Aerodynamic layout of a long endurance vertical take-off and landing folding tandem wing aircraft

Abstract

The application discloses a vertical take-off and landing long-endurance aircraft aerodynamic layout of folding and unfolding tandem wings, and belongs to the technical field of aircrafts.The aircraft aerodynamic layout comprises a fuselage, a front wing, a rear wing and a rotor.The front wing comprises an upper single-wing inner section with an upper reflex angle and a foldable outer section; the rear wing comprises a lower single-wing inner section with a lower reflex angle and a foldable outer section. In the vertical take-off and landing mode, the outer sections of the front and rear wings are folded backward and forward respectively, and the rotor is upward to form a four-rotor system; in the fixed-wing cruising mode, the outer sections of the wings are unfolded and smoothly connected with the inner sections, and the rotor provides forward thrust. The application improves the aerodynamic interference and increases the lift-drag ratio through the front and rear tandem wing layout and the design of the upper and lower reflex angle difference; the stable transition of the vertical take-off and landing and the high-efficiency cruising is realized through the synchronous folding and unfolding of the front and rear wings, the occupied space is small after folding, and the application has high reliability, high cruising efficiency and site adaptability.

Description

Technical Field

[0001] This invention belongs to the field of aircraft aerodynamic layout design, and relates to an aerodynamic layout for a vertical take-off and landing tandem wing long-endurance aircraft. Background Technology

[0002] While high-aspect-ratio fixed-wing aircraft boast long-range capabilities, their large wingspan occupies significant ground space, and their deployment is severely limited due to the reliance on wide runways for takeoff and landing. Multirotor aircraft, though capable of vertical takeoff and landing, suffer from short range and low payload. Tiltrotor aircraft, while combining the advantages of both, suffer from lower reliability due to complex tilting mechanisms and difficult tilt transitions, while still requiring a large footprint. All of these configurations have drawbacks when facing extremely confined spaces and long-duration cruising requirements.

[0003] To address the shortcomings of the aforementioned configurations, folding-wing vertical takeoff and landing (VTOL) long-endurance aircraft have been proposed in recent years. In a conventional aerodynamic layout, four rotors are mounted on a high-aspect-ratio wing to provide thrust during cruise. During takeoff and landing, the wing folds backward around a diagonal hinge, causing the four rotors to face upward, forming a quadcopter system and enabling vertical takeoff and landing. This configuration significantly reduces the footprint during takeoff and landing due to the folding wing. However, the transition from VTOL to level flight is similar to that of a tiltrotor aircraft, requiring a severe stall phase and placing extremely high demands on flight control; reliability needs further improvement.

[0004] Meanwhile, for long-endurance aircraft with conventional layouts, the horizontal stabilizer is only used for attitude control and usually generates negative lift, which reduces the aircraft's lift-to-drag ratio. To achieve the highest possible lift-to-drag ratio, wings with extremely high aspect ratios must be designed, resulting in a wing span that is much larger than its thickness and chord length, potentially leading to insufficient structural stiffness. To meet the requirements of sufficient lift and a high lift-to-drag ratio for long-endurance aircraft, a tandem wing aerodynamic layout has emerged, capable of achieving an even higher lift-to-drag ratio. This layout includes two wings, one in front and one behind. The rear wing provides beneficial interference to the front wing, while the front wing provides detrimental interference to the rear wing. Further optimization and refinement are needed to rationally arrange the relative height and position of the front and rear wings.

[0005] Therefore, there is a need in this field to further optimize the folding method and aerodynamic layout of folding-wing vertical takeoff and landing long-endurance aircraft, and a folding-wing long-endurance aircraft aerodynamic layout with higher reliability and lift-to-drag ratio is required. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an aerodynamic layout for a vertical takeoff and landing folding tandem wing long-endurance aircraft, which solves the technical problems of poor stability during the wing transition phase and insufficient flight time in the prior art.

[0007] This invention discloses an aerodynamic layout for a vertical takeoff and landing tandem-wing long-endurance aircraft, comprising a fuselage, a forward wing, a rear wing, and multiple rotors. The forward wing is located above the fuselage, and the rear wing is located below the fuselage. The forward wing includes an inner forward wing section, an outer forward wing section, and a folding mechanism, and the rear wing includes an inner rear wing section, an outer rear wing section, and a folding mechanism. The inner section of the forward wing is a high-wing monoplane with an upward dihedral angle, and the inner section of the rear wing is a low-wing monoplane with a downward dihedral angle; Multiple rotors are respectively mounted on the outer sections of the front and rear wings; The tandem-wing long-endurance aircraft has both a vertical takeoff and landing mode and a fixed-wing cruise mode. In vertical takeoff and landing mode, the outer section of the front wing folds backward relative to the inner section of the front wing via a folding mechanism, and the outer section of the rear wing folds forward relative to the inner section of the rear wing via a folding mechanism. The rotors are oriented perpendicular to the fuselage, thus forming a quadcopter system. In fixed-wing cruise mode, the outer section of the front wing unfolds through a folding mechanism and smoothly connects to the inner section of the front wing, the outer section of the rear wing unfolds through a folding mechanism and smoothly connects to the inner section of the rear wing, and the rotor is oriented parallel to the fuselage direction.

[0008] Optionally, the dihedral angle of the inner section of the forewing is 2 to 10 degrees, and the dihedral angle of the inner section of the rear wing is 2 to 10 degrees; the length ratio of the inner section of the forewing to the outer section of the forewing is 1:4, and the length ratio of the inner section of the rear wing to the outer section of the rear wing is 1:4.

[0009] Optionally, the inner sections of the front wing are symmetrically installed on the left and right sides of the front half of the fuselage and connected to the upper part of the outer wall of the fuselage; the inner sections of the rear wing are symmetrically installed on the left and right sides of the rear half of the fuselage and connected to the lower part of the outer wall of the fuselage.

[0010] Optionally, the rotor located on the outer section of the forewing and the rotor located on the outer section of the rear wing are staggered in the spanwise direction; the rotor is located at 30% of the spanwise length of the outer section of the forewing and at 35% of the spanwise length of the outer section of the rear wing.

[0011] Optionally, during the transition between vertical takeoff and landing mode and fixed-wing cruise mode, the outer sections of the front wing and the rear wing rotate synchronously, so that the rotor thrust directions on the outer sections of the front and rear wings are consistent.

[0012] Compared with the prior art, the present invention has at least the following beneficial effects: (1) Both the front and rear wings are folded down to save ground parking space to the maximum extent; (2) The aerodynamic layout of the present invention distributes the rotors on the front and rear wings, which can form an X-shaped quadcopter system during the folding and unfolding transition, which has higher stability and reliability and reduces the technical difficulty of the transition stage; (3) The fuselage adopts a tailless design and uses the differential speed adjustment of the rotor to control the yaw and pitch attitude of the aircraft, which reduces the structural weight and reduces the cruise drag. (4) Adding an upper and lower dihedral difference to the inner sections of the front and rear wings makes the front and rear wings staggered, reducing the adverse aerodynamic interference of the front wing to the rear wing, which is beneficial to improving the overall aerodynamic characteristics of the dual-wing layout, and can make the lift-to-drag ratio of the dual-wing aircraft reach or even exceed that of the conventional single-wing layout. (5) By adopting a tandem wing aerodynamic layout, a smaller span can be used while ensuring the same wing area, and a higher lift-to-drag ratio can be obtained, improving the cruise efficiency of the aircraft and reducing the structural weight, so as to carry more mission payload. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a front view of the aerodynamic layout of the vertical take-off and landing tandem wing long-endurance aircraft of the present invention in its fully folded state. Figure 2 This is a top view of the aerodynamic layout of the vertical takeoff and landing tandem wing long-endurance aircraft of the present invention in its fully folded state; Figure 3 This is a front view of the aerodynamic layout of the vertical take-off and landing tandem wing long-endurance aircraft of the present invention in its fully folded state. Figure 4 This is a schematic diagram of the fully deployed aerodynamic layout of the vertical take-off and landing tandem wing long-endurance aircraft of the present invention. Figure 5 This is a top view of the fully deployed aerodynamic layout of the vertical take-off and landing tandem wing long-endurance aircraft of the present invention. Figure 6 This is a front view of the fully deployed aerodynamic layout of the vertical take-off and landing tandem wing long-endurance aircraft of the present invention; Figure 7 This is a side view of the aerodynamic layout of the vertical take-off and landing tandem wing long-endurance aircraft of the present invention in the middle folded state. Figure 8This is a front view of the aerodynamic layout of the vertical take-off and landing tandem wing long-endurance aircraft of the present invention in its folded-down state.

[0014] Explanation of reference numerals in the attached figures: 1. Fuselage; 2. Inner section of the front wing; 3. Outer section of the front wing; 4. Folding mechanism; 5. Inner section of the rear wing; 6. Outer section of the rear wing; 7. Rotor. Detailed Implementation

[0015] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0016] A specific embodiment of the present invention, such as Figures 1-8 As shown, a vertical takeoff and landing tandem wing long-endurance aircraft is disclosed, including a fuselage 1, a front wing inner section 2, a front wing outer section 3, a folding mechanism 4, a rear wing inner section 5, a rear wing outer section 6, and a rotor 7.

[0017] Furthermore, the inner section 2 of the front wing, the outer section 3 of the front wing, and the folding mechanism 4 constitute the front wing; the inner section 5 of the rear wing, the outer section 6 of the rear wing, and the folding mechanism constitute the rear wing; the front wing is located above the fuselage 1; and the rear wing is located below the fuselage 1.

[0018] Further, see Figure 6 The inner section 2 of the forewing is a high-wing monoplane, with a length ratio of 1:4 between the inner section 2 and the outer section 3, and a certain dihedral angle, preferably within the range of 2 to 10 degrees. Two inner sections 2 are provided, symmetrically installed on the left and right sides of the front half of the fuselage 1. See [reference needed] when viewed from the forward direction. Figure 1 and Figure 2 It is located at approximately 1 / 4 of the length of fuselage 1 and is connected to the upper part of the outer wall of fuselage 1.

[0019] Further, see Figure 5 The inner section 5 of the rear wing is a low-wing monoplane, accounting for 20% of the total length of the rear wing, and has a certain dihedral angle. The length ratio of the inner section 5 to the outer section 6 of the rear wing is 1:4, preferably within the range of 2 to 10 degrees. They are symmetrically installed on the left and right sides of the rear half of the fuselage 1. See [reference needed] when viewed from the forward direction. Figure 1 and Figure 2 It is located approximately 3 / 4 of the way along the length of the fuselage and is connected to the lower part of the outer wall of fuselage 1.

[0020] Further, see Figure 3 The inner section 2 of the front wing and the inner section 5 of the rear wing form an X shape.

[0021] It is understandable that, taking the cross-section of fuselage 1 as the x-axis, the longitudinal section of fuselage 1 as the y-axis, and the forward direction as the z-axis, the upper dihedral angle is the angle of positive offset from the x-axis to the y-axis; the lower dihedral angle is the angle of negative offset from the x-axis to the y-axis.

[0022] Furthermore, the outer section 3 of the front wing has no dihedral angle and is smoothly connected to the inner section 2 of the front wing via a folding mechanism 4.

[0023] Furthermore, the outer section 6 of the rear wing has no dihedral angle and is smoothly connected to the inner section 5 of the rear wing via a folding mechanism. Furthermore, there are four rotors 7, located at 30% of the length of the outer section 3 of the front wing near the wing root in the wingspan direction, and at 35% of the length of the outer section 6 of the rear wing near the wing root in the wingspan direction. This ensures that the rotors 7 on the outer section 3 of the front wing and the rotors 7 on the outer section 6 of the rear wing are staggered by a distance in the wingspan direction, thereby reducing aerodynamic interference between the rotors.

[0024] Furthermore, there are four folding mechanisms 4, two of which are located between the inner section 2 and the outer section 3 of the front wing, and the other two are located between the inner section 5 and the outer section 6 of the rear wing.

[0025] Furthermore, the folding mechanism 4 uses an inclined hinge for its folding pivot, enabling the wing to fold backward.

[0026] The wing position and size settings of this invention can improve the overall aerodynamic characteristics of a biplane configuration, enabling the aircraft's lift-to-drag ratio to reach or even exceed that of a conventional monoplane configuration. Since both the canard and aft wings generate positive lift, the aspect ratio of the wings can be effectively reduced while maintaining the same total lift, thereby increasing the structural stiffness of the wings and improving the aircraft's lift-to-drag ratio.

[0027] In the folded state, the inner sections 2 of the front wing and 5 of the rear wing maintain an X-shaped quadcopter configuration at all times, which provides high stability and reduces the difficulty of flight control.

[0028] During flight, during the vertical takeoff and landing phase, such as Figure 1 , Figure 2 and Figure 3 As shown, the aircraft is in a folded configuration. The outer section 3 of the front wing and the inner section 2 of the front wing form a 90-degree angle, with the wingtips pointing towards the tail of the fuselage; the outer section 6 of the rear wing and the inner section 5 of the rear wing form a 90-degree angle, with the wingtips pointing towards the nose of the fuselage. The outer section 3 of the front wing is positioned directly above the rotor 7 on the outer section 6 of the rear wing. This design maximizes space utilization for easy storage and maintains the symmetry of the quadcopter configuration. (See [reference]). Figure 2The quadcopter forms a regular rectangle. Although the outer section 3 of the forewing will cause some aerodynamic interference to the rotor 7 during vertical takeoff and landing, the aerodynamic interference is weakest due to the relatively thin wing, and only minor adjustments to the quadcopter flight control system are needed. In the folded state, the quadcopter's rotor direction is perpendicular to the fuselage direction, and the quadcopter system can be used to achieve the aircraft's vertical takeoff and landing function.

[0029] During the cruise phase of a fixed-wing aircraft, such as Figure 4 , Figure 5 and Figure 6 As shown, the aircraft is in deployed configuration. The outer section 3 of the forewing and the inner section 2 of the forewing, as well as the outer section 6 of the rear wing and the inner section 5 of the rear wing, are smoothly connected, forming complete fore and rear wings with a smooth aerodynamic shape. In the deployed state, the rotors of the quadcopter are parallel to the fuselage direction, generating level flight propulsion using rotors 7. Furthermore, the quadcopter engine flight control system controls the aircraft's pitch, roll, and yaw attitudes by adjusting the speed of each engine.

[0030] During the folding transition phase (the folding transition occurs during aircraft flight), such as Figure 7 and Figure 8 As shown, the outer sections 3 and 6 of the forewing and rearwing rotate around the oblique hinge device of the folding mechanism 4 to achieve the conversion between the folded and unfolded configurations. During the folding and unfolding process, the outer sections 3 and 6 of the forewing and rearwing rotate synchronously, ensuring that the two rotors 7 on the outer section 3 and the two rotors 7 on the outer section 6 of the rearwing maintain approximately the same thrust direction. This creates a highly reliable X-shaped configuration throughout the transition. Figure 8 As shown. Compared to existing technologies that arrange all four rotors on a single wing, the aerodynamic layout of this invention distributes the rotors across the front and rear wings, forming an X-shaped quadrotor system during folding, resulting in higher stability—something existing technologies cannot achieve. Therefore, this aerodynamic layout improves flight reliability and stability during the transition process and reduces the technical difficulty of the transition. Furthermore, during the folding and unfolding process, the outer section 3 of the front wing and the outer section 6 of the rear wing never interfere with each other. This is because the outer section 3 of the front wing is higher than the outer section 6 of the rear wing in the unfolded state. (Refer to...) Figure 6 In any intermediate folded state, the position of the outer section 3 of the forewing is always higher than its initial deployed state; the position of the outer section 6 of the rear wing is always lower than its initial deployed state. Therefore, the outer section 3 of the forewing is always higher than the outer section 6 of the rear wing, and even if the folding and unfolding processes of the fore and rear wings are carried out simultaneously, the two will not interfere with each other.

[0031] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0032] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0033] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order and method of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0034] It should be understood that the foregoing only illustrates some embodiments, and changes, modifications, additions, and / or variations can be made without departing from the scope and spirit of the disclosed embodiments. These embodiments are illustrative and not restrictive. Furthermore, the described embodiments relate to those currently considered most practical and preferred, and should be understood as not being limited to the disclosed embodiments, but rather intended to cover different modifications and equivalent arrangements included within the spirit and scope of those embodiments. Moreover, the various embodiments described above can be used in conjunction with other embodiments; for example, an aspect of one embodiment can be combined with an aspect of another embodiment to achieve yet another embodiment. Additionally, individual features or components of any given component can constitute another embodiment.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. An aerodynamic layout for a vertical takeoff and landing tandem-wing long-endurance aircraft, characterized in that, It includes a fuselage (1), a front wing, a rear wing, and multiple rotors (7). The front wing is located above the fuselage (1), and the rear wing is located below the fuselage (1). The front wing includes an inner front wing section (2), an outer front wing section (3), and a folding mechanism (4). The rear wing includes an inner rear wing section (5), an outer rear wing section (6), and a folding mechanism (4). The inner section (2) of the front wing is a high-wing monoplane with an upward dihedral angle, and the inner section (5) of the rear wing is a low-wing monoplane with a downward dihedral angle; Multiple rotors (7) are respectively mounted on the outer section (3) of the front wing and the outer section (6) of the rear wing; The tandem-wing long-endurance aircraft has both a vertical takeoff and landing mode and a fixed-wing cruise mode. In vertical takeoff and landing mode, the outer section (3) of the front wing is folded backward relative to the inner section (2) of the front wing via the folding mechanism (4), and the outer section (6) of the rear wing is folded forward relative to the inner section (5) of the rear wing via the folding mechanism (4). The rotor (7) is oriented perpendicular to the fuselage (1), thus forming a quadcopter system. In fixed-wing cruise mode, the outer section (3) of the front wing is unfolded by the folding mechanism (4) and smoothly connected to the inner section (2) of the front wing, the outer section (6) of the rear wing is unfolded by the folding mechanism (4) and smoothly connected to the inner section (5) of the rear wing, and the rotor (7) is oriented parallel to the fuselage (1).

2. The aerodynamic layout of the vertical takeoff and landing tandem-wing long-endurance aircraft according to claim 1, characterized in that, The dihedral angle of the inner section (2) of the front wing is 2 to 10 degrees, and the dihedral angle of the inner section (5) of the rear wing is 2 to 10 degrees; the length ratio of the inner section (2) of the front wing to the outer section (3) of the front wing is 1:4, and the length ratio of the inner section (5) of the rear wing to the outer section (6) of the rear wing is 1:

4.

3. The aerodynamic layout of the vertical takeoff and landing tandem-wing long-endurance aircraft according to claim 1, characterized in that, The inner section (2) of the front wing is symmetrically installed on the left and right sides of the front half of the fuselage (1) and is connected to the upper part of the outer wall of the fuselage (1); the inner section (5) of the rear wing is symmetrically installed on the left and right sides of the rear half of the fuselage (1) and is connected to the lower part of the outer wall of the fuselage (1).

4. The aerodynamic layout of the vertical takeoff and landing tandem-wing long-endurance aircraft according to claim 1, characterized in that, The rotor (7) located on the outer section of the front wing (3) and the rotor (7) located on the outer section of the rear wing (6) are offset from each other in the spanwise direction; the rotor (7) is located at 30% of the spanwise length of the outer section of the front wing (3) and at 35% of the spanwise length of the outer section of the rear wing (6).

5. The aerodynamic layout of the vertical takeoff and landing tandem-wing long-endurance aircraft according to claim 1, characterized in that, During the transition between vertical takeoff and landing mode and fixed-wing cruise mode, the outer section of the front wing (3) and the outer section of the rear wing (6) rotate synchronously, so that the thrust direction of the rotors (7) on the outer sections of the front wing (3) and the rear wing (6) is consistent.

Images