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"Japanese Air Bombs (Army and Navy)" from Tactical and Technical Trends

A report on WWII Japanese bombs, from Tactical and Technical Trends, No. 37, November 4, 1943.

[DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


There is no separate Japanese air force such as the RAF and Luftwaffe and aerial operations are carried on by special departments of the Army and Navy. There is, therefore, a very distinct difference between the aircraft, bombs, fuzes, etc., produced by these two departments, both of which seem to have developed quite independently. Army aircraft are land-based entirely, whereas Navy aircraft are both carrier-based and land-based. Bomb racks, release mechanisms and fuze arming devices are quite different.

Listed below are the main general distinctions between army and navy types of bombs and fuzes. It is fully realized that these distinctions do not exist in all cases.

a. Body Construction

Army types have a screw-in nose-piece, and a tail unit welded to the main body. In naval types the tail cone is connected to the body by a separate internal insert; the nose is located by rivets or a weld, while the tail-unit is affixed by set screws; it is thus possible to remove the tail piece easily, by removing the set screws but not the nose piece. Suspension lugs are quite different because of the different types of release mechanisms; the army type is rectangular and hinged, while the navy type is a fixed U-bolt.

b. HE Fillings and Exploders

The general HE filling in army bombs is picric acid, contained in waxed cardboard containers and comprising three portions - nose, body, tail. Each portion is a loose fit inside the bomb and is retained by wax. The usual HE filling in navy bombs is hexanite and anisol mixture, or trinitroanisol, poured into the casing; the tail cone filling - if present - is separate and divided from the main portion by a cardboard washer. There are small standard army type boosters which initiate the main fillings, by means of an auxiliary picric acid booster. No navy standard type auxiliary boosters exist, the main fillings being initiated direct by a large standard booster screwed directly into the fuze base.

c. Markings

Markings on bombs give an indication of the arsenals in which manufactured. Some arsenals, such as at Tokyo, Osaka, Nagoya, Sakai are military; others (e.g. at Kure) are naval. Each arsenal has its characteristic Japanese inscription. It is thus easily possible to find the type (i.e. service) of bomb by noting the arsenal of manufacture. Naval munitions are usually marked with an anchor.

d. Bomb Classification The following is a list of Japanese army and navy aircraft bombs taken from a British official source. It may be noted that bombs dropped on one area are normally of the same service. In the Ceylon raids (carrier-based aircraft) naval types were dropped.

e. Army Type Bombs

0.73 lb HE hollow charge
2.2 lb antipersonnel, incendiary
26.4 lb thermite incendiary (alleged)
33.1 lb HE antipersonnel
66.1 lb HE general purpose
110.2 lb HE general purpose
110.2 lb HE general purpose (modified)
110.2 lb phosphorus incendiary, Type 97
110.2/132.2 lb HE, incendiary, phosphorus
220.2 lb HE general purpose
550.8 lb HE general purpose (alleged)
Leaflet bomb

f. Navy Type Bombs

110.2/132.2 lb thermite incendiary
132.2 lb wax incendiary
132.2 lb HE general purpose Type 97
132.2 lb HE general purpose
132.2 lb HE general purpose Type 98
132.2 lb HE general purpose Type 99
550.8 lb HE general purpose Type I
550.8 lb HE general purpose Type II
550.8 lb HE semi armor-piercing (alleged)
550.8 lb HE incendiary
1,102.0 lb HE semi armor-piercing (alleged)
1,652.4 lb HE AP

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