GB1605228A - Missiles - Google Patents

Description

(54) IMPROVEMENTS RELATING TO MISSILES (71) We, BRITISH AEROSPACE PUBLIC LIMITED COMPANY, a British Company organised under British Aerospace (Nominated Company) Order 1980 and British Aerospace (Appointed Day) Order 1980, of 100 Pall Mall, London SW17 5HR, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a missile of the type which is provided with a radiation detecting device which detects radiation reflected from a target, e.g. the radiation may be laser light directed at a target from an aiming source, and reflected by the target, and which on detection of the target causes the missile to be deflected towards the target.

One of the difficulties with such an arrangement is that light-reflecting media such as smoke, fog, foliage, etc lying between the radiation source and the target may cause some of the radiation to be reflected as back-scatter, and this may be of sufficient intensity as to cause the radiation detecting device to operate the missile control system resulting in the deflection of the missile towards the light-reflecting media and not the target.

According to the present invention, a missile of the type described includes a control system, a primary radiation detecting device and a secondary radiation detecting device, the secondary radiation detecting device being provided with a field of view immediately in front of the field of view of the primary detecting device, and an electrical circuit for receiving electrical output signals from the secondary and primary detecting devices and preventing signals from reaching the missile control system when an output signal is produced by the secondary detecting device.

In a preferred form of the invention, each radiation detecting device includes a photoelectric cell mounted in the focal plane of a lens, and the electrical circuit includes a gate which is closed by an output from the secondary detecting device and which is opened when the output from the secondary detecting device ceases; signals from the primary detecting device being fed via the gate to the missile control system.

One embodiment of the invention will now be described by way of example and with reference to the accompanying drawing which shows diagrammatically a missile flying towards an illuminated target.

The missile 1, which is of a kind having an ejectable slug or mass in its body portion in the vicinity of the centre of gravity of the missile, spins about its longitudinal axis as it flies along a path 2. In the nose of the missile is a primary radiation detecting device 3 and a secondary radiation detecting device 4. The devices 3 and 4 each include a photoelectric cell, 7, 8 respectively; lens 5 focusing light on to the two photoelectric cells 7 and 8. The outputs from the devices 3 and 4 are fed to amplifiers 9 and 10. The outputs from both amplifiers are fed to a gating circuit 11 the output from which controls the firing of a mass 12 from the side of the missile, the ejection of the mass modifying almost instantaneously the trajectory of the missile so as to deflect the missile towards the target.

The devices 3 and 4 are arranged to observe fields of view 13 and 14 respectively through slits in the nose portion of the missile, the field of view 14 being in advance of the field of view 13. It will be understood that as the missile spins during its flight the fields of view 13 and 14 will be continuously swept around the missile flight path so that for part of the time during one revolution of the missile the devices 3 and 4 will be observing sky whilst during the remainder of the time during that revolution they will be observing ground. In effect, the devices 3 and 4 will each be looking along a corkscrew path with the field of view of device 4 always in advance of that of device 3.

Each device 3 and 4 is able to produce an electrical output when a light spot of sufficient intensity appears in its field of view. Thus, a laser beam 15 aimed from a source, not shown, and reflected by a target 16 will cause the devices 3 and 4 to produce electrical outputs when the reflected light is received by them.

These outputs are supplied through amplifiers 9 and 10 to the gating circuit 11. Provided that an electrical output is being produced by device 4 the output from amplifier 10 will inhibit the gating circuit 11 which thus does not have an output. However, the provision of an output from amplifier 9 following the inhibition of gating circuit 11 will cause an output from the gating circuit to initiate the firing of the mass 12 from the side of the missile.

It can be seen that if the laser beam 15 is aimed at the target 16 in clear air conditions, the target only will reflect the beam and a proportion of this reflected light will be observed firstly by the device 4 and then by the device 3. The output from device 4 merely inhibits the gating circuit 11 but the output from detector 3 causes the gating circuit 11 to supply an electrical output which initiates the firing of the mass 12 from the side of the missile thereby deflecting the missile towards the target. In this condition, where the air is clear and there is nothing in between the source of the beam and the target to cause reflection of the laser beam the detector 4 may well be dispensed with.However, if there happens to be a patch of light reflecting medium 17 such as fog, smoke, leaves, etc in the path of the laser beam, some of the beam will be reflected by that medium and, if the missile were provided with device 3 only, the electrical output from that device due to the receipt of light reflected by the patch of light reflecting medium would initiate the firing of the mass 12 from the side of the missile and the flight of the missile would then be directed towards the patch instead of the target.

In operation, a missile 1 is fired towards a target 16 and, as the missile approaches the target, a source of laser light, not shown, is switched on and a beam of light 14 is directed at the target. The secondary detecting device 4 in the missile detects any reflected light such as may occur from the patch of light reflecting medium 17 and from the target. The resultant electrical signal from device 4 inhibits the gating circuit 11. Regardless of how large is the patch 17, the gating circuit remains inhibited provided that there is an output from the device 4 even though there is also an output from the device 3.As the laser beam 15 is intercepted by the target, there is no laser light reflected from any point beyond the target and so the output from device 4 ceases when the light reflected from the target is no longer seen in its field of view i.e. when the field of view of device 4 passes beyond the target. The output from device 3 remains on however since it still retains light reflected from the target in its field of view and, as gating circuit 11 is no longer inhibited, the output from device 3 causes the initiation of the firing of the mass 12 thereby directing the missile on to the target.

In the plane perpendicular to that illustrated in the accompanying drawing, both fields of view may be narrow. It will then be possible for time differences to occur between the time of generation of the outputs from the two radiation detecting devices. For different trajectories, the signal from either device may be received first. To compensate for this, the signal from device 3 may be delayed for the expected time difference and the inhibition of gating circuit 11 maintained for twice that time.

The invention has been described as applied to a missile in which the deflection of the missile is caused by means of the ejection of a mass from the body of the missile. The deflection of the missile may, however, be achieved by other known means, such as the movement of a control surface or the extension of a plate from the body of the missile.

WHAT WE CLAIM IS: 1. A missile of the type described including a control system, a primary radiation detecting device and a secondary radiation detecting device, the secondary detecting device being provided with a field of view immediately in front of the field of view of the primary detecting device, and an electrical circuit for receiving electrical signals from the secondary and primary detecting devices and preventing signals from reaching the missile control system when an output is produced by the secondary detecting device.

2. A missile as claimed in Claim 1 including a lens, and each radiation detecting device including a photoelectric cell mounted in the focal plane of the lens so that light may be focused on to each cell.

3. A missile as claimed in Claims 1 or 2 wherein the electrical circuit includes a gate which is closed by the output from the secondary detecting device and which is opened when the output from the secondary detecting device ceases, the gate being connected between the primary detecting device and the missile control system.

4. A missile substantially as described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. gating circuit 11 which thus does not have an output. However, the provision of an output from amplifier 9 following the inhibition of gating circuit 11 will cause an output from the gating circuit to initiate the firing of the mass 12 from the side of the missile. It can be seen that if the laser beam 15 is aimed at the target 16 in clear air conditions, the target only will reflect the beam and a proportion of this reflected light will be observed firstly by the device 4 and then by the device 3. The output from device 4 merely inhibits the gating circuit 11 but the output from detector 3 causes the gating circuit 11 to supply an electrical output which initiates the firing of the mass 12 from the side of the missile thereby deflecting the missile towards the target. In this condition, where the air is clear and there is nothing in between the source of the beam and the target to cause reflection of the laser beam the detector 4 may well be dispensed with.However, if there happens to be a patch of light reflecting medium 17 such as fog, smoke, leaves, etc in the path of the laser beam, some of the beam will be reflected by that medium and, if the missile were provided with device 3 only, the electrical output from that device due to the receipt of light reflected by the patch of light reflecting medium would initiate the firing of the mass 12 from the side of the missile and the flight of the missile would then be directed towards the patch instead of the target. In operation, a missile 1 is fired towards a target 16 and, as the missile approaches the target, a source of laser light, not shown, is switched on and a beam of light 14 is directed at the target. The secondary detecting device 4 in the missile detects any reflected light such as may occur from the patch of light reflecting medium 17 and from the target. The resultant electrical signal from device 4 inhibits the gating circuit 11. Regardless of how large is the patch 17, the gating circuit remains inhibited provided that there is an output from the device 4 even though there is also an output from the device 3.As the laser beam 15 is intercepted by the target, there is no laser light reflected from any point beyond the target and so the output from device 4 ceases when the light reflected from the target is no longer seen in its field of view i.e. when the field of view of device 4 passes beyond the target. The output from device 3 remains on however since it still retains light reflected from the target in its field of view and, as gating circuit 11 is no longer inhibited, the output from device 3 causes the initiation of the firing of the mass 12 thereby directing the missile on to the target. In the plane perpendicular to that illustrated in the accompanying drawing, both fields of view may be narrow. It will then be possible for time differences to occur between the time of generation of the outputs from the two radiation detecting devices. For different trajectories, the signal from either device may be received first. To compensate for this, the signal from device 3 may be delayed for the expected time difference and the inhibition of gating circuit 11 maintained for twice that time. The invention has been described as applied to a missile in which the deflection of the missile is caused by means of the ejection of a mass from the body of the missile. The deflection of the missile may, however, be achieved by other known means, such as the movement of a control surface or the extension of a plate from the body of the missile. WHAT WE CLAIM IS:

1. A missile of the type described including a control system, a primary radiation detecting device and a secondary radiation detecting device, the secondary detecting device being provided with a field of view immediately in front of the field of view of the primary detecting device, and an electrical circuit for receiving electrical signals from the secondary and primary detecting devices and preventing signals from reaching the missile control system when an output is produced by the secondary detecting device.

2. A missile as claimed in Claim 1 including a lens, and each radiation detecting device including a photoelectric cell mounted in the focal plane of the lens so that light may be focused on to each cell.

3. A missile as claimed in Claims 1 or 2 wherein the electrical circuit includes a gate which is closed by the output from the secondary detecting device and which is opened when the output from the secondary detecting device ceases, the gate being connected between the primary detecting device and the missile control system.

4. A missile substantially as described with reference to the accompanying drawing.