(Capital) OP-PA 'Gesturum' type Planetary Assault Ship
A mobile Orbital Platform developed by the Imperial Star ship Design Bureau (ISDB) in 4428 A.D and built at the Aquarian Imperial Naval Shipyards for the Imperial Planetary Forces and specialist divisions of the Imperial Marine Corps. Gesturum-type vessels serve as the primary direct landing ships for planetary assault in the Imperial Military, being able to transport, deploy and support up to 20,000 IPF soldiers and more than 1000 armoured vehicles including heavy MBTs for extended planetary surface campaigns.
Class: Orbital Platform (Capital)
Role: Orbital Assault / Planetary Landing
Crew: Up to 1200 personnel, up to 20,000 fully equipped IPF Soldiers, up to 5000 IMC Marines, up to 1000 Crimson Heavy-Marines (Exosuit)
Mass: 1,350,000-1,400,000 T
Max Speed (Impulse Cruise): <970 M/s
Max Speed (Hyper Cruise): < 250 KM/s
Max Range (JDA): >20 Parsec
Date: 4428 A.D
Origin: Aquarius Imperial Naval Shipyards, Lorentis System
Primary Armour Plating: Nanopolymer-based low-metallic, mass-reduced composite construction, with NPLM self-healing ablative layer and NPLM hardened mesh core
Primary Armour Thickness: =< 25M (Main, Frontal Arc), =< 4.25 M (Secondary, Side, Dorsal Arc), 15.75M (Secondary, Ventral Arc), =< 0.65M (Tertiary & Pressure, Rear Arc)
Spinal/Axial Armament: N/A
Primary Armament: [DATA LOCKED]
Secondary Armament: [DATA LOCKED]
Tertiary Armament: [DATA LOCKED]
Missile/Torpedoes: [DATA LOCKED]
Shielding: [DATA LOCKED]
Sensors: [DATA LOCKED]
Propulsion: [DATA LOCKED]
Powerplant: [DATA LOCKED]
Orbital Platform Planetary Assault (OP-PA), of the Gesturum Type (Old Earth Latin "Carry On", "Break Through") is a mobile orbital platform of the capital designation designed by the Imperial Starship Design Bureau (ISDB), with development starting on a new project for a heavy amphibious landing starship capability as early as 4405 A.D, shortly after the Unification protocol the cycle prior. The Old Federation, and subsequently New Federal Navies operated by the UAS that were largely inherited by the new Imperial Navy, lacked a dedicated planetary assault landing capability of the scale required by the IMperial Navy Doctrine of direct planetary invasion (and counter invasion) going forward into the 45th and 46th centuries.
The existing capability relied on larger standalone warships such as the Evolution-class (EV) Super Carriers (themselves inherited from the UAS EV-AX class) to transport troops and assault assets internally without the need for a dedicated platform. While appropriate for most operations, the Imperial Navy Admiralty highlighted a concern that during such an operation, the Fleet's EV-class Carriers would have to be split between committing to planetary assault, and those supporting the fleet's space-combat capability. Since the Navy did not have plans to press more than half a dozen EV-class Carriers into service (in favour of the heavier RTII-class Dreadnoughts), the Admiralty requested a dedicated landing ship be drafted; especially in the event that a major world in the Imperial States would be attacked and require a strategic-scale ground forces deployment to defend it (atop the planet's own garrison).
Officially Designated as a Mobile Orbital Platform, but covered under the "Capital" designation when operating in the Imperial Navy Fleet, the Gesturum-type is designed to break through hostile orbital defences and insert troops via smaller dedicated landing craft from low orbit, using powerful magneto and gravimetric stabilisers to keep the vessel stable. Due to the need for enormous internal hangars for stores, troops, equipment and vehicles, the Gesturum is physically larger than many heavy warships in the Imperial Fleet, such as the ED-class battlecruiser; with the latter being just under 1.5 KM, Gesturum measures in at just under 1.7KM, making the the second largest mobile vessel currently in service with the AIN, after the EV/RT-class sister hulls.
The focus on the ability to breakthrough active orbital defences (such as in a situation where the Imperial Navy hasn't been able to achieve full orbital superiority) resulted in a design with an emphasis on directed, frontal defences. The most iconic aspect of this being the protruding "head" of the vessel; this section is suspended on powerful magnetic shock absorbers that allow the incredibly thick frontal armour to withstand direct impacts from powerful planetary-based anti-orbital cannons. The armour on the frontal arc of the "head" is thicker than any other warship in the fleet, with 25M of Low Metallic Nanopolymer Composite plating including self-healing ablatives, thicker than even the massive RT-II Class Dreadnought's 15M primary belt.
In addition to the heavy armour, the Gesturum-type platform possesses the most powerful directed CTM Shielding Array ever deployed on a mobile vessel, focused entirely around the frontal arc to further protect the ship's approach to a low-atmospheric position, even under the heavy fire from hostile capital-class warships. The Ventral portion (lower) of the ship is also heavily armoured to resist direct attacks from hostile anti-orbital fire if the vessel is in a horizontal alignment with the surface.
The primary armament consists of a pair of B-type hardpoints, typically used for self-defence against smaller enemy ships such as destroyers or frigates, the standard configuration for Gesturum-type vessels is pair of HAL2 Directed Laser Cannons. In addition, the platform also supports four more specialist B-type hardpoints for dedicated anti-surface weaponry; allowing the Gesturum-type to support deployed ground forces with precision orbital bombardment. A pair of Hornet-GL type (Ground Attack) batteries also provides Orbit-to-Surface ballistic missile capability.
Due to is considerable weight, the Gesturum-type is extremely slow and unable to alter course in Cruise Speed; as such, it must be escorted into an approach vector by friendly warships. The Imperial Navy's newer Thunderhead (TH)-class Heavy Cruiser possesses a similar frontal-arc protection emphasis and would likely be committed to providing direct support for Gesturum-type vessels in a hostile planetary assault scenario.
The Imperial States currently fields a dozen OP-PA Gesturum type vessels, all of which are currently assigned to the Imperial Navy Sector Defence (INSD) contingent in Lorentis. Their primary role in 'peacetime' is to provide counter-insurgency planetary assault and strategic reinforcement for Imperial Worlds that request additional Imperial Planetary Forces support. As such, they operate outside the regular chain of command in the AIN, answering to the Lorentian INSD HQ. However, in times of war, the platforms can be assigned to various Imperial Navy Fleets as per requirements, in the event that a planetary body must be occupied outside of Aquarius, the Angel, Tempest and Crimson-sector Expeditionary Fleets would each receive a pair of Gesturum-type vessels with full regimental strength IPF troops.
Low Orbital insertion of troops is performed by docked Heron-class Orbital Dropships; these frigate-sized vessels are carried externally under the Ventral section of the Gesturum, with direct wet-dock connections with the internal hangars for full loading/unloading capability of troops, vehicles and supplies as needed. The Heron-class dropship lacks an independent Jump Drive Array, and as such, operates dependent on the OP-PA platform.
(Top) OP-PA Gesturum-type Planetary Assault Ship with a pair of externally docked Heron-class Orbital Dropships.
(Below) OP-PA Gesturum-type PAS, rear view, without docked dropships.