IJA Armoured Vighting Vehicles

Hi.

12) Gun Tanks part 3

d) Type 1 Gun Tank Ho-Ni II part 2:

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 @ 75 °
sides 12 mm @ 90 °
rear none°
roof 10 mm @ 0 °
superstructure front 25 mm @ 78 °
sides 25 mm @ 75 °
rear 20 mm @ 25 °
top 10 mm @ 10 °
suspension front 25 mm @ 42 °
sides 25 mm @ 90 °
rear 20 mm curved


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) add 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 °
roof 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 20 mm curved

to be continued in part 4…

Hi.

12) Gun Tanks part 4


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 20 mm @ 90 °
rear none
roof 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 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! :wink:

Hi.

13) Gun Carriers part 1

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

a) 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

To be continued in part 2…

Hi.

13) Gun Carriers part 2

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 wplaced 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 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: 1
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! :wink:

Hi.

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 anmmunition 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:

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 roaswheel 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.

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.

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!

Hi.

15) Engineer AFV part 1

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 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 quadratic 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

to becontinued in part 2…

Hi.

15) Engineer AFV part 2

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

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! :wink:

Hi.

16) Railroad AFV part 1

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

to be continued in part 2…

Hi.

16) Railroad AFV part 2

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! :wink:

Hi.

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 was 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 Aluminium-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! :wink:

Hi.

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


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 replaced 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 Vehicle should work as team with the Armored Lumberjack Ho-K.

Data:

unknown

Yours

tom! :wink:

Hi.

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! :wink:

Hi.

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! :wink:

Hi.

21) Infantry AFV:

IJA developed a small number of special afv for infantry use. These were mainly used to transport men and supply.

a) Type 98 Armored Transport So-Da:

With the introduction of the Type 97 Tankette Te-Ke a special version for armored ammunition transport was developed. The engine was moved to the right of the driver. The fighting and engine compartments were replaced by an open top cargo bay. It was possible to transport up to 1 t of cargo or 4-6 soldiers. The tank could be loaded and unloaded through a large vertical two hatch door on the rear. A towing bar was mounted for lighter weapons up to the Type 1 47 mm Rapid-fire Gun.

Data:

Vehicles built: unknown
crew: 2 men
capacity: 1 t of cargo or 4 – 6 soldiers
length: 3800 mm
width: 1900 mm
height: 1600 mm
weight: 5000 kg empty
armor strength: 6 – 12 mm
engine: 4-cylinder Diesel
power: 65 hp/2300 rpm
speed: 45 km/h on roads
range: 200 km
armament: none

b) Type 1 Armored Personnel Carrier Ho-Ki:

In the late 1930th the development of full tracked transport vehicles started. After several trials with different suspensions Hino Motors developed a version with a semi-Christie suspension consisting of four large road wheels, a rear driving wheel, a forward idle wheel and two return rollers. Driver and engine were placed in the bow. On the rear a large open top transport compartment for up to 14 men was mounted. Access was possible by a large two door hatch on the rear. There was also a towing bar but with a trailer or gun towed it was a problem to unload the soldiers quick.

The 6 mm armor was vertical with a slightly sloped bow armor. It was possible to mount a standard heavy MG on the driver´s compartment for defense. A 6-cylinder Diesel engine was used. Due to a low priority production did not start before early 1944. Several vehicles were sent to China and the Philippines but most of the limited serial production was issued to the 3rd Tank Division in Japan for homeland defense.

Data:

Vehicles built: at least 200
crew: 2-3 men
capacity: 2 t of cargo or 12 - 13 soldiers
length: 4780 mm
width: 2190 mm
height: 2580 mm
weight: 5500 kg empty
armor strength: 6 mm
engine: 6-cylinder Diesel
power: 134 hp/2000 rpm
speed: 42 km/h on roads
range: 300 km
armament: none, a Type 92 7,7 mm HMG could be mounted

c) Type 1 Armored Personnel Carrier Ho-Ha:

In 1941 IJA ordered Hino Motors to develop a fast half-tracked APC similar to the german SdKfz. 251. It should carry up to 12 soldiers or 2 t of cargo under armor protection against infantry small rounds at a maximum speed of 50km/h. The halftrack design should be taken as it was expected that fully tracked vehicles of that size wouldn´t be able to drive at the necessary speed.

The resulting vehicle had similarities with the SdKfz 251 but was a different design. The front axle wasn´t powered and should only be used to steer on harder ground. The rear suspension consisted of two pairs of large road wheels, a forward driving wheel, a rear idle wheel and a single return roller between the center road wheels. Both sides could be used for steering separately by using the reduction gears or the breaks.

A 6-cylinder Diesel engine was mounted in the bow. A crew compartment for driver and commander was mounted behind the engine. The rear 2/3 of the vehicle were a large storage room. The 6 mm armor was arranged sloped to the front and the sides with the lower bow and side armor negatively and the upper armor positively angled. The rear armor was vertical. A large two-door hatch opening to the sides allowed access to the storage compartment. The whole rear structure was open top but could be covered by a canvas. For close defense three LMG could be mounted on each side behind the crew compartment and on the rear.

Production did not start before 1944 with ca. 300 vehicles built. Most production vehicles were issued to homeland defense units. Only a few were sent to China and the Philippines with fewer reaching their targets due to the large air and sea superiority of the Allies. After the war some of the surviving vehicles were used for civil purposes but most were destroyed.

Vehicles built: ca. 300
crew: 2 -3 men
capacity: 2 t of cargo or 12 - 13 soldiers
length: 6100 mm
width: 2100 mm
height: 2510 mm
weight: 7200 kg empty
armor strength: 6 mm
engine: 6-cylinder Diesel
power: 134 hp/2000 rpm
speed: 51 km/h on roads
range: 300 km
armament: none, three LMG mounts were placed behind the crew compartment and the rear


d) Experimental Amphibious Landing Vehicle:

Amphibious wheeled vehicle with a lightly armored fighting compartment developed by Toyota. It was based on the Amphibious Truck Su-Ki. The boat-shaped hull made it possible to use the vehicle even in rougher sea. Details are unknown.

Data:

unknown

That´s the actual state of my research on this topic. Feel free to ask or to correct things I got wrong.

Yours

tom! :wink:

Hi.

Somewhat off topic but related:

Navy Armoured Fighting Vehicles part 1

The Imperial Japanese Navy used AFV since the First Shanghai Incident in 1932. First vehicles were domestic and foreign armoured cars like the Type Crossley Armoured Car or the Osaka Armoured Car. The first tank unit was raised in 1936 as part of the Tokubetsu Rikusentai = Special Naval Landing Forces (japanese Marines). It was equipped with standard Type 89 Medium Tanks. Later navy tank units were based on various pacific islands equipped with Type 95 Light Tanks, Type 97 Medium Tanks and Type 97 Medium Tanks KAI. IJN tanks used an anchor instead of a small yellow star as national emblem. Several units also painted the Rising Sun Flag (the navy war flag) on their tanks. IJA units only used the Hinomaru Flag (the army war flag) on captured tanks to mark them as own vehicles. After 1940 IJN developed several special tank and armoured vehicle types which are covered here.

a) Special Type 2 Motor Launch part 1:

After taking over the results of the army amphibious tank project in 1937 IJN start to think about how to use this kind of vehicles for amphibious operations of their Special Naval Landing Force (SNLF). Several studies were made regarding potential operational use, necessary features and possible tactics. With the decision to start a war in the Pacific in 1940 IJN increased the efforts and in early 1941 the decision was made to develop an amphibious tank. In cooperation with Army Technical Bureau and Mitsubishi such a vehicle should be built based on the Type 95 Light tank. Requirements were among others:

  • watertight construction
  • fully seaworthy even in heavy weather
  • fully welded
  • range afloat at least 100 km
  • speed afloat 10 km/h
  • floating devices removable from inside
  • armament consisting of a Type 98 37 mm Tank Gun and two Type 97 7,7 mm Tank MGs
  • easy to be build

The first tests with the incomplete prototype started in late 1941 at Lake Hamada, Shizuoka Prefecture. The vehicle was finished until early 1942. It consisted of the tank, two large detachable pontoons, a detachable conning tower and a detachable special air intake extension. All hatches openings and holes were made watertight by rubber seals or bulletproof glass. Crew consisted of driver, bow gunner, commander, gunner, ammunition supplier and mechanic. As IJN was not allowed to operate tanks the vehicle received the designation “Special Motor Launch” instead.

The vehicle was very different from the Type 95 Light Tank. Suspension and power transmission were similar but most parts were newly developed to cope with the weight. The rear idle wheel was relocated to the ground to increase ground contact. The springs and bell cranks were all mounted inside the vehicle to protect them from corrosion by sea water.

The armor scheme was completely different. Bow and rear armor were optimised for easy removal of the pontoons. All armor plates were flat and welded together. The lower bow armor consisted of two flat 12 mm armor plates with different negative angles. The upper part covered the tracks. Two clamps were mounted in the upper armor plate to fix the forward pontoon afloat. The upper bow armor was arranged sloped with both sides bent to the rear. A visor port for the driver was mounted on the (in driving direction) right side. In the center a third clamp for fixation of the pontoon was placed. On the left a standard MG mount was riveted to the armor plate. With the MG removed a detachable hemispherical cap covered the MG port watertight. Just before going ashore the cap was dropped off and the MG was mounted.


frontal view

The side armor was arranged vertical. Flotation chambers were placed above the tracks on each side which also gives additional protection by the spaced armor effect. There was no access hatch for driver and bow gunner. On each side a ventilation air intake for the fighting compartment was mounted on the top armor next to the rear part of the turret. Both were covered with a hatch. Above the driver the steering cable for the rudders is starting. Several guide pulleys leads the cable to the rear along the right upper edge of the fighting compartment.

The turret was a modified version of the turret from the Type 98 Light Tank. It was slightly conical with a large hole for optical equipment on each side of the gun mount. A large semicircular hatch on the turret with a two-part lid allowed access. Armament consisted of a Type 98 37 mm Tank Gun and a coaxial Type 97 7,7 mm Tank MG mounted slightly offset to the left. A semicircular handrail was welded on the rear turret to make entering the tank afloat easier. A removable steering mechanism for the propellers and rudders was inside the turret. Afloat the commander steered the tank from there. The gunner left the turret during that phase.

The top armor of the engine compartment was arranged sloped to the rear. The side armor was slightly sloped, too. The side parts next to the engine compartment were arranged sloped with a much lower angle to simplify slipping of the rear pontoon when removing it. The rear armor had a nearly vertical upper part and a negatively angled lower part. Clamps on the armor on the side of the engine compartment and on the upper rear armor fixed the rear pontoon afloat.

The engine was mounted lengthwise in the rear. There was no separating steel plate between fighting compartment and engine making it quite loud inside the tank during movements. Three hatches in the rear top armor allowed access to the rear fighting compartment and the engine. The center hatch was the largest. It had a large air intake covered with a grid. The detachable air intake extension could be mounted on this grid using clamps and hooks. A rubber band on the armor plate made the connection watertight. The mesh-covered muffler was placed on the right side, the tail pipe was raised.

The ammunition supplier and the mechanic had their seats between turret and engine. The ammunition supplier had to help the commander by giving him the ammunition loaded inside the vehicle. He also moved MG ammunition from the transport racks to the bow gunner and gunner. The mechanic had to watch and maintain the complex machinery especially during operations afloat. During operations on land he was not really needed (repairs could be done faster by the maintenance units) and so not inside the tank most of the time.

[
improved forward pontoon

The forward pontoon had a u-shape and was designed streamlined for an excellent driving quality. He had three flotation chambers with a total volume of 6,2 m³. The pontoon could be lifted by a collapsible jib boom (part of the equipment) over three hooks on the upper edge and two short handling rods on the lower part. With the pontoon attached the driver´s visor port was completely covered. A small recess allowed mounting the MG.

The rear pontoon was also u-shaped with the rear edges rounded. It was had three flotation chambers but only with a volume of 2,9 m³. The rudders were mounted under the pontoon on long axles which reached through the whole pontoon to the steering mechanism on top. Six hooks are mounted on the upper edge and two handling rods on the lower part for handling the pontoon with a jib boom.

Afloat the tank was operated from a small detachable conning tower mounted on the turret which could be easily detached. This was necessary as the view from inside the turret was too bad for navigation on the sea. The tower was conical with three visor ports next to each other in the forward part and three more mounted in each side and the rear. On top was a small access hatch. On the ocean the commander steered the rudders from inside the tower.

To prevent spray from the waves to get inside the engine a conical rectangular air intake with a wider cap could be mounted on the engine compartment. This was necessary in bad weather or heavier sea.

To be continued in part 2…

Hi.

Navy Armored Fighting Vehicles part 2

a)Special Type 2 Motor Launch part 2:


rear pontoon

The pontoons, the conning tower and the air intake extension were welded using 3,2 mm thick face-hardened armor plates. It was possible to transport both pontoons with a single Type 94 6X4 Truck. All parts necessary to get the tank ready for operation could be mounted by the crew within 15 minutes with the equipment of the tank.

Afloat two large screws next to the tracks moved the tank. The driving shafts were connected with the engine over a power dispensing devise which separates the two types of propulsion. This device was also responsible for sending power to the bilge pumps. The rudders were mounted on the rear pontoon.

The concept worked very well and so in mid 1942 the decision was made to start a serial production immediately. Official designation was “Special Type 2 Motor Launch”. It seems that the popular short designation “Ka-Mi” wasn´t adopted officially but it was used by the units operating the vehicles. 300 vehicles were ordered. The first unit using this tank was formed in late 1942. There are few US reports of early version Type 2 armed with the Type 94 37 mm Tank Gun but there was no japanese source yet.

After the first exercises some changes were demanded by the soldiers. So a radio was added, the antenna base was welded on the rear right of the turret. The forward pontoon was remodeled to improve detaching. Therefore it was cut along the center line making it two-piece. The recess for the bow MG was widened to make the driver´s visor port accessible. The clamp in the upper bow armor was now surplus. A handrail was added to the pontoon. Other changes were made inside the tank to simplify handling. Most important was the installation of an onboard communication system with headphones to compensate the engine noise. The changes were adopted officially in summer 1943.

Only 184 vehicles were produced by Mitsubishi until surrender due to raw material shortages and a change in IJN strategy. They were issued to independent tank companies of the SNLF. Several units fought against US invasion forces in 1944 and 1945. Most spectacular was the attack of the 101st SNLF which swam from Luzon via Samar to Leyte during the US Invasion in late 1944. Due to the weak gun the success was limited. Nevertheless the US Army and Navy was impressed by the good seaworthiness which was far superiour to any other contemporary amphibious tank in the world. It was even possible to carry the tanks with submarines and launch them shortly below the surface.


rear view

In western literature the first production version is sometimes designated “Type 1 Ka-Mi” or “Type 1 Ka-Sha” which is not correct. There was no change in the official designation.

There are still several Type 2 Ka-Mi rusting on different pacific islands. Only few are on display in museums. A vehicle with both pontoons and the air intake extension can be seen at Kubinka Tank Museum near Moscow.

Data

vehicles built: 184
battle weight: 9,15 (metric) t, 12,5 t with floating equipment
crew: 5-6 men
length: 4800 mm, 7420 mm with pontoons
width: 2800 mm
height: 2300 mm
track width: 305 mm
engine: Mitsubishi A6120VD in-line 6-cylinder air-cooled Diesel engine
power: 115 hp at 1800 rpm
maximum speed: 37 km/h on roads, 9,5 km/h afloat
range: 320 km on roads 140 km afloat
transmisson: 8 forward, 2 reverse
armament: 1 X Type 98 37 mm Tank Gun , 2 X Type 97 7,7 mm Tank MG
Ammunition capacitiy: 132 37 mm grenades, 3900 MG shots

armor strength
turret front 12 mm @ 85 °
sides 12 mm @ 85 °
rear 12 mm @ 85 °
roof 6 mm @ 0 °
superstructure front 12 mm
sides 6 + 6 mm @ 90 °
rear 12 mm
top 6 mm

b) Special Type 3 Motor Launch:

After introduction of the Type 2 Ka-Mi SNLF demanded a similar vehicle with more armour and a 47 mm gun. The development of a successor was started in early 1943. Most data were lost after surrender. So many details are unknown.

Development was done in cooperation with Mitsubishi. To speed up the process many parts of the Type 1 Chi-He were used including the turret, the engine, suspension elements and parts of the transmission and steereing. Other elements were modified from the predecessor like the pontoons, steering and propulsion afloat and internal structure. But it was not developed from the Type 1 Chi-He as stated in many sources.

The hull was huge and bulky. Bow, side and rear armor were almost vertical making it easy to penetrate it. Only the upper front and side armor was arranged sloped. There were four access hatches to the flotation chambers in each side armor. Two clamps each in the bow and upper bow armor fixed the frontal pontoon. Driver´s visor port and bow MG were arranged as in the Type 2 Ka-Mi. The turret was placed in the center line. There were two pairs of ventilation hatches on the sides of the top armor, one between driver and turret and one next to the turret overhang. The cable for operating the rudders started on the right side in front of the turret. Number and location of the access hatches to the fighting and engine compartment are unknown. The air intake extention was mounted at the rear end of the engine compartment. So it can be assumed that the main engine access hatch was there, too. There was an exhaust pipe with muffler and raised tail pipe on each side of the vehicle´s rear top armor. Four clamps on the rear armor fixed the rear pontoon.

The suspension consisted of four pairs of roadwheels. Two pairs each were connected with bell cranks to a large vertical coil spring covered by a semicircular armor plate. The rear idle wheel protruded the vehicle completely. The frontal driving sprocket and four return rollers completed the suspension. All parts were mounted outside the vehicle.

Both pontoons were quite similar to the pontoons of the predecessor but they were larger to cope with the weight. The rear pontoon did not enclose the vehicle rear. It was completely behind the tank. A similar conning tower for the commander´s cupola and a similar air intake extension completetd the equipment for seaworthiness.

Only the prototype and 19 pre-series vehicles were built in late 1944. It is unknown if the short designation “Ka-Chi” was adopted officially. The vehicles were only used for exercises. Some internet sources claim that there was a successful test launch from a submerged submarine from a depth of 100 m but I found no more reliable sources yet. There is no known survivor today.

The whole vehicle was far too large for the chosen armament and the armor scheme and strength would have made it an easy to destroy target.

Data

vehicles built: 20
battle weight: 28,25 (metric) t with floating equipment
crew: 5-6 men
length: 10300 mm with pontoons
width: 3000 mm
height: 3820 mm
engine: Mitsubishi Type 100 V-type 12-cylinder air-cooled Diesel engine
power: 240 hp at 2000 rpm
maximum speed: 32 km/h on roads, 10,5 km/h afloat
range: 320 km on roads 140 km afloat
transmisson: 8 forward, 2 reverse
armament: 1 X Type 1 47 mm Tank Gun , 2 X Type 97 7,7 mm Tank MG

to be continued in part 3…

Hi.

Navy Armored Fighting Vehicles part 3

c) Special Type 4 Motor Launch:

After the Battle of Wake IJN decided to make a larger survey about the causes of the quite large losses. One main cause found was that the landing craft used were open to the top exposing the passengers to enemy small arm fire and especially splinters. In addition the armor was relatively weak making it easy to penetrate the sides and the bow with heavier weapons. This problem became urgent again during the 1942 Solomon Island campaigns. There landing crafts were often attacked by aircraft which shot into the cargo bay from above. As result the decision was made to develop a better protected landing craft for these kind of operations. Requirements were among others:

  • easy to unload and load for transport ships
  • usable on land and in the water
  • closed cargo compartment
  • armed with one or two Type 93 13,2 mm Machine Cannons for close defence

In 1943 the US presence was increased especially in the south and central pacific. This lead to increasing losses among transport and supply shippings because of submarines and long-range aircraft. Especially forward garrisons on smaller island were sometimes cut off from supply. So the landing craft should additionally be able to be transported and launched from submarines.

A prototype was finished in late 1943 at Kure Naval Yard. Operational tests were finished in March 1944. Crew consisted of driver, navigator, two gunners and a mechanic. The vehicle had a boat-shaped armored hull with a maximum armor strength of 10 mm. Afloat the landing craft was powered by two propellers in the rear. Rudders were behind them for steering. For movenments on land a track suspension was added. The suspension was similar to the Type 98 Light Tank Ke-Ni. It consisted of four pairs of roadwheels connected with bogies. Each two pairs were connected by bell cranks with large horizontal coil springs. These elements were placed inside the vehicle for protection against corrosion by seawater. A forward driving sprocket, five return rollers and a rear idle wheel completed suspension.

The whole vehicle was covered by an armored deck. Internal chambers on the bow and rear delivered additional buoyancy for stabilty. Crew and engine compartment was in the forward half. A driver and a navigator operated the landing craft from an armored cabin with two visor ports on the bow. The rudders were operated over a cable mechanism similar to the Special Type 2 Motor Launch. During the final approach to the shore the driver could change to a steering position on the deck behind the cabin. There he was protected by armor plates from the front and the sides. The rear was open for a better overview. A visor port was placed in the frontal plate. A Type 93 13,2 mm AA-Machine Cannon could be mounted on a pivot on each side of the steering position on deck.

The vehicle was powered by the Mitsubishi A 6120 1 in-line 6-cylinder Diesel engine, a modified version of the engine of theType 97 Medium Tank. The air intakes on deck were made water-tight with float valves. A long exhaust pipe lead to the rear mounted muffler with raised tail pipe. A cargo compartment was placed behind the engine compartment. Maximum payload was 4 t or up to 40 men (some of them on deck). It was possible to carry larger loads on deck but vehicles could not be carried. There were three watertight access hatches on the crew compartment and three more on the cargo compartment. Several hooks around the deck allowed easy loading and unloading from ships

During tests the vehicle was easy to steer but slow. Nevertheless the design was accepted under the designation “Special Type 4 Motor Launch”.It is unclear if the short designation “Ka-Tsu” was introduced officially.

In January and February 1944 US forces captured the central pacific atolls of Eniwetok, Kwajalein and Majuro. During the following months US-Navy expanded the already built japanese air and naval bases to a a large forward base for future operations against Truk and the Marianas (Saipan, Tinian, Guam). Japanese submarines and long-range reconnaissance aircraft delivered good reports about these works. So in April 1944 IJN started to plan a massive attack on these bases (Operation Yu-Go). Part of these plans was to launch special attack units using torpedo vehicles from submarines to attack anchorages. For this operation the vehicles should be used. This made several modifications necessary.

The exhaust pipes and the steering mechanism for the rudders were relocated below the deck. On each side a mount for a modified Type 91 Model 3 450 mm aircraft torpedo was welded on the deck above the fighting compartment (Many western sources claim that the torpedoes were Type 93 610 mm Long Lance but almost all japanese sources say Tpe 91 Model 3). A simple aiming device was mounted in the driver´s cabin. Special hooks to carry the vehicle with submarines were also added. To mount the torpedoes the machine cannons had to be removed. During the first trials the crew had problems to keep the vehicle watertight submerged. The air intakes finally had to be sealed with special coverages to prevent the engines from flooding but it took some 20 minutes to remove them and to make the vehicles ready to start. During this time the submarine had to stay at the surface. A submerged start as planned was not possible. Nevertheless IJN decided to introduce the vehicle with these changes. Production numbers are unknown but at least 50 vehicles were built.

Operation Yu-Go was cancelled in mid 1944 due to the fast US advance to the Marianas. The operating soldiers disliked the slow speed afloat but they had to use the vehicles because there was nothing similar avaliable. Crew training continued and until late 1944 800 soldiers were trained on these vehicles. In late 1944 operations against US ships at Luzon were planned but cancelled after a tanker destined for fuel supply was sunk during a convoy mission.

Some sources claim that the unit was used in 1945 to resupply cut-off pacific island garrisons. The plans for homeland defence included suicide torpedo attacks of the Special Type 4 Motor Launches on the invasion fleets.


2 vehicles equipped with torpedoes carried by the B2-class submarine I-41

Most vehicles were scrapped postwar but at least one is on display at WWII and Korea LVT Museum, Camp Del Mar, Marine Corps Base Camp Pendleton, California, USA

Data

vehicles built: 50 or more
battle weight: 16 (metric) t
crew: 5 men
maximum armor: 10 mm
length: 11000 mm with pontoons
width: 3300 mm
height: 2250 mm to deck, 4050 mm maximum
engine: Mitsubishi A 6120 1 in-line 6-cylinder air-cooled Diesel engine
power: 120 hp at 2000 rpm
maximum speed: 20 km/h on roads, 8 km/h afloat
range: 300 km afloat
armament: 2 X Type 93 13,2 mm Machine Cannon or 2 X Type 91 Model 3 450 mm Torpedo

to be continued in part 4…

Hi.

Navy Armored Fighting Vehicles part 4

d) Special Type 5 Motor Launch:

no picture, sorry

There are only few informations about this vehicle avaliable. It is even not sure that the prototype was finished before surrender.

Upon the avaliable drawings (which differ largely in details) it can be assumed that the tank was a try to remodel the Special Type 4 Motor Launch to make it less vulnerable against enemy fire. Size and shape are similar, most known data also fit for both vehicles. The most significant changes are a far better bullet deflecting armor scheme, a change in armament and different pontoons.

The upper bow armor was now sloped with a lower angle. The lower part was still negatively sloped but with a shallower angle. The superstructure armor wasn´t changed on front and sides. The rear armor was now similar to the Special Type 2 Motor Launch.

The Type 1 47 mm Tank Gun was now mounted on the position of the bow MG. The MG was replaced to the right between gun and driver´s visor port. In the turret a modified Type 96 25 mm Machine Cannon replaced the gun.

The frontal pontoon was now flatter to allow using the bow armament during landing. The rear pontoon was shorter and had the shape of the rear pontoon of the Special Type 2 Motor Launch


Scale model, details are surely different to the historical vehicle

Due to an error in the book “Tanks of the World 1915-1945” from Peter Chamberlain and Chris Ellis many internet sources show a picture of the Special Type 2 Motor Launch without floating equipment as a picture of this tank. This is definitely wrong. There is no known picture of the Special Type 5 Motor Launch.

Data

vehicles built: 1
battle weight: 29,1 (metric) t
crew: 5-7 men
maximum armour: 50 mm
length: 10800 mm with pontoons
width: 3000 mm
height: 3380 mm
engine: Mitsubishi Type 100 V-type 12-cylinder air-cooled Diesel engine
power: 240 hp at 2000 rpm
armament: 1 X Type 1 47 mm Tank Gun, 1 X Type 96 25 mm Machine Cannon, 2 X Type 97 7,7 mm Tank MG

e) Short Barrel 120mm Gun Tank:

In late 1944 the SNLF demanded a gun tank similar to the IJA Type 2 Gun Tank Ho-I but with a larger gun for close support. So the decision was made to upgun the Type 97 Medium Tank KAI with the short 12 cm gun developed in 1942/43 for close defence of transport ships.

The hull of the tank was not changed. The gun mount was replaced by a massive mount with a large recoil mechanism. There were several recoil cylinders mounted around the barrel and covered with a round armour for protection. This recoil mechanism was still not able to cope with the recoil forces and so a flat muzzle break had to be added, too.

The gun was developed as high-angle multi purpose gun. It should provide close-range fire against aircraft , submarines and small attack boats. Due to the short barrel it was almost impossible to hit moving targets so only barrage fire was made. Data for the gun are:

  • caliber: 120 mm
  • gun length: 1510 mm
  • bore length: 1440 mm (L/12)
  • rifling length: 1127 mm
  • grooves: 24 (1.0 mm x 11.78 mm)
  • lands: 3,93 mm
  • twist: Increasing RH 1 in 30 to 1 in 13
  • weight: 2950 kg with mount
  • chamber volume: 3 dm³
  • muzzle velocity: 290 m/sec
  • rate of fire: up to 15, 10 for continuous fire
  • ammunition: HE, Incendary, Chemical, Anti-submarine
  • grenade weight: HE 11,8 kg with a warhead of 2,5 kg and a propellant charge of 0,49 kg
  • fuzes: time, impact, anti-submarine (time and/or preasure)
  • maximum range: 5300 m
  • maximum ceiling: 3100 m

Maximum range was reduced due to the limited elevation of the gun mount. Due to the screw-type breech of the new gun the already low space inside the turret was reduced. In addition the ammunition was heavy.

Further details are unknown.

An unknown number of Chi- HA KAI were modified this way in 1945. After surrender US units found at least 4 vehicles at Sasebo SNLF base and 10 more at Yokosuka SNLF base. All were scraped postwar.

Data
as Type 97 Medium Tank Chi-Ha KAI except:

vehicles built: at least 14
armament: 1 X Navy Short 12 cm Gun , 1 X Type 97 7,7 mm Tank MG

[f) Long Barrel 120 mm Gun Tank:

[
only known picture

Informations on this vehicle are rare. After surrender US forces found at least one vehicle at Yokosuka Naval Yard. It is unknown if it was a local conversion or an official development.

A Type Taisho 10 120 mm gun was mounted on the hull of a Type 97 Medium Tank. The turret was removed and the hole closed by steel plates. Additional steel plates were welded on each side of the fighting compartment to create a platform for the gun crew.

Data of the gun are:

  • caliber: 120 mm
  • gun length: 5600 mm mm
  • bore length: 5400 mm (L/45)
  • rifling length: 4649 mm
  • grooves: 34 (1.45mm x 6.688 mm)
  • lands: 4,4 mm
  • twist: uniform RH 1 in 28
  • weight: 218 kg without pivot
  • chamber volume: 10,774 dm³
  • muzzle velocity: HE 830 m/sec Illuminating 700 m/sec, anti-submarine 250 m/sec
  • rate of fire: up to 11 per minute, 7 for continuous fire
  • ammunition: HE, AP , Incendary Shrapnel (AA), Illuminating, Anti-submarine
  • grenade weight: HE 34 kg with a warhead of 1,9 kg and a propellant charge of 5,5 kg
  • fuzes: time, impact, anti-submarine (time and/or preasure)
  • maximum range: 16000 m
  • maximum ceiling: 10000 m

There are no further infos. Due to the gun weight and dimensions it can be assumed that the vehicle was top-heavy making it a quite unstable firing platform.

Data:

unknown

Yours

tom! :wink: