Rhea-class battlecruiser

## *Rhea* class

The ***Rhea*-class cruiser/carriers**, also known simply as ***Rhea*-class battlecruisers** or as ***Rhea*-class light carriers**, and sometimes as ***Sylvia*-class heavy cruisers**, are a series of heavily armed and versatile warships produced in the first half of the 2500s for the Terran Alliance Navy. Designed for the rigors of frontier and colonial service, freeing up valuable *Luna*-class cruisers for fleet work, as well as elderly and worn-out *Mercury*-class starships for refit, upgrade, and repair.

Despite their initial development being exclusively frontier-oriented, many of these ships would be pressed into general fleet service due to their excellent qualities.

## Design

### Design History

Developed alongside the contemporary *Cyllene*-class "pocket battleships" as a more cost-efficient alternative to continuously deploying *Luna*-class and *Mercury*-class fleet cruisers on patrol duties, as well as freeing up *Venus*-class battlecarriers for more pressing duties, the *Rhea* class initially envisioned as a ship not all that different from an enlarged *Deimos*: the extra space would be taken up primarily by additional crew quarters and manufactories for her own repairs, along with an improved hangar arrangement. As the *Cyllene*s grew, however, so did the *Rhea*s: developments concerning the latest Iktharan warships alongside the deteriorating international situation merited a ship which could hold its own in the kind of 'penny packet' fighting that was increasingly being fought on the frontiers.

Accordingly, the *Rhea* class suffered a complete redesign: the plans for an enlarged *Deimos* were dropped, new requirements instead stemming from multiple 'experimental' battlecruisers and battleships then building or working up, including *Belladonna* and *Achilles*. New developments and substitution of the 'standard' engines for more compact models saved valuable mass, bringing the ship's cost down to just only slightly above that of a heavy cruiser, despite the severe size and firepower difference.

### Dimensions & Role

At exactly one kilometre in length, the *Rhea* battlecruisers were no longer than the old *Mercury* models they were intended to replace: substantial mass savings, however, allowed them better maneuverability than even that venerable type. They largely resembled *Achilles*: a single-hull configuration was adopted to reduce costs and save mass, while the four main engines were located in two distinct pods to either side - partially sunk into the hull - in a stacked arrangement aft. Ramjets located on the front of these pods allowed for the engines to be used in an atmosphere: normally shuttered by heavy armoured panels, they made the *Rhea*s capable of high-altitude operations in an atmosphere.

As with other Alliance battlecruisers, the *Rhea* class served both traditional 'fleet' work as a battle scout and as a flagship to smaller groups on the tactical level: heavily armoured, she could also act as a battleship in a pinch, especially on the frontier's fringes where small outbursts of fighting between squadrons was common, especially against the Iktharans.

### Power & Propulsion

As with most other modern Alliance starships, the *Rhea* class were designed to use a **reaction core**: a substitute for all of the cold fusion and matter/antimatter annihilation reactors used up to that time, it was an Alliance derivative of the Lucaelian **ionization reactor**, an artificially sustained miniature star encased in a Dyson sphere. As these ships were not intended to use nearly the same power as an *Iapetus*-class battleship, the size of these cores could be reduced significantly- a side effect was that they were also more fuel-efficient, burning less than half the hydrogen and antimatter supplies of previous, larger models.

The high acceleration of this type was obtained by a pair of plasma impulse thrusters: while the lower pair of ion drives were used for cruising, greatly reducing propellant consumption compared to the old *Mercury* class, the upper pair of plasma drives could be used in combat to obtain maximum thrust. Although less fuel-efficient at maximum power than a homogenous grouping of ion drives, the arrangement considerably improved overall operating endurance- more than 70% greater efficiency under normal conditions was theorized based on data analysis of serving ships, while still producing much higher power than a standard ion-only engine setup in combat.

Maneuverability was provided by a mix of ion and plasma vents: the former could be used for 'normal' maneuvers, while the latter were emergency thrusters for combat usage or in times of danger.

### Artillery

The *Rhea* class were far more substantially armed than the ships they were intended to replace: though they lacked the boring laser found in almost all modern Alliance capital ships, they could devote far more power to their main batteries as a result. This came in the form of eighteen 380-megaton laser cannons: capable of unleashing more firepower in a single volley than a full century of nuclear testing on pre-starflight Earth, they were mounted in four twin turrets and ten fixed-forward gunports on the angular prow. Advances in beam collimation chamber miniaturization allowed for the size of the turrets to be significantly reduced, allowing the *Rhea*s to carry two dorsally and two ventrally on the centreline.

Secondary armament was comprehensive: the 'dual-purpose' gun was finding credence in the Alliance at this time, allowing the *Rhea* battlecruisers to sport over two dozen 12.5-megaton laser cannons in single/twin-mounts, strewn across the hull in a mix of disappearing mounts and casemates. Handier than the older, heavier 15-megaton weapon while considerably more powerful than the 10.5-kiloton gun, they were considered a good mix between the two.

Point-defense armament was handled by a comprehensive battery of medium- and small-calibre laser cannons: 'snapper balls' - so-called because they could snap a crewman from their seat if their harness was incorrectly secured - had been a mainstay of the Alliance's fleet for two generations of warships at this point. Adding to these were several pintle-mounted railguns firing explosive shells for ballistic defense- unlike lasers, these did not have to hit the target to potentially destroy it, as well as being better shield penetrators.

Additional armament came in the form of over a hundred vertical cells for isokinetic missiles: a new development within the Alliance, they were a variable-payload warhead mated to a small but impressively fast body. Though still unable to pierce conventional point defenses without being launched *en masse*, they were considered twice as likely to reach the target without being shot down. As each cell could be reloaded internally and was normally quad-packed, a *Rhea* could unleash a truly massive salvo to devastate any opponent within range.

### Complement

Part of the *Rhea*'s lack of a superlaser was due to their extensive hangar facilities: as they were intended to supplement and replace the *Mercury* in all relevant roles, this included acting as a light carrier. The 'standard' loading included I-1 *Poniard* interceptors and MR-2 *Rapier* starfighters in significant numbers: in recognition of the lack of a real need for a 'strike' loadout, no bombers were normally provided, though they could be carried when acting in a larger fleet.

### Protective Systems

As with all Terran battlecruisers, the *Rhea* class was considerably better-protected than what the type would suggest: though thinner-skinned than most modern Alliance starships, to the point where they would be criticized as "effectively unarmoured", they were actually extremely resilient in the face of enemy fire and battle damage. A twelve-layer 'sandwich' construction of classified monocrystalline metals and foam ceramic composites formed the outer skin: the heaviest of this was situated around the bow, bridge, engines, and other critical areas, approaching about a metre in thickness at its greatest points. The remainder of the ship, though still armoured in the same manner, received significantly less: the maximum thickness was 300 mm, thinning to 225 mm in the least critical portions. To this outer layer was mated significant internal subdivision: plates which varied between 100 mm at their thinnest to 250 mm split the hull into hundreds of airtight compartments, sealed by heavy armoured bulkheads.

To the impressive armour was mated an equally-impressive shielding system: the standard *Prydwen* shield generator had seen upgrades since the days of the immediate post-Djangor era. The newest models combined directional gravity fields, electromagnetic shielding, and the standard sectored energy fields to create a barrier against any kind of incoming fire. Long experimentation with cooperation from the Veydreth ensured that the normal vulnerabilities of large starships - primarily to ion cannons - would be minimized under these new shields. Though not up to the standards of the powerful shields afforded to the latest Alliance flagships, they were considered far superior to the battlecruisers they were replacing.

### Other Details

#### Flag ("*Hestia*") Refit

The ***Hestia* refits** - named for the *Hestia* class which inspired the role - were a series of comprehensive upgrades undertaken to a few *Rhea*-class battlecruisers to bring them to 'flagship' status. Their ventral communications array was extended and replated-over, giving them a larger and distinctive 'fin' than in the normal models: their defensive systems were also upgraded, while their reaction cores were given costly improvements to handle the greater power drain. While part of the armament was reduced - some of the gunports were plated over - this was compensated for by the twin 380-megaton laser turrets being substituted for triple turrets of the same output.

#### *Diana* Refit

The ***Diana* refits** were a series of standardized upgrades to the *Rhea* class, undertaken as they came in for refit as part of the larger Diana Programme. These refits were generally undertaken to modernize their hangar arrangements to increase fighter capacity, improve power generation/consumption efficiency, and overhaul the engines: the relatively austere refits were due to the fact that these ships were still considered quite modern even in the 2540s.

## See Also

 *Tsukiyo*-class Star Battlecruiser | Himeko Consortium | One of the most powerful battlecruiser models, whether in the Milky Way and out. Though initially built only to free up more capable designs for fast attack groups, allowing the battlecruiser to take on the role of commerce protection, large numbers and the ability for non-Aetanii to crew them easily has allowed these ships to form their own offensive units. The ability to engage well outside the range of any other power makes these ships able to compete with full Star Dreadnoughts.