Iapetus-class battleship

## *Iapetus* class

The ***Iapetus*-class fast battleships** were the design successors to the *Mars* class and the natural evolution of Alliance warship construction. The most modern and powerful capital ships of their type in the Terran Alliance, they were only available in limited numbers due to cost: a single *Iapetus* could cost the same as five *Mars*-class battleships.

 Design

 At 1.65 km in length, the *Iapetus*-class star battleships were the longest and largest of the new-generation battleships being produced for the Alliance Navy: outsizing both their *Mars*- and *Neptune*-class progenitors to a significant degree, this enhanced size was useful for the addition of their all-new power generation equipment and potent weapons systems. Also used as command ships, thanks to their superior tactical displays and comms systems, these ships had one goal in mind: aggressive fleet combat. Their long single-hull shape was in marked contrast to accepted practice, and the smoothed flares and canards in their basic box-like hull made them more similar to a Consortium starship than it did an Alliance one: however, their basic form was derived from a Velian model.

While initially conceptualized in the aftermath of the Razorbird Crusade against the Alliance, the *Iapetus* prototype received major design funding and updates to their proposed hullplan only after the destruction caused by the extragalactic Rin Empire during their last invasion of the Milky Way. Bringing multi-kilometre capital ships to every battle, the Rin had proven themselves capable of overwhelming most Council capital ships with ease: multiple *Terra*-class Star Dreadnoughts were typically required to counter a single battleship. In lieu of meeting size with size, the Alliance instead chose to continue to pursue a policy of redoubtable, compact weapons platforms. Influenced by Consortium, Lucaelian, and even Vespiran starship designs, the result was a high-speed warship of unparalleled combat potential in the Alliance fleet.

One major difference from even contemporary Alliance warship design was the placement of the main observation bridge on the *underside* of the vessel. The primary combat bridge was, as in all Alliance warships, buried in the heart of the warship.

### Power & Propulsion

The *Iapetus*-class battleships had a significantly more powerful energy-generation plant than any other warship in the Terran arsenal: a locally-designed and produced version of an ionization reactor, the Terran **reaction core** was a substitution for up to thirty-six separate cold fusion or eight matter/antimatter reaction chambers. One cost of this high-output power plant was a significant increase in required antimatter fuel, thus lowering their operational endurance without the aid of numerous resupply ships, but the power generation capabilities were such that an *Iapetus* could operate all of its systems at maximal capacity at once without putting strain on its core.

For their propulsion, the *Iapetus* model was well-equipped with two primary ion-impulse nacelles and three secondary drives: four tertiary and two quaternary thrusters completed the total forward acceleration package, resulting in impressively high manoeuvrability for an Alliance warship of this type. Just one engine unit produced as much thrust as the entire engine section of a *Mars*-class battleship: however, the huge amounts of expelled propellant - one ship could burn through more fuel in a single engagement than ten *Mars* battleships - ensured these ships required frequent resupply. Orientation and secondary manoeuvring characteristics were provided by dozens of individual Vernier thrusters and ion-drive vents: protected by armoured panels when not in use, they allowed an *Iapetus* to perform pinpoint-accurate turns and orientation changes with minimal propellant loss.

### Weapons

The defining factor in a battleship is the firepower it can bring to bear on a target: the *Iapetus* type was no exception in this regard. Much like its *Luna*-class battlecruiser counterpart, the *Iapetus*'s primary weapon was a massive 450-gigaton spinal-mounted burnthrough laser: a superweapon capable of annihilating almost any target in one hit, it was even more powerful than the *Luna*'s own superlaser and second only to the more powerful variants carried by the experimental battleships *Minerva* and *Euryale*, and the Alliance's newest *Atlas*-class Star Dreadnoughts. Thanks to the power generation capabilities of the battleship, an *Iapetus* could continue to go 'weapons free' with all of its guns while the superlaser was in operation, something the *Luna* was incapable of.

The heavy artillery of an *Iapetus* consisted of about twelve triple turrets for 380-megaton super-heavy laser cannons: just one shot expended more energy than the entire gun battery of a *Mercury*-class battlecruiser, or multiple turrets aboard the *Neptune* class; only the main batteries of the latest *Jupiter*-class Star Dreadnoughts and *Miranda*-class battlecruisers were on par. Miniaturized collimation chambers, as a result of investigation into Alinar techniques, allowed them to decrease the size of the turrets from their normal bulk with only a slight loss of power: this allowed them to be retractable into the hull, concealing their full firepower until necessary. Excellent forward firing arcs meant every cannon could be brought to bear ahead, with over half capable of firing to the broadside. Each turret was given its own capacitor and three backup battery cells (one for each gun) in case of action damage to the power conduits from the ship's reactors: the latter could also be decoupled in case of overload danger or if the guns were out of action, so as to prevent power drainage.

The 'medium' anti-ship armament was considerably 'beefed up' compared to its contemporaries in the Alliance: while most Alliance battleships were armed with a split secondary battery—15-megaton laser cannons for anti-ship work, and 10.5-kiloton batteries for dual-purpose work against light craft and starfighters—the *Iapetus* stripped away the 'handy' 15-megaton in favour of the much more powerful 20-megaton laser cannon: these were the exact same guns used aboard a modern *Deimos*-class heavy cruiser, in over twenty-eight (28) triple mounts scattered across the surface of the vessel to provide complete coverage.

To the impressive main guns were added a formidable 10.5-kiloton 'medium' battery of long-range laser cannons, emplaced in twin rapid-firing turrets and studded through the hull. These were the standard dual-purpose guns of Alliance warships, being useful against both smaller vessels such as destroyers and as point defense against starfighters and ordnance like torpedoes. They had an extraordinarily high rate of fire and were completely subdivided from the hull once 'closed up' for action, meaning that even if one was destroyed the ship would not suffer depressurization. The redundancy was a feature of all Terran designs, and extended to the main and secondary armament as well.

Medium-range point defense was handled by a reliable battery of fifty (50) twin 6.5-ton laser batteries: upscaled 2-t snappers, they could confidently engage targets outside the 'kill zone' of the 2-t lasers, but within the optimum range of the 10.5-kt cannons: these weapons proved highly successful from their introduction, first seeing service on the *Pandora*-class maintenance carriers.

For close-in defenses, the *Iapetus* battleships were equipped with over two hundred 2-t laser cannons in twin 'snapper ball' mounts - so-named because they could snap a crewman out of their seat from the G-forces if their harness was not secured. The guns could be controlled remotely in their default setting or operated on-site by a single gunner. With a sustained 'burst' mode of 10,000 shots every minute, they were capable of burning clean through an entire swarm of torpedoes launched at close range and were one of the most well-regarded point defense systems in the entire galaxy.

Additional armament was backed by large numbers of 5-mt laser blasters, swarm torpedoes, and missiles; the former were for close-range broadside combat, where their relatively slow firing rate for calibre (only about 3,000 shots every minute) was made up for with hitting power: they could burn cleanly through a metre of starship hull armour if given a continuous track on the same spot for less than seven seconds. However, these weapons were not particularly effective against shields.

As a consequence of this comprehensive battery of weapons, the *Iapetus* class was considered particularly cramped: crew were known to have to 'hot bunk' on campaign, and sometimes had to be housed on their accompanying supply train if battle was not imminent.

### Defensive Systems

As a battleship—and *especially* as a battleship designed and constructed by the Terran Alliance—the *Iapetus* class was heavily shielded and armoured: its outer layer of defense was the Alliance-unique ***Prydwen*** sectored shield system, which could oscillate its frequencies, strengthen a specific area of the shields, or keep sections of the shields intact while idling others to conserve power.

To this formidable shielding system was added significant quantities of armour: 750-mm plates separated the outer skin of the hull from the pressure seal, which itself was backed by a second layer of 375-mm armour plates to stop leakages and provide a second barrier that a projectile or energy weapon would have to bull or burn through. The hull itself was also finely subdivided into thousands of airtight compartments, with numerous redundant sections and their own independent life support systems: each section housed one of the ship's reactors, allowing them to sustain not only themselves but also adjoining sections that might suffer damage as well as continuing to operate subsystems. The armoured bulkheads which separated each compartment were double-layered: not only were they thicknesses ranging from 375-mm to 750-mm thick, they could also be charged plates (around the reactors) and/or could be reinforced by the sectored shielding system.

The most armour, however, was reserved for the critical subsystems: each reactor compartment, the bridge, the main power conduits, and the primary and secondary gun turrets were protected with anywhere from one to three metres of armour plating. The barbettes for each turret which extended into the ship before narrowing down to a simple tube to protect the conduits were also a full metre thick, and backed with a second layer 500-mm thick to provide an extra barrier for an enemy round or beam to get through.

## See Also

 *Nova*-class Star Battlecruiser | Murrcioun Syndicates | The Murrcioun battlefleet's latest battlecruiser, armed with wave-pulse positronic 'shock cannons' and heavy mass drivers to devastate targets both ahead and on the broadside. Poor ahead and astern fire is a problem for the broadside-oriented Murrcioun but the *Nova* type's comprehensive secondary armament of energy projectors rectifies some of that weakness, at least at close range.