Type 10 and Type 3 rocket boosters

The Type 10 and Type 3 rocket boosters were rocket artillery systems used by garrison troops of the Imperial Japanese Navy during the late stages of World War II in defense of island bases in the Pacific.

Design
Instead of being a conventional piece of rocket artillery with motor and warhead enclosed within a body both types were detachable solid-propellant boosters that could be attached to a 56-63 kg Type 97 No.6 Land Bomb or Type 99 No.6 Ordinary Bomb. The bombs were launched from single wooden or metal inclined V-shaped troughs. These troughs could either be laid against earthen embankments or mounted on bipod or monopod launch frames. Elevation for the Type 10 could be varied by adjusting the guide wires on the base between +30° and +50°.

The rocket boosters consisted of a nose cone, propellant chamber, butt plate, tail fins, and a single venturi. The propellant chamber held three sticks of solid-propellant and was closed at the front by a nose cap. In the center of the nose cap, there was a socket for a blasting cap that was electrically ignited by an umbilical cord attached to the booster. The bombs and the booster were placed at the end of the trough and a wooden spacer was placed between the booster and the bomb. After a few seconds, the booster burnt out and dropped away while the bomb continued on its course. The Type 10's range was limited to 1300 yd. There was also a slightly longer rocket booster, the Type 3, that had a range up to 2000 yd and accuracy for both was poor. They were not weapons that could be fired at a specific target but were instead fired towards a target. Due to its limited range, the launchers were vulnerable to counter-battery fire and their poor accuracy made them more useful in siege operations than in defense.

Bombs
Since two different types of bombs and boosters were used the overall weight should be considered as approximate because the weight of each bomb without its tail cone is not known. Both the Type 97 No.6 Land Bomb or the Type 99 No.6 Ordinary Bomb could be used.