GB2232748A - Remotely controllable aircraft - Google Patents

Description

1 1 1 REMOTELY CONTROLLABLE AIRCRAFT This invention relates to an aircraft

which is remotely controllable, and in particular to an aircraft which is controllable from a control station for the reconnaissance of sea targets.

The fighting of enemy marine surface forces requires sufficiently clear reconnaissance results. These can be obtained by means of manned aircraft equipped with electro-optical apparatus. In this connection, the aircraf t have to f ly so near to the enemy that they themselves are greatly endangered such that today in general - apart from submarine combat - one attempts to obtain reconnaissance results over relatively large distances by land-, ship-, or air-borne radar apparatus. Such radar reconnaissance has three essential disadvantages. Firstly, the radar operates actively such that the enemy is aware of the reconnaissance attempt and can thus take suitable countermeasures. Secondly, radar reconnaissance in war is suspected to be preventable by jamming devices (broadband), at least in such restricted areas as the Baltic Sea, for example, such that reconnaissance results may be obtained only with difficulty. Thirdly, enemy ship targets are reproduced by radar only as blips, which have to be interpreted. It 1 2 is, therefore, not possible to decide on the basis of the blip alone, for example, whether the ship is a friendly one or an enemy one, a warship or commercial ship, a f erry, a hydrof oil, hovercraf t r f ishing vessel and so on.

Likewise, classification of the ship type is impossible, let alone identification of the ship itself. On the basis of such reconnaissance results it is, as a result, difficult to decide whether or not to use marine-target missiles.

If, however, conf lict is to be initiated, then this is suspected seldom to be successful in the case of missiles, since in general such missiles have an active radar homing head which reveals its f inal approach to the ship/boat to be attacked at the latest when the homing head has detected and controlled the target. The range of protective measures of the target attacked is diverse, and ranges f rom reactively produced dummy targets (for example window or chaf f clouds) to reactive, displaced interference or response- jammers which divert the attacking missile, even if it is equipped with a home-onjam ability, to the active adjacent region defence weapons which can shoot down the attacking missile before it hits the target. Independently of these difficulties, it is not possible to determine in advance which target the missile is to attack when it is a case of several t 1 3 vessels travelling as a unit.

This leads to the fact that, where possible, the missile engages a less important target in the unit simply because it has appeared first from the radar horizon of the radar homing head of the missile, whilst an important target which is in the near vicinity remains unattacked. Moreover, when the conceivable protective measures of the target have stopped for whatever reason, the missile hits the target in the radar centre of gravity and in general, depending on the attack bearing, this centre of gravity is never located where the target vehicle is most sensitive.

The effect produced on the target by the missile warhead can thus be so slight that, even af ter more than one missile hit, the target ship still has a certain degree of manoeuvrability and fighting strength.

It is an object of the invention to provide a means of observing marine targets as accurately as possible and where possible in an unobserved manner.

According to the invention, there is provided a small unmanned aircraft which is remotely controllable from a control station for observing sea targets, the aircraft I& 4 having a low radar reflection area (RCS), and being operable to fly over a sea area to be monitored at a low velocity, and, during the f light, to record images and transfer them to a control station where the targets can be identified and selected. one embodiment of the invention is operable to attack marine targets, by f lying as far as the vicinity of the marine target to be attacked, wherein the aircraft itself or a warhead with a booster is then accelerated to a high velocity and hits the marine target from above at a pre-determined point. Such a device can be designed so that its effect on the target is so great that the target can be put out of action in a single attack. Preferred features in accordance with the invention are set out in the dependent claims.

Preferably, the aircraft flys over the area of sea to be monitored on the basis of images transferred to the control station and displayed there, and control signals transferred from the control station.

Plying height and velocity may vary according to orders and the weather situation until the anticipated target area is reached. In accordance with the invention, the aircraft is designed to fly very slowly - after having reached the zone of use more quickly -, as a result of v 1 which it can only be located by radar aircraft with great difficulty. Typical velocities lie below 50 metres per second, preferably below 30 metres per second.

In the preferred embodiment, the viewing direction and a zoom device of a stabilised image unit installed in the aircraft, in particular a thermal imaging device, which operates passively in the far infra-red range (from 8 to 14 gm). can be selected by the operator in the control station by giving the aircraft the corresponding command. In this connection, data may be transferred along a radio link maintained between a transceiver antenna of the control station and a transceiver antenna of the aircraft. In order to make this possible when the location of the aircraft varies, the antenna can be controlled either such that they are mechanically rotatable or manipulable, or electrically variable.

The radio link allows an exchange of data- between an aircraf t and a control station which cannot, in practice.

be detected by the enemy and inter alia cannot, therefore. also be interfered with.

The aircraft is preferably constructed in such a way, that seen from the direction of threat, it has radar reflected cross-section of 0.001 to 0.01 M2. Since the 6 flying velocity can preferably be set at values below 30 ms-1, it would not be possible to differentiate between this aircraft and seabirds, such as gulls for example, even with the most modern radar apparatus. Since the infra-red radiation is also very low and the thermal imaging device in the aircraft operates passively, the enemy has no possibility of establishing that he has been observed, provided the aircraft does not fly so close to the marine target that it can in turn differentiate in an optronic manner between the aircraft and a seagull. But objects on the surface of the water can be detected, classified and even identified as sea targets by the operator in the control station far beyond this minimum distance, since these marine targets are larger by orders of magnitude than the aircraft itself, owing to the variably adjustable magnification of the infra-red optics in the aircraft. Since the flying height can be set to the prevailing lower cloud limit and the sea targets can be picked up passively by the thermal image aircraft in the 8 - 14 gm wavelength range (far infra-red), this type of secret observation can be used day and night in practically any weather and thus represents a considerable advance in terms of weapon technology with respect to all other methods used hitherto in sea patrol.

The reconnaissance data of the control station exist in f 0 7 real time and can be transferred to any user. Since the range of the aircraft can be up to 400 km and more depending on flying height,, the control station may be located together with its transceiver unit on land for reconnaissance of restricted sea areas such as the Baltic sea, for example, as can the launching apparatus for the aircraft. If an additional relay station is provided on one's own territory in the vicinity of the control station, for example in a helicopter which can climb to greater heights. the reconnaissance range of the aircraft increases even further. In this connection it is conceivable that particular aircraft are provided' only for reconnaissance and not for conflict, which would considerably increase the duration of time the reconnaissance aircraft remains over the sea area to be observed. It is likewise conceivable for combat then to be assumed by other marine warfare means.

When combat targets are selected on the basis of the reconnaissance images present in the control station, additional aircraft are sent to the corresponding sea area as required and each aircraft flies towards its allocated target. In this connection a velocity which is as low as possible should firstly be selected which is also associated with very low infrared radiation. At the same time the aircraft reaches a flying height such t 8 that the target can still be discerned well in the thermal image and the contour resolved to a satisfactory degree f rom above. Subsequently. either the point on the deck of the target ship at which the submunition is to penetrate is transferred by the control station to the aircraft by a command or the control station simply transmits the ship type to the aircraft which then determines the point itself on the basis of its own data.

Furthermore, for additional camouflage, the approach path can be selected in such a way that, viewed from the sea target, the aircraft comes as far as possible "out of the sun" if the time of day and weather so permit. From a given point in time from which the camouflage as a seagull or the like can no longer be maintained, and it is observed that the enemy- is taking counter-measures, the aircraft or a submunition ejected by it falls as steeply and rapidly as possible onto the target (for instance by ignition of a booster).

It is likewise possible f or the aircraft to f ly to a point from which the weapon can be accelerated as vertically as possible downwards in order to penetrate the pre-determined point on the deck of the marine target. Owing to its high kinetic energy and the special shaping of its warhead, which preferably has a large 4 A 9 length-to-diameter ratio, a pointed shape, and is made of carbon steel or a like material, it is possible to penetrate a plurality of decks or even the bottom of the target. The warhead is then detonated at the predetermined point which is most sensitive for each particular ship type, whether it be below or inside the sea target, by means of decelerometers in the form of sensors and special timing circuits.

These points may be at an "ideal distance" midships below the keel line, on the shaftt on the propeller, in the operations control room, in the drive assembly (for example, a gas turbine) and so on. At these points a sea target can be put completely out of action by an is explosive charge of as little as 10 kg.

By means of the proposed remote controlled aircraft it is possible to monitor and reconnoitre restricted sea areas, such as the Baltic Sea, as well as to fight sea targets from land with the minimum of personnel and cost compared with to current methods. Moreover. personnel are not required for reconnaissance and conflict in the actual sea areas threatened by the enemy, so that endangering of personnel is also minimal compared with current reconnaissance and fighting methods.

C

Claims (16)

1. An unmanned aircraft which is remotely controllable f rom a control station f or observing sea targets. the aircraft having a low radar reflection area (RCS), and being operable to fly over a sea area to be monitored at a low velocity, and, during the f light, to record images and trans f er them to a control station where the targets can be identified and selected.

2. An aircraft according to claim 1, operable to attack marine targets. to f ly as f ar as the vicinity of the -marine target to be attacked, wherein the aircraft itself or a warhead with a booster is accelerated to a high velocity and hits the marine target f rom above at a predetermined point.

3. An aircraft according to any preceding claim, characterised by a thermal imaging device operable passively in the far inf ra-red range (8 14 gm wavelength) as the image recorder.

An aircraft according to claim 2, wherein the aircraft itself or the warhead has such high kinetic energy that it penetrates the deck of the marine target and detonates at a predetermined location, for example under the keel line, on the propeller, in the operations control room, or at some other pre-determined point on the marine target.

5. An aircraft according to any preceding claim. having a propulsion unit, for example, a propeller motor, settable such that the flying velocity drops to values below 30 ms-1.

6. An aircraft according to any preceding claim, having a radar reflection cross-section (RCS) of less than 0.01 m2 viewed from the front and obliquely from below.

7.

An aircraft according to claim 3, wherein the incorporated thermal imaging device is provided with a stabiliser and comprises a variable optical system, which makes it possible to view.forwards, downwards and laterally. and which has a variable focal length with an associated zoom effect.

8. An aircraft according to any preceding claim, operable to transfer data by means of a directional antenna or by means of a plurality of antennae. the direction of radiation being selected by controlling 12 the antennae electrically.

9.

An aircraft according to any of claims 1 to 7, having an antenna for data transfer mounted on the upper side of the aircraf t in such a way that the directivity of the antenna can be adjusted by mechanical alterations such as rotating or tilting.

10. An aircraft according to any preceding claim, arranged such that data transfer is radiated in such a direction that nothing thereof can be observed at the assumed enemy location or that the data is only transferred at certain distances in the form of brief pulses which the enemy can only pick up with difficulty.

An aircraft according to any of claims 2 to 10, operable to be controlled until it is above the target, then to nose-dive and to ignite a booster on a submunition.

12. An aircraft according to any of claims 2 to 11, operable such that the submunition penetrates the deck of the target at a point selected by the 25 control station on the basis of the target image.

13.

is 13 An aircraft according to any of claims 2 to 12, operable such that, on the command from the control station, the submunition penetrates f urther decks and if necessary the ship bottom after penetrating the upper deck in order to detonate at the point which is most sensitive for the target in question.

14. An aircraft according to any of claims 2 to 12, arranged such that the most sensitive points of the marine targets in each case are programmed in a f ixed manner and the corresponding parameters for the submunition are automatically adjusted as soon as the selection and identity of the marine target has been established by the control station and transferred to the aircraft.

15. A marine attack system including according to any preceding claim.

an aircraft

16. An unmanned aircraft constructed and arranged substantially as herein described.

Published 1990 at The Patent Office. State House. 66'71 High Holborn. London WCI R 4TP. Further copies maybe obtained from The Patent OfficeSales Branch, St Maxy Cray, Orpington, Rent BR5 3RD. printed by Multiplex techniques RAL St Mary Cray, Kent, Con. 1/67