Autumn-class cruiser

The Autumn-class cruiser is a general-purpose capital ship manufactured by SinoViet Heavy Machinery for the UNSC Navy.

Development and construction
The Autumn-class cruiser was a co-project initiated when SinoViet Heavy Machinery's Reach branch was given the contract to refit the aging, the UNSC Pillar of Autumn, with the necessary capabilities to undertake Operation: RED FLAG. While this process was underway, they took the opportunity to study its construction to not only allow for other surviving vessels to receive the same improvements at some point, but also to document many of the Reyes-McLees Corporation's trade secrets present in its design. A copy of the design was then experimented with and improved by SinoViet engineers based on feedback from the refit program, and previous experience with work on the second generation of Halcyon-class cruisers. By 2552, the ship known in-house as the Flight IV Halcyon bore little to its peers, with its hull being completely refurbished and streamlined to ease fabrication.

Following the ceasefire of March 2553, SinoViet submitted the modified design to the UNSC Department of Naval Construction as a candidate for a new classification of cruiser, and would be first company to submit any warship design after the Great War. Initially, they found the submitted plans wanting, disappointed that it did not integrate any of the technologies they wished to move forward with - for example, anti-plasma countermeasures, Series-VI CODENs for slipspace drives, and reversed-engineered Covenant components. Rather than abandon it, SinoViet's suggestion to use the ships as a stopgap model to bolster the UNSC's fleet prior to the deployment of next-generation cruisers was taken into consideration. This was accepted, as analysts predicted even the first of the new submissions developed by Reyes-McLees could not enter service until 2565 at the earliest; meanwhile, SinoViet claimed that their new cruisers, christened the Autumn-class, could be commissioned by 2556. This ensured that the UNSC would have brand-new ships launched immediately after the last entered service.

One of the more controversial elements was SinoViet's decision to scrap the Halcyon-class cruisers and build the new Autumn-class from scratch. This process bypassed the expensive partial-disassembly and gutting process that was required to refit massive changes such as new reactors and power transmission network. It also allowed all new ships to be built near-identically to one-another, allowing the entire line to be upgraded with the exact same improvements using the same installation techniques; indeed, a number of cruisers were refitted immediately after being commissioned. Certain components and structural bracing were recycled for the Autumn-class, but these were not added to the first four ships.

History
Following their commissioning, Autumn-class cruisers were immediately inducted into the various fleets that participated in Operation: HIGH TIDE, the UNSC Navy's large-scale campaign to reclaim the Human Sphere from the various warlords that emerged following the Covenant's fragmentation. They were first assigned to vanguard formations, where those led by an Autumn were able to not only commit to strikes further away from secured space thanks to their state-of-the-art slipspace drives, but also proved a more even match for ex-Covenant cruisers. Indeed, their introduction marked a turning point in the operation, towards a period where UNSC admirals became more confident in their ability to defeat warlord armadas in a straightforward engagement - a fact reflected in HIGH TIDE's escalating success.

Role
In purpose, the Autumn-class cruiser is supposed to act as an adaptable, well-balanced capital ship, able to conduct a number of different missions within a very short span of time. This can include going from escorting a convoy of relief ships, to coordinating an attack against a Covenant remnant fleet, to undertaking high-endurance missions far away from Human Space. This is mainly achieved through the use of prefabricated mission packages, which allows a single ship to be rapidly optimized to a specific objective in a very short span of time.

However, the bread-and-butter of this class is in a specific set of roles. The Autumn-class cruiser is primarily intended to combat other Covenant capital ships, where its durability and use of modern weapons allows it to engage them on a much more even playing field. In these engagements, it is supposed to draw their fire and survive the punishment, allowing the rest of the fleet a chance to outmaneuver and overwhelm their opponents. This lends it well to an attack or escort role, where in the former it is not uncommon for a pair of cruisers to propel themselves into an enemy formation to disrupt their lines and temporarily break their cohesion. The Autumn-class works well as a squadron flagship, where its potent counter-jamming suite and native flag deck allows it to effectively lead groups of smaller craft into battle. In these cases, it can piggy-back older ships through slipspace, moving them far further than they otherwise could on their older translight engines, and carry a surplus of fuel, spare parts, and even vehicles and cryofrozen crewmen for extended missions. However, it is generally acknowledged that a dedicated replenishment ship can fulfil this need, without the risk of exposing itself to Covenant weaponry. It can also operate as a light carrier for small task forces, although these hangar bays are typically used to ferry ground forces instead.

Weaknesses and counter-tactics
As the last classification of cruiser that was based on shipbuilding policies spanning all the way back to the UNSC's founding four centuries prior, the Autumn-class has many outdated design considerations that are not shared by its later contemporaries. The first major weakness is its exposed bridge mounted on its frontal surface, which was required by regulations at the time so the command staff can maintain situational awareness even when sensors are offline. This feature means that its possible for a single lucky hit from a bomber or warship to wipe out the entire command staff. In addition, the cutouts in the engine cowling and midsection, used for both radiating heat and reducing mass, are not as well armored as the outer hull. One last design weakness is that the naval coilguns and point defense guns have a blind-spot on the cruiser's aft, and while it is armored, significant damage can still be caused to its fusion drives. Any missiles or plasma torpedoes launched in this spot can sail without worry through the Autumn 's active defense systems, potentially reducing the cruiser's ability to accelerate. Fortunately, its old design principles means that it still retains a large payload of missiles to protect itself from all directions, an advantage over newer cruisers that maximize their naval coilgun complement instead. However, this does mean that ships or units with a large anti-missile complement can eliminate a sizable portion of the cruiser's firepower.

If engaged, many savvy ex-Covenant shipmasters have exploited the Autumn-class' lack of aft-mounted weapons to assault it from behind, where they only its Archer missile pods are able to engage them. In direct combat, it has been observed that many opponents will close the distance and get out of the cruiser's forward arc, either maneuvering to the broadside or a high side-angle so the Spitfire batteries near the aft have trouble turning to fire on them.

Configurations
Unlike the Halcyon-class cruisers that preceded it, the Autumn-class cruiser is built with a somewhat less-durable but more modular design. All across the starship are a large number of empty storerooms, maintenance airlocks, and power connection sockets that are organized in a standardized orientation, which allows SinoViet to quickly and easily fit the infrastructure for extended components. New weapon systems, self-defense arrays, and even mission-specific hardware can be effortlessly installed and reconfigured at any given naval base. Because of this, the Autumn-class has a number of specialized configurations that differ in firepower, carrying capacity, and supportive abilities.


 * Orbital assault/strike: Widely considered the 'vanilla' configuration, the orbital assault/strike set-up is designed to maximize the cruiser's forward firepower and deploy a fast, hard-hitting ground element. The four twin-mount Mark 40 Spitfires are positioned directly in front of the secondary fusion drives in pairs, which allows them to collectively target a single ship, but restricts their fields of fire. The hangar has been retooled to support the launch of ten D82-EST Darters and up to twelve gunships, as well as allocating space for additional blast-protected munitions storage for both its ODSTs and aerial wing. The micro-satellite and reconnaissance drone complement has also doubled.
 * Escort: Another common sight, these cruisers are used when they are likely to confront massed hostiles or better protect a nearby ally. The Spitfires are better spaced around the ship to provide better firing arcs, and a total of twenty-four quad M870 Rampart point defense guns are there to protect the mothership from missiles. Two squadrons of C712 Longsword, as well as an assortment of other space fighters, are typically carried at the cost of its ground complement.
 * Attack: Based upon the original specifications for the Pillar of Autumn, the attack version is designed to vastly augment the cruiser's firepower. Four more twin Spitfire turrets, eighteen M910 Rampart quad-turrets and cells for heavy missiles such as Bident missiles are installed. Later on, Spitfires in triple-mounts are not uncommon sights on these ships. To protect itself, two shield generators and an assortment of Universal Countermeasure and Decoy Launchers can be activated at a moment's notice. The MAC may be upgraded with additional slug storage and multi-shot capability, although both of these will cut into its hangar storage.

Defenses and countermeasures
The Autumn-class cruiser saw a wide variety of changes to its defensive systems, as new protective techniques and advanced components were introduced over the course of its service lifespan. However, a few systems had endured throughout their history. Their primary protection always came from large sheets of titanium-A3 battleplate, an improved, restructured armor plate that is now equally effective at resisting energy-based weaponry such as plasma as well as kinetic penetrators and high-explosive warheads. This had been structured in layers separated by insulating cages of Reinforced Carbon-Carbon, decreasing mass while also limiting thermal intrusion to the plates above this layer. These gaps are also necessary to the electromagnetic armor setup used in the upper layers of the hull, further resisting efforts to breach it. To jam, lure away, or repel incoming attacks, there are dozens of M492 Cyclone countermeasure launchers on a turreted base, which can select between a wide variety of active and passive-defense munitions to improve survivability. This includes everything from ionized gas canisters to break sensor locks (on certain regions, or all over the ship), to self-guided flares, to much later energy-shield barriers. The AN/SLQ-83(V) magnetic shield was also fitted, which used the cruiser's MAC to project a directed magnetic field all around it, which temporarily acts as a serious obstacle to plasma-based weapons. Should it receive a hull breach, a complicated series of blast doors, emergency venting, expanding fluid seals, internal armor, and compartmentalized atmosphere control - all measures taken from the Halcyon-class - ensure that the Autumn-class is just as resilient against penetrating impacts.

This already-comprehensive protection scheme was quickly improved in the years to come after its introduction. One of the earliest changes was the integration of a refractive coating to the top layer of the hull, a gel based on those used by Covenant soldiers to protect them from energy weapons. Although it had been used by the UNSC Navy since the late 2530s, it only started to be rolled out to the rest of the fleet by the end of the 2550s. Next would come the shielded plating, which used miniaturized shield generators to project a localized barrier around the point of impact. While significantly cheaper and put less strain on the host's powerplant compared to a full-scaled model, the initial reactive nature of the system meant that it can only block shots that come after the hull is hit, and it was discovered to increase the yield of high-explosive warheads that were detonated after the barrier was triggered.

Armament
The Autumn-class cruiser's main armament is a single spinal-mounted Mark IX, heavy coil - 45J3D3 Magnetic Accelerator Cannon, which is intended for use against large, slow-moving targets. It is more powerful and longer-ranged than any other MAC previously fitted to a cruiser, thanks to a hyperdense concentration of magnetic coils in the barrel. These are paired with a comprehensive fire control system, which is able to be tweaked by the crew to emphasis a specific area of its performance, such as limiting the velocity of individual shots in exchange for a high rate-of-fire. To future-proof the design, the Mark IX is engineered in such a way to make the installation of upgrades a straightforward manner when they become available. While a formidable weapon by itself, the barrage from an Autumn is not as destructive as its predecessors, as they are fitted with twin MACs instead.

To complement it, 768 M58 Archer missiles are intended to be carried on each mission, with 24 missiles allocated to each of the 32 pods. Five fast-reloading silos are built into each pod, which allows the Autumn-class to fire a combined volley of up to 160 Archers at once. Although they are falling from prominence in newer ship designs, M58 Archers fulfill a versatile niche in the cruiser's armament for a number of reasons. Their guided nature allows them to cover all regions around the ship, while it is suitable against both large warships and small fighters thanks to its high maneuverability. They are able to provide cover for any heavy missiles and nuclear weapons that are deployed, where they overwhelm point-defenses through sheer force of numbers.

Four twin Mark 40 Spitfire 700mm/35 cal naval coilguns were fitted as standard on Autumn-class cruisers, which were intended as its main battery weapons. Like the older Mark 33s they replaced, the new generation of Spitfires were used to directly engage other capital ships at medium ranges. Denser electromagnetic coils increased the muzzle velocity of their shells, and larger shells gave the Mark 40s a heavier punch and longer reach. In their standard placement, all four turrets could concentrate their fire on the cruiser's forward arc, greatly increasing the damage these cruisers can dish out when on the offensive.

The cruiser's anti-aircraft defense were lacking compared to previous models of capital ships. Six twin-linked M74 Sentry 330mm/30 cal naval autocannonss were included for use against both light warships such as corvettes and frigates, and space fighters. In addition, six quad M910 Rampart 105mm/45 cal point defense guns were fitted to protect against both space fighters and missiles. Combined, both systems could protect every direction of the Autumn-class, but the density of fire was too limited to deter even the lightest fighter attack. This was largely down to shortages that occurred immediately following the war, although by the mid-2560s their anti-aircraft suite would be upgraded to address this.

Mounted in axial silos, although not always carried due to their scarcity, were four Shiva-class nuclear missiles. Large and verging on obsolescence by the end of the Human-Covenant War, Shivas normally had 30-megaton vacuum-enhanced warheads, which could deal deal considerable damage to Covenant cruisers. However, their main use was to impair their combat capabilities by releasing a massive electromagnetic pulse; while larger capital ships were hardened against their effects, smaller frigates and destroyers suffered from power limitations and reduced effectiveness with their weapons and shielding. Because of this, they were prime targets for enemy point defense, and needed to be covered by a swarm of Archer missiles if they had any hope of reaching their targets.

Propulsion and powerplant
The Autumn-class cruiser was powered by a single CDT1-H fusion reactor, a unique powerplant that was heavily inspired by the upgraded set applied to the UNSC Pillar of Autumn. Manufactured by Naoto Technologies, and fed by deuterium-tritium fusion, it was composed of a single large reactor surrounded by two smaller ones. This arrangement allowed their magnetic fields to overlap with each other, which can boost reactor output to over 300% capacity. All three fusion cores were slightly larger and more efficient than those used on the refitted Halcyon, and upon launch only 75% of their output was being used. The first Autumn-class cruisers were fitted for, but not with, the advanced chilled-ion cooling system. These were fitted at a later date, which virtually eliminated any concern of a reactor meltdown.

In the event of complete reactor failure, sixteen racks of four BL81 emergency batteries were fitted. Continuously charged from the reactors, these could provide enough power to run the cruiser at minimal status for up to twelve hours. This was to give enough time for one of the secondary reactors to be repaired and brought back online. After that point, a second set of batteries would switch on to maintain the emergency lights, life support, and the point defense guns for up to 72 hours.

The Autumn-class cruiser had a wealth of propulsion systems. It was mainly pushed through space on two Boglin Fields' Starfire-V fusion drives, and eight Naoto Technologies V9/M-FR fusion drives arranged around them. These were fast enough to enable it to match speeds with the much lighter Marathon-class, and this could be increased further with eight powerful but fuel-hungry fusion rockets. Like the Halcyon-class, on either side of the bow were two rotating mounts for three smaller fusion rockets. These were intended to more quickly steer the cruiser onto a new course, and could be replaced if needed with dedicated missile pods. A total of 48 Sprinter-91 maneuvering pods were installed for minor course corrections.