Wing assembly for an aircraft

Abstract

The present invention relates to a wing assembly (10) for an aircraft having a fuselage and at least one pair of wings, the wing assembly (10) defining a flow direction (F), with respect to which the wing assembly (10) is configured to generate lift for the aircraft, the wing assembly (10) comprising: a main portion (12) configured to be fixedly attached to the fuselage so as to extend from the fuselage in the direction of extension of the wings; and a plurality of flap portions (14), each having a body portion (16), pivotally attached to the main portion (12) by pivot means (18) so as to be individually pivotable about a pivot axis (A) through a range of angular orientations including a horizontal orientation and a vertical orientation, such that in the horizontal orientation, the body portion (16) of the flap portion (14) is substantially aligned with the main portion (12) to form an elongated, substantially continuous cross-section, and in the vertical orientation, the flap portion (14) is angled downwardly relative to the main portion (12). The invention further relates to an aircraft equipped with at least one pair of such wing assemblies.

Description

Detailed Description of the Invention

[0001] The present invention generally relates to a wing assembly for an aircraft having a fuselage and at least one pair of wings, the wing assembly defining a flow direction relative to which the wing assembly is configured to generate lift for the aircraft. Additionally, the present invention also relates to an aircraft including a fuselage and at least one pair of such wing assemblies.

[0002] An aircraft that relies on wings to generate lift, in contrast to, for example, a helicopter, requires control surfaces in addition to the lift-generating surfaces. By utilizing the control surfaces in conjunction with the thrust provided by the aircraft's engines, the aircraft's parallel speed, vertical speed and attitude can be controlled within the aircraft's certified operating range according to inputs provided by the pilot. To be able to perform the aforementioned control functions, the aircraft requires actuators that can cause changes in the forces and moments acting on the aircraft to change the aircraft's speed or attitude.

[0003] One of the main technical challenges in designing and manufacturing a new type of aircraft is to find the best possible combination of actuators, lift generating surfaces, control surfaces and engines to fulfill these functions. At least some of the criteria such as the number of actuators, the complexity of the actuators and their control systems, safety margins, mass, etc. may be optimized to find the best possible combination of the parameters of the aforementioned components while keeping in mind the intended performance of the aircraft, such as maximum and cruising speed, range, maximum payload, fuel or energy consumption, etc.

[0004] While these fundamental considerations must be performed for any type of aircraft, aircraft with vertical take-off and landing (VTOL) capabilities require additional functionality to enable them to be operated in a hovering configuration, as well as to transition between hovering and cruising flight, i.e., between substantially vertical and substantially parallel flight.

[0005] To provide both VTOL capability and controllability of the aircraft in horizontal flight mode, several different approaches have been made. For example, aircraft with two custom thrust systems have been proposed, in which one thrust system provides vertical thrust and general lift for hovering, while the second thrust system provides propulsion in cruise flight. However, the provision of dual thrust systems increases the weight and complexity of each aircraft. Next, VTOL aircraft are known in which the thrust unit is rotated between a hover position and a cruise position without rotating the rest of the wing to which it is attached. Although this design overcomes the need and drawbacks of having two thrust systems, it does not take advantage of the additional possible lift that may be provided by a rotatable lift surface integrated with the thrust unit. Finally, VTOL aircraft have been proposed in which the entire wing, including the thrust systems attached to it, can be rotated between a hover configuration and a cruise configuration. However, in order to rotate the entire wing, additional control surfaces must be implemented to be able to control the aircraft in cruise flight mode with the wings and thrust units themselves oriented in positions dedicated to cruise flight.

[0006] Thus, there is still room for improvement in the design of wing assemblies for such aircraft, where lifting surfaces, control surfaces and thrust-providing engines can be integrated in an optimized manner to provide a reliable, lightweight and highly accurate integrated lift, control and propulsion system.

[0007] To this end, according to a first aspect of the invention, a wing assembly for an aircraft having a fuselage and at least one pair of wings is proposed, the wing assembly defining a flow direction against which the wing assembly is configured to generate lift for the aircraft. The wing assembly comprises a main section and a plurality of flap sections. The main section is configured to be fixedly attached to the fuselage such that it extends from the fuselage in a direction of extension of the wings. The plurality of flap sections each have a body section and are pivotally attached to the main section by pivot means such that they are individually pivotable about a pivot axis through a range of angular orientations including a horizontal orientation and a vertical orientation. In the horizontal orientation, the body section of the flap section is substantially aligned with the main section to form an elongated, substantially continuous cross section. In the vertical orientation, the flap section is angled downwards relative to the main section. The flap sections each comprise a single ducted fan engine having a cowling, an inlet and an exhaust, the ducted fan engine configured to generate thrust within a range of predetermined thrust values ​​during operation. Furthermore, each ducted fan engine is integrally formed with a body portion of a corresponding flap portion, the body portion forming a lower portion of the cowling of the ducted fan engine.

[0008] According to the first aspect, a wing assembly for an aircraft is provided with a number of individually controllable flap sections, each of which is pivotable or tiltable with respect to its angle relative to a fixed main part of the wing assembly. A single ducted fan engine is provided for each flap section to provide a highly integrated wing assembly, in which thrust vectoring is possible due to the variable angle between the flap section, i.e. the propulsion engine, and the fixed main part, i.e. the fuselage of the aircraft. The flap sections also function as control surfaces and contribute to the lift of the aircraft, particularly in a horizontal orientation. It is noted that the flow direction defined for this wing assembly substantially coincides with the horizontal flight direction of the corresponding aircraft. Providing a number of flap sections, each of which is equipped with only one individually controllable ducted fan engine, allows a highly detailed control of thrust vectoring between the ducted fan engines as well as contributing to the control and lift surfaces of the wing assembly.

[0009] According to a second aspect, the present invention relates to a wing assembly for an aircraft having a fuselage and at least one pair of wings, the wing assembly defining a flow direction relative to which the wing assembly is configured to generate lift for the aircraft. The wing assembly comprises a main section and at least one flap section. The main section is configured to be fixedly attached to the fuselage such that it extends from the fuselage in a direction of extension of the wings. The at least one flap section has a body section and is pivotally attached to the main section by pivot means such that it is pivotable about a pivot axis through a range of angular orientations including a horizontal orientation and a vertical orientation. In the horizontal orientation, the body section of the flap section is substantially aligned with the main section to form an elongated, substantially continuous cross section. In the vertical orientation, the flap section is angled downwards relative to the main section. The at least one flap section comprises at least one ducted fan engine having a cowling, an inlet and an exhaust, the at least one ducted fan engine configured to generate thrust within a range of predetermined thrust values ​​during operation. The at least one ducted fan engine is integrally formed with a body portion of the flap section, said body portion forming a lower portion of a cowling of the at least one ducted fan engine. The operating conditions of the wing assembly include a current angular orientation of the at least one flap section and a thrust currently generated by the at least one ducted fan engine. The main portion and the at least one flap section are configured such that, within at least a range of operating conditions of the wing assembly, the at least one flap section generates at least about 40% of the lift of the wing assembly. In further embodiments, the at least one flap section may generate at least about 50%, about 60% or about 70% of the lift of the wing assembly.

[0010] According to a second aspect of the invention, a wing assembly is proposed, in which at least one flap unit with at least one integrated ducted fan engine can act not only as the sole control and propulsion element of the wing assembly, but also as the substantial lifting surface, even the main lifting surface, at least within a certain range of operating conditions, including at least the current angular orientation of the at least one flap section and the thrust currently generated by the at least one ducted fan engine. Thus, all necessary forces and moments required for control and maneuverability in the wing assembly according to the invention can be generated by a combination of propulsion thrust redirection by dedicated actuators, aerodynamic forces and moments, as well as by the corresponding assemblies contributing to substantial lift, at least in some operating ranges.

[0011] According to both aspects of the invention, at least one ducted fan is pivotable / tiltable about an axis substantially perpendicular to the axis of rotation of its rotor, which allows the thrust of the ducted fan to be oriented and controlled relative to the main part of the wing assembly, i.e., the aircraft structure, while enhancing the ability to control the attitude of the aircraft. When at least one flap section is tilted about its pivot axis, the aerodynamic lift generated by the flap section is also modified. The tilting action therefore affects both the thrust direction and the lift direction, as well as the magnitude of the drag. This, combined with the ability to control and adjust the absolute value of the thrust, significantly enhances the ability to control an aircraft having such an integrated assembly.

[0012] While it is of course possible to group multiple ducted fan clusters on a single flap section in a wing assembly according to the second aspect of the invention, the general inventive concepts of the first and second aspects of the invention can also be beneficially combined when a wing assembly according to the second aspect is provided with multiple flap sections, each individually pivotable and each comprising only one ducted fan engine.

[0013] It should also be noted that according to both aspects of the invention, the direction of the pivot axis of at least one flap portion may be substantially aligned with the extension direction of the wing.

[0014] At least one flap section, having a body section which in a certain orientation acts as an extension of the cross section of the main section of the wing assembly, in any case generates lift in horizontal flight of an aircraft equipped with the wing assembly according to the invention, while in order to further increase the lift performance of the integrated flap section, the upper part and / or the side panel of the cowling of at least one ducted fan engine may be formed with a cross section in the flow direction of the aircraft such that, together with the at least one flap section in a horizontal orientation, said part of the flap / engine assembly also generates lift during the operation of the engine. Thus, designing an additional structural element associated with the ducted fan engine for generating lift in addition to the body section of the corresponding flap section may allow at least one flap section to contribute to generating at least about 40% of the lift of the wing assembly in a certain range of operating conditions.

[0015] In particular, in a cross-section in the streamwise direction of the wing assembly, the upper portion of the cowling may be formed to have a predominantly (i.e., primarily) convex curvature, preferably comprising half of a cambered airfoil section. Said section may or may not be inverted. Such a shape is optimized for minimum inlet distortion in hover conditions and maximum lift in cruise conditions.

[0016] Additionally or alternatively, the cowling upper leading edge nose radius, normalized to the cowling chord length, is between 1.8% and 5%, preferably about 2%. Such selection of the cowling upper leading edge nose radius contributes to minimizing inlet distortion in hover conditions. Also, the chord length may typically range from 600mm to 900mm, and preferably may be about 780mm.

[0017] Alternatively or additionally, in plan view of a wing assembly having at least one flap section in a horizontal orientation, the at least one flap section may form at least about 40% of the total lifting surface, wherein a wing planform associated with the wing assembly may be defined to extend to a transition between the wing assembly and a fuselage of the aircraft or further to a centerline of the aircraft.

[0018] Furthermore, the present invention relates to an aircraft comprising a fuselage, at least one pair of wings according to the first and / or second aspect of the invention, and a flight control unit for controlling the angular orientation of the flap portions and the thrust output of the ducted fan engine. Said aircraft may in particular have the above-mentioned VTOL capability.

[0019] In particular, an aircraft according to the invention may comprise at least two pairs of wing assemblies, wherein the main section and at least one flap section of at least one pair of wings according to the first and / or second aspect of the invention are configured such that, within at least a range of operating conditions of the wing assemblies, the flap section of a pair of the wing assemblies generates at least about 40% of the total lift of the entire wing of the aircraft.

[0020] In one embodiment, an aircraft may comprise two pairs of wing assemblies according to the first and / or second aspect of the invention having two different wing lengths, preferably with the pair of wings having the shorter wing length mounted in front of the other pair of wings in the horizontal flight direction of the aircraft, such that the aircraft presents a configuration with a main pair of wings and a canard pair.

[0021] In such embodiments, the wing flap section may, for example, constitute between 30% and 50%, in particular about 35%, of the total lifting surface of the wing, and the canard flap section may constitute between 50% and 70%, in particular about 61%, of the total lifting surface of the canard. Alternatively or additionally, under normal trimmed cruise conditions of the aircraft, the wing flap section may contribute between about 45% and 60%, in particular about 49%, of the total lifting surface of the wing, and / or the canard flap section may contribute between 65% and 85%, in particular about 77%, of the total lifting surface of the canard, due to the additional lift provided by the integration of the additional lifting surface in the flap / engine assembly as described above. [Brief description of the drawings]

[0022] Further features and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings, in which: [Figure 1] 1 is a cross-sectional view of a wing assembly according to the present invention; [Diagram 2] FIG. 2 is an isometric view of a single integral flap unit of a wing assembly according to the present invention. [Diagram 3] Front view of three such integral flap units. [Figure 4] 1 is a plan view of an aircraft according to the present invention having two pairs of wings. [Diagram 5] FIG. 2 is a front view of a wing assembly having multiple flap units at different angular orientations. [Figure 6] 2 is a schematic cross-sectional view of the upper cowling of the ducted fan engine of FIG. 1; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] In Figure 1 a wing assembly according to the present invention is shown in cross-section and generally designated by the reference numeral 10. The wing assembly comprises a main portion 12 configured to be fixedly mounted to a fuselage of an aircraft such that the wing assembly 10 extends from the fuselage in an extension direction W of the wing assembly 10, for example as shown in Figure 4. The wing assembly 10 defines a flow direction F with respect to which the wing assembly 10 is configured to generate lift for an aircraft in level flight.

[0024] Furthermore, the wing assembly 10 comprises a flap portion 14 having a body portion 16. The flap portion 14 is pivotally mounted to the main portion 12 of the wing assembly 10 so as to be pivotable about a pivot axis A by pivot means 18, which are only diagrammatically shown in Figure 1 and may be embodied, for example, by a servo motor.

[0025] 1 illustrates the flap portion 14 in a horizontal orientation. In the horizontal orientation, the body portion 16 of the flap portion 14 is substantially aligned with the main portion 12 of the wing assembly 10 to form an elongated, substantially continuous cross-section. The flap portion 14 may be pivotable about pivot axis A, for example through a 90° range, or may be angled downward to provide a vertical orientation, in which the main portion 12 and the body portion 16 of the flap portion 14 are substantially perpendicular to one another.

[0026] The flap section 14 further includes a ducted fan engine 20 having a cowling 22, a leading edge nose 23, an air inlet 24, an exhaust 26, a rotatable rotor 28, and a fixed stator 30. In operation, the ducted fan engine 20 generates thrust along a thrust axis T due to rotation of the rotor 28.

[0027] It should further be noted that the ducted fan engine 20 is integrally formed with the body portion 16 of the flap portion 14, said body portion 16 forming the lower portion of the cowling 22 of the ducted fan 20, the upper portion 22a of the cowling also forming a cross section in the flow direction F of the wing assembly 10 which contributes to the lift provided by the flap portion 14.

[0028] By tilting the flap section 14 about pivot axis A relative to the main section 12, the flap section 14 may act as a control surface for the wing assembly 10 while the thrust trajectory T is rotated to vary the lift provided by the flap section 14. Thus, by integrating the pivotable flap section 14 with the ducted fan engine 20, said flap section 14 can simultaneously act as an aerodynamic control surface and vector thrust, thereby providing two degrees of freedom within a single unit. The flap section 14 further contributes a substantial proportion of the lifting surface of the wing assembly 10, thereby greatly improving maneuverability and enabling higher flight speeds as compared to conventional designs.

[0029] As a result, the flap section 14 generates a significant percentage of the total aircraft lift in addition to providing independently variable thrust magnitude and thrust vectoring. Thus, the aforementioned flap section 14 is utilized in all flight phases to reduce thrust demands on the engine at slow flight speeds or to increase payload. As further seen in Figures 2 and 3 below, the design of the inlet 24 of the ducted fan engine 20, in conjunction with the geometric characteristics of the remaining elements of the flap section 14, allows for clean intake conditions at all flap section angles.

[0030] In the above figures 2 and 3, an isometric view of a single flap section 14 with an integrated ducted fan engine 20 and a front view of three such flap sections 14 are shown, respectively. It can be seen that each of the flap sections 14 carries only one ducted fan engine 20, but in other modifications of the shown embodiment, multiple ducted fan engines may be integrated in a single flap section. From figures 2 and 3, it can be further seen how the cowling 22 of the ducted fan engine 20 is aerodynamically shaped at its upper portion 22a, as well as at the side panel 22b portion of the ducted fan engine 20, in cross section, which will also contribute to generating lift together with the flap section 14 during operation of the engine 20.

[0031] 4 shows a plan view of an aircraft 100 having a fuselage 102 and two pairs of wings 10a and 10b, each of which is equipped with a flap portion as described above, with a first pair of wings 10a functioning as the main wings and a second pair of wings 10b having a shorter span functioning as the canards located in front of the main wings 10a.

[0032] The overall wing planform of wing 10a is selected such that the flap portion contributes approximately 35% of the overall wing planform, indicated by box 104, while the flap portion of canard 10b contributes approximately 61% of the total wing planform surface of canard 10b, indicated by box 106. Each wing planform is defined to extend toward centerline C of aircraft 100.

[0033] Due to the additional lift contributed by the aforementioned unique design of the flap sections 14 on the wings 10a and 10b, the flap sections of the wing 10a will contribute approximately 49% of the aforementioned total lift of the wing 10a and the flap sections of the canard 10b will contribute approximately 77% of the total lift generated by the canard 10b at the nominal, trimmed cruise condition of the aircraft 100. Thus, under the aforementioned conditions, the combination of the flap sections of the wing 10a and the flap sections of the canard 10b will generate more than 50% of the overall lift of the aircraft 100.

[0034] Additionally, FIG. 5 illustrates a front view of one of the wing 10a with all of its flap units 14 at different angular orientations to demonstrate the ability of the flap units 14 to be individually pivoted over a range of angular orientations.

[0035] Finally, in Fig. 6, a schematic cross-section in flow direction F of the upper portion 22a of the cowling 22 of the ducted fan engine 20 of Fig. 1 is shown, which cross-section minimizes inlet distortion of the air drawn into the engine 20 in hover configuration and maximizes lift in cruise configuration for each flap unit 14. In particular, the upper portion 22a of the cowling 22 is formed with a predominantly convex curvature as half of a cambered airfoil profile with a camber line CA. The dashed line in Fig. 6 indicates the theoretical lower half of said cross-section.

[0036] Furthermore, the radius R23 of the leading edge nose 23 of the upper portion 22a of the cowling 22, normalized to the chord length CL, is between 1.8% and 5%, preferably about 2%, and typically the chord length CL of such an engine 20 ranges between 600 mm and 900 mm, and may in particular be about 780 mm.

Claims

1. A wing assembly for an aircraft having a fuselage and at least one pair of wings, the wing assembly defining a flow direction (F), the wing assembly being configured with respect to the flow direction (F) to generate lift for the aircraft; a main section configured to be fixedly attached to the fuselage so as to extend from the fuselage in a direction of extension (W) of the wing; at least one flap portion having a body portion pivotally attached to said body portion by pivot means for pivotal movement about a pivot axis (A) through a range of angular orientations including horizontal and vertical orientations; in the horizontal orientation, the body portion of the flap portion is substantially aligned with the main portion to form an elongated, substantially continuous cross-section; In the vertical orientation, the flap portion is angled downwardly relative to the main portion. At least one flap portion, the at least one flap portion comprises a plurality of ducted fan engines, each ducted fan engine having a cowling, an inlet and an exhaust, each ducted fan engine configured to generate thrust within a predetermined range of thrust values ​​during operation; each said ducted fan engine being integrally formed with the body portion of the flap portion, the body portion defining a lower portion of the cowling of the at least one ducted fan engine; an operating condition of the wing assembly including an angular orientation of the at least one flap portion from the range of angular orientations and a thrust value generated by each of the ducted fan engines from the predetermined thrust value range; the main section and the at least one flap section are configured such that, within at least a range of operating conditions of the wing assembly, the at least one flap section generates at least 40% of the lift of the wing assembly; when the at least one flap portion is in a horizontal orientation, the upper and / or side panel of the cowling of each of the ducted fan engines is shaped such that a cross-section in the flow direction (F) of the wing assembly causes the upper and / or side panel of the cowling of the at least one ducted fan engine to generate lift during operation of the engine; the upper portion of the cowling having the cross section in the flow direction (F) of the wing assembly is formed with a predominantly convex curvature and includes half of a cambered airfoil profile; each said ducted fan engine has a vertical centerline, an outer surface of the upper portion of the cowling peaks at the vertical centerline of each said ducted fan engine and descends horizontally away from a respective side panel of the ducted fan engine, and the outer surface of the upper portion of the cowling of each said ducted fan engine is symmetrical about the vertical centerline of each said ducted fan engine; a radius (R23) of the upper leading edge nose of the cowling normalized to chord length (CL) is between 1.8% and 5% and / or the chord length (CL) is between 600mm and 900mm.

2. 2. The wing assembly of claim 1, comprising a plurality of flap sections, each of said plurality of flap sections being individually pivotable, each comprising a single ducted fan engine.

3. A wing assembly as described in claim 1, wherein the direction of the pivot axis (A) of at least one flap portion substantially coincides with the extension direction (W) of the wing.

4. A wing assembly as described in claim 1, wherein in a plan view of the wing assembly having at least one flap portion oriented horizontally, the at least one flap portion forms at least 40% of the total lifting surface.

5. 13. An aircraft comprising: a fuselage; at least one pair of wing assemblies according to claim 1; and a flight control unit for controlling the angular orientation of the flap section and the thrust output of the ducted fan engine.

6. 6. An aircraft as claimed in claim 5, 1. An aircraft comprising at least two pairs of wing assemblies, the main section and the at least one flap section of the at least one pair of wing assemblies being configured such that, within at least a range of operating conditions of the wing assemblies, the flap section of the pair of wing assemblies generates at least 40% of the total lift of all of the wings of the aircraft.

7. 6. An aircraft as claimed in claim 5, comprising two pairs of wing assemblies having different wing spans, the pair of wings having a shorter wing span being mounted in front of the other pair of wings in the direction of horizontal flight of the aircraft.

8. 6. The aircraft of claim 5, wherein the flap sections of a first pair of wings comprise between 30% and 50% of the total lift surface of the first pair of wings and the flap sections of a second pair of wings comprise between 50% and 70% of the total lift surface of the second pair of wings; and / or wherein under normal trimmed cruise conditions of the aircraft, the flap sections of the first pair of wings contribute between approximately 45% and 60% of the total lift of the first pair of wings and / or the flap sections of the second pair of wings contribute between 65% and 85% of the total lift of the second pair of wings.

9. The aircraft of claim 8, wherein the first pair of wings includes main wings and the second pair of wings includes canards.

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