H90-Kastellax main battle tank

Development History
Development of the H90 Main Battle Tank (MBT) began in 1976. It was just a couple of years after the H80 entered service. Events in both the Sorland War and the Osorra-Tilenno War caused the Militarum to reconsider its previous tank designs and that the Imperial Army needed a well protected tank, which would also be superior or at least comparable to the models introduced by NSC and League of Free Nations states. To this end the Administratum Militarium conducted a study to weigh the cost options of upgrading existing vehicles vs a totally new design. At the conclusion of the study it was determined it would be more cost efficient to design a new vehicle as opposed to upgrading and modifying existing vehicles. A number of advanced technologies, for the time were incorporated into the H90 development project. Among these included an autoloader, additional independent commander telescopes, and a coaxial autocannon.

First prototypes of the H90 were completed in 1980, with the army ordering some 2000 vehicles in 1985. First production batch of 30 tanks was completed in 1988 and the H90, now called the Kastellax was adopted by the Imperial army during the same year.

Primary
The original production model H90 is fitted with a fully stabilized IARM-R60.52 120 mm smoothbore gun at 52 calibers long. Series II and Series III feature a ARM-R60.55 120 mm smoothbore gun at 55 calibers long. The H90s gun features a bore evacuator, with the optional addition of a compressed air unit to assist in evacuation of fumes. The gun's thermal sleeve is made of magnesium alloy, while the barrel features a chrome lining to extend barrel life and is capable of power elevating from +20° to −9°. The main gun of the H90 is stabilized on two axis, allowing the H90 to shoot on the move.

Autoloader
The H90 features an autoloader that holds 24 rounds in the ready mag in a carousel-type storage area in front of the hull plus 19 rounds in reserve and provides a sufficient rate of fire to deal with six targets located 1.5-2 km away, within one minute with a hit probability in 95%. The autoloader itself weighs 500 kg (empty) and has a total volume of 1.68 m3 (1.40 x 2.40 x 0.50 m). In case of ammunition cooking off, the deflagration is vented by two blow-out panels directing any explosions upwards away from the crew compartment.

The autoloader is managed by a T1000 Ultramar microprocessor, where the gunner selects the round that they want and the autoloading system digitally reads a bar code imprinted on each round to select and load the right round, if the ammunition does not have a barcode, its type is entered through a control keyboard. It is possible to replenish the autoloader under armor, through a port in the inner bulkhead by using the 18 rounds cylinder located to the right of the driver's position.

The R60 may be loaded manually as well, and can fire a wide variety of tank rounds. The primary anti-tank round of the Imperium is the Verutum Taxon-6.6 series of depleted uranium munitions. A tandem warhead round, the Verutum Taxon-6.6H, is also available, along with a, the Taxon-6.6C, and  Taxon-6.6HD. An electronically fused round, the Taxon-6.7, entered service in 2018, and is a programmable dual-purpose round with air burst capability that can be utilized in both direct and indirect fire capacities in addition to a number of ATGMS and other "smart" munitions.

Secondary Armaments
Secondary armament consists of coaxial 12.7 mm Helandros heavy machine gun and remotely controlled or up to two roof mounted 7.62x51mm Arsenios-53 machine guns. Series III variants are capable of having a 7.62×51mm  or remotely controlled autocannon.

NBC and Fire Protection
Series. II and Series. III H90s provide protection for the crew from nuclear, chemical, and biological attacks with the Chlamys NBC overpressurization system, which provides up to 4 millibars of over-pressure inside the vehicle in addition to environmental and atmospheric sensors alert the crew if the tank enters, or leaves a hazardous environment.

The H90 is also equipped with a fire protection system. Four 9 kg Halon fire extinguisher bottles are installed on the right behind the driver's station. The bottles are connected to pipes and hoses and are activated automatically by the fire detection system, when temperatures rise above 82 °C (180 °F) inside the fighting compartment, or manually via a control panel. An additional two extinguishers are located under the floor beneath the drivers seat, and under the floor of the commanders station.

Mobility and Propulsion
Due to the terrain, much of the Imperium is jungle, or rural tropic savanna with heavy rains, it was imperative that the H90 be lightweight, allowing the vehicle to cross bridges and roadways which would be inaccessible to heavier vehicles as a result the H90 has a combat weight of only 54 to 57 tons for the series III. Additionally due to the high probability of roadways and other avenues of travel being flooded the H90 is capable of fording 1.2 meters standard, and up to 4.2 meters with preparation. The H90 is also capable of traversing trenches 3 meters wide, a vertical step of 1.25 meters.

The H90 is powered by a TDE-450G-9 liquid-cooled V12 twin-turbo diesel engine delivering 1,500 hp allowing for an official maximum speed by road of 71 km/h and 55 km/h cross country. An additional TGT-659 gas turbine engine, acting both as a turbocharger and an APU giving auxiliary power to all systems when the main engine is shut down and works as an. The TDE-450G-9 provides the H90 with a 27 hp per ton power to weight ratio and makes the H90 capable of acceleration speeds of 0 to 32 km/h in 5 seconds. The H90 is capable of The H90 has a semi-active hydropneumatic suspension for improved cross country performance. The engine exhaust, exiting at the rear left, is cooled to reduce the thermal signature of the H90. The H90 has an automatic hydromechanical transmission with five forward and two reverse gears. Fuel tanks carry 1,300 litres and give the tank a range of 550km; two 210-litre external tanks can be fitted on the rear of the turret for an extended range of 650km.

Variants
'''Series. I'''

'''Series. II'''

'''Series. III'''

'''Series. III-X'''

H90-ARV H90-ARV includes both a  and a  with integral, allowing it to approach damaged vehicles, even over rough and fought-over terrain, and tow them to safety. It is equipped with up to two for local self-defense, a smoke, and NBC protection.

H90-AB The H90-AB developed from the H90 tank chassis. It is designed to carry a folding mobile bridge, which it can "launch" across a river. Once emplaced, the bridge is sturdy enough to support most vehicles, even other H90 and H71 tanks. When the crossing is complete, the bridge-layer simply hooks up to the bridge and re-stows it.

H90-MCV The H90-MCV is a based on the H90 chassis. It is equipped with a mine flail or bulldozer blade in addition to electronic mine clearing and marking suites

H90-CEV H90-CEV is a equipped with a, , and dual. The H90-CEV is based on the H90 chassis with a built up forward super structure and has a machine gun for defense, a smoke, and NBC protection

Users

 * Zahava