a Chinese sub would be tailing them, so instead of announcing it on CNN they kept quite. They let the Chinese sub get close, and had an American sub (or two) record the acoustic signatures of the Chinese sub? Just a theory!

I think that is what T-AGOS ships are used for. SURTASS provides passive detection of quiet nuclear and diesel submarines and real-time reporting of surveillance information to theater commanders. Which explains China's actions against such ships. The SURTASS LFA (Low Frequency Active Sonar) on some (2-3) ships allows it to be used when a target is too quiet to be detected by the passive (SURTASS) system alone.
The US Navy -- Fact File: Ocean Surveillance Ships - T-AGOS
Surveillance Towed-Array Sensor System (SURTASS)
Ocean Surveillance Ships - AGOS
SURTASS LFA

 

[JSCh]

http://en.wikipedia.org/wiki/HMS_Swiftsure_(S126)

Swiftsure became famous for her mission to acquire the acoustic signature of the Soviet aircraft carrier Kiev.

Apparent the Brit is rather stupid to be famous and proud of something so easy to be accomplished.

 

[500]

COST

Cost of typical AIP sub is 100 million USD to 250 million USD, compared to 1,6 – 3 billion USD for typical nuclear submarine;

Best AIP sub (212) costs about 500-600 mln, best nuclear sub (Virgina) - about 1.8 bln .

Main advantage of modern submarine is stealth. While nuclear submarines have measures to reduce sound and magnetic signatures, nature of nuclear propulsion (steam turbine) makes them far more noisy than AIP submarine of same size. They also tend to be larger on a whole, making them even more detectable through either acoustic, infrared or magnetic sensors.

No. Modern nuclear submarines are virtually not detectable at slow speeds.

While Los Angeles class can dive to 450 meters regularly, German Type 214 (improved Type 212) can dive to 426 meters.

Actual depth are classified but I guess the difference is much bigger. And 214 is not improved 212, quite the opposite.

Nuclear submarines have cruise speeds of 20 – 25 knots, compared to 10 – 15 knots for AIP subs.

Thats silliest part of the article. Nuclear subs dont have a cruise speed, since their range is unlimited. They can travel at any speed up to 30+ knots they want as much as they want. Of course at high speeds they are noisy so maximum silent speed of modern submarine is about 20 knots.

AIP submarine has cruise speed of about 4 knots. In order to travel faster it needs to use either accumulators, which drain as fast as smartphones or shnorkel, which is noisy as hell and cant be used at depths or bad weather.

 

[IND151]

So long as it fits the tubes, and the sub is equipped with appropriate fire control, there is no reason why even a non-AIP conventional sub couldn't fire cruise missiles. Also there is no technical reason why such missiles would be limited to 250-300km.

Compare e.g. US Mk 48 torpedo and Tomahawk SLCM

Mk 48 torpedo
Length 19 feet (5.79 meters)
Weight 3,434 lbs (1545.3 kg) (MK-48);
3,695 lbs (1662.75 kg) (MK-48 ADCAP)
Diameter 21 inches (53.34 centimeters)
RangeOfficially "Greater than 5 miles (8 km)"

BGM-109 Tomahawk
Length: 18 feet 3 inches (5.56 meters); with booster: 20 feet 6 inches (6.25 meters)
Weight: 2,650 pounds (1192.5 kg); 3,200 pounds (1440 kg) with booster
Diameter: 20.4 inches (51.81 cm)
Wing Span: 8 feet 9 inches (2.67 meters)
Range:
Land attack, conventional warhead: 600 nautical miles (690 statute miles, 1104 km)


Or Russia's

533 mm (21") UGST wakehomer
Weight4,850 lbs. (2,200 kg)
Overall Length
283 in (7.200 m)

533 mm (21") USET-80 wakehomer
Weight4,410+ lbs. (2,000+ kg)
Overall Length311 in (7.900 m)


533 mm (21") VA-111 "Shkval" (Squall) supercavitating torp
Weight5,952 lbs. (2,700 kg)
Overall Length323 in (8.200 m)

S-10 Granat (SS-N-21 'Sampson';GRAU:3M10), SLCM

Weight 1,700 kg (3,750 lb)
Length 809 cm (26 ft 7 in)
Diameter 51 cm (20.1 in)
Operational range 3,000 km (1,600 nmi

That's nice explanation but, a diesel/ AIP sub can not carry missiles like R 39 with 10 MIRV warheads and 8,300 KM range, so SSBN will be unrivaled in that context.

 

[500]

That's nice explanation but, a diesel/ AIP sub can not carry missiles like R 39 with 10 MIRV warheads and 8,300 KM range, so SSBN will be unrivaled in that context.

there is no any connection between submarines weapons and propulsion system.

 

[Informant]

@gambit how does Ship radars work? And why stealth ships well so huge and a bit stealthy?

I cannot differentiate, please help out a layman.

 

[IND151]

there is no any connection between submarines weapons and propulsion system.

There is................

A diesel sub even with AIP will quickly run out of fuel if it carries 20 ICBMs like R 39.

Plus such sub will have to be very big as the diesel engine will have to be very powerful thus big and heavy.

Thus going for diesel you will get subs which is perhaps larger than even typhoon but very limited in range; this defeats the very idea of safe near continuous strategic deterrence.

 

[gambit]

@gambit how does Ship radars work? And why stealth ships well so huge and a bit stealthy?

I cannot differentiate, please help out a layman.

Radar detection is the same whether the target is a ship or an aircraft, or whether the seeking radar is on a ship or an aircraft. So if you want to make the ship 'stealthy' you just have to apply the same shaping tactics as you would for the aircraft.

On the one hand...The major difference here is that the ship is not as maneuverable as the aircraft and that the ship is limited to 2D space while the aircraft have 3D scope. That mean any for any radar contact with a ship, there will be more time to data process and detect the ship.

On the other hand...Precisely because the ship is limited to 2D maneuvers, any seeking radars on the ship will be limited by the horizon if it is a ship-to-ship engagement, or a shore-to-ship engagement.

Try this...

Horizon calculator - radar and visual

You can vary the altitude (H) as much as you like. But say we have two ships each with the same radar antenna elevation, say 10 meters for example, then each ship would have the maximum radar horizon of about 26 km distance out. So if you have one ship that is shaped for 'stealth', that ship would appear to be a very small target and perhaps small enough to be discarded as a non-threat.

That is why the Zumwalt is alleged to appear as small as a fishing boat -- black squares -- in a ship-to-ship or shore-to-ship engagement.

 

[Informant]

Radar detection is the same whether the target is a ship or an aircraft, or whether the seeking radar is on a ship or an aircraft. So if you want to make the ship 'stealthy' you just have to apply the same shaping tactics as you would for the aircraft.

On the one hand...The major difference here is that the ship is not as maneuverable as the aircraft and that the ship is limited to 2D space while the aircraft have 3D scope. That mean any for any radar contact with a ship, there will be more time to data process and detect the ship.

On the other hand...Precisely because the ship is limited to 2D maneuvers, any seeking radars on the ship will be limited by the horizon if it is a ship-to-ship engagement, or a shore-to-ship engagement.

Try this...

Horizon calculator - radar and visual

You can vary the altitude (H) as much as you like. But say we have two ships each with the same radar antenna elevation, say 10 meters for example, then each ship would have the maximum radar horizon of about 26 km distance out. So if you have one ship that is shaped for 'stealth', that ship would appear to be a very small target and perhaps small enough to be discarded as a non-threat.

That is why the Zumwalt is alleged to appear as small as a fishing boat -- black squares -- in a ship-to-ship or shore-to-ship engagement.

Wouldnt the upper portion, the building thing, have a bigger cross section? It is hardly different from the ship above?

 

[gambit]

Wouldnt the upper portion, the building thing, have a bigger cross section? It is hardly different from the ship above?

Look at it this way...

Upon radar bombardment, every structure, no matter how small, even surface scratches, to large structures like guns and ladders and hatches, are considered 'radiators', as in EM radiators. So the rules for 'stealth' shaping are:

Control of...
- Quantity of radiators
- Array of radiators
- Modes of radiation

Comparing the 'dirty' superstructures of the current ship designs to that of the much 'cleaner' Zumwalt, it is likely, and this is just my opinion, that the Z's superstructure is EM-wise no greater than the hull. The Z's superstructure is more 'solid' in appearance, but in 'stealth' shaping, appearances are often deceiving. The Z's superstructure have far less radiators (rule 1) than all current designs. A unitary superstructure is what the Z has while current designs have connected sections that varies in sizes and angles. A unitary superstructure is much easier and more efficient in obeying the three rules of 'stealth' shaping than current designs. There are no 'violations' of the rules, just more or less efficiency in obeying them.

 

[Informant]

Look at it this way...

Upon radar bombardment, every structure, no matter how small, even surface scratches, to large structures like guns and ladders and hatches, are considered 'radiators', as in EM radiators. So the rules for 'stealth' shaping are:

Control of...
- Quantity of radiators
- Array of radiators
- Modes of radiation

Comparing the 'dirty' superstructures of the current ship designs to that of the much 'cleaner' Zumwalt, it is likely, and this is just my opinion, that the Z's superstructure is EM-wise no greater than the hull. The Z's superstructure is more 'solid' in appearance, but in 'stealth' shaping, appearances are often deceiving. The Z's superstructure have far less radiators (rule 1) than all current designs. A unitary superstructure is what the Z has while current designs have connected sections that varies in sizes and angles. A unitary superstructure is much easier and more efficient in obeying the three rules of 'stealth' shaping than current designs. There are no 'violations' of the rules, just more or less efficiency in obeying them.

Aaah now i get an idea. But why Zumwalt the most advanced? Due to stealth or the technology in it?

 

[Indus Falcon]

Aaah now i get an idea. But why Zumwalt the most advanced? Due to stealth or the technology in it?

From what I understand, both.