GB2166525A

GB2166525A - Impact detector

Info

Publication number: GB2166525A
Application number: GB08526370A
Authority: GB
Inventors: Paul Carre
Original assignee: SERAT
Current assignee: SERAT
Priority date: 1984-10-30
Filing date: 1985-10-25
Publication date: 1986-05-08
Also published as: DE3538093C2; GB8526370D0; FR2572514B1; FR2572514A1; GB2166525B; DE3538093A1

Abstract

In an impact detector for missiles and rockets, an opto-electronic device (7) emits a luminous signal through an optical fibre system comprising outward and return fibres connected by a reflecting surface, displacement of which upon impact varies the luminous flux to cause device (7) to generate a firing signal. The reflecting surface may be the edge (5) of a window in a homing device or a ring 15 carried by an extendable antenna 14. Upon extension the antenna is locked in a position which arms the system by aligning the ring 15 and optical fibres 20 and allows subsequent disalignment upon impact. The antenna may be destructible upon impact by winding therearound a detonation fuse (23), a pyrotechnic chain to the fuse being completed upon extension. <IMAGE>

Description

SPECIFICATION Opto-electronic impact detector for missiles, rockets and the like The present invention relates to an impact detector for missiles and similar devices.

It is known that most missiles, rockets and other devices use electric firing to initiate their explosive charge. These firing systems are triggered by impact detectors of diverse types: circuit-making or -breaking contact warheads, inertia contacts, piezo-electric sensors, or any other electric device.

All these known systems present one major disadvantage: they are sensitive to electromagnetic attack. Furthermore, they are often complex, costly, bulky or of poor performance.

The impact detector which is the subject of the present invention aims at avoiding these disadvantages.

To this end, the invention relates to an opto-electronic impact detector which enables detection of the impact of a bomb, missile, rocket or other projectile against a target, and the transmission of the impact signal by optical means.

In an embodiment of the invention the fibre optics system consists of a network of optical fibres forming a set of several branches terminating in a light transmission/reception device, the said branches having a break in continuity constituted by a reflecting surface, in such a way that the latter ensures, according to its position in relation to the optical fibres, either the continuity or the interruption of the luminous flux emitted.

In another embodiment of the invention the link between the network of optical fibres and the firing circuit is achieved by an opto-electronic system, ensuring both the transmission and reception of the luminous signal by the device's electrical supply; the variation in the luminous flux is converted into an electric signal by this device according to the invention.

In order that the invention may be better understood several embodiments thereof will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a perspective view of an optoelectronic impact detector according to the invention, for projectiles, missiles or rockets with heads comprising a self-director; Figure 2 is a longitudinal sectional view of an extendable antenna for the warhead of a projectile, missile or bomb, which antenna is the subject of the applicant's French Patent No. 79 09 696, filed on 18th April 1979, the said warhead unit being equipped, according to the invention, with an opto-electronic impact detector. The upper half of the drawing shows the antenna in its extended position.

The lower half of the drawing shows the antenna in its storage position; and Figure 3 is a longitudinal sectional view of an antenna, extendable by means of gas, for a projectile warhead equipped according to the invention with an opto-electronic impact detector. The upper half of the drawing shows the antenna in its extended position. The lower half of the drawing shows the antenna in the storage position.

Referring to Fig. 1, a missile is fitted with a warhead 2 having a housing device or selfdirector 3 comprising a window 4. The edge of the window is fitted with a reflecting surface 5.

Along the sides of the warhead 2 and at its base, there is arranged a system of optical fibres 6, which system is linked to a transmission/reception box 7, linked electrically to the missile firing circuits 8.

In this embodiment the system of fibres 6 is presented in the form of a network of six pairs of optical fibres as at 9, which lead to the reflecting surface 5 of the window 4, through the intermediary of an optical device 10. Each pair of optical fibres comprises one "outward" fibre as at 9' and one "return" fibre as at 9".

The method of operation is as follows: The opto-electronic device 7 emits a luminous signal as shown as it is put under pressure by the weapon case. The luminous flux passes through the optical fibres 6.

If we consider a pair of optical fibres 9, the luminous flux emitted by the device 7 travels along the "outward" fibre 9' and reaches the reflecting surface 5 through the intermediary of the optical device 10. It is reflected by this surface 5 and returns, via the "return" fibre 9" to the transmission/reception device 7 which converts it into a current.

On impact the reflecting surface 5 is displaced in relation to the device 10. This produces a variation in the luminous flux, which is converted into a current variation by the transmission/reception box 7. The signal thus emitted is sent to the firing circuit 8 of the missile's explosive charge.

Another embodiment of the invention is shown in Fig. 2.

This embodiment utilises the principle and method of antenna extension according to the French patent application filed by the applicant on 18th April 1979 under the number 79 09 696.

Referring to Fig. 2, there can be seen the missile 11 fitted with a warhead 12 which has along its axis a channel 13 within which there slides an antenna 14 preferably of composite material. At the rear part of this antenna 14 there is, on the outside, a preferably small reflecting ring 15. The antenna 14 ends in a tip 16 of preferably rigid cellular material. The antenna 14 is held in place by a pin 17. The antenna 14 is slidable within a guide sleeve 18 made preferably of composite material.

This sleeve 18 contains a keeper ring 19.

Along the sides of the warhead 12 there are pairs of optical fibres 20, 20', which lead to the sleeve 18. The antenna 14, when withdrawn, holds a spring 21 under tension.

The method of operation is as follows: At launching the acceleration of the device drives the antenna backwards, shearing off the pin 17. When acceleration ceases the spring 21 relaxes and drives the antenna forwards until the keeper ring 19 slips into a socket 22 provided in the antenna 14. At this position, the reflecting ring 15 faces the pairs of optical fibres 20, 20', thus arming the detection system.

On impact, displacement of the antenna 14 in the guide sleeve 18 (which, due to the shape of the socket 22 may, for example, allow a certain amount of play) causes the reflecting ring 15 and the pairs of optical fibres 20, 20' to move out of alignment and the luminous flux to be interrupted which in turn causes the explosive charge to function.

Another embodiment of an impact detector according to the invention is shown in Fig. 3.

In this variant the missile comprises a warhead 12', fitted with a channel 13' along its axis. A hollow antenna 14', preferably of composite material, slides within this channel.

At the rear part of antenna 14' there is situated, on the outside, a preferably small reflecting ring 15', positioned facing the pairs of optical fibres 20, 20'. On the inner wall of the antenna there is a detonating fuse 23 wound in a spiral and linked at the base of the antenna to a transmission relay 24. The antenna 14' ends in a tip 16' of preferably rigid cellular material. The antenna is pinned in the withdrawn position by a pin 17', as described above. The pairs of optical fibres 20, 20' lead to the antenna sleeve guide 18'.A transmission fuse 25 and associated relay 26 run along the channel 13' The method of operating is as follows: When the missile is launched the antenna 14' is extended out of the warhead 12', for example by a gas-using system using the cruise propeller gases acting, for example, on the bottom 27 of the antenna 14', thus shearing off the retaining pin 17'.

When the antenna 14' is in the extended position the pyrotechnic chain is aligned, which chain consists of the detonating fuse 23 and its relay 24 and the transmission fuse 25 and its relay 26. The reflecting ring 15' is positioned facing the pairs of optical fibres 20, 20', and the detection system is thus armed.

On impact the antenna 14' begins to move back in relation to the warhead 12' of the missile and the optical fibres 20, 20' and the reflecting ring 15' moves out of alignment.

The resultant interruption of the luminous circuit then causes the firing command. Detonation is transmitted to the transmission fuse 25, thence to the missile's explosive charge.

As the relays 26 and 24 are still aligned the detonation spreads into the fuse 23 and brings about the destruction of the antenna, thereby destroying an obstacle which could upset the functioning of the hollow explosive charge, at least in the case of incidental angular impace.

Claims

1. An opto-electronic impact detector for missiles, rockets and similar devices, characterised in that it comprises a system of opti cal fibres coupled to a transmission/reception system operable to transmit a signal for firing the device's explosive charge, and wherein operation is achieved by the detection of a variation in the luminous flux in the said system of fibres.

2. An impact detector according to claim 1, characterised in that the system of optical fibres consists of a network of pairs of optical fibres, each pair forming one of a set of sev eral branches terminating in the luminous flux transmission/reception device, each of said branches having a break in continuity which, depending on its position in relation to the optical fibres, ensures either the continuity or the interruption of the luminous flux.

3. An impact detector according to either one of claims 1 or 2, characterised in that the transmission/reception device converts the variation in the luminous flux into a variation in electrical current, the signal thus emitted being transmitted to the firing circuit of the explosive charge.

4. An impact detector according to any one of the preceding claims, characterised in that each pair of optical fibres comprises an outward fibre and a return fibre, ensuring the transmission and reception of the luminous flux, these outward and return fibres having between them a break in continuity.

5. An impact detector according to any one of the preceding claims, characterised in that the optical fibres are linked together by a reflecting system.

6. An impact detector according to claims 4 and 5, characterised in that the reflecting system consists of the inner face of the warhead of the device, the arrangement being such that its deformation or destruction, on impact, ensures at least partial interruption of the transmission of the luminous flux between the outward fibre and the return fibre, causing firing.

7. An impact detector according to claim 5 or claim 6, characterised in that the said reflecting system is arranged at the periphery of the window in the device's homing device.

8. An impact detector according to claim 4, characterised in that the continuity of the pairs of optical outward and return fibres is ensured by transmission through an extenda ble antenna comprising reflecting surfaces, said antenna being extended by the action of a spring and being lockable in a position which ensures both the arming of the detector system, by the positioning of the said reflecting surfaces opposite the pairs of optical fibres, and the disalignment, on impact, of these elements, when the antenna is displaced in relation to the warhead, causing the interruption of the luminous flux and the firing of the explosive charge.

9. An impact detector according to claim 4, characterised in that the continuity of the pairs of optical outward and return fibres is ensured by transmission through an extendable antenna comprising reflecting surfaces, and in that the said antenna is fitted with a selfdestructing means which acts after detection of impact, wherein the arming of the detection system, by the positioning of the said reflecting surfaces opposite the pairs of optical fibres is brought about when the antenna is in the extended position at the same time as is effected the alignment of the pyrotechnic chain for firing the self-destructing means, and wherein the disalignment, on impact, of the optical fibres and the reflecting surfaces, when the antenna is displaced in relation to the warhead, cause an interruption of the luminous flux, the firing of the explosive charge and the destruction of the antenna.

10. An impact detector according to claim 9, characterised in that the means of selfdestruction, on impact, of the extendable antenna consist of a detonating fuse wound in a spiral inside the antenna.

11. An impact detector substantially as hereinbefore described with reference to the accompanying drawings.