Aerodynamic hollow chamber structures

Abstract

The invention relates to three-dimensional aerodynamic assemblies and structures, in particular in the form of wings and airfoil made of shapeable lightweight materials, which, due their special novel design as three-dimensional, grid-type (1, 2) and hollow chamber (6) containing items have a high flexural and torsional rigidity with reduced material requirements.

Description

[0001] Aerodynamic hollow chamber structures

[0002] Subject of the invention

[0003] The invention relates to three-dimensional aerodynamic arrangements and structures made of formable lightweight materials, which, due to their special novel three-dimensional, lattice-structure-like design with hollow chambers, have a high bending and torsional stiffness while at the same time minimizing material expenditure.

[0004] The invention relates in particular to such arrangements and devices which are permanently exposed to significant flow forces, for example wings and airfoils, tail units and flaps as well as fuselages of aircraft of any kind, and among these also in particular wings for airborne wind turbines, but also rotor blades of aircraft engines, drones or wind turbines, or sails for watercraft of any kind.

[0005] State of the art and task of the invention

[0006] A wing is subjected to aerodynamic, mechanical, and dynamic forces that subject the wing to bending, torsion, and local buckling and buckling. For a wing to maintain its aerodynamic and structural properties over the required operating range and service life, it must be sufficiently rigid in bending and torsion, robust against mechanical impacts, and fatigue-resistant under changing loads.

[0007] Rigid or semi-rigid wings of airborne wind turbines are high-lift wings with a high aspect ratio (ratio of wingspan to mean chord), as used in some state-of-the-art motorized aircraft, but especially in gliders, human-powered aircraft, solar-powered aircraft, and reconnaissance and combat drones. A wing with a high aspect ratio is an extremely slender structure that is flexible and capable of torsion.

[0008] The flight behavior of the majority of manned or unmanned aircraft or flying devices is characterized by relatively short takeoff and landing phases, sometimes with very high structural loads (maximum engine power during takeoff and landing), followed by longer, smooth climb and descent phases and comparatively long phases of straight flight at a largely constant speed and constant altitude at high altitudes, with smooth turns for course correction. In this flight condition, the wings usually experience only moderate loads. Load peaks during flight arise primarily from passing through turbulent air currents. An aircraft wing, such as that of a conventional commercial aircraft, absorbs the loads from the turbulent air flow through its predefined elasticity by bending. The wing also twists in the process.In addition to reducing the aircraft's structural load, this also results in greater comfort for crew and passengers, as well as gentler transport. This behavior changes the aerodynamic properties of the wing and is known as aeroelasticity.

[0009] Airborne wind turbines are generally tethered aircraft or kites. The tethering concept of an airborne wind turbine in some state-of-the-art systems involves a three-line arrangement, with one line attached to the nose of the wing as a holding line and two others attached to the wing on the left and right near the wing tips as left and right control lines. Due to this arrangement, the forces acting on the wing differ from those of aircraft. In the three-line configuration, for example, the arrangement of the three lines introduces additional torsional moments into the wing structure. By distributing the loads across three lines, the bending moments are distributed across the wingspan differently than, for example, in an aircraft.

[0010] The flight behavior of such airborne wind turbines with rotating takeoff and landing masts and figure-eight flight during the harvest phase also differs in significant respects from that of the aforementioned aircraft. Regardless of the system design, airborne wind turbines perform very few takeoffs and landings; these essentially represent an unwanted interruption to regular operations. During takeoff and landing, using a rotating mast, the loads on the wing are comparatively low, and the landing impact originates from the leading edge of the wing. Normal operation, on the other hand, is characterized by highly dynamic flight with frequent and rapid changes of direction with tight turn radii, combined with rapid and recurving alternations of acceleration and deceleration, up to and including almost complete unloading of the wing during recovery.The high number of cycles in harvesting operation of airborne wind turbines, with the change from maximum load to complete unloading, places very high demands on the robustness / fatigue strength of the blade structure, as does continuous flight at low altitude in weather with a comparatively higher probability of bird and / or hail strikes or abrasion by particles (e.g. sand) over the course of the blade's service life. At the same time, figure-eight flight, with the changing accelerations and tight turn radii described, places particular demands on the blade weight. The highest yield is achieved in figure-eight flight on a long straight line, on which the blade is accelerated to operating speed. Shortly before the turning turn, the blade is braked and the turning flight initiated. When exiting the turn, the blade is accelerated again.For high yield, the speed delta between the highest and lowest flight speeds should be as small as possible, and the period of slow turns and positive and negative acceleration phases should be kept as short as possible. In addition to the wing geometry (span), the structural weight of the wing and its distribution are crucial for the performance of the overall system. An increase in wing weight increases the system's inertia and leads to a longer turn, which is unfavorable for power production.

[0011] Numerous wing designs are known in the state of the art, which have also been used for airborne wind turbine wings, including various designs and variants of the ribbed wing, sandwich wing, or monocoque wing. However, in terms of their maximum stiffness and / or weight, these designs are not optimal for use in airborne wind turbines or other applications where high stiffness and low weight are essential.

[0012] The task was therefore to provide an aerodynamic arrangement or structure for various applications, in particular in the form of a wing, which no longer has the disadvantages of the previously known solutions and at the same time requires a relatively low use of materials.

[0013] This object has been achieved by the arrangement or structure as described below and in the claims.

[0014] Overview / Summary of the invention:

[0015] The subject of the invention is an aerodynamically effective support structure based on solid but formable lightweight materials, in particular in the form of an arrangement of two correspondingly curved grid shells which are joined together to form a solid shell, in which the grid webs of opposite grid openings are designed as hollow chambers with three-dimensional holes or hole-like openings penetrating them, so that a very torsionally and flexurally rigid three-dimensional structure is created with minimized material expenditure.

[0016] In detail, the invention relates to a three-dimensional, aerodynamically effective, flexurally and torsionally rigid support structure (S) having a predetermined profile (P) and based on solid but malleable lightweight materials in the form of an arrangement comprising a first lattice half-shell (1) and a second lattice half-shell (2) arranged opposite one another, which are preferably arranged in a convex-concave manner to one another and together form a full lattice shell (V), wherein each lattice shell consists of one or more lattice openings (L)(L') of a predetermined shape and size, which are formed by lattice webs (G)(G') surrounding them and are arranged opposite one another. In this case, the lattice webs (G)(G') orthe edges (4)(4') of at least one grid shell (1)(2)) have material indentations or material projections (5)(5') which are aligned one above the other and to one another and are positively connected to one another or directly to the edges of the grid webs of the opposite grid opening (L)(L'). This creates a three-dimensional structure consisting of one or more hollow chambers (3)(3') which are completely enclosed by material and surrounded by an aerodynamic outer surface and which are penetrated by one or more three-dimensional holes (6) which correspond in shape and size to the grid openings and are formed by the indentations or projections. The length of the connections between the two grid half-shells created by the indentations thus determines the distance between the two grid shells at one of the respective connection points.The hollow chambers (3)(3') and holes (6) as a whole form a self-contained rigid support structure (S) according to their number, shape and size.

[0017] Viewed differently, the invention also relates to a three-dimensional, aerodynamically effective, flexurally and torsionally rigid structure in the form of a solid full shell (V) made of lightweight materials for an aircraft or for rotors, comprising at least one first upper solid half-shell (1) and at least one second lower solid half-shell (2) of the same shape, curvature, and size, which are preferably arranged in a convex-concave manner relative to one another and are positively connected to one another, wherein a three-dimensional support matrix with a predetermined profile is provided inside the full shell at specific points or in specific regions at a specific distance between the half-shells. According to the invention, this is formed in that one or more openings (6) of a selected shape and size arranged one above the other are provided in each of the two solid half-shells (1)(2) provided with an outer cover.The openings (6) are formed by material indentations (5)(5') of the lattice openings of the first lattice half-shell (1) with edges (4)(4') or material indentations of opposite lattice openings of the second lattice shell (2). This creates closed hollow chambers (3)(3') with a corresponding shape, whereby the material, number, and shape of the hollow chambers and the resulting hole-like openings determine the rigidity of the half-shells and thus of the full shell within a specific range.

[0018] In general, the lattice structures described above for half-shells are also applicable according to the invention to a correspondingly equipped full shell (V), which is manufactured from a single piece without additional connecting elements. Thus, the following embodiments relating to lattice half-shells are also applicable according to the invention to corresponding lattice full shells and are therefore not described explicitly.

[0019] In a first embodiment, the invention relates to an aerodynamically effective, flexurally and torsionally rigid support structure (S) comprising a first upper curved lattice half-shell (1) and a second lower, oppositely arranged, curved lattice half-shell (2), which together form a full lattice shell (V) with corresponding lattice openings (L)(L'), which preferably has a convexly curved upper surface and a concavely curved lower surface, or vice versa. One or more edges or margins (4)(4') of the original lattice webs (G)(G') of the lattice half-shells have one or more indentations or projections (5)(5') which are bent and aligned in such a way that they are positively connected to corresponding edges or margins or indentations or projections of the opposite lattice half-shell.This creates one or more hollow chambers (3)(3') completely enclosed by material of the lightweight construction material, created from the original lattice webs (G)(G') of both shells, which are separated from each other by three-dimensional holes or openings (6) formed by the side edges of the hollow chambers and corresponding to the shape of the original lattice openings.

[0020] Regardless of whether one starts from half-shells with a lattice structure or from compact half-shells, according to the invention one ultimately obtains a full shell which has continuous three-dimensional holes (6), wherein the shape and dimensions of the lattice shells result in a defined distance between the two lattice shells and thus define a desired profile (P).

[0021] Likewise, the selected number, shape, and size of the hollow chambers and holes or openings, or the number and shape of the interconnected hollow chambers, can influence the desired rigidity of the entire support structure according to the invention or only in specific areas where, depending on the application, a greater external force is to be expected. The three-dimensional holes (6) between the two lattice half-shells (1)(2) or in the lattice full shell (V) can have an at least partially rounded contour and / or an at least partially curved side surface, thereby determining the shape of the hollow chambers (3)(3').

[0022] The hollow chambers (3)(3') as a whole have an outer surface of 5 - 80%, preferably 10 - 80% of the surface of the lattice half-shells (1)(2) or the lattice full shell (V), or a volume of 5 - 90%, preferably 10 - 90% of the volume of the lattice full shell (V).

[0023] The holes or openings (6) as a whole have an outer surface of 20 - 95%, preferably 20 - 90% of the surface of the grid half-shells (1)(2) or the grid full shell (V), or a volume of 10 - 95%, preferably 10 - 90% of the volume of the grid full shell (V).

[0024] If multiple hollow chambers are present, they can be interconnected by channels or narrow, appropriately shaped connecting cavities. As a whole, they can have a thin, ribbon-like shape adapted to the given profile of the structure. Ultimately, the number, shape, and arrangement of the hollow chambers and perforated structures depend on the desired stiffness in relation to the weight of the supporting structure.

[0025] The hollow chambers (3)(3') and the three-dimensional holes (6) can be arranged in particularly large numbers in those areas of the lattice half-shells (1)(2) or the lattice full shell (V) which are exposed to a significant external force.

[0026] In a further embodiment of the invention, the hollow chambers (3)(3') may have in their interior further narrow, optionally branched and interconnected hollow space structures enclosed by the lightweight material, which are arranged and connected to the outer wall of the hollow chambers in such a way that they additionally contribute to the stabilization of the support structure, preferably at positions of significant external force action.

[0027] In another embodiment of the invention, the originally lattice-shaped or solid half-shells of the support structure are designed as double half-shells (1)(T), (2)(2') or even multiple half-shells, each with essentially the same curvature and a predetermined distance from one another, wherein each double or multiple half-shell has holes (6a) arranged one above the other between the individual lattice half-shells constructed from them, which are positively connected to one another by corresponding indentations. This creates a three-dimensional shell structure provided with holes, which is thereby additionally stiffened. Independently of this, the support structure also has the continuous hole structures described above and below, which are responsible for the actual high rigidity of the full shell with minimized material usage according to the invention.

[0028] As already mentioned, the support structure made of lattice half-shells described above and in the claims can also be regarded as a three-dimensional, aerodynamically effective, flexurally and torsionally rigid solid full shell (V) made of lightweight materials, which comprises at least one first upper solid half-shell (1) and at least one second lower solid half-shell (2) of the same curvature and size, which are preferably arranged convexly-concave to one another and are positively connected to one another, wherein a three-dimensional support matrix with a predetermined profile (P) is provided inside the full shell (V) at certain points or in certain areas at a certain distance between the half-shells.The three-dimensional support matrix is ​​formed in that in each of the two solid half-shells (1)(2) one or more hole-like openings (6) of a selected shape and size are provided, arranged one above the other, the edges (4) of which in at least one half-shell have indentations or projections (5) which are connected to edges (4') or indentations or projections (5') of the respectively opposite openings (6) of the other half-shell in such a way that at least one closed hollow chamber (3)(3') of a corresponding shape is formed, wherein the material, number and shape of the hollow chambers and the hole-like openings formed determine the rigidity of the solid shell in a specific range.

[0029] In such a solid shell (V), the first upper half-shell (1) and the second lower half-shell (2) can each be designed as double half-shells or multiple half-shells (1)(1'), (2)(2') connected at the edges, each with the same curvature of the shells and a predetermined distance from one another, wherein each double or multiple half-shell has holes (6a) arranged one above the other between the individual solid half-shells, which are positively connected to one another by invaginations, so that the support structure is further stiffened with minimized use of material. Individual or all of the hollow chambers (3)(3') can have further narrow, if necessary, hollow chambers enclosed by the lightweight material inside them.branched and interconnected hollow space structures (3b) which are arranged and connected to the outer surface of the at least one hollow chamber in such a way that they additionally contribute to the stabilization of the support structure at positions of significant external force. In order to aerodynamically optimize the support structure according to the invention, the invention provides for it to be provided with a tightly fitting outer skin (7). This can be a membrane-like planking made of solid materials, but preferably a flexible covering, such as a film or coated or uncoated fabric. The covering or planking can cover the entire outer surface of the support structure or be provided only for the outer perforated structures. In any case, the intention is to obtain a completely closed, aerodynamically effective, tightly spanning surface corresponding to the profile of the half-shells or the full shell.

[0030] As already mentioned, the support structure (S) according to the invention can be used for many applications where optimal aerodynamics, low material weight and high stability are required.

[0031] This is particularly the case with all types of aircraft, such as a wing, a support surface, a tail unit, a flap, a rotor blade, a propeller, an aircraft fuselage or a sail.

[0032] The subject of the invention is therefore in particular a wing or a wing of a flight-capable device with an upper and a lower side, preferably made of a lightweight material, for example a carbon fiber reinforced resin and a partial or complete planking or covering (7), preferably with a fabric or a film, which is constructed from one or more hollow chambers (3)(3') which are separated from one another by hole-like openings (6) between the upper and lower sides and / or connecting channels.

[0033] The leading edge or nose (N) and, if applicable, the trailing edge or trailing edge (E) of the wing or airfoil are formed by or replaced by at least one hollow chamber. The hollow chamber(s) of the leading edge and the hollow chamber(s) of the trailing edge can be connected by at least one narrow, correspondingly shaped connecting cavity or connecting channel, which separates at least two three-dimensional openings or holes (6).

[0034] According to the invention, the hollow chambers, openings and connecting channels are designed in their shape and thickness according to the shape of a given profile.

[0035] Preferably, the volume of the trailing edge hollow chamber(s) forming the trailing edge is less than 10% of the volume of the leading edge hollow chamber(s) and the connecting channels together, and the total of the openings or three-dimensional holes present on the wing occupy 40-80% of the area of ​​the upper or lower surface of the wing or 40-80% of the volume of the wing or the wing surface.

[0036] According to the invention, such a wing or such a wing surface can also have partitions or ribs (R) running through the cross-section, which divide the wing or wing surface into individual segments or compartments, which can be plugged together, glued together, or otherwise connected. The variable support structure for a wing according to the invention, which can be designed according to the desired applications and the acting forces, generally does not require the otherwise conventional spars for stiffening.

[0037] In a specific embodiment of the invention, the connection of individual adjacent segments or compartments can be achieved by overlapping terminal ribs (R) of two adjacent segments (S1)(S2) to be connected, whereby the terminal rib (R) of the upper half-shell (1) of the first segment (S1) is connected to the lower half-shell (2) of the second segment (S2), and likewise the terminal rib (R) of the lower half-shell (2) of the second segment (S2) is connected to the upper half-shell (1) of the first segment (S1). Segments of a lattice full shell can also be connected to one another in a similar manner.

[0038] The wing according to the invention is ideally suited for use in airborne wind turbines.

[0039] The invention thus also relates to an airborne wind turbine, which essentially comprises a ground station, a generator, and a line system connecting the ground station to a wing suitable for curved flight. The system is guided and controlled by a release and retrieval device from the ground station. The kinetic energy generated by the wind-driven flight motion of the wing is converted into electrical energy.

[0040] The subject matter of the invention is ultimately a method for producing a wing or a wing according to the invention, wherein a correspondingly designed upper and lower lattice half-shell or a correspondingly designed upper and lower half-shell in the shape and profile of a wing or a wing are each provided as a shaped piece made of a fiber composite material, then the respective two half-shells are glued, welded or positively connected to one another by other fastening means at intended edges, corners, projections, indentations or connecting lips and finally the solid shell thus obtained, provided with holes or openings, is covered with a flexible membrane made of fabric or film plane-parallel to the shell shape, or a plane-parallel planking is provided with a rigid material.

[0041] The invention also relates to a further method for producing a wing or a wing according to the invention, in which the wing or the wing is manufactured in one piece, for example by means of 3D printing or other manufacturing methods suitable for such purposes in the prior art.

[0042] Finally, the invention also relates to a corresponding method in which individual grid segments are connected to one another via their terminal partition walls or ribs in a form-fitting manner and with increased stability, as described in more detail above and below.

[0043] The support structures according to the invention, particularly for wings, airfoils, rotor blades and propellers, have the following advantages:

[0044] - High dimensional stability (flexural / torsion-resistant),

[0045] - Robustness and durability with minimal structural weight

[0046] - Maximum reduction of joints and weak points

[0047] - Maximum reduction of different components

[0048] - Reduction in material usage

[0049] - Reduction of process steps

[0050] - Minimization of environmentally problematic production materials

[0051] - Minimizing the use of adhesive

[0052] - Simplification of the bonding process and bonding paths

[0053] - Improvement of the verifiability of the quality of bonding by avoiding undercuts

[0054] - Self-aligning joint possible

[0055] - No or only very simple assembly aids required

[0056] - Mold tools can be used as assembly aids (idea for the process: Invent)

[0057] - Simple but highly precise joining of components - Assembly in a continuous operation or work process without interruptions due to waiting times

[0058] - Minimal trimming and post-processing effort

[0059] - Very high optimization potential due to the very large parameter space due to the complex topology and small number of parts without a significant increase in complexity or number of parts.

[0060] Reference values ​​used:

[0061] (S) Supporting structure (wing, wing, etc.)

[0062] (S1)(S2) Segments of the support structure

[0063] (P) Profile of the support structure (S)

[0064] (V)(V') Grid full shell or solid full shell

[0065] (G) Grid bridges

[0066] (L)(L') Grille openings

[0067] (N) Leading edge / nose wing / wing

[0068] (E) Trailing edge of wing

[0069] (1) upper lattice half-shell or upper solid half-shell

[0070] (1 ') upper lattice half-shell or upper solid half-shell of the same curvature as (1)

[0071] (2) lower lattice half-shell or lower solid half-shell

[0072] (2') lower lattice half-shell or lower solid half-shell of the same curvature as (2)

[0073] (3) Hollow chamber (in the front area of ​​the wing)

[0074] (3') Hollow chamber (in the rear area of ​​the wing)

[0075] (3a) Connecting cavity between (3) and (3') (wing)

[0076] (3b) additional cavity structure around the interior of (3) (3')

[0077] (4) Edge / edge grid bar (G) or holes (6)

[0078] (5) Invagination / protrusion of the holes (6) of the upper half shell

[0079] (5') Invagination / protrusion of the holes (6) of the lower half shell

[0080] (6) three-dimensional hole or hole-like breakthrough through the entire support structure

[0081] (6a) three-dimensional hole or hole-like breakthrough through two adjacent

[0082] (Lattice) half-shells of the same curvature of a double or multiple half-shell

[0083] (7) Membrane, foil, planking

[0084] (Ü, Ü') Overlaps upper with lower grid shell

[0085] (Si, Si') Beads in the area of ​​overlaps

[0086] (Za, Za') fixing pin

[0087] (LW) tail unit of a wing

[0088] (K) Edge

[0089] (R) Rib of a wing Description of the images:

[0090] Fig. 1 shows a perspective view of a complete swept-back wing according to the invention, with side stabilizers, winglets, and covering (only parts shown). The shape and size of the openings (6), and thus also the shape of the hollow structures, vary. In the central segment, often subject to the greatest stress, the hollow chambers take up the most space. The openings here are triangular, as these provide greater rigidity. In terms of number and arrangement, more holes (6) are provided in the outer regions of the wing than in the central regions.

[0091] Fig. 2 shows the grid shell wing of Fig. 1, which is cut open in the area of ​​a segment (S).

[0092] Fig. 3 shows an exploded view of the gridshell wing of Fig. 1.

[0093] Fig. 4 (A) shows a perspective view of a segment part of a wing according to the invention for an aircraft, designed as a solid shell and manufactured in one piece. The leading edge or nose (N) of the wing is formed by a positive connection of an upper grid shell (1) and a lower grid shell (2). Their convex-concave arrangement to one another results in a grid full shell (V). Both grid shells have rounded, rectangular grid openings in the shape of the profile (P) of the wing. In the example shown, the grid openings are arranged parallel and perpendicular to the leading edge. In principle, they can be aligned as desired, shaped as desired, and even have a variable number. The grid openings of the upper grid shell are advantageously arranged vertically above those of the lower grid shell and are preferably of identical size and shape. The upper and lower grid openings thus form a three-dimensional hole oran opening (6) through the support structure delimited and formed by the two grid shells. At the edges or borders (4) of the grid openings of the upper and lower grid shells, indentations or projections (5)(5') made of the grid shell material are provided, which are positively connected to one another. In the area of ​​the nose or leading edge of the wing, the indentations are, in accordance with the wing profile, significantly larger or wider at this point than in the area of ​​the trailing edge or trailing edge of the wing. This creates a large hollow chamber (3) in the front area of ​​the wing, a very small hollow chamber (3') at the trailing edge, and a cavity of varying width (3a) as a connecting part between the two connected hollow chambers (3)(3'). In this embodiment of the invention, the connecting cavities (3a) resemble the classic solid ribs, but are significantly stiffer. The dashed line is intended to represent the covering of the wing, e.g.in the form of a membrane made of foil or fabric that tightly surrounds the wing. Figure 4B shows a corresponding segment part composed of two lattice half-shells. The upper half-shell has a convex curvature, while the lower half-shell has a concave curvature. shows a cross section AA ) through the wing according to the invention of Fig.

[0094] 1-4, where (A) shows a full shell made from one piece and (B) a full shell made from two half-shells. In each case, the large hollow chamber (3) at the front

[0095] Area of ​​the wing, the small hollow chamber (3') at the rear end of the wing as well as the connecting cavity including the side walls can be seen, which are formed by the upper indentations (5) and lower indentations (5') attached to the edges (4) of the grid openings in the shape of the wing profile. iq. 6 shows a section BB through a wing according to the invention, as in

[0096] Fig. 5 shown..

[0097] Fig. 7(A) (B) shows embodiments of a gridshell wing according to the invention which is composed of segments.

[0098] Fig. 7 (A) shows how two adjacent segments are joined using the example of the double-shelled full shell according to the invention (visible on the right side of the image). In segment 2 (S2), the lower lattice half-shell (2) is guided up to the upper lattice half-shell (1) at a terminal rib (R) and structurally connected to it, for example, by bonding, creating a projection (Ü) in the area of ​​the upper half-shell. At the same time, the lower shell (2) has a bead (Si).

[0099] For segment 1 (S1), the situation is reversed: at the terminal rib, the upper shell (1) is brought down to the lower shell (2) and connected to it, also creating an overhang (Ü') in the area of ​​the lower lattice half-shell (2) and, at the same time, a bead (Si') on the upper half-shell. The respective overhangs overlap with the beads in the opposite shell, thus maintaining a uniformly smooth surface at the counter-shell. The overhangs offer the option of bolting the wing segments together via the wing shell. For the structural connection of the segments, tenons (Za), (Za') can be formed from the flank of the shell, which interlock and can transmit bending forces.

[0100] Fig. 7 (B) shows a perspective view of the wing section according to Fig. 7 (A), in which the terminal ribs (R) can be seen. Fig. 8 (A)(B)(C) shows different sections (AA, BB, CC) through a special embodiment of a grid shell of a wing profile according to the invention, formed from an upper (1) and a lower (2) grid shell, each of which has a further grid shell of the same curvature (1')(2') with corresponding invaginations and hollow structures (6) (6a) (3) / 3a), which are additionally created in the spaces between the grid shells (1) and (T), or between the grid shells (2) and (2'), whereby the entire grid structure experiences particular strength with low material usage.

[0101] Fig. 9 shows a longitudinal section through a portion of a wing according to the invention, which is manufactured as a one-piece solid shell (V). Here, the connecting cavities (3a) including the side walls can be seen, which are formed by the upper indentations (5) and lower indentations (5') attached to the edges (4) of the grille openings in the shape of the wing profile.

[0102] Further details of the invention

[0103] A hollow chamber, as used in the present invention for the aerodynamic support structures according to the invention, is usually a thin-walled element whose shape or arrangement results in a cross-sectional shape that encloses a hollow space. This cross-sectional shape imparts a slender structural element, such as a wing spar, high resistance to bending, torsion, and buckling because the walls of the structural element in question are located away from the center of gravity, thus achieving a high bending section modulus. A high torsional section modulus is additionally achieved by completely enclosing the hollow space with a selected solid material.

[0104] The concept of a hollow chamber structure, in particular a hollow chamber wing, presented here is based on the assumption that, for example, in the case of a wing or a wing, an integral transition (no change of material, no joint) from the D-spar via the hollow ribs and the trailing edge, which is also designed as a hollow chamber, can achieve additional torsional stiffness compared to the pure D-spar structural principle.

[0105] It is further assumed that the hollow chamber principle will enable wing structures in which the strict functional division of the structural spar on the one hand and the shaping rib, leading edge, and trailing edge on the other can be abandoned in favor of an integral structural principle in which all elements contribute to the flexural and torsional stiffness of the wing. The underlying principle is also applicable to other aerodynamic structures, such as rotor blades, propellers, or fuselages of all types of aircraft.

[0106] In the present invention, the hollow chamber principle is applied to, or combined with, a grid shell structure. Instead of the grid webs, which according to the prior art are generally made of solid material, the invention formally uses hollow chambers of various sizes and shapes, which are preferably used at those points on the support structure according to the invention that require particular stability (torsional and flexural rigidity). The size and shape of the hollow chambers enclosed by solid material thus also determine the size, shape, and distribution of the openings or holes in the grid shells.

[0107] The support structures according to the invention can be understood in principle as a form-fitting connection of a first upper curved lattice half-shell and a second lower curved lattice half-shell, forming a full lattice shell with a convex-concave or concave-convex outer shape. Preferably, the upper lattice half-shell is convex, and the lower lattice half-shell is concave. However, the invention also encompasses correspondingly designed support structures that have a biconvex or biconcave outer shape.

[0108] In the case of the solid lattice shell, as already mentioned, the originally solid lattice webs are widened in many areas and converted into one or more hollow chambers, which are separated by or surrounded by lattice openings. The conversion into hollow chambers is achieved by providing invaginations or projections at the edges of the originally widened lattice webs on both lattice half-shells, which are bent toward each other and connected in a form-fitting manner to form a space enclosed by solid material. The invaginations or edges form the side walls of the now lattice openings and, at a specific point, define the distance between the half-shells, thus contributing to the three-dimensional profile of the structure.

[0109] In contrast to lattice half-shells, where the lattice structure determines the arrangement and shape of the hollow chambers, the solid shell made of solid material can have openings or perforations arranged in any order in the solid shell, but these are created in a similar way to the lattice shell, i.e. by appropriate material invaginations. The size of the openings as well as their surface contours can be regular or irregular. The lattice full shell or the solid full shell and thus the corresponding support structure can have openings or perforations that are circular, oval, triangular, square or polygonal in shape and can be distributed regularly, e.g. as a honeycomb structure, or irregularly across the shell. The size of the openings or perforations can increase to such an extent that the actual support matrix consists only of thin, ribbon-like cavities or channels.These can be spatially curved to form three-dimensional lattices, which in turn can enclose cavities.

[0110] According to the invention, the three-dimensional openings or perforations serve to reduce weight compared to a solid shell made of solid material, while the indentations at the hole edges or their side walls ensure the connection of the two opposing half-shells and thus serve to stiffen the shell. The number, arrangement, and placement of the openings or hollow chambers in the support structure can therefore specifically influence the weight and stability / stiffness of the structure, for example, a wing or aerofoil, which can thus be optimized for application requirements.

[0111] The outer skin provided according to the invention for the entire aerodynamic support structure in the form of a film or membrane or a planking of the support structure according to the invention also contributes significantly to the stability, which also closes the holes or openings on the shell surfaces and spans them in a plane-parallel manner.

[0112] When applied to wings or airfoils of any type of aircraft, it is irrelevant for the inventive construction principle whether the wing or wing segment is composed of one or more shell elements and / or one or more cells or webs. Furthermore, ribs and trailing edges designed as hollow chambers can be made significantly lighter than, for example, truss structures or plate elements, while maintaining the same or greater rigidity and robustness against mechanical influences. By minimizing joints as points of failure, structural weakening due to material changes, and disruption of the flow of forces, improved fatigue strength of the hollow chamber construction is achieved. The essentially constant complexity of the molding tool allows for more complex structures to enhance performance without a significant increase in expenditure or changes in production processes.The support structures according to the invention, in particular wings or airfoils, can be manufactured in various ways using conventional methods. In principle, it is possible to produce the three-dimensional profile structures of a wing in a single molded piece from moldable or castable lightweight materials, such as, for example, (carbon) fiber-reinforced plastics or resins, for example, using 3D printers.

[0113] Alternatively, it is possible to use at least two forming tools per wing segment. The segment is then composed of two half-shells, an upper and a lower half-shell.

[0114] If vertical stabilizers are required, additional shell elements must be created accordingly. Multiple shells, i.e., additional overlapping elements or compartments, are also easily conceivable. The individual compartments or segments can be plugged together using special plug-in connectors or glued together in an overlapping manner to create a complete wing without any joints or segmentation.

[0115] Bonding can be done directly or via specially designed adhesive lips. However, conventional processes, such as those used in carbon racing bike construction, can also be used to seamlessly create such hollow bodies or structures. This involves placing tubes wrapped with carbon fiber blanks into the mold. Then, under pressure, the fiber matrix is ​​pressed into the mold. This creates a single, seamless molded part.

[0116] In contrast to the classic design of a ribbed or shell wing, the production of the support structures according to the invention, particularly the blades for an airborne wind turbine, requires only a few large-format molds. This allows the proportion of machine resources to be increased relative to the proportion of personnel, thus reducing production costs.

[0117] The assembly is considerably simplified compared to the monocoque construction and the spar-rib construction, since the wing components such as spar webs and ribs are virtually integrated into the mold for stiffening.

[0118] The bonding paths are very simple, as they have no undercuts or tight angles, and are therefore ideally suited for mechanical application of the adhesive. The amount of adhesive on the segment is significantly reduced compared to a spar-and-rib design, or even a monocoque design. Post-processing, i.e., trimming the molds, is also very simple, as only a few parts require post-processing. Post-processing of the segment (removing excess adhesive) is less complex than with the spar-and-rib design. With the monocoque design, excess adhesive remains in the component. Furthermore, the trimming paths are also well suited for mechanical processing. The novel design of the support structures according to the invention, particularly of wings or airfoils, thus allows for particularly advantageous and efficient production and assembly of these structures, with great potential for very high levels of automation in production.

[0119] If the lattice-shaped wing or the lattice-shaped support structure is constructed from segments, these can also be joined together according to the invention as indicated in the description of Fig. 7B.

Claims

1. Three-dimensional aerodynamically effective, flexurally and torsionally rigid support structure (S) with a given profile (P) based on solid but malleable lightweight materials in the form of (i) an arrangement of a first curved lattice half-shell (1) and a second oppositely arranged curved lattice half-shell (2), which are arranged relative to one another in such a way that they form a lattice full shell (V) with correspondingly curved surfaces, or (ii) a lattice shell (V) having a curved surface; each consisting of one or more grid openings (L)(L') of a predetermined shape and size and grid webs (G)(G') with edges (4)(4') surrounding them, characterized in that at provided grid openings (L)(L') the grid webs (G)(G') of at least one grid shell (1)(2) or of the grid full shell (V) have material indentations or material projections (5)(5') on the edges (4)(4'), and said indentations or projections are aligned one above the other and are positively connected to one another or to the edges of the grid webs of the opposite grid opening (L)(L') in such a way that one or more hollow chambers (3)(3') are present, which are completely enclosed by material and surrounded by an aerodynamic outer surface and are formed by one or more hollow chambers (3)(3') corresponding in shape and size to the grid openings and formed by the indentations or projections,three-dimensional holes (6) are penetrated, wherein the length of the indentations or projections determine the distance between the surface of the two grid shells or the full shell at the respective connection points, and the hollow chambers (3)(3') and holes (6) as a whole form a self-contained rigid support structure (S) according to their number, shape and size.

2. Three-dimensional aerodynamic support structure according to claim 1, characterized in that the three-dimensional holes (6) between the two lattice half-shells (1)(2) or in the lattice full shell (V) have an at least partially rounded contour and / or an at least partially curved side surface, and thereby also predetermine the shape of the hollow chambers (3)(3').

3. Three-dimensional aerodynamic support structure according to claim 1 or 2, characterized in that it has a single grid opening (L) and a single hollow chamber closed by an outer surface, which is divided into at least two regions (3) and (3') which are connected to one another by narrow, correspondingly shaped connecting cavities or connecting channels (3a).

4. Three-dimensional aerodynamic support structure according to one of claims 1 - 3, characterized in that (a) the hollow chambers (3)(3') as a whole have an outer surface of 5 - 80%, preferably 10 - 80% of the surface of the grid half-shells (1)(2) or the grid full shell (V), or a volume of 5 - 90%, preferably 10 - 90% of the volume of the grid full shell (V), and / or (b) the holes (6) as a whole have an outer surface of 20 - 95%, preferably 20 - 90% of the surface of the grid half-shells (1)(2) or the grid full shell (V), or a volume of 10 - 95%, preferably 10 - 90% of the volume of the grid full shell (V).

5. Three-dimensional aerodynamic support structure according to one of claims 1 - 4, characterized in that it is divided into compartments or segments (S1)(S2) which are separated from one another by terminal fixed partition walls or ribs, wherein the compartments or segments are joined and connected in a form-fitting manner, and at least one compartment has at least one hollow chamber (3)(3') and at least one hole (6).

6. Three-dimensional aerodynamic support structure according to claim 5, characterized in that a first and second adjacent segment or compartment (S1)(S2) are connected to one another in such a way that a terminal rib or partition wall of the upper lattice half-shell (1), or of an upper region of the lattice full shell (V) of the first segment (S1), is guided to the lower lattice half-shell (2), or to a lower region of the lattice full shell of the adjacent second segment (S2), and a terminal rib or partition wall of the lower lattice half-shell (2) or of a lower region of the lattice full shell (V) of the second segment (S2) is guided to the upper lattice half-shell (1), or to an upper region of the lattice full shell (V) of the adjacent first segment (S1), forming in each case an overlapping region (Ü, Ü') and a bead (Si, Si'), in the region of which elements for firmly connecting the two segments or compartments are provided.

7. Three-dimensional aerodynamic support structure according to one of claims 1 - 6, characterized in that the hollow chambers (3)(3') and the three-dimensional holes (6) are arranged in those areas of the lattice half-shells (1)(2) or the lattice full shell (V) which are exposed to a significant external force 8. Three-dimensional aerodynamic support structure according to one of claims 1 - 7, characterized in that one or more hollow chambers (3)(3') have in their interior further narrow, optionally branched and interconnected hollow space structures enclosed by the lightweight material, which are arranged and connected to the outer surface of the at least one hollow chamber in such a way that they additionally contribute to the stabilization of the support structure at positions of significant external force action.

9. Three-dimensional aerodynamic support structure according to one of claims 1 - 8, characterized in that it is composed of two lattice half-shells (1)(2) which are suitably connected to one another.

10. Three-dimensional aerodynamic support structure according to claim 9, characterized in that (a) the first lattice half-shell (1) is connected at the edges to at least one second lattice half-shell (T) of the same curvature, arranged congruently above or below it at a predetermined distance, and forms a lattice double or multiple lattice half-shell (1)(T), and (b) the second lattice half-shell (2) is connected at the edges to a second lattice half-shell (2') of the same curvature, which is arranged congruently above or below it at a predetermined distance, and forms a double or multiple lattice half-shell (2)(2'), wherein the lattice half-shells (1)(T) enclosed by material have holes (6a) arranged one above the other, which are positively connected to one another by invaginations of the material, whereby the support structure is further stiffened with minimized use of material.

11. Three-dimensional aerodynamic support structure according to one of claims 1 - 8, characterized in that it consists of a lattice shell (V) manufactured in one piece.

12. Three-dimensional aerodynamic support structure according to claim 11, characterized in that the lattice full shell (V) is connected to a second lattice full shell (V) of the same curvature, which is arranged congruently above or below it at a predetermined distance, wherein the lattice full shells (V)(V) enclosed by material have holes (6a) arranged one above the other, which are positively connected to one another by invaginations (5a)(5a') of the material.

13. Three-dimensional aerodynamic support structure according to one of claims 1 - 12, characterized in that the joined lattice half-shells (1)(2) or the lattice full shell (V) have a concavely curved surface and an opposite convexly curved surface.

14. Three-dimensional aerodynamic support structure according to one of claims 1 - 13, characterized in that it has a complete or partial covering with a membrane made of fabric or film or a planking made of lightweight materials (7) which covers the hole(s) (6)(6a) located on the outside of the support structure, so that an outwardly completely closed, aerodynamically effective surface corresponding to the profile of the structure is present.

15. Three-dimensional aerodynamic support structure according to one of claims 1 - 14, characterized in that it is made of fiber composite material, plastic or light metal.

16. Three-dimensional aerodynamic support structure according to one of claims 1-15, characterized in that it has the shape of a wing, a support surface, a tail unit, a rotor blade, a fuselage or a control surface, a cover, a flap or a slat element of an aircraft, or a sail for a watercraft.

17. Wing or airfoil according to claim 16 with a predetermined profile (P) and a complete or partial covering with a membrane made of a fabric or a film (7) or a planking made of lightweight materials, comprising a leading edge (N) and a trailing edge (E), characterized in that (i) the leading edge (N) of the wing or the airfoil is formed by or replaced by at least one hollow chamber (3) which corresponds in thickness to the shape of the given profile, and / or (ii) the trailing edge (E) of the wing or airfoil of at least one hollow chamber (3') is formed or replaced by this, which corresponds in terms of its thickness to the shape of the given profile.

18. Airborne wind turbine, comprising a ground station, a line system which connects the ground station to a wing suitable for turning flight and is guided and controlled by an outlet and retrieval device from the ground station, and a generator which converts the kinetic energy obtained by the wind-driven flight movement of the wing into electrical energy, characterized in that it has a wing or a wing according to claim 17.

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