Type 98 Chi-Ho

Type 98 Chi-Ho
Place of origin  Empire of Japan
Production history
Designed 1939
Produced 1939
Specifications
Crew 4
Armor 5–25 mm
Main
armament
 Experimental Type 97 47 mm cannon
Secondary
armament
 two 7.7 mm Type 1 heavy machine guns
Engine Mitsubishi A6120VDe air-cooled inline 6-cylinder diesel 14,300cc
120 hp (89.5 kW)/ 1400 rpm
135 hp (100 kW)/ 2000 rpm
Suspension Bell crank

The experimental type 98 medium tank was developed on order from the Imperial Japanese Army chief staff. It was completed in July 1939 (Showa 14). "Chi Ho" indicates that it is designated as the 5th (I, Ro, Ha, Ni, Ho) medium (Chi) tank.

It was well known that the IJ army chief staff was in search for a successor to the type 89 medium tank. The experimental Chi Ni medium tank was considered as meeting the requirement of a "light and low-cost tank which can be deployed in large numbers"; while the Chi Ha (later the type 97 medium tank) was thought of as the more effective fighting vehicle. With the outbreak of the Sino-Japanese war, the army`s budget drastically increased which resulted in the contest over which was to become the successor, with the Chi Ha being selected.

However the army chief staff did not give up on the idea of a low-cost light tank and thus a vehicle was developed. By being completed in Showa year 14 (Imperial year 2699) the naming convention at the time would suggest the tank being named the type 99 but the unofficial type 98 name probably stuck after regular use by those involved in the tanks planning.

External characteristics

Heavy emphasis was placed on a gun with a high penetration and the long and high velocity 47mm tank cannon was selected. Both the Chi Ni and the Chi Ha were to be used as infantry support tanks which were armed with the low penetration 57mm tank gun.

The following changeover looked very sharply at the next medium tank shortly before this vehicle was completed. In the changeover sent to the tank research committee in March Showa 14 were design conditions "For the next tank`s turret, even if taking the 57mm cannon into account, further research will be made into firepower. The caliber, if by no choice, will be no smaller than 47mm. The likelihood of being pressed into tank battles in future wars is something that should be considered." Most notable is that the last sentences describes what did happen later in the same year, in June, with the Nomohan incident and later, again in the same, in September, with what was happening in the invasion of Poland.

This tank`s experimental 47mm tank cannon was derived from the research results of the "Experimental type 97 47mm cannon" and the "experimental 47mm cannon". From June 1940, a completed cannon of the experimental 47mm cannon begun various testing and in September of the same year, the experimental 47mm tank cannon was mounted on the vehicle`s turret. The turret was then mounted on a type 97 Chi Ha`s hull and underwent penetration resistance testing.

The intention behind the machine gun being mounted in the forward left side of the turret is not clear but supposedly, it may be akin to a coaxial machine gun. A coaxial machine gun is placed alongside the main armament on the same axle. With that setup, when using the main cannon, the machine can do things like help predict were the main cannon`s fire will land or suppress the enemy while loading the main armament. Out of all of the tanks in the army, only tanks like the type 98 light tank or type 2 light tank mounted a coaxial machine gun. Incidentally, at the battle fronts of the pacific war, it is said that Japanese tanks were easily destroyed by bazookas because it was not possible to aim at the enemy while loading. This gave the enemy time to aim carefully.

The machine gun mounted in the turret was not a belt-fed type but rather the type 97 tank-mounted heavy machine gun that used 20-round magazine clips. This presented a limitation in sustaining continuous firing attacks. There was no alternative available to address the issue.

The engine mounted in the experimental tank was a 6-cylinder diesel that perhaps came from either the type 89 medium tank or the type 95 light tank. But in any case, it was proposed that the tank was to receive the Mitsubishi 160 HP 8-cylinder diesel engine. Also it was the first Japanese made tank to use a hydraulic system in the steering system. It is said that the result should have been satisfactory.

Up until then, some advances over the Chi Ha variants can be seen, but some aspects in the tank hull were still lagging behind. A slid was attached to the rear part of the hull. This is something commonly seen in World War I and inter-war tanks. It is often said that by extending the length of the hull, it gained the benefit of crossing trenches but in that, there was a problem. In one theory, because the FT-17 became the origin of current medium tanks of the day and mounted a slid, among many countries, including Japan, "Slid on tank" was common sense. But as a tank mounts a slid, it becomes tail heavy (center of weight shifts backwards) and that presented uncertainty when crossing wide trenches. Mounting a slid on a tank that normally does not have a slid would likely have been ineffective. By becoming tail heavy, the rear portion of the suspension would undertake a greater load and thus wear out faster. Furthermore, the somewhat increase in weight would reduce things like mobility. In the case for the Type 89 medium tank, in reality, it seems like the only advantage lost by mounting a slid was that it could not mount additional loading cargo spaces.

With the applied limitations on the tank`s weight, it is not believed that the armor protection level could have been improved. Without a copula, it is undeniable that the ability to observe outside would have been worse than the Chi Ha variants.

In the end, whether or not it was due to the direction described, this tank was not selected for production. Perhaps the greater reason was because the 2 year ago selected Chi Ha was already advancing in production and there was probably no desire to interrupt that production by adding a new tank for production.