Wing arrangement for use in a flapping wing aircraft

Abstract

Wing arrangement for use in a flapping wing aircraft, comprising a strut arrangement (10) comprising a support strut (11) and several support struts (15 to 25) each oriented at an angular interval between 30 degrees and 90 degrees relative to the support strut (11), wherein at least some of the support struts (16 to 24) have a front section (36 to 44), an adjoining connecting section (95 to 105) and an adjoining rear section (45 to 55) and wherein each of the support struts (15 to 25) is fixed to the support strut (11) by the connecting section (95 to 105), and comprising a group of skinning parts (65 to 75) made of an elastic and dimensionally stable film material and connected to the strut arrangement (10).

Description

[0001] The invention relates to a wing arrangement for use in a flapping-wing aircraft.

[0002] From GB 885 273 A an ornithopter with movable wings is known, each of the wings having a rigid front part with a wing cross-section and a flexible rear part which is movable up or down relative to the front rigid part when the wing is moved up or down, the part tapering outwards so that its surface area is greatest at the inner end of the wing and the surface area of ​​the part is greatest at the outer end of the wing. The rear part consists of a number of overlapping flap sections with rigid spars which are connected to the front part 4 and arranged so that the air is trapped under the wing when it is moved downwards, but that the air can pass through the wings from top to bottom when the wing is moved upwards.

[0003] DE 10 2011 013 704 A1 discloses a flapping wing device with a base body, a drive device and a flapping wing, wherein the flapping wing comprises a first and a second wing section and a joint device between the first and the second wing section, wherein the first wing section has a joint means for pivotally mounted on the base body and wherein the drive device is designed to initiate a relative movement between the base body and the flapping wing.

[0004] The invention DE 315 493 A relates to a flapping wing with automatic, elastic twisting to achieve an effect similar to bird flight, wherein the front spar, which is rotatably mounted on the axis of rotation of the main spar located in front of the pressure center of the wing and moved by the drive motor, has a lever arm projecting beyond the pivot point.

[0005] WO 2008 / 128 780 A1 discloses a drive device which is designed to be connectable to a drive on one side and which has a bending element substantially in the shape of a wedge, which has at least two bending sections spaced apart from one another on the drive side, the distance between which decreases in the direction away from the drive and which are coupled in a force-transmitting manner in the region of the end of the bending element facing away from the drive. The bending sections on the drive side are held movable relative to one another substantially along the longitudinal axis of the wedge, and the bending element can be converted into a different curvature pointing in the thickness direction of the flexible impact wing depending on the relative position of the bending sections on the drive side.

[0006] GB 289 829 A discloses a wing for an ornithopter comprising flexible spring-like elements attached to articulated spars connected to the body frame by parallel links, so that when the main spars are moved in a conical path, the wings extend and partially fold, the springs opening and closing air channels between them and the wingtip springs and additional springs performing a downward rolling motion each time the wing extends.

[0007] GB 270 926 A discloses a flying machine with two flapping wings, powered by an engine and curved at the front and rear near the shoulder. The wings are relatively stiff at the front and flexible at the rear, and each consists of a covered frame formed by a strong front rib tapering towards the tip, rearward-facing ribs, and lateral ribs.

[0008] The object of the invention is to provide a wing arrangement with improved aerodynamic efficiency.

[0009] This object is achieved for a wing arrangement of the type mentioned at the outset with the features of claim 1. For this purpose, the wing arrangement comprises a strut arrangement which comprises a load-bearing strut and a plurality of support struts each aligned at an angular interval between 30 degrees and 90 degrees with respect to the load-bearing strut, wherein at least some of the support struts have a front section, an adjacent connecting section and an adjacent rear section, and wherein each of the support struts is fixed to the load-bearing strut by means of the connecting section, as well as with a group of planking parts which are made of an elastic and dimensionally stable film material and which are connected to the strut arrangement.

[0010] The advantageous functionality of the wing assembly is based on the fact that the support struts are designed for a continuous flow of force between the front section, the connecting section, and the rear section, and that the support strut acts as a pivot bearing for each support strut. This ensures that, during the intended use of the wing assembly, deformation-related relative movements of the rear section relative to the support strut caused by aerodynamic forces always lead to corresponding relative movements of the front section relative to the support strut.

[0011] Purely by way of example, the support struts can be made of a fiber-reinforced plastic material to achieve a favorable compromise regarding weight and stability. For example, the fibers provided for reinforcement are embodied as natural fibers, glass fibers, Kevlar fibers, carbon fibers, or a fiber mixture thereof. Purely by way of example, the fibers provided for reinforcement are in the form of a woven, knitted, nonwoven, or knitted fabric, which is formed into the respective support strut using a curable binder material, in particular synthetic resin.

[0012] For example, the support strut is a carbon-fiber-reinforced round bar with a circular cross-section, which, during intended use of the wing assembly, is exclusively elastically deformed by the action of aerodynamic forces. It is preferably provided that, during intended use of the wing assembly in a flapping-wing aircraft, the support strut is deformed at least in sections close to the boundary between elastic and plastic deformation. This achieves a beneficial deformation of the wing assembly during an up-and-down movement that bears a strong resemblance to the flapping of a bird's wing.

[0013] It is particularly important that the support strut is secured to the load-bearing strut by the connecting section, with the load-bearing strut being oriented at least substantially transversely to the flight direction of the flapping-wing aircraft equipped with the wing assembly during intended use of the wing assembly. Accordingly, the up-and-down movements of the wing assembly, due to the resulting aerodynamic forces, lead to forces acting essentially vertically on the support struts. These forces result in torque being transmitted from the respective support strut to the load-bearing strut, whereby it can be assumed that a torque transmitted from the front section to the load-bearing strut is opposite to a torque transmitted from the rear section.In practice, in particular, a rocking movement of the respective front sections takes place relative to the respective rear section, with the support strut forming the rocker axis.

[0014] The purpose of the skinning components is to ensure the air displacement required to generate lift and / or propulsion during movement of the wing assembly by a suitably designed propulsion device of a flapping-wing aircraft. Purely by way of example, the skinning components are designed in different geometric configurations and connected to the strut assembly in such a way that, for example, during an upstroke movement of the wing assembly, the air displacement is as small as possible, while during a downstroke movement of the wing assembly, the air displacement is as great as possible, particularly in the vertical downward direction to ensure lift.The planking parts are made of a foil material which is selected with regard to its thickness and elasticity in such a way that, on the one hand, it can carry out an evasive movement by elastic deformation during the impact movement in order to enable the desired low displacement of air and, on the other hand, ensures the desired displacement of air during the impact movement by means of the support provided on the strut arrangement.

[0015] Advantageous further developments of the invention are the subject of the subclaims.

[0016] It is expedient if the support strut extends along a straight line and / or if at least one of the support struts extends along a straight line. When using rectilinear support struts and / or a rectilinear support strut, inexpensive semi-finished products such as round bars made of fiber-reinforced plastic can be used, thereby enabling cost-effective production of the strut arrangement. Furthermore, rectilinear support struts or a rectilinear support strut enable the use of identical parts, which likewise leads to low manufacturing costs. Furthermore, deformation behavior for a wing arrangement with support struts or a support strut designed in this way can be advantageously provided for and, if necessary, simulated.

[0017] Preferably, an end region of the front section spaced from the connecting section is connected to an arcuate edge strut extending between the end regions of the support struts of the strut assembly arranged at a maximum distance. The purpose of the edge strut, in conjunction with the front sections of the support struts, is to ensure a stable leading edge for the wing assembly in order to ensure advantageous airflow to the wing assembly when used in a flapping-wing aircraft and thus also a high aerodynamic efficiency for the wing assembly.

[0018] In a further development of the invention, the length of the rear section of the support strut is at least twice, preferably at least three times, the maximum distance between the support strut and the edge strut. Such a design of the support strut ensures that deformations of the wing assembly, such as those that can occur during the intended use of the wing assembly for a flapping-wing aircraft, occur essentially at the rear part of the wing assembly determined by the rear sections, while the advantage of the wing assembly determined by the front sections and the edge strut, in contrast, experiences significantly less deformation.

[0019] In a further embodiment of the invention, the connecting sections are connected in a rotationally fixed manner to the support strut, which is particularly designed to be torsionally elastic. The rotationally fixed coupling of the connecting sections to the support strut prevents excessive rocking motion of the support struts during the intended use of the wing assembly, which could occur, for example, if the connecting sections were connected to the support strut in a rotationally movable manner.In order to nevertheless ensure the desired interaction between a deflection of the rear section and a corresponding deflection of the front section, it can be provided that the support strut is dimensioned in such a way that, during the intended use of the wing arrangement, it undergoes an elastic torsional deformation due to a resulting torque which results from the torques introduced by the respective rear section and the associated front section and that this torsional deformation enables a pivoting movement of the support strut about the support strut, with which an advantageous aerodynamic behavior of the wing arrangement is ensured.

[0020] It is advantageous if adjacent support struts form an angle between 0 degrees and 25 degrees with each other. This ensures a favorable distribution of the support struts over the entire surface of the strut arrangement.

[0021] It is expedient if a front surface area, which, starting from the support strut, spans the front sections of the support struts, is provided with a front skin part belonging to the group of skin parts, which is attached to the support strut and the front sections. The front skin part should always rest against the strut assembly, regardless of the movement state of the wing assembly, in order to always ensure a favorable airflow to the areas of the wing assembly formed by the rear sections and the associated skin parts.

[0022] Preferably, it is provided that, starting from the support strut between adjacently arranged rear sections, a rear planking part belonging to the group of planking parts extends along the rear section of one of the support struts, which is fixed to the rear section by a fastening region and which, with a free end region, covers the rear section of the adjacent support strut or a projection fixed to the rear section of the adjacent support strut and belonging to another rear planking part. The rear planking part has the task of implementing a variable air resistance depending on a state of movement of the wing arrangement. This can ensure that the wing arrangement displaces a smaller amount of air during an upstroke movement due to lower air resistance than during a downstroke movement, where the wing arrangement can displace a larger amount of air due to higher air resistance.The rear panel is designed with a geometry similar to a bird's feather. The quill of the bird's feather is replicated by the support strut, which, unlike a typical bird's feather, provides edge support.

[0023] The invention is explained in more detail below with reference to the accompanying drawings. Herein: Fig. 1 is a plan view of a strut arrangement of a wing arrangement, and Fig. 2 a plan view of a wing arrangement showing the strut arrangement according to the Fig. 1 and paneling parts.

[0024] One in the Fig. The strut arrangement 10 shown in Figure 1 serves as a support structure for a Fig. 2, which is designed for use in a flapping-wing aircraft, not shown, in particular an ornithopter.

[0025] In the strut arrangement 10 according to the Fig. 1, it is provided that a support strut 11 is aligned transversely to a pivot axis 12, wherein the pivot axis 12 can be, for example, a pivot axis of a coupling device as described in the published patent application DE 10 2013 004 188 A1.

[0026] The strut arrangement 10 comprises, purely by way of example, a total of eleven support struts 15 to 25, which are aligned, for example, in an angular interval of 45 degrees to 90 degrees relative to the support strut 11. For the following description of the strut arrangement 10 and the Fig. 2, it is assumed that the supporting strut 11 and the support struts 15 to 25 are parallel to the plane of the Fig. 1 and Fig. 2 are aligned. When the wing arrangement 1 is used as intended, an elastic deformation of the individual support struts 15 to 25 can occur due to the effect of flow forces which can be caused by oscillating pivoting movements of the wing arrangement 1 about the pivot axis 12 in an air atmosphere, which can manifest itself in a curvature of the respective support strut 15 to 25.

[0027] The support struts 16 to 24 each have a front section 36 to 44, which, as shown in the Fig. 1 and Fig. 2 extends to the left of the support strut 11. Furthermore, the support struts 15 to 25 each have a rear section 45 to 55, which, according to the illustrations of the Fig. 1 and Fig. 2 extends to the right of the support strut 11. Furthermore, each of the support struts 15 to 25 is connected to the support strut 11 in a rotationally fixed manner by a connecting section 65 to 75.

[0028] Furthermore, it is provided that the support strut 25, adjacent to the rear section 55, merges, purely by way of example, into an arcuately curved edge strut 26, which extends to the connecting region 65 of the support strut 15. In this case, unspecified end regions of the support struts 16 to 24 facing away from the respective rear sections 46 to 54 are connected to the edge strut 26.

[0029] For example, it is provided that a minimum length 60 of the support struts 15 to 25 corresponds to a multiple of a maximum distance 27 between the support strut 11 and the edge strut 26.

[0030] Purely by way of example, it is intended that the support struts 15 to 20 are aligned parallel to each other, while the support struts 21 to 25 are each aligned at an acute angle to each other.

[0031] As the representation of the Fig. 1 and Fig. 2, the supporting strut 11 and the support struts 15 to 25 are each designed to be straight and can therefore be easily manufactured from round bars, for example from fiber-reinforced plastic bars.

[0032] By way of example, it is provided that a free end region 14 of the support strut 11 is designed for coupling with a joint part (not shown) of the aforementioned coupling device, wherein for a stable connection of the wing arrangement with the joint part (not shown) a coupling strut 28 is additionally provided, which is aligned at an acute angle to the support strut 11 and is connected at each end to the support strut 11 and to an edge strut 29.

[0033] As the representation of the Fig. 1 and Fig. 2, a cross-section of the support strut 11 is selected to be larger than a cross-section of the support struts 15 to 25 as well as the coupling strut 28 and the edge strut 29. This ensures that the forces occurring during a pivoting movement of the wing arrangement 1 about the pivot axis 12, which are introduced via the support strut 11, do not lead to an undesired bending deformation of the support strut 11. Preferably, a profiling of the support strut 11 (not shown in detail) is circular in a cross-sectional plane (not shown), which is oriented transversely to a longitudinal axis 30 of the support strut 11. With a suitable selection of material and dimensioning of the support strut 11, this enables torsional elasticity for the support strut 11, which enables a certain pivoting movement of the individual support struts 15 to 25 when pivoting about the pivot axis 12.

[0034] Due to the one-piece design of the support struts 16 to 24 and the design of the length ratios for the front sections 36 to 44 and the associated rear sections 46 to 54 of the support struts 16 to 24, in conjunction with the torsional elasticity of the support strut 11, it can be achieved that the forces acting on the rear sections 46 to 54 during a downstroke movement of the wing arrangement 1, on the one hand, lead to an elastic deformation of the respective rear sections 46 to 54 and, on the other hand, entail a torque introduction to the support strut 11. Due to this torque introduction, the support strut 11 executes a versioning movement about its longitudinal axis 30, which causes a change in the spatial orientation of the front sections 36 to 44 and the associated edge strut 26.With suitable coordination of the elastic deformation behavior for the rear sections 46 to 54 and the torsional elasticity of the support strut 11, an advantageous overall deformation for the wing arrangement 1 can be achieved when used in a flapping wing aircraft (not shown).

[0035] In the presentation of the Fig. 2 shows a complete wing arrangement 1, which, in addition to the one shown in Fig. 1, the strut arrangement 10 also comprises planking parts 65 to 76, which are made of an elastic and dimensionally stable foil material and which are connected to the strut arrangement 10. In the illustration of the Fig. In Figure 2, the planking parts 65 to 75 are shown in an undeformed state, which they assume, for example, in a resting state of the wing assembly 1. In this case, the planking parts 65 to 75 are at least substantially flat.

[0036] Preferably, at least the planking parts 65 to 75, also referred to as rear planking parts, are made of a plastic material which, on the one hand, has sufficient elasticity during intended use of the wing arrangement 1 to ensure the passage of air through the wing arrangement 1 during an upstroke movement of the wing arrangement 1 through elastic deformation of the individual planking parts 65 to 75. On the other hand, the plastic material of the planking parts 65 to 75 should also be sufficiently dimensionally stable to enable maximum displacement of air during a downstroke movement of the wing arrangement 1, whereby, accordingly, air should be prevented from passing through the wing arrangement 1 during the downstroke movement.

[0037] The attachment of the planking parts 65 to 75 is explained using the planking part 74 as an example, whereby the following description is at least essentially also valid for the other planking parts 65 to 73 and 75.

[0038] As can be seen from the presentation of the Fig.2, the planking part 74 covers an area that extends between the support strut 23 and the support strut 24. The planking part 74 is cut purely by way of example in such a way that it has an outer edge 80 that is aligned parallel to the support strut 24 and spaced from the support strut 24, and that it has an inner edge 81 that is aligned parallel to the support strut 23 and spaced from the support strut 23. Furthermore, the planking part 74 has a front edge 82 that is aligned purely by way of example parallel to the support strut 11, which is arranged, for example, in the region of the rear section 54 and not in the region of the front section 44 adjacent to the support strut 11. A rear edge 83 of the planking part 74 is rounded purely by way of example and extends between the support strut 24 and the support strut 23.

[0039] The planking part 74 is connected to the support strut 24 in a manner not shown in detail, for example by gluing. An inner edge 80 of the planking part 74 is arranged parallel and adjacent to the support strut 23, thus creating a strip-shaped projection 84 of the planking part 74 in the direction of the inwardly adjacent support strut 23. An outer edge 81 of the planking part 74 is aligned parallel and adjacent to the support strut 24, thus creating a projection 84 of the planking part 74 in the direction of the outwardly adjacent support strut 25.

[0040] The planking parts 65 to 75 are arranged in a scale-like manner like roof shingles, overlapping one another, wherein when viewed from an upper side of the wing arrangement 1, the planking part 65 to 74 which is arranged further inwards, i.e. closer to the pivot axis 12, is arranged above the adjacent planking part 66 to 75 which is arranged further outwards.

[0041] During a dynamic movement of the wing arrangement 1, which can be described as a sequence of an upstroke movement of the wing arrangement 1 about the pivot axis 12 and an opposite downstroke movement for the wing arrangement 1 about the pivot axis, elastic deformation of the planking parts 65 to 75 occurs during the upstroke movement, in which the respective projection, for example the projection 84, moves downwards away from the respective nearest support struts, for example the support strut 23.

[0042] This elastic deformation, which manifests itself as a curvature of the planking part 74 fixed to the support strut 24 during the impact movement, is intended to ensure the lowest possible air displacement, which also applies in the same way to the other planking parts 65 to 73 and 75.

[0043] During the subsequent downstroke movement, however, the planking part 74 should rest as tightly as possible against the adjacent planking part 73, for which purpose the projection 84 serves, which rests on the underside of the planking part 73 in the area of ​​the support strut 23. This ensures that the planking part 84 achieves the greatest possible air displacement during the downstroke movement, which also applies to the other planking parts 65 to 73 and 75.

[0044] The front sections 36 to 44 are covered by a front skin part 76 which is connected, in particular glued, to all front sections 36 to 44 and which does not experience any significant elastic deformation during the up and down movements of the wing arrangement.

Claims

[1] Wing arrangement for use in a flapping-wing aircraft, with a strut arrangement (10) which comprises a support strut (11) and a plurality of support struts (15 to 25) each aligned at an angular interval between 30 degrees and 90 degrees with respect to the support strut (11), wherein at least some of the support struts (16 to 24) have a front section (36 to 44), an adjacent connecting section (95 to 105) and an adjacent rear section (45 to 55), and wherein each of the support struts (15 to 25) is fixed to the support strut (11) by means of the connecting section (95 to 105), and with a group of skin parts (65 to 75) which are made of an elastic and dimensionally stable film material and which are connected to the strut arrangement (10). [2] Wing arrangement according to claim 1, characterized bythat the support strut (11) extends along a straight line and / or that at least one of the support struts (15 to 25) extends along a straight line. [3] Wing arrangement according to claim 1 or 2, characterized by that an end region of the front section (36 to 44) spaced from the connecting section (95 to 105) is connected to an arc-shaped edge strut (26) which extends between the end regions of support struts (15, 25) of the strut arrangement (10) arranged at a maximum distance. [4] Wing arrangement according to one of the preceding claims, characterized by that a length (60) of the rear section (45 to 55) of the support strut (15 to 25) is at least 2 times, preferably at least 3 times, a maximum distance (27) between the support strut (11) and the edge strut (26). [5] Wing arrangement according to one of the preceding claims, characterized bythat the connecting sections (95 to 105) are connected in a rotationally fixed manner to the support strut (11), which is in particular designed to be torsionally elastic. [6] Wing arrangement according to one of the preceding claims, characterized by that adjacently arranged support struts (15 to 25) enclose an angle between 0 degrees and 25 degrees with each other. [7] Wing arrangement according to one of the preceding claims, characterized by that a front surface area which, starting from the support strut, spans the front sections of the support struts, is provided with a front planking part (76) belonging to the group of planking parts (65 to 76) which is fixed to the support strut (11) and to the front sections (36 to 44). [8] Wing arrangement according to one of the preceding claims, characterized bythat starting from the support strut (11) between adjacently arranged rear sections (45 to 55), a rear planking part (65 to 75) belonging to the group of planking parts (65 to 76) extends along the rear section (45 to 55) of one of the support struts (15 to 25), which is fixed to the rear section (45 to 55) with a fastening region and which, with a free end region, covers the rear section (45 to 55) of the adjacent support strut (15 to 25) or a projection (85) belonging to a further rear planking part (65 to 75) which is fixed to the rear section (45 to 55) of the adjacent support strut (15 to 25).

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