Patent GB-378087-A (GB)
Title: Fuse for rotating projectiles
IPC: F42C1/02
Filed: 1931-05-08
Abstract: 378,087. Projectile fuzes. BRANDT, E. W., 101, Boulevard Murat, Paris. May 8, 1931, No. 13626. Convention date, June 4, 1930. [Class 9 (i).] Relates to percussion fuzes of the kind in which a centrifugal device arms the fuze after discharge from a gun but disarms it again if the rotational velocity of the projectile falls below a predetermined value before impact. According to the invention, a spring or springs opposing the centrifugal force on the aforesaid device serves also to hold the firing-pin and the primer apart from each other. As shown in the Figure, a direct impact striker 1 has an inclined shoulder 13 bearing on balls 8 confined in a conical hollow seat 12 by a sleeve 10 urged downwards by a spring 11, which takes its abutment against a shoulder 1a on the striker 1 and thus serves also to hold the striker forward against an inturned lip 17 of the fuze body 4. The head 14 of the striker may be substantially flat or may be rounded or shaped as shown to complete the profile of the projectile to reduce air resistance. Air from the atmosphere may be admitted behind the striker head to help the spring 11 in holding the striker in the forward position. On discharge, the inertia of the parts holds them in the safety position until acceleration is over. Centrifugal force then gradually takes charge and drives the balls 8 outwards clear of the shoulder 13, leaving the striker free to be driven in on impact. The moment at which the arming is performed depends among other things on the angle of the conical recess 12, which may be flared as shown, and on the coefficient of friction between the moving parts. The friction may be increased by lining the recess 12 with a plastic material. Radial races may also be provided in the recess 12 or in the bottom flange of the sleeve 10 to guide the balls 8. If the centrifugal force drops below a predetermined value before impact occurs, the spring 11 forces the balls 8 back under the shoulder 13, thus again disarming the fuze. The striker may be weakened above the shoulder 13 by perforations or by reducing its section to the form of a cross, so than an impact when it is locked by the balls 8 may cause its collapse without driving it on to the primer 20. The point 19 of the striker and the covering disc 23 of the primer may be made soft and hard respectively as described in Specification 265,955, [Class 9 (i), Ammunition &,c.]. The primer is secured in the fuze body 4 by a screw ring 21 ; and the fuze body 4 is screwed into the container 5 of the detonator 24, which is itself screwed into the projectile body 3. Plastic washers 26, 27 are inserted above the primer and detonator. The lower end of the detonator may be rounded. The detonator may be in one with the primer, being constituted by a single charge of fulminate having its upper part less heavily compressed than its main lower part. The detonator may project into a front chamber of the projectile provided with a shoulder tending to support the charge around the detonator against inertia forces on discharge. The seat 12 of the balls 8 may be flat and a cone recess formed instead in the rear end of the sleeve 10. The spring 11 may be replaced by a resilient cork or like washer around a short striker. The Specification as open to inspection under Sect. 91 (3) (a) describes also (1) modifications in which centrifugal balls or segments move in radial or oblique guideways under control of springs independent of the spring 11, or the centrifugal device takes the form of spring arms ; and (2) modifications in which the centrifugal balls cause the striker to project forward, and in which the striker is made to collapse or shear a wire on impact. This subject-matter does not appear in the Specification as accepted.