Type 74


The Type 74 is a main battle tank of the Japan Ground Self-Defense Force. It was built by Mitsubishi Heavy Industries as a supplement to the earlier Type 61. It was based on the best features of a number of contemporary designs, placing it in the same class as the US M60 or German Leopard 1. Like these designs, it mounts the Royal Ordnance L7 rifled 105 mm gun. The design did not enter widespread use until 1980, by which point other Western forces had introduced more capable designs. It was followed by the heavier Type 90. Both the Type 74 and Type 90 are supplemented and will be eventually replaced by the new-generation Type 10 tank.

History

The JGSDF began studies on new tank designs with Mitsubishi in 1962, after the Type 61 had been shown to be outmatched by new Soviet tanks such as the T-62. Features from several designs were incorporated, including the controllable suspension of the US-German MBT-70 project, the hull of the Leopard 1, and a similar 105mm gun. The design included a rotating cupola for the commander, and a new autoloader for the main gun. Prior to the 1965 decision to design an entirely new tank, some technologies which would later be used in the STB-1 were already in development independently in Japan. The design was finalized in 1964 and various test rigs were built between 1964 and 1967.

Design

Armament

During the development stage, engineers opted for a license on the NATO standard Royal Ordnance L7 105mm cannon. Japan only produced the barrel under license, developing an indigenous mantlet, breech and recoil system. The full length of the cannon was 5,592 mm, for a total weight of 2,800 kg. Initially, the main gun only used APDS and HEP as its primary ammunition. Later it was modified to fire APFSDS and HEAT-MP shells as well.
The secondary armament consisted of a 12.7mm anti-aircraft machine gun and a 7.62 co-axial machine gun.

Mobility

The Type 74 tank is powered by the Mitsubishi 10ZF Model 21 10-cylinder two-stroke cycle diesel engine providing 750 hp. At 19 hp/tonne, its power-to-weight ratio is similar to the French AMX-30. The maximum quoted road speed of the Type 74 is 53 km/h; however, speeds of at least 60 km/h have been achieved.

Armor

Instead of composite armour, the Type 74 adopted welded steel plates for hull construction, with sloped armour extensively used to defeat armour-piercing shells and other kinetic energy penetrators. It has frontal hull armor of 80 mm with an effective armor thickness of up to 189 mm for the upper glacis and 139 mm for lower glacis. Side armor is 35 mm, while rear armor is 25 mm thick. The cast steel turret has an estimated 195 mm of armor. When compared to other second-generation MBTs, the Type 74 has more armour than a Leopard 1, but less than comparable Soviet vehicles such as the T62.

Service

The first prototype, designated STB-1, was delivered in late 1968 and underwent a number of modifications until 1969. The autoloader proved too complex and expensive, and was removed, as was the remote-controlled anti-aircraft machine gun. The overall design of the turret was also changed, becoming longer. These changes resulted in the STB-3, which was delivered in 1971. The final prototype, designated STB-6, was delivered in 1973. Production finally started as the Type 74 in September 1975, with 225 being delivered by January 1980. Production ended in 1989, with total production running to 893 examples.
In service, the tanks were updated with the addition of infra-red imagers rather than image intensifiers for the commander and gunner, and a laser rangefinder in the commander's cupola. The gunner's position included a digital fire control computer, fed range data from the commander's range finder. Rounds for the main gun were upgraded from HEP to APFSDS and HEAT-MP.
The Type 74 was considered outdated even before it entered service. The Type 90 was to have replaced it outright, but with the end of the Cold War, these plans were scaled back. In 1993 four Type 74s were improved to the new Type 74 Kai standard, adding a passive infrared camera and side skirts. The upgrade proved to be extremely expensive, and the program was abandoned.

Variants