Type 4 Incendiary Rocket (RoSa)

The Roketto Yon-shiki Shō-san-dan (ロケット四式焼霰弾, "type 4 incendiary rocket"), sometimes just RoSa-dan (ロサ弾, "incendiary rocket", abbreviation of the name) where anti-aircraft rockets used by the Imperial Japanese Navy during the World War II, combining incendiary shrapnel elements.

A 28 tubes rocket launcher

This rocket was deployed on the 12 Senchi 28 Rensō Funshinhō (十二糎二八連装噴進砲, "12 cm, 28 tubes rocket launcher"), a specially built rocket launcher, and equipped on certain Japanese aircraft carriers and battleships.

The rocket is designated with the English borrowing "rocketto", but stays more commonly classified as a "shell" (弾, "dan"), borrowing partially the technology used by the Type 3 anti-aircraft shell "San Shiki".

The rockets were intended to put up a barrage of flame, by being notably equipped on a 28 rack rocket-launcher, through which any aircraft attempting to attack would have to navigate. However, much like the sanshiki shells, these rockets were not very effective, lacking in effect radius among other things.

Specifications

Diagram of the connections between the launcher and the type 94 fire control system.

Section of a RoSa rocket.

These rockets were 12 cm (4.7 in) in diameter for 73 cm (29 in) long, and weighed 47 kg (104 lb). Similar to the "San Shiki", these rockets were made:

• 24 incendiary charges, that, once the rocket has exploded, would ignite and form long flames,
• Two explosive charges of 0.5 kg (1.1 lb), used to create a dispersion cone of 40 ° and 30 m (98 ft) in diameter, to create the barrier wall,
• A fuze, to adjust the triggering altitude of the explosive charge, and being adjustable to settings of 1,000 m (3,300 ft) or 1,500 m (4,900 ft),
• 6 rocket engines and their fuel (3.4 kg (7.5 lb)), for propulsion, providing a maximal range of 4,750 m (15,580 ft).
  • The engines were arranged to provide rotational motion, stabilizing the rocket in flight.

These rockets were deployed on a 28 tubes capacity rocket launcher, each rack having a length of 1 m (3.3 ft), and linked to the ship's anti-aircraft fire control system. The rockets were fired in pairs, with the ability to fire all 14 salvos in just 10 s, the rockets reaching a speed of 200 m/s (450 mph). The rockets had a maximum range of 4.8 km (16,000 ft), with a maximum altitude of 2.6 km (8,500 ft).

See also

• San Shiki (anti-aircraft shell), using a similar technology.

External links

• 12 cm (4.7") AA Rocket
• US Naval Technical Mission to Japan (No. O-19)
• US Naval Technical Mission to Japan (No. O-50(N))