Type 4 40 cm Rocket Launcher

• Name — Type 4 40 cm rocket launcher • Origin — Empire of Japan • Type — Rocket artillery • Is Ranged — yes • Is Artillery — yes • Service — 1943–1945 • Used By — Imperial Japanese Army • Wars — World War II • Design Date — 1944 • Production Date — 1945 • Number — 1,700 wooden launchers during 1945, less than 200 rockets starting May 1945 • Weight — 220 kg • Part Length — 3.22 m • Cartridge — 508 kg • Caliber — 400 mm • Velocity — 220 m/s • Max Range — 3700 m • Elevation — 40° to +65°

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. The Type 4 40cm rocket was restricted to launch via standardized fixed wooden troughs which were largely constructed by Japanese Army garrison troops, 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.