GB2600421A

GB2600421A - Recovery aircraft and method

Info

Publication number: GB2600421A
Application number: GB2017043.7A
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
Anticipated expiration: 2040-10-27
Also published as: GB202017043D0; GB2600421B

Abstract

A recovery aircraft 100 comprising a tow for initial attachment to a re-entry vehicle Rd, and a docking station at which a re-entry vehicle may establish a second attachment. The tow guides the re-entry vehicle to the docking station. The re-entry aircraft may be a spaceplane vehicle descending from space to Earth. The docking station and tow may be provided on recovery aircraft upper or lower surface. The tow may comprise an extensible telescopic boom comprising a rigid beam portion 60 extending from a pivoted joint 61. A trailing tow line 50, e.g. steel cable paid out and reeled in via a motorised spool, may extend from the rigid beam portion 60. The docking station may comprise a cradle structure protruding backwards from the aft of the recovery aircraft, or a damped linkage, or a pylon 400. The pylon may have a rigid rail system comprising a gripping mechanism.

Description

RECOVERY AIRCRAFT AND METHOD

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

Various re-entry vehicles, which may alternatively be referred to as spaceplanes, are known. These vehicles are configured for travelling through a planet's atmosphere into space, and 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 in the planet's atmosphere.

Re-entry vehicles tend to have minimal propulsion systems for use in the 15 planetary atmosphere. Re-entry vehicles may be provided with rocket motors for a short period of thrust.

The flight or glide of the re-entry vehicle to the surface of the planet has therefore tended to require the availability of a suitable landing spot on the planet surface, which is in range of the vehicle's descent.

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

According to a first aspect of the present invention there is provided a recovery aircraft comprising: a tow for establishing an initial attachment to a reentry vehicle; and a docking station at which a re-entry vehicle may establish a second attachment, wherein the tow is operable to guide the re-entry vehicle to the docking station.

The docking station may be at a surface of the recovery aircraft that is generally at the aerodynamic centre of the recovery aircraft.

Further, the docking station may be on a dorsal surface of the recovery aircraft.

Alternatively, the docking station may be on a ventral surface of the recovery aircraft.

The tow may be mounted forward of the aerodynamic centre of the recovery aircraft and on the same ventral or dorsal side of the recovery aircraft as the docking station.

The tow may comprise a boom comprising a mount end, at which the boom fastens to the recovery aircraft, and a distal end for attaching to a re-entry vehicle.

The boom may be pivotally mounted at the mount end so as to vary the pitch angle between the boom and the centreline of the recovery aircraft.

The boom may be extensible and retractable.

The boom may comprise: a rigid portion; and a line portion, the rigid portion extending from the mount end to the line portion, the line portion extending from the rigid portion and terminating in the distal end.

It can be provided that the line of the line portion may be selectively paid out and drawn in. When paid out, the tow may extend between 500m and 1500m behind the recovery aircraft, and may extend between 750m and 1250m behind the recovery aircraft.

According to a second aspect of the invention there is provided a method for coupling a re-entry vehicle to a recovery vehicle whilst both are in flight, the method comprising: providing a docking station at the recovery vehicle for selectively fastening to the re-entry vehicle; providing a structure for engaging the docking station at the re-entry vehicle; guiding the re-entry vehicle to the docking station, such that the docking station and the structure for engaging the docking structure are sufficiently proximate; and activating the docking station to attach the re-entry vehicle at the recovery vehicle.

The method may further comprise deploying a boom from the recovery vehicle; attaching a distal end of the boom to the re-entry vehicle, and wherein guiding the re-entry vehicle to the docking station comprises retracting the boom. It may be provided that the boom comprises: a rigid portion pivotably attached to the recovery vehicle and being selectively extensible and retractable along a longitudinal axis defined by the rigid portion and wherein: deploying the boom comprises: pivoting the boom to incline it away from a surface of the recovery aircraft; and extending the rigid portion of boom.

Further, it may be provided that the boom comprises: a line portion extending from the rigid portion and being selectively extensible and retractable, and wherein deploying the boom comprises paying out the line portion of boom.

Attaching the boom to the re-entry vehicle may comprise attaching the line portion to the re-entry vehicle.

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; and Figures 3, 4, 5 and 6 show as flow diagrams, methods of recovering a reentry vehicle.

Referring to Figure 1, there is shown at 100 a first recovery aircraft having the form of an airliner, specifically a jet airliner.

There is also shown a re-entry vehicle Rd in proximity to the aircraft 100, below and slightly behind.

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 tow in the form of a boom 300, and a docking station. The docking station has the form of a pylon 400.

The pylon 400 is in the form of a rigid rail system which protrudes along a portion of the recovery aircraft 100 surface. The rail system comprises a gripping mechanism (not shown) for engaging with corresponding structures on a re-entry vehicle.

The pylon 400 is mounted on a ventral surface 110 of the aircraft 100 and in proximity to the centre of gravity 111. As shown in the Figure 1 embodiment, the pylon 400 is directly below the centre of gravity 111. The pylon 400 is configured to grip a corresponding structure e.g. a rail Sd on the dorsal side of the re-entry vehicle Rd.

The boom 300 extends from a pivoted joint 61 at the ventral side 110 of the aircraft 100. The pivoted joint 61 is forward of the pylon 400.

The boom 300 comprises a rigid beam portion 60, and a tow line 50. The rigid beam portion 60 extends from the pivoted joint 61 on the ventral side 110 to a distal end 62. The tow line 50 extends from the distal end 62 of the rigid portion 60.

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 VectranTm).

From the pivoted joint 61, the rigid portion 60 subtends an angle a3 with the ventral surface 110 of the aircraft 130 which approximates to 180° when the boom is in a stowed condition (i.e. it lies flat and backwards), and approximates 15 to between 140-160° when the boom is in a deployed condition (as shown).

The rigid beam portion 60 is formed from concentric tubes, an outer tube 64 and an inner tube 65, which may slide in and out of each other (i.e. a telescopic mechanism) and thereby extend or contract the rigid beam portion 60. The concentric tubes are formed, for example, from aluminium.

The tow line 50 is provided at a motorised spool so as to allow the tow line to be paid out or reeled in.

As such the boom 300 may extend and contract through the movement of the rigid beam and the tow line. (In alternative embodiments contemplated by the present application, only one of the rigid portion or the tow line may be capable of extending and retracting).

The tow line 50 can be paid out from the rigid beam portion 60 such that the boom 300 extends to a length of 500m to 1500m, or 750m to 1250m, or 1km behind the aircraft 100.

In operation the recovery aircraft 100 flies to an altitude of approximately 12, 000 m (40,000 feet), over or on an anticipated glide/flight path of the re-entry vehicle Rd, 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.

Prior to the recovery aircraft 100 entering the descent, or during the descent, the boom 300 is swung out from a stowed angle (by pivoting at joint 61 to incline downward from the ventral surface 110) and extended (by extending the rigid portion 60 and paying out the tow line 50) such that the distal end of the tow line is 1000m (for example) behind the aircraft, Thus, as a re-entry vehicle Rd descends from space into the atmosphere, and reaches the altitude of the recovery aircraft 100, the re-entry vehicle Rd may glide to a point 1000m behind the aircraft 100, and connect to the trailing tow line 50, whereupon the motorised spool can wind the tow line 50 in, and the rigid beam portion 60 may contract, thereby bringing the re-entry vehicle R towards the ventral pylon 400. Further, the rigid beam portion 60 may pivot about joint 61 so as to bring the rigid beam portion 60 towards the ventral surface 110 and thereby bring the re-entry vehicle R closer to the pylon 400.

Through such combination of said retractions and pivots, the rail Sd of the re-entry vehicle Rd can be brought within range of a gripping mechanism (not shown) of the pylon 400, such that the gripping mechanism can be activated to couple to the re-entry vehicle Rd to the recovery vehicle 100.

Hence the re-entry vehicle Rd is recovered on the ventral side of the aircraft 100. At such point, the aircraft 100 can pull out of the descent and then transit to any suitable landing site.

Referring to Figure 2, there is shown at 102 a second recovery aircraft having the form of an airliner, specifically a jet airliner.

There is also shown a re-entry vehicle Rv in proximity to the aircraft 100, above and slightly behind.

The second recovery aircraft 200 has features in common with the first recovery aircraft 100 but differs in providing both a pylon 400 and a boom 300 mounted on the dorsal (or upper) surface 108 of the aircraft 102. The pylon 400 is proximate to the centre of gravity of the aircraft (for instance it is directly above it). The boom 300 is forward of the pylon 400.

As such the second recovery aircraft 102 is adapted for use with a re-entry vehicle Rv having a ventral structure (e.g. rail Sv) for coupling with the pylon 400 and operates to couple the re-entry vehicle Rv at the aircraft 102 dorsal surface 108.

The second recovery aircraft 102 operates to couple with the re-entry vehicle Sv in a substantially equivalent manner to aircraft 100 and vehicle Rd but with adaptations made for the dorsal rather than ventral approach.

With the tail structure 112 protruding dorsally, deployment of the boom 300 and retraction of the boom are done with regard to the relative positions of the end of the boom and the tail 112. This can tend to reduce to risk of the boom 300 or the re-entry vehicle Rv striking the tail 112.

As such, for aircraft 102, when the boom is deployed from a stowed condition, the first step is to swing the boom 300 away from the dorsal surface to a safe inclination (e.g. so that a3 is 140 to 160 degrees). The second step is to extend the rigid beam portion 60. The third step, which occurs when steps 1 and 2 have been completed, is to gradually pay out the tow line 50.

Further, once the boom 300 is fully deployed to approximately 1000m and the re-entry vehicle Rv is attached to the distal end thereof, the drawing-in of the boom 300 is substantially similar but further provisions for tail strike mitigation are as follows: the tow line 50 is reeled in first and once that has been fully reeled in then the rigid beam portion can retract and pivot into the dorsal surface.

It is contemplated that either of the re-entry vehicles Rv or Rd can be provided with a propulsion system to assist with its manoeuvres towards the boom or docking station. Such a propulsion system may be a rocket motor.

It is contemplated that in embodiments of the invention provisions can be made for a communications link between the recovery aircraft and the re-entry vehicle. This may further assist with coordinating the coupling of the aircraft and the vehicle.

A generalised method for recovering a re-entry vehicle is as follows Referring to Figure 3, a method of recovering a re-entry vehicle is shown whereby at step 52, a recovery aircraft is flown comprising a docking station (e.g. a pylon 400) and a boom 300, and at step 54, a re-entry vehicle is guided onto the docking station. Further, an optional step S3, which may be performed in tandem with S4 comprises using the propulsive capability of the re-entry vehicle.

Referring to Figure 4, sub-steps for achieving step 52 are shown.

At step 521 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 commences a descent. 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.

Referring to Figure 5, an expanded set of sub-steps for step 54 is shown. As such at step S6 the recovery aircraft deploys the boom 300, and at step S8 the boom 300 is attached to the re-entry vehicle R, and at step 510 the boom 300 is draw in to draw the re-entry vehicle R onto the docking station.

Referring to Figure 6, an expanded set of sub-steps for sub-step S6 is shown. As such, at step S12, the boom (preconfigured in a stowed condition and lying flat against the surface of the recovery aircraft and in a retracted length condition) pivots about a joint to incline the boom downwards away from the ventral surface 110. Then, at step S14 the rigid beam portion 60 extends and at step S16 the line 50 can be paid out from the boom.

Step S12 tends to precede steps S14 and S16. Steps S14 and S16 can occur in parallel, provided that the length of the partially paid-out tow-line 50 does not exceed the distance between the distal end 62 of the rigid portion 60 and the ventral surface 110 of the aircraft (this tends to ensure the tow line 50 is entrained in the ambient airflow before it reaches a length where it could strike the aircraft).

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 glide range of the re-entry vehicle. Further, by tending to remove the need for the 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 10 system can therefore be absent their own undercarriage and so can be of reduced size, complexity and weight.

The provision of the boom enables a stable 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 40-80m 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.

Alternative docking stations to the pylon would include a trapeze or a cradle.

A trapeze may be a damped linkage extending from a ventral surface of a recovery aircraft. It presents a surface or surfaces for engaging with the re-entry vehicle.

A cradle may be a structure protruding backwards from the aft of the aircraft. It presents a surface or surfaces for engaging with the re-entry vehicle.

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

-10 -CLAIMS 1.
A recovery aircraft comprising: a tow for establishing an initial attachment to a re-entry vehicle; and a docking station at which a re-entry vehicle may establish a second attachment, wherein the tow is operable to guide the re-entry vehicle to the docking station. 2.
A recovery aircraft according to claim 1 wherein the docking station is at a surface of the recovery aircraft that is generally at the aerodynamic centre of the recovery aircraft. 3.
A recovery aircraft according to any of the previous claims wherein the docking station is on a dorsal surface of the recovery aircraft. 4
A recovery aircraft according to claim 1 or claim 2 wherein the docking station is on a ventral surface of the recovery aircraft. 5.
A recovery aircraft according to any one of the preceding claims wherein the tow is mounted forward of the aerodynamic centre of the recovery aircraft and on the same ventral or dorsal side of the recovery aircraft as the docking station. 6.
A recovery aircraft according to any one of the preceding claims wherein the tow comprises a boom comprising a mount end, at which the boom fastens to the recovery aircraft, and a distal end for attaching to a re-entry vehicle. 7.
A recovery aircraft according to claim 6 wherein the boom is pivotally mounted at the mount end so as to vary the pitch angle between the boom and the centreline of the recovery aircraft. to 8.
A recovery aircraft according to claim 6 or 7 wherein the boom is extensible and retractable A recovery aircraft according to any one of claims 6, 7 or 8 wherein the boom comprises: a rigid portion; and a line portion, the rigid portion extending from the mount end to the line portion, the line portion extending from the rigid portion and terminating in the distal end. 10.
A recovery aircraft according to claim 9 wherein the line of the line portion may be selectively paid out and drawn in and optionally, when paid out, the tow 25 extends between 500m and 1500m behind the recovery aircraft, and may extend between 750m and 1250m behind the recovery aircraft.
11. A method for coupling a re-entry vehicle to a recovery vehicle whilst both are in flight, the method comprising: -providing a docking station at the recovery vehicle for selectively fastening to the re-entry vehicle; -12-
-providing a structure for engaging the docking station at the re-entry vehicle; - guiding the re-entry vehicle to the docking station, such that the docking station and the structure for engaging the docking structure are sufficiently proximate; and - activating the docking station to attach the re-entry vehicle at the recovery vehicle. 12. A method according to claim 11 further comprising: -deploying a boom from the recovery vehicle; - attaching a distal end of the boom to the re-entry vehicle, and wherein guiding the re-entry vehicle to the docking station comprises retracting the boom.
13. A method according to claim 12 wherein the boom comprises: a rigid portion pivotably attached to the recovery vehicle and being selectively extensible and retractable along a longitudinal axis defined by the rigid portion and wherein: -deploying the boom comprises: o pivoting the boom to incline it away from a surface of the recovery aircraft; and o extending the rigid portion of boom.
14. A method according to claim 13 wherein the boom comprises: a line portion extending from the rigid portion and being selectively extensible and retractable, and wherein - deploying the boom comprises paying out the line portion of boom. 30
15. A method according to claim 14 wherein - attaching the boom to the re-entry vehicle comprises attaching the line portion to the re-entry vehicle.