GB677901A - - Google Patents

Abstract

677,901. Projectile fuzes. ROSSELET, J. May 23, 1949. [May 28, 1948] No. 13740/49. Class 9 (i). Setting mechanism of a fuze adapted to be mounted in the nose of a projectile comprises a body 1 containing an inertia member 2/4 of generally cylindrical form, the rear part 4 having two diametral slots 6 in which are four setting elements 7. The elements 7 are in the form of discs rolling upon their edges along ramps 9, 10 formed by frusto-conical surfaces in the body 1. The member 2/4 is held against forward movement by a split ring 8, a spring 15 (not shown) forcing the member rearwardly. The ring 8 opens out under centrifugal force. At discharge of the projectile the elements 7 rest on the base of the body 1 and are urged outwardly against the ramp 9 by centrifugal force. After the projectile leaves the muzzle, due to the retarding forces acting on the projectile the elements 7 travel along the ramps 9, 10 and come to bear against the upper part 2 of the member 2/4 and occupy the positions 14. The elements 7 force the member 2/4 forwardly against the action of the spring 15 and move into the positions 16. This movement may be used to set the fuze directly or indirectly. The movement of the elements 7 is governed by the centrifugal acceleration 12, the forward acceleration 13, the coefficient of rolling friction, the diameter of the elements and the inclination 18 of the ramp to the longitudinal axis of the fuze (Fig. 3). The angle 18 is less than 5 degrees and may be less than 3 degrees. The member 2/4 may be in two parts, the part 4 being fixed. The setting elements may be in the form of balls and the lower part 4 may be omitted. The slope of the ramp 9 may diminish to zero or less as it approaches the second ramp and the transition to the second ramp may be rounded. The slope of the second ramp exceeds 12 degrees. Fig. 5 shows the setting mechanism. mounted in a percussion fuze comprising a body 31 closed by a plug 32. The plug 32 has a cuplike recess containing balls 34 holding back a striker 35. On the striker rests a 36/37 accommodating setting element 40 and surrounded by a ring 41 with guide surfaces or ramps 42, 43. After discharge of the projectile the elements 40 move along the ramps and force the member 36/37 forwards against the action of a spring 48 surrounding a plunger 46. The balls 34 escape into recesses 44 in the ring 41 thus freeing the striker 35 so that the fuze is set. On impact a sealing disc 50 is broken and a push-piece 47 is forced rearwardly, thus driving the plunger on to the striker to initiate a primer (not shown). The fuze is arranged to be self-destroying. As the velocity of the projectile decreases, the centrifugal force on the elements 40 also decreases and when its axial componenet is less than the force due to the spring 48, the member 36/37 moves rearwardly to initiate the percussion elements. The preferred setting elements are discs with a radius of curvature equal to the minimum radius of curvature of the first ramp. The discs may be of non-ferrous metal such as brass. Specification 665,494 is referred to.