ImageCheeseekau Class Nuclear Powered Ballistic Missile Submarine (SSBN)
Type: Nuclear Powered Ballistic Missile Submarine (SSBN)
Displacement Surfaced: 17,400 tonnes
Displacement submerged: 19,200 tonnes
Length: 170m
Beam: 16m
Propulsion: 1x SSBN10R Pressurized Water Reactor producing 65,000hp, 1x 7 bladed Pumpjet
Speed surfaced: 17 knots (Sprint) 12 knots (Cruise)
Speed submerged: 30+ Knots (Sprint) 23+ knots (cruise), 16 knots silent
Range: Limited to stores, ~ 30 years between refuelings
Test depth: 660m
Max endurance: 90 days
Hull construction: Singled Hulled HY-130 Steel, further subdivided into 4 watertight compartments (Forward, Control, Missile, Engineering). Outer hull maintains a 120mm thick rubber anechoic tile coating.
Crew compliment: 107 Crew
Armament: 8x 660mm Torpedo Tubes (8 + 40 Reloads), 24x Vertical Launch Tubes (3.4m diameter)
Countermeasures: 160 127mm Noisemakers, Advanced Electromagnetic Signature Reduction System
SensorsPAC11 Passive/Active Sonar Array
PAC11 Towed Array
PAC11 Passive Mast Mounted Search Radar
PAC11 Active Mast Mounted Search Radar
PSC11 Telescoping Photonic Masts
Cost:2.8 billion USD
The Cheeseekau Class Nuclear Powered Ballistic Missile Submarine is yet another Export venture by the Philadelphia Shipbuilding Corporation, building on the tremendous export success of the Tecumseh Class Diesel-Electric Attack Submarine and the Tenskwatawa Class Nuclear Fast Attack Submarine, both of which received hundreds of foreign orders. The Cheeseekau Class was based off of the Ohio Classes hull, with tremendous improvements in terms of stealth systems from classes such as the American Seawolf and the Tenskwatawa Class, both of which are Nuclear Powered Fast Attack Submarines, and the Williamson Class Nuclear Missile Submarine, which is the sole ballistic missile submarine in use with the Pennsylvanian Navy today.
Armament & ElectronicsThe Cheeseekau Class’s main armament is its eight 660mm torpedo tubes, capable of firing weapons ranging from Torpedos, like the Mk48 ADCAP, to Anti-shipping missiles such as the UGM-84 Harpoon and the UGM-109 Tomahawk, as well as mines. Alongside of the submarines eight torpedo tubes, there are twenty-four Vertical Launch Tubes along the back of the submarine, just behind the sail. Each of these tubes are 3.4m in diameter, designed to take Submarine Launched Ballistic Missiles such as the American Trident II, or the Pennsylvanian designed UGM-210 “Barracuda” and UGM-240 “Barracuda II”.
The electronics on the submarine are largely the same as found some Pennsylvanian Navy submarines, such as the Williamson Class Nuclear Missile Submarine (SSMN). This includes the same Photonic Mast and the same Sonar Systems, and a similar, but somewhat more compact version of the Radar mast, with a shorter effective range, accounting for the significant difference in size between the Williamson Class and the Tecumseh Class.
The vessel does not utilize a conventional periscope for the Captain or other officers to use in order to identify a vessel. It instead utilizes a Photonic Mast to transmit a digital image of the target from the Mast to a series of High Definition monitors around the control room of the submarine.
A photonics mast (or optronic mast) is a sensor similar in concept to a submarine periscope, except that it doesn't require a periscope tube thus freeing design space during construction and limiting risks of water leakage in the event of damage. A photonics mast replaces the mechanical; line-of-sight viewing system with digital equipment, similar to a digital camera array, and it has fewer locational and dimensional constraints than a traditional periscope.
Unlike a periscope, it need not be located directly above its user, and it requires only a small pressure hull penetration for cabling. This allows the photonics mast to be contained entirely within the sail of the submarine and means the control room need not be placed directly below the sail.
A photonics mast operates by rising above the water similarly to a telescoping car antenna and provides information through an array of sensors, such as high definition low-light and thermo graphic cameras. Images and information can be sent to display panels for analysis. The photonics mast can also support the navigation, electronic warfare, and communications functions of a conventional optical periscope mast.
The submarine utilizes a bow mounted Active and Passive Sonar system as well as a passive cable towed array system, located on the starboard side of the submarine amidships. The Towed arrays cable is almost a kilometer long, allowing it to get clear of noise from the submarine, and to detect other submarines or even surface ships from long distances. The systems are sensitive enough to pick up sounds more than 500km away, though, at these distances, accuracy is anything but good.
Propulsion & HullThe propulsion of the Cheeseekau Class is in its SSBN10R Pressurized Water Reactor, based off of the S9G of the American Virginia Class, and, in some extent, the S6W of the American Seawolf class attack submarines. As a result, the Reactor is capable of pushing the submarine at speeds up to 16 knots while remaining silent, in large part to not only the reactor, but also to the hull design, and the thick coat of anechoic rubber on the outer hull, which, by itself, is capable of reducing the noise output by the submarine anywhere from 4% to 14%. Coupled with the other stealth precautions taken in the design of the submarine, this results in the submarine being quieter at 16 knots than some previous Nuclear Fast Attack Submarines were tied up to a pier.
The submarines hull is constructed primarily out of HY-130 steel, contrary to many designs, which used a lot of Titanium in their design, like the Tecumseh Class Diesel Electric Attack Submarine. HY-130 steel is a very high strength material, originally destined for use in the Seawolf Class Nuclear Fast Attack Submarine. However, the Seawolf ended up instead being constructed of HY-100 steel, instead of HY-130.
The classes hull is further divided into 4 compartments, Forward, which comprises the Submarines Torpedo Room and Bunking, Control, which is made up of the Sonar Room and Control Room, Missile, which contains the Vertical Launch Tubes and related systems, and Engineering, which is made up of everything related to the Nuclear Reactor.
Communication SystemsThe Cheeseekau Classhas a multitude of communications equipment available on it, ranging from Extremely Low Frequency (ELF) and Very Low Frequency (VLF), to satellite equipment for communications through regular Military Communications Satellites.
Electromagnetic waves in the ELF frequency range (3–3000 Hz) can travel through the oceans and reach submarines anywhere. Building an ELF transmitter is a formidable challenge, as they have to work at incredibly long wavelengths: The US Navy's system operated at 76 hertz, the Soviet/Russian system at 82 hertz. The latter corresponds to a wavelength of 3658.5 kilometers. Obviously, the usual half-wavelength dipole antenna cannot be constructed, as it would spread across a large country.
Instead, one has to find an area with very low ground conductivity (a requirement opposite to usual radio transmitter sites), bury two huge electrodes in the ground at different sites, and then feed lines to them from a station in the middle, in the form of wires on poles. Although other separations are possible, 60 kilometers is the distance used by the ZEVS transmitter located near Murmansk. As the ground conductivity is poor, the current between the electrodes will penetrate deep into the Earth, essentially using a large part of the globe as antenna. The antenna length in Republic, Michigan was approximately 52 kilometers (32 miles). The antenna is very inefficient. To drive it, a dedicated power plant seems to be required, although the power emitted as radiation is only a few watts. Its transmission can be received virtually anywhere.
ELF TransmissionThe Extremely low frequency transmission employed was a 64-ary Reed-Solomon, meaning that the alphabet had 64 symbols, each represented by a very long pseudo-random sequence. The entire transmission was then encrypted. The advantages of such a technique are that by correlating multiple transmissions, a message could be completed even with very low signal-to-noise ratios, and because only a very few pseudo-random sequences represented actual message characters, there was a very high probability that if a message was successfully received, it was a valid message (anti-spoofing).
The communication link is one-way. No submarine could have its own ELF transmitter on board, due to the sheer size of such a device. Attempts to design a transmitter which can be immersed in the sea or flown on an aircraft were soon abandoned.
Due to the limited bandwidth, information can only be transmitted very slowly, on the order of a few characters per minute. Thus it is reasonable to assume that the actual messages were mostly generic instructions or requests to establish a different form of two-way communication with the relevant authority.
VLF TransmissionVLF radio waves (3–30 kHz) can penetrate seawater to a depth of approximately 20 meters. Hence a submarine at shallow depth can use these frequencies. A vessel more deeply submerged might use a buoy on a long cable equipped with an antenna. The buoy rises to a few meters below the surface, and may be small enough to remain undetected by enemy sonar / radar.
Due to the low frequency, a VLF broadcast aerial needs to be quite big. In fact, broadcasting sites are usually a few square kilometers (or miles). This of course prevents such aerials being installed on submarines. Submarines only carry a VLF reception aerial, and do not respond on such low frequencies. So a ground-to-submarine VLF broadcast is always a one way broadcast, originating on the ground and received aboard the boat. If two-way communication is needed, the boat must surface and communicate on other, higher, frequencies (such as UHF or VHF).
This band allows for a roughly 300 bit/s transmission - or about 35 8-bit ASCII characters per second (or the equivalence of a sentence every two seconds) - a total of 450 words per minute. Simply shifting to 7-bit ASCII results in a baud rate (characters per second) increase of 14 percent. An additional shift to a 6-bit or a 5-bit code (such as the baudot code) would result in speeds of more than 600 and 700 words per minute. Moreover, as naval jargon is in most cases both very strict and very specific, it is likely to be repetitive and predictable. So a word like "OFFICER" might be broadcast as "OFF." or "OFF1" or simply "OFFI" for example. A word like "COMMANDER" might be spelled as "CMD" and in a similar fashion pairs of words such as "HIGH COMMAND" might be spelled as "HCMD". This kind of specialized naval spelling leads to a further significant reduction of bandwidth usage, allowing for an overall increase in data transmission rates.
ExportThe Cheeseekau Class is only available to nations that are approved by the Pennsylvanian Federal Government. Any denials may be appealed, but usually are final.
Single Unit: $2.8 billion
Domestic Production Rights: $4.2 trillion
Contract: $2.7bn per unit