Aircraft With Load Reducing Wing Like Element

Abstract

An aircraft includes a fuselage, a wing attached thereto, a wing tip device attached to a wing end of the wing (2), a wing-like element having a wing root, a wing leading edge and a wing trailing edge, and a torque control device having a rotatable interface means. The torque control device is adapted for rotatably supporting the wing root of the wing-like element on the interface means about a rotational axis extending from the interface means into the wing-like element and to limit the degree of rotation depending on a torque introduced into the interface means by the wing-like element. The wing-like element is adapted to induce a rotation around the rotational axis in an air flow. The wing root is coupled with the wing tip device, the wing or the fuselage through the torque control device such that the leading edge extends into an airflow surrounding the aircraft.

Claims

1. An aircraft comprising: a fuselage; a wing attached to the fuselage; a wing tip device attached to a wing end of the wing; at least one additional wing-like element having a wing root, a wing leading edge and a wing trailing edge; and a passive torque control device having a rotatable interface, wherein the passive torque control device is adapted for rotatably supporting the wing root of the wing-like element on the interface under creation of a rotational axis extending from the interface into the wing-like element, about which rotational axis the wing-like element is rotatable, the rotational axis extending perpendicularly to a chord of the wing-like element and defined in a plane spanned up by a first inner point of the trailing edge and by a tangent at a second inner point of the leading edge, wherein the wing-like element is adapted to induce a rotation around the rotational axis in an air flow, wherein the passive torque control device is adapted to limit the degree of rotation depending on a torque introduced into the interface by the wing-like element, and wherein the wing root of the at least one wing-like element is coupled with at least one of the wing tip device, the wing and the fuselage through the passive torque control device such that the leading edge extends into an airflow surrounding the aircraft.

2. The aircraft of claim 1, wherein the rotational axis extends essentially perpendicular to the wing root of the wing-like element.

3. The aircraft of claim 2, wherein the rotational axis extends through a point in a distance to an aerodynamic center of the wing-like element proximal to the leading edge.

4. The aircraft of claim 3, wherein the distance to the aerodynamic center is at least 5% of a chord of the wing root of the wing-like element.

5. The aircraft of claim 1, wherein the passive torque control device comprises at least one spring coupled with the rotatable interface and a structurally fixed point of the aircraft in a manner that a rotation of the rotatable interface leads to compression or expansion of the at least one spring.

6. The aircraft of claim 5, wherein the passive torque control device further comprises a damping unit in a parallel connection to the at least one spring.

7. The aircraft of claim 1, wherein the passive torque control device comprises an actuator mechanically coupled with the rotatable interface and a control unit, and wherein the control unit is connected to the actuator and is adapted for rotating the rotatable interface depending on a physical parameter indicative of the torque acting upon the rotatable interface.

8. The aircraft of claim 1, wherein the at least one wing-like element is arranged in a transition region of the wing tip device.

9. The aircraft of claim 8, wherein the wing comprises two wing halves, wherein each wing half comprises a wing tip device, and wherein both wing tip devices comprise at least one wing-like element.

10. The aircraft of claim 8, wherein the wing-like element extends over the wing tip device in a spanwise direction at least during a cruise flight condition.

11. The aircraft of claim 10, wherein the wing-like element does not extend over the wing tip device in a spanwise direction when on ground.

12. The aircraft of claim 8, wherein the rotational axis of the at least one wing-like element extends at an angle of at least 10° to a vertical and of at least 10° to a horizontal plane of the aircraft.

13. The aircraft of claim 1, wherein the rotational axis of the at least one wing-like element extends perpendicular to a longitudinal axis of the aircraft.

14. The aircraft of claim 1, comprising a wing-like element at a forward portion of the fuselage forward of the wing.

15. The aircraft of claim 1, wherein the rotational axis defines a predetermined angle with a lateral axis of the aircraft in a range of 100° to 170°.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other characteristics, advantages and potential applications of the present invention result from the following description of the exemplary embodiments illustrated in the figures. In this respect, all described and/or graphically illustrated characteristics also form the object of the invention individually and in arbitrary combination regardless of their composition in the individual claims or their references to other claims. Furthermore, identical or similar objects are identified by the same reference symbols in the figures.

[0041] FIGS. 1a and 1b show a part of a wing with a wing-like element attached to a transition region of a wing tip device in two different three-dimensional views.

[0042] FIG. 2 shows a wing-like element in a top view.

[0043] FIGS. 3a and 3b show a detail of a connection of a wing-like element and a torque control means in an aircraft structure.

[0044] FIGS. 4a and 4b show different torque control means in schematic illustrations.

[0045] FIG. 5 shows an aircraft having a plurality of wing-like elements attached to it.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0046] FIG. 1a shows a wing 2 attached to a fuselage (not shown) of an aircraft, the wing 2 having a wing end 4, to which a wing tip device 6 is mounted. Exemplarily, the wing tip device 6 comprises a planar winglet 8 as well as a curved transition region 10 extending between a connection region 12 of the planar winglet 8 and the wing end 4 of the wing 2. The planar winglet 8 extends at an almost upright angle to an x-y-plane of the aircraft. The wing tip device 6 produces an additional structural load on the aircraft structure due to aerodynamic and mass forces, depending on the actual flight state. Exemplarily, the wing tip device 6 is shown in a flight state.

[0047] Exemplarily, a wing-like element 14 is placed on a lower side of the transition region 10 and extends in a span-wise direction, thereby leading to an increase in wing span. As indicated by a dash-dotted line, the wing-like device 14 is rotatable about a rotational axis 16, which is explained in further detail below. The wing-like element 14 comprises a leading edge 18 and a trailing edge 20, wherein the leading edge 18 faces into the flight direction x.

[0048] When the wing-like element 14 is exposed to an airflow in flight, a lift force perpendicular to the oncoming flow direction is exerted. Depending on the orientation of the wing-like element 14, i.e. the incidence angle, the lift force varies. Due to the arrangement of the wing-like element as shown in this example, a force around the x-axis of the aircraft is created, which acts on the wing 2. By adjusting the course of the incidence angle of the wing-like element 14, certain flow conditions lead to providing such a moment on the wing 2, which partially compensates those structural loads, which occur from the wing tip device 6.

[0049] The wing-like element 14 may extend in a downward and outward direction, such that exemplarily the rotational axis 16 comprises an angle β to the lateral (y) axis of the aircraft, which angle β may be in a range of 100° to 170° and preferably in a range of 115° to 135°.

[0050] In FIG. 1b the orientation of the rotational axis 16 is explained in more detail. According to e.g. ISO 1151-2, a fixed coordinate system with the principal axes x, y and z may be defined relative to the aircraft, to which the wing tip device 6 is attached. For the wing-like element 14 an auxiliary coordinate system may be defined comprising the axes x1, y1 and z1. The x1-axis is exemplarily on the x-z-plane of the fixed coordinate system of the aircraft and may be aligned to a chord 15 of the wing-like element 14. The y1-axis is perpendicular to the x1-axis and may be defined in a plane spanned up by an inner point P1 of the trailing edge 20 and by a tangent at an inner point P2 of the leading edge 18. Exemplarily, the rotational axis 16 may be parallel to the y1-axis or vice versa. Still further, for the sake of completeness, a z1-axis is perpendicular to the x1- and y1-axis according to the right-hand rule.

[0051] FIG. 2 shows the wing-like element 14 from a top view. Here, the shape of the wing-like element 14 is defined by the leading edge 18, which comprises an angle of about 45° to an auxiliary y-axis y1 in a first lateral section, which angle increases in a span-wise direction. A wing root 22 defines the auxiliary x-axis x1, from which wing root 22 the trailing edge 20 extends, which intersects with the leading edge 18. The plan form of the wing-like element 14 is therefore exemplarily triangular-like. Of course, all other shapes are suitable depending on the installation position as well as flight parameters.

[0052] In dependence of the stiffness of the wing, the sweep of the wing, the chordwise position of the wing-like element and the geometric form of the wing-like element, the rotational axis 16 comprises a certain position along the auxiliary x-axis x1, which is chosen to be forward or backward of the aerodynamic center 24, Hence, a lift force exerted on the wing-like element 14 may be considered acting on the aerodynamic center 24, such that an increase in lift leads to a rotation around the rotational axis 16, such that the incidence angle of the wing-like element 14 is decreased or increased in order to reduce the total aircraft load.

[0053] In FIG. 3a, the installation of the wing-like element 14 is schematically shown. Here, a torque control means 26 is present, which is fixedly attached to a structure 28 of the aircraft 30. An interface means 32 in form of a shaft connection, protrudes into or outside of the structure 28 and is connected to the wing root 22 of the wing-like element. The torque control means 26 is adapted for allowing a certain rotation depending on the torque introduced by the wing-like element 14. This means that with rising torque, a greater degree of rotation is allowed.

[0054] FIG. 3b shows another example, in which the interface means 32 is supported by a further connecting element 33 extending between another point of the wing root 22 of the wing-like element 14 and the torque control means 26 for counteracting a torque introduced by the wing-like element 14. For example, the connecting element 33 may be a wire or another longitudinal element capable of exemplarily transferring a tensioning force.

[0055] FIG. 4a shows a first exemplary embodiment of a torque control means 26 with a lever 34 connected to the interface means 32, to which lever 34 a spring 36 is attached, such that the spring 36 is expanded or compressed upon rotation of the interface means 32. Further, a damping unit 38 is connected to the lever 34, such that a parallel connection to the spring 36 is created. Hence, the motion of the interface means 32 is damped. Both the spring 36 and the damping unit 38 are also coupled with a structurally fixed point 37 of the aircraft 50, such as from a wing tip device, wing or fuselage.

[0056] The greater the torque introduced into the interface means 32 is, the more the spring 36 will be compressed (or expanded), such that a relationship between torque and rotational angle of the interface means 32 is created. Depending on the characteristics of the spring 36 which may be a linear or a progressive characteristic, the rotatability of the interface means 32 and, consequently, of the wing-like element 14 can be adjusted.

[0057] FIG. 4b shows another exemplary embodiment of a torque control means 26b, which comprises a rotary actuator 40, such as an electric (step) motor, which is coupled with a control unit 42, which in turn is connected to a power source 44 as well as a control command source 46, which may be a flight control computer, a control unit integrated into a load alleviation system or any other possible source, which may also be indicative of a torque introduced into the interface means 32, such as from a torque sensor 48 attached to the interface means 32.

[0058] Finally, FIG. 5 shows an aircraft 50 having a fuselage 51 and a wing 2, to which a wing tip device 6 is attached. The aircraft 50 is equipped with a wing-like element 14 at a wing tip device 6 according to the above.

[0059] Still further, as another exemplary embodiment, a canard wing 52 may be arranged in a forward portion of the fuselage of the aircraft, which may be rotatable in the same or similar manner around a rotational axis 54 as the rotatable wing-like element 14 around the rotational axis 16 at the wing tip device.

[0060] In addition, it should be pointed out that “comprising” does not exclude other elements or steps, and “a” or “an” does not exclude a plural number. Furthermore, it should be pointed out that characteristics or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other characteristics or steps of other exemplary embodiments described above. Reference characters in the claims are not to be interpreted as limitations.