The Macabees
23-05-2005, 03:10
[Images]
http://www.fas.org/man/dod-101/sys/ship/ssn-virginia-56.jpg
http://www.naval-technology.com/projects/nssn/images/nssn5.jpg
[Abstract]
After many years of success regarding the use of the Toledo class SSN it was decided that a newer, more advance, and much more effective nuclear attack submarine was needed if the Empire's submarine naval force was to stay on par with other naval powers around the world. Consequently, by the accension of Jonach to the government in 2005 the administration had put money into a new project, labeled S116, destined to craft the new Cartagena class SSN [501].
The Cartagena class SSN is a top of the line submarine, developed with amongst the best technologies currently available around the world, and some only available to allied states. The Cartagena is destined to make its name known around the world, and in accordance has been opened for export.
The Golden Throne has ordered a total of four hundred of the new SSNs, replacing all four hundred of the Toledo class SSNs which are to be mothballed, and consequently scrapped for construction of other submersibles. The Cartagena is to be one of the most widely used submarines around the world, especially in the Golden Throne's and allied navies.
The ship is designed using a state-of-the-art digital database, which allows members of the IPPD teams to work from a single design database and provides three-dimensional electronic mockups throughout the design process.
[Hull Design and Construction]
The Cartagena class SSN takes on a teardrop shape, as seen in the Virginia class SSN, and showing resemblence to technology first released with the Soviet/Russian Kilo class SSK [diesel attack submarine]. The teardrop shape was designed to further disperse the pressure mounted by water, especially at lower depths. Meaning, the rounder shape of the aft of the submarine allows the water to disperse around the hull, avoiding mounting pressure on a single point, as the water "flows" around the hull. Therefore, the teardrop shaped hull gives the Cartagena a much larger crush depth.
The frame of the Cartagena class SSN is fully made of titanium, amongst the strongest conventional metals known to man. Although rather expensive, it does allow to extend the much important crush depth needed for modern submarines. Furthermore, it gives the hull a greater tensile strength, and should be able to survive up to, and perhaps more than, two standard ADCAP [MK 48] torpedoes.
The hull is constructed of a composite material, designed by Imperial engineers. Namely, a polymer material [or plastic material] is weaved around a matrix, giving it additional strength for resistance. The polymer is also reinforced with titanium and steel strands, as well as the ceramics found in chobham and cermat. Furthermore, there are also strands of depleted uranium and vanadium, giving the hull a strength proportional to that of a surface ship. There are also several bulkheads and a host of NBC protection agents, in order to defend from chemical to nuclear attacks in the submarine layer.
The hull and frame gives the Cartagena class SSN an outstanding crush depth of 2.5 kilometers under perfect circumstances. The hull also incorporates ROR-CHO composite technology developed by BFGoodrich which give the submarine and its sonar windows awesome acoustical performance, while keeping structural integrity.
Moreover, the hull and screws are pocketed by Super Flow cavitation absorbers. SuperFlow power absorbers use forged stainless steel shafts, which have internal hubs for attachment of the impeller. The attachment point to the hub is part of the forging, not a keyway or serration. The stainless steel forged shafts, used in the dynamometers currently available on SF-901s, have not experienced a single failure in their current configurations, going back a number of years. The SuperFlow absorber design uses a rounded pocket which is considerably more efficient at transferring torque, while reducing the shock effect of the water moving from the rotor to the stator. As a consequence, the rotor is smaller in diameter and contains much less volume for rapid response. The area exposed to the water is less, and many of these units have been in operation more than 15 years at this time. The SuperFlow dynamometers are used extensively for endurance testing, and customers report accumulating more than 10,000 hours on the absorbers. SuperFlow’s durability is proven by many years of in-field use.
Finally, the hull is layered with a thin strip of gaucho, a black rubbery substance designed to absorb active sound waves, as well as anechoic tiling.
[Propulsion]
The Cartagena class SSN is driven by a single Baldur pebble bed nuclear reactor. The Pebble Bed Modular Reactor (PBMR) is a new type of high temperature helium gas-cooled nuclear reactor, which builds and advances on world-wide nuclear operators' experience of older reactor designs. The most remarkable feature of these reactors is that they use attributes inherent in and natural to the processes of nuclear energy generation to enhance safety features. More importantly, it is also a practical and cost-effective solution to most of the logistics of generating electricity.
http://www.eskom.co.za/nuclear_energy/pebble_bed/image1_2.gif
To protect the reactor there are several infra-red detection devices around the uranium core, and at a note from a pressure sensor, either made by water or a man made collision, the Baldur nuclear reactor is automatically shut off, save for the coolant flow.
http://www.eskom.co.za/nuclear_energy/pebble_bed/coated_part.gif
The nature of the chain reaction that takes place in the PBMR is exactly the same as the one that takes place at Koeberg. (Refer to Koeberg experience - Fuel )
The fuel used in a PBMR consists of "spheres" which are designed in such a way that they contain their radioactivity. The PBMR fuel is based on proven high quality fuel used in Germany.
Each sphere is about the size of a tennis ball and consists of an outer graphite matrix (covering) and an inner fuel zone The fuel zone of a single sphere can contain up to 15 000 "particles". Each particle is coated with a special barrier coating, which ensures that radioactivity is kept locked inside the particle. One of the barriers,the silicon carbide barrier, is so dense that no gaseous or metallic radioactive products can escape. (it retains its density up to temperatures of over 1 700 degrees Celsius). The reactor is loaded with over 440 000 spheres - three quarters of which are fuel spheres and one quarter graphite spheres - at any one time. Fuel spheres are continually being added to the core from the top and removed from the bottom. The removed spheres are measured to see if all the uranium has been used. If it has, the sphere is sent to the spent fuel storage system, and if not, it is reloaded in the core. An average fuel sphere will pass through the core about 10 times before being discharged. the graphite spheres are always re-used. The graphite spheres are used as a moderator. They absorb and reduce the energy of the neutrons so that these can reach the right energy level needed to sustain the chain reaction.
[Electronic Detection Devices]
AN/BQQ-5 Sonar
AN/BQQ-5 bow-mounted spherical array sonar acoustic system is deployed on SSN 637 and SSN 501 attack submarine classes. This low frequency passive and active search and attack sonar is supplied by IBM. The AN/BQQ-5E sonar with the TB-29 towed array and Combat Control System (CCS) Mk 2, known collectively as the QE-2 System, provides a functionally equivalent system for the Cartagena class submarines. Enhancements include increases in acoustic performance, improved combat control capabilities and replacement of obsolete equipment.
OPEVAL for AN/BQQ-5E system with the TB-29 Array completed in FY 1998; this system will provide quantum improvements in long-range detection and localization for SSN 501 Class Submarines. Engineering Change Proposal (ECP) 7001 to AN/BQQ-5E will provide Low Frequency Active Interference Rejection, Dual Towed Array Processing, and Full Spectrum Processing to SSN 501 Class Submarines.
The AN/BSY-1 ECP 1000, the AN/BQQ-5 Medium Frequency Active Improvement program and Improved Control Display Console Obsolete Equipment Replacement have been modified to become the basis of the Acoustics Rapid Commercial Off The Shelf Insertion (A-RCI) program. A-RCI is a multi-phased, evolutionary development effort geared toward addressing Acoustic Superiority issues through the rapid introduction of interim development products applicable to SSN 501,Class Submarines. A-RCI Phases I and II introduce towed array processing improvements; A-RCI Phase III introduces spherical array processing improvements.
The Cartagena Submarine System Improvement Program develops and integrates command and control improvements needed to maintain Cartagena submarine operational capability through the life cycle of this vital strategic asset. The program conducts efforts needed to ensure platform invulnerability, and reduce life cycle costs. Recent efforts have included the development of AN/BQQ-6 Sonar to AN/BQQ-5E Sonar Translator.
TB-113, TB-23 Towed Array and TACTAS
The TB-113 towed array is the newest towed array currently in service with the Imperial Navy. Being about three times as long as the current Elusive class Battleship it also has a grand host of hundreds of sensitive hydrophones running down the final seventy-five meters length of steel wire.
It was designed to supplement the AN/BQQ-5 spherical array, and to exceed existent towed arrays. However, the older TB-23 towed array is still in use, being the only short towed array in service with the Imperial Navy.
The AN/SQR-19 Tactical Towed Array SONAR (TACTAS) provides very long-range passive detection of enemy submarines. TACTAS is a long cable full of microphones that is towed about a mile behind the ship. It is towed so far behind the ship so as to not let noise radiating from the shipitself interfere with the noise picked up from targets. Using that noise can determine exactly what ship or submarine is being tracked. The AN/SQR-19B Tactical Array SONAR (TACTAS) is a passive towed array system which provides the ability to detect, classify, and track a large number of submarine contacts at increased ranges. TACTAS is a component sensor of the AN/SQQ-89(V)6 ASW Combat System, and provides significant improvements in passive detection and localization, searching throughout 360 degrees at tactical ship speeds. Processing of complex TACTAS data is performed by the largest computer program assembly ever developed for surface ship anti-submarine warfare.
Meteorology and Oceanography Center Detachment TACTAS support products describe oceanographic and acoustic conditions (using range dependent models) in the prosecution area for towed array ships tasked by CTF-69 for ASW operations. This message is provided when own ship Sonar In-situ Mode Assessment System (SIMAS) or the Mobile Environmental Team’s Mobile Oceanographic Support System MOSS) are not available. It is tailored to the specific towed array carried onboard. The message is transmitted prior to the start of a prosecution and daily thereafter or as requested.
General SONAR Use
Anti-submarine warfare (ASW) usually, but not always, involves the use of sonar. Although the vagaries of the environment make it difficult to predict and use, there is no other type of energy propagation that travels so far in the ocean without significant losses as acoustics waves. In this section, we describe the principles of operation of the major types of sonar systems and one non-acoustic system (MAD). We begin with the system that most closely resembles the operation of basic radar, namely active sonar.
Transmitter. The transmitter generates the outgoing pulse. It determines pulse width, PRF, modulation (optional), and carrier frequency. The output power can be controlled by the operator. The source level may be limited for several reasons. If the transducers are driven with too much power, they can cavitate (drop the pressure so low that the water boils). This is called quenching, and it can destroy the transducer since the normal backpressure is removed when bubbles form on its surface. Since the normal restoring force is gone, the surface of the transducer can travel too far (over-range) and damage itself. The quenching power limit increases with depth due to the increased ambient pressure.
Another common phenomenon that limits the maximum source level is reverberation, which is an echo from the immediate surrounding volume of water. The reverberation level (RL) increases with the source level (SL). At some point the reverberation exceeds the noise level (NL) and will dominate the return signal. Since reverberation always comes back from the same direction you are projecting, the reduction in background noise, quantified by the directivity index (DI) does not apply. When
RL > NL - DI,
the system is said to be reverberation-limited. The figure of merit equation must be modified to reflect this:
FOMactive (reverberation-limited) = SL + TS - RL - DT
When the system becomes reverberation-limited, the display will begin to be dominated by noise near own ship in the direction the active sonar is projecting. The solution is to reduce power to just below the level at which reverberation-limiting occurred.
Transducer array. The individual transducers are simple elements with little or no directionality. They are arranged in an array to improve the directivity index, which improves the figure-of-merit by noise reduction. The array of transducers reduces the beamwidth in the horizontal (or azimuthal) direction, and is usually circular in order to give more or less complete coverage, with the exception of the region directly behind the array (where the ship is). The array is protected from noise by own ship by discontinuing the array in the after regions, and also by putting in sound attenuating material. This region aft of a hull-mounted array, from which the sonar system cannot detect is called the baffles.
The array is also configured to reduce the beamwidth in the vertical direction. Normally a hull-mounted array should only receive sound from the downward direction, not directly ahead, since the noise from the ocean's surface would destroy the sonar's performance.
Beamforming processor. The input/output of each transducer is put through a beamforming processor, which applies time delays or phase shifts to each of the signals in such a way as to create a narrow beam in a particular direction.
The width of the beam formed by the beamforming processor will determine the bearing accuracy of the system when searching. In an identical manner to dual-beam tracking systems, sonar tracking systems can improve on this accuracy tremendously, at the expense of the signal-to-noise ratio.
4.) Duplexer. The duplexer performs the same function in an active sonar as in a radar system, namely to protect the receiver from the full transmitter power while the pulse is going out. It can be thought of a switch that toggles between the transmitter and receiver.
5.) Synchronizer. Performs same role as the synchronizer in radar. Provides overall coordination and timing for the system. Reset the display for each new pulse in order to make range measurements.
6.) Receiver. Collects the received energy. The receiver compares the power level to noise with a threshold SNR (DT) in order to determine if the signal will be displayed in a particular beam. If the DT is set too low, there will many false alarms. If it is too high, some detection capability will be lost.
The receiver may also demodulate the return if frequency modulation is used on transmission. Sonar systems often use pulse compression techniques to improve range resolution.
7.) Display. Puts all of the detection information into a visual format. There are several types:
A-scan: the signal along a single beam for a portion of the listening cycle. A target appears as a raised section if it is in the beam.
Passive SONAR:
Hydrophone array. These are the sensitive elements which detect the acoustic energy emitted from the target. Again, they are arranged into an array to improve the beamwidth. Common configurations are cylindrical or spherical. The cylindrical array operates at a fixed vertical angle, usually downward. The spherical array, which is common on submarines, has a much wider vertical field-of-view. Since the submarine may be below what it is tracking, the array must be able to look upwards to some extent. The large downward angles are only used for bottom bounce detection. Using a beamforming processor (described below) the field-of-view is broken down into individual beams in the vertical and azimuthal directions.
Beamforming processor. Unlike active systems which transmit and receive in a set direction, the passive system must listen to all angles at all times. This requires a very wide beamwidth. At the same time, a narrow beamwidth is required for locating the source and rejecting ambient noise. These two objectives are achieved simultaneously by the passive beamforming processor. The idea is very similar to the active system.
The beams should not be thought of as coming from the individual hydrophones. In fact, each of the beams so created has a narrow beamwidth that comes from the full aperture of the array, not the individual hydrophones.
Broadband display. The output of the beamforming processor is displayed as a bearing time history (BTH):
The newest information is at the top of the display. The beamwidth of the system determines how accurately the bearing can be measured by such a display. A common beamwidth is about 5o. The total amount of time displayed from top to bottom can be controlled (to some extent). A quickly updating display that only kept information for a few minutes would be useful for close contacts whose bearings are changing rapidly. On the other hand, a long tie history is more useful for detecting long range contacts, whose bearings are only changing slowly.
4.) Frequency Analyzer. The frequency analyzer breaks the signal into separate frequencies. This is the spectrum of the signal. For processing purposes, the frequencies are divided into small bands known as frequency bins. The width of each bin is called the analysis bandwidth. Sonar systems can gain considerable signal-to-noise improvements by matching the analysis bandwidth to the bandwidth of narrowband sources. The way to illustrate this is by two counter examples. If the signal processing bandwidth is too wide, then noise from the part of the spectrum beyond the signal is let in and the SNR is degraded. If the bandwidth is too narrow, then part of the signal is excluded, also reducing the SNR. It should be obvious now that the best situation occurs when the bandwidth exactly matches the signal. This is possible when the characteristics of the signal are well known, which they are for most targets.
The frequency analyzer separates (filters) the signal into discrete bins, inside of which the SNR is maximized. The frequency content of the signals from a target information provides vital information about its identity and operation. These frequencies are also subject to the Doppler shift, just like radar, are therefore can provide information about the range rate. This requires that the original frequency be known exactly, which is generally not the case. However, many important facts can be inferred by the changes in the received frequency over time.
Narrowband Display. For a particular beam, the time history of the frequency is called a waterfall display.
This can be used to gain additional information from a contact which is already being tracked by another system. In order to search for contacts on the basis of narrowband information alone requires a different type of display. One possibility is to simultaneously display several different beams, each showing a mini-waterfall display, which are called grams.
These are quite useful, but require great concentration on the part of the operator because there is more information displayed at any one time. Many systems require the operator to systematically search the entire field-of-view, looking at only a few beams at a time.
Variable Depth Sonar (VDS)
Variable depth sonars use large transducers that are towed from the ship on a cable with an adjustable scope. The combination of the buoyancy, ship speed and cable scope determine at the depth that the transducer will be at. VDS is used for two main reasons. At increased depth, the source level (SL) can be increased greatly, since the quenching limit is higher. This is due to increased backpressure on the surface of the transducer. Secondly, the VDS can be operated below the layer.
Recall that the combination of positive over negative sound velocity profiles created a layer at the interface. The layer makes it difficult to propagate sound across it. Therefore, ships using hull-mounted sonar systems will be unable to detect submarines operating below the layer, except possibly at short range. However, if the VDS can be place below layer, the ship can take advantage of the deep sound channel while being in the shadow zone of the submarine's sonar.
ZW-07 Surface Search RADAR
The radar has a peak power of 50 or 60 kW (pulse width 1 microsecond, PRF 1200 pps). There are also a short-pulse mode (0.1 microsecond, 100 kW, can be 2500 pps). Gain is 28 dB; dimensions of the half-cheese antenna are 1.0 x 0.25 m. The beam is 2.4 x 16 deg.
Performance: The range remains at around 200 nautical miles. In the single-pulse mode a ship can be detected at two hundred and ten nautical miles. The ZW-07 radar is installed on the Cartagena SSN.
http://www.dutchsubmarines.com/rd/images/equipm_zw-07.jpg
Inertial Guidance
An inertial navigation system measures the position and attitude of a vehicle by measuring the accelerations and rotations applied to the system's inertial frame. It is widely used because it refers to no real-world item beyond itself. It is therefore immune to jamming and deception. (See relativity and Mach's principle for some background in the physics involved).
An inertial guidance system consists of an inertial navigation system combined with control mechanisms, allowing the path of a vehicle to be controlled according to the position determined by the inertial navigation system. These systems are also referred to as an inertial platform.
INSs have angular and linear accelerometers (for changes in position); some include a gyroscopic element (for maintaining an absolute positional reference).
Angular accelerometers measure how the vehicle is twisting in space. Generally, there's at least one sensor for each of the three axes: pitch (nose up and down), yaw (nose left and right) and roll (clockwise or counterclockwise from the cockpit).
Linear accelerometers measure how the vehicle moves. Since it can move in three axes (up & down, left & right, forward & back), it has a linear accelerometer for each axis.
A computer continually calculates the vehicle's current position. First, for each of six axes, it adds the amount of acceleration over the time to figure the current velocity of each of the six axes. Then it adds the distance moved in each of the six axes to figure the current position.
Inertial guidance is impossible without computers. The desire to use inertial guidance in the minuteman missile and Apollo program drove early attempts to miniaturize computers.
Inertial guidance systems are now usually combined with satellite navigation systems through a digital filtering system. The inertial system provides short term data, while the satellite system corrects accumulated errors of the inertial system.
Schemes
Gyrostabilized platforms
Some systems place the linear accelerometers on a gimballed gyrostabilized platform. The gimbals are a set of three rings, each with a pair of bearings at right angles. They let the platform twist in any rotational axis. There are two gyroscopes (usually) on the platform.
Why do the gyros hold the platform still? Gyroscopes try to twist at right angles to the angle at which they are twisted (an effect called precession). When gyroscopes are mounted at right angles and spin at the same speed, their precessions cancel, and the platform they're on will resist twisting.
This system allowed a vehicle's roll, pitch and yaw angles to be measured directly at the bearings of the gimbals. Relatively simple electronic circuits could add up the linear accelerations, because the directions of the linear accelerometers do not change.
The big disadvantage of this scheme is that it has a lot of precision mechanical parts that are expensive. It also has moving parts that can wear out or jam, and is vulnerable to gimbal lock.
The gudiance system of the Apollo command modules used gyrostabilized platforms, feeding data to the Apollo Guidance Computer
Rate Gyro Systems
Lightweight digital computers permit the system to eliminate the gimbals. This reduces the cost and increases the reliability by eliminating some of the moving parts. Angular accelerometers called "rate gyros" measure how the angular velocity of the vehicle changes. The trigonometry involved is too complex to be accurately performed except by digital electronics.
Laser Gyros
Laser gyros were supposed to eliminate the bearings in the gyroscopes, and thus the last bastion of precision machining and moving parts.
A laser gyro moves laser light in two directions around a circular path. As the vehicle twists, the light has a doppler effect. The different frequencies of light are mixed, and the difference frequency (the beat frequency) is a radio wave whose frequency is supposed to be proportional to the speed of rotation.
In practice, the electromagnetic peaks and valleys of the light lock together. The result is that there's no difference of frequencies, and therefore no measurement.
To unlock the counter-rotating light beams, laser gyros either have independent light paths for the two direction (usually in fiber optic gyros), or the laser gyro is mounted on a sort of audio speaker that rapidly shakes the gyro back and forth to decouple the light waves.
Alas, the shaker is the most accurate, because both light beams use exactly the same path. Thus laser gyros retain moving parts, but they don't move as much.
Brandy Snifter Gyros
If a standing wave is induced in a globular brandy snifter, and then the snifter is tilted, the waves continue in the same plane of movement. They don't tilt with the snifter. This trick is used to measure angles. Instead of brandy snifters, the system uses hollow globes machined from piezoelectric matierals such as quartz. The electrodes to start and sense the waves are evaporated directly onto the quartz.
This system almost has no moving parts, and it's very accurate. It's still expensive, though, because precision ground and polished hollow quartz spheres just aren't cheap.
Quartz Rate Sensors
This system is usually integrated on a silicon chip. It has two mass-balanced quartz tuning forks, arranged "handle-to-handle" so forces cancel. Electrodes of aluminum evaporated on the forks and the underying chip both drive and sense the motion. The system is both manufacturable and inexpensive. Since quartz is dimensionally stable, the system has a good possibility of accuracy.
As the forks are twisted about the axis of the handle, the vibration of the tines tends to continue in the same plane of motion. This motion has to be resisted by electrostatic forces from the electrodes under the tines. By measuring the difference in capacitance between the two tines of a fork, the system can determine the rate of angular motion.
Pendular Accelerometers
The basic accelerometer is just a mass with a ruler attached. The ruler may be an exotic electromagnetic sensor, but it still senses distance. When the vehicle accelerates, the mass moves, and ruler measures the movement. The bad thing about this scheme is that it needs calibrated springs, and springs are nearly impossible to make consistent.
A trickier system is to measure the force needed to keep the mass from moving. In this scheme, there's still a ruler, but whenever the mass moves, an electric coil pulls on the mass, cancelling the motion. The stronger the pull, the more acceleration there is. The bad thing about this is that very high accelerations, say from explosions, impacts or gunfire, can exceed the capacity of the electronics to cancel. The sensor then loses track of where the vehicle is.
Both sorts of accelerometers have been manufactured as integrated micromachinery on silicon chips.
Accelerometer-only Systems
Some systems use four pendular accelerometers to measure all the possible movements and rotations. Usually, these are mounted with the weights in the corners of a tetrahedron. Thus, these are called "tetrahedral inertial platforms", or TIPs.
When the vehicle rolls, the masses on opposite sides will be accelerated in opposite directions. When the vehicle has linear acceleration, the masses are accelerated in the same direction. The computer keeps track.
TIPs are cheap, lightweight and small, especially when they use imicromachined integrated accelerometers. However currently (2002) they are not very accurate. When they're used, they're used in small missiles.
[Photonic Mast]
http://static.howstuffworks.com/gif/photonic-mast-a.jpg
Despite its valued service for more than ten years, the Imperial Navy will soon say "so long" to the conventional periscope. In 2005, construction began on a new breed of attack submarines that won't have a periscope. Instead, these new Cartagena-class submarines will use non-penetrating imaging devices called photonics masts to perform surveillance tasks. Each new submarine will be equipped with two photonics masts, which are basically arrays of high-resolution cameras that capture and send visual images to flat-panel displays in the control room.
[Weapons]
The Cartagena will have eight forward tubes, designed at 500mm width. The tubes will be able to fire virtually any Imperial torpedo design, including the MT-1, MT-2, MT-3 and MT-4. The tubes will also be used to release SSIXS transmission canisters.
Furthermore, the Cartagena is designed with four quadruple cell VLS tubes for a launch sequence of twelve missiles within eight seconds. VLS tubes employed by the Cartagena will be of the same make as those employed on other submersible and surface ships. Meaning, after one missile is launched the entire VLS apparatus uses heavy hydraulics to spin, and in that way while one missile launches another cell restocks, ergo, the VLS tubes never have to stop firing, and instead reload on the move.
The VLS cells are designed to fire Principe III, Shockhound Avenger I and Praetorian V missiles.
The Cartagena can also carry up to two hundred mines and a single Bilbao class UUV.
Finally, the Cartagena wields five retractable ASHUM guns for anti-torpedo defenses.
[Statistics]
Beam: 34 ft.
Length: 377 ft.
Submerged Displacement: 8,100 tons
Submerged Velocity: 28 knots
Crew: 121 Men and Officers
[Cost]
Each Cartagena class SSN will be exported for 1.1 billion USD. Production rights can only be sold to allies for a limited time for 250 billion, on the requirement that at least ten Cartagenas are purchases for full price alongside the order of production rights.
http://www.fas.org/man/dod-101/sys/ship/ssn-virginia-56.jpg
http://www.naval-technology.com/projects/nssn/images/nssn5.jpg
[Abstract]
After many years of success regarding the use of the Toledo class SSN it was decided that a newer, more advance, and much more effective nuclear attack submarine was needed if the Empire's submarine naval force was to stay on par with other naval powers around the world. Consequently, by the accension of Jonach to the government in 2005 the administration had put money into a new project, labeled S116, destined to craft the new Cartagena class SSN [501].
The Cartagena class SSN is a top of the line submarine, developed with amongst the best technologies currently available around the world, and some only available to allied states. The Cartagena is destined to make its name known around the world, and in accordance has been opened for export.
The Golden Throne has ordered a total of four hundred of the new SSNs, replacing all four hundred of the Toledo class SSNs which are to be mothballed, and consequently scrapped for construction of other submersibles. The Cartagena is to be one of the most widely used submarines around the world, especially in the Golden Throne's and allied navies.
The ship is designed using a state-of-the-art digital database, which allows members of the IPPD teams to work from a single design database and provides three-dimensional electronic mockups throughout the design process.
[Hull Design and Construction]
The Cartagena class SSN takes on a teardrop shape, as seen in the Virginia class SSN, and showing resemblence to technology first released with the Soviet/Russian Kilo class SSK [diesel attack submarine]. The teardrop shape was designed to further disperse the pressure mounted by water, especially at lower depths. Meaning, the rounder shape of the aft of the submarine allows the water to disperse around the hull, avoiding mounting pressure on a single point, as the water "flows" around the hull. Therefore, the teardrop shaped hull gives the Cartagena a much larger crush depth.
The frame of the Cartagena class SSN is fully made of titanium, amongst the strongest conventional metals known to man. Although rather expensive, it does allow to extend the much important crush depth needed for modern submarines. Furthermore, it gives the hull a greater tensile strength, and should be able to survive up to, and perhaps more than, two standard ADCAP [MK 48] torpedoes.
The hull is constructed of a composite material, designed by Imperial engineers. Namely, a polymer material [or plastic material] is weaved around a matrix, giving it additional strength for resistance. The polymer is also reinforced with titanium and steel strands, as well as the ceramics found in chobham and cermat. Furthermore, there are also strands of depleted uranium and vanadium, giving the hull a strength proportional to that of a surface ship. There are also several bulkheads and a host of NBC protection agents, in order to defend from chemical to nuclear attacks in the submarine layer.
The hull and frame gives the Cartagena class SSN an outstanding crush depth of 2.5 kilometers under perfect circumstances. The hull also incorporates ROR-CHO composite technology developed by BFGoodrich which give the submarine and its sonar windows awesome acoustical performance, while keeping structural integrity.
Moreover, the hull and screws are pocketed by Super Flow cavitation absorbers. SuperFlow power absorbers use forged stainless steel shafts, which have internal hubs for attachment of the impeller. The attachment point to the hub is part of the forging, not a keyway or serration. The stainless steel forged shafts, used in the dynamometers currently available on SF-901s, have not experienced a single failure in their current configurations, going back a number of years. The SuperFlow absorber design uses a rounded pocket which is considerably more efficient at transferring torque, while reducing the shock effect of the water moving from the rotor to the stator. As a consequence, the rotor is smaller in diameter and contains much less volume for rapid response. The area exposed to the water is less, and many of these units have been in operation more than 15 years at this time. The SuperFlow dynamometers are used extensively for endurance testing, and customers report accumulating more than 10,000 hours on the absorbers. SuperFlow’s durability is proven by many years of in-field use.
Finally, the hull is layered with a thin strip of gaucho, a black rubbery substance designed to absorb active sound waves, as well as anechoic tiling.
[Propulsion]
The Cartagena class SSN is driven by a single Baldur pebble bed nuclear reactor. The Pebble Bed Modular Reactor (PBMR) is a new type of high temperature helium gas-cooled nuclear reactor, which builds and advances on world-wide nuclear operators' experience of older reactor designs. The most remarkable feature of these reactors is that they use attributes inherent in and natural to the processes of nuclear energy generation to enhance safety features. More importantly, it is also a practical and cost-effective solution to most of the logistics of generating electricity.
http://www.eskom.co.za/nuclear_energy/pebble_bed/image1_2.gif
To protect the reactor there are several infra-red detection devices around the uranium core, and at a note from a pressure sensor, either made by water or a man made collision, the Baldur nuclear reactor is automatically shut off, save for the coolant flow.
http://www.eskom.co.za/nuclear_energy/pebble_bed/coated_part.gif
The nature of the chain reaction that takes place in the PBMR is exactly the same as the one that takes place at Koeberg. (Refer to Koeberg experience - Fuel )
The fuel used in a PBMR consists of "spheres" which are designed in such a way that they contain their radioactivity. The PBMR fuel is based on proven high quality fuel used in Germany.
Each sphere is about the size of a tennis ball and consists of an outer graphite matrix (covering) and an inner fuel zone The fuel zone of a single sphere can contain up to 15 000 "particles". Each particle is coated with a special barrier coating, which ensures that radioactivity is kept locked inside the particle. One of the barriers,the silicon carbide barrier, is so dense that no gaseous or metallic radioactive products can escape. (it retains its density up to temperatures of over 1 700 degrees Celsius). The reactor is loaded with over 440 000 spheres - three quarters of which are fuel spheres and one quarter graphite spheres - at any one time. Fuel spheres are continually being added to the core from the top and removed from the bottom. The removed spheres are measured to see if all the uranium has been used. If it has, the sphere is sent to the spent fuel storage system, and if not, it is reloaded in the core. An average fuel sphere will pass through the core about 10 times before being discharged. the graphite spheres are always re-used. The graphite spheres are used as a moderator. They absorb and reduce the energy of the neutrons so that these can reach the right energy level needed to sustain the chain reaction.
[Electronic Detection Devices]
AN/BQQ-5 Sonar
AN/BQQ-5 bow-mounted spherical array sonar acoustic system is deployed on SSN 637 and SSN 501 attack submarine classes. This low frequency passive and active search and attack sonar is supplied by IBM. The AN/BQQ-5E sonar with the TB-29 towed array and Combat Control System (CCS) Mk 2, known collectively as the QE-2 System, provides a functionally equivalent system for the Cartagena class submarines. Enhancements include increases in acoustic performance, improved combat control capabilities and replacement of obsolete equipment.
OPEVAL for AN/BQQ-5E system with the TB-29 Array completed in FY 1998; this system will provide quantum improvements in long-range detection and localization for SSN 501 Class Submarines. Engineering Change Proposal (ECP) 7001 to AN/BQQ-5E will provide Low Frequency Active Interference Rejection, Dual Towed Array Processing, and Full Spectrum Processing to SSN 501 Class Submarines.
The AN/BSY-1 ECP 1000, the AN/BQQ-5 Medium Frequency Active Improvement program and Improved Control Display Console Obsolete Equipment Replacement have been modified to become the basis of the Acoustics Rapid Commercial Off The Shelf Insertion (A-RCI) program. A-RCI is a multi-phased, evolutionary development effort geared toward addressing Acoustic Superiority issues through the rapid introduction of interim development products applicable to SSN 501,Class Submarines. A-RCI Phases I and II introduce towed array processing improvements; A-RCI Phase III introduces spherical array processing improvements.
The Cartagena Submarine System Improvement Program develops and integrates command and control improvements needed to maintain Cartagena submarine operational capability through the life cycle of this vital strategic asset. The program conducts efforts needed to ensure platform invulnerability, and reduce life cycle costs. Recent efforts have included the development of AN/BQQ-6 Sonar to AN/BQQ-5E Sonar Translator.
TB-113, TB-23 Towed Array and TACTAS
The TB-113 towed array is the newest towed array currently in service with the Imperial Navy. Being about three times as long as the current Elusive class Battleship it also has a grand host of hundreds of sensitive hydrophones running down the final seventy-five meters length of steel wire.
It was designed to supplement the AN/BQQ-5 spherical array, and to exceed existent towed arrays. However, the older TB-23 towed array is still in use, being the only short towed array in service with the Imperial Navy.
The AN/SQR-19 Tactical Towed Array SONAR (TACTAS) provides very long-range passive detection of enemy submarines. TACTAS is a long cable full of microphones that is towed about a mile behind the ship. It is towed so far behind the ship so as to not let noise radiating from the shipitself interfere with the noise picked up from targets. Using that noise can determine exactly what ship or submarine is being tracked. The AN/SQR-19B Tactical Array SONAR (TACTAS) is a passive towed array system which provides the ability to detect, classify, and track a large number of submarine contacts at increased ranges. TACTAS is a component sensor of the AN/SQQ-89(V)6 ASW Combat System, and provides significant improvements in passive detection and localization, searching throughout 360 degrees at tactical ship speeds. Processing of complex TACTAS data is performed by the largest computer program assembly ever developed for surface ship anti-submarine warfare.
Meteorology and Oceanography Center Detachment TACTAS support products describe oceanographic and acoustic conditions (using range dependent models) in the prosecution area for towed array ships tasked by CTF-69 for ASW operations. This message is provided when own ship Sonar In-situ Mode Assessment System (SIMAS) or the Mobile Environmental Team’s Mobile Oceanographic Support System MOSS) are not available. It is tailored to the specific towed array carried onboard. The message is transmitted prior to the start of a prosecution and daily thereafter or as requested.
General SONAR Use
Anti-submarine warfare (ASW) usually, but not always, involves the use of sonar. Although the vagaries of the environment make it difficult to predict and use, there is no other type of energy propagation that travels so far in the ocean without significant losses as acoustics waves. In this section, we describe the principles of operation of the major types of sonar systems and one non-acoustic system (MAD). We begin with the system that most closely resembles the operation of basic radar, namely active sonar.
Transmitter. The transmitter generates the outgoing pulse. It determines pulse width, PRF, modulation (optional), and carrier frequency. The output power can be controlled by the operator. The source level may be limited for several reasons. If the transducers are driven with too much power, they can cavitate (drop the pressure so low that the water boils). This is called quenching, and it can destroy the transducer since the normal backpressure is removed when bubbles form on its surface. Since the normal restoring force is gone, the surface of the transducer can travel too far (over-range) and damage itself. The quenching power limit increases with depth due to the increased ambient pressure.
Another common phenomenon that limits the maximum source level is reverberation, which is an echo from the immediate surrounding volume of water. The reverberation level (RL) increases with the source level (SL). At some point the reverberation exceeds the noise level (NL) and will dominate the return signal. Since reverberation always comes back from the same direction you are projecting, the reduction in background noise, quantified by the directivity index (DI) does not apply. When
RL > NL - DI,
the system is said to be reverberation-limited. The figure of merit equation must be modified to reflect this:
FOMactive (reverberation-limited) = SL + TS - RL - DT
When the system becomes reverberation-limited, the display will begin to be dominated by noise near own ship in the direction the active sonar is projecting. The solution is to reduce power to just below the level at which reverberation-limiting occurred.
Transducer array. The individual transducers are simple elements with little or no directionality. They are arranged in an array to improve the directivity index, which improves the figure-of-merit by noise reduction. The array of transducers reduces the beamwidth in the horizontal (or azimuthal) direction, and is usually circular in order to give more or less complete coverage, with the exception of the region directly behind the array (where the ship is). The array is protected from noise by own ship by discontinuing the array in the after regions, and also by putting in sound attenuating material. This region aft of a hull-mounted array, from which the sonar system cannot detect is called the baffles.
The array is also configured to reduce the beamwidth in the vertical direction. Normally a hull-mounted array should only receive sound from the downward direction, not directly ahead, since the noise from the ocean's surface would destroy the sonar's performance.
Beamforming processor. The input/output of each transducer is put through a beamforming processor, which applies time delays or phase shifts to each of the signals in such a way as to create a narrow beam in a particular direction.
The width of the beam formed by the beamforming processor will determine the bearing accuracy of the system when searching. In an identical manner to dual-beam tracking systems, sonar tracking systems can improve on this accuracy tremendously, at the expense of the signal-to-noise ratio.
4.) Duplexer. The duplexer performs the same function in an active sonar as in a radar system, namely to protect the receiver from the full transmitter power while the pulse is going out. It can be thought of a switch that toggles between the transmitter and receiver.
5.) Synchronizer. Performs same role as the synchronizer in radar. Provides overall coordination and timing for the system. Reset the display for each new pulse in order to make range measurements.
6.) Receiver. Collects the received energy. The receiver compares the power level to noise with a threshold SNR (DT) in order to determine if the signal will be displayed in a particular beam. If the DT is set too low, there will many false alarms. If it is too high, some detection capability will be lost.
The receiver may also demodulate the return if frequency modulation is used on transmission. Sonar systems often use pulse compression techniques to improve range resolution.
7.) Display. Puts all of the detection information into a visual format. There are several types:
A-scan: the signal along a single beam for a portion of the listening cycle. A target appears as a raised section if it is in the beam.
Passive SONAR:
Hydrophone array. These are the sensitive elements which detect the acoustic energy emitted from the target. Again, they are arranged into an array to improve the beamwidth. Common configurations are cylindrical or spherical. The cylindrical array operates at a fixed vertical angle, usually downward. The spherical array, which is common on submarines, has a much wider vertical field-of-view. Since the submarine may be below what it is tracking, the array must be able to look upwards to some extent. The large downward angles are only used for bottom bounce detection. Using a beamforming processor (described below) the field-of-view is broken down into individual beams in the vertical and azimuthal directions.
Beamforming processor. Unlike active systems which transmit and receive in a set direction, the passive system must listen to all angles at all times. This requires a very wide beamwidth. At the same time, a narrow beamwidth is required for locating the source and rejecting ambient noise. These two objectives are achieved simultaneously by the passive beamforming processor. The idea is very similar to the active system.
The beams should not be thought of as coming from the individual hydrophones. In fact, each of the beams so created has a narrow beamwidth that comes from the full aperture of the array, not the individual hydrophones.
Broadband display. The output of the beamforming processor is displayed as a bearing time history (BTH):
The newest information is at the top of the display. The beamwidth of the system determines how accurately the bearing can be measured by such a display. A common beamwidth is about 5o. The total amount of time displayed from top to bottom can be controlled (to some extent). A quickly updating display that only kept information for a few minutes would be useful for close contacts whose bearings are changing rapidly. On the other hand, a long tie history is more useful for detecting long range contacts, whose bearings are only changing slowly.
4.) Frequency Analyzer. The frequency analyzer breaks the signal into separate frequencies. This is the spectrum of the signal. For processing purposes, the frequencies are divided into small bands known as frequency bins. The width of each bin is called the analysis bandwidth. Sonar systems can gain considerable signal-to-noise improvements by matching the analysis bandwidth to the bandwidth of narrowband sources. The way to illustrate this is by two counter examples. If the signal processing bandwidth is too wide, then noise from the part of the spectrum beyond the signal is let in and the SNR is degraded. If the bandwidth is too narrow, then part of the signal is excluded, also reducing the SNR. It should be obvious now that the best situation occurs when the bandwidth exactly matches the signal. This is possible when the characteristics of the signal are well known, which they are for most targets.
The frequency analyzer separates (filters) the signal into discrete bins, inside of which the SNR is maximized. The frequency content of the signals from a target information provides vital information about its identity and operation. These frequencies are also subject to the Doppler shift, just like radar, are therefore can provide information about the range rate. This requires that the original frequency be known exactly, which is generally not the case. However, many important facts can be inferred by the changes in the received frequency over time.
Narrowband Display. For a particular beam, the time history of the frequency is called a waterfall display.
This can be used to gain additional information from a contact which is already being tracked by another system. In order to search for contacts on the basis of narrowband information alone requires a different type of display. One possibility is to simultaneously display several different beams, each showing a mini-waterfall display, which are called grams.
These are quite useful, but require great concentration on the part of the operator because there is more information displayed at any one time. Many systems require the operator to systematically search the entire field-of-view, looking at only a few beams at a time.
Variable Depth Sonar (VDS)
Variable depth sonars use large transducers that are towed from the ship on a cable with an adjustable scope. The combination of the buoyancy, ship speed and cable scope determine at the depth that the transducer will be at. VDS is used for two main reasons. At increased depth, the source level (SL) can be increased greatly, since the quenching limit is higher. This is due to increased backpressure on the surface of the transducer. Secondly, the VDS can be operated below the layer.
Recall that the combination of positive over negative sound velocity profiles created a layer at the interface. The layer makes it difficult to propagate sound across it. Therefore, ships using hull-mounted sonar systems will be unable to detect submarines operating below the layer, except possibly at short range. However, if the VDS can be place below layer, the ship can take advantage of the deep sound channel while being in the shadow zone of the submarine's sonar.
ZW-07 Surface Search RADAR
The radar has a peak power of 50 or 60 kW (pulse width 1 microsecond, PRF 1200 pps). There are also a short-pulse mode (0.1 microsecond, 100 kW, can be 2500 pps). Gain is 28 dB; dimensions of the half-cheese antenna are 1.0 x 0.25 m. The beam is 2.4 x 16 deg.
Performance: The range remains at around 200 nautical miles. In the single-pulse mode a ship can be detected at two hundred and ten nautical miles. The ZW-07 radar is installed on the Cartagena SSN.
http://www.dutchsubmarines.com/rd/images/equipm_zw-07.jpg
Inertial Guidance
An inertial navigation system measures the position and attitude of a vehicle by measuring the accelerations and rotations applied to the system's inertial frame. It is widely used because it refers to no real-world item beyond itself. It is therefore immune to jamming and deception. (See relativity and Mach's principle for some background in the physics involved).
An inertial guidance system consists of an inertial navigation system combined with control mechanisms, allowing the path of a vehicle to be controlled according to the position determined by the inertial navigation system. These systems are also referred to as an inertial platform.
INSs have angular and linear accelerometers (for changes in position); some include a gyroscopic element (for maintaining an absolute positional reference).
Angular accelerometers measure how the vehicle is twisting in space. Generally, there's at least one sensor for each of the three axes: pitch (nose up and down), yaw (nose left and right) and roll (clockwise or counterclockwise from the cockpit).
Linear accelerometers measure how the vehicle moves. Since it can move in three axes (up & down, left & right, forward & back), it has a linear accelerometer for each axis.
A computer continually calculates the vehicle's current position. First, for each of six axes, it adds the amount of acceleration over the time to figure the current velocity of each of the six axes. Then it adds the distance moved in each of the six axes to figure the current position.
Inertial guidance is impossible without computers. The desire to use inertial guidance in the minuteman missile and Apollo program drove early attempts to miniaturize computers.
Inertial guidance systems are now usually combined with satellite navigation systems through a digital filtering system. The inertial system provides short term data, while the satellite system corrects accumulated errors of the inertial system.
Schemes
Gyrostabilized platforms
Some systems place the linear accelerometers on a gimballed gyrostabilized platform. The gimbals are a set of three rings, each with a pair of bearings at right angles. They let the platform twist in any rotational axis. There are two gyroscopes (usually) on the platform.
Why do the gyros hold the platform still? Gyroscopes try to twist at right angles to the angle at which they are twisted (an effect called precession). When gyroscopes are mounted at right angles and spin at the same speed, their precessions cancel, and the platform they're on will resist twisting.
This system allowed a vehicle's roll, pitch and yaw angles to be measured directly at the bearings of the gimbals. Relatively simple electronic circuits could add up the linear accelerations, because the directions of the linear accelerometers do not change.
The big disadvantage of this scheme is that it has a lot of precision mechanical parts that are expensive. It also has moving parts that can wear out or jam, and is vulnerable to gimbal lock.
The gudiance system of the Apollo command modules used gyrostabilized platforms, feeding data to the Apollo Guidance Computer
Rate Gyro Systems
Lightweight digital computers permit the system to eliminate the gimbals. This reduces the cost and increases the reliability by eliminating some of the moving parts. Angular accelerometers called "rate gyros" measure how the angular velocity of the vehicle changes. The trigonometry involved is too complex to be accurately performed except by digital electronics.
Laser Gyros
Laser gyros were supposed to eliminate the bearings in the gyroscopes, and thus the last bastion of precision machining and moving parts.
A laser gyro moves laser light in two directions around a circular path. As the vehicle twists, the light has a doppler effect. The different frequencies of light are mixed, and the difference frequency (the beat frequency) is a radio wave whose frequency is supposed to be proportional to the speed of rotation.
In practice, the electromagnetic peaks and valleys of the light lock together. The result is that there's no difference of frequencies, and therefore no measurement.
To unlock the counter-rotating light beams, laser gyros either have independent light paths for the two direction (usually in fiber optic gyros), or the laser gyro is mounted on a sort of audio speaker that rapidly shakes the gyro back and forth to decouple the light waves.
Alas, the shaker is the most accurate, because both light beams use exactly the same path. Thus laser gyros retain moving parts, but they don't move as much.
Brandy Snifter Gyros
If a standing wave is induced in a globular brandy snifter, and then the snifter is tilted, the waves continue in the same plane of movement. They don't tilt with the snifter. This trick is used to measure angles. Instead of brandy snifters, the system uses hollow globes machined from piezoelectric matierals such as quartz. The electrodes to start and sense the waves are evaporated directly onto the quartz.
This system almost has no moving parts, and it's very accurate. It's still expensive, though, because precision ground and polished hollow quartz spheres just aren't cheap.
Quartz Rate Sensors
This system is usually integrated on a silicon chip. It has two mass-balanced quartz tuning forks, arranged "handle-to-handle" so forces cancel. Electrodes of aluminum evaporated on the forks and the underying chip both drive and sense the motion. The system is both manufacturable and inexpensive. Since quartz is dimensionally stable, the system has a good possibility of accuracy.
As the forks are twisted about the axis of the handle, the vibration of the tines tends to continue in the same plane of motion. This motion has to be resisted by electrostatic forces from the electrodes under the tines. By measuring the difference in capacitance between the two tines of a fork, the system can determine the rate of angular motion.
Pendular Accelerometers
The basic accelerometer is just a mass with a ruler attached. The ruler may be an exotic electromagnetic sensor, but it still senses distance. When the vehicle accelerates, the mass moves, and ruler measures the movement. The bad thing about this scheme is that it needs calibrated springs, and springs are nearly impossible to make consistent.
A trickier system is to measure the force needed to keep the mass from moving. In this scheme, there's still a ruler, but whenever the mass moves, an electric coil pulls on the mass, cancelling the motion. The stronger the pull, the more acceleration there is. The bad thing about this is that very high accelerations, say from explosions, impacts or gunfire, can exceed the capacity of the electronics to cancel. The sensor then loses track of where the vehicle is.
Both sorts of accelerometers have been manufactured as integrated micromachinery on silicon chips.
Accelerometer-only Systems
Some systems use four pendular accelerometers to measure all the possible movements and rotations. Usually, these are mounted with the weights in the corners of a tetrahedron. Thus, these are called "tetrahedral inertial platforms", or TIPs.
When the vehicle rolls, the masses on opposite sides will be accelerated in opposite directions. When the vehicle has linear acceleration, the masses are accelerated in the same direction. The computer keeps track.
TIPs are cheap, lightweight and small, especially when they use imicromachined integrated accelerometers. However currently (2002) they are not very accurate. When they're used, they're used in small missiles.
[Photonic Mast]
http://static.howstuffworks.com/gif/photonic-mast-a.jpg
Despite its valued service for more than ten years, the Imperial Navy will soon say "so long" to the conventional periscope. In 2005, construction began on a new breed of attack submarines that won't have a periscope. Instead, these new Cartagena-class submarines will use non-penetrating imaging devices called photonics masts to perform surveillance tasks. Each new submarine will be equipped with two photonics masts, which are basically arrays of high-resolution cameras that capture and send visual images to flat-panel displays in the control room.
[Weapons]
The Cartagena will have eight forward tubes, designed at 500mm width. The tubes will be able to fire virtually any Imperial torpedo design, including the MT-1, MT-2, MT-3 and MT-4. The tubes will also be used to release SSIXS transmission canisters.
Furthermore, the Cartagena is designed with four quadruple cell VLS tubes for a launch sequence of twelve missiles within eight seconds. VLS tubes employed by the Cartagena will be of the same make as those employed on other submersible and surface ships. Meaning, after one missile is launched the entire VLS apparatus uses heavy hydraulics to spin, and in that way while one missile launches another cell restocks, ergo, the VLS tubes never have to stop firing, and instead reload on the move.
The VLS cells are designed to fire Principe III, Shockhound Avenger I and Praetorian V missiles.
The Cartagena can also carry up to two hundred mines and a single Bilbao class UUV.
Finally, the Cartagena wields five retractable ASHUM guns for anti-torpedo defenses.
[Statistics]
Beam: 34 ft.
Length: 377 ft.
Submerged Displacement: 8,100 tons
Submerged Velocity: 28 knots
Crew: 121 Men and Officers
[Cost]
Each Cartagena class SSN will be exported for 1.1 billion USD. Production rights can only be sold to allies for a limited time for 250 billion, on the requirement that at least ten Cartagenas are purchases for full price alongside the order of production rights.