Introduction

The contents of this section are divided into two main parts, Japanese Army bombs and Japanese Navy bombs.

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 in 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 con-ducting antisubmarine warfare.

The Japanese designation of bombs are used in this book. A general discussion of the system is presented here. A more detailed explanation is given in the introduction to each section.

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 designa-ted by the year of era. Now, however, the year of the Japanese Empire (Japanese year 2600 corresponds to our 1940) may be used. For item 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 respresented 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 single 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 of a change in explo-sive filling.