Helicopter, helicopter kit and related reconfiguration method

Abstract

The helicopter (1) comprises a fuselage (2) elongated along a first axis (X) and extending between a nose (6) and a tail boom (7), and a horizontal stabilizer (9) having a pair of first aerodynamic surfaces (11) elongated along a second axis (Y), the first and second axes defining a first plane (Q). The helicopter also comprises a pair of elements (20) transverse to the first aerodynamic surfaces and connected to the first elements, directing respective second aerodynamic forces toward and away from the first aerodynamic surfaces. and a pair of spaced apart second aerodynamic surfaces (21), each having a first base end (80) connected to a respective one of the elements, a second free end (81) spaced from the tail boom, a first leading edge (55), a first trailing edge (56) opposite the first leading edge, a first chord (C1) at the first base end, and a second chord (C2) at the second free end parallel to the first axis, the first and second chords defining a second plane (R) inclined with respect to the first plane.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application No. 20164164.4, filed March 19, 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0002] Technical Field The present invention relates to a helicopter, a helicopter kit and a helicopter reconfiguration method. [Background technology]

[0003] A helicopter, in a known manner, comprises an airframe, a main rotor extending from the airframe and rotatable about a first axis, and a tail rotor extending from the airframe and rotatable about a second axis transverse to the first axis.

[0004] In particular, the main rotor is configured to provide the lift necessary to keep the helicopter airborne and to enable forward, reverse and lateral movement of the helicopter, while the tail rotor is configured to counteract rotation of the helicopter caused by reaction torques transferred to the airframe by operation of the main rotor and to control the yaw, i.e., rotation of the helicopter about a first axis.

[0005] The helicopter may also be - nose and tail booms disposed separately at both ends of the aircraft; a fin extending upward from the tail boom of the aircraft in a cantilevered manner and supporting the tail rotor in a rotatable manner about a second axis; - a horizontal stabilizer, known as a pitch stabilizer, which projects laterally relative to the aircraft body in a cantilevered manner from the tail boom; Equipped with.

[0006] The horizontal stabilizer is configured as a wing profile having a major component oriented parallel to the first axis when the helicopter is in forward flight. Generates the first aerodynamic force, i.e. lift / negative lift.

[0007] Such lift / negative lift, in addition to the lift generated by the main rotor, is effective in maintaining the altitude of the helicopter in a stable state during high speed forward flight, i.e. in ensuring that the helicopter is in a stable equilibrium position with respect to rotation vertically and about its third longitudinal axis, in particular the third axis being parallel to the extension of the fuselage oriented from the nose to the tail boom and transverse to the first and second axes.

[0008] However, at certain low speed conditions, the airflow directed downward by the main rotor can be deflected towards the tail of the aircraft, where it strikes the horizontal stabilizer and thus generates a tertiary aerodynamic force, i.e., downward thrust on the horizontal stabilizer.

[0009] Following acceleration and / or deceleration of the helicopter, this vertical causes the helicopter to assume a nose-up attitude, i.e., the nose of the aircraft is higher than the tail of the aircraft. This nose-up attitude must be continually corrected by the pilot's action on the cyclic pitch of the main rotor, i.e., by tilting the main rotor disks forward to move the airflow away from the horizontal stabilizer.

[0010] This can make flight control difficult for the pilot in certain low speed conditions.

[0011] Furthermore, a nose-up attitude during the landing phase creates visual problems for the pilot, which can become more problematic in the case of gusts of wind, bad weather or when obstacles are present in the landing area.

[0012] For these reasons, the design of the horizontal stabilizer must satisfy two conflicting constraints.

[0013] In more detail, on the one hand, a large horizontal stabilizer surface is required to generate an adequate value for the first aerodynamic force and thus increase the longitudinal stability of the helicopter.

[0014] On the other hand, a small horizontal stabilizer surface is optimal at low speeds to reduce the surface exposed to the downdraft generated by the main rotor and the amount of resulting nose-up of the helicopter, thus improving the visibility and controllability of the helicopter in unique critical situations such as landing.

[0015] Due to these constraints, various horizontal stabilizer configurations have been used in helicopters since the 1950s, but have not provided an optimal solution, such as the known asymmetric horizontal stabilizer located only on one side of the fuselage and at different heights relative to the tail boom, and the symmetric solution with two stabilizers located at different heights and different longitudinal positions relative to the fuselage.

[0016] No. 5,399,633 describes a helicopter equipped with a horizontal stabilizer, the horizontal stabilizer comprising: a pair of stabilizers extending in a cantilevered manner from each side of the tail boom; a pair of aerodynamic appendages extending in a cantilevered manner from each side of the aircraft, interposed between the respective stabilizers; a pair of end plates opposite each side and extending between each of the stabilizers and each of the other appendages; Equipped with.

[0017] When a helicopter is in high speed forward flight, the aerodynamic wash generated by the airframe and main rotor causes significant disruption of the airflow which impinges on some of the appendages following the airframe.

[0018] As a result, these sections are in the aerodynamic "shadow" and do not contribute effectively to the generation of the secondary aerodynamic forces necessary to longitudinally stabilize the helicopter.

[0019] Thus, the industry has recognized a need to optimize the aerodynamic behavior of the horizontal stabilizer to increase the longitudinal stability of the helicopter in forward flight while at the same time limiting nose-up at low speed conditions.

[0020] Additionally, the industry has recognized a need to optimize the aerodynamic behavior of horizontal stabilizers and fins with respect to angle of attack characteristics during forward flight, side flight and low speed phases of landing / takeoff to limit or even avoid maximum aerodynamic forces occurring at angles of attack characteristic of increased dimensions and / or stall.

[0021] More particularly, the industry is well aware of the need to have available a horizontal stabilizer that can reduce as much as possible the effects of the underdraft generated by the main rotor at low speeds.

[0022] The industry is well aware of the need to have available horizontal stabilizers which can improve the aerodynamic efficiency of the horizontal stabilizer as much as possible.

[0023] Patent document 2 discloses a helicopter according to the preamble of claim 1, a kit for a helicopter according to the preamble of claim 12 and a reconfiguration method for a helicopter according to the preamble of claim 15. [Prior art documents] [Patent documents]

[0024] [Patent Document 1] U.S. Patent No. 8,985,500 [Patent Document 2] European Patent Application Publication No. 2878536 Summary of the Invention [Problem to be solved by the invention]

[0025] The object of the present invention is to create a helicopter that is able to satisfy at least one of the above-mentioned needs in a simple and inexpensive manner. [Means for solving the problem]

[0026] According to the invention, this object is achieved by a helicopter according to claim 1.

[0027] The invention likewise relates to a kit for a helicopter according to claim 12.

[0028] The invention likewise relates to a method for reconfiguring a helicopter according to claim 15.

[0029] In order that the invention may be better understood, preferred, non-limiting embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0030] [Figure 1] 1 is a perspective view of a helicopter formed in accordance with the present invention; [Diagram 2] FIG. 2 is a highly enlarged view, with parts removed for clarity, of the tail section of the helicopter of FIG. 1 from above; [Diagram 3] FIG. 3 is a highly enlarged perspective view, with parts removed for clarity, of the tail section of the helicopter of FIGS. 1 and 2; [Figure 4] FIG. 4 is a highly enlarged top view of the helicopter of FIGS. 1 to 3 in detail; [Diagram 5] FIG. 5 is a front view showing details of the helicopter of FIG. 4. [Figure 6] FIG. 6 is a perspective view showing details of FIGS. 4 and 5. [Figure 7] FIG. 7 is a side view showing a detail of FIGS. 4 to 6. [Figure 8] FIG. 8 is a further enlarged view showing some details of FIGS. 4 to 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] With reference to the accompanying drawings, the reference numeral 1 indicates a helicopter formed in accordance with the teachings of the present invention.

[0032] The helicopter 1 basically comprises a fuselage 2, a main rotor 3 arranged on top of the fuselage 2, and a tail rotor 5.

[0033] The aircraft 2 comprises a nose boom 6 and a tail boom 7 at either end of the aircraft.

[0034] What can be specified is: a roll axis X corresponding to the longitudinal direction of the helicopter 1 and the fuselage 2, - a pitch axis Y perpendicular to the axis X; and -Yaw axis Z perpendicular to axes X and Y; It is.

[0035] The axes X, Y, Z are integral with the helicopter 1 and indicate its centre of gravity G (not shown in its exact position in the accompanying drawings for ease of illustration).

[0036] Similarly, it can be stipulated that - a plane P perpendicular to the axis Y and parallel to the axes X and Z, and - a plane Q perpendicular to the axis Z and parallel to the axes X and Y, It is.

[0037] In particular, plane P is a longitudinal plane of helicopter 1 and plane Q is a transverse plane of helicopter 1 .

[0038] It should be noted that in the remainder of this description, the terms "upward", "downward", "sideways", "forward", "rearward" etc. are used in reference to the normal forward direction of the helicopter in forward flight at constant altitude, i.e. with axis Z vertical and axes X, Y horizontal.

[0039] The main rotor 3 is configured to provide a thrust force having a main component parallel to axis Z, thereby enabling the helicopter 1 to be kept in the air and to have both forward and reverse movement parallel to axis X and lateral movement parallel to axis Y.

[0040] The tail rotor 5 is configured to provide a thrust force having a principal component parallel to axis Y. This thrust force generates a torque about axis Z in a direction opposite to the reaction torque acting on the airframe 2 following operation of the main rotor 3, thereby controlling the yaw angle of the helicopter 1.

[0041] The nose boom 6 and the tail boom 7 are opposite each other along the longitudinal axis X of the helicopter 1 .

[0042] Helicopter 1, likewise, a fin 8 projecting in a cantilever manner from the top of the tail boom 7 at the end opposite the nose 6; a horizontal stabilizer 9 projecting in a cantilever manner from the tail boom 7 below the fin 8 and adapted to stabilize the helicopter 1 in the longitudinal direction, i.e. along the axis X; Equipped with.

[0043] The fins 8 support the tail rotor 5 .

[0044] The horizontal stabilizer 9 is configured to generate an aerodynamic force having a main component parallel to the axis Z, thereby stabilizing the helicopter 1 longitudinally during forward flight, i.e. stabilizing the altitude of the helicopter 1 against rotation about the axis Y.

[0045] In more detail, the horizontal stabilizer 9 includes a pair of stabilizers 14 disposed on opposite sides of the tail boom 7 .

[0046] In the following description, reference will be made to only one of the stabilizers 14 since they are identical to each other.

[0047] The stabilizer 14 has a length parallel to the axis Y, a width parallel to the axis Y, and a thickness parallel to the axis Z.

[0048] The stabilizer 14 comprises a load-bearing surface 11 which is configured to generate a lift / negative lift force having a main component parallel to the axis Z.

[0049] The surface 11 of the stabilizer 14, in turn, a front edge 15 facing the nose 6 and defining a first frontmost edge of the stabilizer 14; a rear edge 16, which is opposite the front edge 15 along the axis X and which defines a second rearmost edge of the stabilizer 14; a top surface 17 defined between the leading edge 15 and the trailing edge 16 and defining the upper surface of the stabilizer 14; a bottom surface 18 defined between the leading edge 15 and the trailing edge 16, opposite the top surface 17, and defining the lower surface of the stabilizer 14; It is divided by.

[0050] The surface 11 likewise comprises a pair of edges 12a, 12b opposite each other and parallel to the axis Y. The edges 12a of each of the surfaces 11 are fixed to the tail boom 7.

[0051] The surface 11 has a chord B (FIGS. 3 and 4) that connects a leading edge 15 and a trailing edge 16 in a straight path parallel to the axis X.

[0052] The length of the chord B is constant.

[0053] Advantageously, the stabilizer 14 comprises: a plate 20 projecting in a cantilevered manner in a transverse direction relative to the surface 11; - a second aerodynamic force generating appendage 21 connected to the plate 20 and facing the surface 11 at a predetermined distance; The attachment 21, in turn, comprises: a proximal end 80 connected to the plate 20; a free end 81 spaced apart from the tail boom 7 and from the fin 8 and opposite the base end 80; a leading edge 55; a trailing edge 56 opposite the leading edge 55; a chord C1 (FIGS. 2, 6 and 7) parallel to the axis X and connecting in a straight line at its free end 81 the leading edge 55 and the trailing edge 56; a chord C2 parallel to the axis X and joining the leading edge 55 and the trailing edge 56 at the base end 80 in a straight line; Equipped with The chords C1, C2 define a plane R inclined relative to the plane Q (FIG. 5).

[0054] More specifically, the plane R is tilted with respect to the plane Q at a non-zero angle α ranging between 0° and 30°, more specifically between 0° and 15° (FIG. 5).

[0055] This therefore allows desirable control of the distance between surface 11 and appendage 21, minimizing adverse effects due to mutual interference between the surfaces.

[0056] An appendage 21 extends further from the plate 20 towards the body of the helicopter 1 .

[0057] Appendages 21 extend further from plate 20 at progressively increasing distances from surface 11 .

[0058] That is, the appendages 21 converge towards each other from their respective plates 20 to the sides opposite their respective surfaces 11 (FIG. 2).

[0059] In the illustrated case, chord C1 is shorter than chord C2.

[0060] More specifically, the length of the chord C of the appendage 21 decreases from chord C2 to chord C1 (FIG. 2).

[0061] The appendage 21 further has a swept wing.

[0062] More specifically, the chord C1 has a section C3 which protrudes from the surface 11 in a plan view from above the helicopter 1.

[0063] Similarly, the chord C2 has a section C4 which projects from the surface 11 in a plane viewed from above the helicopter 1 (FIG. 4).

[0064] The length of each of the sections C3, C4 parallel to the axis X ranges between −50% and +50% of the chord B of the surface 11.

[0065] The length of each of sections C3, C4 has a positive value if, in a plane viewed from above the helicopter 1, section C3 projects from the leading edge 15 of surface 11 towards the nose 6.

[0066] Conversely, the length of each of sections C3, C4 has a negative value when, in a plane viewed from above the helicopter 1, sections C3, C4 protrude from the trailing edge 16 of surface 11 towards the tail boom 7.

[0067] In the case shown, sections C3, C4 project from the leading edge 15 of the surface 11 towards the nose 6 of the helicopter 1.

[0068] Section C4 is similarly shorter than section C3.

[0069] As a result, the appendages 21 have a negative swept back and are staggered towards the nose 6 with respect to the surface 11 .

[0070] More specifically, an aerodynamic surface has a negative swept back when the aerodynamic surface has a forward position (i.e., oriented toward the nose portion 6) at a position corresponding to 1 / 4 of the chord at the free end relative to the same position corresponding to 1 / 4 of the chord at each alternate base end portion (i.e., oriented aft or opposite the fin 8).

[0071] In particular, the leading edge 55 defines a first edge which is directed towards the nose 6 and which is forward of the appendage 21 with respect to the general forward direction of the helicopter 1 .

[0072] The trailing edge 56 is opposite the leading edge 55 along the axis X, the trailing edge being directed away from the nose 6 and defining a second edge that is rearward of the appendage 21 with respect to the generally forward direction of the helicopter 1.

[0073] Appendix 21 similarly states: a top surface 57 defined between a leading edge 55 and a trailing edge 56 and defining the upper surface of the appendage 21; a bottom surface 58 defined between the front edge 55 and the rear edge 56 opposite the top surface 57 and defining the underside of the appendage 21; Equipped with.

[0074] A plate 20 is opposite the fin 8 along the axis Y, the plate being connected to the surface 11 and projecting upwardly from an edge 12b of the surface 11 in a cantilevered manner.

[0075] More specifically, the plate 20 is bounded parallel to the axis Z by an edge 30 connected to the edge 12 b of the surface 11 and by an edge 31 opposite the edge 30 .

[0076] 2 and 3, the appendage 21 and the plate 20 are connected by a sharp edge. In particular, the edge 31 and the base end 80 coincide with each other.

[0077] The edges 30, 31 extend parallel to the axis X.

[0078] The edge 31 is disposed over the edge 30 and the appendage 21 is connected to the edge.

[0079] In particular, edge 31 is more distal than edge 30. Edge 30 is thus interposed between edges 31 along axis Y.

[0080] Plate 20 similarly shows a front edge 48 facing the nose 6 and defining a first frontmost edge of the plate 20; a rear edge 49 located opposite the front edge 48 along the axis X and defining a second rearmost edge of the plate 20; a wall 51 defined between the leading edge 48 and the trailing edge 49 and defining a surface directed towards the fins 8 of the plate 20; a wall 52 defined between the leading edge 48 and the trailing edge 49 opposite the wall 59 and defining the surface of the plate 51 opposite the fin 8; It is divided by.

[0081] The plate 20 likewise comprises a number of chords D, each of which extends in a straight manner between a leading edge 55 and a trailing edge 56 (FIG. 6).

[0082] The chords D1, D2 of the plate 20 at the edges 30, 31 define a plane S.

[0083] In the illustrated case, the plane S is orthogonal to the plane R, as shown by way of example in FIG. 5 attached.

[0084] More specifically, the plane S defines an angle β with the axis Z (FIG. 5) lying in the range between −30° and 30°, more preferably lying in the range between −20° and 20°. Thus, the connection between the plate 20 and the appendage 21 can be controlled as desired, minimizing the adverse effects of mutual interference between the surfaces.

[0085] The angle β is oriented so as to have a positive result when the planes S diverge from one another about the axis Z, and a negative result when the planes converge from one another about the axis Z.

[0086] In the illustrated case, the planes S diverge from one another about the axis Z as they progress from the surface 11 towards the corresponding appendages 21 (FIG. 5).

[0087] The plane S likewise defines an angle γ with the axis X that lies in the range between −15° and 15°, more preferably in the range between −10° and 10° (FIG. 4).

[0088] For this reason it is possible to modify the pressure field occurring in the elements 11 , 20 , 21 , in particular the local dips, and therefore to obtain greater efficiency values ​​than for the horizontal stabilizer 9 as a whole.

[0089] The angle γ is oriented to have a positive / negative effect when the planes S converge / diverge from each other about the axis X as one progresses from the fin 8 towards the nose 6 .

[0090] In the case shown, the planes S likewise converge with respect to the axis X as one progresses from the fin 8 towards the nose 6 (FIG. 4).

[0091] As plate 20 advances from edge 30 toward edge 31 (FIG. 7), a portion 90 spaced apart from the edge 31, along which the length of the chord D is constant and equal to the value D1; a portion 91 spaced apart from the edge 30, along which the length of the chord D decreases from a value D1 to a value D2; Equipped with.

[0092] Each horizontal stabilizer 9 comprises an additional element 100 which projects in a cantilevered manner 12b from the respective surface 11 on the opposite side of the respective plate 20. The plate 20 is disposed below the surface 11 (FIG. 5).

[0093] Each of the elements 100 includes, inter alia: a base end 101 connected to the edge 12b of each respective surface 11 and to the edge 30 of each respective plate 20; a free end 102 opposite the base end 101; Equipped with.

[0094] Each of the further elements 100 similarly comprises: a front edge 111 defining a first edge oriented towards the nose 6 and forward of the plate 20; a rear edge 112 defining a second edge opposite the front edge 111 along the axis X and rearward of the plate 20; Equipped with.

[0095] Each of the elements 100 likewise comprises a number of chords E, each of which extends in a linear manner between a leading edge 111 and a trailing edge 112 .

[0096] The length of the chord E at the base end 101 is designated E1.

[0097] The chord E is said to decrease in value from the base end 101 to the free end 102 (FIG. 6).

[0098] The chord E defines a plane T (FIG. 5).

[0099] Plane T is parallel to plane P and perpendicular to plane Q in the illustrated case.

[0100] The distance between the chord E1 and the free end 102 along the plane T is less than the length between the chords D1, D2 along the plane S in the case shown.

[0101] Referring to FIG. 3, each surface 11 similarly includes a pair of flaps 50, also known as Gurney flaps, attached respectively to either side of a respective trailing edge 56, lying in the same plane and both perpendicular to the trailing edge 56, thereby forming a T-shape.

[0102] Each surface 11 in particular comprises an area 53 adjacent to the plate 20 parallel to the axis Y and interposed between a section 106 of the leading edge 15 and a corresponding section 107 of the trailing edge 16 parallel to the axis X (Figures 2 and 4).

[0103] More specifically, each of the regions 53 defines an extension of a respective one of the surfaces 11 .

[0104] In particular, the leading edge, trailing edge, top surface and bottom surface of each of the regions 53 are extensions of the leading edge 15 , trailing edge 16 , top surface 17 and bottom surface 18 of each of the separate surfaces 11 .

[0105] In the illustrated case, the wing span 60 , ie the extension parallel to the Y-axis of the region 53 , ranges between about 5% and about 35% of the wing span 61 of the appendage 21 .

[0106] 5, the distance between chords D1, D2 measured in plane S - i.e. the "height" of plate 20 - lies in the range between 10% and 100% of the chord B of surface 11.

[0107] 6 and 7, it is possible to identify a chord E2 disposed closer to the base end 101, towards the free end 102, and having a length less than the chord E1. The chord E2 is disposed parallel to the chord E1.

[0108] The length of the chord E tapers from a length of chord E1 to a length of chord E2.

[0109] The distance between the chords E1, E2 measured in the plane T - i.e. the height of the element 100 - lies in the range between 10% and 100% of the length of the chord B of the surface 11.

[0110] The length of chord C2 lies in the range between 20% and 100% of the length of chord B of surface 11.

[0111] The length of chord C1 ranges between 20% and 100% of the length of chord C2.

[0112] Alternatively, as shown in FIGS. 1 and 4-8, the stabilizer 14 includes a connecting portion 120 interposed between the proximal end 80 of the appendage 21 and the edge 31 of the plate 20. As shown in FIG.

[0113] Portion 120 extends from edge 31 towards end 80 at a distance that increases from surface 11 and decreases from fin 8 .

[0114] The chord length of portion 120 tapers from a value D2 to a value C2.

[0115] The plate 20, the appendage 21, the area 53 of the stabilizer 14 and the Gurney flap 50 form a reconstruction kit 85 (FIG. 2) for a helicopter stabilizer having only the surface 11.

[0116] The operation of the helicopter 1 is mainly described starting from slow forward flight or hovering, for example during the take-off / landing phase.

[0117] In this condition, the counter torque about the Z axis generated on the fuselage 2 by the operation of the main rotor 3 is approximately balanced by the tail rotor 5. In practice, due to the low or zero speed of the helicopter 1, the aerodynamic forces generated by the fins 8 are negligible.

[0118] Furthermore, in this state, the downward wash from the main rotor 3 toward the tail boom 7 collides with the stabilizer 14 of the horizontal stabilizer 9 .

[0119] The appendages 21 arranged above the surfaces 11 obstruct the passage of this wash towards the surfaces 11 , so that these surfaces experience a particularly small or zero downward thrust due to the wash of the main rotor 3 .

[0120] Furthermore, the small overall extension of the appendage 21 allows the downward thrust exerted by this wash on the horizontal stabilizer 9 to be further reduced.

[0121] As a result, it reduces the nose-up moment generated by this thrust about axis Y, and therefore reduces the altitude variations of the helicopter 1 and the corrections required by the pilot during the takeoff / landing phases.

[0122] Moreover, in these conditions, the horizontal stabilizer 9 generates an aerodynamic thrust having a component parallel to the axis Z, which aerodynamic thrust is capable of maintaining the helicopter 1 in a stable equilibrium with respect to translation along the axis Z and rotation about the axis Y.

[0123] The presence of the aircraft 2 prevents the aerodynamic flow from impinging on the horizontal stabilizer 9 .

[0124] The kit 85 is used to reconstruct helicopters with stabilizers, which only comprise the surface 11 without the respective separate regions 53 .

[0125] More specifically, region 53 of kit 85 is disposed adjacent to and connected to each respective surface 11 along axis Y, thereby defining a respective extension of the respective surface, whereby each respective appendage 21 has a respective free end 81 oriented a predetermined distance from each respective surface 11 and spaced apart from the tail boom 7 / fin 8 along axis Y.

[0126] From examining the characteristics of the helicopter 1, the kit 85 and the method according to the invention, the advantages which can be realised therefrom are clear.

[0127] In particular, the appendages 21 of the stabilizer 14 generate aerodynamic forces and have separate free ends 81 spaced apart from the tail boom 7 / fin 8 and separate planes R inclined at an angle α with respect to the plane Q.

[0128] In this way, at high speeds, the lift / negative lift generated by the appendage 21 along the axis Z is added to the lift / negative lift generated by the surface 11 and on the other hand contributes as a dominant effect to increasing the longitudinal stability of the helicopter 1.

[0129] On the other hand, because the appendages 21 are spaced apart from the fins 8, the stabilizer 14 is less heavy and bulky than the stabilizers in the known solutions described in the introductory part of the present description, which has clear advantages with respect to the helicopter 1.

[0130] This weight reduction is obtained without any penalty regarding the aerodynamic forces generated by the stabilizer 14, since the fuselage 2 and the main rotor 3 sufficiently obstruct the airflow reaching the area interposed between the appendage 21 and the fins 8, making the generation of aerodynamic forces in this area rather inefficient.

[0131] That is, the horizontal stabilizer 9 reduces weight and provides high longitudinal stability for the helicopter 1 .

[0132] At low speeds, surface 11 is in the turbulent wash of the appendages 21. Thus, the downward thrust on the horizontal stabilizer 9 generated by the wash of the main rotor 3 is reduced with respect to conventional solutions, reducing the tendency of the helicopter 1 to adopt a nose-up attitude and improving pilot comfort and visibility during landing maneuvers.

[0133] The applicant has observed that due to the fact that the appendages 21 each have a free end 81, the downward thrust generated by the rotor flow on the horizontal stabilizer 9 can be further reduced. The presence of the free end 81 likewise makes it possible to substantially reduce the overall reduced drag on the horizontal stabilizer 9, thus improving the aerodynamic efficiency of the horizontal stabilizer.

[0134] In summary, what the applicant has observed is that the introduction of appendage 21 can increase the lift slope of the lift coefficient with respect to the angle of attack, thereby reducing the increase in maximum lift at the stall condition.

[0135] Since the angle of attack of the horizontal stabilizer 9 corresponding to normal flight conditions of the helicopter 1 - forward flight, side flight, hovering, low speed flight during takeoff / landing - is less than the stall angle of attack, the appendage 21 can increase the value of the aerodynamic force generated by the horizontal stabilizer 9 at angles of attack typical for the operation of the helicopter 1.

[0136] The plane S defines an angle β with the axis Z that lies in the range between −30° and +30°, preferably in the range between −20° and +20°.

[0137] Thus, the bond between the plate 20 and the appendage 21 can be controlled as desired, minimizing adverse effects due to mutual interference between the surfaces.

[0138] The plane S likewise defines an angle γ with the axis X ranging between −15° and 15°, preferably ranging between −10° and 10°.

[0139] It is therefore possible to modify the pressure field, and in particular the local depression, occurring on the elements 11, 20, 21 and to obtain the desired efficiency values ​​greater than those of the horizontal stabilizer 9. The sections C3, C4 of each appendage 21 have a length parallel to the axis X ranging between -50% and 50% of the chord C of the respective surface 11.

[0140] Due to that, the appendages 21 have swept-back wings and are staggered with respect to each other surface 11 along the axis X. It is thus possible to control the interaction between the downward airflows generated by the rotor 3 and the horizontal stabilizer 9 during low speed flight conditions, in particular in the tail, by arranging the appendages 21 on the surface 11.

[0141] The flap 50 attached perpendicularly to the trailing edge 56 of the surface 11 allows to increase the aerodynamic force generated by the horizontal stabilizer 9 for a small increase in aerodynamic resistance. In particular, due to the T-shaped flap 50 and the T-shaped respective trailing edge 56, it is possible to increase the lift / negative lift and the relative maximum value of the lift coefficient generated by the surface 11 as the angle of attack changes.

[0142] The kit 85 makes it possible to reconstruct a helicopter having a traditional horizontal stabilizer by simply fastening the area 53 to the surface 11, thereby defining its extension and positioning the appendage 21 facing the surface 11 and spaced from the tail boom 7 / fin 8.

[0143] Because the appendage 21 is spaced from the tail boom 7 / fin 8 , application of the kit 85 does not require any action on the tail boom 7 , greatly simplifying reconfiguration of the helicopter 1 .

[0144] The T-shaped flap 50 is particularly advantageous when it is integrated into the kit 85. Indeed, the T-shape makes it possible to increase the lift generated by the stabilizer 14 without modifying the altitude of the helicopter 1 with respect to the situation in which the kit 85 is not present.

[0145] What is clear is that modifications and variations may be made to the helicopter 1, kit 85 and method described herein without departing from the scope thereof as defined in the claims.

[0146] In particular, each stabilizer 14 may include at least one additional first appendage 21 arranged on a side of the top surface 17 of the surface 11 along axis Z and spaced apart from the fin 8 along axis Y, and at least one additional second appendage 21 arranged on a side of the bottom surface 18 of the surface 11 along axis Z and spaced apart from the tail boom 7 along axis Y.

[0147] In particular, the additional first appendage 21 may be more than one and / or the additional second appendage 21 may be more than one.

[0148] Alternatively, each stabilizer 14 may include at least two additional first appendages 21 disposed on a side of the top surface 17 of the surface 11, spaced apart from the fins 8 and staggered from the axis X. Alternatively, each stabilizer 14 may include at least two additional second appendages 21 disposed on a side of the bottom surface 18 of the surface 11, spaced apart from the fins 8 and staggered along the axis X.

[0149] The additional first and second appendages 21 make it possible to increase the aerodynamic forces generated by the horizontal stabilizer 9 and thus the stabilizing effect at high speeds, and further increase the shielding effect of the surface 11 against the downward flow generated by the rotor 3.

[0150] Alternatively, the lengths of the sections C3, C4 of each appendage 21 may be the same. In this case, each appendage 21 is simply staggered with respect to the respective surface 11 towards the nose 6 or tail boom 7.

[0151] The chords B, C, D, E of the surface 11, the appendage 21, the plate 20 and the element 100 may be curved, i.e. obtained by rotation through a certain angle in each of the separate planes R, S, T. In this case, the planes R; S, T specify the planes defined by the unbent chords C1, C2; D1, D2; E1, E2. [Explanation of symbols]

[0152] 1 helicopter, 2 fuselage, 3 main rotor, 5 tail rotor, 6 nose, 7 tail boom, 8 fin, 9 horizontal stabilizer, 11 first aerodynamic surface, load bearing surface, element, 12a, 12b edge, 14 stabilizer, 15 leading edge, 16 trailing edge, 17 top surface, 18 bottom surface, 20 plate, 21 element, 21 second aerodynamic surface, first appendage, second appendage, 30 first edge, third end, 31 second edge, fourth end, 48 leading edge, 49 trailing edge, 50 T-shaped flap, Gurney flap, 51 wall, plate, 52 wall, 53 area, 55 first leading edge, second leading edge, 56 first trailing edge, second trailing edge, 57 top surface, 58 bottom surface, 59 wall, 60, 61 span, 80 first base end, 81 second free end, 85 performance improvement kit, reconfiguration kit, 89 first base end, 90 section, 91 section, 100 second element, 101 third base end, 102 fourth free end, 106 first leading edge, section, 107 second trailing edge, section, 111 first aerodynamic surface, third leading edge, 112 third trailing edge, 120 connecting section, B chord, C fifth chord, C1 second chord, C1 first chord, C2 second chord, C2 value, C3 section, C4 section, D sixth chord, D1 third chord, D2 fourth chord, E chord, E1 seventh chord, E2 eighth chord, G centre of gravity, P plane, Q first plane, R second plane, S 1st plane, 2nd plane, 3rd plane, T 4th plane, flap, X 1st longitudinal axis, roll axis, Y 2nd axis, pitch axis, Z 3rd axis, yaw axis, α non-zero angle, β 3rd angle, γ 2nd angle

Claims

1. A helicopter (1), a body (2) elongated along a first longitudinal axis (X) of the helicopter (1) and extending between a nose (6) and a tail boom (7) of the helicopter (1), from which a fin (8) projects; a horizontal stabilizer (9) arranged on and transverse to said tail boom (7), said horizontal stabilizer (9) generating, in use, respective first aerodynamic forces and defining a pair of first aerodynamic surfaces (11) elongated along a second axis (Y) transverse to said first axis (X), said first and second axes (X, Y) defining a first plane (Q); a pair of first elements (20) connected to said horizontal stabilizer (9) and transverse to each respective one of said first aerodynamic surfaces (11); a pair of second aerodynamic surfaces (21) which generate respective second aerodynamic forces in use, the pair of second aerodynamic surfaces being connected to respective respective first elements (20), facing towards and spaced upwards from respective respective first aerodynamic surfaces (11); Equipped with Each of said second aerodynamic surfaces (21), in turn, - a first base end (80) connected to each of the separate pairs of said elements (20); a first front edge (55); a first rear edge (56) opposite said first front edge (55); a first chord (C2) parallel to said first axis (X) and joining said first leading edge (55) and said first trailing edge (56) at said first base end (80); a second chord (C1) parallel to said first axis (X) and joining said first leading edge (55) and said first trailing edge (56) at a second free end (81); Equipped with the first and second chords (C2, C1) define a second plane (R) inclined relative to the first plane (Q); each said second aerodynamic surface having a second free end (81) spaced from said tail boom (7) and opposite said first base end (80); said second chord (C1) being defined at said second free end.

2. A helicopter according to claim 1, characterized in that the first and second planes (Q, R) are inclined to each other at a non-zero angle (α) ranging between 0° and 30°.

3. Each of the first elements (20) a third end (30) connected to each separate said first aerodynamic surface (11); a fourth end (31) connected to each respective second aerodynamic surface (21) and opposite to said third end (30); a second front edge (55); a second trailing edge (56); a third chord (D1) parallel to said first axis (X) and joining said second leading edge (55) and said second trailing edge (56) at said third end (30); a fourth chord (D2) parallel to said first axis (X) and joining said second leading edge (55) and said second trailing edge (56) at said fourth end (31); Equipped with the third and fourth chords (D1, D2) define a third plane (S); 3. A helicopter according to claim 1 or 2, characterized in that the third plane (S) is inclined with respect to the first axis (X) at a second angle (γ) lying in the range between -15° and 15° and / or is inclined with respect to a third axis (Z) perpendicular to the first plane (Q) at a third angle (β) lying in the range between -30° and 30°.

4. 4. A helicopter according to any one of claims 1 to 3, characterized in that each of the second aerodynamic surfaces (21) has a respective fifth chord (C) parallel to the first axis (X) which gradually decreases in length as it progresses from a respective first element (20) towards a respective one of the free ends (81) and as it progresses from the first chord (C2) towards the second chord (C1).

5. 5. A helicopter according to claim 1, characterized in that the second aerodynamic surfaces (21) extend starting from each separate first element (20) and approaching each other above the first aerodynamic surfaces (11).

6. each said first element (20) comprises a respective separate portion (91) spaced from a respective separate first aerodynamic surface (111) and connected to a respective separate second aerodynamic surface (21); each of said portions (91) having a respective sixth chord (D) parallel to said first axis (X) which gradually decreases as it progresses towards a respective second aerodynamic surface (21); 6. A helicopter according to any one of claims 1 to 5, characterized in that the sixth chord (D) has a length equal to or greater than the second chord (C1) as it progresses towards each respective second aerodynamic surface (21).

7. 7. A helicopter according to any one of claims 1 to 6, characterized in that each of the second aerodynamic surfaces (21) starts from a respective one of the first elements (20) and extends towards the nose (6) of the helicopter (1) and protrudes from a leading edge (15) of the first aerodynamic surface (11) in a top view of the helicopter.

8. 8. A helicopter according to any one of claims 1 to 7, characterized in that each of the second aerodynamic surfaces (21) is tapered as it progresses from the first base end (80) towards the second free end (81).

9. 9. A helicopter according to any one of claims 3 to 8, characterized in that the third planes (S) extend starting from each respective first aerodynamic surface (11) and spaced apart from one another about a third axis (Z) perpendicular to the first axis (X) and the second axis (Y).

10. 10. A helicopter as claimed in any one of claims 3 to 9, characterized in that the third planes (S) extend closer to each other about the first axis (X) as they progress from the tail boom (7) towards the nose (6) of the helicopter (1).

11. A pair of second elements (100), Each of the second elements (100) is connected to each of the first aerodynamic surfaces (11) and to each of the first elements (20) at a respective third base end (101) and extends on an opposite side of each of the first elements (20) relative to each of the first aerodynamic surfaces (11); Each of the second elements (100) a fourth free end (102) opposite each of said third proximal ends (101); a third front edge (111), a third rear edge (112) opposite said third front edge; a seventh chord (E1) parallel to the first axis (X) at the third base end (101) connecting the third leading edge (111) and the third trailing edge (112); an eighth chord (E2) connecting said third leading edge (111) and said third trailing edge (112) parallel to said first axis (X) at said fourth free end (102); Equipped with 11. A helicopter according to any one of claims 3 to 10, characterized in that the seventh and eighth chords (E1, E2) define a fourth plane (T) inclined with respect to the third plane (S) and perpendicular to the first plane (Q).

12. A performance improvement kit (85) for a helicopter (1), comprising: an area (53) fixable to a first aerodynamic surface (11) defined by the horizontal stabilizer (9) of said helicopter (1), thereby defining an extension of said first aerodynamic surface along a first axis (Y); at least one element (20) transverse to said region (53), - a second aerodynamic surface (21) in a transverse direction to said first element (20), configured in use to generate an aerodynamic force and arranged above each of said regions (53) with respect to said first aerodynamic surface (11); Equipped with each of said regions (53) defining a first leading edge (106) and a second trailing edge (107) that are opposite each other in a direction transverse to said first axis (Y); the first axis (Y) and the second axis (X) define a first plane (Q); Each of said second aerodynamic surfaces (21) comprises: a first proximal end (80) connected to each separate said element (20); a second front edge (55); a second rear edge (56) opposite said second front edge (55); a first chord (C1) connecting said second leading edge (55) and said second trailing edge (56) parallel to said second axis (X) at a second free end (81); a second chord (C2) parallel to the first axis (X) at the first base end (80) connecting the second leading edge (55) and the second trailing edge (56); Equipped with the first and second chords (C1, C2) define a second plane (S) inclined with respect to the first plane (Q); the performance improvement kit having a second free end (81) opposite the first base end (80); A performance improvement kit, characterized in that the second chord (C2) is defined at the second free end (81).

13. 13. A performance improving kit according to claim 12, characterized in that the first and second planes (S, Q) are inclined to each other at an angle ranging between 0° and 30°.

14. Each of said elements (20) comprises a first edge (30) connected to said region (53) and a second edge (31) opposite said first edge (30) and connected to said second aerodynamic surface (21); 14. A performance improvement kit as claimed in claim 12 or 13, characterized in that each said second aerodynamic surface (21) extends at a distance gradually increasing from said region (53) along a third axis (Z) perpendicular to said first plane (Q) from said first edge (30) towards the tip of each respective said element (20).

15. A performance improvement method for a helicopter (1), comprising: The helicopter (1), a fuselage (2) elongated along a first longitudinal axis (X) of the helicopter (1) and extending between a nose (6) and a tail boom (7) of the helicopter (1); a horizontal stabilizer (9) arranged on the tail boom (7) and transverse to the tail boom (7); Equipped with the horizontal stabilizer (9) defines a pair of first aerodynamic surfaces (11) which, in use, generate separate first aerodynamic forces and are elongated along a second axis (Y) which is transverse to the first axis (X); said first and second axes (X, Y) define a first plane (Q); The performance improvement method comprises: i) arranging at least one first element (20) to connect said horizontal stabilizer (9) in a transverse direction to said first aerodynamic surface (11); ii) connecting at least one second aerodynamic surface (21) to said first element (20) facing said first aerodynamic surface (11) and spaced upward from said first aerodynamic surface (11), said second aerodynamic surface generating a second aerodynamic force; Equipped with Each of said second aerodynamic surfaces (21) comprises: a first base end (80) connected to each separate first element (20); a first front edge (55); a first rear edge (56) opposite said first front edge (55); a first chord (C1) connecting said first leading edge (55) and said first trailing edge (56) at a second free end (81) parallel to said first axis (X); a second chord (C2) parallel to said first axis (X) at a first base end (89) connecting said first leading edge (55) and said first trailing edge (56); Equipped with the first and second chords (C1, C2) define a second plane (R) inclined with respect to the first plane (Q); The performance improvement method comprises: each said second aerodynamic surface (21) comprises a second free end (81) spaced from said tail boom (7) and a fin (8) protruding from said tail boom (7) and opposite said first base end (80); The method of claim 1, wherein the second chord (C2) is defined at the second free end (81).

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