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.
== 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. 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.
Notes
== References == Bishop, Chris (eds) The Encyclopedia of Weapons of World War II. Barnes & Nobel. 1998. ISBN 0-7607-1022-8 Chamberlain, Peter and Gander, Terry. Heavy Field Artillery. Macdonald and Jane's (1975). ISBN 0-356-08215-6 McLean, Donald B. Japanese Artillery; Weapons and Tactics. Wickenburg, Ariz.: Normount Technical Publications 1973. ISBN 0-87947-157-3. US Department of War, TM 30-480, Handbook on Japanese Military Forces, Louisiana State University Press, 1994. ISBN 0-8071-2013-8
== External links == Type 4 on Taki's Imperial Japanese Army page
