Lone Sentry: Modernized Tanks, with Heavier Armor, May be Expected (WWII Tactical and Technical Trends, No. 51, October 1944)

More effective Japanese armored fighting vehicles, incorporating heavier armor, wider tracks, two-way radio, and a modern high-velocity 75-mm weapon, are likely to be encountered in the near future. There is every reason to believe the Japanese are conversant with details of modern German tank design, and that they have also had opportunity to study Allied armor.

Much heavier armor plate, or the addition of spaced armor to the present armor of Japanese tanks, is to be expected. To conform to modern European tank standards, it will have to be up to 40-mm thick on light tanks, up to 75-mm on medium tanks, and up to 100-mm on heavy tanks.

Among other developments anticipated are the use of wider tracks, employment of a modern, high-velocity 75-mm field piece as a tank weapon, two-way radio communication, improved vision, escape doors, and gas-fume extraction.

It must be remembered, however, that while the Japanese are considered capable of designing an efficient modern heavy tank, they may have considerable difficulty in producing such a tank in large quantities.

At present there are four main types of Japanese armored fighting vehicles: tankette (Keisokosha) up to 5 tons, light tanks (Kei Sensha) 5 to 10 tons, medium tanks (Chu Sensha) 10 to 20 tons, and heavy tanks (Ju Sensha) over 20 tons.

Few tankettes have been encountered since the 1942 Burma campaign. There is nothing to indicate, however, that this type has been abandoned and it will no doubt be encountered in operations in open terrain. It is important to realize that the tankette is not intended primarily for fighting but is essentially a light, full track reconnaissance vehicle.

The Japanese light tank most often encountered is the Model 2595 (1935), the design of which seems to have been frozen about 1937 to permit mass production. It was built to operate over the varied terrain of east Asia where roads are few and poor, and where maneuverability is the essential requirement.

The only Japanese medium tank so far encountered is Model 2597 (1937) and its improved versions. Like the Model 2595 light tank, this design also was frozen several years ago to permit mass production. Model 2597 armor is too light for tank-vs.-tank combat, but the vehicle has fair striking power, good cruising radius, and is conspicuously maneuverable. Although the Japanese describe it as "the main striking power of the Army," it has given a poor account of itself in close combat with allied antitank weapons and tanks on various Pacific islands.

Another type now being encountered in the Pacific theater is a light amphibious tank, described in detail in Tactical and Technical Trends, No. 50. General characteristics of Japanese tanks may be summarized briefly as follows:

Only air-cooled Diesel engines are employed. These are 4, 6, and V–12 types, all of which employ the German (Robert Bosch) type of fuel injection.

Basic designs are good, but the tanks are difficult to produce in large numbers. The cooling systems used are likely to give trouble after prolonged use in hot climates.

Transmissions are conventional in design and of sturdy construction. A comparatively large number of nonfriction bearings are used.

The same basic suspension is used in all types so far encountered. Four-point hull suspension bogies are bell-crank mounted to armored compression springs. A trailing idler appeared in later models, resisted by a compression spring. A single bogie roller with unarmored compression spring has been added to each corner of medium-tank hulls.

Tracks are of conventional design and rather narrow. However, loading is light, generally in the neighborhood of 7 to 8 pounds per square inch. Power-weight ratios are excellent throughout the line.

ARMOR GOOD, BUT LIGHT

Japanese armor so far encountered has been of good quality but comparatively light by European or American standards. Arrangement of the armor is poor by modern standards of design. Little use is made of angles and, in many case, reentrant angles are formed. No steps have been noted to protect turret rings or mantlets against jamming or splash.

Hull design can be considered good by modern standards, and the latest models have shown improvement. In some cases crew compartments are very cramped and little attention has been paid to crew comfort. Turrets and hulls are both well insulated with some material, such as asbestos.

For several years all Japanese turrets were circular. More recent models have turrets of oval shape and in some of them a machine gun is mounted coaxially with the main armament. No evidence of power-operated turrets has yet been found.

Periscopes are not frequently used, vision being dependent on slots, occasionally backed by glass blocks.

Apparently little thought has been given to providing the crew with a quick means of escape in case of fire or other emergency.

These weapons have been found in Japanese tanks: Model 91 (1931) 6.5-mm tank machine gun; Model 97 (1937) 7.7-mm tank machine gun; Model 94 (1934) 37-mm tank gun; Model 98 (1938) 37-mm tank gun; Model 1 (1941) 37-mm tank gun; Model 90 (1930) 57-mm tank gun; Model 97 (1937) 57-mm tank gun; and an adaptation, model unknown, of Model 1 (1941) 47-mm antitank gun.

Model 91 is a variation of the standard light machine gun of the same caliber, fitted with telescopic sights, special stocks, etc. All other weapons listed are low-velocity types, with the exception of Model 1 (1941) 37-mm tank gun and the new 47-mm gun, which are mounted in the newer light and medium tanks. However, these low-velocity models may be given a new lease on life by providing them with hollow-charge ammunition, which is reported under development. Weapons are usually arranged in a conventional manner, with one machine gun fore in the hull and the other in the turret opposite the main armament.