GB1511478A - Apparatus for recording the passage of a missile past a target - Google Patents

Abstract

1511478 Photographing moving objects DE HAVILLAND AIRCRAFT CO Ltd 8 Sept 1961 [30 Sept 1960] 33610/60 Heading G2A Apparatus for recording the passage of a missile past a target comprises an array of photo-sensitive detectors on the target centred on an axis parallel or nearly so to the intended relative path of the missile part of the target, the response from the array being used to operate at least one pair of wide angle single shot cameras disposed on an axis normal to the array axis. In Fig. 1 the target aircraft 10 is provided with six sets 20 each of two similar wide angle single shot cameras, one pair of sets being on the top and bottom of each engine and one pair in the nose of the aircraft. The sets of cameras of each pair are disposed in opposite directions on axes normal to the longitudinal axis of the aircraft and each camera has a hemispherical field of view. Also mounted on the nose of the aircraft is an array of photo-sensitive detectors 28 centred on the axis of the aircraft and including two optical systems by each of which radiations in a field of view 30 of defined angular width are admitted. The optical systems are disposed on opposite sides of the nose and face in opposite directions, each field of view having an extent slightly greater than 180 degrees in a plane normal to the axis of the aircraft. In operation a missile 18 provided with a heat source, e.g. a jet pipe or observation flare, is discharged towards the target aircraft and causes a pulse in the photo-sensitive cells as it enters and as it leaves the field of view 30. The first pulse opens a gate, Fig. 3 (not shown), and the second pulse passes through the gate to operate the first camera of each set. The cameras being triangulated, the resultant photographs disclose the exact track of the missile. A further missile can be launched against the target and photographs taken by the second cameras. If the target is turning at or less than its maximum rate of turn, pulses produced by the sun or a false source of radiant energy follow each other with too long an interval, and the circuit prevents the cameras being operated. Difficulties in discrimination against the sun or other false sources may arise with the use of a single beam array, and in a second embodiment, Fig. 2 (not shown), the optical system provides two fields of view centred in conical surfaces lying at 80 degrees and 100 degrees to the axis of the aircraft. A missile on a course nearly parallel to the target will then produce two pulses sufficiently closely spaced to operate the cameras, but if the missile is travelling at right angles to the target the pulses will be too widely spaced and the cameras will not be operated. To obviate this difficulty a further detector array may be provided mounted on an axis normal to the aircraft axis, Fig. 4 (not shown). In a modification of this arrangement, Fig. 5 (not shown), the fields of view of the arrays are centred on axes at 45 degrees to the vertical and horizontal.