A tiltrotor aircraft

Abstract

This invention discloses a tiltrotor aircraft, relating to the field of tiltrotor aircraft design technology. It includes a fuselage with an overall spindle-shaped profile and an inverted trapezoidal cross-section. The outer peripheral surface of the fuselage includes an upper surface, a lower surface, and two side surfaces. The two side surfaces are connected between the upper and lower surfaces and are located on opposite sides of the fuselage. The upper surface, lower surface, and two side surfaces are all composed of complete swept surfaces, each formed by a straight-line sweep. This achieves coordinated suppression of the aircraft's full radar cross-section and aerodynamic noise, enhancing its survivability.

Description

Technical Field

[0001] This invention relates to the field of tiltrotor aircraft design technology, and in particular to a tiltrotor aircraft. Background Technology

[0002] Tiltrotor aircraft, with their combined advantages of vertical takeoff and landing, hovering, and high-speed cruise, have become a new generation of aircraft integrating the core characteristics of helicopters and fixed-wing aircraft, showing broad application prospects. However, with the multidimensional development of detection technologies, tiltrotor aircraft face the dual challenges of radar and acoustic detection: First, insufficient radar stealth performance. The shape design of the fuselage, wings, nacelles, and rotor system of traditional tiltrotor aircraft has not fully considered RCS suppression, and the fuselage still uses a large number of non-streamlined cross sections. Second, insufficient aerodynamic noise suppression. Traditional tiltrotor aircraft have high noise sound pressure levels, which can easily reveal mission location. In addition to noise reduction through rotor aerodynamic shape design, it is also necessary to consider the impact of blade shape on radar stealth performance and achieve synergistic suppression of radar cross section and aerodynamic noise. Currently, there is still a lack of mature design solutions. In summary, existing tiltrotor aircraft have technical shortcomings in terms of radar cross section and comprehensive aerodynamic noise suppression. There is an urgent need for a complete component shape design scheme to break through the bottleneck of radar / noise integrated stealth and improve its survivability and application adaptability in complex environments. Summary of the Invention

[0003] The purpose of this invention is to provide a tiltrotor aircraft to solve the problems existing in the prior art, achieve synergistic suppression of the aircraft's full radar cross section and aerodynamic noise, and improve its survivability.

[0004] To achieve the above objectives, the present invention provides the following solution: The present invention provides a tiltrotor aircraft, including a fuselage, the fuselage having an overall spindle-shaped profile, the cross-section of the fuselage having an inverted trapezoidal structure, the outer peripheral surface of the fuselage including an upper surface, a lower surface and two side surfaces, the two side surfaces being connected between the upper surface and the lower surface and located on both sides of the fuselage respectively, the upper surface, the lower surface and the two side surfaces being composed of complete swept surfaces, each swept surface being formed by sweeping straight lines.

[0005] Optionally, the fuselage outline viewed from above is spindle-shaped and includes a straight nose, a straight tail, and a spindle-shaped upper surface outline, the upper surface of which is formed by the straight nose sweeping along the spindle-shaped upper surface outline to the straight tail.

[0006] Optionally, the fuselage outline viewed from the front is an inverted trapezoid, with the two sides of the fuselage forming an angle A with the horizontal plane. The sides are formed by a straight line with an angle A with the horizontal plane sweeping along the upper surface outline of the spindle-shaped fuselage from the straight nose to the straight tail.

[0007] Optionally, the outline of the fuselage as viewed from the side is formed by an upper outline and a lower outline, wherein the upper outline and the lower outline are the upper and lower outlines of the side of the fuselage, respectively, and both the upper outline and the lower outline are in the shape of splines.

[0008] Optionally, the fuselage is connected to two symmetrically distributed wings, and the ends of the wings away from the fuselage are connected to nacelles. The front end of the nacelle is provided with a rotor hub, and multiple rotor blades are installed on the rotor hub. The nacelle is provided with a transmission component that is drivenly connected to the rotor hub. The nacelle is directly scaled down from the fuselage as a whole, and the tail of the nacelle has a slanted structure.

[0009] Optionally, from a side view, the outer contour of the nacelle includes an upper nacelle contour and a lower nacelle contour. The upper nacelle contour and the lower nacelle contour are respectively the upper and lower contours of the side of the nacelle. The upper nacelle contour is directly scaled from the upper contour of the fuselage, and the lower nacelle contour is directly scaled from the lower contour of the fuselage. The tail of the nacelle is a beveled structure, forming the tail beveled contour of the side profile of the nacelle. From a top view, the outer contour of the nacelle includes two side contours, which are directly scaled from the fusiform upper surface contour. From a forward view, the outer perimeter of the nacelle is hexagonal, with the top and bottom edges of the outer perimeter parallel to the horizontal plane, and the angles formed by the other four hypotenuses and the horizontal plane being the same as the included angle A.

[0010] Optionally, the blade is provided with a blade tip, which has a downward and swept-back structure.

[0011] Optionally, the dihedral angle of the propeller tip is 9.2°, the sweep angle of the propeller tip is 11.7°, and the distribution range of the propeller tip on the propeller blade is from 0.89R to 1.0R, where R is the radius of the propeller blade.

[0012] Optionally, the fuselage is connected to two symmetrically distributed wings and two symmetrically distributed tail fins. The wings are forward-swept wings, and the tail fins are anhedral V-shaped tail fins. The forward sweep angle of the wings and the backward sweep angle of the tail fins are the same.

[0013] Optionally, the dihedral angle of the tail fin is 30.2°, and the forward sweep angle of the wing and the backward sweep angle of the tail fin are both 6.7°.

[0014] The present invention achieves the following technical effects compared to the prior art: The tiltrotor aircraft disclosed in this invention reduces the radar cross section and radar wave reflection by designing its fuselage as a spindle-shaped profile and designing the upper surface, lower surface and both sides as straight swept curved surfaces. At the same time, it optimizes the aerodynamic streamline and reduces the aerodynamic noise level, thereby shortening the radar / noise detection range. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is an isometric view of the overall shape of a tiltrotor aircraft, as disclosed in an example of the present invention. Figure 2 This is a top view of the outer contour of the fuselage of a tiltrotor aircraft in one example disclosed in this invention; Figure 3 This is a side view of the outer contour of the fuselage of a tiltrotor aircraft, as disclosed in an example of the present invention. Figure 4 This is a front view of the outer contour of the fuselage of a tiltrotor aircraft, as disclosed in an example of the present invention. Figure 5 This is a rear view of the fuselage-wing-tail in one example disclosed in this invention; Figure 6 This is a top view of the fuselage-wing-tail section in one example disclosed in this invention; Figure 7 This is a side view of a rotor hub-nacelle example disclosed in this invention; Figure 8 This is a top view of a propeller hub-nacelle example disclosed in this invention; Figure 9 This is a front view of a rotor hub-nacelle example disclosed in this invention; Figure 10 This is a top view of the blade shape in an example disclosed in this invention; Figure 11 This is a front view of the blade shape in an example disclosed in this invention; Among them, 1-fuselage, 2-wing, 3-tail, 4-propeller tip, 5-inner section, 6-propeller hub, 7-nacelle, 8-straight nose, 9-fuselage upper surface profile, 10-straight tail, 11-upper fuselage profile, 12-lower fuselage profile, 13-upper nacelle profile, 14-side profile, 15-lower nacelle profile, 16-tail oblique profile. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The purpose of this invention is to provide a tiltrotor aircraft to solve the problems existing in the prior art, achieve synergistic suppression of the aircraft's full radar cross section and aerodynamic noise, and improve its survivability.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] like Figures 1 to 11 As shown, this invention provides a tiltrotor aircraft, including a fuselage 1. The fuselage 1 has an overall spindle-shaped profile, that is, both ends are tapered and approximately symmetrical. The cross-section of the fuselage 1 has an inverted trapezoidal structure. The outer peripheral surface of the fuselage 1 includes an upper surface, a lower surface, and two side surfaces. The two side surfaces are connected between the upper and lower surfaces and are located on both sides of the fuselage 1. The upper surface, lower surface, and two side surfaces are all composed of complete swept surfaces, each swept by a straight line, that is, a straight-line swept surface. The tiltrotor aircraft disclosed in this invention, by designing its fuselage 1 as an overall spindle-shaped profile and designing the upper surface, lower surface, and two side surfaces as straight-line swept surfaces, reduces the radar cross-section, reduces radar wave reflection, and optimizes aerodynamic streamlines, reducing aerodynamic noise levels, thereby shortening the radar / noise detection range.

[0021] Based on the above implementation methods, and through experimental verification, the tiltrotor aircraft disclosed in this invention has an average radar cross-section reduction of 15.8 dB and a maximum reduction of over 20 dB across the entire angular domain, and an average aerodynamic noise reduction of 1.4 dB and a maximum reduction of 3.4 dB.

[0022] Specifically, in some embodiments, the fuselage 1, viewed from above, has a spindle-shaped outline and includes a straight nose 8, a straight tail 10, and a spindle-shaped upper surface outline 9. The upper surface of the fuselage 1 is formed by the straight nose 8 sweeping along the spindle-shaped upper surface outline 9 to the straight tail 10. Based on all the above embodiments, the fuselage 1, viewed from the front, has an inverted trapezoidal outline. The two sides of the fuselage 1 form an angle A with the horizontal plane. The sides are formed by a straight line with an angle A with the horizontal plane sweeping along the spindle-shaped upper surface outline 9 from the straight nose 8 to the straight tail 10. Furthermore, based on all the above embodiments, the fuselage 1, viewed from the side, is formed by an upper fuselage outline 11 and a lower fuselage outline 12. The upper fuselage outline 11 and the lower fuselage outline 12 are the upper and lower outlines of the sides of the fuselage 1, respectively, and both the upper fuselage outline 11 and the lower fuselage outline 12 are spline shapes.

[0023] In one embodiment, the fuselage 1 is connected to two symmetrically distributed wings 2. The ends of the wings 2 away from the fuselage 1 are connected to nacelles 7. The front end of the nacelle 7 is provided with a rotor hub 6, and multiple blades are installed on the rotor hub 6. The nacelle 7 is provided with a transmission component that is connected to the rotor hub 6. For example, the rotor hub 6 can be connected to the transmission component in the nacelle 7 through the rotor rotation shaft. The nacelle 7 is directly scaled down from the fuselage 1 as a whole. Based on the parallel design principle, the tilt angle of the side of the nacelle 7 is consistent with the tilt angle of the hypotenuse of the inverted trapezoidal cross section of the fuselage 1. The tail of the nacelle 7 is a beveled structure, that is, it is beveled to form a straight tail beveled profile 16.

[0024] In some specific examples, three blades are evenly distributed on each hub 6, meaning the blades are evenly spaced along the circumference of the hub 6. The blades are connected to the hub 6 via a hinged connection, but this is not limited to hinged connections.

[0025] Based on the above implementation method, the outer contour of the nacelle 7 can be composed of multiple swept surfaces.

[0026] Specifically, from a side view, the outer contour of nacelle 7 includes an upper nacelle contour 13 and a lower nacelle contour 15. The upper nacelle contour 13 and the lower nacelle contour 15 are the upper and lower contours of the side of nacelle 7, respectively. The upper nacelle contour 13 is directly scaled from the fuselage contour 11, and the lower nacelle contour 15 is directly scaled from the fuselage lower contour 12. The tail of nacelle 7 has a beveled structure, forming the tail beveled contour 16 of the side profile of nacelle 7. From a top view, the outer contour of nacelle 7 includes two side contours 14. The side contours 14 are directly scaled from the spindle-shaped upper surface contour 9. From a front view, the outer perimeter contour of nacelle 7 is hexagonal. The top and bottom edges of the outer perimeter contour are parallel to the horizontal plane, and the angles formed by the other four beveled edges and the horizontal plane are the same as the angle A, that is, the same as the angle with the side of fuselage 1.

[0027] In some specific examples, the upper nacelle profile 13 is directly scaled from the fuselage profile 11 by a factor of 0.5; the lower nacelle profile 15 is directly scaled from the lower fuselage profile 12 by a factor of 0.5; and the side profile 14 is directly scaled from the spindle-shaped upper surface profile 9 by a factor of 0.5. In other specific examples, other scaling ratios may be used depending on the application.

[0028] To comprehensively suppress radar cross-section and aerodynamic noise in the blade design, one embodiment includes a blade tip 4 with an anhedral and swept-back structure. Based on this embodiment, by optimizing the anhedral and swept-back angles of the blade tip 4 and its initial position, the radar cross-section and aerodynamic noise of the tiltrotor are synergistically suppressed. In some specific examples, the anhedral angle of the blade tip 4 is 9.2°, and the swept-back angle is 11.7°, such as... Figure 10 and 11 This invention is implemented according to these two angle values, namely D=11.7° and E=9.2°. It should be noted that the backward folding angle of the 1 / 4 chord line of the blade tip 4 relative to the 5 1 / 4 chord line of the inner section of the blade is the sweep angle of the blade tip 4, with a value of D; the downward folding angle is the dihedral angle of the blade tip 4, with a value of E. Based on this example, as... Figure 1 As shown, the blade is divided into a tip 4 and an inner section 5. The inner section 5 is connected to the hub 6. The tip 4 is connected to the end of the inner section 5 away from the hub 6. The distribution range of the tip 4 on the blade is from 0.89R to 1.0R, where R is the radius of the blade. That is, the blade only performs downward and backward dipping of the tip 4 within the range of 0.89R to 1.0R.

[0029] In one embodiment, the fuselage 1 is connected to two symmetrically distributed wings 2 and two symmetrically distributed tail fins 3. In order to balance radar cross section suppression and aerodynamic efficiency, the wings 2 are forward-swept wings 2, and the tail fins 3 are upward-sweeping V-shaped tail fins 3. Based on the parallel design principle, the forward sweep angle of the wings 2 and the backward sweep angle of the tail fins 3 are the same.

[0030] It should be noted that the angle between the rearward view profile of the tail edge of tail fin 3 and the horizontal plane is the dihedral angle of tail fin 3; the angle between the top view profile of the tail edge of wing 2 and a straight line perpendicular to the plane of symmetry of fuselage 1 is the forward sweep angle of wing 2; and the angle between the top view profile of the leading edge of tail fin 3 and a straight line perpendicular to the plane of symmetry of fuselage 1 is the backward sweep angle of tail fin 3. In some specific examples, the dihedral angle of tail fin 3 is 30.2°. Figure 5 The letter B indicates that the forward sweep angle of wing 2 and the backward sweep angle of tail 3 are both 6.7°, and both are indicated by... Figure 6 The C in the middle represents...

[0031] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0032] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0033] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A tiltrotor aircraft, characterized in that, The fuselage has an overall spindle-shaped profile and an inverted trapezoidal cross-section. The outer peripheral surface of the fuselage includes an upper surface, a lower surface, and two side surfaces. The two side surfaces are connected between the upper surface and the lower surface and are located on both sides of the fuselage. The upper surface, the lower surface, and the two side surfaces are all composed of complete swept surfaces, and each swept surface is formed by sweeping straight lines.

2. The tiltrotor aircraft according to claim 1, characterized in that, The fuselage, viewed from above, has a spindle-shaped outline and includes a straight nose, a straight tail, and a spindle-shaped upper surface outline. The upper surface of the fuselage is formed by the straight nose sweeping along the spindle-shaped upper surface outline to the straight tail.

3. The tiltrotor aircraft according to claim 2, characterized in that, The fuselage, viewed from the front, has an inverted trapezoidal outline. The two sides of the fuselage form an angle A with the horizontal plane. The sides are formed by a straight line with an angle A with the horizontal plane sweeping along the upper surface outline of the spindle shape from the straight nose to the straight tail.

4. The tiltrotor aircraft according to claim 3, characterized in that, The outline of the fuselage, viewed from the side, is formed by the upper outline and the lower outline of the fuselage. The upper outline and the lower outline of the fuselage are the upper and lower outlines of the side of the fuselage, respectively, and both the upper outline and the lower outline of the fuselage are spline shapes.

5. The tiltrotor aircraft according to claim 4, characterized in that, The fuselage is connected to two symmetrically distributed wings. The ends of the wings away from the fuselage are connected to nacelles. The front end of the nacelle is provided with a rotor hub, and multiple rotor blades are installed on the rotor hub. The nacelle is provided with a transmission component that is driven by the rotor hub. The nacelle is directly scaled down from the fuselage as a whole, and the tail of the nacelle has a slanted structure.

6. The tiltrotor aircraft according to claim 5, characterized in that, From a side view, the outer contour of the nacelle includes an upper nacelle contour and a lower nacelle contour. The upper nacelle contour and the lower nacelle contour are respectively the upper and lower contours of the side of the nacelle. The upper nacelle contour is directly scaled from the upper contour of the fuselage, and the lower nacelle contour is directly scaled from the lower contour of the fuselage. The tail of the nacelle has a beveled structure and forms the tail beveled contour of the side profile of the nacelle. From a top view, the outer contour of the nacelle includes two side contours, which are directly scaled from the fusiform upper surface contour. From a forward view, the outer perimeter of the nacelle is hexagonal, with the top and bottom edges of the outer perimeter parallel to the horizontal plane, and the angles formed by the other four hypotenuses and the horizontal plane being the same as the included angle A.

7. The tiltrotor aircraft according to claim 5, characterized in that, The blade is provided with a blade tip, which has a downward and swept-back structure.

8. The tiltrotor aircraft according to claim 7, characterized in that, The dihedral angle of the propeller tip is 9.2°, the sweep angle of the propeller tip is 11.7°, and the distribution range of the propeller tip on the propeller blade is from 0.89R to 1.0R, where R is the radius of the propeller blade.

9. The tiltrotor aircraft according to claim 1, characterized in that, The fuselage is connected to two symmetrically distributed wings and two symmetrically distributed tail fins. The wings are forward-swept wings, and the tail fins are inverted V-shaped tail fins. The forward sweep angle of the wings and the backward sweep angle of the tail fins are the same.

10. The tiltrotor aircraft according to claim 9, characterized in that, The dihedral angle of the tail fin is 30.2°, and the forward sweep angle of the wing and the backward sweep angle of the tail fin are both 6.7°.

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