Patent GB-827120-A (GB)
Title: Improvements in and relating to a percussion fuze
IPC: F42C9/16
Filed: 1958-02-24
Abstract: 827,120. Ammunition fuzes. HOTCHKISSBRANDT. Feb. 24, 1958 [Feb. 26, 1957], No. 5868/58. Class 9(1) A direct action fuze provided with selfdestruction means and intended for use in rockets and like self-prepelled missiles has a body 1 screwed to a nose-cap 4 having a stepped axial bore housing the percussion elements and separated by a partition 10 from a transverse cylindrical bore housing a detonator and communicating with an aperture 12 containing a relay charge D to ignite a booster charge E used to fire the main explosive charge. A cylindrical guide tube 14 bearing against a shoulder 6 divides the axial bore in the fuze into an inner chamber containing firing means A and a peripheral chamber housing a safety device B which holds the means A inoperative before launching. The firing unit A comprises a primer carrier 15 and a striker mechanism movable relatively to one another but held apart by locking balls 27, 57. The carrier 15 has a stepped outer surface with a shoulder 19 corresponding to a shoulder 22 within the guide tube 14. Leading from the primer 23 in the carrier 15 is a flash tube 24 which extends into a recess in the detonator slide 59 to hold the detonater at safe. The device B comprises a spring-pressed sleeve 30 holding the balls 27 in position and a tube 32 having a zig-zag groove 34 engaged by a stud 33. The striker mechanism consists of a forward part P 1  and a rearward part P 2 , the part P 1  comprising a cylinder 38 to the forward end of which a shear plate 40 is riveted, the plate 40 being secured in the nose of the fuze by a flange 41. A liquid 45, such as a silicone, filling the cylinder 38 is retained therein by a spring-stressed piston 42 having a flatted surface 44 past which the liquid can escape when the piston moves forwards. A washer 47, e.g. of rubber, provides a fluid seal between the piston and the rear end 48 of the cylinder. Part P 2  consists of a striker pin 49 extending through a ring 52 pressed against the balls 57 by a spring 55 and secured to the pin 49 by a shear pin 53. A bolt 65 projecting into a groove 66 prevents rotation of the detonator slide 59. On discharge of the projectile the tube 32 sets back due to inertia, its rearward motionbraked by the stud 33, and forces the sleeve 30 rearwardly to free the balls 27. When the tube 32 reaches its rearmost position, resilient tabs 36 on a sleeve 35 spring into a recess 37 to prevent a return movement of the tube 32. Upon escape of the balls 27, the primer carrier 15 is thrust forward by its spring together with the part P 2  of the striker mechanism, the forward motion being controlled by the dash-pot 38, 42. On withdrawal of the tube 24, the slide 59 moves until the detonator 62 is aligned with the primer 23 and the relay D. The fuze is thus armed for operation on impact, at which the plate 40 shears and drives the striker rearwardly, the motion being delayed by the dash-pot. At the same time the pin 53 shears so that the pin 49 passes through the ring 52 to hit the primer 23. If impact does not occur before forward movement of the carrier 15 carries the balls 57 past the shoulder 22, the balls move outwards and release the part P 2  which is then driven against the primer 23 by its spring 55 to produce self-destruction of the projectile. In a modification for projectiles fired from guns, the arming delay groove 33 and stud 34 are omitted, Fig. 5. The sleeve 30a moves rearwardly when the projectile is fired and so frees the balls 27 and compresses its support spring 31. Tabs 36 engage a recess 37a to lock the sleeve 30a in the rear position. Spring 26 drives the primer carrier 15a and part P 2  forward as in the first embodiment. The cylinder 38 may be made of an aluminium alloy or brass and the piston of methyl polymethacrylate if the liquid 45 is a silicone of viscosity 1-5 between +60‹C. and -40‹C. Specification 815,268 is referred to.