Type 4 40 cm rocket launcher

The Type 4 40 cm rocket (四式四〇糎噴進, Yonshiki yonjū-senchi funshinhō) was a 400 mm (16 in) rocket used by the Imperial Japanese Army in the final stages of World War II.

Type 4 40 cm rocket launcher
Type 4 40 cm rocket
Type	Rocket artillery
Place of origin	Empire of Japan
Service history
In service	1943–1945
Used by	Imperial Japanese Army
Wars	World War II
Production history
Designed	1944[1]
Produced	1945[2]
No. built	1,700 wooden launchers during 1945, less than 200 rockets starting May 1945 [3]
Specifications
Mass	220 kilograms (490 lb)
Barrel length	3.22 metres (10 ft 7 in)
Shell	508 kilograms (1,120 lb)
Caliber	400 mm (16 in)
Elevation	40° to +65°
Muzzle velocity	220 m/s (720 ft/s)
Maximum firing range	3,700 metres (4,000 yd)

Development and design

The Type 4 40cm rocket was developed in the final stages of World War II by the Imperial Japanese Army Technical Bureau, as a relatively low-cost, easy to produce weapon, which had an advantage of greater accuracy over conventional mortars in that it fired a spin-stabilized projectile. Due to its ease of construction, it was produced in limited numbers and distributed to hidden arsenals for use as last-ditch weapons during the projected Allied invasion of the Japanese home islands. Unlike the Japanese Type 4 20cm rocket mortar, the Type 4 40cm rocket did not see action and stocks were confined to the mainland. ^[4]

The Type 4 40cm rocket was restricted to launch via standardized fixed wooden troughs which were largely constructed by Japanese Army garrison toops, and not steel tubes like the Type 4 20cm rocket mortar. During 1945 construction of the fixed wooden launchers outpaced actual production of the Type 4 40cm rocket. Range of the Type 4 40cm rocket was controlled via variable bleeding of the propellant gases. ^{[5] [6] [7]}