A retractable wingtip wing for a tailless blended wing body aircraft

Abstract

The application discloses a retractable wing of a tailless blended wing body aircraft and belongs to the field of aerodynamic layout design of aircrafts. The retractable wing is located on both sides of the fuselage of the tailless blended wing body aircraft and is retracted by rotating around an axis. The horizontal projection of the retractable wing in the retracted state is surrounded by three edges. The outer edge of the horizontal projection away from the symmetry plane of the fuselage is an arc line and is coincident with the edge line of the side edge of the fuselage, the distance between the two end points of the arc line is L1=0.4L, and the distance between the end point of the arc line close to the wing root and the front edge point of the wing root is L2=0.02L. The length of the straight edge of the horizontal projection in the rear part is L3=0.16L. The inner edge of the horizontal projection close to the symmetry plane of the fuselage is a straight line. L is the horizontal projection length of the chord line of the wing root. The application can increase the low-speed high-angle-of-attack lift of the whole aircraft, generate a lifting moment and reduce the difficulty of moment balancing. The structure is simple and can effectively reduce the structural weight of the whole aircraft.

Description

Technical Field

[0001] The present invention belongs to the field of aircraft aerodynamic layout design, and in particular relates to a retractable wing strip arranged on both sides of the fuselage of a tailless wing-body fusion layout aircraft. Background Art

[0002] The tailless wing-body fusion layout is an aircraft layout form between the flying wing and the conventional layout. Compared with the flying wing layout, it has a more obvious fuselage contour, increases the available space, and retains the basic functions of the fuselage and wings. Compared with the conventional layout, the tail is eliminated and a flat lift fuselage design is adopted. The smooth transition between the fuselage and the wings greatly reduces the overall wetted area of ​​the aircraft, reduces resistance, significantly improves aerodynamic efficiency, and has relatively better stealth performance. It is one of the research hotspots for future aircraft layout forms.

[0003] One of the design challenges of tailless wing-body blended aircraft is the lack of a dedicated horizontal tail for longitudinal control. Longitudinal control is primarily achieved through control surfaces located on the fuselage and wing trailing edges. These inherently suffer from short lever arms and weak trimming capabilities. Especially in high-lift takeoff and landing configurations, the nose-down moment introduced by high-efficiency high-lift devices exacerbates trimming issues. These limitations limit their use in wing-body blended configurations, leading to widespread issues such as insufficient lift and low stall angles during low-speed takeoff and landing, making it difficult to meet performance requirements.

[0004] To meet the need for increased lift in tailless wing-body blended aircraft, most domestic and foreign aircraft use leading edge lift-enhancing devices that have little adverse effect on torque performance (small nose-down torque), such as leading edge slats, leading edge droop, and Krueger flaps. However, these devices are usually arranged along the entire span of the wing, with complex drive mechanisms and heavy structures. In addition, the construction of these lift-enhancing devices usually leaves gaps on the wing surface, which is not conducive to maintaining large-scale laminar flow to reduce aircraft drag, nor is it conducive to improving aircraft stealth performance. Therefore, it is of great significance to obtain new lift-enhancing methods with simple structures, little adverse effects on aircraft performance, and good lift-enhancing effects. Summary of the Invention

[0005] In order to overcome the shortcomings of traditional high-lift devices such as complex structure, difficulty in moment balancing, and many gaps on the wing surface, and to improve the low-speed lift performance of tailless wing-body blended layout aircraft, the present invention proposes a retractable wingtip for tailless wing-body blended layout aircraft.

[0006] The technical solution of the present invention:

[0007] A retractable slat for a tailless fusion-wing-body aircraft, wherein the retractable slats are located on both sides of the fuselage of the fusion-wing-body aircraft and are retracted and extended by rotating about an axis. The horizontal projection of the retractable slat in the retracted state is surrounded by three edges. The outer edge of the horizontal projection away from the fuselage symmetry plane is an arc and coincides with the fuselage side edge line. The distance between the two end points of the arc is L1 = 0.4L, and the distance between the end point of the arc close to the wing root and the leading edge point of the wing root is L2 = 0.02L. The length of the straight side of the rear of the horizontal projection is L3 = 0.16L. The inner edge of the horizontal projection close to the fuselage symmetry plane is a straight line. L is the horizontal projection length of the wing root chord line.

[0008] The upper and lower end surfaces of the retractable slats in the retracted state are both curved, with the lower end surface conforming to the fuselage surface. The rear end surface of the retractable slats is flat and perpendicular to the retractable slats' rotation axis. The rear end surface is bounded by a straight line and a curved line, with the curved line lying on the fuselage surface when the retractable slats are retracted. After determining the shape and size of the retractable slats, the retractable slats are removed from the fuselage surface by cutting.

[0009] The rotating shaft of the retractable winglet is installed in the fuselage. The side of the retractable winglet close to the fuselage side edge is installed on the rotating shaft through a bearing and can be deflected around the rotating shaft. The maximum deflection angle A1 is 180°.

[0010] During low-speed takeoff and landing, the retractable winglets can rotate around the axis of rotation to a position near the same plane as the wing. Their sharp side edges can roll up significant side edge vortices when the aircraft has a large angle of attack. While inducing additional vortex lift, it controls the flow separation on the wing surface, delays the stall angle of attack, and improves the aerodynamic characteristics of the entire aircraft at high angles of attack. After entering the flight state, the retractable winglets are folded up and the surface of the fuselage forms a smooth curved surface again.

[0011] Compared with the prior art, the present invention has the following outstanding effects:

[0012] 1. While increasing the overall lift of the aircraft at low speeds and high angles of attack, it also generates a pitch-down moment, reducing the difficulty of moment trimming. Conventional wing leading and trailing edge lift-enhancing devices, because the lift increment is typically located behind the aircraft's center of gravity, add an additional pitch-down moment, which exacerbates the control issues of a tailless wing-body layout. Figure 1 Comparing the lift curve 1 without winglets and the lift curve 2 with winglets, it can be seen that the winglets of the present invention can effectively improve the lift characteristics at high angles of attack and delay the stall angle of attack. Figure 2 Comparing the drag curve 3 without winglets and the drag curve 4 with winglets, the drag characteristics of the aircraft with and without winglets are similar at different angles of attack. Figure 3Comparing the pitching moment curve 5 without slats and the pitching moment curve 6 with slats, at 0° angle of attack, the pitching moment in both states is essentially the same. As the angle of attack increases, the slats reduce the pitching moment of the entire aircraft. This is particularly evident around takeoff and landing angles of attack of 8° to 10°, where the pitching moment decreases significantly, reducing the moment-balancing pressure on the entire aircraft. This shows that the slats of the present invention not only increase the lift of the entire aircraft at low speeds and high angles of attack, but also generate pitching moment. Figure 4 The pressure cloud and surface streamlines of the whole aircraft at an angle of attack of 12° are given when the wing is wingless. Figure 5 The pressure contours and surface streamlines for the entire aircraft at a 12° angle of attack with slats are presented. Without slats, flow separation occurs over most of the wing at high angles of attack, with separation spiral points and counterflow features present at the wing-body junction. With slats, the flow on the wing surface is largely downstream, influenced by the slat vortices, resulting in reduced pressure on the wing's upper surface and increased lift.

[0013] 2. A simpler structure eliminates the need for complex drive mechanisms, effectively reducing overall aircraft weight. Conventional wing leading and trailing edge lift devices are typically deployed along the wing span, with the leading edge devices typically occupying nearly the entire span. These devices also have complex drive mechanisms, resulting in significant structural weight reductions. The retractable winglets proposed in this invention are compact and feature a simple, easily implemented motion mechanism, undoubtedly resulting in significant structural weight savings.

[0014] 3. It will not cause damage to the wing surface, which is conducive to maintaining the good aerodynamic characteristics of the wing and improving the stealth performance of military aircraft. The wing is the main source of lift for the entire aircraft. The quality of the wing's aerodynamic characteristics directly affects the aerodynamic performance of the entire aircraft. Traditional lift-enhancing devices need to be cut from the wing, leaving a large number of gaps on the wing surface, which is not conducive to maintaining a large range of laminar flow on the wing surface, thereby increasing resistance. In addition, for military aircraft, the irregular gaps on the wing surface are one of the radar wave scattering edges, and more gaps will reduce the stealth performance of the aircraft. The retractable winglets proposed in the present invention are located on both sides of the fuselage, retaining the characteristics of the complete and smooth curved surface of the wing, which is conducive to maintaining the good aerodynamic characteristics of the wing. In addition, the winglets are smaller in size, leaving fewer gaps on the fuselage surface, and the adverse effects on the stealth performance of the entire aircraft will be reduced accordingly.

[0015] 4. The retractable slats are deployed for low-speed takeoff and landing, and retracted during high-speed cruising, creating no additional drag. Existing aircraft typically use slats as a fixed wing surface, which creates additional drag at high speeds. Retractable slats are deployed during use and retracted during high-speed cruising, creating no additional cruising drag. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a comparison of the lift characteristics of the wing without slats and the wing with slats;

[0017] Figure 2 It is a comparison of the drag characteristics of the wing without slats and the wing with slats;

[0018] Figure 3 It is a comparison of the pitching moment characteristics of the wing without slats and the wing with slats;

[0019] Figure 4 It is the pressure cloud and surface streamline of the whole aircraft at an angle of attack of 12° when the wing is without wing strips;

[0020] Figure 5 The pressure cloud and surface streamlines of the whole aircraft at an angle of attack of 12° when there are winglets.

[0021] Figure 6 This is a top view of the entire tailless wing-body blended layout aircraft;

[0022] Figure 7 This is a top view of the side of a tailless wing-body blended layout aircraft;

[0023] Figure 8 This is a schematic diagram of the deflection of the retractable wing strips.

[0024] Among them: 1. Lift curve when there are no fins; 2. Lift curve when there are fins; 3. Drag curve when there are no fins; 4. Lift curve when there are fins; 5. Pitching moment curve when there are no fins; 6. Pitching moment curve when there are fins; 7. Fuselage symmetry plane; 8. Slat; 9. Slat rotation axis; 10. Straight edge of the rear end surface of the slat; 11. Curved edge of the rear end surface of the slat. DETAILED DESCRIPTION

[0025] The technical solution of this application is further described below through the accompanying drawings and examples.

[0026] The top view of the tailless wing-body integrated layout aircraft is as follows Figure 6 As shown, the retractable winglets 8 provided by the present invention are located on both sides of the fuselage of the tailless wing-body fusion layout, symmetrically about the fuselage symmetry plane 7. Since the entire aircraft is geometrically symmetrical and the retractable winglets are symmetrically arranged, the present invention is described only on one side, as shown in FIG. Figure 7 shown.

[0027] The horizontal projection of the retractable side wing 8 in the retracted state is surrounded by three side lines, such as Figure 7 The shaded area is shown. The outer edge of the horizontal projection away from the fuselage symmetry plane 7 is an arc and coincides with the fuselage side edge line. The distance between the two endpoints of the arc is L1 = 0.4L. The distance between the endpoint of the arc near the wing root and the leading edge of the wing root is L2 = 0.02L. The length of the rear straight edge of the horizontal projection is L3 = 0.16L. The inner edge of the horizontal projection near the fuselage symmetry plane 7 is a straight line. L is the horizontal projection length of the wing root chord.

[0028] like Figure 8 As shown, the upper and lower end surfaces of the retractable slat 8 in the retracted state are both curved, with the lower end surface conforming to the fuselage surface. The rear end surface of the retractable slat 8 is flat and perpendicular to the retractable slat rotation axis 9. This rear end surface is bounded by a straight edge 10 and a curved edge 11. The curved edge 11 lies on the fuselage surface when the retractable slat is retracted. After determining the shape and size of the retractable slat, the retractable slat is removed from the fuselage surface by cutting.

[0029] The rotating shaft 9 of the retractable winglet is installed in the fuselage. The side of the retractable winglet close to the side edge of the fuselage is installed on the rotating shaft through a bearing and can be deflected by a maximum of 180 degrees around the rotating shaft.

[0030] In this embodiment, when the retractable wing 8 is in the retracted state, its bottom end surface forms a complete and smooth curved surface with the fuselage; in the aircraft take-off and landing state, under the drive of the motor, the retractable wing 8 rotates 180° around the rotating shaft 9, thereby entering the working state. After the aircraft enters the flight state, the retractable wing 8 is completely retracted into the interior of the fuselage, and its bottom end surface forms a complete and smooth curved surface with the fuselage again.

Claims

1. A retractable wingtip for a tailless wing-body blended aircraft, characterized in that: The retractable winglets are located on both sides of the fuselage of the wing-body fusion layout aircraft and are retracted and extended by rotating around an axis; the horizontal projection of the retractable winglets in the retracted state is surrounded by three side lines; the outer side line of the horizontal projection away from the fuselage symmetry plane is an arc line and coincides with the side edge line of the fuselage, the distance between the two end points of the arc line is L1=0.4L, and the distance between the end point of the arc line close to the wing root and the leading edge point of the wing root is L2=0.02L; the length of the straight side of the rear part of the horizontal projection is L3=0.16L; the inner side line of the horizontal projection close to the fuselage symmetry plane is a straight line; and L is the horizontal projection length of the wing root chord line.

2. The retractable wing of a tailless wing-body blended aircraft according to claim 1, characterized in that: The upper and lower end surfaces of the retractable wingtip in the retracted state are both curved surfaces and the lower end surface is in contact with the fuselage surface; the rear end surface of the retractable wingtip is a plane and is perpendicular to the retractable wingtip rotation axis; the rear end surface is surrounded by a straight line and a curve, and the curve is located on the fuselage surface when the retractable wingtip is retracted; after determining the shape and size of the retractable wingtip, the retractable wingtip is obtained from the fuselage surface by cutting.

3. The retractable wing of a tailless wing-body blended aircraft according to claim 1, characterized in that: The rotating shaft of the retractable wing is installed in the fuselage. The side of the retractable wing close to the fuselage side edge is installed on the rotating shaft through a bearing and can be deflected around the rotating shaft. The maximum deflection angle A1 is 180°.

4. The retractable wing of a tailless wing-body blended aircraft according to claim 1, characterized in that: During low-speed takeoff and landing, the retractable winglets can rotate around the axis of rotation to a position near the same plane as the wing. Their sharp side edges can roll up significant side edge vortices when the aircraft has a large angle of attack. While inducing additional vortex lift, it controls the flow separation on the wing surface, delays the stall angle of attack, and improves the aerodynamic characteristics of the entire aircraft at high angles of attack. After entering the flight state, the retractable winglets are folded up and the surface of the fuselage forms a smooth curved surface again.

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