SUPPORTING WING STRUCTURE FOR AN AIRCRAFT, AND AIRCRAFT HAVING SUCH A SUPPORTING WING STRUCTURE

Abstract

A supporting wing structure for an aircraft, in particular for a load-carrying and/or passenger-carrying aircraft, preferably an aircraft in the form of a vertical take-off and landing multicopter having a plurality of electrically driven rotors which are disposed in a distributed manner. The supporting wing structure has a plurality of struts. A first number of the struts are at least largely disposed in a first direction, while a second number of the struts are at least largely disposed in a second direction, the second direction being oriented orthogonal to the first direction. At least the struts of the second number have an aerodynamic profile in cross section, and/or in the struts are connected to one another at least in pairs between neighboring struts by a connecting structure, preferably from individual connecting segments, and the connecting structure or the connecting segments have an aerodynamic profiling. Furthermore an aircraft is provided equipped with such a supporting wing structure.

Claims

1. A supporting wing structure (3) for an aircraft (1), said supporting wing structure comprising: a plurality of struts (4, 4a, 4b), a first number of the struts (4a) are primarily disposed in a first direction (R1), and a second number of the struts (4b) are primarily disposed in a second direction (R2), said second direction (R2) being oriented so as to be orthogonal to the first direction (R1), at least the struts (4b) of the second number have an aerodynamic profile in cross section, and the struts (4, 4a, 4b) that extend between neighboring ones of the struts (4, 4a, 4b) are connected to one another at least in pairs by a connecting structure, and the connecting structure has an aerodynamic profiling.

2. The supporting wing structure (3) as claimed in claim 1, wherein at least the struts (4b) of the second number are disposed substantially in a common plane (E).

3. The supporting wing structure (3) as claimed in claim 1, wherein the aerodynamic profile is configured for generating a lifting force.

4. The supporting wing structure (3) as claimed in claim 1, wherein the first direction (R1) is substantially in alignment with a forward flight direction of the aircraft (1).

5. The supporting wing structure (3) as claimed in claim 2, wherein the aerodynamic profile has a lift-to-drag ratio which, in an incident flow onto the struts (4b) of the second number at an angle in an angular range of 15<<+15, in terms of an extent of the plane (E), is substantially constant.

6. The supporting wing structure (3) as claimed in claim 1, wherein the aerodynamic profile has a relative profile thickness d/l of more than or equal to 0.2, where d is a profile thickness and l is a profile length.

7. The supporting wing structure (3) as claimed in claim 2, wherein the aerodynamic profile on a lower side of the plane (E) has an approximately S-shaped external contour.

8. The supporting wing structure (3) as claimed in claim 2, wherein the aerodynamic profile on a lower side of the plane (E) on a rear side thereof that faces away from a forward flight direction has an external contour with a concave region (KB).

9. The supporting wing structure (3) as claimed in claim 2, wherein the aerodynamic profile is configured asymmetrical with respect to the plane (E), and is configured with at least one of: an approximately S-shaped trend on the lower side thereof, a partially convex and partially concave trend on the lower side thereof, a relative flat nose (FN) with a relatively large curvature radius, a relatively large profile thickness, d/l>0.2, or a concave region (KB) in a rear lower portion.

10. The supporting wing structure (3) as claimed in claim 1, wherein the aerodynamic profile is configured in an external cladding (4) of the struts (4b) of the second number, or a main body of the struts (4b) of the second number are shaped on an external profile thereof with the aerodynamic profile.

11. The supporting wing structure (3) as claimed in claim 2, wherein the struts (4a) of the first number have a symmetrical profile with respect to the plane (E).

12. The supporting wing structure (3) as claimed in claim 11, wherein the symmetrical profile is configured in an external cladding (4) of the struts (4, 4a) of the first number, or a main body of the struts (4a) of the first number are shaped on an external profile thereof with the symmetrical profile.

13. The supporting wing structure (3) as claimed in claim 1, wherein the struts (4a) which are oriented in a first angular range from approximately 45 to approximately +45 about the first direction (R1) are configured as struts (4a) of the first number.

14. The supporting wing structure (3) as claimed in claim 13, wherein the struts (4b) which are oriented in a second angular range of approximately +45 to approximately +135 and approximately +225 to approximately +315 to the first direction (R1) are configured as struts (4b) of the second number.

15. The supporting wing structure (3) as claimed in claim 14, wherein the struts (4a) which are oriented in a third angular range of approximately +135 to approximately +225 to the first direction (R1) are configured as struts (4a) of the first number.

16. The supporting wing structure (3) as claimed in claim 15, wherein the remaining struts (4b) are configured as struts of the second number.

17. The supporting wing structure (3) as claimed in claim 16, wherein the struts (4a) of the first number in the first or the third angular range have in each case an identical aerodynamic profile.

18. The supporting wing structure (3) as claimed in claim 16, wherein the struts (4a) of the first number in the first or the third angular range have an aerodynamic profile which differs from one strut to the other strut.

19. The supporting wing structure (3) as claimed in claim 1, wherein the struts (4, 4a, 4b) emanate from a central fastening structure (la) and are fastened by respective first ends of said struts (4, 4a, 4b) to the central fastening structure (la).

20. The supporting wing structure (3) as claimed in claim 1, wherein the struts (4, 4a, 4b), at respective second free ends thereof, between neighboring struts (4, 4a, 4b) are connected to one another at least in pairs by the connecting structure.

21. The supporting wing structure (3) as claimed in claim 20, wherein the connecting structure has an aerodynamic profiling.

22. The supporting wing structure (3) as claimed in claim 1, wherein the struts (4, 4a, 4b) are configured to branch out in an arborescent manner.

23. The supporting wing structure (3) as claimed in claim 1, wherein the struts (4, 4a, 4b) are configured to support drive units (2, 6) of the aircraft, said drive units (2, 6) having in each case at least one rotor (6) and one motor unit (2) for driving the rotor (6).

24. An aircraft (1), comprising a plurality of electrically driven rotors (6) which are disposed in a distributed manner and the supporting wing structure (3) as claimed in claim 1 that supports at least the rotors (6).

25. The aircraft (1) as claimed in claim 24, further comprising a plurality of motors (2) configured to drive the rotors (6) disposed on the supporting wing structure (3).

26. The aircraft (1) as claimed in claim 25, wherein at least some of the rotors (6) are disposed above a common plane (E) in which at least the struts (4b) of the second number are disposed.

27. The aircraft (1) as claimed in claim 26, further comprising at least one of a passenger cockpit (5) or a load receptacle disposed below the common plane (E).

28. The aircraft (1) as claimed in claim 26, wherein the aircraft is a vertical take-off and landing multicopter.

29. The supporting wing structure (3) as claimed in claim 1, wherein the connecting structure comprises connecting segments (3a) which have the aerodynamic profiling.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Further properties and advantages of the invention are derived from the description hereunder of exemplary embodiments with reference to the drawings in which:

[0064] FIG. 1 shows an aircraft without rotors in a view from above, looking toward the supporting wing structure;

[0065] FIG. 2 shows the aircraft from FIG. 1 with rotors, in a lateral view;

[0066] FIG. 3 shows the aircraft from FIG. 2 in the forward flight;

[0067] FIG. 4 shows a previously known aerodynamic profile having a relatively large stretch;

[0068] FIG. 5 shows an aerodynamic profile having a relatively large profile height;

[0069] FIG. 5A shows the profile in FIG. 5a in a more precise illustration;

[0070] FIG. 6 shows a graphic illustration of the correlation between the lift-to-drag ratio and the incident flow angle; and

[0071] FIG. 7 shows a potential design embodiment of a strut cladding according to the invention.

DETAILED DESCRIPTION

[0072] FIG. 1 shows a load-carrying and/or passenger-carrying aircraft 1 in the form of a vertical take-off and landing multicopter produced by the applicant, having a plurality of electrically driven rotors which are disposed in a distributed manner and which are not illustrated for reasons of clarity in FIG. 1. Reference sign 2 identifies the associated motor units or (electric) motors, wherein one rotor is preferably assigned to each motor 2. The aircraft 1 possesses a supporting wing structure 3 for the motor/rotors, said supporting wing structure 3 having a plurality of struts 4 which are disposed substantially in a plane E (parallel to the rotor plane) and, emanating from a central fastening structure 1a, branch out in an arborescent (Y-shaped) manner toward the outside. FIG. 1 shows a view from above, looking onto said plane E. On the external periphery of the supporting wing structure 3, neighboring struts 4 in the region of the free ends thereof are connected in pairs by way of connecting structures in the form of segments 3a which are bent in the manner of divided circles. A passenger cockpit 5 is disposed below the plane E. A first number of the struts 4 are at least largely disposed in a first direction R1 in or parallel to the plane E, said first direction R1 coinciding with a forward flight direction of the aircraft 1 (cf. the x-coordinate shown in FIG. 1). Said struts in FIG. 1 are identified with the reference sign 4a. In contrast, a second number of the struts 4 are at least largely disposed in a second direction R2 in or parallel to the plane E, said second direction R2 being oriented so as to be orthogonal to the first direction R1 (y-coordinate). Said struts in FIG. 1 are identified by the reference sign 4b. At least the struts 4b of the second number have an aerodynamic profile in cross section, this being discussed in yet more detail hereunder. The disposal of the struts 4 is symmetrical in terms of the x-axis, which is why the struts 4 are identified only in one half of the illustration.

[0073] FIG. 2 shows the aircraft 1 from FIG. 1 including rotors 6 of which only a few are identified for reasons of clarity, said aircraft 1 being in a hovering flight. The rotors 6 in the hovering flight generate the downdraft illustrated by arrows at the reference sign A, and on account thereof download, when the downdraft A interacts with structural parts of the aircraft 1, for example with the supporting wing structure 3, or the struts 4 and the segments 3a, respectively.

[0074] FIG. 3 shows the aircraft 1 from FIG. 2 in the forward flight. In order to change from the vertical (hovering) flight shown in FIG. 2 to a horizontal flight state according to FIG. 3, the entire aircraft 1 in the case of the vertical take-off and landing multicopter shown is incited to tilt forward by correspondingly regulating the rotating speeds of different rotors 6. On account thereof, the incident flow angle of the incident flow of air onto the supporting wing structure 3 in terms of the (rotor) plane E changes, as is illustrated. The reference sign v identifies the flight speed of the aircraft 1, or the speed of the incident flow of air. The arrows at the reference sign A symbolize the resulting air flow in the region of the rotors 6 (which are at the front in the flight direction). By virtue of the conjoint effect of the forward tilt of the aircraft 1 and of the downward airflow caused by the rotors 6 an effective incident flow angle +x consequently results in the region of the supporting wing structure 3, or of the struts 4, respectively.

[0075] According to the invention, the supporting wing structure 3, or at least some of the struts 4, 4a, 4b present therein, respectively, is/are now to be provided with an aerodynamic profile, or to have such an aerodynamic profile, respectively, such that the air resistance on account of the supporting wing structure 3, or the struts 4, 4a, 4b, respectively, is minimized, on the one hand. On the other hand, the aerodynamic profile in a forward flight of the aircraft 1 is according to the invention to generate a lifting force so as to support the movement in flight.

[0076] This preferably relates to the struts 4b of the second number (cf. FIG. 1), while the struts 4a of the first number which are oriented approximately in the forward flight direction R1 can have an aerodynamically neutral profile, for example an elliptic profile, so as to generate as little aerodynamic resistance as possible.

[0077] By virtue of the above-mentioned symmetry of the aircraft 1, struts 4 in specific ranges of an angle defined in the plane E furthermore preferably possess profiles which are identical about a vertical axis of the aircraft 1, wherein the value 8=0 corresponds to the forward flight direction R1.

[0078] In particular, the struts 4 in the front range (45<<45) as well as in the rear range (135<<225) preferably have similar or identical profiles, while the struts 4, deviating therefrom, in the respective lateral ranges to the right (45<<135) and to the left (225<<315) of the cockpit 5 may have other profiles which again however are mutually similar.

[0079] While FIG. 4 shows a conventional aerodynamic profile which has a relatively large stretch l/d, an aerodynamic profile which is preferably used in the context of the invention is illustrated in FIG. 5 (cf. also FIG. 5A). Said aerodynamic profile preferably used is distinguished by the following features which may be developed collectively or individually as well as to a greater or lesser extent: an approximately S-shaped trend on the lower side (so-called S-feature) having a partially convex and partially concave trend; flat nose FN having a large curvature radius (in the left lower region); a relatively large profile thickness: d/l>0.2, preferably >0.3. Especially the cavity (concave region KB) in the rear lower region by virtue of a controlled separation of the flow has a favorable effect on the desired aerodynamic behavior.

[0080] When comparing the profiles according to FIG. 4 and FIG. 5 or 5A, respectively, it furthermore becomes obvious that the profile according to Figure s5, 5a is also shorter in absolute terms (1<1). In particular in a vertical take-off and landing aircraft such as the Volocopter multicopter from the company of the applicant, there is specifically the already mentioned necessity of achieving an ideally minor stretch of the profile for the hovering flight or the vertical flight, respectively, (cf. FIG. 2), so as to minimize the parasitic surface which is exposed to the downdraft A.

[0081] The profile according to FIG. 5 is illustrated even more precisely and with corresponding coordinate indications in FIG. 5a. The already mentioned optimum design point O (nominal incident flow parallel to the x-axis (abscissa)) lies in the origin of the coordinate system shown.

[0082] FIG. 6 schematically shows a change in the lift-to-drag ratio (ratio of the lift L to air resistance D:E=L/D) by way of the incident flow angle for the profile according to Figure s5, 5a at the reference sign b. The curve at the reference sign a for comparison shows a trend of the lift-to-drag ratio E (L/D) known from the prior art in terms of the incident flow angle . It can be seen herein that the previously known profile by way of a lift-to-drag ratio trend according to curve a may indeed have high (higher) lift-to-drag ratio in absolute terms, but only across a relatively small range of the incident flow angle .

[0083] As opposed thereto, in the case of b the corresponding trend for the profile according to FIGS. 5, 5A is shown for the profile proposed here. A relatively flat profile of the lift-to-drag ratio across a comparatively large range of the incident flow angle results here, that is to say that the profile has a substantially constant lift-to-drag ratio across wide ranges of a, which is appropriate for the circumstances shown in FIG. 3 and ensures practically constant aerodynamic conditions even at variable angles of inclination, or variable relative angles between the airflow and the supporting wing structure, respectively. O.sub.a and O.sub.b identify the respective optimum design points.

[0084] Proceeding from the profile in FIG. 5 or FIG. 5A, FIG. 7 shows a potential design embodiment of the supporting wing structure 3 and of the struts 4 or 4b, respectively, in cross section. The actual strut or supporting structure 4 (especially for these struts 4b) according to this design embodiment has a circular cross-section and is disposed in the interior. Said strut or supporting structure 4 is externally surrounded by a cladding 4, said cladding 4 having the shape of the profile according to FIG. 5, 5A. In this way, conventional components can be used and be subsequently aerodynamically improved. Alternatively, a main body, especially of the struts 4b of the second number, can be shaped according to the aerodynamic profile directly on the external surface of said main body.

[0085] The connecting structures in the form of the segments 3a bent in the manner of a divided circle (cf. FIG. 1) can also have an aerodynamic profiling, as mentioned, preferably in the portions which in the forward flight direction are disposed in the front range, for example for 45<<45, or else in the rear range (135<<225). Regions of the segments 3a bent in the manner of a divided circle that have an elliptic cross section can be disposed therebetween. The transitions between the profile shapes can be configured so as to be continuous (flowing). The same applies to the struts 4 (4a, 4b). Various branches of struts 4 which branch out in an arborescent manner may have dissimilar profiles. The profiles can be more or less pronounced, depending on the angular position f3.

[0086] In principle, only a few different angles relative to the first direction R1 exist for the struts 4 in the aircraft according to FIG. 1, specifically 0 (or 180, respectively) 60 and 120 for the external struts 4, as well as 30, 90 and 150 for the internal struts. Correspondingly, there are preferably only a few dissimilar profiling shapes which can depend in particular on the mentioned angle and/or on the location of attachment in the aircraft (front, rear, side).