GB2205798A - Unmanned aircraft - Google Patents

Abstract

An unmanned aircraft (UMA) 10 has a flexible, stowable wing 11 of, for example, the rogallo type so transported to its intended location by a second air vehicle such as, for example, a rocket 31 with nose cone 30 or a VSTOL aircraft, the UMA 10 having its wing in the stowed position and deployed after release from the second air vehicle. It is envisaged that the UMA may be employed in a number of roles including, for example, target practice, surveillance, and deploying decoys or electronic counter-measures (ECM) equipment. <IMAGE>

Description

IKPROVEMENTS IN OR RELATING TO UNMANNED AIRCRAFT The present invention relates to unmanned and/or remotely piloted aircraft (UCi).

UMA's are used for various tasks including target practice, reconnaisance, deploying electronic counter measures (etc) payloads, communications relays. Most ZA's have been of the conventional fixed wing type. When deployed by ground based forces UMA's of the fixed wing type may be recovered relatively easily due to space available. However, use of UMA's for naval operations pose several problems especially with recovery thereof.

UMA's used in military or naval operations are preferably reusable. From a naval operations point of view the operation of a W4A takes place from a very confined space especially in the case of smaller ships such as frigates. Use of a U,\tS must offer both a cost and performance effective increase in the overall defensive/offensive capability and form an integral part of the ships weapons system. It must not place unacceptable constraints on the other component parts of the total ship system.

A further limitation of the fixed wing type of UMA when being operated from a relatively small warship is that of the performance of the UMA. Due to the necessarily small size of such an air vehicle the range, height capability and loiter time may be unacceptably limited. This is especially important in the ship defence context.

One method of placing a UMA at a particular height and position other than flying it under its own power from a conventional catapult launch is to transport the 'S to its intended location by a second air vehicle, for example as a payload itself in a rocket. However, it will be readily apparent that the configuration of a fixed wing UM.A does not easily lend itself to tranportation by a relatively slim vehicle such as a rocket.

One method of overcoming this problem is to employ a flexible wing of which the rogallo wing is one example.

According to one aspect of the present invention a method of deploying a tTh comprises transporting the wA by a second air vehicle, the UMA having a stowed flexible wing prior to release from the second air vehicle, releasing the UMA from the second air vehicle and deploying the W-IA flexible wing.

By employing a flexible wing the wing may be folded whilst the UMA is carried by the second air vehicle. Once the UMA has been released from the second air vehicle the wing may be deployed by the operation of an expanding strut and spar mechanism of suitable geometry. Deployment of the wing may be achieved automatically by any suitable system such as spring loaded lever mechanism, stored energy system,pneumatics, hydraulics etc.

Preferably the flexible wing is made from sheet or woven plastics material such as Kevlar (Trade Mark).

According to a feature of the present invention the UMA is transported to its point of release enclosed within a container which is jettisoned from the second air vehicle before deployment of the WiA from the container.

The purpose of the container is to protect the wing from possible damage due to air resistance effects during transportation by the relatively fast flying second air vehicle. The container may comprise the nose cone of a rocket or an airframe mounted releasable capsule on an aircraft.

Where the operational task of the UMA is to act as a decoy gliding flight may be considered with the W4A being expendable.

However1 where the operational task requires that the UMA be recovered to the ship then propulsion means may be required on the U-'.

Propulsion of the US may be achieved by a small internal combustion engine having either a conventional airscrew or being incorporated into a ducted-fan arrangement. If an internal combustion engine is employed it may be mounted either in a tractor or pusher configuration. The propulsion means may alternatively comprise an electric motor perhaps being powered by solar cells incorporated into the wing.

One of the operational criteria of a UMA used to support naval operations may be that it must be able to keep station with its launch ship or any other vessel in a group, which implies a requirement for low speed flight. A large area flexible wing of parasol configuration having a low centre of gravity by virtue of an underslung payload would provide the low wing loading and stability for low speed flight.

A flexible wing has the considerable advantage of endowing the TA with a relatively small radar signature while a small internal combustion engine similarly endows the UMA with a very low level of infra-red emission.

Attitude and directional control may be achieved by control surfaces attached either to a payload carrying fuselage structure or to a propulsion pod. Alternative methods of control such as vectoring the thrust of a propulsion pod or partial biased reefing of the wings may be used. Rapid and high manoeuvrability is not of great importance compared to stability and low speed flight capability, however, rapid control reaction to counteract air turbulence is necessary. By employing differential reefing of the wing high control forces may be achieved.

Relatively rapid height descent may be achieved by a temporary decrease in projected wing area by, for example, controlled reefing.

Recovery of a flexible winged UMA is facilitated in that the wing and power pod are of comparatively low cost and, therefore, may be considered as expendable. If the payload packaged in the fuselage unit is water tight and is either inherently buoyant or has inflatable buoyancy means then ditching of the UMA with subsequent trawl or similar recovery means becomes feasible.

Ditching of a conventional fixed wing UMA generally results in the air vehicle becoming unserviceable whilst in-flight recovery of a fast flying UMS presents a considerable hazard to the ship and its personnel. One of the advantages of a flexible wing is that forward velocity of the UMA may be reduced to a very low figure and the UMA recovered in a controlled stall landing.

In order that the present invention may be more fully understood one embodiment will now be described by way of example only with reference to the accompanying drawings. of which; Figure 1 shows a perspective schematic representation of a flexible winged UMA with the wing in the folded position.

Figure 2 shows the EMA of Figure 1 with the wing deployed.

Figure 3 shows a schematic representation of the UMA of Figure 1 contained within the nose cone of a rocket launch vehicle and Figure 4 which shows a schematic representation of a method of using a flexible winged UMA according to the present invention.

Common numbers in all of the figures refer to the same features. Referring now to Figures 1 and 2. A flexible winged UMA is shown generally at 10. The UMA has a wing 11 made from a strong flexible plastics material such as Kevlar (Trade Mark) which may be folded. Wing spars 12 are made from an aluminium alloy and are pivoted at the front end 13 to a central main rib 14. Attached to the main rib 14 by parallel arms 15 is a fuselage 16 carrying a payload 17 (not shown), propulsion means 18 and control surfaces 19. Movement in a downward and forwardly direction of the fuselage 16 relative to the main rib 14 causes the wing spars 12 to swing in an outwardly direction due to an operating linkage 20.Movement of the fuselage 16 relative to the main rib 14 is caused by resilient biasing means 21 (not shown) being brought into operation upon jettisoning of retention means 22 (not shown) employed to hold the UMA in the wing folded position.

At the maximum extent of travel of the spars 12 the arms 15 and operating linkage 20 assume a locked position.

Referring now to Figure 3. The UMA 10 is shown with the wing 11 folded and contained within the nose cone 30 of a rocket 31 which constitutes the second air vehicle used to transport the UMA 10 to its intended location. The nose cone 30 of the rocket 31 includes releasable half shells 32 allowing the UMA 10 to be launched at a desired height and position.

Referring now to Figure 4. In operation the rocket 31 containing the UMA 10 in its nose cone 30 is fired from a ship 40 (phase 'A'). The rocket/UMA 31/10 travels to its intended position whereupon the nose cone with the contained UMA is released from the rocket body. At the point of release a drogue chute 33 (not shown) is deployed from the nose cone 30 to retard velocity and stabilise flight attitude prior to release of the UMA from the nose cone. When the correct velocity and attitude have been achieved the UMA 10 is launched from the rocket nose cone 30 after jettisoning of the releasable half shells 32. The UMA 10 is launched with the wing 11 in the folded position (phase 'B'). A static line 34 (not shown) connected between the drogue chute 33 and the retention means 22 via one of the half shells 32 causes the retention means to free the wing folding mechanism.The wing 11 is then deployed and the propulsion means 18 started. The UMA 10 then enters phase 'C' of its mission which may include, for example, radar surveillance. Phase 'C' may often include the UMA 10 loitering for an extended period. Once the UMA has completed phase 'C' of its mission recovery to the launch ship (or any other) is then undertaken (phase 'D') in order to retrieve the payload. Such recovery may be by stall landing in the sea with subsequent trawl retrieval.

Although the launch vehicle described in the above example is a rocket other launch vehicles are also envisaged. For example, an alternative method would be that of launching the UMA from a capsule released from a VSTOL aircraft or helicopter, the capsule being carried on a wing or fuselage hard point. VSTOL aircraft are nowadays frequently flown from relatively small ships when assisting in naval operations. Indeed, it is envisaged that a single VSTOL aircraft could carry more than one UMA and deploy them in different locations to give enhanced defence to threats.

It will be clear to the person skilled in the art, however, that launching of the UMA may be made from virtually any airborne platform. For example, from a land based maritime reconnaisance aircraft acting in support of naval operations.

Deployment of the folded flexible wing is described above as being initiated from a static time between the wing retention means and a nose cone half shell. Wing deployment after release of the UMA from its container1 may however, be achieved by any suitable means operating, for example, on barometric pressure or with timing devices etc.

For the construction of the UMA other materials than those specified above may be used. For example, wing spars may be fabricated from fibre reinforced plastics rather than aluminium alloys especially where corrosion in storage may be a problem.

Other tasks for the UMA are also envisaged. These tasks may include the provision of ordnance in the payload such ordnance being terminally guided to a target either with the flexible wing in place or after jettisoning of the wing, provision being made on the payload fuselage for guidance means, for example, bystub wings.

Claims (7)

1. A method of deploying a UMA comprising transporting the UMA by a second air vehicle, the UMA having a stowed flexible wing prior to release from the second air vehicle, releasing the UMA from the second air vehicle and deploying the UMA flexible wing.

2. A method according to claim 1 and wherein the UMA is transported to its point of release enclosed within a container which is jettisoned from the second air vehicle before deployment of the UMA from the container.

3. A method according to either claim 1 or claim 2 and wherein the flexible wing is made from a plastics material.

4. A method according to claim 1 and wherein the second air vehicle is a rocket.

5. A method according to claim 1 and wherein the second air vehicle is a VSTOL aircraft.

6. A method according to claim 1 and wherein the second air vehicle is a land based aircraft.

7. An unmanned aircraft substantially as hereinbefore described with reference to the drawings.

7. A method according to claim 1 and wherein the second air vehicle is a helicopter.

8. A method according to any one of preceding claims 4, 5 or 7 and wherein the second air vehicle is launched from a sea-borne vessel.

9. A method according to any one preceding claim and wherein the UMA is recovered by a ship after its mission.

10. A method according to claim 1 and wherein a payload carried by the UMA is separately recoverable from the UMA.

Amendments to the claims have been filed as follows CLAIMS 1. An unmanned aircraft stowable in and launchable from a second air vehicle and comprising: a fuselage; a folding flexible wing extending between two or more spars pivotally attached to the front end of a central rib and adapted to abut the central rib in the folded position; linkage means connecting the spars to the fuselage; and two or more parallel arms connecting the central rib to the fuselage; such that on launch from the second air vehicle the fuselage is caused to move downwards and fowards relative to the central rib under the action of resilient biasing means, the action of the linkage means at the same time swingingthe spars outwardly from the central rib to deploy the wing until the linkage means assume a locked position on full wing deployment.

2. An unmanned aircraft as claimed in claim 1 further comprising releasable retaining means for retaining the wing in the folded position.

3. An unmanned aircraft as claimed in claim 2 wherein the retaining means is attached to a drogue parachute by a static line whereby after launching of the unmanned aircraft from the second air vehicle, the static line becomes taut and causes the retaining means to be released.

4. An unmanned aircraft as claimed in sny preceding claim wherein the folding flexible wing is made of a plastics material.

5. An unmanned aircraft as claim in any preceding claim and further comprising propulsion means.

6. A method of deploying an unmanned aircraft as claimed in any preceding claim whereby the unmanned aircraft is stowed in an openable container which is jettisoned from the second air vehicle prior to deployment of the flexible wing.