Japanese Army fuzes utilize a charcateristic type of gaine which differs greatly from that used in Navy fuzes. All Army fuzes use one of the three types of gaine shown below or variations of a slightly different shape but of similar construction. These variations are shown in detail in the particular fuze in which they are used.

Type I and II are used in nose fuzes only, while type III is used only the tail fuzes. Type III is approximately twice as long as type I and II. Type I and III are ignited by the flash from the primer in the fuze. Type II is used in fuzes which have no internal primer and the gaine is pierced directly by the firing pin.

All Army gaines are of brass contruction. They are screwed into the fuze and are staked in position.

Boosters are either contained in a brass cup threaded onto the fuze around the gaine, or in a paper cylinder housed in the main explosive charge of the bomb.

Figure 138 – Army Gaines.

Introduction to Navy Gaines

The Japanese Navy fuzes utilize a characteristic gaine which incorporates within itself the entire explosive train. The gaines are similar in external appearance but vary in size and internal construction. All gaines have two wrench flats just below the threads but they are generally screwed (right hand threads) into the fuze only hand tight.

Japanese Navy gaines are generally made of brass, cadmium plated and lacquered. More recently, specimens made of steel have been recovered. The component internal parts of the gaines are: (1) Primer plugs, screwed in and staked, (2) Delay plugs, slip fits, (3) De-tonator plugs, screwed in or slip fits, and (4) Booster, precast, slip fit.

The delay incorporated within the gaine is indicated by a colored tip. No standard set of figures has been arrived at regarding the times or delay. The information taken from Ja-pa nese documents does not agree with the results of laboratory tests. The figures listed on the following pages are taken from Japanese documents.

Figure 139 – Introduction of Navy Gaines.