japanese tanks and armored vehicles

11) Heavy Tanks

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 aluminum 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 main 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

armor strength
turret front
30 mm @ 80 °[/td]
sides
25 mm @ 90 °
rear
25 mm @ 90 °
top
16 mm @ 0 °
superstructure fron
35 mm
sides
30 mm
rear
25 mm
top10 mm°
suspension front
35 mm
sides
unknown + 6 mm external
rear
25 mm


Yours

tom!

 

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. Therefore 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
transmission: 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 capacity: 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 °
top
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 °


Yours

tom!

 

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


d) Type 4 Tank Chi-To:



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 inmid 1943 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.

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

Yours

tom!

 

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 armor 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 °
top
20 mm @ 0 °s
uperstructure 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!

 

12) Gun Tanks

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.



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 capacity: 63 75 mm grenades, 2120 MG shots

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

Yours

tom!

 

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 units 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 superior 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

armor strength
gun shield front
50,8 mm @ 75 °
sides
12 mm @ 90 °
rear
none
top
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
5 mm @ 90 °
rear
20 mm curved

Yours

tom!

 

d) Type 1 Gun Tank Ho-Ni II:



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.

Data

as Type 97 Medium Tank Chi-Ha Except:
vehicles built: ca. 55
battle weight: 16,3 (metric) t
crew: 5 men
height: 2290 mm, 2390 mm at maximum elevation due to the protrusion of the armour plate on the gun Barrel (see first picture)
maximum speed: 38 km/h on roads
armament: 1 X Type 91 105 mm Howitzer in a special mount,
ammunition capacity: 20 105 mm grenades

armor strength
gun shield front

41 mm at 75°​

side

12 mm at 90°​

rear
none
top

10 mm at 0°​

superstructure front

25 mm at 78°
side
25 mm at 75°​

rear

20 mm at 25°​

roof

10 mm at 10°​

suspension front

25 mm at 42°
side
25 mm at 90°​

rear

20 mm curved​

e) Type 3 Gun Tank Ho-Ni III:



During the operational tests of the Ho-Ni I the open fighting compartment and the missing direct fire optics were problematic. But these problems were accepted to get the vehicle ready for serial production. In 1943 a trial was started to remodel the Ho-Ni I to solve these problems.

The armour shields were replaced by a heptagonal construction consisting of a frontal plate, two forward side armour plates, two side armour plates (all arranged sloped) and two vertical rear armor plates. Armor strength did not exceed 25 mm, just enough against splinters and infantry AP ammunition. Visor slits with pistol ports below them were placed on both sides of the gun and in each forward side plate. A small access hatch opening upwards with a pistol port below it was in each side plate. A large access door with a small access hatch in each of the rear armor plates in combination with a pentagonal hatch in the rear top armor allowed entering the fighting compartment. A hatch with a rectangular and a crab shear type door above the gunner´s position allowed using an indirect fire sight. A simple optical sight for direct fire was also added. Another hatch was placed above the commander´s position. An additional small gun shield to protect the gun slit was placed outside of the vehicle.

Prototype tests started in early 1944 and were finished successfully fast. So IJA decided to introduce this vehicle, too. Later that year after finishing the development of the Type 3 75 mm tank gun it was decided to use this gun instead of the Type 90 Field Gun which was badly needed as artillery gun. Changes were done fast and serial production started in summer 1944. Total production numbers are not known but at least 38 vehicles leaved the assembly lines. They were issued to the gun tank companies of the tank regiments of 4th Tank Division for homeland defense. All were destroyed after surrender.


rear views with opened and closed rear doors

Besides the indirect fire sight the Ho-Ni III was more an assault gun comparable to a contemporary StuG III than a SPG. HE-power was limited but the armor penetration was enough to penetrate the US Medium M4. Only the height and the armor thickness were criticised. It replaced the Ho-Ni I in several gun tank companies. US Army did not know about its existence before surrender.

Data:

as Type 97 Medium Tank Chi-Ha except
vehicles built: ca. 38
battle weight: 17 (metric) t
crew: 5 men
length: 5900 mm
height: 2370 mm
maximum speed: 38 km/h on roads
power/weight ratio: 10 hp/t
armament: 1 X Type 3 75 mm Tank Gun
ammunition capacity: unknown

armor strength
fighting compartment front
25 mm @ 75 °
sides
12 mm @ 75 °
rear
25 mm @ 90 °
top
16 mm @ 0 °
superstructure front
25 mm @ 82 °
sides
25 mm @ 75 °
rear
20 mm @ 25 °
top
10 mm @ 10 °
suspension front
25 mm @ 42 °
sides
25 mm @ 90 °
rear
0 mm curved

Yours

tom!

 

f) Type 4 Gun Tank Ho-Ro:



In 1944 IJA decided to to use everything available to increase the firepower of their armored units. One of the resulting projects was a gun tank using the obsolete Type Meiji 38 15 cm Howitzer as main armament. The basic shape was similar to the Type 1 Gun Tank Ho-Ni I but the crew protection was completely remodelled and simplified. The upper frontal armor was removed and a single 25 mm thick armor plate also serving as gun shield was mounted with a slope instead. On the (in driving direction) left of the gun a long small hatch for a simple direct fire optic was mounted. On the right a driver´s optic in the lower part and a hatch for the commander were placed. A second visor hatch for the commander was mounted on the forward side armor. The side of the crew protecting armor had a step following the upper superstructure of the tank. The top armor was as wide as the side armor and a hatch was mounted above the commander´s position. The armor was welded, the visible rivets are used for mounting interiour elements only.

The gun including the upper lafette was mounted in a trestle riveted to the gun shield. Due to the stress of the recoil forces on the structure the traverse was limited to 3° to each side. Elevation was -10° to 20 ° reducing the maximum range from 5900 to 4850 m. This was accepted in exchange for a massively increased mobility (horse-mounted the gun had to be transported in 2 loads). The heavier ammunition (35,9 kg instead of 6,56 kg for the Type 90 75 mm Field gun and 15,8 kg for the Type 91 105 mm Howitzer) made a third loader necessary. The ammuniton capacity of 16 genades and charges of the fighting compartment was increased by a large ammunition rack on the engine compartment for 12 grenades and charges.

Development and tests started in July 1944 and were finished quickly. Serial production started in late 1944 at Mitsubishi´s Maruko factory. Total production numbers are unknown but estimated between 12 and 25 vehicles only. On August 12th, 1944, the first unit (Sumi Independent Self-Propelled Gun Company) started training at Army Field Artillery School without vehicles to archieve operational status as soon as possible. This unit received four vehicles before it was sent to Luzon on December 22nd 1944. The convoy was attacked by US aircraft who destroyed two Ho-Ro on board Aoba Maru. The rest of the unit was wiped out at the end of the US Luzon campaign in 1945. One vehicle was heavily damaged by US M2 .50 MGs using AP ammunition, the other one was captured. Combat records of the japanese unit mention at least seven destroyed and several damaged US tanks during the whole campaign, at least one was destroyed at a range of just 100 m. The other production vehicles were issued to the divisional artillery of the 4th Tank Division for homeland defence.

The vehicle captured on Luzon was sent to Aberdeen Proving Ground for examination in mid 1945. It is still existing at the National Museum of the Marine Corps near Quantico Marine Corps Base but it´s not on display there. All other Ho-Ro were destroyed postwar.


the captured vehicle after transport to Aberdeen Proving Ground

The Type 4 Gun Tank Ho-Ro was developed as heavy assault gun for direct fire. For this task it was too high and armor was too weak. The gun was able to destroy everything in the US arsenal with its HE-power. But the low muzzle velocity of 282 m/sec made it hard to hit moving targets and firing speed was slow due to the seperate ammunition. There were no special anti-tank grenades. Nevertheless the vehicles were quite effective on Luzon.

Data

as Type 97 Medium Tank Chi-Ha except
vehicles built: between 12 and 25
battle weight: 16,3 (metric) t
crew: 6 men
height: 2360 mm
power/weight ratio: 10,4 hp/t
armament: 1 X Type Meiji 38 150 mm Howitzer
ammunition capacity: 28 150 mm grenades and charges

armor strength
fighting compartment front
25 mm @ 70 °
sides
10 mm @ 90 °
rear
none
top
12 mm @ 0 °
superstructure front
25 mm @ 70 °
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

g) Experimental Type 4 Gun Tank Ho-To:


only known Picture

Parallel to the development of the Type 4 Gun Tank Ho-Ro the development of a gun tank using the also obsolete Type 38 120 mm Howitzer was started, too. The vehicle was based on the Type 95 Light Tank Ha-Go. The tank was modified in a similar way. Turret and superstructure of the fighting compartment were removed. A gun shield was mouted sloped on the upper bow armor. The sides were bend to the rear. Two side plates completed the armor. It is unclear if there was a top armor but it is most likely. A driver´s visor port was mounted on the right side below the gun. The bow gunner was removed. A hatch for the a siple direct fire optic was placed on the left side next to the gun. There is no hatch or visor port for the commander on the gun shield. It is most likely that he used a periscope. In each side armor plate a small hatch opening to the rear is mounted. The rear of the fighting compartment was open. Gun and the upper lafette were mounted in a trestle riveted to the gun shield.

Armor strength is unknown but it can be assumed that it was similar to the basic vehicle (12 mm maximum) due to the weight limitations of the suspension. Gun and fighting compartment armor lead to an operational weight of 8,5 t. To cope with this higher weight production vehicles should use tracks with a width of 450 mm.

Design was not finished before February 1945 and a prototype was finished in July. First functional tests showed that the stress on the vehicle structure during firing was less than expected. There were no special AP-grenades but the development of a HEAT grenade was started in mid 1945.

Further data and the fate of the prototype are unknown.

Data

as Type 95 Medium Tank Ha-Go except
Weight: 8,5 t
armament: 1 X Type Meiji 38 120 mm Howitzer


h) Experimental Type 5 Gun Tank Ho-Ru:

no picture, sorry



In February 1945 the decision was made to develop a light tank destroyer based on the Type 95 Light Tank Ha-Go using the Type 1 47 mm Tank Gun. The vehicle height should be as low as possible. Turret and superstructure of the fighting compartment were removed and replaced by an octogonal (some sources say hexagonal) armour. At least the forward 2/3 received a top armour. The gun was mounted slightly offset to the right replacing the bow gunner.

Prototype production started in April 1945, tests started in June.

There are several drawings and scale model kits each with massive differences. There is no evidence that any of these shows the real prototype. Armor scheme and other details are unknown.

Data:

As type 95 Light Tank Ha-Go exept
armament: 1 X Type 1 47 mm Tank Gun

Yours

tom!

 

Thank you, Sir.

 

13) Gun Carriers

Following the IJA designation system infantry and cavalry were not allowed to operate tanks or vehicle based on tanks. So those vehicles were designated "Armored vehicle", "Gun Carrier" or received a designation based on their special purpose. "Gun Carriers" were all vehicles using tank chassis or suspensions and armor independend from the armament (artillery, anti-tank or anti-aircraft gun).

During the Siberian Incident 1919-21 IJA units mounted light field artillery guns or mountain guns on trucks and prime movers to increase their mobility. These vehicles were not too effective due to the instability of the wheeled vehicles as gun platforms but they were fast and also had a psychological effect. In the mid 1920th IJA decided to start a massive mobilisation program but due to the limited ressources regarding industrial capacities, raw materials an money special gun carrying vehicles were not developed. This changed with the beginning of the China Incident in mid 1937. First projects and prototypes were not successful and due to the war production ressources became low again. In 1942 the situation changed once more. IJA decided to start a massive military program to fill the gap in tank technology. In addition the anti-tank doctrine was changed, too. Now gun carriers with large caliber anti-tank guns and self-propelled artillery guns were also in focus.

Many vehicles remained designs only, others were built as prototype but only one was adopted officially for serial production. Here I will focus only on vehicles which were buit at least as prototype.

Data on gun carriers and pictures are generally rare.


a) Experimental 3,7 cm Gun Carrier So-To:

no picture, sorry


Details do not fit 100%

After introduction of the Type 97 Tankette Te-Ke the idea came up to use this vehicle to mobilise light infantry support weapons like AA-machine cannons and the Type 94 37 mm Rapid-Fire Infantry Gun (IJA official designation for what is also known as Type 94 37 mm AT-Gun). These weapons were designed light-weight for easy and fast man-drawn transport on the battlefield. So the Type 97 Te-Ke would have been able to carry them.

Removing the turret wouldn´t have been enough to allow operating the guns on the tank. So the vehicle was lengthened by adding a fifth roadwheel which was attached to the rear idle wheel with a bogie.The driver´s armour was changed to a box shape and heightened. For close defence an armored extension with a standard MG port was added next to the driver on the (in driving direction) right side. The forward upper edges were arranged sloped. An access hatch for driver and gunner was mounted in the forward top armor. The gun platform was a little bit lower than the crew compartment to increase crew protection at the now vulnerable space below the gun shield. It is unknown if there was an access hatch on the gun platform or the rear but it is most likely. Armor strength is also unknown but did not exceed the basic vehicle armour (up to 16 mm).

On the vehicle two u-shaped profiles were mounted for the gun wheels. The rear parts could be drawn out to tow the gun on and off the vehice easily. On the vehicle the gun was fixed with clamps on the wheels and the trail.

Further details and data are unknown but at least one prototype was built.

Later the idea came up to remodel the vehicle for more crew protection. The gun should be mounted without gun shield behind an armour plate on the rear of the vehicle. This project was stopped during the design stage.

Data:

unknown


b) Experimental Anti-Aircraft Tank No. 1 Ki-To:



At the same time as the 3,7 cm gun carrier a second version carrying a Type 98 20 mm Automatic Gun was developed and built as prototype. There are some differences to the So-To:

at least
- no u-shaped profiles as the gun was mounted on the vehicle operational.
- two small armor plates behind the crew compartment
- two fastening rods on the rear armor for the wheels of the gun

At least two vehicles were built and tested in 1940. The concept was found good but the crew positions were too vulnerable to enemy fire and splinters. It became clear that more armor protection was necessary

The fate of the prototypes is unknown.

Data:

unknown


c) experimental Type 2 Gun Carrier Ku-Se:

No picture, sorry

In 1944 a gun carrier using a Type 99 Tank Gun and the chassis of the Experimental Type 5 Light Tank Ke-Ho was under development. The designation indicates that the design order was already given in 1942. Most data are lost at surrender but it seems that at least one prototype was finished in summer 1945.

A 20 mm gun shield and short 12 mm side armour plates replaced the turret similar to the Ho-Ni series. The gun was installed in the gun shield with the standard mount as used with the Type 2 Gun Tank Ho-I. To increase armour penetration a HEAT grenade was developed at surrender.

In literature the vehicle is often mentioned with the short designation "Kusae" which is wrong. There is also an artist impression on the internet showing a vehicle with a chassis similar to the Type 1 Chi-He which is far from reality.

Data

unknown


d) experimental Anti-Aircraft tank No. 2 Ta-Se



In 1943 a new anti-aircraft tank based on the Type 98 Medium Tank was developed. There were some changes made with the vehicle:

at least
- a box-shaped armor extensions added above the tracks on each side of the fighting compartment for additional ammunition
- turret replaced by a slightly conical, circular turret with a box-shaped extension on the rear.
- main armament a Type 98 2 cm Automatic Gun
- elevation was enlarged to 90 °
- no gun shield, so a very vulnerable gun position in the turret

The prototype tests were quite successful regarding the vehicle but the vulnerable open gun position was disliked. In addition the Type 98 machine cannon wasn´t really suitable to damage or destroy enemy aircraft any more. Therefore a newly designed, more powerful 2 cm machine cannon was tested.



Still the destructive power was rated too weak and so the design was cancelled.

Data:

unknown


Yours

tom!

 

e) Experimental Anti Aircraft Tank No. 3 So-Ki:



After the development of the Ta-Se was cancelled a similar design using a Type 4 2 cm Twin Automatic Cannon was tested. The vehicle was changed again:
- the turret was removed.
- semi-high armor plates were placed around the now open fighting compartment with the side armor being able to be lowered to enlarge the crew space
- a gun shield gave protection from the front
- a large ammunition box with a bench seat above it was placed in the rear of the fighting compartment

Test showed again that the 2 cm caliber was outdated even using two barrels. As IJA officials disliked medium caliber anti-aircraft guns the whole project was cancelled.

Data:

unknown


f) Experimental Type 4 Heavy Mortar Carrier Ha-To:



In December 1942 IJA ordered the development of a gun carrier to mobilise the new muzzle loaded Type 3 30 cm Trench Mortar. This gun was developed to fire 170 kg HE-grenades with a smooth-bore barrel over short ranges (maximum range 3145 m) for massive fire support during attack or defense. Muzzle velocity was 183 m/sec. The massive gun weight of 5 t made a large carrying vehicle necessary.

So in 1943 the decision was made to use the chassis of the Experimental Heavy Crawler Truck Chi-So which used the suspension of the Type 4 Tank Chi-To. This vehicle had an armored driver cabin with a maximum armor of 12 mm. The rear 2/3 were load space.

The gun was mounted with a hinged loading crane on the rear of the vehicle. The loading mechanism was operated with a supporting hydraulic system. During moving the whole gun was lowered on the drivers cabin. Before firing it had to be erected. A circular base plate lowered to the ground below the barrel was used for stabilisation. The firing angle was fixed at 50°. Range was regulated by the size of the used propellant charge. To minimise stress on the vehicle stucture traverse was limited to 3,5° to each side. Due to the necessary preparation time a fast change of the firing position was not possible making the vehicle vulnerable for counterbattery fire.


firing position

The prototype was finished in late 1944. In early 1945 three more pre-production vehicles were built. At the same time IJA already used heavy 20 cm and 40 cm rocket launchers for the same purpose. Compared to these very simple weapons which were easy and cheap to operate from simple wooden launch platforms the mortar vehicles were expensive to produce and much more vulnerable to enemy fire. So the project was ceased. One vehicle was sent to Aberdeen Proving Ground after surrender. All were scraped.

Data:

vehicles built: 4
weight: 14,3 (metric) t
crew: 7 men
length: 6800 mm
width: 2400 mm
height: 2750 mm
ground clearance: 400 mm
engine: Mitsubishi Type 100 8-cylinder Diesel engine
power: 165 hp
maximum speed: 40 km/h on roads
armament: 1 X Type 3 300 mm Trench Mortar


g) Experimental Type 5 7,5 cm Gun Carrier Na-To:



After ceasing the development of the 57 mm gun in 1942 IJA lacked a larger caliber anti-tank gun able to defeat future enemy medium and heavy tanks. Therefore the decision was made to develop a new 75 mm at-gun.

The results of the predecessor development were still present. IJA standard doctrine was that all support weapons had to be light enough to be manhandled easily. This would be impossible for a larger caliber gun. It was well known that such a gun would be very heavy (above 1000 kg) and unhandy. On the other hand too strict weight limitations also limits the possible power of the gun.

Development started on February 23rd 1942. First studies were made until April 1943 showing a vehicle-drawn standard at-gun with an estimated weight of around 1500 kg. IJA still disliked the idea of such a heavy gun. So the decision was made to develop a tank hunter similar to the german Marder-series instead for better mobility. Basic vehicle should also be the Experimental Heavy Crawler Truck Chi-So. The gun should be based on the AA-gun under development in 1943 which became Type 4 75 mm AA-Gun. Gun development started in mid 1943.

The result was a potent gun with the following data:

- length: 4230 mm
-barrel weight: 761 kg
- lafette weight: 1150 kg with a 12 mm thick, rectangular gun Shield
- total weight: 1845 kg
- recoil length: 1250 mm
- recoil reaction: 3000 kg
- grenade weight: 6,6 kg
- muzzle velocity: 830 m/sec
- elevation: -8° to 19°
- traverse: 20° to each side
- penetration: as Type 5 75 mm Tank Gun


first gun prototype

The gunner sat on the (in driving direction) left side of the gun, the commander on the right side. Four loaders and the driver completed the crew.

The gun was mounted behind the driver´s cabin on a closed ammunition rack. On each remaining side of the fighting compartment 12 mm armor plates were mounted. The side armor was as high as the cabin in the forward 1/3 for better protection. A large two-door access hatch was mounted in the rear. The whole fighting compartment could be covered with a canvas.

Gun tests started in July 1944, vehicle tests in January 1945. Then IJA decided that producing a special gun for such a vehicle would be a waste of the scarce production capacities avaliable. So the gun design should be changed to allow usage of the Type 5 75 mm Tank Gun barrel and recoil mechanism. So the gun had to be remodelled. The result had the same firepower but due to the more massive recoil mechanism the gun shield had to be enlarged. The data were the same except:

- barrel weight: 840 kg
- lafette weight: 1770 kg with a 12 mm gun Shield
- total weight: 2680 kg
- recoil length: 400 mm
- recoil reaction: 8400 kg


second gun prototype

First gun tests started in May 1945. Later that month a complete prototype tests started. These showed that the gun mount suffered from the recoil forces. Therefore it had to be reinforced which was done until July 1945. A second vehicle was finished in July, too. Both vehicles were used for crew training. Until surrender preparations for serial production were started which should have started in September.


prototype during firing Tests

The fate of the prototypes is unknown.

Besides its size and the low armor strength the Na-To would have been a good tank hunter. The gun was able to penetrate even heavier vehicles on medium ranges.

Data:

vehicles built: 2
weight: 13,7 (metric) t
crew: 7 men
length: 5700 mm
width: 2400 mm
height: 2640 mm
ground clearance: 400 mm
ground preasure: 0,66 kg/cm²
trench crossing capability: 2500 mm
climbing capability: 30°
fordability: 700 mm
turning radius: 10 m
engine: Mitsubishi Type 100 8-cylinder Diesel engine
power: 165 hp
maximum speed: 40 km/h on roads
armament: 1 X Type 5 75 mm Anti-Tank Gun

Yours

tom!

 

14) Army Amphibious Tanks:

A less known fact is that IJA was quite busy developing amphibious vehicles in the 1930th. Starting with the the Experimental Amphibious Halftrack AMP at least five different vehicles were developed and tested. As all trials were finally cancelled informations are rare.


a) Ishikawajima Amphibious Tank:



The tests with the AMP showed that such a vehicle would be useful for reconnaissance duties. So after introduction of the Type 92 Heavy Armoured Car Ishikawajima was ordered to develop an amphibious version of this tank, too. This was done until 1933. The official designation is unknown.

The vehicle used suspension, turret, engine and steering from the Type 92. The armour scheme was changed massively. The bow armament extension was removed and the driver was shifted to the center. A boat-shaped hull and large floats on the bow, sides and rear made the vehicle suitable even for heavier swell. Small propellers and rudders next to the tracks allowed manoevring in the water. Armor strength is unknown but did not exceed the basic vehicle (6 mm maximum).

Tests were quite satisfying and a small (unknown) number of pre-series vehicles was built for operational tests, too. Details are unknown but the final results lead to the decision to drop this design in favour of a special development program. The existing vehicles were later used for exercises and then scrapped.

Data

unknown


b) Experimental Amphibious Tank SR I-Go:



After finishing the tests with the Ishikawajima Amphibious Tank IJA ordered Mitsubishi to develop a new design for such a vehicle. Requirements are unknown but it seems that a vehicle weight below 4 t was one of basic demands.

The prototype was finished in 1934. The suspension was similar to the one used on the Engineer Vehicle SS-Ki. It consisted of eight roadwheels, three return rollers, a rear driving sprocket and a frontal idle wheel. Each two pairs of roadwheels were connected by leaf springs and mounted on the hull. The hull had several seperate chambers to retain buoyancy if pentetrated by bullets or splinters. The bow was not really boat-shaped. The driver sat below a cylindrical cupola in the (in driving direction) right. A simple visor port was used. The commander/gunner operated a Type 91 6,5 mm Tank MG inside a small conical turret in the centerline of the vehicle. Both had a large two-door access hatch above their position to enter the tank. All armor plates were riveted.



Afoat a small rudder below the rear allowed steering. Propulsion was generated simply by operating the tracks, there was no propeller. A large hingeable steel plate mounted on the frontal bow armor was used as splash shield.

The final weight without armament and ammunition was just 3,7 t which indicates that the armor strength was very low. During the innitial tests the vehicle reached a maximum speed of 24 km/h on land with a 70 hp gasoline engine. The maximum speed of 9 km/h afloat could only be reached after a long acceleration periode. This propulsion was rated too weak. In addition the small rudder made steering problematic. Armament and armor were also rated too weak. So this design was dropped.

The prototype was used during exercises and was last seen on a parade in China in summer 1938. After development of its successor the numbering suffix "I-Go" = "Version 1" was added to the vehicle designation. Short designation became SR-I with SR = "Suiriku-Ryoyo sencha" = "Amphibious Tank"

Data:

vehicles built: 1
weight: 3,7 (metric) t
crew: 2 men
length: 4950 mm
width: 2400 mm
height: 1650 mm
engine: Mitsubishi 4-cylinder gasoline engine
power: 70 hp
maximum speed: 24 km/h on roads, 9km/h afloat
armament: 1 X Type 91 6,5 mm Tank MG


c) Experimental Amphibious Tank SR Ro-Go:[/U]



The problems with the SR-I led to the decision to start a new trial in late 1934. This time Ishikawajima was in charge of development again. Now weight should be up to 7 t, maximum armor strength 10 mm. A second MG should increase firepower.

The prototype was finished in mid 1935. It had a completely new Horstmann-type suspension consisting of three roadwheels, one return roller, a frontal driving sprocket and a rear idle wheel. The two forward roadwheels were connected by a small coil spring and a bogie. The rear roadwheel was connected the same way with the idle wheel. The return roller was placed between the second and third roadwheel. The bow was now boat-shaped increasing acceleration afloat. An armor plate integrated in the middle of the bow armor could be raised as splash shield.

On the bow and each side several flotation chambers were mounted. These were designed flatter to lower the silhouette. The driver now had a rectangular cupola with visor ports on the front and right side. He entered the vehicle through a large rectangular hatch above his position. On his left side the bow gunner was placed below a slightly larger rectangular cupola. A cap on his hatch increased his firing angle. He operated a Type 91 6,5 mm Tank MG in a standard mount. A closable visor port was placed in the left side next to the gunner.

The turret had an octogonal basic shape with sloped sides. A standard MG mount for a Type 91 6,5 mm Tank MG was mounted in the frontal plate. Closable visor ports were placed in each forward side and side armor plate and in the rear. The commander/gunner entered the tank through a large access hatch with a big cap. A grid construction behind the turret simplified access to the vehicle afloat.



The engine was placed lengthwise in the rear. Exhaust pipes lead from the rear to a muffler and raised tail pipes behind the turret on each side. Two 500 mm propellers with rudders were attached to the rear.

The vehicle was designated "SR Ro-Go" = Amphibious Tank Version 2, short designation SR-II. During innitial tests the vehicle showed a good mobility on land and afloat. A small pre-production series was finished until late 1935. Operational tests were successful but the armament was rated too weak. Nevertheless the concept was rated good.

The fate of the vehicles is unknown. At least one was captured 1945 by soviet units in Manchuria. There is no known survivor.

Data:

vehicles built: 1
weight: 6,9 (metric) t
crew: 3 men
length: 4100 mm
width: 1800 mm
height: 1600 mm
engine: gasoline engine
armament: 2 X Type 91 6,5 mm Tank MG


d) Experimental Amphibious Tank SR Ha-Go:



In late 1935 Mitsubishi was ordered to remodel the SR-II design. Goal was to increase firepower and armor. Only limit was a maximum weight of 7,5 t.

The basic shape reminds of a Vickers Light Amphibious Tank. One was captured in China and it seems that many design features were copied. To get a stable gun platform afloat the flotation chambers were enlarged to the sides and front. Welding was used instead of rivets as far as possible to spare weight. The maximum armor was increased to 13 mm. The turret was similar to the Type 94 tk turret. A prototype was built until mid 1937 designated "Amphibious Tank Version 3", short Designation "SR-III" or "SR Ha-Go".

Trials to mount a Type 94 37 mm Tank Gun lead to a maximum weight above 7,5 t. This was also rejected as the proposals to mount a Type 92 13,2 mm Tank Machine Cannon or to lower the armor strength to reach 7,5 t. Both guns would have needed a larger turret. Mitsubishi saw no chance to archive the expected result with the weight limit. In addition there was a lack of ressources regarding production capacities, raw materials and money. So IJA decided to cancel the whole project in 1938. The development results were handed over to IJN.

The prototype was sent to Rabaul in 1942 or 1943 for further tests and transport purposes. The remains are on display at Kokopo Museum, Rabaul.

Data:

vehicles built: 1
weight: 7,5 (metric) t
crew: 2 men
length: 4100 mm
width: 2000 mm
height: 1800 mm
engine: gasoline engine
armament: 1 X Type 91 6,5 mm Tank MG


Yours

tom!

 

15) Engineer AFV

Since the early 1930th a number of special vehicles for different tasks were developed and built. Among these a few were used by IJA engineers. These included chargelayers, obstacle removing and mineclearing tanks. The remote controlled vehicles are subject of a later post.


a) Armored Working Vehicle SS:



During the late 1920th the Soviet Union was rated the biggest danger for the japanese plans in East Asia. So with the new development and mobilization plan from 1929 a specialized engineer vehicle able to destroy bunkers and roadblocks should be developed. Design started in 1930 at 2nd Army Technical Bureau based on the technologies gathered during the development of the Experimental Tank No. 2 and the early design stages of the Type 89 Medium Tank. Because of the problematic financial situation instead of just two tasks the vehicle should be able to fulfill several:

- bridge laying
- mine clearing
- obstacle removing
- gas and decontamination agent scattering
- charge laying
- crane operating
- trench digging
- smoke laying
- flame oil throwing

Therefore a versatile and mobile vehicle with several modules for the different tasks was developed. The suspension was similar to the Type 89 Medium Tank with two sets of two pairs of small, bogie connected roadwheels sprung by large packs of leaf springs each. A large driving wheel was at the bow, a large idle wheel in the rear. Four return rollers completed the suspension. The armor was between 6 and 25 mm thick. The frontal armor had a sloped center part, a vertical lower part and an almost vertical upper part. On the left side of the upper armor a large mount for a Type 93 Flamethrower was added. The driver´s visor hatch on the right was openable to the top. The side armor was vertical with the upper part arranged sloped. Diagonal armor plates connected the sides with the bow and rear armor. The rear armor was vertical. A hemispherical commander’s cupola was mounted centered on the forward top armor. The suspension was covered by 6 mm trapezoid armor plates . A large, two-part access hatch in the top armor allowed engine change. The rear engine compartment was accessible from the forward fighting compartment, too. A 105 hp gasoline engine was used which should be replaced by a Diesel engine as soon as possible.


Version Hei with explosive charge mounted on the bow

There were several attachment points on the bow, top and rear. On the bow mine forks plus an obstacle clearing wedge or a 300 kg explosive charge could be added. On the top a crane, smoke agent canisters and/or two different types of bridges (7 m straight bridge and 10 m scissor type) could be carried. On the rear a fluid tank for chemical agents or flame oil or a large trench plough could be attached. The chemical agents could be dispersed by a spray nozzle attachable inside the flame thrower mount. The vehicle was able to fulfill all demanded tasks but not at the same time as some modules couldn´t be used parallel.

First operational tests started in 1933. In 1934 two vehicles were send to China to be tested at 1st Mobile Brigade. Due to the available space inside the vehicle the new Type 94 Model 4 radio set was added in 1935. Several necessary changes and a low priority delayed official introduction until 1936. As this vehicle was developed for engineer units which were not allowed to operate “tanks” the designation “Soko Sagyosha” = “Armored Working Vehicle” was chosen, short designation “SS”.

There were five versions during the years:

Version Kou(A) = A:



Basic production version with a 140 hp gasoline engine. 13 were built.


Version Otsu = B



Version Otsu had a modified suspension with one return roller removed, and modified driving and idle wheels. The vehicle seemed to be specialised to flame throwing. Four small, armored flame oil tanks were mounted fixed between the suspension parts. Due to the tanks the suspension armor could not be used any more. A concrete made flame oil tank was added to the rear. An additional flame thrower mount was implemented in the remodeled forward side armor. In addition the bow armor was remodeled similar to the Type 89 tank with a sloped lower part and a vertical upper part.

The commander´s cupola was now quadrangular with sloped sides and a two-part hatch on top. 8 vehicles were built


Version Hei = C



Version C was a remodeled Version A. The suspension also had three return rollers and modified driving and idle wheels but the flame oil tanks were not used. The suspension armor consisted of several welded armor plates instead of a harder to produce single plate. The two additional flamethrower mounts were placed in the forward side armor. The commander´s cupola was hemispherical again. The now used Mitsubishi I6 Diesel engine with 145 hp at 1800 rpm allowed a maximum speed of 37 km/h. 1 vehicle was built


Version Tei = D



Version D was a remodeled version B. Driving wheels and idle wheels were modified again to spare weight. The shape of the driver´s hatch and the bow flamethrower port were modified and a standard MG mount for a Type 97 7,7 mm MG was added between them for better close defense. The Type 93 flamethrowers were later replaced by the lighter Type 100 Flamethrowers. The commander´s cupola was now conical. And the Diesel engine was used. 20 vehicles were built.


Version Bo = E



Modified version D. The suspension was simplified by removing another return roller and the armor plate wasn´t used any more but suspension side armor was increased to 13 mm. The commander´s cupola was now cylindrical. Armament consisted of three standard infantry Type 100 Flamethrowers and a Type 97 7,7 mm MG. 77 vehicles were built.


The need to exchange the modules for different tasks finally leads to the decision to develop special purpose-built vehicles as replacement around 1940. None of these developments was introduced. They will be covered in a different post. Several Independent Engineer units and after 1942 especially the tank division engineers were equipped with the SS.

Data:

vehicles built: 119
weight: Kou(a) 9,6 (metric) t , Otsu 9,8 t, Bo 13 t
crew: 5 men
length: 4865 mm
width: 2520 mm
height: 1800 mm
armor: 6 – 25 mm
engine: Kou(A) 120 hp gasoline, Hei 145 hp Diesel
maximum speed: 37 km/h on roads
armament: 1 – 3 X Type 93, later Type 100 Flamethrower; 1 X Type 97 7,7 mm MG for Hei and Bo


b) Type 95 Crane Vehicle Ri-Ki



Informations on this vehicle are also rare. In 1935 the decision was made to develop a special crane vehicle for heavy engineer duties. The suspension was similar to the Type 97 Medium Tank Chi-Ni with four pairs of small roadwheels. The engine was placed left of the driver in the armored driver´s cabin. On the rear a medium size, 3t boom crane with a 4,5 m jib was mounted turnable. Crew consisted of driver, commander and crane operator.

Data:

weight: 7800 kg
crew: 3 men
length: 5620 mm
width: 2000 mm
height: 2280 mm
armor: 6 mm
engine: 60 hp gasoline
maximum speed: 32 km/h on roads

Yours

tom!

 

c) High Voltage Dynamo Vehicle Ka-Ha:



In late 1938 a special vehicle for the destruction of enemy wire based communication equipment was developed. It was based on the Type 97 Medium Tank Chi-Ha. The superstructure was heightened to allow mounting a generator and a 10.000 V alternating current dynamo inside. The bow MG was removed and the driver sat in centerline. A small turret with a dummy gun and a hatch was added to keep the outer shape of a regular tank.

The vehicle was driven to a telephone or telegraph cable and earthed. Then the current was sent into the cable destroying attached equipment and killing users in up to an unknown maximum distance.

A total of 4 vehicles were built and used by the 27th Independent Engineer Regiment in China.


Data:

unknown


d) Type 4 Generator Vehicle:



In 1944 a special generator tank was developed and built, based on the Type 2 Light Tank Ke-To. Main purpose was to deliver power for larger electric machinery like pumps, saws and jackhammers. A large 30 kW generator driven by the vehicle´s engine was mounted inside the fighting compartment. A small cylindrical turret with an extension for a standard MG mount replaced the original turret. A medium sized spotlight was mounted on the rectangular turret hatch. A small crane was placed on the rear of the turret.

25 vehicles were built and tested in 1944/45. None was issued to operational units until surrender

Data:

unknown

Yours

tom!

 

Railroad AFV:

After taking over northeastern China in the late 1920th IJA developed and used several AFV for railway security and repair purposes. Most of these vehicles had more or less complex dual suspensions for road and railroad usage. As IJA High command didn’t wanted to have tanks outside tank units it was not allowed to mount a fixed armament and possible armor strength was limited. Additionally the designation was again just “vehicle” .

There were also armored trains and handcars used by railway regiments and a single railway gun used by a railway artillery unit.


a) Sumida Type RSW Railroad Vehicle:



In the late 1920th IJA ordered Ishikawajima´s Sumida factory to develop a special armored car for railway use. Main purposes should be guard duty, transport, towing of small wagons and armored reconnaissance. The development started under the internal designation RSW using an own 4X2 truck chassis.

The armor consisted of 6 mm face-hardened steel plates riveted to a frame. The armor was mainly arranged vertical with only the upper engine cowling and the driver cabin´s frontal armor arranged sloped. A large cylindrical rotating turret was mounted on the top. There was no fixed armament installed but it was possible to mount the standard light MGs issued to the railway regiments. The MGs could be mounted in several MG ports on each side of the vehicle and the turret.

The suspension was powered by standard gasoline truck engine and transmission. Due to its limited power the heavy vehicle was underpowered and there was just one reverse gear limiting the reverse speed. Road usage was not possible limiting the operational possibilities.

At least one vehicle was produced and tested 1929 in Manchuria. There was no serial production. The whole concept was rated useful even with its several design problems.

Data:

unknown


b) Type 90 Railroad Vehicle:

no picture, sorry

After testing the RSW Railroad Vehicle the decision was made to use a larger 6X4 truck chassis as basis for such a vehicle. Sumida used its Type P Truck to develop a new railway vehicle with better performance. Internal factory designation was “Type PA”.

The prototype was similar to the parallel developed Type P Armored Car but it had no rubber rings on the steel wheels making road usage still impossible. The more powerful engine allowed a maximum speed of 40 km/h forward but due to the single reverse gear reverse speed was still low. A coupling on bow and rear allowed connecting railway cars to the vehicle.

The vehicle was rated superior to the RSW and so the official introduction followed 1930 as “Type 90 Railroad Vehicle”. Production number is unknown.

Data:

unknown


c) Type 91 Broad Gauge Railway Vehicle:



Updated version of the Type 90 Railway Vehicle. Main changes were an enlarged fighting compartment and special rubber tires for road usage. To change from railway to road and vice versa the vehicle was lifted by two large hydraulic jacks on bow and rear. Then the steel tires for railways were exchanged by the rubber tires for roads or reversely. The wheels could be mounted with spacers if necessary. With them it was possible to use the vehicle on standard gauge and broad gauge railroads.

The transmission still had only 5 forward and one reverse gear making it slow driving backwards. So most of the time the vehicles were used in pairs connected with their rear couplings. That way there was always one driving forward.

Again no fixed armament was mounted but it was possible to use standard infantry MGs through several ports around the armored body. Armor strength was only 6 mm making it hard even to defeat infantry ball ammunition on shorter ranges. Total weight with a 6-cylinder gasoline engine was 7700 kg.



Production started 1932 at Ishikawajima´s Sumida factory. A total of around 1000 vehicles were built. They were issued to Railway Regiments bound for continental services and garrison units of the South Manchurian Railway Company. Main usages were armed transport, guard duties and railway repairs. During the 2nd Sino-Japanese War some vehicles were also used for armed reconnaissance on railways.

Data:

vehicles built: ca. 1000
weight: 7700 kg
crew: 4 men + 2 passengers
length: 6580 mm
width: 1900 mm
height: 2950 mm
armor: 6 mm
engine: 75 hp gasoline
maximum speed: 65 km/h on roads 40 km/h on railroads
armament: none, infantry MGs could be mounted in several gun ports around the Body


d) Type 95 Armored Railway Vehicle So-Ki



In 1934 a special vehicle for railway engineers was ordered for the South Manchurian Railway Company. It should be able to use narrow, standard and broad gauge railroads. To increase cross-country abilities a tracked suspension should be used off the railroads. The change between the suspensions should be done easily and quick. For better crew protection the armor should be up to 8 mm thick. Tokyo Gas and Electric (TGE) was ordered to develop the vehicle.

The resulting proposal was a tankettes-style vehicle similar to the Type 94 tk Special Tractor but larger. The tracked suspension was a TGE development from the early 1930th. It was similar to the Armored Working Vehicle SS and consisted of two sets of two pairs of roadwheels. Each pair was connected by a bogie and each two pairs were connected to a large leaf spring package. Forward driving wheels and rear idle wheels were used as well as three return rollers. The railroad suspension consisted of four steel wheels on two axles mounted inside the vehicle. Steel plates covered the moving parts. The gauge could be easily adjusted by pushing the wheels along the axles to special fixing points. Then the whole construction was lowered to the tracks through holes in the lower armor by a hydraulic system able to lift the whole vehicle. Changing to railroad suspension took 3 minutes, to ground suspension 1 minute.



The armor scheme was similar to the Type 94 tk but without the armor extension on the bow and the driver´s visor port integrated in the upper superstructure armor. A small slightly conical turret with a gun port in the front side was mounted centered on the fighting compartment. There was no fixed armament but a standard infantry MG could be mounted.

In early production a TGE DB51B 6-cylinder gasoline engine was used. Later it was changed to an Isuzu DA6 6-cylinder Diesel engine with 84 hp, allowing a maximum speed of 72 km/h on railroads

Main purpose of the vehicle was armored transport of men and material to damaged tracks. Two couplings on the front and the rear allowed towing of light wagons or the Type 91 Railway Vehicle. A total of 121 So-Ki were produced by TGE and Mitsubishi. One vehicle remained at the Kubinka Museum near Moscow and another one in a museum in Beijing.

Data:

vehicles built: 121
weight: 9800 kg
crew: 6 men
length: 4900 mm
width: 2560 mm
height: 2540 mm on railroads, 2430 mm on the ground
armor: 4 - 8mm
engine: gasoline, later 84 hp Diesel
range: 250 km on roads, 123 km on railroads
maximum speed: 72 km/h on railroads, 40 km/h towing, 30 km/h on roads, 20 km/h offroad
armament: none, infantry MGs could be mounted in several gun ports around the body


e) Type 95 Railway Crane Vehicle



This vehicle is not well known and informations are rare. After developing the Type 95 So-Ki TGE was ordered to develop a special lightly armored crane vehicle using the same railroad suspension. This time the suspension of the type 89 Medium Tank was used for ground travelling. A lightly armored superstructure was added with a semi-open driver´s cabin in front and the engine in the rear. On the center of the vehicle a 5 t boom crane for railway repairs and recovering of trains was mounted. Production data are unknown.

Data:

unknown


Yours

tom!

 

17) Remote Controlled Vehicles

a) Nagayama Tank:





In 1929 engineer corps Major Nagayama suggested to use unmanned, radio-controlled vehicles for dangerous tasks like mine clearing and charge laying. Until early 1930 a Fordson Model F tracked prime mover was reworked as lightly armoured vehicle. The tractor was covered with face-hardened armour plates able to defeat infantry AP ammunition. The 20 hp gasoline engine was placed in the center. The steering mechanism was placed in the forward part. On the rear a payload container e. g. for ammunition or an explosive charge could be mounted.

The radio equipment was mounted in a superstructure in the center of the vehicle. The control orders were transmitted by a modified infantry radio powered by lead accumulators. Two antennas on the superstructure received and transmitted data. Further details are unknown.


control equipment, note the large number of accumulators

In late February 1930 a public demonstration was made at Tokyo Army Arsenal. The tank was a sensation in european and US newspapers. The development was discontinued most likely due to the limited mobility of the suspension but the basic idea was rated useful. The fate of the prototype is unknown.

Data:

unknown


B) Remote-Controlled Type 94 Special Tractor TK

no picture, sorry


After the tests and trials with the Nagayama Tank were finished in the early 1930th the decision was made to continue development using a Type 94 Special Tractor in 1935. The conversion of the prototype was done fast and first tests were successful. So the decision was made to convert at least a second vehicle for operational tests. Further data are unknown. In 1936 the vehicles were reconverted to the standard configuration. The concept of a radio-controlled vehicle was also abandoned in favor of remote-controlled vehicles using electrical commands transmitted by cables.

Data:

unknown


C) Type 98 Miniature Engineer Vehicle Ya-I-Go



In 1932 Scientific Research Section No. 1 of Army Technical Bureau proposed the development of a remote-controlled tracked vehicle to fight enemy pillboxes and fortifications by laying explosive charges. Control orders should be send to the vehicle through a multipolar cable. The charge should be jettisoned close to the target. Then a 30 second delay should be started firing the charge. During the delay time the vehicle and the command tank should leave the blast radius. The Type 89 Medium Tank should be used as basis for the carrier and the command tank. The first design did not reach the prototype stage due to mechanical and electrical problems.

In 1933 the concept was still rated good and a second development program was started on a wider base. But instead of a large tank a small electrically powered tracked vehicle should be developed. Works started in late 1933. The vehicle frame was made out of a light-weight but very stable Aluminum-Silicon alloy. Suspension consisted of two pairs of small roadwheels, a fifth raised forward roadwheel to increase cross-country maneuverability, a forward idle wheel, a rear driving sprocket and two return rollers. Tracks with 87 links were used. Two watertight 600 V electrical engines delivering 1 hp each were placed in the rear half inside the frame. Each engine powered one of the tracks. The control/power cable reached the vehicle from the rear. A barrel with a cone on its end was mounted on the vehicle as strain relief. On the bow was a metal box for the explosive charge. The cable had 13 wires, two for power supply and 11 for control commands. It was covered by a layer of rubber and hamp fabric. For an easier transport cable segments of 250 m length were used which could be connected. Maximum allowed length of a connected cable was 500 m on even ground. Cross-country only one cable segment should be used. The total height was just 460 mm, length 1425 mm. With a 35 kg charge the total weight was below 200 kg. On roads up to 18 km/h were reached, 4 km/h cross-country.

During first tests in 1935 the vehicle worked very well. Nevertheless several changes were done. The cable was additionally surrounded by a dense wire mesh for additional stability and protection against splinters. This allowed to use cables with up to four segments increasing the maximum range to 1000 m. Cross-country the range should not exceed 750 m. The charge was rated too weak against pillboxes. So a charge of 40 kg using stronger explosives was developed. The metal box on the bow was removed and the charge was mounted directly on the bow. In addition a Bangalore-type charge with a length of 1075 mm and a 2,7 kg charge was developed to be used against wire entanglements and obstacles. Additional mounts for smoke canisters were added on the vehicle. This vehicle was introduced in 1937 under the designation "Type 97 Miniature Engineer Vehicle" and received the short designation "I-Go"

The 40 kg charge was still too weak against thicker bunker walls. So the decision was made to develop a larger version, too. It used the similar basic scheme but the roadwheels were bigger. In addition two 2 hp engines were used to cope with the total weight of 400 kg. A charge of up to 300 kg could be carried. An improved Bangalore-type charge with a length of 1151 mm and a 3,2 kg charge was introduced, too. In addition low-power shaped-charge warheads for these charges with a penetration of 30 mm steel and 110 mm concrete were also developed. This vehicle was introduced in 1938. The official designation of both vehicles was changed to "Type 98 Mini Engineer Vehicle", short designation became "Ya-I-Go". The small vehicle received the additional designation "Version Kou(A)", the bigger one "Version Otsu".

​

rear view, the upright stick on the rear is the body of a Bangalore charge.

The first unit using this vehicles was raised in early 1939 and stationed in Manchuria. A squad consisted of 12 men which operated a vehicle, a second was held in reserve. Besides the charge layers equipment consisted of a generator vehicle based on the Type 94 6-wheel Truck and several standard Type 94 Trucks for vehicle and equipment transport. For version Otsu a special armour shield made of 5 mm face-hardened steel was introduced to allow carrying a human observer under protection. An auxiliary generator vehicle based on version Otsu for heavy terrain was developed, too. This was replaced in 1943 by a generator vehicle based on the Type 98 Transport Tank So-Da. A standard attack was done by three squads. The first blows wire entanglements with the version Ko, the second destroyed obstacles with the version Ko and the third finally destroyed the bunker with a version Otsu. Standard starting position was between 200 m and 500 m away from the target. During exercises ranges up to 1500 m in easy terrain were reached. Larger ranges caused a current drop due to the cable resistance stopping the engines.

In 1940 the units stationed in Manchuria were combined to 27th Independent Engineer Regiment. The nominal strength was around 2000 men operating 108 chargelayers of both versions. The rest of the 300 production vehicles was stored in Japan for homeland defense. In April 1945 27th Independent Engineer Regiment was relocated to Honshu for the expected homeland decisive battle. At surrender the unit sunk their vehicles in rivers and lakes. The others were destroyed, too. There is no known survivor.

There were also versions tested for attacks on targets in the water and with larger charges towed behind the vehicle. None was introduced.

Data (Ko/Otsu)

vehicles built: 300
battle weight: 200 kg / 400 kg
crew: unmanned, one person could be carried with version Otsu
length: 1425 mm / 1980 mm
width: 635 mm / 1170 mm
height: 460 mm / 560 mm
trench crossing capability: 850 mm / 1100 mm
climbing capability: 40° / 30°
engine: 2 X 600 V electrical
power: 1 hp at 2000 rpm /2 hp at 2000 rpm
maximum speed: 18 km/h on roads, 4 km/h cross-country
range: 1500 m on roads, 1000 m cross-country
armament: 1 x 40 kg charge or Bangalore torpedo with 2,7 - 3,2 kg explosive / 1 X up to 300 kg charge

Yours

tom!

 

18) Other Special Purpose AFV

a) Type 97 Armored Cable Layer:



Special version of the late production Type 94 Special Tractor for communication units. The bow armor was heightened but still had the armor extension above the gearbox. The driver sat behind a windshield in an open driver´s and engine compartment with the engine placed on the left. Two hinged armored caps were added for protection against rain or snow.

The rear half of the vehicle was a large storage with components to unwind cable reels. The cable could be unwinded to the rear or redirected to the a small support sustainer on the right bow holding the cable up and so making cable attaching to poles easier. Storages were added for several cable reels. The whole storage could be covered with a canvas.



The total production numbers are unknown but low.

Data:

unknown


b) Type 97 Armored Pole Planter:



Another special version of the late production Type 94 Special Tractor for communication units. It had the same bow as the cable layer and a similar driver´s compartment. But it was covered by a fixed armor plate. The rear storage compartment was covered by a steel roof and had side armor. A collapsible ladder could be erected on the roof to reach the top of higher poles. On each side of the vehicle two pairs of mounts were welded to the driver´s compartment and the rear roof trestle to carry a total of six wooden poles.

On the storage compartment a large earth drill was mounted. The vehicle drilled a hole in the ground, a pole was placed inside it and a cable was attached to the pole. Pole planter and cable layer should work as pairs.

The total production number is unknown but low.

Data:

unknown


c) Type 97 Recovery Vehicle Se-Ri:



Special recovery vehicle based on the Type 97 Medium Tank Chi-Ha. The basic vehicle was identical. The turret was replaced by a smaller conical turret with a round hatch and a standard MG mount in the front. On the rear armor a 2,5 t crane was mounted to tow other vehicles . On the side armor and on the rear storages for additional equipment were placed. A total of 3 Se-Ri were built and used by vehicle test facilities.

Data:

as Type 97 Chi-Ha except
height: 2210 mm
armament : 2 X Type 97 7,7 mm MG


d) Type 97 Command Tank Shi-Ki:



Special command tank based on the Type 97 Medium Tank Chi-Ha. The suspension was identical. The upper bow armor was flat instead of slightly curved. The bow MG was replaced by a Type 98 37 mm Tank Gun mount making a slightly higher superstructure necessary. The turret was replaced by one without a tank gun. Only the rear MG remained but in 180° position. Instead of a gun a small table and additional observation devices were mounted. The commander´s cupola was centered and shifted to the front of the turret .

Production numbers are unknown but low. It is unknown if it was planned to equip each regimental command section with such a vehicle. Only Chiba Tank School used it for unit training.

Data:

as Type 97 Chi-Ha except
armament: 1 X Type 98 37 mm Tank Gun in the Bow, 1 X Type 97 7,7 mm MG in the rear turret


Yours

tom!

 

e) Type 100 Artillery Observation Vehicle Te-Re:



Special observation vehicle based on the Type 97 Tankette Te-Ke. The suspension was identical. The engine was shifted to the right front next to the driver. The fighting compartment was enlarged to the rear and the sides. The commander sat behind the driver under a rectangular conical cupola. On his right side a 0,75 m rangefinder could be mounted on the engine compartment. Crew consisted of up to 8 men: driver, commander, rangefinder operator, protractor operator, observer and 1 – 3 radio operators.

Each mobile artillery battery should receive such a vehicle but only few were built and issued to homeland defence Units.

Data:

weight: 4,9 t
crew: 6-8 men
length: 4070 mm
width: 1990 mm
height: 1900 mm
armor strength: 6 mm
engine: 6-cylinder Diesel engine
power: 65 hp at 2300 rpm
maximum speed: 40 km/h on roads
armament: none


f) Armored Lumberjack Ho-K:



Special construction vehicle based on the Type 1 Medium Tank Chi-He. The basic vehicle was identical. The turret was repmoved and the upper superstructure heightened. A large triangular cutting wedge was mounted on the bow. Main purpose was to cut paths through dense woods under enemy fire. The first production vehicles were issued to 12th Independent Engineer Regiment in Manchuria but later the vehicles were sent to the other theatres as airfield and road construction vehicles.

A total of 40 vehicles were built.

Data:

vehicles built: 40
weight: 15 t
crew: 5 men
length: 7580 mm with nose
width: 2700 mm
height: 1800 mm
engine: Mitsubishi 6-cylinder Diesel engine
power: 240 hp at 2000 rpm
maximum speed: 39 km/h on roads
armament: none


g) Lumber Sweeper Basso-Ki:



Special construction vehicle based on an experimental prime mover. The suspension was similar to the Type 97 Chi-Ha but had only five roadwheels with the rear one mounted separate. In the bow a Diesel engine was placed. On the lightly armored engine compartment two small cranes were mounted to carry chopped trees. Behind the engine the driver´s compartment was placed. The rear half of the vehicle consisted of a storage compartment for tree chopping and removing equipment including a powered chainsaw.

Total production number is unknown. The vehicles should work as team with the Armored Lumberjack Ho-K.

Data:

unknown


More tomorrow.

Yours

tom!

 

19) Experimental Engineer AFV

The following engineer vehicles are less known and most data is lost.


a) Experimental Charge Layer:



A Type 97 Chi-Ha was tested with a retractable massive crane structure mounted on the front of a modified turret. On the forward end of the crane a small charge was placed. Then the crane was extended several meters to place the charge directly inside a bunker through an embrasure. The crane was retracted and the charge exploded destroying the interior. The whole concept only works with larger embrasures like for a gun etc. But this would have exposed the tank to counter fire. The vehicle was not introduced.



Data:

unknown


b) Experimental Obstacle Clearer:



Another trial was to use a Type 97 Chi-Ha as special wire obstacle clearing tank. The turret was replaced by a long turnable firing device for four long Bangalore torpedoes. The vehicle drove near the obstacle and fired a charge at it using a spring mechanism on the rear end of the firing device. Again the vehicle was exposed to covering fire as the range was limited. It was not introduced.

Data:

unknown


c) Experimental Minesweeper G:



A Type 97 Chi-Ha was equipped with an experimental mine clearing device designated Chi-Yu consisting of two flail drums, three girders and a bow mounted lifting device operated hydraulically. The drums where placed in front of the tracks and rotated driven by the driving wheels exploding the mines below it.



Data:

Unknown


d) Experimental Minesweeper GS:

no picture, sorry



Another special purpose vehicle based on the Type 97 Chi-Ha. Development started in 1943. Main turret armament and antenna were removed. It is not sure if the gun or the MG, but one of them was replaced by a spigot type launcher for a small explosive charge against obstacles. On the rear armor a rocket thrower with eight rocket launchers in two rows was mounted angled. Small boxes with explosive ropes were placed below the wire made launching tubes. After firing a rocket the attached rope fell over the minefield and detonated exploding all mines next to it. There are reports of two prototypes tested.

Data:

unknown


e) Experimental Trench Excavator:



Experimental vehicle based on the Type 97 Chi-Ha. The tank was heavily modified. The last road wheel was removed and the idle wheel lowered to the ground to increase track ground contact. The superstructure was replaced by a shorter fighting compartment without bow MG or driver´s extension. A small conical turret with a standard MG mount was placed offset to the left on the new superstructure. Due to a smaller engine the engine compartment was smaller. On the rear a massive construction for a trench plough was added to cope with the forces while trench digging.

At least one prototype was tested in Manchuria and later sent to Wewak where it was found sunk into the sand of a beach. The further fate is unknown

Data:

Unknown

f) Experimental Bridge Laying Vehicle TG:



Special purpose vehicle based on the Type 1 Chi-He. The turret was removed. Instead a bridge laying device for a 1850 kg 9 m bridge was added on the vehicle. The bridge was layed using a fast pulling mechanism based on an aircraft catapult used on Navy ships. The mechanism was powered by combustion gases of gunpowder charges. With it the bridge could be thrown 10 m. To increase this range to 11,4 m small rockets could be added to the front of the bridge. A winch powered by the engine was used to reload the bridge after usage. This took 5 minutes.

Data:

unknown

Yours

tom!

 

20) Other Experimental AFV:

Some more vehicles with almost all data lost.


a) Experimental Lumberjack No. 1:



In 1933 Tokyo Gas and Electric (TGE) was ordered to develop a special tracked armored vehicle able to clear roads through the soviet taiga. The resulting vehicle was similar to the Armored Working vehicle SS but with a TGE developed suspension. A large triangular wedge was mounted on the bow which simply pushed away trees knocking them down and rooting them out. At least one prototype was built and tested but there was no serial production. Later the concept was taken over for the more powerful Armored Lumberjack Ho-K

Data:

unknown


b) Experimental Lumber Sweeper:



This vehicle was a side development of the Experimental Lumberjack No. 1.Purpose was to move away the trees cut down by the lumberjack. It used a similar suspension but with slight differences. On the bow two small cranes able to lift medium loads were placed. The driver sat behind the cranes. The engine was mounted in the rear. The concept was later taken over for the Lumber Sweeper Basso Ki.

Data:

unknown


c) Experimental Glider Tank So-Ra:



Specially designed tank for airborne units. With the delay of the Ku-7 gliders a proposal was made to develop a tank able to fly as glider. The resulting vehicle was small with an aerodynamic bow, a small driver´s cupola a small turret in the center and an engine compartment in the rear. It should be armed with a 3,7 mm gun, a flamethrower or a MG. A detachable empennage could be mounted behind the turret and detachable wings on the sides of the vehicle. The whole construction should be able to be towed with a Ki-57 transport plane. Only a wooden mockup was built in 1943.

Data (planned):

Crew: 2 men
weight: 2,9 t, 4,2 t with aeronautical elements
length: 4070 mm, with aeronautical elements 12800 mm
width: 1440 mm, with wings 22000 mm
height: 1890 mm, with aeronautical elements 3000 mm
engine: 4 cylinder gasoline
power: 50 hp at 2400 rpm
speed: 43 km/h on roads
armament: 1 X Type 1 37 mm Tank Gun or 1 X Type 100 Flamethrower or 1 X Type 97 7,7 mm Tank MG


d) Experimental Gun Tank Ho-Ri:



In late 1943 the decision was made to mount the at this time experimental 105 mm Tank Gun in a fixed fighting compartment on the chassis of a Type 5 Tank Chi-Ri. There are two different versions discussed in the web, one with the fighting compartment in the center, the other with it in the rear. Both have the bow armor of the Chi-Ri.

But the only existing contemporary picture of a wooden mockup shows a vehicle similar to the german Ferdinand with the fighting compartment in the rear and a sloped frontal armor instead of the stepped of the Chi-Ri. This way the vehicle could withstand hits of US 76 mm tank guns without needing a more massive armor. There are no infos about the later development stages so the web discussion is more or less based on fictional facts. There was at least one prototype under construction before surrender.

Data:

unknown


e) Experimental Working Vehicle:



Special construction duty version of the Type 4 Generator Vehicle. The vehicle was largely remodeled to add a dozer blade. It still had a generator for powered tools. Serial production was planned but did not start.

Data:

Unknown

Yours

tom!