GB2178144A - Manoeuvrable submunition - Google Patents

Abstract

A manoeuvrable submunition projectile 2 for combatting armoured target objects 4 in a target area 3 has a rigidly incorporated sensor 12 for the control of an aerodynamic adjusting system 5, such as flaps controlled in three-point operation or transverse impulse transmitters, which provides gyrating or wobbling motion during descent into the target area and then directional approach flight with end-phase course correction. For wobbling movement the longitudinal axis 10 is inclined relative to the vertical 6 for the large- area-spiral scanning of the target area 3. Upon detection of a target object 4, the projectile is changed- over to line-of-sight target homing. A threshold evaluation detects the migration of the target object 4' out of the central region of the sensor characteristic 13, in order by way of pulse-length control to carry out, if needed, course corrections. <IMAGE>

Description

SPECIFICATION Seeker-fuze submunition The invention relates to a submunition for combatting armoured target objects in a target area.

A submunition of such a kind, known as a terminally-guidable projectile, for the carrier rocket system MLRS III, is for example described in the journal DEFENSE ELECTRONICS, June 1984, page 102.

What is disadvantageous about this kind of submunition is the need for great technological expenditure and thus high cost by reason of the use of a seeker head which is movable relative to the submunition structure, in order, after ejection of the submunition from the carrier, to acquire, in the subsequent free-flight phase by strip-shaped scanning of the terrain transversely to the flight direction, a target object that is to be combatted, and then to home in thereon in the continuous guidance procedure.

Known from DE-OS 33 23 685 is a submunition, similar to said kind, which is ejected over the target area from its carrier, in order then to drop, suspended from the parachute, in decelerated fall into the target area and in so doing to scan this spirally for a target object that is to be combatted; and which has a parachute glide path control for the approach in a specific displacement direction to the target object detected. The requisite equipment determining the direction and end-phase control of the submunition movement is, however, similarly very expensive and complex.

In addition to this, the effect of a submunition descending on the parachute is restricted, because a glide path control of the parachute yields only a limited manoeuvrability and because finally the dropping movement decelerated by the parachute both assists defence possibilities against the submunition by firing from the target object, and causes drifting out of the target area by reason of air currents close to the ground.

In recognition of these factors, the problem underlying the invention is to design a submunition of said kind in such a way that, despite technologically more modest equipment compared with the terminally-guidable form of submunition, it still yields a good performance (effect in the target).

To solve this problem there is provided in accordance with the present invention a submunition which is characterised it is constructed as a dropped projectile having a structure-fast sensor and with an aerodynamic adjusting system for causing a gyrating or spirally wobbling movement during steep diving down into the target area as well as for sensor-guided end-phase course correction for direct approach flight to a detected target object.

Thus, the approach of the submunition, delivered by a carrier, to the target area is effected almost in free fall and thus most rapidly even from a great initial height, which reduces defence possibilities and risks of drift and makes possible the rapid search of the target area along a long path, thus of a large scanning region; with transition from a scanning movement of the projectile, gyrating (e.g.

wobbling so that at least part of its longitudinal axis moves in an arcuate manner, without the submunition necessarily turning or rotating about said axis) down into the target area, into a terminally-corrected target-homing glide path upon detection of a target, to be combatted, by means of a sensor incorporated rigidly into the structure of the submunition.

Thus, more especially the expenditure for a swingable seeker head, for direction findings in a space-fast system of coordinates, for a braking parachute and for continuously-working target-tracking control systems is obviated.

Instead, a direct functional coupling between the target-displacement evaluation and the aerodynamic adjusting system for the transition of the submunition out of its descent movement (in the manner of an object in an aeronautical spin) into the target-homing glide path can be provided; in which respect a threshold evaluation of the target displacement out of a reference region of the structure-fast sensor antenna characteristic opens up a three-point homing, simple in apparatus respects, of the aerodynamic adjusting system and thus an uncomplicatedly working control.

Transverse impulse transmitters can be provided for the adjusting system. More advantageously, however, control flaps are usable, which can at the same time perform glidingwing or guiding-fin functions upon the direct homing-in on the target.

The sensor for acquisition of a target object that is to be combatted can work actively or passively, in the infra-red region or in the millimetre-wave region, as known 'per se' for submunition seeker fuzes and described in more detail more especially in our own older Application P 35 02 186.1 dated 24th January 1985 for a specific example of realisation that is to be preferred. For the simple threshold evaluation of the target-object displacement from the longitudinal axis, in other words from the instantaneous orientation of the submunition, the sensor antenna characteristic in the target area can be subdivided into separately evaluable regions.The directional displacement of the target object sighted at out of the longitudinal axis of the can, however, also be determined by determined by beam deviation by means of a moving antenna auxiliary member (for example an asymmetrically rotated subreflector) or by a phase evaluation at a multielement antenna, as is known as such in the form of electronically swingable mechanically stationary millimetre-wave antennae.

In particular the invention provides a manoeuvrable seeker-fuze submunition, for combatting armoured target objects in a target area, which can be produced technologically in a less complex and thereby more economical manner than end-phase-guidable submunition rockets equipped with swivel seeker heads, but which yields a higher effect in the target than is achievable by means of a seeker-fuze submunition of a kind which incorporates a fixed sensor, is arranged to drop suspended from a parachute gyratingly into the target area and, even with expensively complex endphase-correction, has only a relatively restricted search region and is easy to combat and can easily be driven out of the target area by ground winds; the submunition of the invention being a diving-flight projectile having a rigidly incorporated sensor for the control of an aerodynamic adjusting system (preferably in a three-point manner of operation) by means of which, upon dropping from a great height above the target area the projectile is initially controlled into a wobbling movement with the longitudinal axis incided or inclined relative to the vertical for the large-area-spiral scanning of the target area; and on detection of a target object, the projectile is changed-over to approximately line-of-sight target homing, in which threshold evaluation detects the migration of the target object out the central region of the sensor characteristic, in order by way of pulse-length control to carry out, if needed, course corrections (preferably including a hitpoint shifting-forward for the proportional navi ration) upon homing-in on a moving target object.

Further developments and features, and alternatives thereto, and advantages of the invention will become apparent from the matter disclosed additionally in Claims 2 to 9, and the following description of a preferred example of an embodiment and use of submu nition in accordance with the present invention, which embodiment is described with ref erence to the accompanying diagrammatic drawings which are restricted to show that which is essential in a highly abstracted man ner and are not true to scale.In the draw ings: Figure 1 shows the kinematics of a submu nition in several consecutive operational phases; Figure 2 shows a highly simplified example of a submunition shown in Fig. 1; and Figure 3 shows a division of the cross-sectionai surface area of a sensor antenna charac teristic for the derivation of control information for a discontinuously end-phase-correctable submuntion in accordance with Fig. 2.

By means of a carrier 1 a number of sub munitions 2 is delivered over a target area 3, in which armoured target objects have been discovered or can be expected. The carrier 1 may be an artillery projectile or shell, a rocket or an aircraft. Preferably, however, within the framework of the present invention, a carrier 1 is used which is a munitions container which is released from an aircraft and which then automatically continues flying as far as over the target area. The submunitions 2 thereof are preferably projectiles which are profiled in a flow-favourable manner, so that these fly, with low drag in an aerodynamically stable manner which can also be influenced by means of simple adjusting systems 5, so that the missiles can be controlled, without any problems, in their flight path, particularly for end-phase homing-in on the detected target object 4.

Each submunition 2 is, after ejection from its carrier 1, to descend substantially in nosedive, in other words along a mean path approximately parallel to the perpendicular line 6, into the target area 3. To this extent it is basically immaterial in what orientation the submunitions 2 are arranged in the carrier 1 with respect to its substantially horizontal flight direction or respectively are ejected therefrom.

Since it is, however,-as will be explained in yet more detail hereinafter-expedient to initiate the nose-dive descent from the greatest possible height above the target area 3, it is advantageous, as taken into account in Fig. 1, to arrange the projectile-shaped submunitions 2 parallel to the flight direction 7 of their carrier 1 and to eject them with such incidence of their adjusting systems 5 that in a first functional phase I initially a submunition movement parallel to the flight direction 7 of the carrier 1 occurs; from which then a transition into a second functional phase II of further aerodynamic ascent ensues.When equilibrium between the gravitational force and the dy namic lift forces occurs, the path curve 8 of the submunition 2, flying on in an inertia-dictated manner after ejection from the carrier, has reached its apogee from which, with ap propriate constructional setting-up of the centre-of-gravity of the submunition with re spect to the dynamic point of application of its adjusting system 5, it changes round into the third functional phase Ill of the steep drop down into the target area 3. In the drawing it is not taken into account that, more especially in the case of a great initial velocity in the first phase, it can be expedient to abridge the flight path, parallel to the ground, as far as the transition into the third phase by aerodynamic braking means such as a parachute, a balloon or flaps.

A swing-in into the diving position is detectable on board the submunition 2 with the necessary accuracy by means of simple appa ratus, for instance through a pendulum system for determining the inclination of the submunition longitudinal axis 10 or by the cessation of the reaction force of a mass relative to the structure of the submunition 2 upon transition into the free fall. By means of a pre-programmed control 11 containing for example such a measuring system (see Fig. 2), now the adjusting system 5 is changed over in such a way that in a fourth functional phase IV in actual fact no free fall directly along the perpendicular line 6 occurs, but the submunition longitudinal axis 10 experiences, relative to this, a slight incidence along with control ling into a swivel movement.The submunition 2 thus described during its fourth functional phase in the movement of its longitudinal axis 10 approximately the generatrix of a conical surface and thereby does not descend linearly, but in a helically wobbling rotary motion, into the target area 5.

As a result of this aerodynamically caused precessive descent motion, the target-seeking sensor 12 describes, with its strongly bunched antenna characteristic 13, in the targetry area 3 a sequence of ranged side-byside arcs 14 which narrow spirally with the approach of the submunition 2 to the target area.These arcs lie all the more tightly close to one another, for the most gapless possible scanning of the target area 3 for a target object 4 that is to be combatted, the less is the wobble deflection of the submunition 2, in other words the less is its incidence relative to the perpendicular 6; and the region of the spirally scanned target area 3 has, by reason of the geometric factors with a given angle of incidence, an all the greater initial radius in the target area 3, the greater is the onset height of this wobbling target-seeking motion of the submunition 2 over the target area 3, which is why the highest possible apogee 9 is to be striven after.

During this spirally narrowing scanning of the target area 3 by means of the antenna characteristic 13 during the fourth functional phase, upon detection of a target object 4 that is to be combatted the detection signal processing means 15, connected subsequent to the sensor 12, initiates by way of the control 11 a re-orientation of the dynamic effect of the adjusting system 5 to the effect that the submunition 2 in a fifth functional phase V is deflected out of the wobbling motion into a gliding direction in which, in a sixth functional phase VI, it homes-in on the just detected target object 4 directly, in other words orientated along or parallel to the direction of the antenna characteristic 13 upon detection of the target object 4.In the simplified representation of the functional cycle sketch shown in Fig. 1 it is not taken into account that, on account of the finite time requirement for the change-over, in the fifth functional phase it can be expedient transiently to enlarge the detection angle of the characteristic 13 or respectively additionally to allow a superimposed wobbling motion of the submunition 2 so that the detected target object 4 is not lost again. Equally it is not expressed in the drawings that the submunition 2 in the sixth (and seventh) phase naturally needs a lift to compensate for the earth's attraction, in other words in actual fact moves along with transverse displacement relative to the line of sight to the target. A possible incidence of the longitudinal axis 10 relative to the direct direction of sight can readily be taken into consideration in the signal processing 15.

By reason of flow-dynamic transverse influences on the submunition 2 and/or by reason of proper motions of the target object 4 homed-in on, in the sixth functional phase the target can migrate relative to the longitudinal axis 10 of the submunition 2 into a shifted relative position of the target object 4'.This migration out of the centre of the antenna characteristic 13 is detected, by means of the sensor 12 and of the signal processing 15 connected subsequent to it, directionwise (in structure-fast coordinates) and coverted by way of the control 11 as well as the adjusting system 5 during a seventh functional phase VII into a discontinous control for the endphase course correction, for again accurate approaching of the migrated target object 4' in an eighth functional phase VIII. In the simplified sketch Fig. 1 it is not taken into account that further such functional phases VI 1-VIlI can follow, in order to carry out repeated end-phase corrections upon the homing-in on the target object 4'.

Upon impact of the submunition 2 on the target 4', or immediately before this, by means of the sensor 12 or of a separate triggering mechanism (not taken into account in the drawing), the submunition warhead 16 is detonated, which preferably has at least one jet-forming insert 17 for the destruction of the armouring of the target object 4'.

As indicated in simplified manner in Fig. 2, the adjusting system 5 consists for example of a simple flap arrangement. Upon the incidence thereof relative to the direction of the projectile longitudinal axis 10, an appropriate torque about the centre-of-gravity of the submunition 2 is initiated, in order to swing the longitudinal axis 10 out of the instantaneous spatial orientation. After return into the normal position parallel to the longitudinal axis 10, the flaps of the adjusting system again act as an aerodynamic gliding surface, so that the instantaneously assumed spatial orientation of the submunition longitudinal axis 10 is henceforth maintained as far as possible.However, also (not taken into consideration in the drawing) additionally separate gliding surfaces can be provided for this purpose. ( The adjusting system 5 for the end-phase correction of the flight direction of the submunition 2 upon the approach to the acquired target object 4' can also be realised in some other way, for example by transverse impulse generators for swivelling the projectile longitu dinal axis 10 about the centre-of-gravity of the submunition 2.The realisation of the adjusting system 5 by simple flaps has the advantage of being able to bring about both a pitching movement of the longitudinal axis 10- namely by incidence in the same direction- and a rotary motion-namely by flap incidence in opposite directions, and thus, by simple control cycles as a result of superimposition of these influences, being able to control the submunition 2 into the described spinning motion during the fourth functional phase, which is necessary in order, by means of the sensor 12 incorporated rigidly into the structure of the submunition 2, to carry out the spiral target-area scanning along the near-circular arcs 14.

A particularly simple electromechanical or electrofluid realisation possibility of the functional coupling between the control 11 and the adjusting system 5 emerges because no continuous operation of the control 11 is required, but a three-point or three-position operation (in other words enabling one deflection position on each side of the neutral or zero position) is sufficient. In the case of this, the adjusting system 5 is run only briefly into a defined second deflection position and, after performance of the desired manoeuvre of the submunition-in other words swivelling of its longitudinal axis 10 in space-this deflection is revoked again. The severity of the manoeuvre, in other words of the deflection, can then be influenced by a simple pulse length control.If the hinging of the adjusting system 5 to the structure of the submunition 2 is not realised in stable equilibrium, related to the aerodynamic effect of the incident flow, then it is sufficient, by means of the control 11, to cancel a locking in the basic position of the appropriate functional part of the adjusting system which is then transferred, by the aerodynamic effect, into its displaced position. Then, the control 11 again causes a return into the basic position. Conversely, the two-point operation with aerodynamically stable hinging of the adjusting system 5 makes possible the aerodynamically automaticaily ensuing return into the constructionally preset basic position, when a force applied by the control 11 for the deflection is switched off once more.

The three-point operation of the adjusting system 5 connected subsequent to the sensor 12 requires only a simple evaluation to recognise and compensate for a migatory movement of the target object 4'-4' once acquired and detected as to be combatted. For example, the cross-sectional surface area of the sensor antenna characteristic 13 (Fig. 3) can be subdivided into as many sectors a, surrounding in ring-arc-shaped manner a central region c, as different incidence directions can be triggered by means of the adjusting system 5. In the case of the biaxial-orthogonal adjusting system 5 shown in Fig. 2, the flaps of which can be displaced out of the neutralstationary position in two opposite directions, the four sectors al-ar and al'-ar' in the crosssectional area of the antenna characteristic 13 can be associated with the thereby possible incidence directions.So long as the detected and sighted-at target object 4 is still detected in the central region c of the characteristic 13, the flight direction (in other words the spatial orientation of the longitudinal axis 10) of the submunition 2 is maintained (sixth functional phase in Fig. 1). However, if the detected target object 4' migrates into one of the ring sectors a of the characteristic 13, a direct hit is no longer guaranteed.Therefore now-directly initiated from the relevant ring sector a (namely ar in the exemplified instance in accordance with Fig. 3)-by way of the control 11 that displacement or incidence of the adjusting system 5 is briefly triggered which, through a swivelling of the submunition longitudinal axis 10, precisely cancels this migatory movement in the cross-sectional area of the antenna characteristic 13 once more, thus by an end-phase course correction returns the target object 4', detected in its migratory movement, again into the central region c of the characteristic.

Controlled from the sensor 12, the incidence or displacement of the adjusting system 5 can now be cancelled again; if it is not from the very start, by reason of given geometric subordinations, linked with a pulse-length time control.

In Fig. 3 it is further taken into consideration that it can be expedient to define at least one ring-sector-shaped transitional region b in the antenna characteristic 13 between the central region c and the respectively radially linking outer region a. The timespan which a target object 4'-4' migrating from the central region c dwells in this intermediate region LH or which elapses until after exit from the central region c the entry into an outer ring region a is ascertained-is a measure of the migration speed and thus the line-of-sight rotary speed between the sensor 12 incorporated rigidly into the submunition and the detected target object. Derived from this measurement, the control 11 can then, as known 'per se', trigger an advance upon the discontinuous reorientation of the submunition direction of movement in the seventh functional phase; so that at least approximately a collision course in accordance with proportional navigation arises and accordingly a direct hit is to be expected even upon rapid fleeing motion of the detected target object 4.

Instead of the ring-sector evaluation of the sensor characteristic 13 in accordance with Fig. 3 also ray-shaped, or crossed lobes configurations can be provided, the oval cross-sections of which at the base of the target area 3 are evaluated subdivided into distance regions, in order to obtain displacement and migration information for the discontinuous end-phase flight correction of the submunition 2. In the drawing, to simplify the representation, it is also not taken into consideration that the incorporation of the sensor 12 can, in the interests of the target-homing relative to the flight position of the projectile, have an offset in the direction of the characteristic 13; and that, for the generation of aerodynamic lift and more rapid acquisition of the once detected target object, it can be expedient to equip the submunition 2 with a small cruising engine or booster which (along with the jettisoning or discarding of possible aerodynamic braking means) is started up upon the transition into the sixth functional phase.

Claims (10)

1. A manoeuvrable seeker-fuze submunition, for combatting armoured target objects in a target area, characterised in that it is constructed as a dropped projectile having a structure-fast sensor and with an aerodynamic adjusting system for causing a gyrating or wobbling movement during steep diving down into the target area as well as for sensorguided end-phase course correction for direct approach flight to a detected target object.

2. A submunition as claimed in Claim 1, wherein the adjusting system is discontinuously-working and can be transiently deflected in accordance with the instantaneous target displacement direction relative to the projectile longitudinal axis.

3. A submunition as claimed in Claim 2, wherein the adjusting system is controllable in three-point operation from the sensor.

4. A submunition as claimed in Claim 2 or 3, wherein the adjusting system has two orthogonally orientated pairs of control surfaces, of which at least the surfaces of one pair are also deflectable in opposite directions.

5. A submunition as claimed in any one of Claims 2 to 4, arranged to make a threshold evaluation, related to the effective direction of the adjusting system, of the displacement detected by the sensor of the target object relative to the projectile longitudinal axis.

6. A submunition as claimed in Claim 5, arranged to make an additional evaluation of the temporal target migration for an end-phase correction, approximated by proportional navigation, of the flight direction.

7. A submunition as claimed in any one of Claims 2 to 6, providing impulse-length control for the deflection of the adjusting system.

8. A submunition as claimed in any one of the preceding claims, equipped with an aerodynamic braking mechanism which is transiently effective within the functional phases between launch (e.g. carrier ejection) and targetobject detection.

9. A submunition as claimed in any one of the preceding claims, equipped with a propulsion unit which can be started up upon targetobject acquisition.

10. A submunition arranged to operate substantially as hereinbefore described with reference to Fig. 1 or Figs. 1 and 3; or constructed substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.