Akagi-class battleship (FT)

The Akagi-class of heavy space battleships are an Imperial Navy class of multirole battleships. The class is the second-largest line combatant class and the fourth-largest standardised warship class within the Imperial Navy. The Akagi-class is named after the Akagi Mountains on Eienkyo, the Imperial capital planet.

Designed as multi-mission battleships, each Akagi-class battleship is capable of acting as a self-contained battlegroup and controlling large areas of space alone, carrying enough weapons to combat enemy vessels of all classes along with limited fighter carrier capability. Even so, they are often accompanied by escorting battlegroups and specialised warships like carriers during sustained campaigns.

The Akagi-class had a long production run beginning in 180, with 72 in operation today, consisting of 15 Akagi I-class vessels and 57 upgraded Akagi II-class. Of the Akagi II-class vessels, 14 are "Akagi Half" refits from Akagi I to II standard, which lack some structural modifications on the main Akagi II line. 19 Akagi-class ships have been lost in combat, and nine been scrapped. In 230, the Akagi-class production was halted and the class is to be replaced by the more modern and larger Hotaka-class battleships over a 50-year replacement program.

Size and complement
As planned, the Akagi-class vessels are 900 metres long with a height of 487 metres. The wedge shape of the Akagi-class was designed to maximise surface area for the installation of missile cells, as well as to enable multiple angles of fire for the side batteries, though the turret mounts are placed more for broadside-style firing. The vessels are 548 metres wide.

Despite heavy automation and computerisation, the Akagi-class still requires a crew of 5,680 personnel. Amenities for the personnel include three cookhouses, an officer's mess and an enlistee's mess, a sports hall, and two gardens. Typical stores provide enough food and water for two standard months.

Armament and protection
The Akagi-class is equipped with a wide variety of weapons systems for all-range space warfare. 870 multipurpose missile cells are divided into six clusters across the vessels' hull, with four 90-cell clusters located on the sides of the vessels, at forward-starboard, rear-starboard, forward-port, and rear-port positions. One 260-cell cluster is located on the forward dorsal deck, and the final 250-cell cluster is located on the forward ventral deck in front of the forward ventral hangar bay. Each missile cell can be configured to load standardised long-range anti-ship torpedoes or can be partitioned to load a variety of smaller missiles ranging from close-in anti-fighter homing missiles to long-range space-to-surface bombardment cruise missiles.

Fourteen composite anti-ship beam laser arrays are spread across the ship, with four on the starboard side, four on the port side and six on the forward section of the dorsal superstructure. As the class was built, the starboard and port beam lasers were equipped with their own dedicated generator, while the forward-facing arrays drew their power directly from the starship's main reactor. Later mid-life upgrades installed the E-PAC system, where the beam lasers draw power from rechargeable energy banks, saving space by removing the secondary generator and reducing the toll on the ship's main reactor.

The Akagi-class has a large railgun complement for close to medium range combat. Its main battery comprises of eight octuple-mount turrets of 560mm railguns located on the dorsal side of the ship, with four turrets each flanking the dorsal superstructure. Complementing these are twelve triple-mount 155mm railguns mounted in gun ports within the dorsal superstructure, with four each facing port, starboard and forward. Another 50 dual 127mm railgun mounts, also in gun ports, are located across the vessel. 20 each are located on the port and starboard sides of the vessels, and another ten are mounted in a forward-facing battery in the dorsal superstructure.

For close-in protection, 162 triple-25 point defence laser mounts are strategically located, with 44 on the underside of the vessel, 25 each on the port and starboard sides, 30 across the topside of the vessel, and 37 defending the dorsal superstructure. One final point defence laser is mounted at the very front of the vessel's bow. In addition to the lasers, 90 Yamabushi CIWS systems are also installed, with 25 on the underside, 25 on the topside, 10 each on the port and starboard sides and 20 protecting the superstructure and command tower.

Heavy armour protects the Akagi-class, with Nanocrystal Titanium-3 plating covering most of the ship with a minimum thickness of 8.5 metres. Layered above the Titanium-3 plates are ceramic-carbon nanotube composite plates with a 3 metre thickness. A Yukitate Crystal Lattice is also present to protect the ship against energy weapons.

Communications and sensors
Two multipurpose geodesic sensor globes are located atop the bridge tower, housing a vast array of multi-spectrum sensors capable of providing real-time battlefield information and detecting targets and other warships in a sphere around the warship with a diameter of several light-hours. In addition to this, a powerful communications array is also located atop the bridge tower, capable of receiving and transmitting signals several light-years away, using the Ferran Process to boost the signals beyond light speed for instantaneous communications.

Hangar facilities
Dedicated fighter-launch facilities are installed to free up space in the hangar bay, making use of two carousel-conveyor systems to store up to 24 fightercraft and launch all craft within five minutes. The fighter bays are pressurised but intentionally zero-G environments.

The Akagi-class is equipped with three hangars. One is located on the rear of the bridge tower, and is often reserved for use by the commanding officer or VIPs and senior officers due to its proximity to the bridge. The other two hangars are located on the ventral surface of the vessels. A smaller service hangar is located closer to the bow of the vessel, and is mainly used to load personnel, equipment and for resupply. The largest hangar is located in the middle of the ship, directly ahead of the reactor bulge, and is the primary means of embarking personnel and stores into the vessels.

For combat operations, Akagi-class vessels typically carry a squadron of 24 fighter craft for defensive screening purposes. Eleven shuttles or other utility craft are also carried aboard, though there is enough space for over twenty shuttles within the main hangar.

Drone perches can easily be attached to the outside of Akagi-class battleships, allowing them to carry even more fighter support if required.

Powerplant and propulsion
A Fujikawa Revision 7 Capital Fusion Reactor was developed for the Akagi-class battleships when they were first built. Oversized with an extremely large output, the Revision 7 set a new standard for starship fusion reactors and is five times larger than Fujikawa's Revision 6, requiring an armoured bulge to be constructed on the ventral side of the warships to accommodate the size of the reactors. These not only provided electrical power for the ship, but also powered the ship's main means of propulsion. Three large Fujikawa Kanhon-1 ion engines provide main thrust, while four smaller Sasebo NORIKYO-4 ion engines provide steering and additional thrust as needed. Spread across the hull are arrays of tiny ion thrusters that are needed for directional control.

Following the 230 mid-life upgrade package, the Revision 7 reactor was replaced with the more advanced Revision 8 fusion reactor, which is slightly smaller and more efficient. Around 60% of the fleet has received this upgrade.

For faster-than-light travel, a Takaoka HaGe-34 Extended Leap drive is installed.

History
Production of Akagi-class stopped in 225. They were making about two a year. Then the Second Hyperpower War broke out and production started again on Akagi II vessels. Then production stopped again in 230, with the focus shifted to refitting the ships damaged in the war into Akagi II vessels.

Design and construction
The Akagi-class was a product of the Year 200 Fleet Upgrading Programme. Initially an upgrade program for the Kamikokuryo-class battleships, the plan eventually developed into an entirely new type of warship following the decision to eventually begin scrapping the ageing Kamikokuryo-class battleships by 210.

Designated Project Fugaku-56, the new battleship concept quickly took shape under the Imperial Navy Tactical Research Division and a civilian team of Sasebo Military Systems' top designers, led by famous starship designer Ikuta Risa. The "flying bridges" and various structures on the superstructure of the Kamikokuryo-class were flattened to one solid superstructure on the dorsal surface of the warship, though the tall command tower was retained, becoming the iconic T-tower that would come to define many Imperial warships of the new century.

As more and more weapons were piled into the design by the Imperial Navy's ever-changing demands, the power requirements of the warship increased, necessitating a much larger reactor. Subcontracted to develop the reactor, Fujikawa Corporation created the Revision 7 Capital Fusion Reactor. It was determined that in order to fit this new reactor, as well as the large amount of weapons needed, the warship would have to be almost two kilometres long. At this point in the Empire's history, only supercarriers were this large, with most multi-kilometre ships only civilian supertankers. It was finally decided that the Fugaku-56 would be capped at 1.6 kilometres long, with the reactor taking up a large amount of space within the dorsal superstructure and protruding from the ventral side, with a heavily-armoured dome covering the ventral portion.

It was hoped that these new super-battleships would be well-armed enough and so imposing they could replace entire formations of ships, carrying the firepower of entire squadrons of Kamikokuryo-class battleships. After five years of development, the first Fugaku-56 battleship was laid down in the Shirada Orbital Array shipyards in 195. Construction of the first vessel took three years due to a lack of then-considered super-large drydocks and specialised equipment for such a large project, though subsequent ship construction would increase in speed as these large ships became the new normal. The sudden outbreak of the Empire-Alvium War in 197 further delayed the tail end of construction, though construction was rushed upon the conclusion of the Empire-Alvium War. Upon launch in Hachigatsu 198, Empress Momiji named the vessel and its class Akagi.

In an attempt to prevent panic and an arms race amongst the human community, the Akagi-class battleships were classified as "heavy battleships", though in the era they were closer to a type of super-dreadnought compared to existing designs. Almost immediately, the titanic Akagi-class made waves across the Human Sphere, drawing the curtain on the old era of rapidly manoeuvrable space warfare between combined-arms squadrons of fast-moving, specialised warships and ushering in a new era of mighty glaciers which carried a wide variety of heavy weapons themselves. In the new era of large-scale warships that the Akagi-class brought, the Kamikokuryo-class that had served the Empire well in its first major war could arguably have been reclassified as a light cruiser, but retained its classification as a formality.

Service
The first public unveiling of the Akagi-class battleship was during the Revolution Day fleet review in 198, when the lead ship, Akagi, led the Imperial Navy's parade contingent. The Interstellar Union of Revolutionary States immediately began working on a new ultra-range anti-ship missile in a bid to maintain parity during this period, which was the height of the Second Cold War. As part of the Imperial Navy's propaganda effort, Akagi was deployed in numerous high-profile combat incidents against pirates and insurgents, where it quickly attained a reputation as an unstoppable warship with the armament of an entire squadron. Akagi was subsequently made the flagship of the Imperial Navy, cementing the vessel's place as the symbol of Imperial space power. Akagi-class battleships soon became the mainstay of the Imperial Navy, with all older battleships retired to prevent cost overruns.

In the usual Imperial element-level tactical doctrine, the battleship is appreciated as the most well-armoured and armed vessel in the element, with all other vessels operating to support and utilise the advantage provided by the battleship. Tactics include utilising the battleship as a decoy for flanking attacks by cruisers and destroyers, using the battleship as the core of a frontal assault, using the battleship's artillery to support advances by the cruisers, and more.

Replacement
The Imperial Navy began searching for a successor to the Akagi-class in 225. A design competition for the Next Generation Battleship was carried out with emphasis placed on three areas; increasing hangar space to increase versatility, improving general survivability for the crew, and increased ship-to-ship combat capabilities. Akagi-class production was halted in 226, but it was determined that production would resume if no satisfactory design emerged from the Next Generation Battleship programme. At one point in the design cycle, the visual appearance of the vessel and its ability to supplant the Akagi-class as a symbol of the Empire was also of serious consideration.

Ultimately, the Hotaka-class battleship was approved as the successor the Akagi-class. Boasting almost twice the length of the Akagi-class, the Hotaka-class has expanded hangar facilities as well as almost thrice the weapons options of the Akagi-class. Construction of the Hotaka-class began in 231, with the first Hotaka-class battleships joining the fleet in 235. The Akagi-class remains in wide use, however, and there are no plans to begin scrapping the fleet.