GB2600422A

GB2600422A - Recovery aircraft and method

Info

Publication number: GB2600422A
Application number: GB2017044.5A
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: GB202017044D0; GB2600422B

Abstract

A recovery aircraft 100 (102, figure 3) comprising a cradle 500, (502) extending back from the aft of the recovery aircraft onto which a re-entry vehicle R may dock. The cradle may extend aft from a region at the base of the tailplane (empennage or tail structure). The cradle may comprise an upper surface for fastening to an underside of the re-entry vehicle (e.g. spaceplane vehicle descending from space to Earth). The recovery aircraft may comprise a tow line 50 extending aftwards, e.g. a steel cable paid out and reeled in via a motorised spool. The tow line may comprise an attachment for fastening to the re-entry vehicle. The cradle 500 may comprise a pair of parallel beams defining a space between them that the re-entry vehicle may occupy and couple to. The cradle (502) may comprise a dynamically tuned structure (520, 530), e.g. spring and damping elements.

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 cradle extending back from the aft of the recovery aircraft onto which a re-entry vehicle may dock.

The recovery aircraft may comprise a tailplane with one vertical tail fin and two horizontal tail fins formed in a T-tail configuration, a cruciform configuration or a fuselage mounted configuration, and wherein the cradle extends aftwards from a region at the base of the tailplane.

The cradle may comprise an upper surface for fastening to an underside of the nose of a re-entry vehicle.

The cradle may extend aftwards from the fuselage of the recovery aircraft by length predetermined with reference to a re-entry vehicle so as to be equal to -2 -or greater than the distance between the nose and to the centre of gravity of said re-entry vehicle.

The cradle may extend a distance between 5 and 10m aftwards of the recovery aircraft.

The recovery aircraft may further comprise: a tow line, extending aftwards and which may selectively extend or retract.

Further, the tow line may comprise: an attachment for fastening to a re-entry vehicle.

The tow line may extend backward of the recovery aircraft a maximum 10 distance in the range of 500m to 1500m, or more particularly in the range of 750m to 1250m.

The cradle may comprise: a mount portion fastened to the recovery vehicle tail and extending therefrom; a trap portion for selectively attaching to a re-entry vehicle; and a shock absorbent mounting interconnecting the mount portion and the trap portion.

According to a second aspect of the invention there is provided a method of coupling a re-entry vehicle to a recovery vehicle while both are in flight comprising: providing a cradle at the aft of the recovery vehicle for selective engagement of the re-entry vehicle; manoeuvring the re-entry vehicle onto the cradle; and engaging the cradle to effect the coupling.

The cradle may be provided with a variable length tow, and manoeuvring the re-entry vehicle onto the cradle may comprise: extending the tow; coupling the tow to the re-entry vehicle; and drawing in the tow towards the cradle.

Further, extending the tow may comprise extending a tow line from the aircraft, and further, extending the tow may comprise extending the tow line to a distance of between 500m and 1500m behind the recovery vehicle.

Manoeuvring the re-entry vehicle onto the cradle may comprise utilising a propulsion system of the re-entry vehicle.

Examples of the present disclosure will now be described with reference to 30 the accompanying drawings, in which: Figures la and lb show a first embodiment of a recovery vehicle according to the present invention; -3 -Figures 2a and 2b show a second embodiment of a recovery vehicle according to the present invention; Figure 3 shows a portion of a third embodiment of a recovery vehicle according to the present invention; and Figure 4 and 5 show diagrammatically, methods of recovering a re-entry 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, and approaching under its own thrust T. The aircraft 100 defines a central axis and a centre of gravity 111. The central axis tends to pass through the centre of gravity 111. The substantially tubular form of the aircraft also defines a central axis.

The recovery aircraft 100 comprises an empennage or tailplane or tail structure, shown generally at 112, at its aft.

The tail structure 112 comprises a vertical stabiliser or tail fin 112a extending dorsally from the fuselage at the aft of the aircraft 100. Further, the tail structure 112 comprises a pair of horizontal stabilisers 112b extending from either side of the fuselage at the aft of the aircraft 100.

The recovery aircraft 100 further comprises a cradle 500 extending from the tail structure 112 at the aft of the aircraft 100 and generally along the central axis of the aircraft 100.

The cradle 500 provides a surface or surfaces 505 which is or are arranged to substantially contact a corresponding surface of the re-entry vehicle R, and subsequently couple thereto. More particularly, the cradle 500 comprises a pair of parallel beams which define between them a space into which the re-entry vehicle may occupy and be coupled to. As such the inner surface of each beam provide the surface 505 for contacting and coupling to the re-entry vehicle; the starboard beam couples to the starboard side of the re-entry vehicle R and the port beam couples to the port side of the re-entry vehicle R. The beams and the surfaces 505 extend backwards from the aft or the aircraft to a distance sufficient to meet the centre of gravity of the re-entry vehicle -4 -R. As such, the length of the beams is approximately half to two thirds of the length of the re-entry vehicle R. Depending on the re-entry vehicle, this length may therefore be between 2 and 7 meters.

Figure lb shows the re-entry vehicle R coupled to the cradle 500.

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 re-entry vehicle R and aligned with the azimuthal direction of the anticipated glide/flight path, and then commences a steep descent of approximately 15 to 20 degrees at a steady indicated airspeed. Then as a re-entry vehicle R descends from space into the atmosphere, and reaches the altitude of the recovery aircraft 100, the re-entry vehicle R glides onto the cradle 500, contacting the surfaces 505, and then couples to the recovery vehicle 100. Once coupled, the recovery aircraft 100 may pull out of the dive to level flight and then transit to any suitable landing site in range.

Referring to Figure 2a, there is shown a further adaptation of the aircraft whereby a tow line 550 extends from the aft of the aircraft 100 and is configured to attach, at its distal end 555, to the re-entry vehicle R. The tow line 550 is provided at a motorised spool (not shown) and is operable to be paid out or drawn in. The tow line 550 may extend to a length of of 500m to 1500m, or 750m to 1250m, or lkm behind the aircraft 120. The tow line 50 is in the form of a cable formed, for example, from a steel. As an alternative to steel, the tow line may be formed of a polymeric material with an equivalent or comparable tensile strength (e.g. a manufactured fibre spun from a liquid-crystal polymer such as VectranTm).

In operation, a recovery vehicle 100 provided with a tow line 550 first manoeuvres to the anticipated altitude, point and direction as would a recovery aircraft 100 without a tow line 550. However, in operation the tow line 550 variant aircraft additionally pays out the tow line 550 (which is in normal flight stored in a wound-in condition) during or prior to the 15 to 20 degree dive. Thus, as the re-entry vehicle R approaches the general altitude of the recovery vehicle 100, it glides (or flies using thrust T from on board rocket motors) to the distal end 555 of the tow line 550 whereupon the re-entry vehicle R couples to the tow line 550. -5 -

Once coupled to the tow line 550, the tow line 550 and connected re-entry vehicle R can be wound in until the re-entry vehicle R is coupled to the cradle 500. Once coupled, the recovery aircraft 100 can pull out of the dive and then transit to any suitable landing site.

Referring to Figure 3 there is shown an empennage or tail structure 113 of a further recovery aircraft 102 having a cradle 502.

Tail structure 113 is a T-tail structure. Such a structure comprises a tail fin 113a extending vertically from the fuselage of the aircraft 102 at the aft and terminating at a distal surface (shown as dashed line 113c). However, the T-tail further comprises a horizontal stabiliser 113b extending laterally from the distal surface 113c, to the port and starboard.

Cradle 502 has in common with cradle 500 a mount portion in the form of a pair of aftward extending beams, shown here as triangular members 510a and 510b, but further comprises a dynamically tuned structure (520, 530) for reducing the peak mechanical stresses as the re-entry vehicle R contacts and couples to the cradle 502.

The dynamically tuned structure comprises a trap portion in the form of a tray 520 which comprises an upper surface 505 for contacting the re-entry vehicle R. The tray 520 is suspended from the triangular members 510a and 510b on a set of tuned elements 530. Tuned elements 530 comprise spring elements and damping elements.

The tray 520 protrudes from the mount portion 510a and 510b such that as a re-entry vehicle R approaches the cradle 502, it tends to mate first with the surface of the tray 520 whereupon continued motion of the re-entry vehicle R towards the mount portion 510a and 510b causes displacement of the tray 520 towards the mount portion 510a and 510b, which tends to decelerate the docking of the re-entry vehicle R as tuned elements 530 are strained. Thus the re-entry vehicle R can be safely guided onto the coupling surfaces of the cradle 502.

Referring to Figure 4 a method of recovering a re-entry vehicle R is shown. -6 -

At step S2 it is provided to fly a recovery aircraft comprising a cradle. At step 54 it is provided to accept or guide the re-entry vehicle onto the cradle of the recovery aircraft. Step S3 may occur optionally simultaneously with step S4, and may involve using the propulsive capability (or thrust T) of the re-entry vehicle R, to assist with the guidance of the re-entry vehicle R to the recovery aircraft.

Referring to Figure 5, sub-steps for achieving step S2 are shown.

At step 521 the recovery aircraft ascends to a point on or above an anticipated flight path of a re-entry vehicle. Typically this will be at an altitude of approximately 12,000m (40,000 feet). At step S22 the recovery aircraft aligns its azimuth flight direction to that of the anticipated azimuth flight direction of the re-entry vehicle. At step 523 the recovery aircraft descends at or between 15 and 20 degrees thereby tending to match the attitude glide path angle of the re-entry vehicle R. 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 system can therefore be absent their own undercarriage and so can be of reduced size, complexity and weight.

The provision of the cradle enables a stable and/or readily tuned mechanical structure for connecting to the re-entry vehicle.

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. -7 -

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 provided, the T-tail structure 113 can tend to reduce the disturbance of the airflow around the re-entry vehicle R as it docks. This can reduce the complexity of the alignment and docking operation.

A communication system may be provided between the re-entry vehicle R and the recovery aircraft 100 or 102 such that the docking can be coordinated. This communication system may transmit and receive signals to facilitate human interaction between the vehicles, or to facilitate interaction between autonomous systems. Such a system may provide that the recovery aircraft is able to instruct or control the propulsion system of the re-entry vehicle.

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, all of which have a T-tail tailplane) 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 '1X\P 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. -8 -

Claims

CLAIMSA recovery aircraft comprising: a cradle extending back from the aft of the recovery aircraft onto which a re-entry vehicle may dock.
A recovery aircraft according to claim 1 wherein the recovery aircraft comprises a tailplane with one vertical tail fin and two horizontal tail fins formed in a T-tail configuration, a cruciform configuration or a fuselage mounted configuration, and wherein the cradle extends aftwards from a region at the base of the tailplane. 3.
A recovery aircraft according to claim 1 or claim 2 wherein the cradle comprises an upper surface for fastening to an underside of the nose of a re-entry vehicle.
A recovery aircraft according to any one of claims 1, 2, or 3, wherein the cradle extends aftwards from the fuselage of the recovery aircraft by length predetermined with reference to a re-entry vehicle so as to be equal to or greater than the distance between the nose and to the centre of gravity of said re-entry vehicle.
A recovery aircraft according to any of the preceding claims wherein the cradle 30 extends a distance between 5 and 10m aftwards of the recovery aircraft. -g -
A recovery aircraft according to any of the preceding claims comprising: a tow line, extending aftwards and which may selectively extend or retract. 7.
A recovery aircraft according to claim 6 wherein the tow line comprises: an attachment for fastening to a re-entry vehicle. 8.
A recovery aircraft according to claim 6 or claim 7 wherein the tow line can extend backward of the recovery aircraft a maximum distance in the range of 500m to 1500m.
A recovery aircraft according to claim 6, 7 or 8 wherein the tow line can extend backward of the recovery aircraft a maximum distance in the range of 750m to 1250m. 10.
A recovery aircraft according to any of the preceding claims wherein the cradle comprises: a mount portion fastened to the recovery vehicle tail and extending therefrom a trap portion for selectively attaching to a re-entry vehicle; and a shock absorbent mounting interconnecting the mount portion and the trap portion.
11. A method of coupling a re-entry vehicle to a recovery vehicle while both are in flight comprising: - providing a cradle at the aft of the recovery vehicle for selective engagement of the re-entry vehicle; - manoeuvring the re-entry vehicle onto the cradle; and - engaging the cradle to effect the coupling.
12. A method according to claim 11 wherein - the cradle is provided with a variable length tow, - manoeuvring the re-entry vehicle onto the cradle comprises: o extending the tow; o coupling the tow to the re-entry vehicle; and o drawing in the tow towards the cradle.
13. A method according to 12 wherein -extending the tow comprises extending a tow line from the aircraft.
14. A method according to claim 13 wherein extending the tow comprises extending the tow line to a distance of between 500m and 1500m behind the recovery vehicle.
15. A method according to any one of claims 11 to 14 wherein - manoeuvring the re-entry vehicle onto the cradle comprises utilising a propulsion system of the re-entry vehicle.