A landing pad for a vertical take-off and landing aircraft

Abstract

A landing pad 500 for a vertical take-off and landing aircraft, the landing pad extending in a first plane 510 and having a landing pad area 520, wherein the landing pad comprises: a landing surface 530 occupying a first proportion of the landing pad area, wherein the first proportion comprises between 80% and 95% of the landing pad area; and a plurality of apertures 540 occupying a second proportion of the landing pad area, wherein the second proportion comprises between 5% and 20% of the landing pad area; wherein the plurality of apertures is adjustable so as to vary the second proportion of the landing pad area relative to the first proportion of the landing pad area. A further landing pad is also claimed. The apertures maybe variable in size and or number, the landing pad may comprise upper 532 and lower 534 layers where the apertures vary between layers in number, size and positioning

Description

VTOLs including eVTOLs and conventional helicopters generate air downwash and outwash when close to a surface such as one provided for landing or take-off. VTOLs, especially eVTOLs, often use multiple rotors or propellors, which may result in greater downwash velocities than for an equivalent helicopter that might have only a single rotor. Air downwash and outwash may have significant impacts in the region around a landing or take-off area. Care needs to be taken to minimise the negative impacts of downwash and outwash in the region of a landing or take-off area without compromising ability of the VTOL to take-off and land safely and efficiently. Summary of the disclosure Against this background, there is provided a landing pad for a vertical take-off and landing aircraft, the landing pad extending in a first plane and having a landing pad area, wherein the landing pad comprises: a landing surface occupying a first proportion of the landing pad area, wherein the first proportion comprises between 80% and 95% of the landing pad area; and a plurality of apertures occupying a second proportion of the landing pad area, wherein the second proportion comprises between 5% and 20% of the landing pad area; wherein the plurality of apertures is adjustable so as to vary the second proportion of the landing pad area relative to the first proportion of the landing pad area. In this way, downwash and outwash arising from a VTOL landing, taking off, or hovering may be more effectively dissipated by the plurality of apertures of the second proportion of the landing pad area. This in turn means that the impact of downwash and outwash close to the aircraft is reduced and the region of impact of downwash and outwash is also reduced. Furthermore, the landing surface of the first proportion of the landing pad area is sufficient to prevent the downwash from propagating fully to the volume beneath the landing pad. Optionally, each aperture of the plurality of apertures has a maximum dimension of between 5 mm and 50 mm, preferably 10 mm to 20 mm, most preferably 10 mm. Optionally, the plurality of apertures is adjustable by adjusting the size of at least a subset of the plurality of apertures. Optionally, the plurality of apertures is adjustable by adjusting a number of at least a subset of the plurality of apertures. Optionally, the landing surface comprises an upper layer and a lower layer, wherein the lower layer is movable relative to the upper layer so as to adjust the first proportion relative to the second proportion. Optionally, the landing pad comprises a first zone and a second zone, and wherein the first proportion and the second proportion are different in the first zone relative to the second zone. In this way, the zones may be different beneath the rotors of a VTOL relative to elsewhere. Optionally, the first proportion in the first zone is controllable independently of the first proportion in the second zone. In this way, the zones may be adapted independently depending on a type and orientation of VTOL. Optionally, the upper layer lies in the first plane and the lower layer lies in a second plane parallel to the first plane. Optionally, the lower layer is movable relative to the upper layer by movement of the lower layer in the second plane or movement of the upper level in the first plane. Optionally, the lower layer is movable relative to the upper layer by movement of the lower layer by tilting relative to the first plane. Optionally, each aperture comprises a circular opening in the landing pad. Optionally, the first proportion comprises 85% to 95% of the landing pad area; and the second proportion comprises 5% and 15% of the landing pad area. Optionally, the landing pad further comprises a deflector that extends around the landing surface and projects out of the first plane. Optionally, the deflector projects perpendicular to the first plane. Optionally, the landing pad extends up to 200 mm out of the first plane. Optionally, the deflector comprises a deflector panel and deflector apertures in the deflector panel. Optionally, at least some of the apertures are shaped to deflect or aid mixing of airflow. In a second aspect of the disclosure, there is provided a landing structure comprising the landing pad previous described and a cavity beneath the landing pad. In this way, the cavity may assist in dissipation of downwash and outwash. Optionally, the cavity has a cavity volume and each aperture has an aperture volume, wherein the cavity volume is at least 1,000 times the aperture volume. Optionally, the cavity is vented to atmosphere. Optionally, the landing structure comprises a core assembly beneath the landing pad such that the landing pad is elevated by the core assembly. In a third aspect of the disclosure, there is provided airport infrastructure comprising the landing structure as previously described and one or more modules for passenger use or aircraft parking, wherein the one or modules is located adjacent to the landing structure and the landing pad is elevated above the one or more modules such that the landing pad is the highest part of the airport infrastructure. In a fourth aspect of the disclosure, there is provided a landing pad for a vertical take-off and landing aircraft, the landing pad having a landing pad area, wherein the landing pad comprises: a landing surface occupying a first proportion of the landing pad area, wherein the first proportion comprises 80% to 95% of the landing pad area; and a plurality of apertures occupying a second proportion of the landing pad area, wherein the second proportion comprises 5% and 20% of the landing pad area; wherein the landing pad comprises a first zone and a second zone, and wherein the first proportion and the second proportion are different in the first zone relative to the second zone. Optionally, the first proportion comprises 85% to 95% of the landing pad area; and the second proportion comprises 5% and 15% of the landing pad area. Brief description of the drawings Figure 1 shows a first example of a vertical airport infrastructure comprising an elevated landing pad; Figure 2 shows a second example of a vertical airport infrastructure comprising elevated landing pads; Figure 3 shows a third example of a vertical airport infrastructure comprising an elevated landing pad; Figure 4 shows a landing pad comprising a landing surface and a plurality of apertures, in both plan view and side on cross sectional view; Figure 5 shows the landing pad of Figure 4 with the plurality of apertures adjusted relative to Figure 4; Figure 6 shows the landing pad of Figures 4 and 5 with the plurality of apertures adjusted relative to Figures 4 and 5; Figure 7a shows vorticity distribution in outwash created by an aircraft hovering above a flat impermeable ground plane in a perspective view; Figure 7b shows vorticity distribution in outwash created by an aircraft hovering above a flat impermeable ground plane in a front view; Figure 8a shows vorticity distribution in outwash created by an aircraft hovering above an elevated permeable landing pad in a perspective view; Figure 8b shows vorticity distribution in outwash created by an aircraft hovering above an elevated permeable landing pad in a front view; Figure 9a shows a snapshot of the velocity of outwash created by an aircraft hovering above a flat impermeable ground plane in a plan view; Figure 9b shows a snapshot of the velocity of outwash created by an aircraft hovering above an elevated permeable landing pad in a plan view; Figure 10 shows a fourth example of a vertical airport infrastructure which is similar to that for the third example of Figure 3 and which also includes an upstand at a periphery of the landing pad; and Figure 11 shows a variation on the landing pad of Figures 4, 5 and 6 showing a less regular aperture pattern. Detailed description Figure 1 shows a first example of a vertical airport infrastructure 10 comprising a landing pad 12 as previously disclosed in commonly owned WO2022263512. Figure 2 shows a second example of a vertical airport infrastructure 100 comprising landing pads 130, 150, as previously disclosed in commonly owned WO2024008750A1. Figure 3 shows a third example of a vertical airport infrastructure 1000 comprising a landing pad 120, as previously disclosed in commonly owned WO2024008750A1. In each of the examples of Figures 1 to 3 there is provided a landing pad 12, 120, 130, 150, for a vertical take-off and landing aircraft. The landing pad 12, 120, 130, 150 may be vertically movable between a lower level (e.g. as shown for landing pad 130 in Figure 2) and an upper level (e.g. as shown for landing pad 12 in Figure 1, for landing pad 150 in Figure 2, and for landing pad 120 in Figure 3). The landing pad 12, 120, 130, 150 may be positioned at the upper level for take-off and landing movements. The landing pad 12, 120, 130, 150 may be positioned at the lower level for loading and unloading and / or for movement of a VTOL into an adjacent hangar space. A lift structure, such as a link lift, may be provided to facilitate movement of the landing pad 12, 120, 130 between the upper level and the lower level. In the case of the second example (Figure 2), which has both a first landing pad 130 and a second landing pad 150, it may be that the first landing pad 130 is vertically movable and the second landing pad 150 is static at the upper level. The vertical airport infrastructure 10, 100, 1000 of the first, second and third examples further includes a core assembly beneath the landing pad 12, 120, 130, 150. In this way, the landing pad 12, 120, 130, 150 is elevated (at least when at the upper level) relative to the ground level. The vertical airport infrastructure 10, 100, 1000 of the first, second and third examples further includes one or more modules located adjacent to the landing pad. Such modules may, for example, comprise a passenger area or space for aircraft parking. The one or more modules may have a height which is the same as or less than the height of the landing pad 12, 120, 130, 150 when at the upper level. In this way, it may be that there are no elements of the vertical airport infrastructure 10, 100, 1000 that extend above the height of the landing pad 12, 120, 130, 150 when at the upper level. In the first example of Figure 1, the one or more modules may comprise a single annular space beneath one or more cladding segments 42, one or more of which cladding segments 42 may be raisable to allow access into the module from outside the vertical airport infrastructure 10. In the second example of Figure 2, the one or more modules may comprise passenger circulation space, hangar space, and aircraft bays 250 that may or may not have a roof above. The second example further comprises a plurality of landing areas 160, 170, 180 at ground level outside a perimeter of the aerodrome structure 100. These are merely illustrative of further options for increasing aerodrome capacity. In the third example of Figure 3, the one or more modules may comprise one or more aircraft hangar modules 400 (which may comprise more than one hangar 410 stacked vertically) and one or more passenger facility modules 500. In all of the examples of Figures 1 to 3, there are no elements that extend to a height above the landing pad 12, 120, 130, 150 when it is positioned at the higher level. In this way, the landing pad 12, 120, 130, 150 of Figures 1 to 3 is the highest part of the airport infrastructure. Figure 4 show a highly schematic representation of an example of a landing pad 500 in isolation from vertical airport infrastructure 10, 100, 1000. Although the example landing pad 500 is shown as being square, it may have any appropriate shape. In one implementation, the landing pad 500 may form a square of 32 m x 32 m. In accordance with the disclosure, the landing pad 500 extends in or parallel to a first plane 510 and has a landing pad area 520. The landing pad 500 comprises a landing surface 530 and a plurality of apertures 540. The landing surface 530 occupies a first proportion of the landing pad area 520 while the plurality of apertures 540 occupies a second proportion of the landing pad area 520. The apertures 540 are distributed across the landing surface 530. The first proportion comprises between 80% and 95% of the landing pad area 520. The second proportion of the landing pad area comprises between 5% and 20% of the landing pad area 520. (Note that Figure 4 is not to scale.) The plurality of apertures 540 may be adjustable so as to vary the second proportion of the landing pad area 520 relative to the first proportion of the landing pad area 520. Any appropriate provision may be made for adjusting the first proportion relative to the second proportion. Each aperture 540 of the plurality of apertures 540 may have a a maximum dimension of between 5 mm and 20 mm. In this way, the benefits in relation to downwash and outwash are realised whilst minimising risk that parts of an aircraft or a passenger may enter the apertures 540. The size, location and distribution of apertures 540 may be selected to benefit specific vertical take-off and landing aircraft. For example, the size, location and distribution of apertures 540 may reflect the position and size of rotors on specific vertical take-off and landing aircraft. In one implementation, the landing surface 530 may comprise an upper layer 532 and a lower layer 534. The upper layer 532 may be parallel to the lower layer 534. The upper layer 532 may sit in or parallel to the first plane 510. The upper layer 532 may comprise a plurality of upper openings 542 and the lower layer 534 may comprise a plurality of lower openings 544. Each aperture 540 may be formed by a region where an upper opening 542 overlaps with a lower opening 544. The upper layer 532 and / or the lower layer 534 may comprise an aluminium sheet. The thickness of each aluminium sheet may be less than 10 mm. Alternatively, the upper layer 532 and the lower layer 534 may comprise a steel sheet. Alternatively, the upper layer 532 and the lower layer 534 may comprise any suitable substantially non-permeable material. Direction controlling elements (not shown) may be provided at or towards the underside of the apertures 540. In this way, air that travels through the apertures may be directed away from particular areas under the landing pad 500. In Figure 4, the lower openings 544 in the lower layer 534 align with the upper openings 542 in the upper layer 532 such that the boundary of each aperture 540 is the same as the boundary of its corresponding lower opening 544 and its corresponding upper opening 542. The lower layer 534 may be movable relative to the upper layer 532 so as to adjust an extent to which the lower openings 544 overlap with the upper openings 542. Figure 5 shows the landing pad 500 of Figure 4 wherein the lower layer 534 has moved laterally (in a direction from right to left in the plane of the page) relative to the upper layer 532 by comparison with their relative positions in Figure 4. In this way, the upper openings 542 no longer overlap fully with the lower openings 544 such that the apertures 540 occupy a smaller area than the area of the upper openings 542 and a smaller area than the area of the lower openings 544. Figure 6 shows the landing pad 500 of Figures 4 and 5 wherein the lower layer 534 has moved laterally (in a direction from top to bottom in the plane of the page) relative to the upper layer 532 by comparison with their relative positions in Figure 5. In this way, an area of overlap between each upper openings 542 and its respective lower openings 544 (that is the area of each aperture 540) is reduced further. In these ways, it is possible to vary the first proportion of the landing pad area 520 (that is that which is occupied by the landing surface 530) relative to the second proportion of the landing pad area 520 (that is that which is occupied by the apertures 540). By adjusting the area of the apertures, the second proportion may vary between 5% of the landing pad area and 20% of the landing pad area 520. A corollary of this is that the first proportion may vary between 80% and 95% of the landing pad area 520. (Again, it should be noted that Figures 4, 5 and 6 are not to scale.) Other techniques for adapting the area occupied by the apertures may be equally appropriate. For example, the lower layer 534 may be movable rotationally rather than translationally in the second plane. In another example, the lower layer 534 may be movable out of the second plane in order to vary the proportion of the landing pad area 520 occupied by the apertures. Alternatively, it may be that the upper layer 532 is movable relative to the lower layer 534. In another alternative, rather than providing an upper layer and a lower layer, some or all of the apertures may be provided with a shutter. Other alternative approaches to adapting the area of the apertures are envisaged as falling within the scope of the claims. Figure 7a shows vorticity distribution 3 in outwash created by a vertical take-off and landing aircraft 1 hovering above a flat ground plane 2 without apertures. Figure 7b shows vorticity distribution 4 in outwash created by the same vertical take-off and landing aircraft 1 hovering above the same flat ground plane 2 without apertures. Unlike the landing pads 500 described in relation to Figures 4 to 6, the flat ground plane 2 has no apertures or other downward route through which downwashed and outwashed air may flow, meaning that the only directions that downwashed and outwashed air can be dissipated are laterally and upwards (or a combination of the two). Figure 8a shows vorticity distribution 3 in outwash created by the same vertical take-off and landing aircraft 1 as shown in Figure 7a. Rather than hovering above a flat ground plane 2 without apertures, the vertical take-off and landing aircraft 1 is hovering above a landing pad 500 with apertures, wherein the landing pad 500 is elevated by vertical airport infrastructure 1000. The apertures are such that they occupy 10 % of the area of the landing pad. Figure 8b shows vorticity distribution 4 in outwash created by the same vertical take-off and landing aircraft 1 hovering above the same landing pad 500 with apertures, wherein the landing pad 500 is elevated by vertical airport infrastructure 1000. Comparing Figure 8a with Figure 7a, it will be seen that the outwash is less in the elevated landing pad 500 with apertures relative to flat ground plane 2 without apertures. Similarly, comparing Figure 8b with Figure 7b, it will be seen that the vorticity distribution is less in the elevated landing pad 500 with apertures relative to flat ground plane 2 without apertures. Figure 9a shows a snapshot of the velocity of outwash created by the vertical take-off and landing aircraft 1 hovering above the flat ground plane 2 without apertures. Figure 9b shows a snapshot of the velocity of outwash created by the vertical take-off and landing aircraft 1 hovering above an elevated landing pad 500 with apertures. The apertures are such that they occupy 10 % of the area of the landing pad. Again, comparing Figure 9b with Figure 9a, it will be seen that the velocity of outwash is less throughout Figure 9b than Figure 9a. Figure 10 shows a fourth example of a vertical airport infrastructure which is similar to that for the third example of Figure 3 and which also includes an upstand 121 (also termed a deflector) at a periphery of the landing pad. The upstand 121 has the effect of further altering the downwash and outwash behaviour so as to reduce their impact. The upstand 121 may project perpendicular to the landing pad 500. The upstand 121 may project up to 200 mm out of the first plane, or may project up to 500 mm out of the first plane. Thus the upstand 121 may be the highest element of the vertical airport infrastructure 1000. The deflector may comprise a deflector panel and deflector apertures in the deflector panel. Where present, the deflector apertures may facilitate further dissipation of downwash and outwash. Figure 11 shows a variation on the landing pad of Figures 4, 5 and 6, comprising an aperture pattern that is less regular than that of Figures 4, 5 and 6. By arranging upper and lower openings in different patterns, it is possible to change the vary the size of different apertures differently and to alter the number of apertures by ensuring that it is possible to close some apertures fully. In other arrangements, the landing pad may provide a plurality of zones within the landing pad, wherein the ratio between the first proportion and the second proportion is different as between different zones. The first proportion in a first zone may be controllable independently of the first proportion in a second zone. This may be implemented using a specific irregular arrangement of apertures (per Figure 11) or in another suitable manner. As already described, the size, location and distribution of apertures 540 may be selected to benefit specific vertical take-off and landing aircraft. The differently controllable zones may be adjusted differently to adjust one or more of the size, location and distribution of apertures 540 may reflect the position and size of rotors on specific vertical take-off and landing aircraft in a specific orientation. There is no requirement for the apertures to be distributed evenly across the landing pad. Furthermore, there may be one or more zones where there are no apertures. Although Figures 4, 5, 6 and 11 all show circular upper and lower openings, other shapes of opening are possible and fall within the scope of this disclosure. Whether the landing pad 500 is elevated or not, a cavity is provided beneath the landing pad 500. The cavity may be vented. In the case of an elevated landing pad 500, the cavity may simply be provided by a volume bounded by the core assembly and the landing pad 500. In an event that the landing pad 500 is provided at ground level, the cavity may comprise a pit provided beneath ground level. The cavity volume may be at least 1,000 times the aperture volume. In this way, the cavity acts as a volume sufficiently large that there is minimal resistant to air passing through the apertures and into the cavity. Instead or in addition to the cavity having a volume at least 1,000 times the aperture volume, the cavity may be vented to atmosphere.

Claims

1. A landing pad for a vertical take-off and landing aircraft, the landing pad extending in a first plane and having a landing pad area, wherein the landing pad comprises:a landing surface occupying a first proportion of the landing pad area, wherein the first proportion comprises between 80% and 95% of the landing pad area; anda plurality of apertures occupying a second proportion of the landing pad area, wherein the second proportion comprises between 5% and 20% of the landing pad area;wherein the plurality of apertures is adjustable so as to vary the second proportion of the landing pad area relative to the first proportion of the landing pad area.

2. The landing pad of claim 1 wherein each aperture of the plurality of apertures has a maximum dimension of between 5 mm and 50 mm, preferably 10 mm to 20 mm, most preferably 10 mm.

3. The landing pad of claim 1 or claim 2 wherein the plurality of apertures is adjustable by adjusting the size of at least a subset of the plurality of apertures.

4. The landing pad of claim 1 or claim 2 wherein the plurality of apertures is adjustable by adjusting a number of at least a subset of the plurality of apertures.

5. The landing pad of any preceding claim wherein the landing surface comprises an upper layer and a lower layer, wherein the lower layer is movable relative to the upper layer so as to adjust the first proportion relative to the second proportion.

6. The landing pad of any preceding claim wherein the landing pad comprises a first zone and a second zone, and wherein the first proportion and the second proportion are different in the first zone relative to the second zone.

7. The landing pad of claim 6 wherein the first proportion in the first zone is controllable independently of the first proportion in the second zone.

8. The landing pad of claim 5 or any claim dependent on claim 5 wherein the upper layer lies in the first plane and the lower layer lies in a second plane parallel to the first plane.

9. The landing pad of claim 8 wherein the lower layer is movable relative to the upper layer by movement of the lower layer in the second plane or movement of the upper level in the first plane.

10. The landing pad of claim 5 wherein the lower layer is movable relative to the upper layer by movement of the lower layer by tilting relative to the first plane.

11. The landing pad of any preceding claim wherein each aperture comprises a circular opening in the landing pad.

12. The landing pad of any preceding claim wherein:the first proportion comprises 85% to 95% of the landing pad area; and the second proportion comprises 5% and 15% of the landing pad area.

13. The landing pad of any preceding claim wherein the landing pad further comprises: a deflector that extends around the landing surface and projects out of the first plane.

14. The landing pad of claim 13 wherein the deflector projects perpendicular to the first plane.

15. The landing pad of claim 13 or claim 14 wherein the landing pad extends up to 200 mm out of the first plane.

16. The landing pad of any of claims 13 to 15 wherein the deflector comprises a deflector panel and deflector apertures in the deflector panel.

17. The landing pad of any preceding claim wherein at least some of the apertures are shaped to deflect or aid mixing of airflow.

18. A landing structure comprising the landing pad of any preceding claim and a cavity beneath the landing pad.

19. The landing structure of claim 18 wherein the cavity has a cavity volume and each aperture has an aperture volume, wherein the cavity volume is at least 1,000 times the aperture volume.

20. The landing structure of claim 18 or claim 19 wherein the cavity is vented to atmosphere.

21. The landing structure of any of claims 18 to 20 further comprising a core assembly beneath the landing pad such that the landing pad is elevated by the core assembly.

22. Airport infrastructure comprising the landing structure of any of claims 18 to 21 and one or more modules for passenger use or aircraft parking, wherein the one or modules is located adjacent to the landing structure and the landing pad is elevated above the one or more modules such that the landing pad is the highest part of the airport infrastructure.

23. A landing pad for a vertical take-off and landing aircraft, the landing pad having a landing pad area, wherein the landing pad comprises:a landing surface occupying a first proportion of the landing pad area, wherein the first proportion comprises 80% to 95% of the landing pad area; anda plurality of apertures occupying a second proportion of the landing pad area, wherein the second proportion comprises 5% and 20% of the landing pad area;wherein the landing pad comprises a first zone and a second zone, and wherein the first proportion and the second proportion are different in the first zone relative to the second zone.

24. The landing pad of claim 23 wherein:the first proportion comprises 85% to 95% of the landing pad area; andthe second proportion comprises 5% and 15% of the landing pad area.16

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