IJA Armoured Vighting Vehicles

[tom]

Hi.

7) Armored Cars part 1

IJA and IJN used different types of domestic and foreign armored cars from 1920 on. They were used for armored support of the infantry during long-range operations and street fights even if the armor wasn´t satisfying and the mobility on non-paved roads and off-road was quite poor. Most armored cars were removed from active service after the first domestic tanks became avaliable from 1933 on. Informations on these vehicles are quite rare.

Only railway units used armored cars for railroad security and protected transport until 1945. These will be covered in a later post.

a)Austin and Austin-Putilov Armored Car:

In 1919 IJA bought two second series Austin Armored Cars in Great Britain to equip the units operating with the international force during the Siberian Intervention. This operation was started in 1917 to support the White Russian forces against the Bolsheviks and the german army and to protect the massive stockpiles of supply and ammunition sent by the Entente to Vladivostok. IJA joined in mid 1918, mainly to expand their territory north of Korea.

The Austin Armored Car was desiged in 1914 by the Austin Motor Company based on a serial production truck chassis after the british army requested an armored vehicle with closed fighting comparment, two seperate MG turrets and a good mobility even on non-paved roads. In 1915 the second series was started with a stronger 50 hp engine. The drivers cabin was remodelled to allow the parallel mounted turrets to fire staight ahead and the basic armor was increased from 3,5 - 4 mm to 4 - 7 mm.

The japanese vehicles were delivered until late 1919. After the crews were trained the vehicles were shipped to Vladivostok. At this time the main purpose of the allied troops changed towards fighting off the advancing Bolshevik troops to allow an organised disarming of the beaten White Russian forces to save their equipment from falling into the enemies hands.

Among tons of rifles, ammunition and other equipment several russian Austin-Putilov Armored Cars were handed over to the Entende troops. Some of these vehicles were taken over by IJA.

This vehicles are remodelled second series Austin ACs. Russia ordered 60 of the truck chassis which were delivered in 1916. At the Putilovski Works in St. Petersburg the vehicles received stronger 60 hp engines and a rear drivers position was added. The (in driving direction) left turret was moved to the rear to allow both turrets to fire at the same side at the same time. Two armor plates were added to both sides of the MGs to protect the cooling water tanks around the barrels.

After the end of the Siberian Intervention IJA used the vehicles during various operations which results in the occupation of Manchuria in 1929. The further fate of the vehicles is unknown.

In the mid-1920th the armor from one Austin AC was removed an mounted on a domestic 6 X 4 truck chassis, but there was no serial production.

Data (Austin AC / Austin-Putilov AC)
vehicles bought/captured: 2 / unknown, but less than 10
battle weight: 4,5 (metric) t early version, 4,7 (metric) t late version
crew: 4 men / 5 men
armor 4 - 7 mm
length: 4800mm
width: 2030 mm
height: 2450 mm
engine: Austin 4-cylinder inline gasoline / russian 4-cylinder inline gasoline
power: 50 hp/ 60 hp
maximum speed: 50 km/h on roads / 60 km/h on roads
range: 200 km
Power/weight ratio: 11,1 HP/t / 12,75 hp/t
armament: 2 X 7,7 mm Hotchkiss MG / 2 X 7,62 mm Maxim M1910 MG

b) early Domestic Armored Cars:

experimental light armoured car, based on a 1,5 t commercial light truck chassis, only one known prototype

Besides the Austin Armoured Cars IJA used several experimental domestic armoured cars during the Siberian Intervention based on several light, medium and heavy truck chassis. They were only lightly armoured with the face-hardened armour plates riveted on a frame. All had a rotating turret on the fighting compartment armed with a Type Taisho 3 6,5 mm MG. The heavier vehicle also had several gun ports in the vehicle sides and rear.

experimental medium armoured car, based on a 3 t commercial truck chassis, at least 2 prototypes were built

The armor was only able to defeat ball ammunition but was penetrated by AP ammunition. In addition the off-road mobility was poor. Nevertheless the vehicles were used with some success during the operations and so the decision was made to continue development. Further data are unknown.

experimental heavy armoured vehicle, based on a 4 t commercial truck chassis, at least 2 prototypes were built

No further data, sorry.

c) Renault Armoured Car:

experimental Renault AC with prototype fighting compartment armour

In 1928 IJA bought a Renault 6-wheel 2,5 t truck and developed a modern armour around the vehicle. The vehicle had a drivers position in the bow and in the rear. Armament consited of a Type Taisho 3 6,5 mm MG in a conical turret. In 1929 several trials and tests were made at IJA Cavalry School. In 1929 IJA also bought a Renault prototype of an armoured car based on the same chassis. Both vehicles were used in Manchuria at least in 1929.

No further data avaliable.

d) Type Crossley Armoured Car (Vickers Crossley Model 1925 Armoured Car):

From 1925 on IJA and IJN bought some 12 Vickers Crossley Model 1925 Armoured Cars and used them for infantry and cavalry training. During the late 1920th incidents in Manchuria and northern China the vehicles were used with good success for patrol duties and infantry support.

The vehicles were of standard serial production. The Crew consisted of forward and reverse driver, gunner and commander. The armor strength was 4 - 5,5 mm. Armament consisted of two Vickers 7,7 mm MGs which could be mounted in four gun ports inside the hermispherical turret.

Official designation was “Type Crossley Armoured Car” but western sources also use “Dowa Armoured Car” which is (afaik) caused by a misinterpretation of japanese newspaper reports. The IJN vehicles were stationed in Shanghai for protection of the japanese settlement. The vehicles were used extensively during the 1932 Shanghai Incident. Until 1937 they were replaced by domestic light tanks or tankettes. The final fate is unknown

Data:
vehicles bought: 12
battle weight: 4,85 t
crew: 4 men
armor 4 - 5,5 mm
length: 5020mm
width: 1870 mm
height: 2580 mm
engine: Crossley 4-cylinder inline gasoline
power: 50 hp
maximum speed: 64 km/h forward, 8 km/h reverse
range: 200 km
Power/weight ratio: 11,1 hp/t
armament: 2 X 7,7 mm Vickers MG

e) Wolseley Armored Car / Simple Armored Car:

In 1928 IJA ordered Isuzu to develop an armored car based on their licence-built Wolseley CP 1,5 t truck chassis. The Vickers-made armour of the Type Crossley AC was taken as basis for the armour scheme. The side extensions of the fighting compartment were removed as they were unnecessary due to the smaller turret. Armament consisted of a Type Taisho 3 6,5 mm MG. The vehicles were operated by a forward and a reverse driver, a gunner and a commander. First reported use of this vehicles was during a 1930 cavalry exercise at Mount Fuji Training Ground. At least two vehicles were built.

The official designation is unknown, some IJA source refere to it as “Simple Armored Car” while most western sources use “Wolseley Armored Car” or even “Vickers Wolseley Armoured Car” due to the copied armour scheme. No further details known.

The vehicles weight of 4,2 t was quite large for a 1,5 t truck chassis so it can be assumed that it had serious problems with the weight of the armour. In addition the engine power of 30 hp was quite weak for such a vehicle making it clumsy.

Data:
vehicles built: at least 2
battle weight: 4,2 t
crew: 4 men
armor 6 mm
length: 5562mm
width: 1892 mm
height: 2615 mm
power: 30 hp
maximum speed: 40 km/h forward, 8 km/h reverse
range: 200 km
Power/weight ratio: 7,1 hp/t
armament: 1 X Type Taisho 3 6,5 mm MG

to be continued in part 2…

[tom]

7) Armored Cars part 2

f) Osaka Armored Car:

This vehicle was seen during the 1932 Shanghai Incident operated by naval troops. But it was designed by Osaka Army Arsenal from a domestic 2,5 t truck chassis. The armor sheme was similar to the Wolseley Armored Car but built with thicker armor plates. The turret was slightly larger. Armament consisted of one Type Taisho 3 6,5 mm MG in the bow and a second in the turret.

It seems that only one prototype was built as technology test vehicle. The official designation is not known but european sources from 1935 used “Osaka Armored Car” which would fit to the earlier designation system. Today the vehicle is mostly designated “Hokoku-Go Armored Car” but this is a misinterpretation of the writings on the vehicle during the 1932 Shanghai Incident. “Hokoku-Go” or “Hokoku” was a donation organisation which supported IJN with money and military goods. So it seems that the vehicle was bought by Hokoku after the test trials were finished by IJA and then donated to IJN.

Data:
vehicles built: 1
battle weight: 5,85 t
crew: 4 - 5 men
armor 8 - 11 mm
length: 5000 mm
width: 1850 mm
height: 2650 mm
ground clearance: 280mm
engine: 4 cylinder gasoline
power: 35 hp
maximum speed: 60 km/h forward, 7 km/h reverse
Power/weight ratio: 6 hp/t
armament: 2 X Type Taisho 3 6,5 mm MG

g) Chiyoda Armored Car:

This is the first domestic armored car which was officially introduced by IJA and used in larger numbers. Design started in 1930 at the Chiyoda Motor Car Factory of Tokyo Gasu Denki K. K. (Tokyo Gas and Electric Industries, today Hino Motors Ltd.) based on their Type Q 6-wheeled truck under the development designation "Type QSW. The basic armor scheme was similar to the Wolseley Armored Car. The spoked wheels with pneumatic tired were replaced by disk wheels with fixed rubber bands. The turret had a cylindrical base with a sloped (in driving direction) right upper part. A standard MG mount was placed in this sloped part for air defence. Another MG mount was placed in the turret front and a third in the left bow. In addition three gun / visor ports were placed along each side of the fighting compartment. The standard crew consisted of driver, three gunners and a commander. Armament was three Type Taisho 11 6,5 mm MGs, later three Type 91 6,5 Tank MGs.

The development was finished in 1931 and the vehicle was officially adopted as "Chiyoda Armored Car. In western literature the vehicle is often designated “Aikoku Armored Car” which is a misinterpretation of the writings on a vehicle used during the 1932 Shanghai Incident. This writing referes to “Aikoku-Koto” = “Public Party of Patriots”, a nationalistic and militaristic political party which donated money and military material to IJA (as Hokoku did for IJN).

Around 200 Chiyoda Armored Cars were produced and used during several early and mid 1930th IJA operations in northern China for infantry support and security duties in captured regions. They were replaced after 1937 by the Type 97 Tankette Te-Ke.

Data:
vehicles built: ca. 200
battle weight: 5,6 t
crew: 5 men
armor: unknown, most likely up to 6 mmm
length: 5000 mm
width: 1900 mm
height: 2600 mm
engine: 4 cylinder gasoline
power: 75 hp
maximum speed: 60 km/h
Power/weight ratio: 13,4 hp/t
armament: 3 X Type Taisho 11 6,5 mm MG, later 3 X Type 91 6,5 mm Tank MG

h) Sumida Model P Armored Car:

This armored car was built in 1930 or 1931 by Ishikawajima Heavy Industries at their Sumida Motor Car Factory based on an own 2,5 t 6-wheeled chassis. It was most likely developed as competitor of the Chiyoda Armored Car. The vehicle had a similar basic armor scheme. The turret was cylindrical with only one MG port in the front. The crew consisted of driver, two gunners and commander. Only one or two of these vehicles were built designated “Sumida Model P Armored Car” .

During the 1932 Shanghai Incident one vehicle was donated by the Hokoku organisation to IJN with the writing “Hokoku” on it. Therefore the vehicle is often wrongly designated “Hokoku Armored Car” in western literature.

In Shanghai few additional soldiers were loaded depending on the orders. At this time the basic armament consisted of one Type Taisho 3 6,5 mm MG in the turret and one Type Taisho 11 6,5 mm MG in the bow. The further fate is unknown.

Data:
vehicles built: 1 or 2
crew: 4 men
armor: up to 6 mmm
engine: 4 cylinder gasoline
armament: 1 X Type Taisho 3 6,5 mm MG, 1 X Type Taisho 11 6,5 mm MG

i) Type 93 Armored Car:

This vehicle was developed by Ishikawajima Heavy industries at the Sumida Motor Car Factory in 1932 for IJN. It was based on an european 6-wheeled truck chassis as the drivers position was on the left. In addition the engine compartment was very long which was untypical for contemporary japanese truck designs. The crew consisted of driver, two gunners and commander. A small fighting compartment was placed on the rear axles. The turret was cylindrical with an extension with sloped front for the turret MG. Additionaly one MG-Port was placed on each side of the fighting compartment and on the right in the bow. Armament consisted of a Vickers 7,7 mm MG in the turret and four Type Taisho 11 6,5 mm MGs.

It seems that this vehicles were specially built for street fightings following the lessons learned during the Shanghai-Incident in 1932. The 5 vehivcles built were all used by the Shanghai Special Naval Landing Force from 1933 on for security duties inside the european and the japanese settlements in Shanghai.

Official designation was “Type 93 Armored Car” but in western literature it is often wrongly designated “Type 92 Armored Car” for the development year. In addition it is often mixed up with the Sumida Model P Armored Car.

Data:
vehicles built: 5
battle weight: 4,5 t
crew: 4 men
armor: unknown
length: 4800 mm
width: 1800 mm
height: 2300 mm
maximum speed: 40 km/h
armament: 1 X Vickers 7,7 mm MG, 4 X Type Taisho 11 6,5 mm MG

Yours

tom!

[tom]

Hi.

8) Tankettes part 1

a) Type 94 tk Special Tractor:

first prototype

The 1930/31 trials with the Carden-Loyd Tankette showed the value of small armored tracked transport vehicles for battlefield supply, reconnaissance and liaison duties. So the decision was made to develop a domestic tankette.

In 1933 requirements were given:

• maximum weight 2,65 t
• maximum speed 45 km/h
• trench crossing abilities 1,5 m
• size up to 3400 mm (l) / 1620 mm (w) / 1540 mm (h)
• 2 men crew
• engine placed in the bow to gain maximum storage room in the rear
• driver placed next to the engine
• welded face-hardened armor with a maximum strength of 12 mm, able to defeat infantry AP ammunition
• small revolving turret with machine gun
• good cross-country abilities
• center-guide type tracks
• use of an air-cooled 4-cylinder gasoline engine
• steering system fixed radius with controlled differential
• large rear access door
• towing bar on the rear with a towing capacitiy of up to 1000 kg

In addition requirements for a trailer to be towed by the tankette were given:

• 750 kg payload
• tracked
• minimised height

Tokyo Gas and Electric K.K. (a. k. a. Gasuden, today Hino Motors) was chosen for development in early 1933. They developed a seesaw-type suspension system with two pairs of roadwheels connected by a large horizontally mounted coil spring on each side. The roadwheels were connected by a bell crank. A forward driving wheel, a rear idle wheel and two return rollers completed the suspension. The basic system became standard for all further japanese tanks until 1945.

late prototype with transport trailer

To maximise armor protection the upper frontal armor was arranged sloped. This made an extension necessary for the gearbox, placed in front of the engine. The engine itself was placed on the left, surrounded by a layer of asbestos fiber mats. The driver sat on the right. A quadangular cupola with with visor ports on the sides and the front allowed a good sight. A hatch opening to the front allowed an easy access. A small conical turret with an extension for the Type 91 6,5 mm tank MG´s mount was placed centered on the rear. It also had a hatch opening forward on top. The turret was turned manually by the gunner/commander with the MG stock. The vehicle had a good balance and could easily pushed by few men. but the low weight also led to an instability as weapons platform making aimed MG fire problematic.

The armored trailer had two roadwheels connected with a bell crank between two idle wheels on each side. It had an open top which could be covered by a waterproof canvas. The empty trailer could easily be manhandled.

Test trials started in late 1933 and showed a good manoevrability even in bad terrain. The maximum speed of 45 km/h did also impress IJA officials as they had thought this requirement was too ambitious. Therefore the larger weight of 3400 kg was accepted. But the turret was found too high. So it was remodelled.

After finishing different duration tests the prototype was shipped to Manchuria in spring 1934 and tested under field conditions. It worked fine but the long exhaust pipe to the muffler placed outside the vehicle was critisised as too vulnerable. So the forward part was relocated inside the vehicle. In addition the roadwheels were slightly enlarged for less problems with rocks stuck between them. The instability during firing the MG was found acceptable.

The resulting vehicle was officially adopted as “Type 94 tk” the trailer as “Type 94 3/4 t Trailer”. “tk” stands for “Tokusyu Keninsha” = “Special Tractor”. Serial production was prepared from fall 1934 and started in early 1935. In spring 1935 the first production vehicles were used to built up the first armored transport companies. Some became organic units of infantry divisions, others became independent units which were attached temporarily to infantry units for special operations . A company consisted of 4 platoons with 4 Type 94 tk each, a company headquater with a Type 94 tk, 2 passenger cars and a motorcycle and a company train with 7 trucks. Other vehicles were used to enstrength cavalry and tank recon units, which received 7 vehicles each. The low weight of the Type 94 tk allowed tranport on heavy trucks during longer relocation cruises.

In mid 1935 the first Type 94 tk were send to China were they were used with good success as transport vehicles. But as they often were the only armored vehicles under direct command of the infantry unit they were also often used as armored spearhead, a task they were not built for. But due to the lack of at-weapons in the attacked chinese units losses were only marginal. For this use the instability as weapons platfform became problematic. Therefore the infantry required several changes to increase stability, cross-country abilities and fire power.

The modification works started in late 1936. The rear idle wheel was enlarged and relocated on the ground to enlength track ground contact by 780 mm to 2300 mm. Additionally it was spring mounted with a coil spring for better stability. This also made the use of a Type 94 37 mm tank gun possible. The turret gun mount was modified to make an easy and quick exchange of the MG with the gun and vice versa. This increased the weight from 3400 kg to 3900 kg. The use as transport and towing vehicle was not affected by the changes, even if the transport space was needed for ammunition when using the gun. All changes could also be easily implemented in the already avaliable tankettes. The vehicle was now rerated from armored transport to light armoured vehicle. From 1937 on the Type 91 MG was replaced by the Typpe 97 7,7 mm Tank MG. There were also trials to use a Diesel engine but due to the introduction of the successor not finished.

late version with tank gun. Note the spring system of the idle wheels.

Production numbers were 300 vehicles in 1935, 246 in 1936, 200 in 1937, 95 in 1938 and 1939 an 2 in 1940.

From 1937 chinese forces were more and more equipped with at-weapons and heavy MGs which penetrated the armor easily (the AP-ammunition of the US .50 HMG penetrated the frontal armor on up to 600 m). So losses increased rapidly. Therefore the Type 94 tks were more and more withdrawn from attack duties and used for the intended tasks as transport and recon vehicles.

With the introduction of the Type 97 Te-Ke tankettes the Type 94 tk were withdrawn from the recon units. Transport units used them until surrender.

Special chemical and biological warfare trailers based on the transport version were also developed for spraying and decontamination. The spraying trailer had a conical front. It contained a biological or chemical agent tank and a spraying vent on the upper rear. The decontamination trailer contained a decontamination agent container and a release vent on the lower rear.

spraying trailer

decontamination trailer

In western literature and on the web the early Type 94 tk is sometimes falsely designated “Type 92 Tankette” .

Several special purpose vehicles and some experimental prototypes were made using the chassis of the Type 94 tk, too.

Data (early / late version)
vehicles built: 843
battle weight: 3,4 (metric) t / 3,9 (metric) t
crew: 2 men
length: 3080mm / 3400mm
width: 1700 mm
height: 1620 mm
ground clearance: 290 mm
track ground contact: 1520 mm/ 2300 mm mm
trench crossing capability: 1300 mm / 1600 mm
climbing capability: 35°
maximum vertical obstacle: 500 mm
engine: Type 94 4-cylinder gasoline
power: 32 hp at 1800 rpm
maximum speed: 45 km/h / 40 km/h on roads
fuel capacity: 106 l
range: 500 km on road, 400 km in easy terrain, 200 km in rough terrain
transmisson: 4 forward, 1 reverse
Power/weight ratio: 9,4 HP/t / 8,2 hp/t
armament: 1 X Type 91 6,5 mm Tank MG, later 1 X Type 94 37 mm Tank Gun or 1 X Type 97 7,7 mm Tank MG

armor	strength
turret front	12 mm @ 90 °
sides	10 mm @ 80 °
rear	10 mm @ 80 °
roof	6 mm @ 0 °
superstructure front	12 mm @ 40 °
sides	10 mm @ 90 °
rear	8 mm @ 70 °
top	6 mm @0 °

to be continued in part 2…

[tom]

8) Tankettes part 2

b) Type 97 Light Armoured Vehicle Te-Ke:

prototype

Until late 1936 Ikegai Automobile was able to develop a small light Diesel engine for the Type 94 tk but the size was slightly larger than the size of the gasoline engine. Therefore the length of the vehicle had to be increased which complicated the internal crew communitation. A touch code was used for this as the engine noise made voice commands impossible and the use of contemporary earphones was problematic due to the vibrations. . A trial prototype was tested from early 1937 on. It had a much larger ventilation and engine access hatch than the gasoline version.

The larger engine constricted the driver, too. In addition the frontline troops demanded further changes for reconnaissance duties. So the decision was made to develop a new vehicle. Requirements were:

• use of the same suspension, transmission and steering type
• use of as many suspension part of the new Type 95 Light Tank Ha-Go to simplify maintainance
• relocation of the Diesel engine
• increase of frontal armor to 16 mm
• use of welding wherever possible

The prototype was finished in September 1937. Engine and driver changed the side and the engine was shifted slightly to the rear but the stroke was still limited due to the avaliable height which limited the engine power. Due to this relocation the gearbox could be relocated, too, making an extension in the frontal armor unnecessary. In addition the vertical lower frontal armor cold be replaced by a curved casted armor plate. The flat turret hatch was replaced by a curved hatch making low angle fire easier for the gunner. In addition the roadwheels from the Type 95 Light Tank and a similar driving wheel were used. Innitial tests showed that the noise and heat emission of the engine was larger than from the gasoline engine which was found inacceptable. So the design was changed again from November 1937 on.

The engine was now placed lengthwise in the rear inside a separated compartment. The turret was shiftet to front and the rear access hatch was removed. Therefore the vehicle was no longer able to transport supply inside. But the towing bar was still attached. Additionally the armor above the drivers seat was remodelled and streamlined. The drivers hatch was removed. So access to the fighting compartment was now only possible through the turret hatch.
The turret was now partly welded and an acccess hatch was added to the rear mainly to simplify ammunition supply. The gun could still easily be exchanged with the MG.

The innitial factory tests were finished in early 1938 and the vehicle was handed over to IJA Infantry School for field test. In mid 1938 the vehicle was officially adopted as Type 97 Light Armored Vehicle Te-Ke. Production started in early 1939 with 271 produced in 1939, 284 in 1940 amd 41 and 38 in 1942. Production was stopped in 1942 to shift the raw materials to the production of the Type 97 Medium Tanks and aircraft.

serial production vehicle

The Type 97 Te-Ke replaced the Type 92 Heavy Armored Vehicles and the Type 94 tk in the infantry and cavalry recon units and was used with good sucess as armored recon vehicle. In the later stages of the war the vehicles were als used for infantry support and against tanks with less success due to the small gun with its bad penetration and poor HE-power.

Data (MG / gun version)
vehicles built: 593
battle weight: 4,5 (metric) t / 4,75 (metric) t
crew: 2 men
length: 3700 mm
width: 1990 mm
height: 1790 mm
trench crossing capability: 1600 mm
maximum vertical obstacle: 810 mm
engine: Ikegai OHV Series 4-cylinder Diesel
power: 65 hp at 2300 rpm
maximum speed: 40 km/h on roads
fuel capacity: 240 l
range: 250 km in easy terrain
transmisson: 4 forward, 1 reverse
Power/weight ratio: 14,8 HP/t / 13,6 HP/t
armament: 1 X Type 97 7,7 mm Tank MG / 1 X Type 94 37 mm Tank Gun
ammunition: 2800 shots for MG or 102 grenades for gun

armor	strength
turret front	16 mm @ 80 °
sides	16 mm @ 80 °
rear	10 mm @ 75 °
roof	6 mm @ 0 °
superstructure front	12 mm @ 40 °
sides	10 mm @ 90 °, upper part @ 45 °
rear	8 mm @ 70 °
top	6 mm @0 °

Yours

tom!

[tom]

Hi.

9. Light Tank part 1:

a) Type 95 Light Tank Ha-Go part 1 :

early prototype

After introduction of the next generation trucks in the early 1930th with their maximum speed of 60 km/h IJA deployed a mechanised brigade at Kungchuling/Manchuria in early 1933. This unit consisted of mechanised infantry, artillery and support units plus a company-sized tank unit. Main task was to develop tactics for mechanised units. During the first exercises the avaliable Type 89 tanks with their maximum speed of 25 km/h were not able to follow the fast moving infantry. This was found unacceptable. But several members of IJA High Command weren´t convinced that the japanese heavy industry was able to develop a tracked vehicle with the planned maximum speed of 40 km/h

So IJA Technical Headquaters started a mobile tank development program. First choice seemed to be a wheelcumtrack-vehicle. But first studies indicated that this technology was still very complex and expensive and with the avaliable financial budget a successful introduction was not too sure. The new advanced Christie-suspension was also taken into account but the expected costs for licence and development seemed too high, too. With the success of the new Type 92 Heavy Armored Vehicle for the cavalry the decision was made to built a conventional tracked vehicle instead.

In July 1933 the requirements were given to Army Technical Bureau:

• maximum speed 40 km/h
• maximum weight 7 t
• 3 men crew of driver, commander-gunner and machine gunner-technician
• armament: long 37 mm gun in a revolving turret and bow MG
• face-hardened armor, available to defeat infantry AP-ammunition, maximum strength 12 mm
• use of welding as much as possible
• access through a hatch on the turret
• size up to 4300 mm (l) X 2000 mm (w) X 2280 mm (h)
• use of an air-cooled Diesel engine, placed in the rear right
• engine compartment separated from the fighting compartment but accessible
• clutch-brake-type transmission with forward driving wheel
• development in cooperation with and serial production by Mitsubishi Heavy Industries

Until June 1934 a prototype was finished. Welding techniques weren´t too advanced so many parts still had to be riveted. The vehicle had two pairs of bogie wheels suspended on a single bell crank with two bell cranks connecting them to a large horizontal spring plus one centered return roller on each side. The spring was covered by a hemispherical armor plate. The bow and partly the rear armor were arranged angled, the side armor was vertical. The driver sat on the right (in driving direction). He operated the tank using levers for the track breaks and reduction gears. The bow gunner/technician sat on the left of the driver operating a Type 91 6,5 mm Tank MG in a standard mount. The turret was slightly conical with an extension for the gun. A small two door access hatch in the rear allowed easier ammunition supply. All crew members entered the tank through a large hatch on top of the turret. The commander had to observe the battlefield, to operate the gun, and to turn the turret. Turret traverse was done by turning a small handwheel operating gear wheels in a gear ring. Internal communitation was wire-based with simple headsets.

A small hatch on the upper rear armor allowed service access for the rear engine parts. A large hatch with cooling air intakes on the upper armor allowed engine exchange.

Basic tests including a 700 km endurance trial were finished until October 1934 with good success. The requirements were met including a maximum road speed of 43 km/h and an operational range of 250 km. Only the weigth of 7,5 t was slightly too high. Therefore the armor was modified by slightly decreasing its strength in less vulnerable areas. The armour in front of the driver was now curved and could now be opened to the top for a better view and ventilation. The result was a vehicle with a weight of 6,5 t and a maximum speed of 45 km/h archieved during a second 370 km endurance trial.

The tank was sent to Cavalry School in October 1934 and tested intensely. The results were very good and an immediate introduction as replacement for the quite weakly armed Type 92 Heavy Armored Car was suggested. The prototype was then handed over to Infantry School for further tests. There the power of the Type 94 Tank Gun and the 12 mm maximum armor were rated weak making the tank not really suitable for the contemporary IJA tank doctrine to use tanks for infantry support. Nevertheless the tank was sent to Manchuria in late 1934 for climatic and practical tests. These included maneuvers with a mixed mobile brigade for fast assaults. There the tank showed a very good performance especially in very cold climate and the speed was rated useful for fast assaults. Therefore the infantry branch also requested an immediate introduction.

Second prototype

From June until November 1935 a second prototype was built implementing several small changes suggested after the tests. Stronger sprockets and span wheels were mounted and a second return roller was added to the suspension for more stability. The bow gunner received an armor extension for better handling and engine access was designed easier. In addition special bogies with two small wheel placed between the road wheels were designed to prevent Kaoliang plants which were quite common in northern China and Manchuria pitching them when they get between them. This modification was called “Manchurian Suspension”. These were replaced by the standard bogies when tank units left Manchuria for other operational areas.

The vehicle was officially introduced in late November 1935 after few very successful tests as “Type 95 Light Tank” and the internal Mitsubishi development designation “Ha-Go” was adopted officially as short designation. Before start of mass production in mid-1936 more changes were made to increase the combat abilities. The vertical side armor was improved by adding conical hemispheric armor extensions above the tracks to the fighting compartment for a better armor protection and to increase ammo capacity. In addition the upper side armor above the engine was arranged angled and large cooling hatches with vertical slats were added there. The bow gunners armor extension was remodeled and enlarged. An observation cupola with a two-piece hatch replaced the original hatch on the turret. A Type 91 Tank MG facing in 5 o´clock direction was placed in an armor extension on the rear turret to still have firepower in case of a damaged gun (not for close defense). The suspension received standardised road wheels and easier to produce driving sprockets and idle wheels. The weight was now 7,4 t which was accepted.

Production vehicle with manchurian suspension captured by soviet troops during the Nomonhan Incident

Due to budgetary problems and the low priority for raw materials for tank production serial production started with low numbers at Mitsubishi:
1936: 31
1937: 80
1938: 53
1939: 115
After the Nomonhan Incident and because of the ongoing China-Incident (as the 2nd Sino-Japanese War was called in Japan) with the intensified support of the chinese government by USA, GB and France military budget and priority of tanks were increased boosting the tank production numbers:
1940: 422
1941: 685
1942: 755
1943: some 234
Due to too low capacities at Mitsubishi Niigata Tekkosho, Kobe Seikosho and Kokura Army Arsenal also started to produce this tank during this periode. In mid 1943 production was stopped mainly to increase the production numbers of the Type 97, Type 1 and Type 3 Medium Tanks. With a total production of ca. 2375 vehicles the Ha-Go was the most numerous japanese armored vehicle.

to be continued in part 2…

[tom]

9) Light Tanks part 2

a) Type 95 Light Tank part 2:

Few vehicles were equipped with a thin handrail-type antenna on the turret and wireless communcations equipment (Type 94 Radio) to be used as command tanks.

Type 95 Ha-Go with antenna

The first operational unit equipped with the Type 95 Light Tank was the tank unit of the Independent Mixed Brigade which received their vehicles in late 1936. First operational use was during the innitial stage of the China Incident at Shansi Province against a retreating enemy. There the tank showed its value as scout tank pursuing the enemy.
It was planned to equip each tank battalion with a light tank company consisting of 13 Type 95 Ha-Go (Command section with one tank and 4 platoons with 4 tanks each). In addition each medium tank company should receive 2 light tanks for the command section and the cavalry recon units should replace their Type 92 Heavy Armored Vehicles with this tank, too. However production numbers were too low to archive this goal especially with the increasing losses after 1939.

After 1937 the Type 91 Tank MGs were replaced by Type 97 7,7 mm Tank MGs and the Type 98 37 mm Tank Gun replaced the Type 94 37 mm Tank Guns.

The tank units of the IJN Special Naval Landing Forces received several Type 95 Light Tanks and used them for garrison duties on several pacific islands. The siamese army also bought some of these tanks.

siamese Type 95 Ha-Go

The Type 95 Light tank was very successful as scout tank especially during the innitial stages of the war against the western allies. During the 1941/42 Malaya campaign these tanks put a high preasure on the retreating Commonwealth units making it almost impossible for them to regroup and build up a successful defence line. They also made the fast success against the ABDA-forces in Duch East-India possible. During the 1941/42 Philippine and Burma campaigns they also did a good job but suffered losses from the US M3 Light Tanks which penetrated them easily on longer ranges while they had to get close to penetrate them. This and the 1939 Nomonhan campaign showed that they were not suitable against modern contemporary light tanks. But they were never intended to fight enemy tanks.

All successes after 1940 were against an inferiour or badly leaded enemy which concealed that the tank was in fact outdated. Many commanders were very pleased with the tank and saw no need for a new design. This lead to the wrong decision to refuse an already production-ready modern successor and even to prohibit further developments to spare ressources until 1944. So in 1944/45 the Type 95 Light Tanks had to withstand tanks and anti-tank weapons which were designed 5 to 8 years later and were easily slaughtered.

After the war few Type 95 Ha-Go with additional armour plates around the turret front and side (ordered by the commanding officer of the japanese unit they belong to) were taken over and used by french colonial forces in Indochina and used until 1948. The additional armor plates had a thickness of 10 mm and were mounted spaced on the turret front and on the bow extension for the MG-gunner/radioman.

Type 95 Ha-Go used by french troops

Data
vehicles built: ca. 2375
battle weight: 7,4 (metric) t
crew: 3 men
length: 4830 mm
width: 2070 mm
height: 2280 mm
ground clearance: 390 mm
track width: 251 mm
ground pressure: 0,63 kg/cm²
trench crossing capability: 2000 mm
climbing capability: 40°
maximum vertical obstacle: 600 mm
engine: Mitsubishi A6120VD 6-cylinder Diesel engine
power: 120 hp at 1800 rpm
maximum speed: 40 km/h on roads, 28 km/h cross-country
fuel capacity: 164 l
range: 248 km on roads
transmission: 4 forward, 1 reverse
Power/weight ratio: 15,6 hp/t
armament: 1 X Type 94 37 mm Tank Gun , 2 X Type 91 6,5 mm MG, later 1 X Type 98 37 mm Tank Gun and 2 Type 97 7,7 mm Tank MG
Ammunition capacity: 119 37 mm grenades, 2940 MG shots

armour	strength
turret front	12 mm @ 80 °
sides	12 mm @ 80 °
rear	12 mm @ 90 °
roof	6 mm @ 0 °
structure front	12 mm @ 70 °, upper part @ 78 °
sides	12 mm @90 °, upper part 10 mm @ 45 °
rear	8 mm @ 90 °, upper part 8 mm @ 30 °
top	10 mm @ 0 °

to be continued in part 3…

[tom]

9) Light Tanks part 3

b) Type 98 Light Tank Ke-Ni:

Despite the IJA High Command´s policy that no new light tank design was necessary Army Technical Bureau started a new development in 1938 as technology test program. Since the beginning of the Ha-Go design in 1933 tank technology and metalurgy had made large progress. Welding techniques were improved and sloped armour was about to become standard. Therefore a completely new tank was designed. As it was a test program no official requirements were given. The decision was made to develop two different types of suspension for comparison tests. Both prototypes should use the same armor body. In addition a new armament consisting of a new 37 mm tank gun and a coaxial MG should be developed. Development orders were given to Mitsubishi Heavy Industries and Hino Motors. Mitsubishi should develop a Christie-type suspension, Hino a suspension based on the Type 97 Medium Tank.

The armour body consisted of a 40° sloped lower bow armor with a casted bow. The superstructure was designed pentagonal with a slope of 80° The forward armor consisted of a small center part which could be opened downward with the driver´s optics. The forward side armor ended above the tracks. Visor ports for the driver increased the view angles to the sides. A pistol port on each side allowed close defence. All driver´s visor ports had bullet-proof glass for protection. The rear side armor had just one opening on the rear right side (in driving direction) for the exhaust pipe. The rear armor had two large ventilation air intakes. On the lower rear armor a large access hatch allowed engine maintainance. A second maintainance hatch was placed on the top armor behind the turret. It was not possible to replace the engine through these hatches. So the complete superstructure could be removed. All armor plates where welded together. Rivets were only used to mount the frames of hatches and visor ports.

lifted superstructure

The engine was placed sidewise in the rear allowing a shorter length of the vehicle. The propeller shaft was placed offset to the left. Maintainance was also possible from the fighting compartment. The driver sat in the center of the tank. He operated the tank with a driving wheel instead of levers. The communication equipment was operated by the commander and consisted of a Type 94 wireless set and a wire-based onboard communication set.

The turret was conical with a large semicircular hatch on top. On each side of the gun mount holes for optics were placed with pistol ports below them. Additional visor ports with gun ports below them were placed on each side and the rear access hatch. Turret crew consisted of the commander/loader on the right side and the gunner on the left side. The turret was turned manually by the commander using a handwheel. This tank was the first japanese tank with a coaxial MG instead of a rear turret MG. The gun mount allowed an elevation of -15° - 25° and a traverse from 5° left - 10° right.

Mitsubishi prototype

Mitsubishi developed a suspension using a licence from Christie. It consisted of four large roadwheels with rubber bands, a rear driving sprocket and a forward idle wheel. The vehicle was designated “Experimental Light Tank Prototype Kou(A)”.

The Hino suspension consisted of 3 pairs of small roadwheels connected by bogies, 3 return rollers, a forward driving sprocket and a rear idle wheel. The two forward roadwheel pairs were connected by a large horizontal spring, the rear pair was attached to the mid pair by a smaller horizontal coil spring. All springs where placed inside the tank. This vehicle was designated “Experimental Light Tank Prototype Otsu”.

In mid 1939 the test trials started. During testing both prototypes reached a maximum speed of above 50 km/h and very good cross-country abilities. Finally the Hino suspension was rated slightly superiour and the Christie system was dropped. Several minor changes were demanded and introduced including a less sloped conical turret for additional turret space and smaller holes for the turret optics. All changes were finished until late 1939. Later the vehicle received the official designation “Type 98 Light Tank Ke-Ni”.

Even if the tank was far superiour to the Type 95 Ha-Go IJA High Command saw no need for a new light tank which would increase the number of vehicles to be supplied. Additionally there were not enough raw materials avaliable for a parallel production of a second light tank model and a change of production would have ment a periode with no tank production which was not acceptable. So the plans and the prototype were stored.

In 1942 after facing the superiour contemporary allied tanks and recognising the reports of the japanese observers about T-34 and KV tanks on the german eastern front the general tank policy was changed from “everything is fine” to “we need better tanks”. So the already about to be outdated Type 98 Light Tank was finally put into production in mid 1942 but with a Type 1 37 mm Tank Gun instead of the Type 100 gun. 87 vehicles were produced in 1942 and 26 more in 1943. Then production was ceased in favour of the more powerful medium tanks.

It was clear that the 37 mm tank gun was generally outdated and not suitable for anti-tank fights. So the production vehicles were rated as scout tanks and issued to homeland defence tank units. An unknown number of vehicles were send to army airborne units to be tested as airborne tanks carried by KU-7 gliders. The project was cancelled in 1944 and the tanks were handed back to tank units.

None was used operationally.

Data
vehicles built: 113
battle weight: 7,2 (metric) t
crew: 3 men
length: 4110 mm
width: 2110 mm
height: 2820 mm
ground clearance: 350 mm
trench crossing capability: 2100 mm
climbing capability: 30°
maximum vertical obstacle: 700 mm
engine: Mitsubishi Type 100 6-cylinder Diesel engine
power: 130 hp at 2100 rpm
maximum speed: 50 km/h on roads
range: 300 km on roads
transmisson: 5 forward, 1 reverse
Power/weight ratio: 18,1 hp/t
armament: 1 X Type 100 37 mm Tank Gun, later 1 X Type 1 37 mm Tank Gun and 1 Type 97 7,7 mm Tank MG coaxial
Ammunition capacitiy: 106 37 mm grenades, 3160 MG shots

armour	strength
turret front	16 mm @ 80 °
sides	16 mm @ 80 °
rear	16 mm @ 90 °
roof	6 mm @ 0 °
structure front	16 mm @ 40 °, upper part @ 60 °
sides	12 mm @90 °, upper part @ 60 °
rear	8 mm @ 65 °, upper part @ 35 °
top	10 mm @ 0 °

c) Type 2 Light Tank Ke-To:

In late 1941 IJA airborne units demanded a tank able to be carried by gliders. So they received several Type 98 Light Tanks in late 1942. After innitial tests an enlargement of the turret was demanded for easier gun handling. So Hino developed an almost cylindrical turret until early 1943.

Due to raw material shortages production of the resulting vehicle could not be started before early 1944. At this time IJA High Command demanded a standardisation of the tracks of light tanks, prime movers and tracked transport vehicles and so the new tracks were added to the design. Shortly after serial production started the glider development program was cancelled and so production was ceased after only 29 vehicles built. All were issued to army airborne units and stored for the expected homeland invasion. None was ever used operational.

Data:
as Type 98 Light Tank Ke-Ni except
Height: 2120 mm
Ammunition capacitiy: 93 37 mm grenades

armour	strength
turret front	16 mm @ 90 °
sides	16 mm @ 90 °
rear	16 mm @ 90 °
roof	6 mm @ 0 °
structure front	16 mm @ 40 °, upper part @ 60 °
sides	12 mm @90 °, upper part @ 60 °
rear	8 mm @ 65 °, upper part @ 35 °
top	10 mm @ 0 °

to be continued in part 4…

[tom]

9) Light Tanks part 4

d) Type 3 Light Tank Ke-Ri:

no pic, sorry

In 1942 IJA started a large program to increase the firepower of its tank force regarding at-power. This included trials to upgun the Type 95 Light Tank. One try was to mount a Type 97 57 mm Tank Gun inside the standard turret of the Ha-Go. 3 vehicles were modified that way and tested in early 1943. Results were unsatisfying as the armour penetration even with HEAT ammunition wasn´t larger than with the Type 98 37 mm Tank Gun. In addition the larger recoil forces damaged the turret ring and gun handling was very problematic inside the narrow turret. Therefore the project was ceased and the tanks rearmed with the standard gun.

Data:
as Type 95 Light Tank Ha-Go except
armament: 1 X Type 97 57 mm Tank Gun

e) Type 4 Light Tank Ke-Nu:

Another try to increase the firepower of the Type 95 Light Tank was to replace the turret with surplus Type 97 Medium Tank Chi-Ha turrets. This was done after the Type 3 Light Tank project was cancelled. For this the turret ring diameter had to be increased from 1000 mm to 1350 mm. The handrail antenna was later removed from the turret as the tank did not have a wireless set.

Tests started in 1944. The modification increased the vehicle weight by 1000 kg making the tank top-heavy and increasing the stress on the suspension. As result the accuracy was decreased and the tanks broke down more often. An additionall armour plate between the bow gunner extension and the driver´s hatch closed a shot trap. With this modification the driver´s hatch couldn´t be opened any more. After several tests the project was cancelled, too. As it was impossible to rearm the 10 converted tanks the decision was made to use them as mobile pillboxes only.

An unknown number of Type 95 Ha-Go were modified the same way by the Kwantung Army in Manchuria at Mukden Army Arsenal. It seems that this conversions were done without official permission. These vehicles can be easily identified by several minor changes compared to the officially converted tanks. Most significant is a slight turret overhang to the left and the missing additional armour plate. One of these vehicles is on display at Kubinka Museum.

Data:
as Type 95 Light Tank Ha-Go except
vehicles built: 10 plus an unknown number of modifications at Mukden Army Arsenal
battle weight: 8,4 (metric) t
height: 2480 mm
ground preasure: unknown
trench crossing capability: 2000 mm
climbing capability: unknown
maximum vertical obstacle: unknown
maximum speed: unknown
range: unknown
Power/weight ratio: 14,3 hp/t
armament: 1 X Type 97 57 mm Tank Gun and 2 Type 97 7,7 mm Tank MG
Ammunition capacitiy: unknown

armour	strength
turret front	25 mm @ 80 °
sides	25 mm @ 75 °
rear	25 mm @ 78 °
roof	10 mm @ 0 °
structure front	12 mm @ 70 °, upper part @ 78 °
sides	12 mm @90 °, upper part 10 mm @ 45 °
rear	8 mm @ 90 °, upper part 8 mm @ 30 °
top	10 mm @ 0 °

f) Experimental Type 5 Light Tank Ke-Ho:

No picture, sorry

first proposal but with a Chi-He turret

With the change in tank doctrine in mid 1942 IJA also ordered the development of a new light tank for reconnaissance and liason duties but with limited priority. Most data of this project were destroyed before surrender but the following is known:

Reqirements were among others:

• maximum armor strength 20 mm
• main armament consisting of a shortened version of the Type 1 47 mm Tank Gun to spare weight and one MG
• crew consisting of driver, gunner, loader and commander/wireless operator
• use of standardised suspension parts

Development started in late 1942 in cooperation with Hino Motors. The decision was made to use the Type 98 Light Tank as basis to speed up development. Two proposals were made. The first was to use a lightened version of the standard suspension of the Type 97 Chi-Ha and an armoured body with the basic scheme of the Type 98 Ke-Ni. The second proposal used the suspension of the Ke-Ni with external springs. The superstructure was also based on the predecessor but positioned further to the rear. Both proposals had a maximum superstructure armour strength of 20 mm and used the standard turret of the Chi-Ha KAI.

second proposal with a Chi-Ha KAI turret and coaxial MG

The development of the main armament started in September 1942 and it was planned to finish the prototype until June 1943. Due to raw material shortages and the low priority it wasn´t done until March 1945. The gun had a slightly shortened barrel and a modified recoil mechanism. Elevation was -15° to 20°, no traverse. With the standard Type 1 47 mm HEAP grenade a muzzle velocity of around 740 m/sec was planned. The project seemed to be ceased. For the secondary armament there were proposals to mount it coaxial, in the right turret side or the turret rear.

Tokyo Gas and Electric (TGE) developed a small, supercharged 6-cylinder in-line Diesel engine with 150 hp and 9300 cm³. It was based on a truck engine introduced in 1937.

A prototype of the tank was finished in mid 1945 armed with a standard Type 1 47 mm Tank Gun. There are no survivng pictures or drawings showing the outer apperance. But the drawing avaliable on the internet showing a vehicle similar to the Type 1 Medium Tank is definitely far from reality.

Data
(without guarantee)

vehicles built: 1
battle weight: 9 (metric) t empty, 10 t battle weight
crew: 4 men
length: 4110 mm
width: 2230 mm
height: 2270 mm
track width: 305 mm
ground contact length: 3000 mm
ground preasure: 0,555 kg/cm²
trench crossing capability: 2100 mm
climbing capability: 34°
fordability: 1000 mm
engine: TGE 6-cylinder in-line Diesel engine
power: 150 hp at 2000 rpm
maximum speed: 50 km/h on roads
fuel capacity: 163 l
Power/weight ratio: 14,8 hp/t
armament: 1 X Type 1 47 mm Tank Gun, 1 X Type 97 7,7 mm Tank MG
Ammunition capacitiy: 90 47 mm grenades, unnknown number of MG shots

armour	strength
turret front	19 mm
sides	16 mm
rear	16 mm
roof	10 mm @ 0 °
structure front	20 mm
sides	16 mm
rear	12 mm
top[td]8 mm /td]

Yours

tom!

[tom]

Hi.

10) Medium Tanks part 1:

a) Type 97 Medium Tank Chi-Ni:

During the development of the Type 95 Light Tank Army Technical Bureau kept an eye on new european tank designs. The development of the british A6 and A7 Medium Tank series showed that the next generation of tanks would be heavier with thicker armor and new tasks will be covered. In addition the low maximum speed of the Type 89 Medium Tank became more and more unsuitable for fast operations which were expected on future battlefields even if the frontline commanders were very satisfied with the vehicle. So in 1936 IJA High Command decided to start the development of a fast medium tank to replace the Type 89 tanks.

At this time the available budget was quite low as IJA had to support many garrison troops in Manchuria and northern China. In addition the parliament was still angry about being by-passed by IJA regarding the foreign politics how to deal with China in the early 1930th and saw no need to increase the military budget. So the decision was made to develop two different vehicle. One should be lightweight, cheap and easy to be built, the other should be heavier and built using modern techniques without having a too harsh look on the costs.

The development order for the cheap tank was given to Osaka Army Arsenal under the designation “Medium Tank Project Plan 2”. The requirements were:

• maximum weight 10 (metric) t
• maximum armor strength 20 mm
• 3 men crew consisting of driver, bow gunner/technician and commander/gunner/loader
• maximum speed 27 km/h
• trench crossing capability 2200 mm, 2400 mm with a ditching tail
• armament consisting of a 57 mm gun and one MG

The prototype was finished in June 1937. The first design used the suspension from the Type 95 Light Tank but is was soon clear that this configuration wouldn’t be able to cope with the weight. In addition the bigger vehicle length made this concept prone to mechanical breakdowns. So another suspension was designed based on the Type 94 Special Tractor. It used four pairs of small roadwheels connected with bogies. Bell cranks connected each two pairs with a large horizontal spring which was covered by a hemispherical armor plate. Three return rollers, a forward driving sprocket and a rear idle wheel completed the suspension. Idle wheel and driving sprocket were the same as used on the Type 95 Ha-Go.

front view

The lower bow armor was negative angled while the upper bow armor was very flat. Two large access hatches in the upper bow armor allowed maintainance of the reduction gears. The superstructure was similar to the Ha-Go but bow gunner and driver changed place. This was necessary due to the limited space inside the vehicle and the position of the driving shaft. The driver sat below a semi-hexagonal conical armor extension with a big viewport in the center plate and a pistol port in each side. The trapezoid viewport had bullet-proof glass for protection and could be opened upward. The tank was operated with levers for track brakes and reduction gears.

The bow gunner operated a Type 91 65 mm MG mounted in a standard mount riveted to a sloped armor plate. Welded semi-hexagonal conical armor extensions were mount over each track to the fighting compartment to enlarge the available space. Each had a pistol port facing to the rear and a third port was placed next to the bow gunner The engine was placed lengthwise in the center behind the fighting compartment. Sloped armor plates covered it from the sides and the rear. On the (in driving direction) right side a large ventilator and access hatch with vertical slats was mounted which could be opened upward. The exhaust pipe left the vehicle below the hatch and let to a muffler on the rear right. A large two-door access hatch on the upper armor allowed engine exchange. A large cooling air intake and access hatch was mounted in the left engine compartment door. The lower rear armor was curved. A short ditching tail was mounted in the center of the rear armor.

rear view

A small conical turret was placed offset to the left behind the driver. It was turned manually by turning a handwheel. One pistol port was on the left of the gun and a second in the rear turret in the access door for ammunition supply. A two-door rectangular hatch and a ventilator were placed on top of the turret. The crew could only enter the tank through this hatch. The space inside the turret was very limited and made gun handling problematic.

During the competitive tests with the “Medium Tank Project Plan 1 prototype” the vehicle showed good maneuverability and handling characteristics. All requirements were not only met but exceeded. The weight limit was undershot so much that vulnerable parts could receive 25 mm armor instead of the required 20 mm and the weight still did not exceed 9,8 t. The maximum speed was 30 km/h with a 135 hp Diesel engine and the trench crossing capability was 2500 mm with tail. The limited internal space was found acceptable. The competitor also met all requirements easily but there were still the budget problems. So in early July 1937 IJA High Command inclined to order the plan 2 vehicle now designated “Type 97 Medium Tank Chi-Ni”. But before the final decision the China Incident broke out. Suddenly budgetary problems were wiped off and the decision was made to order the more advanced plan 1 prototype instead.

The Chi-Ni prototype was scrapped even if it was superior to the Type 95 Light Tank and Army Technical Bureau made the suggestion to replace the Ha-Go with this tank.

Data:
only few data survived the war
vehicles built: 1
battle weight: 9,8 (metric) t
crew: 3 men
armor: up to 20 mm
length: 5260 mm
width: unknown
height: unknown
trench crossing capability: 2200 mm, 2500 mm with tail
engine: Ikegai 8-cylinder Diesel engine
power: 135 hp at 1800 rpm
maximum speed: 30 km/h on roads, 12 km/h cross-country
Power/weight ratio: 13,8 hp/t
armament: 1 X Type 97 57 mm Tank Gun, 1 X Type 91 6,5 mm MG
Ammunition capacity: 60 57 mm grenades, 3000 MG shots

to be continued in part 2…

[tom]

Hi.

10) Medium Tanks part 2

b) Type 97 Medium Tank Chi-Ha part 1:

The prototype development order for the “Medium Tank Project Plan 1” was given to Mitsubishi. Requirements were:

• Maximum weight 13,5 t
• Maximum armor strength 25 mm
• 4 men crew consisting of driver, bow gunner/wireless operator, commander/loader and gunner
• Maximum speed 35 km/h
• Trench crossing capability 2500 mm
• Armament consisting of a 57 mm gun and 2 MG

Until June 1937 the prototype was finished. The first suspension version was also derivated from the one of the Ha-Go. It had 3 pairs of roadwheel with rubber bands. The rear 2 pairs were connected with a large horizontal coil spring by bell cranks. The forward pair was connected the same way with the center pair but a smaller coil spring was used. A forward driving sprocket , a rear idle wheel and three return rollers completed the suspension. idle wheels and roadwheels were not massive to spare weight. The rear return roller was thinner and supported only the inner half of the track.

All armor plates made of face-hardened rolled steel. They were welded together but also riveted to enstrengh the connections. Hatch frames, visor slits and MG ports were riveted on the armor, too. The lower bow armor was angled negative, the upper bow was very flat. The superstructure was arranged angled with a slanting rear part. The driver sat below a semicircular extension in the (in driving direction) left side. A large rectangular visor port protected with bullet-proof glass allowed good sight. The bow gunner operated a Type 91 6,5 mm Tank MG in a standard mount on the right side. The wireless equipment, a Type 94 Radio Set, was mounted in a frame below the MG. An ammunition rack for 30 X 20 shot MG magazines was placed on the right side. Additional ammunition was stored to the rear right of the gunner seat and below the floor plates.

The engine was placed lengthwise in the center behind the fighting compartment. An access hatch allowed maintenance from inside the vehicle. Additional maintenance access hatches with ventilation grilles were placed in the rear superstucture armor. A large access hatch with a large grille for engine exchange and cooling air intake was mounted in the upper rear armor. The fuel rank was placed in the rear of the engine, a 180 Ah battery and a lubricant tank were mouted above it. Exhaust pipes lead to mufflers on the rear mudguards on both sides. The rear armor was arranged curved.

prototype of the command tank version showing the innitial armor sheme

The turret was conical with a large cylindrical commanders cupola in the rear right. He was placed offset to the left behind the driver. A large access hatch with an integrated periscope on the cupola allowed the crew to enter the tank. A short rod antenna was on the front right of the cupola. The tank gun was mounted in the turret front and a standard MG mount was placed in a rear extension in 7 o´clock direction.

During the trials the prototype met the requirements. Maximum speed was 38 km/h with a 170 hp Diesel engine. Even if it was the more potent tank design budgetary problems made it unlikely to introduce it. Then China Incident started in July 1937 leading to a massive increase of the military budget from 500.000.000 Yen to 1.700.000.000 Yen in 1937 alone. So finally the decision was made to introduce this tank, now designated “Type 97 Medium Tank Chi-Ha”. Several changes were demanded regarding suspension, armor and turret.

Driver and bow gunner changed the sides to meet the now standardised IJA layout. The driver´s visor port was remodelled to make production easier and a second hatch to enter the fighting compartment was added above the bow gunner. Therefore the turret changed the side, too. The comander´s cupola was redesigned to lower the height. An unusual two-door hatch was installed. It consisted of a long center rectangular door with one semicircular end and a second door around it with the shape of an open lobster shear. The periscope was placed in the center door. The turret ring diameter was increased to allow the use of larger turrets if upgunning would become necessary. A handrail type antenna around the forward hemispere of the turret replaced the rod antenna for a better communication quality. The wireless equipment was changed to a Type 96 Mark 4 Version Bo Radio Set. Armament now consisted of Type 97 MGs instead of the Type 91 MGs. The exhaust pipes were now protected against bullets and splinters by vertical armor plates.

The suspension should be remodelled to increase stability during firing. Therefore the forward pair of roadwheels was removed. The remaining roadwheels were placed centered and two single roadwheels were mounted forward and in the rear. These were connected with a bell crank and a small diagonal coil spring to each roadwheel pair mounting. A second design used a totally different suspension using a modified Horstmann system similar to the one used on the british Vickers Light Mk VI with partly overlapping roadwheels. Finally the first modification was chosen.

These changes were finished until March 1938 and the second prototype was tested in spring. In summer 1938 Mitsubishi was ordered to built up a production line which was finished until late that year. Production numbers were 25 in 1938, 202 in 1939, 507 in 1940 and 315 in 1941. Several other factories were also ordered to produce this tank in 1939 as Mitsubishi was not able to provide the necessary capacities for a production increase. With the introduction of the Type 1 47 mm Tank Gun it was planned to stop the production of the 57 mm version but Osaka Army Arsenal was not able to build enough weapons to equip all production tanks. So between 1942 and production end in 1944 approximately 400 more Type 97 tanks with short 57 mm gun were produced. In 1944 production was stopped in favour of the superiour Type 1 and Type 3 Medium Tanks and due to increasing raw material shortages. Total production was around 1450 vehicles.

second production version with armour plates above the ventilation and access hatches on the rear sides

The first serial production vehicles were delivered in early 1939. One of the first units equipped with this tank was the 3rd Tank Regiment which used 4 Type 97 Chi-Ha as command tanks during the Nomonhan Incident, one was lost. Each tank regiment should receive 31 vehicles for 3 medium tank companies and a command tank in the command section (each regiment only had battalion size following western standards). The production numbers were high enough to equip each regiment planned but it was nearly impossible to reequip units fast after heavy losses.

From mid 1939 Type 97 Medium Tanks were used on most battlefields including the Pacific Islands. They were main attack force during the Malaya Campaign smashing through several allied defence lines with a total loss of 11 (6 destroyed, 5 damaged beyond possible repair) vehicles during the whole campaign, 14 more were damaged and repaired. During several campaigns in China and Burma these tanks also showed their value as mobile platform and infantry support vehicle. Therefore the tank became basis for a large number of vehicles and the workhorse of IJA armored forces.

During production the tank received a hinged additional armor plate on the ventilation and access hatches on the rear side to increase protection against splinters. This armour plate was later replaced by a hinged spaced armour with sloped upper part. An AA-mount for the (removable) turret MG was added on the rear or the left of the commander´s cupola for at least symbolical fire against attacking aircraft during resting.

On the other hand several confrontations with allied contemporary medium tanks in 1942 and 1943 also showed that armor and armament was insufficient for battles against other tanks. But they were never really intended for this task. Trials to develop 57 mm HEAT projectiles weren´t succesful and so the tank was outdated from 1942. Nevertheless it did a good work against infantry, soft targets and field fortifications.

Type 97 with a special rifle mounted instead of the gun to simulate shooting during exercises

After the japanese surrender several Type 97 Chi-Ha were handed over by US Army to Kuomintang-Forces while the soviet Red Army handed over several vehicles captured in Manchuria to the Chinese People´s Army. Both sides used them with success against each other. Other vehicles left behind in Duch East India were used by the indonesian liberation forces during liberation war.

The Type 97 Medium Tank also participated in the last engagement of IJA against invading soviet units landing hostile on Shimushu Jima (northern Kuriles) 3 days after surrender almost pushing the landing forces into the sea again.

to be continued in part 3…

[tom]

Hi.

10)Medium Tanks part 3

b) Type 97 Medium Tank Chi-Ha part 2:

tank with troop made smoke discharger

Data:
vehicles built: ca. 1450
battle weight: 15 (metric) t
crew: 4 men
length: 5520 mm
width: 2330 mm
height: 2230 mm
ground clearance: 400 mm
track width: 305 mm
ground contact length: 3708 mm
ground preasure: 0,66 kg/cm²
trench crossing capability: 2500 mm
climbing capability: 34°
maximum vertical obstacle: 900 mm
fordability: 1000 mm
engine: Mitsubishi SA12200VD 12-cylinder Diesel engine
power: 170 hp at 2000 rpm
maximum speed: 38 km/h on roads
fuel capacity: 235 l
range: 210 km on roads
transmisson: 4 forward, 1 reverse
Power/weight ratio: 11 hp/t
armament: 1 X Type 97 57 mm Tank Gun , 2 X Type 97 7,7 mm Tank MG
Ammunition capacitiy: 114 57 mm grenades, 4220 MG shots

armour	strength
turret front	25 mm @ 80 °
sides	25 mm @ 75 °
rear	25 mm @ 78 °
roof	10 mm @ 0 °
superstructure front	25 mm @ 78 °
sides	25 mm @ 75 °
rear	20 mm @ 25 °
top	10 mm @ 10 °
suspension front	25 mm @ 42 °
sides	25 mm @ 90 °
rear	20 mm curved

c) Experimental Type 98 Medium Tank Chi-Ho:

only known picture

This tank is still a mystery in literature. It seems that it was developed as technology test vehicle in 1939 to test new ideas for medium tanks including a new armament. The suspension used components of the Type 95 Light tank (forward driving sprocket and rear idle wheel) and of the Type 97 Medium Tank (roadwheels and return rollers). The rear single roadwheel was removed and the spring of the forward roadwheel was mounted with a higher angle. The center return roller was removed and the rear roller mounted in the center instead.

The armor scheme was similar to the Type 97 Chi-Ha but simplified. The driver´s extension was removed and the superstructure was higher. All armor plates seemed to be welded. A smaller Diesel engine was also used so the length could be reduced and there was only one muffler on the (in driving direction) left side. The forward mudguards were enlengthened and the rear mudguards placed higher on the vehicle. A short ditching tail increased the trench crossing ability.

Type 97 Medium Tank Chi-Ha with a modified version of the turret which finally became the Shinhoto turret

Main difference was the turret which was enlarged to house the planned 47 mm tank gun. It was placed centered on the vehicle. The turret had a semicircular front and a box-shaped rear. A large trapezoid hatch on top opening to the front allowed access to the vehicle. A standard AA-mount was mounted on the right of this hatch. There was no rear MG but a modified standard MG mount was placed on the lower left of the gun mount.

The vehicle never left the prototype stage but it seems that the tests lead to the Shinhoto turret and the new armor scheme as used on the Type 1 Medium Tank.

Data:
vehicles built: 1
battle weight: 12,5 (metric) t
crew: 3 men
length: 4750 mm
width: unknown
height: 2300 mm
maximum armor: 25 mm
engine: Diesel engine
power: 160 hp
maximum speed: 30 km/h on roads
Power/weight ratio: 12,8 hp/t
armament: not mounted

to be continued in part 4…

[tom]

Hi.

10) Medium Tanks part 4

d) Type 97 Medium Tank Chi-Ha KAI:

During the first operational use of the new Type 97 Chi-Ha at Nomonhan IJA had to recognise that the avaliable 37 mm and 57 mm tank guns were not able to penetrate the soviet BT-5, BT-7 and T-26 light tanks on average combat ranges. But the soviet 45 mm tank guns easily penetrated the japanese tanks even on longer ranges. So it became clear that a better high velocity tank gun was necessary. Therefore IJA started the development of a 47 mm gun to be used as tank and anti-tank gun in late summer 1939 based on theType 97 experimental 47 mm Anti-tank Gun developed and tested in 1937/38. The expected characteristics (recoil, recoil forces, handling) of this gun made it impossible to use it inside the standard turret of the Type 97 Medium Tank.

So a new larger turret had to be developed. The first design of 1940 was based on the turret developed for the Chi-Ho. It had a semicircular front and a box-shaped rear with a modified MG port on the (in driving direction) lower left side of the gun. A cylindrical commander´s cupola with a two door hatch on top was placed offset to the right in the middle. A turnable periscope was in front of the cupola. A small ventilation hatch with visor slit and pistol port was mounted in each turret side. A large rear access hatch allowed easier ammunition supply. Due to the larger size of the turret the access hatch above the bow gunner position couldn´t be opened any more. Tests were made in late 1940. There the new MG position was found impractical and several details should be modified, too.

tank with new turret and AA-mount

The second design had the frontal MG port removed. Instead a standard MG port was placed on the left side of the rear armor. The rear access hatch was moved offset to the right. The ventilation hatch on the left (gunner) side was replaced by a visor slit only. A large one door access hatch was placed above the gunner´s seat to compensate the missing hatch above the bow gunner. The handrail antenna was relaced by a rod antenna on the left side behind the turret. A standard AA-mount for the rear turret MG was placed in front of the gunner´s hatch. The final turret design had a length of 1930 mm and a width of 1430 mm. The height increase compared to the old turret was 100 mm, the weight increase 500 kg. This was found acceptable. The tank received the official designation “Type 97 Medium Tank Chi-Ha KAI”. It seems that the now popular additional designation “Shinhoto” = “new turret” was first used by IJA tank crews but there is no indication that it was adopted officially.

The final tests were made in fall 1941. At this time additional armor skirts for additional protection of the superstructure sides were used but they were abandoned. After the begin of the war against the western allies IJA tanks had to fight against US light M2 and M3 during the Philippine campaign. The US tanks were also impenetrable for the Type 95 Light Tanks and Type 89 Medium Tanks on average combat ranges (There was just one Type 97 Chi-Ha issued to the IJA tank units used during this campaign). Therefore production start was hurried and first serial production vehicles left the production lines in early 1942. The first tank company equipped with this tanks was sent to the Philippines in April 1942. But at this time US forces had withdrawn to Bataan and Corregidor Island leaving all tanks behind. First operational use of the Chi-Ha KAI was during the assault on the island of Corregidor. One of this tanks landed with the third wave on the island together with two captured Light M3 and two Type 95 Light Tanks. After the US surrender shooting tests showed that the Type 1 47 mm Tank Gun penetrated the frontal armour of the Light M3 easily on 400 m.

US Light M3 after japanese penetration tests with the Type 1 47 mm Tank Gun on the Chi-Ha KAI.

The upgunned Chi-Ha KAI should become standard tank of IJA medium tank companies but Osaka Army Arsenal wasn´t able to produce enough guns even to equip all newly produced tanks. So the 57 mm version was also produced continuously. Several tanks received the new turret but only the Type 97 57 mm Tank Gun was mounted. In mid 1942 new trials were made to increase armour strength but nothing was standardised. Nevertheless several Chi-Ha KAI received additional 25 mm armor plates on the bow and the forward superstructure or arond the turret front (but not both). Between 1942 and 1944 757 vehicles were built. Production was stopped in spring 1944 in favour of the Type 1 and 3 Medium Tanks.

The Type 97 Chi-Ha KAI was the only japanese tank used outside the home islands able to penetrate US medium tanks. The M3 Lee and M4 Sherman could be penetrated frontally on average combat ranges (300 - 500 m). But both could penetrate the japanese tanks even on longer ranges. Late-war US trials showed that the M4A1 was penetrated by the 47 mm gun at 90° below 450 m frontally and below 700 m from the sides. During the US 1944/45 Luzon campaign IJA tankers could damage and destroy several M4 with suicide attacks but this had no impact on the campaign. US after action reports mention several frontal penetrations on 150 m at 75°.

Type 97 Chi-Ha KAI on the island of Corregidor

The Type 97 Chi-Ha KAI was built to fight late 1930th light tanks and he was able to do this. But he lacked armour so he had no chance against early and mid-war light and medium tanks. The gun would have been a good light tank armament until surrender but it was outdated as medium tank armament in 1943.

After the war several Type 97 Medium Tanks Chi-Ha KAI were used by both armies of the chinese civil war. One of these tanks became famous for :

“This is one of the earliest tanks used by the PLA. In the battle for Kamzhou, Communist party member Comrade Dong drove this tank and penetrated deeply into the defences of the Nationalist Army to complete its mission successfully. For this, Comrade Dong was honoured with an award and this tank was given the honourable designation of a “Merit Tank”. In 1949 during the Inauguration Ceremony of the Peoples’ Republic, this tank was paraded in front of the leaders of the Communist Party and the Motherland.”

He is now on display at the Military Museum of the Chinese People’s Revolution in Beijing.

Data:
As Type 97 Medium Tank Chi-Ha except:

vehicles built: 757
battle weight: 15,8 (metric) t
crew: 4 men
height: 2330 mm
Power/weight ratio: 10,76 hp/t
armament: 1 X Type 1 47 mm Tank Gun or 1 X Type 97 57 mm Tank Gun, 2 X Type 97 7,7 mm Tank MG
Ammunition capacitiy: 100 47 mm grenades, 4220 MG shots

armour	strength
turret front	25 mm @ 78 ° curved
sides	25 mm @ 75 °
rear	25 mm @ 90 °
roof	10 mm @ 0 °
superstructure front	25 mm @ 78 °
sides	25 mm @ 75 °
rear	20 mm @ 25 °
top	10 mm @ 10 °
suspension front	25 mm @ 42 °
sides	25 mm @ 90 °
rear	20 mm curved

to be continued in part 5…

[tom]

Hi.

10) Medium Tanks part 5

e) Type 1 Medium Tank Chi-He:

After the Nomonhan Incident IJA first focused on increasing the firepower of its tanks. With the introduction of the Type 1 47 mm Tank Gun in 1941 the focus changed towards increasing the armor strength, too. IJA Technical Bureau was ordered to develop a tank using the suspension of the Type 97 Chi-Ha with a maximal armor strength of 50 mm. The armor scheme should be simplified and welding should replace the rivets wherever possible. Prototype development and production should be done in cooperation with Mitsubishi Heavy Industries. Prototype production started in late 1941 but with very low priority as IJA was still very pleased with the Chi-Ha and Chi-Ha KAI.

The test results gathered with the Type 98 Chi-Ho were used to design the armor. Only flat face-hardened steel plates were used. The driver´s armor extension was removed and the whole frontplate mounted several cm further to the bow. This allowed mounting the access hatch above the bow gunner again. The new standardised Type 100 12-cylinder Diesel engine was longer than the SA12200VD of the Chi-Ha. So the engine compartment had to lengthened and the sloped upper armor had to be arranged flat. The rear armor now consisted of a vertical upper plate and a sloped lower plate. All armor plates were welded together. Only the access hatches, viewports and the bow MG port were riveted on the armor.

rear view of Chi-Ha (left) and Chi-He, note the enlarged engine compartment and the additional armor plate on the turret front

The forward and rear mudguards were also lengthened. A headlight on each forward mudguard replaced the headlight on the upper bow armor. The mesh cover around the mufflers were now rectangular instead of curved. Long rod antenna could be mounted on both sides in front of the exhaust pipe outlets. The vehicle use the riveted turret from the Chi-Ha KAI with 25 mm additional armor plates around the front. A loader placed behind the gunner was added to the crew making it quite tight in the turret.

Due to the low priority the prototype wasn´t finished before June 1943. Due to the thicker armor and the new engine the total weight was now more than 17 t but the stronger engine also increased maximum speed and agility of the vehicle. Comparison tests with the Chi-Ha KAI showed a large superiority of the vehicle now designated “Type 1 Medium Tank Chi-He” and so the decision was made to start a serial production as soon as possible.

The first vehicles left the factory in February 1944 and a total of 155 vehicles were built in this year. It was planned to produce more than 400 of this tanks in 1945 but it was difficult to gather the necessary raw materials. So only few vehicles were finished in 1945. The total production number is unknown but at least 171 Chi-He were built until surrender.

It is not sure if the Type 1 Medium Tank was used outside the homeland. Some sources claim that at least 2 vehicles were used by IJA 2nd Tank Division during the 1944/45 Luzon campaign but this is debated. The rest of the vehicles were issued to the tank regiments of IJA 4th Tank Division for homeland defence. Using the same gun as the Type 97 Chi-Ha KAI the tank was still outdated as medium tank even if the thicker armor was a good step forward. He would have been a good light tank, compareable to the US M5 or the Pz II Luchs. But he came too late and in too low numbers.

One Chi-He was sent to Aberdeen Proving Ground after surrender and scrapped after tests. The fate of the other vehicles is unknown but they were either scrapped or sunk in lakes. There is no vehicle on display or in depots so it can be assumed that all were destroyed.

Chi-He and Chi-Ha KAI bow comparison

Data
vehicles built: ca. 170
battle weight: 17,2 (metric) t
crew: 5 men
length: 5730 mm
width: 2330 mm
height: 2380 mm
ground clearance: 400 mm
trench crossing capability: 2500 mm
climbing capability: 35°
fordability: 1000 mm
engine: Mitsubishi Type 100 12-cylinder Diesel engine
power: 240 hp at 2000 rpm
maximum speed: 44 km/h on roads
fuel capacity: 330 l
range: 210 km on roads
transmisson: 4 forward, 1 reverse
Power/weight ratio: 14 hp/t
armament: 1 X Type 1 47 mm Tank Gun , 2 X Type 97 7,7 mm Tank MG
Ammunition capacitiy: 121 47 mm grenades, 4220 MG shots

armour	strength
turret front	25 + 25 mm @ 72 ° curved
sides	25 mm @ 75 °
rear	25 mm @ 90 °
roof	10 mm @ 0 °
superstructure front	50 mm @ 78 °
sides	25 mm @ 75 °
rear	20 mm @ 90 °
top	10 mm @ 0 °
suspension front	50 mm @ 42 °
sides	25 mm @ 90 °
rear	20 mm @ -85 °

To be continued in part 6…

[tom]

Hi.

10) Medium Tanks part 6

f) Type 3 Medium Tank Chi-Nu:

The Type 1 47 mm tank gun was able to penetrate the US Medium M4 frontally on up to 450 m but only if the impact angle was around 90°. If the impact angle was lower the tank had to come closer making it an easy target. So a gun able to penetrate the M4 reliable on medium and longer ranges was necessary. Discontinuing the development of a long 57 mm tank and anti-tank gun in 1943 IJA had no better tank armament avaliable and the new tank designs wouldn´t be production ready before early 1945.

Therefore in mid 1943 IJA decided to upgun the Type 1 Chi-He as soon as possible as stopgap solution. First plans showed an upgraded version of the Type 2 Gun Tank Ho-I using the short-barreled Type 99 75 mm Tank Gun inside a better armoured turret. The AP-round of this gun was able to penetrate the side of a M4 on 950 m but the low muzzle velocity of 520 m/sec made aiming and accuracy problematic.

So the decision was made to use a modified version of the the Type 90 75 mm Field Gun similar to the main armament of the Type 1 Gun Tank Ho-Ni I. With its muzzle velocity of 680 m it was able to penetrate 65 mm armour on 1000 m with AP grenades. This was found acceptable. The gun became Type 3 75 mm Tank Gun. But recoil forces, recoil length and size of the ammunition made a new turret necessary. Prototype production started in May 1944 and in October tests started.

Type 3 Chi-Nu of IJA 4th Tank Division after surrender

The new turret was based on the turret of the Type 1 Chi-He. The chassis was not modified besides the turret ring which was enlarged from 1350 mm to 1700 mm. Flat armor plates were welded together in a hexagonal shape. A commander´s cupola with a two door hatch was placed offset to the right. Visor ports were mounted to the front, left, rear and right of the cupola. On the left side on the turret a large access hatch for gunner and loader was mounted. An AA-mount was placed in front of the hatch. Additional access hatches with visor slits and pistol ports were in each turret side. An ammunition hatch was in the rear turret but there was no MG in the turret. Due to the higher weight an electrical turret rotating system was used but it was still possible to turn it by hand.

Serial production of the tank designated “Type 3 Medium Tank Chi-Nu” was started in December 1944. Due to raw material shortages only between 150 and 166 vehicles were built, details were destroyed at surrender. The first six production vehicles were issued to IJA Tank School for crew training. From spring 1945 completed vehicles were used to equip two tank regiments and an independend tank brigade. None of these units reached operational status before surrender. But they would have been a nasty surprise for any US invasion force in late 1945/early 1946 as IJA managed to keep development and build-up secret. US Army inspectors were very surprised to find these tanks in the japanese tank force barracks.

Type 3 Medium Tank on the assembly line

After surrender one vehicle was sent to Aberdeen Proving Ground and scrapped after tests. A second vehicle was on display at US Army Akabane Arsenal in Tokyo and then handed over to Japanese Ground Self-Defence Force Ordnance School at Tsuchiura, Kanto Province. There it was restaurated and became an exhibit. It´s the only survivng Type 3 Chi-Nu, all other vehicles were destroyed.

Data:
As Type 1 Medium Tank Chi-He except

vehicles built: between 150 and 166
battle weight: 18,8 (metric) t
height: 2610 mm
maximum speed: 39 km/h on roads
Power/weight ratio: 12,8 hp/t
armament: 1 X Type 3 75 mm Tank Gun , 1 X Type 97 7,7 mm Tank MG
Ammunition capacitiy: 70 75 mm grenades, 3670 MG shots

armour	strength
turret front	50 mm @ 78 ° curved
sides	20 mm @ 80 °
rear	25 mm @ 90 °
roof	12 mm @ 0 °
superstructure front	50 mm @ 72 °
sides	25 mm @ 75 °
rear	20 mm @ 90 °
top	10 mm @ 0 °
suspension front	50 mm @ 42 °
sides	25 mm @ 90 °
rear	20 mm @ -85 °

Yours

tom!

[tom]

Hi.

11) Heavy Tanks part 1

a) Experimental Type 91 Heavy Tank:

After finishing the tests with the Experimental Tank No. 1 Army Technical Bureau decided to continue development of this design. Goal was to meet the original requirements and to implement new design ideas. Development started in March 1928 at Osaka Army Arsenal using the Experimental Tank No.1 as test vehicle.

First changes were made regarding the suspension. The general scheme was not changed but minor improvements were added. Two of the single roadwheels were removed and the remaining was slightly enlarged. The number of return rollers was increased by 2 (one forward and one in the rear) and they were placed in-line removing the track buckling. The suspension armor was simplified and the upper part was arranged sloped to improve mud removal. The weight was reduced significantly.

The engine was modified by using aluminium for several parts increasing the power while reducing weight. Power transmission was also improved. This lead to a maximum speed of 25 km/h. The exhaust pipe was placed inside the tank and the muffler was covered with a mesh wire netting against small rocks and debris.

First tests with modified suspension and the new main turret

The armor scheme of the superstructure wasn´t changed too much but vulnerable parts received a strength of 20 mm instead of 17 mm and more sloped parts were used. A new turret with a smaller commander´s cupola was developed with a MG port in the 7 o´clock position. Armament was changed to a Type 90 57 mm Tank Gun.

Continuous tests were made and every change was tested until it worked. Final weight was 16t as required for the Experimental Tank No. 1. In April 1930 the resulting vehicle was again showed to IJA High Command under the designation “Experimental Type 91 Heavy Tank” with mild steel armor plates. They were very pleased with the mobility but also demanded several changes:

• the main armament was found too weak for such a heavy vehicle
• the armor strength was found too weak for future fightings
• a stronger engine should be used

Development of the Type 91 Heavy tank was ceased in February 1932.

Data:
vehicles built: 1 as continuous development of the Experimental Tank No. 1
battle weight: 16 (metric) t
crew: 5 men
armor: up to 20 mm
length: 6300 mm
width: 2470 mm
height: 2570 mm
ground clearance: 400 mm
track width: 350 mm
trench crossing capability: 3000 mm
climbing capability: 43°
maximum vertical obstacle: 1000 mm
engine: modified BMW 6-cylinder in-line gasoline aircraft engine
power: 224 hp
maximum speed: 25 km/h on roads
transmission: 6 forward, 2 reverse
armament: 1 X Type 90 57 mm Tank Gun , 1 X Type Taisho 3 6,5 mm MG in the turret, 2 X Type Taisho 3 6,5 mm MG in separate turrets

b) Type 95 Heavy Tank:

The development of a successor of the Experimental Type 91 Heavy Tank started in December 1932 at Osaka Army Arsenal. The changes demanded lead to several reconstruction works. Additionally several new developments had to be started.

The suspension was changed completely to the system used on the Type 89 Medium Tank. It consisted of a see-saw type suspension using two pairs of 4 roadwheels connected with a bar and a single frontal roadwheel for increased climbing abilities. The driving sprocket was placed in the rear. A frontal idle wheel and four return rollers completed it. The external suspension armor sheme was changed to the Type 89 late production standard.

The superstructure was slightly remodeled raising it and increasing the length of the upper slope of the side armor. Maximum armor was now 35 mm. The forward turret was exchanged with a larger cylindrical turret housing a Type 94 37 mm Tank Gun to increase at-power of the vehicle. The main turret armament was changed to a Type 94 70 mm Tank Gun. The commander´s cupola was replaced by a flatter one with a two-door access hatch. Both remaining Type 3 MGs were replaced by Type 91 6,5 mm Tank MGs. The engine was remodeled, too.

The prototype was completed in September 1934. It had a combat weight of 26 t and the 290 hp engine only allowed a speed of 22 km/h. In addition the vehicle was now too large to be transported on narrow mountain railroads. Nevertheless 3 more vehicles with face-hardened armor plates instead of the mild steel plates used on the prototype were built at Osaka Army Arsenal prior to the official presentation in mid 1935. IJA officials were not pleased with this tank:

Type 95 Heavy Tank on display at Yasukuni Shrine

• the speed was found to low and the size too large
• use of a gasoline engine
• the armor strength was again considered too weak against contemporary tanks.
• in 1935 IJA tank doctrine does not need a heavy breakthrough tank as the main enemy was now considered China not the Soviet Union
• the military budget expected after 1935 did not allow the introduction of such an expensive vehicle

Therefore the decision was made to discontinue the development of a multi-turret tank design. One of the prototypes was handed over to Chiba Tank School for basic crew training, two were used for the development of heavy SPGs at Osaka Army Arsenal and the last became exhibit at Yasukuni Shrine in Tokyo. None survived the war.

Data
vehicles built: 1 as continuous development of the Experimental Type 91 Heavy Tank + 3
battle weight: 26 (metric) t
crew: 5 men
length: 6470 mm
width: 2700 mm
height: 2900 mm
ground clearance: 510 mm
track width: 480 mm
ground contact length: 4400 mm
trench crossing capability: 3000 mm
climbing capability: 43°
maximum vertical obstacle: 1100 mm
fording: 1100 mm
engine: remodeled BMW 6-cylinder in-line gasoline engine
power: 290 hp at 1600 rpm
maximum speed: 22 km/h on roads
fuel capacity: 400 l
lubricant oil capacity: 40 l
range: 110 km on roads
transmission: 6 forward, 2 reverse
Power/weight ratio: 11,15 hp/t
armament: 1 X Type 94 70 mm Tank Gun and 1 X Type 91 6,5 mm Tank MG in the main turret, 1 x Type 94 37 mm Tank Gun in the forward turret, 1 X Type 91 6,5 mm Tank MG in the rear turret
Ammunition capacity: 100 70 mm grenades, 250 37 mm grenades, 2940 MG shots

armour	strength
turret front	30 mm @ 80 °
sides	25 mm @ 90 °
rear	25 mm @ 90 °
roof	16 mm @ 0 °
superstructure front	35 mm
sides	30 mm
rear	25 mm
top	10 mm°
suspension front	35 mm
sides	unknown + 6 mm external
rear	25 mm

to be continued in part 2…

[tom]

Hi.

11) Heavy Tanks part 2

c) Experimental Superheavy Tank O-I:

no pic, sorry

The Nomonhan incident in 1939 showed that the japanese tanks were unable to cope with its tasks due to the superiority of the soviet tank models but also due to the use of massive artillery barrages used by the Red Army to stop enemy tank advances. So in late 1939 IJA high ranks decided to give the multiturret tank design a new chance. This time there should be no limitations towards weight and size of the vehicle. It only should be able to move at infantry speed in manchurian terrain and it should withstand direct hits of soviet contemporary 122 mm artillery gunfire. Transport should be done disassembled.

In early 1940 IJA 4th Technical Research Bureau and Mitsubishi were ordered to develop a prototype. Soon it became clear that at least 150 mm of armor would be necessary, resulting in a weight of more than 120 t. Therefore the existing tank technologies could not be used as they only allow a maximum weight of up to 30 t. So much basic development work had to be done first. As the project was rated top secret most development and production work was done in small, separated and even soundproofed barracks at 4 th Technical Research Bureau in Tokyo using the designation “Mi-To” (for Mitsubshi -Tokyo) to cover it. Even the engineers in charge with the design were not convinced that it would work.

The suspension consisted of eight pairs of 2-wheeled bogies, each bogie sprung by a massive vertical coil spring. The driving wheel was located at the rear. The armor was partly arranged sloped but the side armor was vertical. Basic armor strength was 75 mm on turrets, bow, rear and upper side armor, 35 mm on lower side armor and 50 mm on the roof to simplify handling. The final armor strength was achieved by bolting additional armor plates on near the frontline.

The tank was separated internally into three compartments by two bulkheads consisting of 20 mm armor plates with two doors each. There was the forward fighting compartment with the central drivers seat and the ammunition racks for the 47 mm turrets, the main fighting compartment below the central turret and the engine compartment in the rear half of the vehicle. The engines were placed side by side with a small maintenance corridor between them. The rear turret was placed above the gearbox making it a quite loud place.

Development was done in March 1941 and prototype production started on 14.04.1941. It was planned to build a less armored test vehicle within 3 months. Many non-secret parts were delivered by private companies. The rest was built at the barracks. But after just one month it became clear that the amount of raw materials provided by the army for the project would not be enough. Several rare metals were depleted and due to the war against China there was no chance to get further material soon. In addition there were problems with the cooling system. So the decision was made to postpone the production for 9 months until January 1942.

The hull was finished on 08.02.1942 for first mobility tests. The turrets should be built by Mitsubishi until May 1942 but only the bow and rear turrets were finished until then. Due to the lack of steel the main turret could not be finished with the upper armor plate missing. Nevertheless the superstructure was built and the smaller turrets implemented. With a basic armor strength of 75 mm and 35 mm turret roofs the total weight was already 96 t. The necessary remaining raw materials were not available before 1943 and it was impossible to continue without them. So the development was again postponed. Only mobility and basic handling tests were done with more or less success. Until summer 1943 the final tests of the prototype were done and the project officially demonstrated to IJA High Command. At this time the vehicle received the official short designation “O-I” (O = short for superheavy, I = first design). The tank impressed the spectators and therefore an immediate start of field trials was ordered. These should be done at Sagami Army Arsenal. So the prototype was disassembled within one night and the parts were sent to the arsenal during several nights by truck. On 01.08.1943 assembly was finished and tests started the same day. The vehicle had no problems with hard and semi-hard terrain but after driving on muddy terrain it sank in up to the coil springs, damaging the suspension. It was recovered and several tests were finished on concrete. The damage to the suspension had to be repaired as it inflicted damage to the concrete. So further tests had to be postponed. So the tank was disassembled from 03. to 08.08.1943 and sent back to 4 th Technical Research Bureau.

The further fate is unknown but the project wasn´t continued. It´s possible that it was shipped to Manchuria for further trials but there is no evidence of this. Soviet sources mention a motorised wooden mock-up found in Manchuria.

Even if the tank would have reached operational status there are several questions regarding a use. Main problem was the raw material situation making it almost impossible to produce such massive constructions. In addition vehicles like these were prime (and easy) artillery and aircraft targets making a successful use very unlikely. And the contemporary development of AT-weapons did not stop making even 150 mm of armor not impenetrable in 1944.

Data:
vehicles built: 1
battle weight: 150 (metric) t
crew: 6 men
length: 10100 mm
width: 4833 mm
height: 3600 mm
track width: 800 mm
engine: Kawasaki Type 98 V12 gasoline X 2
power: 550 hp X 2
maximum speed: 29,4 km/h on roads
transmisson: 6 forward, 2 reverse
Power/weight ratio: 7,3 hp/t
armament: 1 X Type 96 15 cm howitzer, 1 X Type 1 47 mm Tank Gun in each bow turret, 1 X Type 97 7,7 mm MG in the rear turret
Ammunition capacitiy: ca. 100 150 mm grenades, ca. 200 47 mm grenades, ca. 4000 MG shots

armor	strength
turret front	150 mm @ 90 °
sides	150 mm @ 90 °
rear	150 mm @ 90 °
roof	50 mm @ 0 °
superstructure front	150 mm @ 71,4 °
sides	105 mm @ 90
rear	150 mm @ 47 °
top	50 mm° @0 °
suspension front	150 mm @ 33,7 °
sides	70 mm @ 90 °
rear	150 mm @72 °, lower part @ -57 °

to be continued in part 3…

[tom]

Hi.

11) Heavy Tanks part 3

The following tanks are added here as they fit into the original IJA definition for a heavy tank.

d) Type 4 Tank Chi-To part 1:

In mid 1942 IJA had to realise that they had massively fallen back in tank technology and that it would be suicide to continue the contemporary general outline for tank usage and development. Especially the new soviet tanks T-34 and KV-1 were far superiour to anything they even thought of but the US Medium M3 and the british cruiser and infantry tanks were also more or less outclassing everything in the own arsenals. Therefore a large development program was started including new tanks, gun tanks and gun carriers able to fight contemporary and future enemy tanks.

One of these developments was a tank to replace all the medium tanks as soon as possible. Requirements were among others:

• maximum weight 20-22 t
• armament consisting of the Type 1 47 mm Tank Gun and two MGs, but the use of the 57 mm tank gun under development at this time should be possible
• crew consisting of driver, bow gunner/wireless operator, commander, loader and gunner
• maximum armor strength 50 mm
• suspension using already standardised elements of the predecessors
• road speed 40 km/h
• no size limitations regarding railway transport

Army Technical Bureau started development in cooperation with Mitsubishi in September 1942. It was clear that the 57 mm tank gun needed a larger turret than the 47 mm gun. This lead to the necessity to use a stronger engine which would be larger than the Type 100 engine used for the Type 1 Chi-He which was under development at the same time. So the suspension had to be lengthened. Therefore the single roadwheels of the Chi-Ha suspension were removed and the center pairs were mounted at the front. A single roadwheel and a third pair of roadwheels connected with bell cranks to a second large horizontal coil spring were added in the rear.

Type 4 Tank after surrender with MGs removed

The chassis armour was similar to the one used on the Chi-He but with a longer engine compartment. There was no access hatch above the bow gunner. The rear armour consisted of a sloped upper part, a vertical center part and a negatively angled lower part. A large two-door engine access hatch was placed above the engine compartment ventilation and combustion air intakes covered with armor plates were mounted in the center of the access doors. The exhaust pipes lead directly to wire netting covered mufflers on each rear mudguard.

The turret was similar to the one used on the Type 3 Chi-Nu which was designed one year later but casted. This caused massive problems as casting wasn´t often used in Japan. So the technology was not very sophisticated. There were many quality problems but these were finally solved. It had a hexagonal shape with smaller sides to the front and longer rear sides. The turret rear overhang was shorter. There was one access hatch in the rear for ammunition supply and a large two-door hatch above the gunner´s position on the (in driving direction) left turret top but none in the turret sides. A cylindrical commanders cupola with observation ports and a two-door hatch was placed on the right side. A standard AA-mount for a tank MG was positioned in front of the gunner´s hatch. The turret was placed centered on the fighting compartment. The gun mantlet was also similar to the later Chi-Nu and there was also no rear turret MG. But it was planned to add a coaxial MG.

The prototype development was done until June 1943. At this time the 47 mm tank gun was rated to be too weak against future tanks as faced by german forces in Africa or the Soviet Union. So in July 1943 after examining a Panzerkampfwagen V Panther Ausführung A and a Panzerkampfwagen VI Tiger Ausführung E (these were donated to Wehrmacht after finishing the tests because there was no chance to ship them to Japan) bought in Germany IJA changed the requirements to:

• use of the 57 mm main gun
• 75 mm maximum armour
• maximum weight 25 t

Therefore the design had to be improved regarding armour and suspension which was done until late 1943. A prototype of the tank was produced at Mitsubishi´s Maruko factory until May 1944. The main gun was problematic as the basic development made for a anti-tank gun was ceased in late 1942 due to a lack of power and a too high weight. During a test of the tank gun prototype under perfect conditions in March 1944 only a penetration of 60 mm at 90° on 1000 m was achieved which was rated far too low against future tanks. Therefore the decision was made to discontinue this development and to change to a 75 mm main armament in April 1944.

vehicle ready to be shipped to the USA

First designs used the turret of the type 3 Medium Tank with its Type 3 75 mm Tank Gun but this gun was also not really suitable against heavy enemy tanks. So in July 1944 the decision was made to develop a tank gun based on the newly introduced Type 4 75 mm AA-Gun. But first trials were done in August 1944 using a Chi-Nu turret. The trials with a dummy of the gun mounted inside the Chi-Nu turret showed problems regarding handling due to narrowness. So the decision was made to develop a new larger turret, too.

This turret also had a hexagonal basic shape but the side armour was made out of a single curved armour plate. The turret rear was casted, all other armour plates were made of rolled homogenous steel. A two-door access hatch and a standard AA-mount were placed above the gunner´s seat on the left side of the turret top. The commander entered the tank through a cylindrical commanders cupola with a two-door access hatch. A periscope was mounted in front of the cupola. A standard MG port was placed on the rear right of the turret side armour to be operated by the loader. The coaxial MG had been abandoned.

The turret was placed offset to the right on the fighting compartment. Due to its larger size the driver and bow gunner position had to be shifted forward a little bit which resulted in a reduction of the slope of the upper frontal armour. This also allowed the use of an access hatch above the bow gunner again. To reach the expected necessary engine power Mitsubishi developed a new Diesel engine based on a small ship engine.

In February 1945 the turret was finished and prototype tests of the vehicle now designated “Type 4 Tank Chi-To” started in March. The gun development was delayed until late March 1945. Due to raw material shortages only two tank guns and five pre-production vehicles could be built until June 1945. At this time final operational tests started at IJA Chiba Tank School which lasted until surrender. First tests showed a very good mobility and a potent armament. Therefore IJA decided to scrape together raw materials for 200 vehicles by ceasing most other tank and also many other weapon productions. Mitsubishi was ordered to start production in September 1945, delivery should be done until December 1945 which was nearly impossible with the increasing damages due to US strategical bombings. There were plans to use fully casted turrets but the producing company Japan Steel announced that they wouldn´t be able to deliver so many turrets in such a short time. Another idea was to use parts of the Chi-Nu turret production for completely welded turrets but this was rejected as it would have lead to a production decrease of this tank type. So the mixed prototype turret type should be used. Another simplification of the production model should have been the removing of the air intake armour protection.

rear view, note the wrong US designation.

The development of this tank was also kept in secret making it a big surprise for the US Army, too. One of the completed vehicles should be sent to Aberdeen Proving Ground but there is no record of a test there. There are rumors that the prototype was either lost during transport or that it was mixed up with the Type 5 Chi-Ri prototype (see US designation on the last picture) and never shipped. Several Type 4 Tanks were sunk together with other tanks in Lake Hamana, Shizuoka prefecture, after surrender. In 2003/04 there was a campaign to rise at least one of the tanks by japanese military enthusiasts but with no success. There are trials to start a new campaign at the moment.

to be continued in part 4…

[tom]

Hi.

11) Heavy Tanks part 4

d) Type 4 Tank Chi-To part 2:

Data:
vehicles built: 6 (4 without main armament)
battle weight: 24 (metric) t empty, 30 t fully loaded
crew: 5 men
length: 6340 mm
width: 2860 mm
height: 2670 mm
ground clearance: 420 mm
track width: 450 mm
trench crossing capability: 2700 mm
climbing capability: 35°
fording: 1200 mm
engine: Mitsubishi Type 4 V-type 37.700 cm³ 12-cylinder Diesel engine
power: 412 hp at 1800 rpm
maximum speed: 45 km/h on roads, 28 km/h cross country
range: 250 km on roads
transmission: 4 forward, 1 reverse
Power/weight ratio: 13,8 hp/t
armament: 1 X Type 5 75 mm Tank Gun , 2 X Type 97 7,7 mm Tank MG
Ammunition capacity: 65 75 mm grenades, 5400 MG shots

armor	strength
turret front	75 mm @ 75 °
sides	50 mm @ 75 °
rear	50 mm @ 75 °
roof	20 mm @ 0 °
superstructure front	75 mm @ 75 °
sides	35 mm @ 65 @
rear	50 mm @ 90 °, upper part @ 40 °
top	16 mm° @ 0 °
suspension front	75 mm @ -20 °
sides	25mm @ 90 °
rear	50 mm @ -40 °

e) Experimental Type 5 Tank Chi-Ri:

With the decision to equip the Type 4 Tank at least with the 57 mm tank gun in July 1943 IJA also ordered the development of a larger version. Requirements were among others:

• use of a 75 mm tank gun
• 75 mm maximum armor, 50 mm upper side armor
• maximum weight 35 t
• operational range 200 km
• use of a 105 m tank gun should be prepared
• up to 130 mm maximum armor should be possible
• semi-automatic loading mechanism to increase fire cadence
• maximum use of already standardised suspension parts

Design started on August 19th, 1943. Until September 23rd, 1943, a wooden mock-up was finished as basis for further developments. It was planned to develop the tank within one year and to start serial production within two years. Several design features were built following the results of the examination of the Panther and Tiger I tank bought and examined in Germany from Mai 1943. Other details were following domestic solutions.

The suspension of the Type 4 Tank under development was enlarged by an eighth roadwheel paired with the single roadwheel of the Chi-To. A stronger driving sprocket was designed and more massive bell cranks, thicker rubber bands plus heavier coil springs were used. The highest possible weight was calculated around 55 t which wouldn´t be enough for all required upgrade possibilities. But this was accepted to get the tank into production.

The lower bow armor was similar to the Chi-To, the superstructure armor scheme was similar the Tiger I but with a slight slope. Both edges of the upper frontal armor were arranged diagonal. Instead of the standard MG mount a Type 1 37 mm Tank Gun with a coaxial MG was mounted in the bow. This arrangement should increase the fighting power as the 37 mm gun was able to take out MGs and infantry in field fortifications as well as soft skinned and thinly armoured fighting vehicles. So the main gun could fire on harder targets and in addition the tank was still able to fire during reload.

The rear armor consisted of a vertical plate with a negatively sloped lower part. The rear vertical edges were also arranged vertically sloped. A multi-door engine access hatch with ventilation and cooling air intakes with grilles along the center line covered the engine compartment. The exhaust pipes were exiting the vehicle in the rear leading to two mufflers placed on the upper rear armor.

The turret was massive and large enough to house the Type 5 105 mm gun, a semi-automatic loading mechanism and if necessary a second loader. The basic shape was hexagonal with a lengthened rear part. For the first time in Japan the turret crew stood or sat in a basket rotating with the turret. In each forward side armour plate a visor slit with a pistol port below was placed. A standard MG mount was mounted in the forward part of the (in driving direction) left rear side armor operated by the gunner. In the center of each rear side armor a small access hatch for ammunition supply with a visor slit was added. Above the gunner´s seat was an access hatch in the left top armor. Behind this hatch a periscope for the commander was placed. Behind it a cylindrical commanders cupola with a two-door access hatch was mounted. The top armor armour was arranged slightly angled with a kink at the center of the cupola. An antenna base was mounted on each side of the turret at the kink. The loader/s was/were placed on the right side of the turret. A simple gun stabilisation and an electrical turret rotating mechanism were planned.

For the expected weight a stronger engine than for the Type 4 Chi-To was necessary. Mitsubishi saw no chance to develop an air-cooled engine with more than 500 hp in time. So they developed a liquid-cooled, supercharged 550 hp Diesel engine from the Kawasaki Type 98 C9- IIb V-type 12 cylinder liquid-cooled 800 hp aircraft engine, a license-built version of the BMW VI (aka BMW 106) aircraft engine. The tank was operated with a driving wheel over hydraulical elements.

rear view, exhaust pipes are missing

All armor plates were still face-hardened but due the thickness the producing company had problems to reach the expected quality. Therefore the prototype had to be built with several steel plates not reaching the projected hardness. Until surrender only the armor body and the turret were finished. The engine wasn´t mounted and also no gun. The semi-autoloader had already been abandoned in mid 1945 due to development problems. Many parts of the interiour including, ammunition storage, turret rotating mechanism and stabilisation weren´t finished, too.

After surrender the US Army observers were very surprised to see such a heavy vehicle under construction. The prototype should be shipped to Aberdeen Proving Ground but there is no known test report. So the fate is unknown.

Several western authors assert that it was planned to use a 88 mm main gun as armament but there was no evidence found so far among primary sources. It´s only sure that the prototype should be tested with a Type 5 75 mm Tank Gun. Everything else is just an assumption.

Data
vehicles built: 1, not finished
weight: 37 (metric) t empty, 46 t fully loaded
crew: 5 men
length: 8467 mm
width: 3050 mm
height: 3100 mm
ground clearance: 400 mm
track width: 600 mm
ground preasure: 0,6 kg/cm²
trench crossing capability: 3000 mm
climbing capability: 30°
fording: 1200 mm
engine: modified Kawasaki Type 98 C9 IIb liquid-cooled 12-cylinder Diesel engine with supercharger
power: 550 hp at 1500 rpm
maximum speed: 42 km/h on roads
range: 180 km on roads
Power/weight ratio: 14,9 hp/t
armament: 1 X Type 5 75 mm Tank Gun and 1 X Type 97 7,7 mm Tank MG in the turret, 1 X Type 1 37 mm Tank Gun and 1 X Type 97 7,7 mm Tank MG coaxial in the bow, 1 X Type 100 8 mm Submachine Gun for close defence
Ammunition capacity: 100 75 mm grenades, 102 37 mm grenades, 5400 MG shots

armor	strength
turret front	75 mm @ 72 °
sides	50 mm @ 74 °
rear	50 mm @ 90 °
roof	20 mm @ 0 °
superstructure front	75 mm @ 72 °
sides	35 mm @ 74 °@
rear	50 mm @ 90 °
top	12 mm° @ 0 °
suspension front	75 mm @ -20 °
sides	35 mm @ 90 °
rear	50 mm @ -10 °

Yours

tom!

[tom]

Hi.

12) Gun Tanks part 1

During the late 1930th IJA 1st Army Technical Bureau in charge of artillery equipment made several suggestions to mobilise several artillery pieces using medium and heavy tank chassis. Most remained projects but at least two different suggestions were built as prototypes. After 1941 all close support, anti-tank and self-propelled artillery vehicles used by tank units were designated “Gun Tanks”. They were all build in small numbers only. Data on the early and later vehicles are quite rare.

It was planned to equip each tank regiment with a 5th company of 10 gun tanks after 1943 (1 gun tank and 2 light tanks in the command section, 3 platoons with 3 gun tanks each). But this never happened due to the low production priority. In addition a lot of different gun tanks were developed and produced making it hard to equip a company with a single type. Many tank regiments received medium tanks instead of gun tanks for their 5th company

a) early projects:

experimental self propelled gun, second suggestion

In 1937/38 IJA Technical Bureau suggested the use of tank chassis to motorise heavy artillery pieces. In 1938 two of the rejected Type 95 Heavy Tanks were used to demonstrate the possibilities of these suggestions. The first version used a Type 92 10 cm cannon which was mounted in an enclosed fighting compartment on the rear of the remodeled vehicle. To do this the engine compartment was shifted to the center. This vehicle is known as “Jiro” or “Jiro-Sha” in literature, short for “Jidosoho Ro-Go” = “Motorised Gun, 1st Version”. No picture was found so far.

The second suggestion was to simply mount a gun instead of the bow turret and to remove the main turret and parts of the fighting compartment to get space for the crew. Armament ist unknown but it seems to be a 12 cm or 15 cm gun in a pivot mount The designation of this vehicle ist unknown but in western literature and on the web it is known as “Hiro” or “Hiro-Sha” but this seems to be fictional.

The fate of the prototypes is unknown but the second suggested vehicle was found at Tateyama barracks after surrender.

no further data.

b) Type 2 Gun Tank Ho-I:

first prototype during tests

During the innitial stages of the China Incident IJA suffered heavy losses during the Shanghai street fightings. The 57 mm guns of the Type 89 tanks were useful but could not destroy heavy fortified positions fast. So after the decison was made to introduce the Type 97 Medium Tank Chi-Ha ideas came up to develop a close support version with a larger gun similar to the british CS-tanks. The main gun should be based on the obsolete Type Meiji 41 75 mm Mountain Gun which was used as infantry gun since 1935. Design started in July 1937 but with low priority. Main task was to develop a new turret as the Chi-Ha turret was too narrow to use a bigger gun

The prototype wasn´t finished until late 1940. The final turret design was an improved version of the new turret for the Chi-Ha KAI with welded, flat armor plates. The basic shape was hexagonal with a lengthened rear part. Frontal armor strength was 25 mm. A small access hatch with visor slit was mounted each rear side armor. A large ammunition suply hatch was mounted in the rear. Loader and commander were placed on the (in driving direction) left side of the turret. A cylindrical commanders cupola with a two-door access hatch on the left and a one-door access hatch on the right above the gunner´s position allowed entering the vehicle. A periscope was monted in front of the cupola. To reduce height the upper parts of the turret were arranged sloped. Besides an increase of the turret ring diameter the chassis of the Chi-Ha wasn´t changed.

Tests with this vehicle started in spring 1941. In September operational tests were done at Chiba tank school. They showed good performance agains stationary targets but due to the quite low muzzle velocity it was very problematic to hit moving targets. In addition the armour piercing capacity of 40 mm at 100 m/90° was rated too weak which lead to the development of a HEAT grenade.

In 1942 the turret was simplified by Hitachi. The upper slope was removed and the sides heightened. Now the upper armor had a kink in the middle. The side armor plate connections were now strengthened by rivets. The frontal armor strength was increased from 25 mm to 50 mm. A flatter commander´s cupola was mount and an AA-mount was added in front of the gunner´s hatch. The recoil mechanism armor was remodelled and received a better bullet deflecting shape. In addition the chassis of the Type 1 Chi-He was used. The better armor protection was appreciated.

Serial production vehicle

Preparations for serial production did not start before 1943 due to a very low priority. At this time there were ideas to upgun this vehicle with the 57 mm tank gun under development at this time making it an upgunned Chi-He. After finishing the development of the HEAT ammunition the decision was made to introduce this tank under the designation “Type 2 Gun Tank Ho-I”. Production did not start before 1944 and only 30 vehicles were finished by Mitsubishi. Then the production was changed to the more powerful Type 3 Medium Tank. The vehicles produced were issued to the regiments of IJA 4th Tank Division stationed in Japan for homeland defence. All were destroyed after surrender with one being sent to Aberdeen Proving Ground first.

The Type 2 Gun Tank was a good step into the right direction, especially after introducing the Type 1 47 mm tank gun with its limited HE-power. But it was inferiour to the Type 1 Gun Tanks Ho-Ni I and II and so keeping the raw material shortages in mind the production should not have been started.

The first prototype is sometimes wrongly designated “Type 1 Gun Tank Ho-I” in western literature.

Data
as Type 1 Medium Tank Chi-He except

vehicles built: 30
battle weight: 15,4 (metric) t empty, 16,7 t fully loaded
crew: 5 men
height: 2580 mm
armament: 1 X Type 99 75 mm Tank Gun, 1 X Type 97 7,7 mm Tank MG
Ammunition capacitiy: 63 75 mm grenades, 2120 MG shots

armour	strength
turret front	50 mm @ 80 °
sides	35 mm @ 75 °
rear	20 mm @ 78 °
roof	10 mm @ 0 °
superstructure front	50 mm @ 78 °
sides	25 mm @ 75 °
rear	20 mm @ 90 °
top	16 mm @ 0 °
suspension front	50 mm @ 42 °
sides	25 mm @ 90 °
rear	20 mm @ -85 °

To be continued in part 2…

[tom]

Hi.

12) Gun Tanks part 2

c) Type 1 Gun Tank Ho-Ni I:

The second idea for a close support vehicle was to mount the very good Type 90 75 mm Field Gun on the Type 97 Chi-Ha. The design started with low priority in December 1939 at 1st Army Research Institute (in charge of developing artillery guns and equipment) because it was rated as self-propelled gun not gun tank at this time. The prototype based on the Type 97 Medium Tank Chi-Ha was built by Hitachi. It was finished in May 1941.

The turret and the top armor of the fighting compartment were removed. Instead a large, slightly sloped armor shield was mounted directly behind the upper frontal armor. Small vertical armor plates with rectangular upper part and trapezoid lower part on the sides and an armor plate with the same width as the upper side plate on top completed crew protection. Visor hatches were mounted in each sides armor plates. A Type 93 0,75 m rangefinder was mounted on the (in driving direction) right side of the top armor plate. It was operated by the commander. The gunner stood on the left side of the gun protected from ejected shell cases by a simple deflector. Therefore the bow gunner´s seat was removed and the MG port was replaced by a 16 mm armor plate. Ammunition racks were also stored there. More ammunition was placed on each side of the fighting compartment and below the floor plates next to the driving shaft. Two loaders and the driver completed the crew. A standard Type 90 Field Gun with parts of the recoil mechanism was mounted in a special lafette with two coil springs below the rear of the cradle to lower recoil forces. This allowed using the gun without its muzzle break. Instead a 70 mm thick muzzle ring with an outer diameter of 160 mm was added to reduce attrition. An armor plate mounted on the gun closed the necessary opening in gun shield. The elevation was limited to 20° due to the limited space below the gun reducing the maximum range. This was found acceptable due to the massive increase in mobility. Maximum traverse was 25° to each side.

First vehicle tests started in June, operational tests were done at Army Field Artillery School from October. Until late 1941 all tests were done and the decision was made to introduce this vehicle not as gun carrier for artillery unit but as gun tank for tank units. The further development before serial production was made by 4th Army Research Institute (in charge of develop tanks and equipment). The changes included a simple notch and bead sight for direct fire against enemy targets (mainly tanks) and several simplifications. The rangefinder was removed. To increase protection the side armour was enlarged, the sides of the gun shield were bend backwards and the frontal armour strength was increased to 50,8 mm. The visor hatches were now placed on the upper part of the side armour and a third hatch was added to the left forward side armour. The upper armour was remodeled and shortened. A V-shape cut was added on the gunner´s side for a different indirect fire sight. Later a standard AA-mount was added on the left of the cut in the top armour. The changes were done until early 1943 but due to the lack of raw materials and capacities at Hitachi serial production did not start before November 1943. At least 124 Ho-Ni I were produced until surrender.

prototype with 0,75 m rangefinder

The produced vehicles were issued to tank regiments and so called Armored Mobile Artillery Regiments and Battalions. Each mobile artillery company consisted of two observation tanks and 4 platoons with one gun tank and one armoured transport vehicle each (following the contemporary artillery buildup). Two companies were in each battalion and two battalions in each regiment. But most tanks were used in gun tank companies (for OOB see introduction of this post). Ho- Ni I and Ho-Ni II were used side by side.

First operational use was with the IJA 14th Tank Regiment during the 1944/45 retreats in Burma but with only few vehicles. Tank regiments in China used several Ho-Ni I , too. A transport of 14 Ho-Ni I and II for 10th Tank Regiment, 2nd Tank Division, to Luzon was attacked by US aircraft and only 2 vehicles made it to the Philippines. The 2nd Armored Mobile Artillery Regiment´s transport convoy was also attacked en route to Luzon and lost half of its 8 Ho-Ni I. Both units were later wiped out during the final stages of the US Luzon campaign but two Ho-Ni I were captured damaged. Both were sent to Aberdeen Proving Ground, one is on display there today. It´s the only known surviving vehicle.

rear view of the fighting compartment, note the unit insignia of the 2nd Armored Mobile Artillery Regiment (Hinomaru with white circle)

The Type 1 Gun Tank Ho-Ni I was a good SPG with a small but powerful gun. For its caliber it had a good HE power and (compared to the other IJA tanks before introduction of the Type 3 Chi-Nu) the AT-power was superiour to anything else available. For penetration data see Type 3 75 mm Tank Gun. It was intended to support attacking units with close-range indirect artillery fire but was mainly used for direct fire. The missing special direct fire optics made it very hard to hit targets with the first shot and it was almost impossible to hit moving targets. In addition the relatively weak armor made it vulnerable if facing enemy at-fire. Nevertheless it provided useful heavy fire support.

Data
as Type 97 Medium Tank Chi-Ha except:

vehicles built: ca. 124
battle weight: 14,7 (metric) t
crew: 5 men
length: 5900 mm
height: 2290 mm
maximum speed: 40 km/h on roads
armament: 1 X Type 90 75 mm Field Gun in a special mount,
Ammunition capacity: 24 75 mm grenades

armour	strength
gun shield front	50,8 mm @ 75 °
sides	12 mm @ 90 °
rear	none°
roof	10 mm @ 0 °
superstructure front	25 mm @ 78 °
sides	25 mm @ 75 °
rear	20 mm @ 25 °
top	10 mm @ 10 °
suspension front	25 mm @ 42 °
sides	25 mm @ 90 °
rear	20 mm curved

d) Type 1 Gun Tank Ho-Ni II part 1:

During the final stages of the development of the Ho-Ni I the idea came up to use the larger caliber Type 91 105 mm Howitzer with its shorter barrel on such a vehicle, too. The first design studies were made in March 1941. A prototype was built by Hitachi until June 1942.

The basic vehicle was the same as the Ho-Ni I. The main gun was replaced by a howitzer barrel making only minor changes to the mount necessary. Only disadvantages were a minimum range of 485 m due to recoil mechanism limitations and a maximum range of 10800 m (at 22° elevation) due to the limited space inside the vehicle. These were accepted. As the vehicle should only provide indirect fire the thickness of the armor shield was reduced to 25 mm.

Functional tests at Osaka Army Arsenal and operational tests at Army Field Artillery School followed. During winter 1942/43 climatic tests in Manchuria showed problems with the gun mount brackets if firing with maximum traverse of 25° at -27°C. Therefore the maximum traverse was limited to 10° to each side. The ammunition load of 16 grenades and charges was criticised and so additional ammunition racks for 4 grenades and charges were mounted on the engine room behind the fighting compartment. To maintain the engine the rack had to be removed.

In mid 1943 IJA decided to use the vehicle as gun tank and not as self-propelled gun, too. Direct fire should be possible now and so the armor thickness of the gun shield was increased to 41 mm and a simple notch and bead sight was added. These changes were done fast and so serial production could start in November 1943 at Hitachi parallel to the Ho-Ni I. The total production numbers are unknown but did not exceed 55 vehicles.

The produced vehicles were mainly issued to the Armored Mobile Artillery Regiments of the tank divisions. 8 Ho-Ni II were sent to Luzon with the 2nd Armored Mobile Artillery Regiment but only 6 survived the US attacks on the convoy. The unit was wiped out during the final stages of the US Luzon campaign in 1945. All other production vehicles were issued to homeland defense units. There is no known surviving vehicle.

rear view, note the different breech and the additional ammunition racks on the engine compartment

The vehicle had an at-power comparable to the Ho-Ni I (83 mm on 100 m/90°, 70 mm on 1000 m/90° with AP ammunition, 120 mm with HEAT ammunition) but the HE-power was superior. On the other hand the lower muzzle velocity and lower firing speed made it even harder to hit moving targets. So direct fire wasn´t really a good option. But it was a good SPG.

To be continued in part 3…