A Type 89 Otsu performing in its role of infantry support
The Type 89 “I-Go” or “Chi-Ro” Tank was the mainstay “medium” tank of the Japanese military for roughly a decade from 1931 onward. It was used extensively in Imperial Japan’s territorial expansion throughout Asia. It has generally been overlooked in games and media because of its reduced role in World War 2, by which time it was considered obsolete and had long since been replaced by the Type 97 Chi-Ha. It remains a historically important vehicle, however, due to the role it played in infantry support throughout Japan’s campaigns in China and Manchuria and early expansion in the Pacific. Any game that intends to illustrate Japan’s offensive role of conquest prior to WW2 should include the Type 89.
Designed in 1928, it had a maximum armor thickness of 17mm, which while fine for an “interwar” tank, and comparable to a Soviet BT-7 light tank designed 6 years later in 1935, was light by WW2 standards. The American M2A4 Light Tank, which saw battle in Guadalcanal by the US Marines, by comparison was designed in 1935 and had an armor thickness of 6–25 mm. The armor of the Type 89 was more than sufficient to protect it from rifles, older machine guns, and small arms available to the Chinese and other opponents at the time, and it was also an instrumental tank in the charge of the 4th Tank Regiment under General Yasuoka that broke Soviet lines (despite far superior numbers on the Soviet side) in the Battle of Khalkin Gol.
Tanks like the Type 89 were useful as a shield for advancing infantry and for destroying enemy fortifications. Once a Type 89 had pulverized an enemy pillbox or building, the Japanese troops could proceed without fear of snipers, machine guns, or even lightly armored vehicles which the Type 89 could also dispatch.
There is ample information on the Type 89 Tank and photos and data are not difficult to come by. An entirely Japanese design, it has a striking upright profile and is immediately recognizable. Multiple variants existed throughout its long career, but the two major models were the Kou and the Otsu. The gun from the Type 89 Otsu was later re-used on the Type 97 Chi-Ha. The gun was a Type 90 57 mm Tank Gun with a barrel length of 0.85 metres (33 in) (L14.9) el angle of fire of −15 to +20 degrees, AZ angle of fire of 20 degrees, muzzle velocity of 380 m/s (1,200 ft/s), and could penetrate 20 mm of armor at 500 m (0.8 in/550 yd).
With a powerful gun for its time and decent armor for the period, if the Type 89 had a weakness it was that it was slow with a top speed of only 15.5 km/h. This slow travel speed is one reason the Japanese army invested in armored trains and rail-capable armored cars in China. One can only imagine the painfully slow progress of the I-Go across the vast Chinese countryside.
Type 89 A I-Go Kō (八九式中戦車（甲型）)
The initial production model had a water-cooled Daimler-type 100 hp engine (ダ式 一〇〇馬力 発動機 da-shiki hyaku-bariki hatsudōki?) 6-cylinder gasoline engine and mounted a machine gun on the right side of the hull. This design could only attain 15.5 km/h, and was also limited by the severe winter climate in northern China. A total of 220 units were produced.
Type 89 B I-Go Otsu (八九式中戦車（乙型）)
The Ko was superseded in production from 1934 by the model Otsu with an air-cooled Mitsubishi A6120VD 120 hp diesel engine. The improved model had a new gun turret design complete with a cupola for the commander, and with the machine gun relocated to the left side of the hull. The multiple armor plates of the front hull were replaced by a single shallow-sloped frontal armor plate which provided more protection for the driver. However, the major difference between the versions was the Mitsubishi air-cooled 6-cylinder diesel engine, which had several advantages: reduced vulnerability to fire should the vehicle be hit or roll over; better fuel economy; greater torque at lower revolutions. A diesel engine was also preferred by the Japanese Army because more diesel fuel than gasoline could be produced per barrel of oil. A total of 189 Otsu units were produced. The Type 89B Otsu version was the first mass-produced tank with a diesel engine.
Trivia: The Type89 Otsu was featured in the animation Girls und Panzer, and a very good 1/35 scale model kit by FineMolds was issued under the Girls und Panzer brand as a result of the popularity of that show. The model kit decals can easily be adjusted to make the Type89 into a historically correct vehicle.
Type89 Ko model kits are much harder to find currently.
Video Link of the Type 89 I-Go in action: http://www.youtube.com/watch?v=vYj4Ll4RWnk
Note the machine gun on the left side of this earlier Kou model Type 89 – Caption reads roughly, the “Heroic Shape Tank”