Cyllene-class battleship

## *Cyllenne* class

The ***Cyllene*-class battleships**, often referred to as ***Cyllene*-class "small battleships"** or as ***Alexhelios*-class pocket battleships**, are a series of 'colonial service' warships in the Terran Alliance Navy. Heavily armed and highly maneuverable, they are designed for service on the frontiers to free up larger and more durable *Mars*- and *Neptune*-class battleships for the core fleets.

Many of these ships would eventually be produced for 'fleet work' as well: their overall excellent qualities made them a foundation for the later *Hestia*-class 'colonial' flagships.

## Design

### Design History

Meant as a cheaper, more maneuverable alternative to the continued production of the fast-approaching-obsolescence *Mars* class and freeing up those warships for refit and upgrade for service in the core fleets, the *Cyllene* class stemmed from requirements not unlike their *Rhea*-class counterparts: an enlarged *Deimos*, suitable for long-term missions. However, the same uptick in mass and size due to the deteriorating international situation that afflicted their battlecruiser sisters also struck the *Cyllene* type: their slower acceleration from the outset allowed for more substantial upgrades.

By the time design work was completed, the *Cyllene*s resembled downscaled *Iapetus*-class battleships in most ways: their basic design, however, actually stemmed from the experimental flagship *Achilles*. As with the *Rhea* class, new engine arrangements were adopted to improve their radius of action and reduce propellant consumption; this provided the ability to upgrade the armament past the *Rhea*'s levels.

### Dimensions & Role

At exactly one kilometre in length, the *Cyllene* battleships were no longer than the old *Mercury*-class battlecruisers and substantially shorter than the *Mars*-class battleships they were intended to replace on the frontier: substantial mass savings, however, allowed them better maneuverability than either. 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. Unlike the *Rhea* class, the *Cyllene*s did not operate ramjets forward of the engine pods: accordingly, they could not operate in an atmosphere.

As with other Alliance battleships, the *Cyllene* class served both traditional 'fleet' work as a gunline combatant and as a flagship to smaller groups on the tactical level.

### Power & Propulsion

As with most other modern Alliance starships, the *Cyllene* 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, though not to the same extent as the *Rhea*s- 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 *Mars* 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 *Cyllene*-class battleships, as a result of carrying no fighters, could be considerably better-armed than their *Rhea*-class counterparts: they had more firepower than the *Mars* class they were intended to supplant. Their primary weapon was a 430-gigaton spinally-mounted superlaser: its dish was located immediately beneath the raked prow. The heavy artillery for the class, supplementing this weapon in normal combat, took the form of twenty-one 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 three triple turrets and twelve fixed-forward gunports on the angular bow. Advances in beam collimation chamber miniaturization allowed for the size of the turrets to be significantly reduced, allowing the *Cyllenne*s to carry two dorsally and one ventrally on the centreline. The turret-mounted laser cannons, could, additionally, be cut-in using specialized loadable cartridges to function as ion beam cannons.

Secondary armament was comprehensive: the 'dual-purpose' gun was finding credence in the Alliance at this time, allowing the *Cyllenne* battleships to field over three 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 *Cyllene* could unleash a truly massive salvo to devastate any opponent within range.

### Protective Systems

As with all Terran battleships, the *Rhea* class was considerably better-protected than the galactic standard: though thinner-skinned than most modern Alliance battleships, to the point where they would be criticized for 'poor armour', they were actually extremely resilient in the face of 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 two metres 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 380 mm, thinning to 290 mm in the least critical portions. To this outer layer was mated significant internal subdivision: plates which varied between 150 mm at their thinnest to 300 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.

## 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.