Behold! My first proper(ish) full write-up. (Ironically, most of the information here would be highly classified.)
They probably look mostly like a smaller
Seawolf.
Uinen-class hunter-killer attack submarine (SSN):- Length: 320 ft / 97.5m, Beam: 36 ft / 10.97m
- Cost: $2-2.8 billion
- Number of Vessels: 30 building or in service (ongoing construction program)
- Designed/Introduced: early 2010s
- Power/Propulsion: nuclear reactor, lithium-ion batteries, pump-jet propulsor
- Speed: >30 kts submerged (actually 35 kts)
- Range: unlimited (nuclear)
- Test Depth: officially 800+ ft / 243.8m (actually ~1800 ft / 548.6m, with crush depth 2700+ ft / 823m)
- Crew: ~70
- Armament:
- 6 x 26” torpedo tubes (26 weapon racks; typical loadout 20 x Mk 48 torpedoes, 6 x 21” MOSS decoys)
- 2 x 7-cell VLS silos
- 13 x UGM-111 Fëanar (stealthy long-range anti-ship and land attack cruise missile), or UGM-109 Tomahawk
- 4 x IDAS SAM (1 cell)
- 1 or both silos can be fitted with either a lock-out chamber for special forces, or a swimmer delivery vehicle (if those can be carried vertically and travel horizontally) in place of missiles
The
Uinen (pronounced oo-ee-nen) is the newest class of vessel in service with the Mitheldalondian Navy. Unlike the previous multi-purpose
Ossë-class guided missile attack submarines introduced in the 1990s, the
Uinen is a dedicated hunter-killer, intended to hunt down and destroy high performance enemy submarines.
The design program was initiated in response to the increasingly widespread proliferation of advanced diesel-electric boats with air-independent propulsion, and the introduction by several other nations of advanced nuclear submarine programs. (Or because I watched too much Cold Waters gameplay on YouTube and slightly freaked out at how easily modern subs run around massacring everything in sight without even being detected.) The impressive stealth capabilities of small, affordable AIP diesel boats were of particular concern to the Navy, which worried that Mitheldalond's then-existing ASW measures would be inadequate to protect carrier groups from such threats. Thus, the Navy initiated a new program aimed at drastically improving Mitheldalond's ASW capabilities. Among other changes, this program called for a new, cheaper frigate with enhanced anti-submarine performance (the new
Elwing-class frigate), and a new attack submarine which would be capable of detecting and sinking even the quietest modern subs before they could get close enough to threaten a carrier group, without being detected itself. This would become the
Uinen-class.
In regards to the
Uinens' stealth characteristics, the Navy - which generally deliberately understates the abilities of their ships, at least with regards to their true specifications - has described them as "quieter than a Seawolf", "second to none", and more conservatively as "easily one of the quietest submarines ever built" in various press releases. The boats are built of high strength non-magnetic steel, which makes them difficult to detect with magnetic anomaly detectors and unlikely to set off magnetic mines. The outer hull is as smooth and as free of protrusions (which would disturb the flow of water) as possible. The sail is blended smoothly into the hull, eliminating any sharp transitions and further smoothing the flow of water. Thick anechoic tiling covers the exterior hull, while the interior is fitted with extensive soundproofing. All machinery and moving components are mounted on vibration-absorbing rubber pads, and the decks are lined with no-slip rubber matting designed to muffle the sound of footsteps.
They are fitted with an advanced pump-jet propulsor featuring a composite multi-material rotor, which is said to virtually eliminate cavitation. This allows the
Uinen to achieve higher speeds more quietly than other submarines at any given depth. X-form stern planes allow them to operate in shallower water than would be possible with a conventional vertical rudder arrangement, and enable them to rest on the seabed without damaging the rudder. They can also be made smaller than the usual cruciform planes without sacrificing maneuverability. This makes them quieter, as smaller planes both produce less drag and require smaller motors to actuate them. Thus, the use of X-form stern planes increases both the
Uinens' maneuverability and stealth.
The need to constantly circulate reactor coolant is a major source of noise on even the quietest nuclear submarines, and is one of the main reasons it's considered possible to make an AIP-equipped diesel-electric boat quieter than a nuclear one. The
Uinen is one of only a handful of nuclear submarines that have the ability to operate with their reactor pumps secured (turned off). When this is done, the only moving parts left to produce sound are the propeller shaft and motor, making them quieter than many AIP boats, which often have additional moving parts (Stirling engines for example). However, this can only be done for a short time before the reactor is in danger of overheating. The
Uinen-class solves this problem by reducing reactor output to the minimum level necessary to sustain the reaction (they could just shut down the reactor completely, but this runs the risk - however slight - of not being able to restart the reactor, so it's rarely done). This dramatically reduces the amount of heat produced, which allows the
Uinens to operate significantly longer with pumps secured, or to circulate coolant much more slowly and quietly. When operating in this mode, the boats run entirely on battery power. They use lithium-ion batteries - which have a much higher capacity than the older lead-acid types - and carry an unusually large number of cells for a nuclear boat, allowing for up to three days of operations at a speed of around 5 knots. Unlike diesel-electric subs, an
Uinen does not have to surface to recharge her batteries; she simply has to increase her reactor output to normal levels.
The
Uinen-class makes extensive use of advanced active noise and vibration cancellation technology. Arrays of microphones and speakers are strategically placed around the hull, and at key areas that produce the most noise. Such locations include in the pump-jet shroud, where the propeller shaft exits the hull, and around other moving components. As with other active noise cancellation technologies, these systems are best suited to cancelling out continuous, periodic sounds like the hum of electric motors and pumps, the circulation of coolant for the reactor, the sound of the propulsor as it moves through the water, the spinning propeller shaft and bearings, and the interaction of the hull with the water around it. However, the
Uinen can also cancel out more sudden sounds with known acoustic signatures, like the opening and closing of torpedo tubes and missile hatches, the flooding or emptying of ballast tanks and torpedo tubes, and the motion of the bow and stern planes. Her systems may also attempt to cancel out unexpected random sounds such as objects falling or being dropped within the sub, or even active sonar pings from other vessels, but this is significantly more difficult, as such sounds would have to be detected, analyzed, and replicated (in reciprocal) almost instantly for noise cancellation to be truly effective. Other systems are present which detect vibrations originating from within the submarine and act to counteract them at the outer hull, preventing them from being transmitted into the surrounding water as sound. Precise timing is required for all of these operations to be effective.
Additionally, the
Uinen-class has multiple electromagnets positioned around the hull that actively counteract their already small magnetic signature, rendering them almost immune to magnetic anomaly detectors and magnetic mines. Excess heat is channeled out the bottom of the hull, and the boats are equipped with active temperature control systems. This cuts down on any IR signature that might be detectable by aircraft or surface platforms.
In addition to their extreme stealth, the
Uinen-class carries a wide array of highly capable, highly sensitive sonar arrays, including a large diameter spherical bow sonar, side-mounted wide-aperture arrays, an aft-looking array mounted in the sail, and variable depth high and low frequency towed arrays. These systems were all designed to detect high performance nuclear and AIP diesel-electric submarines. Even so,
Uinen-class boats have reported difficulty detecting and tracking each other in exercises.