11) Heavy Tanks a) Experimental Type 91 Heavy Tank: After finishing the tests with the Experimental Tank No. 1 Army Technical Bureau decided to continue development of this design. Goal was to meet the original requirements and to implement new design ideas. Development started in March 1928 at Osaka Army Arsenal using the Experimental Tank No.1 as test vehicle. First changes were made regarding the suspension. The general scheme was not changed but minor improvements were added. Two of the single roadwheels were removed and the remaining was slightly enlarged. The number of return rollers was increased by 2 (one forward and one in the rear) and they were placed in-line removing the track buckling. The suspension armor was simplified and the upper part was arranged sloped to improve mud removal. The weight was reduced significantly. The engine was modified by using aluminum for several parts increasing the power while reducing weight. Power transmission was also improved. This lead to a maximum speed of 25 km/h. The exhaust pipe was placed inside the tank and the muffler was covered with a mesh wire netting against small rocks and debris. First tests with modified suspension and the new main turret The armor scheme of the superstructure wasn´t changed too much but vulnerable parts received a strength of 20 mm instead of 17 mm and more sloped parts were used. A new turret with a smaller commander´s cupola was developed with a MG port in the 7 o´clock position. Armament was changed to a Type 90 57 mm Tank Gun. Continuous tests were made and every change was tested until it worked. Final weight was 16t as required for the Experimental Tank No. 1. In April 1930 the resulting vehicle was again showed to IJA High Command under the designation "Experimental Type 91 Heavy Tank" with mild steel armor plates. They were very pleased with the mobility but also demanded several changes: - the main armament was found too weak for such a heavy vehicle - the armor strength was found too weak for future fightings - a stronger engine should be used Development of the Type 91 Heavy tank was ceased in February 1932. Data: vehicles built: 1 as continuous development of the Experimental Tank No. 1 battle weight: 16 (metric) t crew: 5 men armor: up to 20 mm length: 6300 mm width: 2470 mm height: 2570 mm ground clearance: 400 mm track width: 350 mm trench crossing capability: 3000 mm climbing capability: 43° maximum vertical obstacle: 1000 mm engine: modified BMW 6-cylinder in-line gasoline aircraft engine power: 224 hp maximum speed: 25 km/h on roads transmission: 6 forward, 2 reverse armament: 1 X Type 90 57 mm Tank Gun , 1 X Type Taisho 3 6,5 mm MG in the main turret, 2 X Type Taisho 3 6,5 mm MG in separate turrets b) Type 95 Heavy Tank: The development of a successor of the Experimental Type 91 Heavy Tank started in December 1932 at Osaka Army Arsenal. The changes demanded lead to several reconstruction works. Additionally several new developments had to be started. The suspension was changed completely to the system used on the Type 89 Medium Tank. It consisted of a see-saw type suspension using two pairs of 4 roadwheels connected with a bar and a single frontal roadwheel for increased climbing abilities. The driving sprocket was placed in the rear. A frontal idle wheel and four return rollers completed it. The external suspension armor sheme was changed to the Type 89 late production standard. The superstructure was slightly remodeled raising it and increasing the length of the upper slope of the side armor. Maximum armor was now 35 mm. The forward turret was exchanged with a larger cylindrical turret housing a Type 94 37 mm Tank Gun to increase at-power of the vehicle. The main turret armament was changed to a Type 94 70 mm Tank Gun. The commander´s cupola was replaced by a flatter one with a two-door access hatch. Both remaining Type 3 MGs were replaced by Type 91 6,5 mm Tank MGs. The engine was remodeled, too. The prototype was completed in September 1934. It had a combat weight of 26 t and the 290 hp engine only allowed a speed of 22 km/h. In addition the vehicle was now too large to be transported on narrow mountain railroads. Nevertheless 3 more vehicles with face-hardened armor plates instead of the mild steel plates used on the prototype were built at Osaka Army Arsenal prior to the official presentation in mid 1935. IJA officials were not pleased with this tank: Type 95 Heavy Tank on display at Yasukuni Shrine - the speed was found to low and the size too large - use of a gasoline engine - the armor strength was again considered too weak against contemporary tanks. - in 1935 IJA tank doctrine does not need a heavy breakthrough tank as the main enemy was now considered China not the Soviet Union - the military budget expected after 1935 did not allow the introduction of such an expensive vehicle Therefore the decision was made to discontinue the development of a multi-turret tank design. One of the prototypes was handed over to Chiba Tank School for basic crew training, two were used for the development of heavy SPGs at Osaka Army Arsenal and the last became exhibit at Yasukuni Shrine in Tokyo. None survived the war. Data: vehicles built: 1 as continuous development of the Experimental Type 91 Heavy Tank + 3 battle weight: 26 (metric) t crew: 5 men length: 6470 mm width: 2700 mm height: 2900 mm ground clearance: 510 mm track width: 480 mm ground contact length: 4400 mm trench crossing capability: 3000 mm climbing capability: 43° maximum vertical obstacle: 1100 mm fording: 1100 mm engine: remodeled BMW 6-cylinder in-line gasoline engine power: 290 hp at 1600 rpm maximum speed: 22 km/h on roads fuel capacity: 400 l lubricant oil capacity: 40 l range: 110 km on roads transmission: 6 forward, 2 reverse power/weight ratio: 11,15 hp/t armament: 1 X Type 94 70 mm Tank Gun and 1 X Type 91 6,5 mm Tank MG in the main turret, 1 x Type 94 37 mm Tank Gun in the forward turret, 1 X Type 91 6,5 mm Tank MG in the rear turret ammunition capacity: 100 70 mm grenades, 250 37 mm grenades, 2940 MG shots armor strength turret front 30 mm @ 80 °[/td] sides 25 mm @ 90 ° rear 25 mm @ 90 ° top 16 mm @ 0 ° superstructure fron 35 mm sides 30 mm rear 25 mm top10 mm° suspension front 35 mm sides unknown + 6 mm external rear 25 mm Yours tom!