Introduction
The Japanese Army and Navy have separate air forces each of which employs its own distinct types of bombs and fuzes. These ordnance items are dissimilar in construction and identification features, and each service utilizes its own system of designation.
For the most part the two types of bombs and fuzes may not be used interchangeably. Special adapters have been developed, however, which allow some flexibility of this rule. This has been particularly demonstrated in the use of Navy bombs by the Army in conducting antisubmarine warfare.
System of designation:
1. Type number - Items of ordnance, as well as most other items of military equipment, are given a type number indicating the year the article was finally adopted for service use. This may occur several years after the ordnance has been in production and actual use.
Until the reign of the present emperor, (Showa era; started in 1926) items were designated by the year of era. Now, however, the year of the Japanese Empire (Japanese year 2600 corresponds to our 1940) may be used. For items introduced up to the year 2600 the last two numbers are used in the designation. Thus type 99 means the item was adopted in 2599 or our 1939.
The year 2600 may be represented as type 100 or type 0, in a designation. The years 2601, 2602, etc., are usually represent by the last digit such as type 1, type 2, etc.
Experimental Ordnance items are assigned experimental type numbers indicating the year of the Showa era during which the experiment was authorized.
Ordnance items standardized in the eras preceding the Showa era; namely, Taisho 1912-1926 and Meiji 1867-1912, will be designated by the era and the year of the era. Type II (Taisho) = 1922, type 41 (Meiji) = 1908.
2. Mark number - Some ordnance such as Navy bombs developed for a special purpose will be designated by a mark number.
3. Description of ordnance - Some items may have a word or two following the type number which gives a brief description of the particular piece of ordnance.
4. Model - This term has several meanings but generally it indicates a change in basic design.
5. Modification - This is used to represent minor changes in design or a change in explosive filling.
Designation
The Japanese Army designates its bombs according to a type number, weight, and sometimes a descriptive title.
a. The type number indicates the year in which the bomb was adopted for service use.
b. The weight is expressed in kilograms and usually is stenciled on the bomb.
c. The descriptive title is not used on the standard high-explosive bombs but is used on others. The descriptive title such as smoke, incendiary, gas, substitute, practice, and antishipping, indicate the purpose of the bomb.
Construction
The standard high explosive bombs are of three piece construction. On older bombs the tail cone, which is filled with explosive, is welded to the cylindrical body, and the nose section is threaded to the body. In later models the nose is welded to the body and the tail cone is threaded on.
Some of the antishipping bombs utilize two piece construction; the nose and body are of one piece, and the tail cone is threaded to the body. The special construction features of the various antishipping bombs are described under the individual bombs.
Suspension
All the Army bombs except those carried in containers are suspended by a single hinged rectangular lug located at the center of gravity.
Filling
High explosive bombs are usually filled with precast, paper-wrapped blocks of explosive surrounded by paraffin, or in the latest type by cast TNT. When fillings other than picric acid are used, the nature of the filling may be stenciled on the bomb. Bombs filled with an explosive other than the standard filling for that bomb are marked with the Jap character for "special".
Color and markings
High explosive bombs are painted black overall. A red band around the tip of the nose indicates that the explosive is loaded in the bomb case. A white band forward of the suspension lug indicates that the bomb case is made of high-grade steel. A yellow band forward of the white band denotes a high-explosive filling. Recently this system has been modified to the extent that the white band has been omitted. Forward of the yellow band is stenciled the type number, weight, filling, and additional description. Aft of the suspension lug is stenciled the place and the date of manufacture and a "+" or "-" indicating a minor weight discrepancy.
Incendiary bombs with a solid filling are painted black overall with a white band forward of the suspension lug.
A symbol for incendiary bombs is stenciled on the bomb.
All liquid filled bombs are painted grey overall. A red nose tip indicates that the high explosive burster tube is loaded and a blue band aft of the nose tip indicates that the liquid filling is present.
Liquid filled incendiary bombs are marked by a single white band just forward of the suspension lug and by the symbol.
Liquid-filled smoke bombs are grey overall, have a red nose band and no body band. They are marked by the symbol for smoke.
Gas bombs are painted grey overall and have a red nose band. It is supposed that color bands around the body indicate the type of gas filling. This system is utilized in marking Army gas projectiles.
Red band - Vomit gas.
Blue band - Lung irritant.
Green band - Tear gas.
Yellow band - Vesicant.
Brown band - Blood and nerve poison.
Sizes
Although documents refer to 1,000 kg bombs, none larger than 500 kg has been recovered.
Fuzing
All Army bombs of 30 kg. and above may be fuzed in both the nose and tail. Bombs of 250 and 500 kg generally use larger weight.
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