The fuze is used in Q.F. 102 mm 35 calibre anti-aircraft gun ammunition and is a tensio-ned fuze of the combustion type. The screw-threaded portion of the body, for insertion in the shell, is longer than that of the smaller fuze graduated to 13.2. The setting gra-duations extends from zero to 160. A fuze set to 160 gave a time of burning of 35.9 secs. at rest. The design includes a delay arrangement between the lower time ring and the magazine, which ensures a minimum time of burning of 0.6 sec. as in the smaller fuze. The body is screw-threaded to a 1.766 inch diameter, with a pitch of approximately 3 mm.

With the exception of the graduated brass platform, the exposed part of the fuze when fitted in the shell is of aluminium. The nose plug has a flat head, and is shaped to corres-pond with the tapering contour of the tension nut and upper ring. The lower time ring is cylindrical and is milled. The platform is tapered. A brass cover with slight fluting near the nose is attached by a soldered tear-off strip to the lower edge of the platform.

The brass body has a magazine, containing 51 grains of gunpowder, formed in its under-side. The magazine is closed by a screwed brass plug which protrudes from the base of the fuze. The plug has a central flash channel closed by a thin brass disc. Six equispaced recesses, surrounding the flash channel, are drilled from the base of the plug. The plug is secured by means of a set screw. A central channel is formed leading from the magazine to the top of the body. The flash channel between the magazine and the platform is for-med by a radial channel, closed at its outer end by a brass plug, and a vertical channel connecting the radial channel to the surface of the platform. The radial channel contains a solid pellet of powder, which causes a delay of 0.3 sec., and the vertical channel con-tains a brass ring with a hole tapering towards the head, which is filled with pressed powder and also provides a delay of 0.3 sec. The central channel and the radial channel are closed in the magazine by discs of tinfoil. The numbered setting graduations on the flange of the platform extend from zero to 160 and are subdivided in tenths from 0.8 on-wards. The 0.5 setting is also graduated. A radial locking pin of brass is fitted in the body to engage a recess in the fixed upper time ring. The body is screw-threaded near the forward end to receive the tensioning nut, and is reduced in diameter at the head to form a spigot which is threaded to receive the cover plate and two locking nuts. The step formed by the reduction in diameter at the head has formed in it a part-circular groove, the ends of which are connected by inclined grooves with vertical grooves in the recess containing the detonator assembly. This recess is displaced from the centre of the body, and has a steel needle fitted in its base. Two inclined flats are formed at the front end of the recess, on which the arms of the stirrup spring are supported, and a flash channel for the ignition of the upper time ring is formed in the wall of the recess.

The detonator assembly consists of an igniferous detonator carried in a cylindrical brass pellet, which is held away from the needle by a brass stirrup spring.

The lower time ring is the setting ring, and has a powder groove in the underside exten-ding through 320 degrees, with three vents. The first vent corresponds with the com-mencement of the groove, the second is at 115 degrees from this pellet, and the third at 225 degrees. An arrow is inscribed on the milled exterior of the ring for setting, and a re-cess is formed for the setting key.

The upper ring is locked by a radial brass pin in the body. The powder groove in its un-derside extends through the same angle as that in the lower ring, and has vents similary placed except that the first vent is in the solid part of the ring and is connected to the groove by a short channel.

The other details of the rings are the same as those given in the description of the smal-ler fuze.

The brass cover plate consists of a disc with a screw-threaded hole in the centre, and is screwed on the spigot projection on the body to cover the detonator recess and the curved groove in the body.

The cover plat is held by a brass locking nur screwed to the spigot above it.

The tensioning nut is formed with a diaphragm perforated to fit over the spigot on the body, and is screwed over the body to bear on the time rings to produce the required resistance to the turning of the lower ring. After adjustment the tensioning nut is secu-red by a brass locking nut, which is screwed to the spigot and bears on the diaphragm, and by a fixing screw. The nut has an internal screw-thread and a fixing screw for the attachment of the nose plug.

The aluminium nose plug is tapered with a flat top and is screwed into the tensioning nut, with a lead washer sealing the joint.

9.2 per cent

9.6 per cent

75.0 per cent

75.5 per cent

15.3 per cent

14.5 per cent

0.5 per cent

0.4 per cent

On acceleration the detonator pellet overcomes the support of the stirrup spring and sets back, carrying the detonator on to the needle. The flash produced is transmitted to the filling in the upper time ring, and the subsequent action is similar to that of the smal-ler fuze. The groove in the detonator recess and in the front end of the body appear to be designed for the dispersion of the pressure set up by the action of the detonator, and thus avoids disintegration of the powder.