Patent GB-1283914-A (GB)
Title: Improvements in or relating to arming devices
Inventor: SHARPE ARCHIBALD WALTER
IPC: F42C15/30
Filed: 1968-08-16
Abstract: 1283914 Projectile fuze SPERRY RAND Ltd 13 Nov 1969 [16 Aug 1968] 39426/68 Heading F3A [Also in Division G1] A fuze for guided missiles comprises a plurality of misaligned fuze components which are first released by locking means responsive to fluid pressure but are prevented from moving to an aligned, armed condition by further locking means which are only released by a doubleintegrating accelerometer when the missile has travelled through a predetermined distance as measured by the accelerometer. The accelerometer (Fig. 8, not shown) comprises a member (14) movable by inertial forces and coupled to a flywheel (32) via a gear train (26). A clutch (27) may be included to reset the accelerometer after testing the fuze. The fluid pressure is derived from the motor gases of the missile, the ram air pressure during flight, or the thermal expansion of a fluid heated by the motor gases or kinetic air compression. Electrical means for igniting the explosive fuze train are maintained in open circuit whilst the train components are misaligned. The circuit includes a storage capacitor which is charged immediately prior to launching and allowed to discharge via a pulse transformer only after arming has taken place and a solid state switch has been triggered by a fuze, an impact device, a target proximity device, a command signal from the launching point or due to failure of internal power supplies or discrete guidance functions. In one embodiment, Fig. 2, a portion 42 of the explosive fuze train is carried in a pallet 4 which is rotatable in an anti-clockwise direction about a pivot 42 by a spring 43. The end 61 of a rotatable arm 62 of a stop 6 bears against a surface 47 of the pallet to prevent rotation of the pallet. A plunger 15 forming part of the accelerometer is secured adjacent a latch 69, which is in the plane of the pallet 4, by a portion 50 of the pallet. A head 39 of a timing device (Fig. 10, not shown) comprising a star wheel (35) and a pallet (36) for controlling the movement of a slide (37) under the effect of inertia, bears against a step 49 of the pallet. A follower 56 for a cam surface 46 of the pallet forms part of a switch in the electrical firing circuit. When the missile is launched, the motor gas pressure actuates a piston-rod 64 and causes the rod 62 to release the pallet. The rotation of the pallet permitted thereby is limited by the latch 69 engaging the surface 48 of the pallet, and the head 39 of the timing device entering a detent 44 in the pallet. After the head 39 of the timing device has moved out of the detent 44 after a delay, and after the plunger 15 of the accelerometer, now freed from the pallet portion 50, has displaced the latch 69 out of the plane of the pallet, the pallet rotates to an armed position determined by a stop 76. The follower 56 enters a detent 59 in the pallet to close contacts in the switch and to prevent reverse rotation of the pallet. The housing 8 is filled with inert gas and includes an inspection window (55, Fig. 3, not shown) for observing the pallet 4. In another embodiment, Fig. 14, with the timing device omitted, the end 61 of the arm 62 holds the accelerometer plunger and the latch 69 at safe, whilst an extension 80 engages a recess 81 in the pallet. In a further embodiment, Fig. 15, also with the timing device omitted, an explosive motor or electromagnetic device 83 connected to a fluid pressure switch 85, acts on an extension 82 of the arm 83 to free the pallet 4. A pneumatic actuator 87 is used instead of the explosive motor when testing the fuze. Instead of the accelerometer being arranged to release the latch 69 as described in the previous embodiments, it may be arranged to actuate an electrical switch, whereby power is supplied to an explosive motor for releasing the latch. Also, the movable member of the accelerometer may carry the movable fuze train portion and moves the member into alignment with the rest of the train when the missile has moved through a predetermined distance.