This is a direct action base fuze used in the 15 cm H.E. rocket. It may be identified by the stamping "Bd.Z. DOV" in the base. The overall length of the fuze is 1.4 inches and its maximum diameter, over the threads, is 1.75 inches.

The fuze consists of a steel body, steel needle, five centrifugal segments of light alloy, expanding spring ring, creep spring, steel detonator holder, igniferous detonator and steel screwed plug. All steel components are rustproofed.

The body is screwthreaded externally with a left-band thread for insertion in the base of the rocket, and the forward end is reduced in diameter and screwthreaded for the at-tachment of the detonator holder. It is bored centrally from the front in two diameters to form chambers to house the needle pellet and centrifugal segments.

The needle is integral with the inertia pellet. The pellet is housed in the base of the body, and provided with two shoulders below the needle, which is located centrally in the larger chamber.

The five centrifugal segments are pivoted on pins and are shaped so that one locks the other. In the unarmed position, the segments engage the larger shoulder of the needle pellet and hold the needle off the detonator. They are surrounded and retained in this position by an expanding spring ring.

The spiral creep spring surrounding the needle is held between the smaller shoulder of the needle pellet and a seating in the detonator holder.

The detonator holder is bored centrally to form two chambers, which are connected by a coned boring with a seating for one end of the creep spring. The larger chamber is screwthreaded to receive the forward end of the fuze body. The smaller chamber houses an igniferous detonator and is closed by a perforated screwed plug secured by stabbing.

The needle is held off the detonator by the centrifugal segments which are retained in the closed position by the expanding spring ring.

On deceleration, and when the necessary rotational velocity is reached, the segments, overcoming the spring ring, swing outwards under centrifugal force clear of the needle pellet. Creep action by the needle pellet is prevented by the creep spring.

On impact or graze, the pellet moves forward, compressing the creep spring and the needle on to the detonator.

Fig. 9