Semi-annular empennage structure for aircraft

Abstract

The semi-annular empennage structure extends upwards along an arc-shaped path to form a semi-annular pneumatic structure with a downward opening, and the front edge of the semi-annular pneumatic structure is of a sweepback structure; three mutually independent deflection control surfaces are arranged on the rear edge of the semicircular empennage; the semicircular empennage is composed of a hard hollow skin and an empennage framework; the three deflection control surfaces are composed of hard solid plates and deflection connecting rods; and the deflection connecting rod is supported on the empennage framework and is operated by the actuator to rotate. According to the semi-annular empennage structure, a lower closed frame is omitted, the number and the length of internal supporting web plates can be reduced by adopting a hard structure, enough rigidity can be provided by depending on the hard structure, and compared with an annular empennage or a full-motion arc empennage, the structural mass is reduced, and meanwhile, enough rigidity and aerodynamic stability are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft tail wing design, in particular to a semi-annular tail wing structure suitable for fixed-wing aircraft, and more particularly to a semi-annular tail wing structure for an aircraft. BACKGROUND

[0002] In the tail wing design of existing aircraft, various non-traditional tail wing structure schemes have emerged to meet the needs of drag reduction, weight reduction, and specific layout adaptation. However, these structures generally have high complexity, weight increase, unstable aerodynamic response, and maintenance difficulties in actual engineering.

[0003] For example, US Patent US 5242132 A discloses a multi-body ship V-STOL aircraft that uses a whole hinged arc tail wing to achieve three-axis compound deflection through a hinge connected to the fuselage, in order to reduce drag and weight with a single structure. However, this scheme has structural defects that are difficult to overcome: large-size arc surfaces require super-high power actuators for three-axis movement, resulting in a dramatic increase in the weight of the drive system, which offsets the weight reduction advantage; the nonlinear drift of the aerodynamic center position during compound motion of irregular arc surfaces makes attitude control response difficult to predict and lacks sufficient dynamic aerodynamic verification; the three-axis motion hinge system has no redundancy design, and a single point failure can cause omnidirectional loss of control, posing a serious safety hazard.

[0004] For another example, US Patent US 6592073 B1 discloses a twin-fuselage amphibious aircraft with a tail wing structure that integrates the rudder surface into the ducted propeller housing, but is limited by the diameter of the propeller, resulting in a short and thick tail shape and a significant increase in drag; the limited area of the ducted rudder surface results in insufficient control torque, leading to slow aerodynamic response in high angle of attack or engine failure conditions; at the same time, the aerodynamic interference between the propeller wake and the rudder surface not only easily causes nonlinear control response, but also can induce structural resonance and reduce propulsion efficiency. In addition, maintenance of this structure requires disassembly of the rudder surface assembly, which is complex and can easily damage the aerodynamic layout.

[0005] For another example, International Patent WO 2008 / 081098 A1 proposes a ring tail wing scheme that forms a ring-shaped channel around the propeller by closing the horizontal wing and vertical wing to achieve drag reduction and noise reduction. However, at high angles of attack, the ring-shaped frame causes the rudder surface to be blocked by the fuselage tail, resulting in a significant decrease in airflow control capability; the large-span ring-shaped frame is prone to stress concentration at the fuselage connection, necessitating an increase in structural weight; the propeller wake directly impacts the ring wall, easily causing material ablation and rudder efficiency decline, and maintenance of the ring tail wing requires extensive disassembly, which is time-consuming and disrupts the aerodynamic integrity.

[0006] In summary, although the existing non-conventional tail wing structure has some innovation in aerodynamic layout, it has the following shortcomings: complex structure, weight increase, large actuator demand, many connection nodes, difficult to achieve weight reduction target, unstable aerodynamic performance, obvious rudder efficiency attenuation in composite motion or specific flight state, insufficient attitude control precision, insufficient safety redundancy, single point failure of some structures may cause serious flight risk, poor maintainability, high coupling degree of tail wing and propulsion system layout, high disassembly and repair cost and easy to affect aerodynamic integrity.

[0007] These defects show that the existing tail wing design cannot balance between drag reduction, control performance, structural safety and maintenance convenience, and a new type of tail wing scheme with simpler structure, stable aerodynamic performance, redundant safety guarantee and convenient maintenance is needed to balance lightweight and reliability. SUMMARY

[0008] The technical problem to be solved by the present application is to provide a semi-ring tail wing structure for an aircraft to reduce or avoid the problems mentioned above.

[0009] To solve the above technical problems, the present application provides a semi-ring tail wing structure for an aircraft, which is arranged at the tail of the aircraft. The semi-ring tail wing starts from below the wing and extends upward along an arc path to form a semi-ring aerodynamic structure with an opening downward, the highest point of the arc extension is located behind the end of the tail of the aircraft, and the leading edge is in a backward swept configuration. The trailing edge of the semi-ring tail wing is provided with three mutually independent deflection rudders, each rudder is controlled by an actuator. The semi-ring tail wing is composed of a hard hollow skin and a tail wing skeleton integrally formed in the interior of the hard hollow skin. The three deflection rudders are composed of a hard solid plate and a deflection connecting rod integrally formed in the interior of the hard solid plate. The deflection connecting rod is supported on the tail wing skeleton and is operated to rotate by the actuator.

[0010] Preferably, the hard hollow skin and the hard solid plate are made of carbon fiber composite material.

[0011] Preferably, the trailing edge of the hard hollow skin is provided with three trailing edge mounting notches for accommodating the three deflection rudders. The tail wing skeleton includes three main beams corresponding to the deflection connecting rods of the three deflection rudders. The three main beams are correspondingly arranged in the interior of the trailing edge mounting notches.

[0012] Preferably, the main beam is provided with a plurality of longitudinal webs extending into the interior of the hard hollow skin, and is provided with two connecting lugs outward of the mounting notches. The deflection connecting rod of the deflection rudder is provided with two lug seats rotatably connected with the connecting lugs.

[0013] Preferably, a crank is arranged between the two ear seats of the deflection link, one end of the crank extends into the interior of the hard solid plate of the deflection surface, and the other end is rotatably connected with the actuator.

[0014] Preferably, the actuator is arranged in the interior of the hard hollow skin, the hard hollow skin is provided with a mounting opening corresponding to the position of the actuator and a cover plate, the cover plate is provided with an actuating gap for the actuating end of the actuator to extend out.

[0015] Preferably, the tail skeleton further comprises tail connecting box beams arranged on both sides of the three main beams, the tail connecting box beams are provided with at least one longitudinal web extending into the interior of the hard hollow skin, and a connecting box body is arranged at the end of the tail connecting box beams.

[0016] Preferably, the starting end of the semi-annular tail is rigidly connected to the lower wing through a connecting rod, and the semi-annular tail is fixedly connected with the connecting rod through the connecting box body of the tail connecting box beam.

[0017] Preferably, the three deflection surfaces include a central surface symmetrically arranged along the longitudinal axis of the aircraft, and two lateral surfaces symmetrically arranged on both sides of the central surface.

[0018] Compared with the prior art, the semi-annular tail structure of the present application has the following advantages: (1) significant weight reduction advantage. The semi-annular open structure eliminates the lower closed frame, and compared with the annular tail or full-arc tail, the structural weight is reduced while maintaining sufficient rigidity and aerodynamic stability. (2) Aerodynamic interference is reduced. The connection area of the semi-annular tail is located below the wing, and the high-speed airflow on the upper surface of the wing can avoid the connection area, reducing aerodynamic interference and improving airflow adhesion. (3) The control performance is improved. The lower open structure and the swept-arc arrangement enable the tail surface to avoid the obstruction of the tail of the fuselage at high angles of attack, maintain effective airflow action, and prevent the control effectiveness from being attenuated or the control from failing at high angles of attack. (4) Maintenance is enhanced. The lower open structure provides more accessible space for the fuselage below the tail and the tail propulsion device, improving the maintainability and maintenance efficiency of the tail structure and power system. BRIEF DESCRIPTION OF DRAWINGS

[0019] The following drawings are only intended to illustrate and explain the present application, and do not limit the scope of the present application.

[0020] Figure 1 is a top view of a semi-annular tail aircraft according to one embodiment of the present application.

[0021] Figure 2 is a bottom view of a semi-annular tail aircraft according to another embodiment of the present application.

[0022] Figure 3is a top view of a semi-annular tail aircraft according to another embodiment of the present application.

[0023] Figure 4 is a side view of a semi-annular tail aircraft according to another embodiment of the present application.

[0024] Figure 5 is a top view of a semi-annular tail structure according to an embodiment of the present application.

[0025] Figure 6 is a sectional view of a semi-annular tail structure according to another embodiment of the present application.

[0026] Figure 7 is a bottom view of a semi-annular tail structure according to another embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals.

[0028] In view of the problems existing in the prior art, the present application provides a tail structure for an aircraft, in particular to a semi-annular tail 1, as shown in Figures 1-4 which shows a structural schematic view of a semi-annular tail aircraft according to an embodiment of the present application, wherein the semi-annular tail 1 of the present application is arranged at the tail of the aircraft.

[0029] Unlike the existing tail designs mentioned in the conventional and background art sections, the semi-annular tail 1 of the present application starts from below the wing and extends upward along an arc-shaped path to form a semi-annular aerodynamic structure with an opening downward, the highest point of the arc-shaped extension is located behind the end of the tail of the aircraft, and the leading edge 12 is in a backward-swept configuration.

[0030] The tail structure of the present application adopts a semi-annular open structure, which has obvious weight reduction advantages over the prior art. The semi-annular tail extends upward from below the wing, and the high-speed airflow on the upper surface of the fuselage avoids the connection area of the semi-annular tail, avoiding the interference of the airflow on the aerodynamic shape of the tail; and the open structure of the lower part of the semi-annular tail and the backward-swept configuration beyond the end of the tail of the aircraft effectively avoid the obstruction of the tail structure of the fuselage tail to the control airflow in the high angle of attack state, avoiding the problem of control surface failure in the high angle of attack state; at the same time, since the tail structure does not obstruct the tail of the fuselage, it is also convenient for maintenance of the fuselage and engine below the tail.

[0031] In one embodiment, the starting end of the semi-circular tail is rigidly fixed to the underside of the wing by a connecting rod 13 extending along the longitudinal axis of the aircraft. In another embodiment, the connecting rod 13 is a double rod structure symmetrically arranged under the two wings.

[0032] In one embodiment, for example, the semi-circular tail (airfoil: NACA 0012) can be made of carbon fiber composite material, and the semi-circular tail starts from the underside of the wing 15-50 cm away from the fuselage. The tail extends upward along an arcuate path, and the highest point of the leading edge of the semi-circular tail is 0.5-0.8 times the chord length of the tail airfoil section above the horizontal plane passing through the end of the tail of the aircraft, and the sweepback angle of the leading edge relative to the horizontal plane passing through the longitudinal axis of the fuselage is 25-50 degrees. Two titanium connecting rods (diameter 10-15 cm) rigidly connect the starting end of the tail to the lower surface of the wing, and the rods are spaced 0.5-0.8 m away from the side walls of the fuselage (to avoid the turbulent flow region of the fuselage).

[0033] Further, in the illustrated embodiment, a propeller is mounted at the end of the tail of the aircraft, and the disc plane of the propeller is arranged to avoid spatial interference with the highest point of the semi-circular tail. In one embodiment, for example, a turboprop engine can be installed at the tail of the aircraft.

[0034] Further, in one embodiment, the airfoil section of the semi-circular tail along the arcuate extension path remains consistent except in the connection region, to ensure the continuity of the aerodynamic shape and optimize the flow field, while reducing the manufacturing difficulty.

[0035] Further, in one embodiment, the trailing edge of the semi-circular tail is provided with three independently deflecting surfaces, each controlled by an actuator.

[0036] Specifically, as shown, the three deflecting surfaces include a central surface symmetrically arranged along the longitudinal axis of the aircraft, and two lateral surfaces symmetrically arranged on both sides of the central surface, which are distributed circumferentially along the trailing edge of the semi-circular tail. For example, the three deflecting surfaces can be equally distributed along the trailing edge of the tail, wherein the deflecting range of the central surface is ±30°, and the deflecting range of the lateral surfaces is ±25°.

[0037] The semi-annular tail fin of the present application can obviously accelerate the airflow along the arc surface, delay the airflow separation, and reduce the cruising resistance by 15% in a wind tunnel test at a speed of 200 kilometers per hour, wherein the horizontal distance between the highest point of the leading edge of the tail fin and the tail end of the aircraft is 0.5 times the chord length of the tail fin airfoil section, and the sweepback angle of the leading edge of the tail fin is 25 degrees. In addition, the semi-annular tail fin of the present application can still be stably controlled at a large angle of attack (α = 25°), while the traditional T-shaped tail fin enters a rudder failure state when α > 20°, and the average stall angle of attack of the relative traditional tail fin structure can be increased by about 8 degrees (based on CFD turbulent energy analysis). After experimental verification, the rudder efficiency of the yaw-rolling decoupling control of the present application can be increased by about 2 times relative to US 5242132 A, especially at a large angle of attack (α = 25°), the pitch moment coefficient can be increased from 0.08 to 0.16, and the crosswind landing accuracy can be increased by more than 30% (Monte Carlo simulation 1000 times).

[0038] Moreover, the semi-annular tail fin of the present application avoids the tail structure of the fuselage, avoids the slipstream shock vibration, and improves the fatigue life of the tail structure, for example, through 2000 hours of bench vibration test, the fatigue life of the tail structure of the present application is increased by 2.5 times on average relative to the traditional T-shaped tail fin; at the same time, through comparative experiments, the tail fin of the present application (the horizontal distance between the highest point of the leading edge and the tail end of the aircraft is 0.8 times the chord length of the tail fin airfoil section, and the sweepback angle of the leading edge of the tail fin is 50 degrees) reduces the noise by 7dB (FAR 36 standard measuring point) relative to US6592073 B1 due to the avoidance of the interference of the duct flow. In terms of tail maintenance, the open structure of the tail fin of the present application reduces the maintenance time from 4 hours to 1.5 hours relative to the traditional T-shaped tail fin.

[0039] Overall, the semi-annular tail fin of the present application can accelerate the airflow speed in terms of aerodynamic efficiency. For example, when the horizontal distance between the highest point of the leading edge of the semi-annular tail fin and the tail end of the aircraft is 0.7 times the chord length of the tail fin airfoil section, and the sweepback angle of the leading edge of the tail fin is 35 degrees, the boundary layer separation point is delayed to 85% of the chord length position (verified by infrared thermal imaging), and the lift-drag ratio is increased to 9.2 relative to the traditional T-shaped tail fin (increased by 7.1 relative to the traditional tail fin). The open structure of the annular tail fin of the present application shows that local damage only causes single rudder failure in the ballistic impact test (as a comparison, the annular tail fin of WO 2008 / 081098 A1 is unstable as a whole), and the redundant rudder can maintain controllable flight, and the structure is reduced by 15% relative to the B737-800 avionics simulator structure, and the fuel efficiency is increased by more than 12%.

[0040] Further, as Figures 5-7As shown, in the semi-annular tail structure of the present invention, the semi-annular tail 1 is composed of a rigid hollow skin 21 and a tail fin frame 22 integrally formed inside the rigid hollow skin 21; the three deflection control surfaces are composed of a rigid solid plate 23 and a deflection linkage 24 integrally formed inside the rigid solid plate 23; the deflection linkage 24 is supported on the tail fin frame 22 and is operated to rotate by an actuator 25.

[0041] In one specific embodiment, both the rigid hollow skin and the rigid solid plate can be made of carbon fiber composite material. Since the aerodynamic forces borne by the tail fin are relatively small, the tail fin airfoil can adopt a small thickness cross section. Therefore, the rigid structure using carbon fiber composite material can reduce the number and length of the internal supporting web, and the rigid structure itself can provide sufficient rigidity.

[0042] Furthermore, as shown in the figure, the trailing edge of the rigid hollow skin 21 is provided with three trailing edge mounting notches 211 for accommodating the three deflection control surfaces; the tail fin frame 22 includes three main beams 221 that correspond to the deflection connecting rods 24 supporting the three deflection control surfaces; the three main beams 221 are respectively disposed inside the trailing edge mounting notches 211.

[0043] The main beam 221 is provided with a plurality of longitudinal web plates 222 extending into the interior of the rigid hollow skin 21, and is provided with two connecting lugs 223 facing the outside of the mounting notch 211. The deflection connecting rod 24 of the deflection rudder surface is provided with two lug seats 243 that are rotatably connected to the connecting lugs 223.

[0044] An actuating crank 244 is disposed between the two lug seats 243 of the deflection linkage 24. One end of the actuating crank 244 extends into the interior of the rigid solid plate 23 of the deflection rudder surface, and the other end can be connected by a connecting rod (such as...). Figure 6 (As shown in the cross-sectional view) is rotatably connected to the actuator 25.

[0045] The actuator 25 is disposed inside the rigid hollow skin 21. The rigid hollow skin 21 is provided with a mounting opening 251 corresponding to the position of the actuator 25 and a cover plate 252. The cover plate 252 is provided with an actuation notch 253 for the actuating end of the actuator 25 to extend out. Figure 7 As shown.

[0046] The tail fin frame 22 also includes tail fin connecting box beams 225 disposed on both sides of the three main beams 221. The tail fin connecting box beams 225 are provided with at least one longitudinal web plate 222 extending into the interior of the rigid hollow skin 21, and a connecting box 227 is provided at its end. The semi-annular tail fin is fixedly connected to the connecting rod 13 through the connecting box 227 of the tail fin connecting box beams 225.

[0047] The three main beams 221 and the tail wing connecting box beam 225 are fixedly connected to each other by connecting pieces to form the tail wing framework 22.

[0048] The semi-annular tail wing structure of the present application omits the lower closed frame, adopts a hard structure to reduce the number and length of internal support webs, and relies on the hard structure itself to provide sufficient rigidity, compared with annular tail wings or full-arc tail wings, the structural mass is reduced while sufficient rigidity and aerodynamic stability are provided.

[0049] Those skilled in the art should understand that, although the present application is described in the manner of multiple embodiments, not every embodiment contains only one independent technical solution. The description in the specification is merely for the sake of clarity, those skilled in the art should understand the specification as a whole and understand the technical solutions involved in each embodiment as being combined into different embodiments to understand the protection scope of the present application.

[0050] The above description is merely illustrative of the specific embodiments of the present application, and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by those skilled in the art without departing from the concept and principles of the present application shall fall within the scope of the present application.

Claims

1. A semi-annular tail structure for an aircraft, disposed at the tail of the aircraft; characterized in that, The semi-circular tail fin originates below the wing and extends upward along an arc-shaped path to form a downward-facing semi-circular aerodynamic structure. The highest point of its arc extension is located behind the tail end of the aircraft, and its leading edge has a swept-back configuration. The trailing edge of the semi-circular tail fin has three independent deflection control surfaces, each controlled by fly-by-wire via actuators. The semi-circular tail fin is composed of a rigid hollow skin and a tail fin frame integrally formed inside the rigid hollow skin. The three deflection control surfaces are composed of a rigid solid plate and a deflection linkage integrally formed inside the rigid solid plate. The deflection linkage is supported on the tail fin frame and rotated by the actuators.

2. The semi-annular tail fin structure as described in claim 1, characterized in that, Both the rigid hollow skin and the rigid solid plate are made of carbon fiber composite material.

3. The semi-annular tail fin structure as described in claim 1, characterized in that, The trailing edge of the rigid hollow skin is provided with three trailing edge mounting notches to accommodate the three deflection control surfaces; the tail fin frame includes three main beams that correspondingly support the deflection linkages of the three deflection control surfaces; the three main beams are correspondingly located inside the trailing edge mounting notches.

4. The semi-annular tail fin structure as described in claim 3, characterized in that, The main beam is provided with multiple longitudinal webs extending into the interior of the rigid hollow skin, and two connecting lugs facing the outside of the mounting notch are provided. The deflection linkage of the deflection rudder surface is provided with two lug seats that are rotatably connected to the connecting lugs.

5. The semi-annular tail fin structure as described in claim 4, characterized in that, An actuating crank is provided between the two lug seats of the deflection linkage. One end of the actuating crank extends into the interior of the solid plate of the deflection rudder surface, and the other end is rotatably connected to the actuator.

6. The semi-annular tail fin structure as described in claim 5, characterized in that, The actuator is disposed inside the rigid hollow skin. The rigid hollow skin is provided with a mounting port and a cover plate corresponding to the position of the actuator. The cover plate is provided with an actuation notch for the actuating end of the actuator to extend out.

7. The semi-annular tail fin structure as described in claim 6, characterized in that, The tail wing frame also includes tail wing connecting box beams set on both sides of the three main beams. The tail wing connecting box beams are provided with at least one longitudinal web plate extending into the interior of the rigid hollow skin, and a connecting box is provided at its end.

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