US20080047450A1

US20080047450A1 - Classified

Info

Publication number: US20080047450A1
Application number: US10/469,975
Authority: US
Inventors: Peter Lockhart
Original assignee: Roke Manor Research Ltd
Current assignee: Roke Manor Research Ltd
Priority date: 2002-12-19
Filing date: 2003-12-16
Publication date: 2008-02-28

Abstract

A munition includes a winding the configuration of which is changed as the munition detonates. The coil is seeded with a current and as the configuration of the winding changes a large em pulse is generated. Detection of the pulse can indicate whether or not the explosion is satisfactory and that the target is this destroyed. This avoids having to unnecessarily attack the target again.

Description

This invention relates to apparatus and a method for determining the operation of a munition and is particularly, but not exclusively, applicable to a munition designed to explode in a position where it is obscured from view.
Airpower is widely recognised as a significant factor in modern warfare. Recent conflicts such as the Gulf war and Kosovo have utilised airpower to a very significant extent. Modern anti-aircraft weapons however cause pilots to attack targets from a high or very low altitude in order to avoid being shot down. A consequence of this is that very many more targets are reported as destroyed than are actually destroyed. Whilst recognisance satellites and aircraft can later confirm whether or not the target has been destroyed this is not always possible. A type of target that poses particular difficulty is that of the hardened underground bunker. These are particularly important targets for the following reasons.
Hardened bunkers are used to house important assets such as command and control infrastructure or chemical or other weaponry. The effort required to construct such bunkers shows the importance of their contents. By successfully destroying the contents of the bunker the effects are much more significant than for example destroying one armoured vehicle. Accordingly, significant effort is required to mount a mission to attack such a target. It is important to note that the mission will involve not just one aircraft dropping a bunker-destroying bomb. The mission will require a host of other aircraft from re-fuelling tankers, electronic countermeasure and defence system suppression aircraft and air defence fighters. In essence a single attack may involve the use of dozens of people and military assets and expose a number of personnel to possible harm. Each attack is therefore a significant undertaking and it is very important to be able to determine the success of the attack.
In the Gulf war a rather crude way of determining the success of a bunker attack involved the attacking aircraft aircrew monitoring for the sight of a secondary explosion. A secondary explosion is caused by the contents of the bunker being caused to explode by the explosion of the aircraft's munition. This approach is unsatisfactory. Firstly, it is possible for the contents of a bunker to be destroyed but for there to be no secondary explosion. For example, a bunker housing communications equipment may not give rise to a perceivable secondary explosion. Secondly, a bunker will have many metres of reinforced concrete which may to a significant extent contain the secondary explosion. Of course, the bunker may also be empty. The unfortunate consequence of this is that the mission may be re-planned and carried out again when there is no need to do so.
A further problem is the use of countermeasures to fool attacking aircraft that the mission has been successful by for example causing a decoy secondary explosion or by simulating damage to be viewed by later reconnaissance.
It is an object of the invention to provide an apparatus and a method which alleviates these problems.
According to the invention there is provided in a first aspect apparatus as set forth in claim 1 and in a second aspect a method as set forth in claim 15.

A specific embodiment of the invention will now be described, by way of example only, with reference to the drawings in which:

FIGS. 1 and 2 show a weapons system in accordance with the invention being used to attack a hardened bunker;

FIG. 3 shows the weapons system of FIGS. 1 and 2 in block diagram form; and

FIG. 4 shows a munition used in the weapons system its operation.

With reference to FIG. 1, a weapons system 1 used to attack a hardened bunker 2 comprises a launching platform in this case an aircraft 3, munitions 4, 5 and a management system 6 mounted on the aircraft which includes an antenna 7. The munitions will be described in greater detail later but they use a combination of ballistic energy and a first penetrating charge to propel a secondary charge into the bunker cavity 7.
The bunker itself is formed of layers of steel mesh reinforced concrete 8. Each layer will have a different constitution to resist penetration. The thickness of these layers will be a number of metres. The bunker cavity 7 holds munitions 9 and personnel 10 and the bunker is primarily located below the ground surface 11.
FIG. 2 shows the bunker moments after impact which shows that the munition has entered the bunker cavity 7 having penetrated the layers of concrete 8 but just prior to detonation of the second charge.
Having now described the overall system and, in a broad way, the manner in which it is used to attack a target, a more detailed description of the weapons system will be given by reference to FIG. 3. The weapons system has two major components. A first of these is the aircraft borne management system 6 and the second being the munition borne components 12.
The management system comprises the antenna 7 operably coupled to a receiver section 13. The receiver section is in turn coupled to a processor 14 and the processor to a targeting system 15. The targeting system is operated by the pilot of the aircraft 3 to allocate and direct munitions to targets. The way in which the system directs munitions to the target may be by an optical fibre link, a laser illuminator, radio link or by other means or a combination of these. The antenna and receiver are configured to receive and analyses an electromagnetic pulse produced by the munition as it detonates. The manner in which this pulse is produced will be described in detail later.
The munition borne components have a first set associated with a primary charge on the munition which is used to penetrate the secondary charge into the bunker. It comprises a processor 16 operably coupled to a fuse sensor 17, a detonator driver 18 under the control of the processor to drive an electrically activated detonator 19. The fuse sensor 17 registers the impact of the munition on the outer layer of the bunker 2 and the sensed output is passed to the processor 16. If the sensed impact indicates a hard structure the driver is activated and the detonator 19 triggered to explode the primary charge. If the impact is below a threshold the processor may determine that the impact indicates a softer layer which may be penetrated using the munitions ballistic energy. Upon hitting a harder layer the threshold may be crossed and the detonator triggered.
The triggering of the primary charge then forces the secondary charge down through the layers to penetrate into the bunker cavity 7. The secondary system then comes into play. The secondary system comprises a fuse sensor 20 operably coupled to a processor 21. The processor 21 is in turn coupled to a coil driver 22. The coil driver is coupled in turn to a coil 23 which will be described a greater detail later. The processor 21 is also coupled to a detonator driver 24 which is in turn used to trigger a detonator 25 to set off the secondary charge.
The fuse sensor 20 registers the penetration of the layers as a series of decelerations. The processor 21 monitors the output of the sensor to determine the appropriate time to trigger the secondary charge. This may be determined according to information known about the composition of the target. In this specific embodiment the charge is triggered after it has entered the cavity but for other targets it may be triggered within the target layers. The triggering is caused by detecting no further decelerations within a certain time frame. This will occur once the munition has entered the free space of the cavity 7. The processor 21 firstly energises the coil 23 via the driver 22 and then the detonator 25 via the driver 24 to initiate the secondary charge.
The configuration of the coil, its function and relationship with the secondary charge and its interaction with the rest of the weapons system to register a successful explosion will now be described with reference to FIG. 4.
FIG. 4 a to 4 c shows the secondary charge in a sequence in the milliseconds following detonation. Accordingly, the reference numerals will signify the same component through the figures. The secondary charge 26 is generally cylindrical in configuration with the figures showing a longitudinal section. It includes an axially extending core of high explosive 27 such as C4. At one end of the explosive core 27 is located a detonator and a shaped charge or explosive lens used to produce when initiated a plane explosive shock wave which travels left to right in the explosive core to cause detonation. (The progression of the explosive event is shown in the FIGS. 4 b and c.) The explosive core is located within a copper armature tube 29 the purpose of which will be later described. A cylindrical stator winding 30 of copper wire is located to be coaxial with the armature tube. and spaced apart. The winding 30 is supported by a cylindrical dielectric jacket 31 which prevents adjacent turns of the winding 30 from contacting each other. The coil 30 is provided with a stator-input ring 32 and a stator output ring 33. These are connected to the coil and are held apart from the armature tube 29 by annular insulator blocks 34 and 35. It should be noted that the inwardly directed surface of the winding 30 and the outwardly directed surface of the armature tube 29 are held in spaced apart relationship but the space therebetween is empty apart from the supporting insulating blocks 34.
During the initiation phase when the secondary charge is determined as having entered the bunker cavity 7 a seed current is set up in the stator winding 30 (the coil 23 referred to in FIG. 3) and the explosive lens initiated (the detonator 25 of FIG. 25). This initiates the explosive core 27 and a detonation wave progresses left to right in the figure. This causes a rapid expansion of the copper tube 29 radially outwards in the manner shown in FIGS. 4 b and c. This causes a progressive although exceedingly rapid bringing into contact of the tube 29 and the windings 30. The tube 29 shorts adjacent windings causing the seed current to be progressively compressed into the remaining coils amplifying the resultant magnetic field many times over. The more rapid this expansion is the higher frequency component the resultant magnetic field. Accordingly, a resultant electromagnetic pulse is produced which may be detected and used to determine how much of the explosive core 27 has detonated. A pulse of high energy will indicate a complete explosion whereas a lower energy pulse will indicate that the core has not detonated explosively but has rather burnt. Levels in between will indicate partial explosion.
The antenna 7 of the aircraft 3 will detect the pulse and pass the result interpreted by the receiver 13 and the processor 14 to the targeting system 15. In the event that the pulse does not meet the predetermined criteria for a successful attack, the targeting system alerts the pilot (or other systems such as a recording system). In this embodiment the targeting system allocates the other dropped munition 4 to this bunker target.
In the event that the pulse meets the criterion for a successful attack, the munition 4 is reallocated to another target and directed accordingly. The success of the attack is notified to the pilot and also recorded for later post mission analysis.
It is may be also possible to modulate the resultant impulse or impulses, to indicate other parameters of the mission, such as the number of voids counted.

Claims

1. Apparatus for producing an indication of the detonation of a munition comprising a winding for, in use, carrying a current which winding being arranged to change configuration by the detonation of the munition thus causing a variation in the field produced by the current and to produce thereby the indication, wherein at least one resultant impulse is modulated to indicate at least one other mission parameter.

2. Apparatus as claimed in claim 1 wherein the configuration of the winding is one in which the number of electrically distinct windings is varied.

3. Apparatus as claimed in claim 2 wherein windings are shorted to change the configuration.

4. Apparatus as claimed in claim 3 wherein an armature is driven into contact with the winding by the detonation of the munition to change the configuration of the winding by shorting at least some of the windings.

5. Apparatus as claimed in claim 4 wherein the armature is arranged about an explosive core to be driven thereby into contact with the winding.

6. Apparatus as claimed in claim 5 wherein the winding, a stator and the explosive are co-axial.

7. Apparatus as claimed in claim 6 wherein the armature and the winding are maintained apart at least in part by an electrically insulting material.

8. Apparatus as claimed in claim 1 comprising a detector for detecting the occurrence of an electromagnetic pules produced in use by the winding.

9. Apparatus as claimed in claim 8 wherein the detector determines the occurrence of satisfactory detonation of the munition by reference to the characteristics of the pulse.

10. Apparatus as claimed in claim 9 wherein the characteristics include magnitude.

11. Apparatus as claimed in claim 8 wherein the detector is located at an aircraft.

12. (canceled)

13. A munition including apparatus as claimed in any one of claims 1 to 7.

14. An aircraft including apparatus as claimed in claim 1.

15. A method for producing an indication of the detonation of a munition comprising providing a winding the configuration of which is varied by detonation of the munition; providing a current in the winding and detecting an electromagnetic pulse produced by the winding as its configuration varies; and modulating at least one resultant impulse to indicate at least one other mission parameter.

16. A method as claimed in claim 15 wherein a characteristic of the pulse is used to determine where a detonation criterion has been met.

17. A method as claimed in claim 16 wherein the characteristic includes the magnitude of the pulse.

18. (canceled)