Italian bomb fuzes are all mechanically operated, except for the time fuzes for the 500-kg time bomb; and most of the Italians bomb fuzes function upon impact. The principle of arming and functioning is the same for most tail and nose fuze. Arming takes place during the fall of the bomb and depends upon the rotation of the arming vanes. The primary safety device is always the safety pin, which is withdraw before the bomb is dropped. The fuze can be handled with relatively little danger when the safety pin is present. Nor-mally, the fuzes are made of brass, steel, or aluminum and are coated with shellac or varnish to resist corrosion.

Tail fuzes are screwed into the base of the bomb and contain a cylindrical steel tube which extends the whole length of the tail. The end of the bomb tail is shaped to accom-modate the arming vanes. In most cases the striker is immobilized in the unarmed condi-tions by steel balls resting against either a groove or a sleeve in the fuze body. The balls either are prevented from moving inwards by an arming spindle, attached directly to va-nes which unscrew and rise above the collar into which the spindle screws, or are threaded to a rod or tube attached directly to the vanes. In the latter case, there is no external evidence of arming, since the arming spindle screws either into or onto the tube or rod attached to the arming vanes, and the vanes do not rise as in the case where the arming spindle is attached directly to the vanes.

The striker for many tail fuzes has more than one iring pin in order to insure detonation of the bomb. Where two or more firing pins are used, the striker always has a guide to keep the firing pin and detonator caps in line. In most cases, the striker is held in the armed condition by a creep spring, and the detonator is stationary. These fuze are operated by the arming spindle, which rises, thus freeing the steel balls, which move inward to free the striker. On impact, the striker overcomes the creep spring and hits the detonator.

Nose fuzes allow a considerably wider variation in operation than do the tail fuzes. Most of the nose fuzes may be divided into two general types: those which are armed by ro-tation and the subsequently firing away of a vane cap; and those which are armed by the simple roatation of the vanes. In the former case, the absence of the cap indicates arming of the fuze; but in the latter case, it is more difficult to decide the question or arming.

Most nose fuzes have steel balls which lock either the striker or the sleeve holding the detonator. The functioning in all cases depends on either the cap or the arming spindle, which rises to free the steel balls. These then move either out-wards or inward to free the detonator sleeve or unlock the striker. In the case where the detonator is movable, a creep spring is incorporated in the design; but, when the striker is movable, a shear washer or a pin is used.

Italian time fuzes are of two types: one for aerial burst, which depends on the certain number of rotations of the vanes for funtioning; and the other, a long-delay, which de-pends on a clockwork for delay, but which arms the same as most other Italians fuzes.

The bases of most Italian fuzes are threaded internally to receive a booster. The normal boosters used were of two types, the long type, 7.5 in long, and 1.3 in. external diame-ter; and the short type, 4.8 in. long and 1.3 in diameter. The long booster is screw-threaded at the open end to take an adapter and, below the adapter, contains two com-pressed blocks of TNT; the upper block is recessed to take a booster. The short booster is similar but contains less charge. Different types of adapters are fitted to the booster to give delay action or different length projections of the auxiliary booster which fits into the booster proper. The auxiliary booster is the same for both types and is in an alumi-num tube, the top of which is threaded to a steel plug which fits into the adapter. Above the auxil-iary booster, the booster lead-in pellet is located and, in some cases, it has a realy or delay powder pellet below it.

Figure 38
Bomb Adapters and Boosters