The Imperial Japanese Navy developed a number of spin-stabilized rockets during World War II, but only this one ever saw service use. These went to sea in launchers containing 28 rockets with six launchers on most carriers. The rocket had an incendiary shrapnel warhead, somewhat similar in design to the "Sankaidan" Type 3 projectile used for guns, and had a time fuze set to explode the warhead at either 1,000 or 1,500 meters (1,100 or 1,640 yards).

Rockets had six 0.455 in (1.15 cm) diameter nozzles with 25 degree inclination and 10 degree divergence.

Gun Characteristics

Designation 12 cm (4.7 in) AA Rocket
Ship Class Used On Carriers 1944-45
Date Of Design 1943
Date In Service 1944
Gun Weight N/A
Gun Length oa Rails: 42.65 in (1.083 m)
Bore Length N/A
Number Of Grooves N/A
Length Of Rifling N/A
Chamber Volume N/A
Rate Of Fire Manual: Fired in single pairs
Automatic: 14 pairs in 10 seconds


Type Rocket
Projectile Types and Weights 49.6 lbs. (22.5 kg)
Bursting Charge Incendiary Shrapnel
Projectile Length 28.74 in (73.0 cm)
Propellant Charge 7.5 lbs. (3.4 kg)
Maximum Velocity 656 fps (200 mps)
Working Pressure 2,790 lbs./in2 (196 kg/cm2)
Approximate Barrel Life N/A
Ammunition stowage per gun N/A

Reloading was by hand.


Elevation Distance
Range with time fuzes 1,100 or 1,640 yards (1,000 or 1,500 m) 1 2
Maximum Range
5,250 yards (4,800 m)
Maximium Height at 80 degrees about 7,545 feet (2,300 m)
  • ^Time fuzes were set to either 5.5 seconds or 8.5 seconds.
  • ^Propellant burnt for 1.6 seconds.

Mount/Turret Data

Designation 28-rocket launchers
   Most Carriers (6) and Shinano (12) 1a: Type 5 (1945) 2a
Weight 3,521 lbs. (1,597 kg)
Elevation +5 / +80 degrees
Elevation Rate 18 degees per second
Train N/A
Train Rate 22 degrees per second
  • ^These launchers were not installed on Shinano before her loss.
  • ^These mountings were adapted from the 25 mm AA triple gun mounting and could be controlled by Ward-Leonard RPC or by two men in protected cabs. The launcher resembled a large box which consisted of four rows of seven rockets each.
  • This rocket or a similar one with an HE warhead was also carried by some explosive motor boats fitted with a simple launching trough.

Additional Pictures


"Naval Weapons of World War Two" by John Campbell
"The 12 cm Multiple Rocket Launcher of the Imperial Japanese Navy" article by Hans Lengerer and Tomoko Rehm-Takahara in "Warship Volume IX"
US Naval Technical Mission to Japan report O-19: Japanese Projectiles General Types
US Naval Technical Mission to Japan report O-50 (N): Japanese Shipboard Rocket Launchers

Page History

04 July 2006 - Benchmark
27 May 2012 - Updated to latest template
27 August 2018 - Converted to HTML 5 format and reorganized notes
20 January 2019 - Corrected typographical error and added arrangement sketch