GB2142418A

GB2142418A - Cluster bombs

Info

Publication number: GB2142418A
Application number: GB08000002A
Authority: GB
Inventors: Geoffrey Brendan Wheaton; Donald George Merchant; John Stevenson Hunter; Michael Laurence Robinson; Jonathan Huntley Walla Shannon
Original assignee: Commonwealth of Australia
Current assignee: Commonwealth of Australia
Priority date: 1979-01-03
Filing date: 1980-01-03
Publication date: 1985-01-16
Also published as: AU5397179A; GB2142418B; GB2142419A; GB2142419B

Abstract

A cluster bomb in which a canister 1 contains a multiplicity of sub-munitions 34 guided in tubes 28 to be projected forwardly from the canister following separation of a nose 2 and deployment of a parachute tail 24 which retards the canister relative to the submunitions. A lanyard (19) extending from an aircraft serves both to activate a fuse associated with separation means for the nose 2 and to deploy the parachute. The projected sub-munitions are armed as a plate 39 is drawn rearwards by the drag of the air, the arming being delayed by engagement of a pin in a zig-zag groove 41. Fins 35 and grooves 36,37 in the submunitions contribute to aerodynamic instability of the submunitions so as to assist their spreading out over a wide area. <IMAGE>

Description

SPECIFICATION Cluster bomb Background of the invention This invention relates to cluster bomb units capable of dispensing sub-munitions to cover a wide area.

Cluster bomb units, which are generally referred to as CBU's provide a means of transporting on an aircraft large numbers of sub-munitions which can at will be dispensed from the CBU and scattered by various means so as to impact on the target over a wide area.

Known CBU either use aerodynamic forces to scatter the sub-munitions or they use explosive gas generators to provide forces at right angles to the ballistic trajectory of the CBU.

The known aerodynamically scattered CBU requires the weapon to be released from sufficient altitude to allow a safe separation distance to be established before sub-munitions are dispensed, and for sufficient lateral lift to be developed to cause scatter. The gas generator lateral dispersion devices also require altitude for safe separation, and the lateral spread is limited irrespective of speed or altitude of release by the power of the gas generator.

The specification of British Patent No. 1,402,281, MESSERSCHMIDT-BOLKOW-BLOHM GmbH has an an object to ensure a distinct lateral displacement of each individual body of a cluster, using the Magnus effect to obtain the desired lateral dispersion, and the device generally consists of a wide band of sheet metal divided by means of rupture ribs from which the armaments are thrown as the unit spins while it falls through the air, and the Magnus effect carries the individual unit away from the point at which they were released so that the desired scatter effect is obtained.

The specification of United States Letters Patent No. 3,611,931,THE UNITED STATES OF AMERICA, as represented by The Secretary of the Navy, relates to a sequential burst air drop cluster which has a number of sub-munitions in it and uses explosives to expel the munition modules from the system, the munition modules being acted on by a pusher plate to expel the modules due to pressure build-up following ignition of an explosive.

The specification of United States Letters Patent No.4,063,508, THE UNITED STATES OF AMERICA, as represented by The Secretary of the Air Force, relates to means for dispersing sub-munitions from a cluster weapon by utilising a foamed propellant, the system ensuring force dispersion of clustered sub-munitions when high pressure gas is generated rapidly and directly in the interstices of the cluster by a controlled detonation of a propellant mixture.

The specification of United States Letters Patent No.4,072,107, THE UNITED STATES OF AMERICA, as represented by the Secretary of the Army, relates to a sub-missile which breaks up into very fine fragments, the sub-missiles being utilised in large missiles and rockets where they are held in a canister so designed that the sub-missiles are dispersed through centrifugal force. This specification refers to control fins for slowing and rotating the canister in flight to ensure wide dispersion.

The specification of Australian Letters Patents Nos 121,871, 122,353 and 124,111, IMBER RESEARCH LIMITED of Great Britain, relate to means for holding and subsequently releasing bombs, flares or like devices held side by side by means of detachable elements which are separated by a common ignition device; No 121,871 showing the devices confined between a forward and a tail bulkhead joined by outwardly releasable canister forming sections.

The specification of Australian Letters Patent No.

144,476, GALANIS, has grenades held in a series of radially arranged barrels in a canisterto be fired therefrom into the path of aircraft by a central firing device.

Studies and trials carried out by the Applicant have shown that the deficiencies in pattern spread of the systems of the above types can generally be overcome by providing a particular aerodynamic dispersion method to scatter sub-munitions over a wide area when released at low aircraft altitude and yet still provide a safe separation distance from the parent aircraft.

It is thus an object of the present invention to provide a device which can be released from an aircraft into a trajectory which carries it accurately to the selected site.

It is a further object to so arrange the device that a safe separation between the aircraft and the device exists at the time of explosion.

It is a further object to achieve controlled release of sub-munitions from the device and the attainment of a required separation during flight of the submunitions.

It is a still further object to provide a means of achieving sub-munition scatter over the widest possible area from an aircraft flying at the lowest operational altitude.

The invention The CBU, the subject of this invention, is a sub-munition dispensing system which can be adapted to utilise various calibres and purposes of sub-munitions.

According to one form of the invention the sub-munition warhead is optimised for use against parked aircraft, but other uses will be apparent.

According to this invention, a canister appropriately designed and constructed to be carried externally on a high-speed low-level aircraft is used, and in this canister, set in a suitable material such as an insulating plastic foam, is a series of thin-walled tubes, each tube having a required number of sub-munitions housed therein.

The forward end of the canister has a bulkhead which is fitted to enclose munitions in the tubes and the bulkhead is restrained in position by releasable detents preferably in the form of radial petals which interlock with the canister outer skin, but releasable by a charge when the sub-munitions are to be dispersed. A bulkhead is fixed to the canister rear and to this bulkhead is fitted a tail which performs three functions: firstly in stablilising the CBU in ballistic flight, secondly in retarding the CBU when so commanded by a fuse, and thirdly by providing initial spin of the canister to assist sub-munition deployment.

The method consists in actuating the CBU at a selected time after release by a pilot by means of arming wires which activate a fuse to start the firing sequence which comprises releasing a parachute from a tail section of a canister which holds submunitions in longitudinal tubes in the canister, action of the parachute being to retard the flight of the CBU so that when a gas motor fires the detents to release a retaining bulkhead closing the forward ends of the tubes, the bulkhead is projected forwards ofthe canister, and the sub-munitions, because of the retarding effect of the parachute on the canister and their own momentum, eject from the tubes in a forward direction in a sequence controlled by counter air flow into the front of the tubes around the sub-munitions into the closed or restricted rear ends of the tubes, the sub-munitions being aided to deploy outwards by initial spin of the canister through parachute design.

Description ofthe drawings Figure 1 is a perspective view of a cluster bomb according to a preferred form of this invention.

Figure 2 is a perspective view showing the cluster bomb after release and with the parachute deployed to slow down the bomb while the aircraft continues its course until a safe distance is reached at which a propulsion charge is fired to project the forward bulkhead and, because of the retarding action of the parachute, cause the sub-munitions to leave the tubes and scatter generally in the direction of the trajectory.

Figure 3 is a longitudinal sectional view of the cluster bomb, but omitting the tail section.

Figure 4 is a section on line 4-4 of Figure 3 to show the arrangement of the radial petals which separate the nose part from the canister which includes the tubes carrying the sub-munitions.

Figure 5 is a somewhat diagrammatic forward end elevation of the canister showing the tubes which carry the munitions.

Figure 6 is a side elevation to a much larger scale than Figure 1, of one of the sub-munitions in the state when housed in the tube in the canister, the insert showing a further enlarged view of the shape of the end of the fins; and Figure 7 is a perspective view of the sub-munition, but showing it as in flight with the arming mechanism pulled out by aerodynamic drag to ready the sub-munition for explosion on impact.

Description of the preferred embodiment The canister 1 has on it a nose 2 and a tail 3, the nose 2 being locked to the canister 1 by means of a series of radially arranged petals 4 which are shaped so that when a cylinder 5 is projected forwardly by a gas charge from a piston 6 fitted to the front bulkhead 7, the detent ends 8 of the petals 4 are withdrawn from apertures in the canister 1 by pressure of the heel of the petals 9 against the wail 10 of the nose 2, the petals 4 having their inner ends connected by retaining bolts 11 to a flange 12 on the cylinder 5 so that when the cylinder 5 is projected forward by the gas pressure from the piston 6 the heel 9 acts as a fulcrum to move the detent ends 8 inwards to withdraw these ends from engagement with apertures in the canister 1, this action releasing the bulkhead 7 from the canister 1 so that it leaves the canister 1 and the sub-munitions can be deployed.

Forward movement of the cylinder 5 carries the forward part 14 of the nose forwardly, this being permitted by flexing a sealing diaphragm 15 connected between the wall of the nose 2 and a flange 16 secured to the cylinder 5, the part 14 being moved forwardly in relation to the nose 2 as shown in Figure 2 until such time as sufficient movement has occurred to operate the petals 4 to release the detent ends 8 on the petals from the canister 1, whereupon because of the retarding force on the canister 1, the nose section separates, again as shown in Figure 2.

Because the gas charge in the piston 6 moves the cylinder 5 rapidly forward, the entire front nose assembly is shocked forwardly, carrying the forward bulkhead 7 with it.

An arming and detonating fuse 18 is carried in that part 14 of the nose 2 and this has arming cables 19 extending from it which are connected to the aircraft so that arming of the cluster bomb occurs after separation of the bomb from the carrying aircraft, a lead 19 passing through the canister 1 to operate the tail 3 to deploy a parachute with the required delay after release of the cluster bomb from the aircraft has occurred.

The tail 3 comprises a frame 20 attached to a rear bulkhead 21 of the canister 1 and this supports a series of fins 22 and also includes parachute petals 23 which are arranged around the frame 20 and are hinged at their rear to the rear of the frame 20 so that they can be deployed by suitable pressure means when the cluster bomb is to commence the retarding action, but between the tail petals 23 are located parachute members 24 which are also fixed to the tail petals in such a manner that when the tail petals 23 open out about their rear hinges the parachute members 24 are deployed substantially as shown in Figure 2 and are held in this position by a series of cords 25 extending forward from the parachute sections and secured to the rear bulkhead 21, similar members 26 also limiting the rearward movement of the free ends of the tail petals 23 to ensure that the required drag is applied to the canister 1 after release from the aircraft. The parachute is shaped to cause the canister to rotate about its axis.

Within the canister 1 are a series of light tubes 28 which are held together by tie members 29 and are embedded in a plasticfoam material 30 which fills the space between the outer surfaces of the tubes 28 and the inner surface of the wall of the canister 1 whereby to hold the tubes firmly in position within the canister 1.

The sub-munitions 34 which are shown more particularly in Figure 6 and 7 comprise a body having a nose with a groove 36 circumferentially arranged just to the rear of the front end of the sub-munitions, the purpose of this being to provide the correct airflow about the sub-munitions after they are released from the tube.

Each sub-munition has a series of sub-calibre tail fins 35 arranged on an extension from the body 34 and arming of the sub-munition is by means of a sub-calibre plate 39 secured at the end of a movable arming slug 40, the plate 39 being so proportioned that it extends into the airstream between the tail fins 35 to be pulled out by the airstream at the appropriate time, but the outward movement of the arming slug 40 is retarded by an induced oscillatory motion in a time-delay device as it is pulled out, the arming slug having a zig-zag groove 41 formed in this member which engages an appropriate pin in the time-delay device. This is not shown as any standard time-delay device can be used.

Safety pins and other safety means are included in the sub-munition assembly, but these can take any usual or approved form and are not specifically shown herein.

The design of the sub-munitions 34 is such that they fit neatly into the tubes 28 supported in the canister 1 and when in place the rearmost submunition is lodged against the rear bulkhead 21 with the other sub-munitions stacked forwardly and with the most forward sub-munition loaded into position by resilient bosses 46 rearwardly projecting from the forward bulkhead 7 so that when the sub-munitions are assembled in the tubes they are firmly located and are of a dimension such that they move freely in the tube, but air flow past them is restricted. To ensure correct discharge of the sub-munitions the rear of the canister 1 is sealed by the bulkhead 21 so that the sub-munitions are successively released with progressive delay taking place to minimise collisions between the sub-munitions after they leave the tube.

The bulkhead 21 can of course have a controlled air flow into the rear of the tubes to further regulate the rate of discharge under inertia when the canister 1 is retarded by the parachute section.

The operation of the device is as follows.

The nose 2 at the forward end of the canister encloses a fuse 18 which controls the function of the CBU. When the CBU leaves the parent aircraft on the command of the pilot, the arming wires 19 activate it. Firstly the tail enabling assembly is activated to deploy its parachute, if so commanded. Secondly, a thermal battery is activated in the fuse 18 and a clock is started. If a third wire is pulled a full arming sequence is completed.

The clock causes electrically-fired gas motors or similar devices, not shown, in the tail to be connected to the battery after a preset time which allows the CBU to be clear of the aircraft. When the gas motors, or similar devices fire, the tail petals 22 are released into the airstream and since they are rear-hinged they open further deploying a parachute. The parachute, in a very short time, draws the CBU behind the aircraft so that sub-munitions may be released with acceptably low risk of damage to the parent aircraft should one accidentally detonate when released.

Sub-munitions are not released until a specified time has elapsed and the fuse has sensed an appropriate retardation/time history. The battery then fires a detonator in the fuse 18 which has been moved from a 'safe' position to an 'armed' position by retardation forces. This detonator ignites a gas generator charge in the axial cylinder 5 to which the fuse is attached. The piston 6 in the cylinder is attached to the front bulkhead 7 while the radial petals 4 have their inner ends attached to the cylinder.

As the gas in the cylinder 5 expands, the cylinder is forced forward. In doing so it moves the radial petals 4 which are so designed as to withdraw their ends 8 which interlocked with the canister 1. Thus, the front bulkhead 7 is no longer restrained to the canister.

When the cylinder 5 reaches the end of the travel of the cylinder 5/piston 6 combination, the piston head is restrained from leaving the cylinder. Because the fuse 18 and cylinder 5 combination has by this time attained sufficient momentum in the forward direction it continues forward, taking the piston 6 and attached bulkhead 7 with it. The proportions of the assembly and the gas generator charge are so chosen that the velocity of the assembly relative to the canister is sufficient to ensure that the assembly is well clear of the sub-munitions as they are released.

Since the sub-munitions 34 are now unrestrained in the forward direction the retardation force exerted by the open parachute 24 causes the canister 1 to be drawn away from the forward moving submunitions 34 and they emerge from their tubes into free air.

Because at the same time as retarding the CBU the parachute 24 has been imparting spin, the submunitions 34 are accelerated radially on emergence from the canister.

Because also no air is allowed to the rear of the sub-munitions 34 as they leave their tubes 28, the air pressure behind the sub-munitions becomes less as they move down the tube 28. This has the effect of progressively separating the sub-munitions 35 longitudinally.

Both these factors have the effect of reducing the mutual interference between sub-munitions and subsequent damage on emergence. Both factors are important to the efficient operation of the CBU.

Once the sub-munitions 34 are released into the airstream and are separated from each other, aerodynamic drag causes a plate 39 at the rear to withdraw an arming slug 40, providing the velocity is sufficient to overcome a safety spring, not shown.

The arming slug 40 is keyed to the sub-munition body via a zig-zag slot 41 and to an arming rotor42 via a parallel slot 43. Withdrawal of the slug 40 thus causes the rotorto oscillate in the manner of a clutter time-delay. At the end of the clutter delay the last track of the zig-zag rotates the rotor into the armed position where a detonator, lead and warhead are in line and a spring supported striker is freed. As this occurs the drag plate and slug fall away leaving the sub-munition under control of aerodynamic forces generated by its shape.

The sub-munition 34 has an aerodynamic stabilizer comprising radial fins 35 of sub-calibre span.

Airflow about the blunt nose is controlled by a shallow circumferential groove 36 which suppresses the effects of minor surface irregularities thereby sustaining symmetric flow conditions about the sub-munition body. In like manner a lip 37 atthe body-tail junction controls the air-flow about the finned stabiliser. With correctly chosen centre of gravity position the sub-munition will not fly stably on a normal ballistic trajectory but trims at incidence and develops lift in a random direction. Spin necessary for optimum scattering performance is imparted by a chamfer 38 at the trailing edge of each fin. The randomly directed lift causes the submunitions to scatter over an area dependent on height and velocity of the CBU at the moment of sub-munition release.

On impacting on atargetthewarhead is caused to detonate by any known means. A pre-fragmented warhead case can be used which fractures into fragments selected in size and weight to damage aircraft or other thin structures in the near vicinity.

Claims

1. A cluster bomb device comprising: a canister having a fixed bulkhead at the rear end and a releasable bulkhead at the forward end, a nose attached to the said forward bulkhead, and a tail projecting rearward from the said rear bulkhead characterised by deployable retarding means on the said tail, detent means on the said forward bulkhead engaging the said canister, means to withdraw the said detent means from engagement with the said canister, a nest of tubes within the said canister having their axes longitudinally arranged in the said canister, and adapted to each hold a series of sub-munitions in an end-to-end arrangement, and means to deploy the said retarding means and to release the said detent means whereby to jettison the said forward bulkhead and the said submunitions successively due to their rate of travel relative to the said retarding canister and its tubes.

2. A cluster bomb according to Claim 1 wherein the said detent means are radial petals supported by the said forward bulkhead to have detent ends withdrawably engaging the said canister.

3. A cluster bomb according to Claim 2 wherein the petals are actuated by a gas-operated piston and cylinder assembly of which one member is attached to the said forward bulkhead and the other member is attached to the said nose and arranged so that gas pressure propels the said nose forwardly to release the petals and carry the said bulkhead forward clear of the said canister.

4. A cluster bomb according to Claim 1,2 or 3 wherein the said nose carries a fuse arranged to successively arm and actuate the said cluster bomb when arming wires connected to the said fuse are actuated by the aircraft releasing the said cluster bomb.

5. A cluster bomb according to Claim 1 wherein the said retarding means on the said tail comprise petals hinged at their rear to the said tail to deploy outwardly when released, and wherein a parachute is activated when the said petals are deployed, whereby to apply a braking force to the said cluster bomb.

6. A cluster bomb according to Claim 5 wherein the said petals andlor parachute are arranged to induce rotation of the said cluster bomb about its longitudinal axis when in flight whereby to accelerate the said munitions radially on emergence from the said tubes.

7. A cluster bomb according to any preceding claim wherein the said sub-munitions carried in the said tubes each comprise a body having a tail section with sub-calibre fins, and wherein an arming slug is axially disposed in the said tail and has a sub-calibre arming plate normally positioned adjacent to the said tail but movable rearwardly by air pressure to arm the said sub-munition during flight and whereby to prevent arming when a series of the said sub-munitions are held in end-to-end contact in a said tube.

8. A sub-munition according to Claim 7 wherein the said arming slug is provided with a zig-zag deformation to oscillate a rotor to introduce a time-delay in arming.

9. Sub-munitions for a cluster bomb adapted to be ejected successively from tubes in a canister aligned with the axial direction of flight of the canister when released from an aircraft, characterised in that each sub-munition comprises a body having a tail section with sub-calibre fins, and by an arming slug which is extendable from the rear of the said body and carries a sub-calibre arming plate projecting into an airstream flowing between the said fins when the said sub-munition is forwardly released from a said tube to move back the said slug to arm the said sub-munition, said sub-munition having its centre of gravity so positioned that the sub-munition will notfly stably on a normal ballistic trajectory but trims at incidence to the ballistic trajectory to develop lift in a random direction.

10. The method of dispersing sub-muntions from a cluster bomb which comprises: (a) inserting a plurality of sub-munitions end-toend in each of a series of tubes arranged longitudinally in a canister arranged to be dropped from an aircraft with its axis aligned generally with the direction of flight; (b) restraining the said sub-munitions in the said tubes by a rear bulkhead fixed to the said canister and a forward bulkhead supported by, but releasable from the said canister; (c) releasing the said canister from the aircraft and arming a sequence control fuse and timer mechanisms in the said canister by such release; (d) progressively retarding the flight of the said canister by deploying air braking means on the said canister; and (e) releasing the front bulkhead by pressure means arranged to eject it forwardly relative to the retarding canister to thereby release the said sub-munitions from the tubes in the canister because of their momentum relative to the progressively retarding canister.

11. The method of Claim 10 wherein the release of the front bulkhead is effected by gas pressure means ejecting a nose on the said cluster bomb forcibly forward to release and carry with it the said forward bulkhead, whereby to release the said sub-munitions from the said tubes by their forward momentum relative to the retarding canister and tubes.

12. The method of Claim 10 or 11 wherein the said tubes are at least partly sealed at the rear by the said bulkhead whereby the sub-munitions are separated in space as they move down the tubes by progressively reduced air pressure behind them.

13. The method of Claim 10,11 or 12 wherein the said canister is spun by the said retarding means to accelerate the said sub-munitions radially on emergence from the said tubes.

14. The method of Claim 10,11 or 12 wherein the sub-munitions are urged laterally by selecting the position of the centre of gravity and by choosing their shape to control air flow over them such that they are positioned at an angle to the direction of flight to develop lift in a random direction.

15 ih's.method of any preceding claim wherein arming slugs on each sub-munition are held in an unarmed position by arranging the sub-munitions to fill the said tubes to prevent withdrawal of the arming slugs, and arming the said sub-munitions by repositioning the said arming slug by air flow over the said arming slug as the sub-munitions separate on being successively ejected from the said tubes.

16. A cluster bomb substantially as hereinbefore described with reference to Figures 1 to 7 of the accompanying drawings.

17. A method of dispensing sub-munitions from a cluster bomb, substantially as hereinbefore de scribed with reference to the accompanying draw ings.

17. A sub-munition for a cluster bomb, substantially as hereinbefore described with reference to Figures 6 and 7 of the accompanying drawings.

18. A method of dispensing sub-munitions from a cluster bomb, substantially as hereinbefore described with reference to the accompanying drawings.

Superseded claims 5,7,8,9,16,17,18 New or amended claims:- 5,7,8,9,16,17

5. A cluster bomb according to Claim 1 wherein the said retarding means on the said tail comprise petals hinged at their rearto the said tail to deploy outwardly when released, and wherein a parachute is provided being arranged to be activated when the said petals are deployed, whereby to apply a braking force to the said cluster bomb.

7. A cluster bomb according to any preceding claim wherein sub-munitions carried in the said tubes each comprise a body having a tail section with sub-calibre fins, and wherein an arming slug is axially disposed in the said tail section and has a sub-calibre arming plate normally positioned adjacent to the said tail but movable rearwardly by air pressure to arm the said sub-munition during flight and whereby to prevent arming when a series of the said sub-munitions are held in end-to-end contact in a said tube.

8. A cluster bomb according to claim 7 wherein the said arming slug is provided with a zig-zag deformation to oscillate a rotor to introduce a time-delay in arming.

9. A cluster bomb according to claims 7 or 8, characterised in that the arming slug is extendable from the rear of the said body and the arming plate is arranged to project into an airstream flowing be tween the said fins when the said sub-munition is forwardly released from a said tube to move back the said slug to arm the said sub-munition, said sub-munition having its centre of gravity so posi tioned that the sub-munition will not fly stably on a normal ballistic trajectory but trims at incidence to the ballistic trajectory to develop lift in a random direction.