In 1943 the decision was made to develop a tank gun based on the type 4 75 mm aa-gun which became operational in early 1944.
For this gun a special gun carrier should also be developed, based on the chassis of a newly designed full-tracked heavy transport vehicle (Chi-So) using a remodelled chassis of the type 4 experimental tank Chi-To.
A prototype was built in April, 1944. The engine of this vehicle was placed in the bow. The engine room and the driver cabin for the driver and the wireless operator were armoured with welded 12 mm thick armour plates.
Behind the driver´s cabin the type 4 75 mm tank gun should be placed on a special pivot mount. A 12 mm gun shield should covered the 5-men gun crew from infantry ap-rounds, but only from the front. The chassis was tested in summer 1944 showing a large vulnerability of the gun crew regarding infantry fire from the sides. This was solved by installing two aditional side armour plates on both sides of the gun mount.
The gun prototype was also tested in Summer 1944 showing multiple problems with stability and recoil mechanism making a major redesign necessary. This redesign was done in early 1945. Now there were additional problems with the gun mounts of the type 4 tanks but as the guns on the Na-To were mounted on a pivot there was no problem for the use on the tank hunter.
The completed vehicles were tested in spring 1945 showing a good mobility and cross-county ability. The gun was able to penetrate the US medium M4 on ranges over 1000 m making the vehicle a dangerous weapon. In May, 1945, a couple of type 5 75 mm tank hunter Na-To were sent to northern China for battlefield tests. It is possible that these vehicles were destroyed during the soviet attack in August, 1945 but all documents egarding these late-war developments were destroyed after the japanese surrender.
That Type 5 is deadly!! It getting up to German power
manufacturer: Osaka Rikugun Zoheisho (Osaka Army Arsenal)
number of vehicles built: 2 or more??
total weight: 15 t
crew: 7 men
maximum armour strength: 12 mm
length: 5800 mm
width: 2400 mm
height: 2750 mm
engine: Mitsubishi 8 cylinder gasoline engine
power: 165 hp/2000 rpm
maximum speed: 40 km/h
power-weight-ratio: 11 hp/t
armament: 1 X Typ 5 75 mm gun
armour max: 12mm
here's some pics
the first is it on tests
however, does anyone have any info or pictures of the Chi-So
