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.
