GB2600419A

GB2600419A - Recovery aircraft and method

Info

Publication number: GB2600419A
Application number: GB2017041.1A
Authority: GB
Inventors: Gerard West Michael
Original assignee: BAE Systems PLC
Current assignee: BAE Systems PLC
Priority date: 2020-10-27
Filing date: 2020-10-27
Publication date: 2022-05-04
Also published as: GB202017041D0

Abstract

A recovery aircraft 100 comprising a ventral trapeze for connecting to a re-entry aircraft R (e.g. spaceplane vehicle descending from space to Earth). The recovery aircraft has a ventral (lower) side 110 comprising a protruding linkage or trapeze 200 hanging down from the recovery aircraft ventral surface. The trapeze 200 may comprise a damping piston (40), main linkage (20, figure 6) and pivotally connected bars (24, 26). Distal bar (26) may comprise engagement structure (28), e.g. hook for fastening the re-entry vehicle. The recovery aircraft may comprise a tow line (50, figure 3) e.g. steel cable paid out and reeled in via a motorised spool. The tow line may comprise a drogue with latches for coupling to the re-entry vehicle. The tow may comprise an extensible telescopic boom comprising a rigid beam portion (60) extending from a pivoted joint (61). The tow may draw the re-entry vehicle onto the trapeze.

Description

RECOVERY AIRCRAFT AND METHOD

The present disclosure relates to a recovery aircraft and a method of recovering a re-entry vehicle.

Re-entry vehicles, which may alternatively be referred to as spaceplanes, are known. These vehicles are configured for descending from space to the surface of a planet, especially Earth.

Accordingly, re-entry vehicles are able not only to manoeuvre in space but also to glide, or perhaps fly to some extent, in a planet's atmosphere.

Certain re-entry vehicles are provided with wing or tail structures. Such structures tend to facilitate aerodynamic manoeuvres whilst gliding or flying in the planet's atmosphere.

Re-entry vehicles tend to have minimal propulsion systems for use in the planetary atmosphere. Re-entry vehicles may be provided with rocket motors for a short period of thrust.

Thus the flight or glide of the re-entry vehicle to the surface of the planet is constrained and accordingly the range of the re-entry vehicle is limited. Suitable landing locations, e.g. a landing strip, on the planet surface must be within the vehicle's range.

Significant forces can be exerted on the re-entry vehicle as it lands at the planet surface.

According to a first aspect of the present invention there is provided a recovery aircraft comprising: a ventral trapeze for forming a connection to a reentry aircraft.

There may also be provided: a tow having an end which may be extended beyond the aftward portion of the ventral trapeze and retracted back from this extended position; the tow comprising a fastener towards its extending end for attachment to a re-entry aircraft, such that the extended tow may fasten to a reentry aircraft and then, as the tow line retracts, guide said re-entry aircraft onto the ventral trapeze.

The tow may comprise a tow line for extending and retracting.

Further, the tow line may be paid out to reach a maximum distance behind the recovery aircraft of between 500m and 1500m.

Still further, the tow may comprise a boom, which may be extensible.

The boom may be pivotally attached to the recovery aircraft so as to be able to vary the angle between a centreline defined by the recovery aircraft and the boom.

The tow may be mounted at the ventral trapeze, and may be mounted at a forwards structure of the ventral trapeze.

Alternatively, the tow may be mounted at a ventral surface of the aircraft forwards of the ventral trapeze.

The ventral trapeze may comprise: a linkage extending ventrally and forwardly, the linkage comprising: at least one fastening for attaching to a reentry vehicle; and a suspension system for controlling oscillations of the trapeze with and without a re-entry vehicle attached.

According to a second aspect of the invention, there is provided a method of recovering a re-entry vehicle comprising: flying a recovery aircraft comprising a ventral trapeze; and guiding the re-entry vehicle onto ventral trapeze.

The method may comprise guiding the re-entry vehicle onto the ventral trapeze comprises using the propulsive capability of the re-entry vehicle.

Further, guiding the re-entry vehicle onto the ventral trapeze may comprise: deploying a tow; attaching the tow to the re-entry vehicle; and drawing in the tow to draw the re-entry vehicle onto ventral trapeze.

Still further, the tow may comprise a selectively extensible rigid portion and a selectively extensible line portion, and deploying the tow may comprise configuring the rigid portion and line portion into an extended state, anddrawing in the tow may comprises: firstly drawing in extensible line portion, and secondly drawing in the rigid portion.

Examples of the present disclosure will now be described with reference to the accompanying drawings, in which: Figure 1 shows a first embodiment of a recovery vehicle according to the present invention; Figure 2 shows second embodiment of a recovery vehicle according to the present invention; Figure 3 shows third embodiment of a recovery vehicle according to the present invention; Figure 4 shows fourth embodiment of a recovery vehicle according to the present invention; Figure 5 shows fifth embodiment of a recovery vehicle according to the present invention; Figure 6 shows a trapeze/linkage for use in the previous embodiments; and Figures 7, 8 and 9 show as flow diagrams, methods of recovering a reentry vehicle.

Referring to Figure 1, there is shown at 100 a recovery aircraft having the form of an airliner, specifically a jet airliner. There is also shown a re-entry vehicle R in proximity to the aircraft 100.

The recovery aircraft 100 defines a forward portion 104, an aftward portion 106, a dorsal (or upper) side 108 and a ventral (or lower) side 110. These portions and sides are generally defined relative to a centre of mass 111 of the aircraft. The substantially tubular form of the aircraft also defines a central axis.

The recovery aircraft 100 comprises a tail structure 112 at its aft.

The recovery aircraft 100 further comprises a protruding linkage or trapeze 200 extending from the ventral side 110 of the aircraft 100 and proximate to the centre of gravity 111 of the aircraft 100.

Referring additionally to Figure 6, the trapeze 200 generally provides a 25 dynamically tuned linkage (e.g. a linkage with stiffness and damping characteristics predetermined with regard to expected operational loadings) hanging down from a ventral surface 110 of the recovery vehicle 100.

More specifically the trapeze 200 comprises a main linkage 20 extending pivotally from the ventral surface 110. The main linkage has two pivotally 30 connected bars 24, 26, arranged in series and which hang forward and downward from the recovery vehicle 100.

The proximate bar 24 of the linkage 20 extends from the ventral side of the vehicle 100 and is pivotably connected thereto. The proximate bar 24 subtends a first angle al between itself and the central axis of the aircraft 100.

The first angle al is less than 90°, which can tend to provide scope for minor forward rotations (i.e. which tend to reduce the first angle). Such rotations can permit the mechanism to deform in the event of an impact from e.g. a vehicle travelling aft to forward of the ventral side of the aircraft 100.

The distal bar 26 extends from a pivotable connection with the proximate bar 24, and second angle a2 is subtended between the proximate 24 and distal 26 bars.

The second angle a2 is between 90 and 180°, which tends to present an inclined surface to an oncoming re-entry vehicle that generally corresponds with the profile of the nose of the vehicle R. The distal bar 26 comprises at least one engagement structure 28 (e.g. a hook) where the re-entry vehicle R may fasten. The engagement structure 28 corresponds with a structure (e.g. a lug) on the re-entry vehicle R to effect the connection. The engagement structure 28 may be configured to connect to the re-entry vehicle R at or substantially near to the re-entry vehicle R's centre of gravity, and a further engagement structure 28 may grip at or close to the nose of the re-entry vehicle R. So as to extend between the nose and centre of gravity of the re-entry vehicle R, the distal bar 26 may be between 2m and 7m long.

A damping piston 40 connects between a region towards the distal end of the distal bar 26, and a portion of the recovery vehicle ventral surface that is 25 forward of the trapeze.

The trapeze also comprises a linear actuator 30. The actuator 30 extends pivotally from the ventral surface 110 at a point aftward of the proximate bar 24 and connects pivotally to the linkage 20 at a point between the respective connections of the proximate bar 24 and the damping piston 40.

The actuator 30 is shown in a generally extended condition, but is operable to contract to a shorter length. Extension and retracting of the actuator 30 varies the attitude of distal bar 26.

A first and second predetermined series of expansions and contractions 5 of the actuators and pistons of mechanism 200 can effect respectively the stowing or deployment of the trapeze 200.

For example, starting from the deployed condition shown in Figure 6, a contraction of piston 40 combined with a rotation of proximate bar 24 to reduce angle al (effected by a motor (not shown) or further linear actuator (not shown)) would tend to effect transition to a stowed configuration. Conversely, if starting from a stowed condition, an extension of the piston 40 combined with a rotation of proximate bar 24 can effect the deployment of the trapeze 200.

In operation, the recovery aircraft 100 flies to an altitude of approximately 12,000m (40,000 feet), over or on an anticipated glide/flight path of the spaceplane IR, then aligns with the azimuth direction of the path, and then commences a steep descent of approximately 15 to 20 degrees at a steady indicated airspeed. Then as a re-entry vehicle descends from space into the atmosphere along its path, and reaches the altitude of the recovery aircraft 100, the re-entry vehicle R glides onto the trapeze 200, couples at the engagement structures 28, and thereby couples to the recovery vehicle 100. Once coupled, the recovery aircraft 100 may pull out of the descent to level flight and then transit to any suitable landing site in range.

Referring to Figure 2 there is shown a further recovery aircraft 120 where the trapeze 200 further comprises a tow in the form of a tow line 50. The tow line 50 is in the form of a cable formed, for example, from a steel or a polymer material (e.g. a manufactured fibre spun from a liquid-crystal polymer such as Vectran TM).

The tow line 50 extends from the trapeze 200 at a substantially front-most and ventral-most portion of the trapeze 200. The tow line 50 is stored on a motorised spool (not shown) and as such can be paid out or reeled in. In particular, the tow line 50 can be paid out from the trapeze 200 to a length of 500m to 1500m, or 750m to 1250m, or 1km behind the aircraft 120.

At the distal end of a tow line 50 there is provided a fastener (e.g. a hook or a drogue with multiple latches) for coupling to a guide port (e.g. a lug) at the re-entry vehicle R. In operation the recovery aircraft 120 flies to an altitude of approximately 12,000m (40,000 feet), over or on an anticipated glide/flight path of the re-entry vehicle R, then aligns with the azimuth direction of the anticipated path, and then commences a steep descent of approximately 15 to 20 degrees at a steady indicated airspeed. The tow line 50 is extended (for example 1000m) behind the recovery aircraft 120, such that as a re-entry vehicle R descends from space into the atmosphere, and reaches the general altitude of the recovery aircraft 120, the re-entry vehicle R may glide to a point 1000m behind the aircraft 120, connect to the tow line 50, whereupon the recovery aircraft 120 can pull out of the dive and the motorised spool can wind the tow line in, thereby bringing the re-entry vehicle R onto the trapeze 200 (and the engagement surfaces 28 thereon) and thereby couple the re-entry vehicle R to the recovery vehicle 120. The aircraft 120 may then pull out of the dive and then transit to any suitable landing site in range.

Referring to Figure 3 there is shown a recovery aircraft 130 which comprises a trapeze 200 as shown in Figure 1 and further comprises a tow in the form of a boom 300.

The boom 300 extends from a pivoted joint at the ventral side 110 of the aircraft 130 which is forward of the trapeze 200.

The boom 300 comprises a rigid beam portion 60 which extends from a pivoted joint 61 on the ventral side 110 of the aircraft 100, and a tow line 50 which extends from the rigid portion 60. From the pivoted joint 61, the boom 300 subtends an angle a3 with the central axis of the aircraft 130 which approximates to 180° when the boom is stowed (i.e. it lies flat and backwards), and approximates to between 140-160° when the boom is in a deployed condition.

The rigid beam portion 60 is formed from concentric tubes 64 and 65 which may slide in and out of each other (e.g. a telescopic mechanism) and thereby extend or contract the rigid beam portion 60. The concentric tubes 64 and 65 are formed, for example, from aluminium. Further, the tow line 50 is provided at a motorised spool (not shown) so as to allow the tow line 50 to be paid out or reeled in. As such the boom 300 may extend and contract. (In alternative embodiments contemplated by the present application, only one of the rigid portion 60 or the tow line 50 may be capable of extending and retracting).

The tow line 50 can be paid out from the rigid beam portion 60 to a length of 500m to 1500m, or 750m to 1250m, or 1km behind the aircraft 120.

In operation the recovery aircraft 130 flies to an altitude of approximately 12,000m (40,000 feet), over or on an anticipated glide/flight path of the re-entry vehicle R, then aligns with the azimuth direction of the path, and then commences a steep descent of approximately 15 to 20 degrees at a steady indicated airspeed. The boom 300 is deployed, by pivoting at joint 61 to reduce angle a3, then extending the rigid beam portion and then paying out the tow line 50. Such deployment provides a distal end of the boom 300, which is the distal end of the two line 50 at approximately 1000m (for example) behind the aircraft 130. Thus as a re-entry vehicle R descends from space into the atmosphere, and reaches the general altitude of the recovery aircraft 130, the re-entry vehicle R may glide to a point 1000m behind the aircraft 120, connect to the tow line 50, whereupon the recovery aircraft can start to pull out of the dive and the motorised spool can wind the tow line in, and/or the rigid beam portion 60 may contract or pivot, thereby bringing the re-entry vehicle R onto the trapeze 200 (and the engagement surfaces 28 thereon) and thereby couple to the recovery vehicle 130. The aircraft 130 may then finish pulling out of the dive if not already done so and then transit to any suitable landing site in range.

Referring to Figure 4, a recovery aircraft 140 comprising a ventral 30 trapeze 200 is shown further comprising a tow in the form of boom 340 which comprises a rigid beam portion 60 extending from a pivot joint 61 at the ventral surface 110 of the aircraft 140.

The boom 340 is pivotally connected to the aircraft 140 by the joint 61 at a point forward of the trapeze 200 such that the boom 300 may lie flat and backward against the ventral surface of the aircraft 140 (e.g. angle a3 is 180 degrees), or may swing into a deployed condition where it hangs backwards and downwards (e.g. angle a3 is approximately 140-160 degrees).

Further, the rigid beam portion 60 comprises at least an outer tube 64 and an inner tube 65 which can slide within each other to extend or contract the overall length of the boom 340.

In operation the recovery aircraft 140 flies to an altitude of approximately 12,000m (40,000 feet), over or on an anticipated glide/flight path of the spaceplane R, and then commences a steep glide of approximately 15 to 20 degrees at a steady indicated airspeed. The boom 340 is deployed, by swinging out from the pivot joint 61 and extending the rigid beam portion 60, such that as a re-entry vehicle R descends from space into the atmosphere, and reaches the general altitude of the recovery aircraft 130, the re-entry vehicle R may glide to the distal end 62 of the rigid beam portion 60 and]connect thereto, whereupon the recovery aircraft 140 can start to pull out of the dive and the rigid beam portion 60 may contract and swing back in towards the ventral surface 110, thereby bringing the re-entry vehicle R onto the trapeze 200 (and the engagement surfaces 28 thereon) and thereby coupling it to the recovery vehicle 140. The aircraft 140 may then finish pulling out of the dive if not already done, and then transit to any suitable landing site in range.

Referring to Figure 5, the re-entry vehicle R is provided with a propulsive system (such as rocket motors) for limited thrust-powered flight. As such, this propulsive system can be used to assist with the coupling together of the recovery aircraft and the re-entry vehicle. In Figure 5, the propulsive capability T is shown as an addition to the Figure 2 example; however this provision is also applicable to the embodiments shown in Figures 1, 3 and 4 as well as others contemplated herein.

The recovery aircraft comprises a transmitter/receiver unit (not shown) for sending control messages to the re-entry vehicle, and accordingly re-entry vehicles R are provided with corresponding receiver/transmitter units (not shown). Such control messages may be machine readable and hence for instructing the re-entry vehicle flight control computer directly, or may be human readable and hence for issuing a command to a pilot on the re-entry vehicle. Thus a communications link (shown as a dot dash line) is provided between the recovery aircraft 120 and the re-entry vehicle R. Referring to Figure 7, a method of recovering a re-entry vehicle R is shown whereby at step S2, a recovery aircraft comprising a ventral trapeze 200 is flown, and at step S4, a re-entry vehicle R is guided onto the ventral trapeze 200 of the recovery vehicle. Further, an optional step S3, which may be performed at substantially the same time with step S4, comprises using the propulsive capability T of the re-entry vehicle R. Referring to Figure 8, an expanded set of sub-steps for step S4 is shown in respect of the embodiments comprising a tow. As such at step S6 the recovery aircraft deploys a tow, and at step S8 the tow is attached to the reentry vehicle R, and at step S10 the tow is drawn in to draw the re-entry vehicle R onto the ventral trapeze 200.

Referring to Figure 9, an expanded set of sub-steps for step S2 are shown. At step S21 the recovery aircraft ascends, for example to a point at or above an anticipated flight path of a re-entry vehicle. This may be at or around 12,000 m altitude (40,000 ft). At step S22 the flight direction of the recovery aircraft is aligned with the anticipated azimuth flight direction of the re-entry vehicle. At step S23 the recovery aircraft starts to descend. Such descent may involve matching the attitude glide path angle of the re-entry vehicle R if the recovery aircraft has started on a point on the anticipated glide path. Such a descent may be at 15 to 20 degrees.

Accordingly, there is facilitated the controlled recovery of a re-entry vehicle which recovery is not limited by the availability of runways or landing sites within the range of the re-entry vehicle. Further, by tending to remove the need for the -10 -re-entry vehicle to land itself, which can be a physically demanding process, it can help to reduce damage to the re-entry vehicle (or offer different strength and weight characteristics) and thereby potentially allow reuse of the re-entry vehicle.

Further, there tends to be removed the need for the re-entry vehicle to have its own undercarriage for landing. Re-entry vehicles configured for the present system can therefore be absent their own undercarriage and so can be of reduced size, complexity and weight.

The provision of the trapeze enables a stable and/or readily tuned mechanical structure for connecting to the re-entry vehicle. It can also be configured for stowage so that the aerodynamic impact when not coupling to the re-entry vehicle can be reduced.

The provision of the extendable and retractable tow allows the initial contact between the recovery aircraft and the re-entry vehicle to take place with a safe distance between the recovery aircraft and re-entry vehicle.

In particular, the tow line -in providing a light but strong cable which can be stored in a compact form when reeled in, but then extend to 500-1500m when deployed -can facilitate a particularly safe distance for the initial contact.

Where a rigid beam is provided as part of the tow, this can allow the re-entry vehicle to approach the recovery aircraft at an offset altitude and thereby help to reduce the effect of the recovery aircraft airflow on the re-entry vehicle flight.

As discussed above, the recovery aircraft is based on a jet airliner. However, various relatively large aircraft are contemplated which should be suitable for use as the recovery vehicle. In general the aircraft may be one having a length in the range of 45m-75m with a wingspan in the range of 4080m and capable of generating total thrust of 750kN-1500kN. As such a number of commercial airliners (for example the Boeing 747, the Boeing 777, or the Airbus A380) and military transport vehicles (for example the A400M, the C17 or the C5) are expected to be suitable.

Various re-entry vehicles and spaceplanes are known and have been contemplated. Particularly contemplated here as suitable are re-entry vehicles having a length in the range of 5-10m and a wingspan/width in the range 2-8m. Some examples of these such as the ESA Hermes may have relatively high lift-to-drag ratios, whereas others such as the ESA Intermediate Experimental Vehicle 'IXV may have relatively low lift-to-drag ratios.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

-12 -CLAIMS 1.A recovery aircraft comprising: a ventral trapeze for forming a connection to a re-entry aircraft. 2.
A recovery aircraft according to claim 1 further comprising: a tow having an end which may be extended beyond the aftward portion of the ventral trapeze and retracted back from this extended position; the tow comprising a fastener towards its extending end for attachment to a re-entry aircraft, such that the extended tow may fasten to a re-entry aircraft and then, as the tow line retracts, guide said re-entry aircraft onto the ventral trapeze. 3.
A recovery aircraft according to claim 2 wherein the tow comprises a tow line for extending and retracting. 4
A recovery aircraft according to claim 3 wherein the tow line may be paid out to reach a maximum distance behind the recovery aircraft of between 500m and 1500m. 5.
A recovery aircraft according to any one of claims 2 to 4 wherein the tow comprises a boom.
A recovery aircraft according to claim 5 wherein the boom is extensible.
-13 -A recovery aircraft according to claim 5 or claim 6 wherein the boom is pivotally attached to the recovery aircraft so as to be able to vary the angle between a centreline defined by the recovery aircraft and the boom. 8.
A recovery aircraft according to any of claims 2 to 7 wherein the tow is mounted at the ventral trapeze. 9.
A recovery aircraft according to claim 8 wherein the tow is mounted at a forwards structure of the ventral trapeze. 10.
A recovery aircraft according to any one of claims 2 to 7 wherein the tow is mounted at a ventral surface of the aircraft forwards of the ventral trapeze.
11. A recovery aircraft according to any of the previous claims wherein the ventral trapeze comprises: a linkage extending ventrally and forwardly, the linkage comprising at least one fastening for attaching to a re-entry vehicle; a suspension system for controlling oscillations of the trapeze with and without a re-entry vehicle attached.
12. A method of recovering a re-entry vehicle comprising: -flying a recovery aircraft comprising a ventral trapeze; and - guiding the re-entry vehicle onto ventral trapeze.
13. A method according to claim 12 wherein - guiding the re-entry vehicle onto the ventral trapeze comprises using the propulsive capability of the re-entry vehicle.
-14 - 14. A method of recovering a re-entry vehicle according to claim 12 or claim 13 wherein - guiding the re-entry vehicle onto the ventral trapeze comprises: o deploying a tow; o attaching the tow to the re-entry vehicle; and o drawing in the tow to draw the re-entry vehicle onto ventral trapeze.
15. A method according to claim 14 wherein -the tow comprises a selectively extensible rigid portion and a selectively extensible line portion, and - deploying the tow comprises configuring the rigid portion and line portion into an extended state, and - drawing in the tow comprises: o firstly drawing in extensible line portion, and o secondly drawing in the rigid portion. 20