Research and development into a new Japanese MBT began in 1976, under the Designation STC, subsequently being renamed the TK-X by the Technical Research Headquarters of the Japanese Self-Defence Force. Funding for the engine, gun, ammunition and fire control system began in the Fiscal Year 1977 and for the suspension and the new armour in Fiscal Year 1978. The prime contractor for the Type 90 is Mitsubishi Heavy Industries, who have been the prime contractor for all Japanese post-Second World War tanks including the Type 74 and the Type 61. The Type 90 and all its subsystems have been designed and built in Japan, with the exception of the 120mm smoothbore gun, which is made under licence from Rheinmetall of Germany. It is the first Japanese tank to be at the cutting edge of technology, and in several aspects, it is ahead of most its competitors. Major sub-contractors include the Japan Steel Works, Mitsubishi Electric Corporation. Fujitsu and the NEC Corporation. The final requirements for the Type 90 were completed in 1980, with two prototype vehicles, both armed with the Japanese 120mm gun, firing Japanese ammunition, being produced by 1984. These were used in extensive troop trials that continued throughout the following two years. A second group of four prototypes were built between 1986 and 1988 that incorporated a number of changes as a result of the trials. They were armed with the Rheinmetall 120mm smoothbore gun, which is also fitted to the Leopard 2 and M1A1/M1A2 Abrams tanks. These vehicles were then used for development and user trials, which had been completed by 1989. The TK-X was type classified and redesignated the Type 90. Production started in 1992 and by 1999 is estimated that some 150 vehicles have been built, while production is still underway. The Type 90 and its variants, have not been offered on the export market.
Details of the armour used in the construction of the Type 90s hull and turret have not been released, but is understood that there is an extensive use of composite armour, particularly over the frontal area of the tank. The Mitsubishi Steel Works and Kyoto Ceramic Company have been responsible for much of the development of this armour. The layout of the Type 90 is conventional, with the driver seated at the front left of the hull and is provided with a single piece hatch and three day periscopes, the centre one of which can be replaced by a passive periscope. The turret is similar to that of the Leopard 2 with vertical front, sides and rear, and a bustle that extends well over the top of the engine compartment. The commander is seated on the right of the turret with the gunner and on the left and an automatic loader been mounted in the turret bustle, for which was designed by Mitsubishi Heavy Industries. It is believed that it can hold a total of 16 rounds of ammunition for the main gun, with additional ammunition located next to the driver. A number of blow-out panels are provided in the turret roof. The commander is provided with a vision blocs for all-round observation. The main armament comprises a 120mm Rheinmetall smoothbore gun, made under licence from Germany. The ordnance and breach are identical to the German 120mm smoothbore gun, but the recoil system and gun mount were designed and built locally in Japan. A 7.62mm machine gun is mounted coaxially to the left of the main armament, while eight 12.7mm (0.5) machine gun is mounted on the roof. There are also two banks of three electrically operated smoke grenade dischargers, one on either side of the turret. The gunner has a periscope sight that is stabilised in azimuth, while commander has a periscopic sight capable of 180 degrees traverse with dual axis stabilisation, both linked to a digital fire-control computer. The gunner has a day channel, a thermal infra-red sensor and a laser rangefinder. The gunner's sight is manufactured by the Nikon Corporation, the commander's sight by the Fuji Photo Optical Company and the thermal unit by the Fujitsu Company. The fire control system includes an advanced auto-tracking capability that is based on the output of the thermal imager and is effective against ground targets and can use while the tank it is both stationary and in motion. The commander's dual axis stabilised sight, permits him to require and engage targets directly, but additionally, the commander can hand-off a target he has acquired to the gunner, by pushing a button on his override control handle. This provides the tank with a hunter-killer capability. Mounted towards the front of the turret roof is a laser detector, which provides an audible signal, as well as an indication of direction at the commander's station. The suspension of the Type 90 is really a hybrid type, with torsion bars for the centre two road wheels and hydro-pneumatic units for the first and last two road wheels. There are six dual rubber-tyred road wheels, drive sprocket at the rear and an idler at the front. The upper part of the track is protected by a light-weight skirt. The engine is a Mitsubishi 10ZG 10-cylinder diesel (1,500hp) coupled to an automatic transmission incorporating a torque converter with an automatic car lock-up clutch. An NBC system is fitted as standard. Variants include the Type 90 mine-clearing MBT (which has a Type 92 mine clearing roller system fitted), the Type 90 Armoured Recovery Vehicle and the Type 91 Armoured Vehicle-Launched Bridge.
Hull length: 7.5m. Hull width: 3.05m. Height: 2.34m. Crew: 3. Ground Clearance: 0.45m (adjustable between 0.2 to 0.6m front and back) Weight: 50,000kg (combat) Ground pressure: 0.89kg/sq.cm Max speed: 70km/h. Max range (internal fuel): 400km on road. Armament: 120mm smoothbore gun, 1 x 7.62mm machine gun mounted coaxially, 1 x 12.7mm (0.5) machine gun on turret roof.
Bibliography
Foss, Christopher. Jane's Main Battle Tanks, 2nd Edition, Jane's Publishing Company, London, 1986. Foss, Christopher. Jane's Tank Recognition Guide, HarperCollins Publishers, Glasgow, 1996. Gelbart, Marsh. Tanks: Main Battle and Light Tanks, Brassey's (UK) Ltd, London, 1996.
