Helicopter, helicopter kit and associated reconfiguration method

Abstract

A helicopter (1) is described, comprising: a tail boom (7); a vertical tail fin (8) projecting from the tail boom (7); and a horizontal tail fin (9) arranged at the tail boom (7) transversely to the vertical tail fin (8); at least one of the vertical tail fin (8) and the horizontal tail fin (9) defining a first aerodynamic surface (10, 11) generating a first air dynamic force; at least one first element (20, 90) transversely to the first aerodynamic surface (10, 11); and a second aerodynamic surface (21, 92) generating a second air dynamic force, which is connected to the first element (20, 90), faces the first aerodynamic surface (10, 11) and is spaced apart from the first aerodynamic surface; the second aerodynamic surface (21, 92) being spaced apart from the other of the vertical tail fin (8) and the horizontal tail fin (9).

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to European Patent Application No. 19219521.2, filed on 23 December 2019, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to helicopters, helicopter kits, and methods for reconfiguring helicopters. Background Technology

[0004] A helicopter, in a known manner, comprises a fuselage, a main rotor protruding from the fuselage and capable of rotating about a first axis, and a tail rotor protruding from the fuselage and capable of rotating about a second axis transverse to the first axis.

[0005] Specifically, the main rotor is adapted to provide the lift required to keep the helicopter in the air and to allow the helicopter to move forward / backward and laterally. Conversely, the tail rotor is adapted to counteract the rotation of the helicopter caused by the reaction torque transmitted to the fuselage through the operation of the main rotor and to control the yaw of the helicopter, i.e., rotation about the first axis.

[0006] Helicopters also include, in known ways:

[0007] The nose and tail beams are respectively located at opposite ends of the fuselage;

[0008] The vertical tail fin cantilever extends upwards from the tail boom of the fuselage and supports the tail rotor in a manner that allows it to rotate around a second axis; and

[0009] The horizontal tail, which protrudes laterally from the tail boom into the fuselage in a cantilever manner, is called the pitch stabilizer.

[0010] The vertical tail is shaped to have a wing profile that is configured to generate a first aerodynamic force with a primary component parallel to the second axis.

[0011] In this way, when the helicopter is flying forward at high speed, the first aerodynamic force generated by the vertical tail generates a reverse torque, which is added to the torque generated by the tail rotor and can maintain the helicopter at the desired yaw angle relative to a fixed direction.

[0012] Therefore, from a design perspective, it is desirable to increase the surface area of ​​the vertical tail fin in order to increase the value of the first aerodynamic force when the helicopter is flying forward at high speed.

[0013] However, when a helicopter is flying sideways, this increase in surface area of ​​the vertical tail leads to an increase in aerodynamic drag.

[0014] Therefore, the industry recognized the need to optimize the aerodynamic behavior of the vertical tail to increase the value of the primary aerodynamic force during high-speed forward flight, while not increasing aerodynamic drag during lateral flight.

[0015] The horizontal tail is configured to have a wing profile that generates a second aerodynamic force, lift / negative lift, with a primary component oriented parallel to the first axis when the helicopter is in forward flight.

[0016] This lift / negative lift, added to the lift generated by the main rotor, effectively maintains the helicopter's attitude in a stable state during high-speed forward flight; that is, ensures that the helicopter is in a stable equilibrium position regarding its vertical direction and its rotation about a third longitudinal axis. Specifically, the third axis is parallel to the fuselage's extension from the nose towards the tail boom and transverse to the first and second axes.

[0017] However, at certain low speeds, it may happen that the airflow guided downward by the main rotor deflects toward the tail of the fuselage, thereby impacting the horizontal tail and thus generating a third aerodynamic force on it, namely downward thrust.

[0018] After the helicopter accelerates and / or decelerates, the thrust causes the helicopter to adopt a nose-up attitude, i.e., the nose of the fuselage is higher than the tail. This nose-up attitude must be continuously corrected by the pilot acting on the cyclic pitch of the main rotor, i.e., by tilting the main rotor disk forward to move the airflow away from the horizontal stabilizer.

[0019] This makes it difficult for pilots to control the aircraft at certain low speeds.

[0020] In addition, the nose-up attitude of the aircraft during landing can cause visibility problems for the pilot, which can become more problematic in the event of gusts of wind, adverse weather conditions, or obstructions in the landing area.

[0021] Due to the above circumstances, the design of the horizontal tail fin must satisfy two conflicting constraints.

[0022] More specifically, on the one hand, a large horizontal tail surface is required to generate sufficient secondary aerodynamic values ​​and thus increase the longitudinal stability of the helicopter.

[0023] On the other hand, a small horizontal tail surface is optimal at low speeds to reduce the surface exposed to the downward airflow generated by the main rotor and the resulting nose-up of the helicopter, thus improving visibility and maneuverability in particularly critical situations (e.g., landing).

[0024] Due to these constraints, various horizontal tail configurations have been used on helicopters since the 1950s without achieving an optimal solution. For example, there are known asymmetrical horizontal tails located only on one side of the fuselage at different heights relative to the tail boom, and there are symmetrical designs with two stabilizers located at different heights and longitudinal positions relative to the fuselage.

[0025] US8,985,500 describes a helicopter that includes a horizontal tail fin comprising:

[0026] A pair of stabilizers that cantilever out from the corresponding sides of the tail boom;

[0027] A pair of pneumatic attachments, superimposed on the corresponding stabilizers and cantilevered from the corresponding sides of the fuselage; and

[0028] A pair of end plates, which are opposite to the corresponding sides and extend between each stabilizer and associated accessories.

[0029] When a helicopter is flying forward at high speed, the aerodynamic wash generated by the fuselage and main rotor significantly interferes with the airflow of the adjacent fuselage portion that impacts the attachments.

[0030] Therefore, these parts are aerodynamically "in the shadows" and cannot effectively help generate the secondary aerodynamic forces required for longitudinal stability of the helicopter.

[0031] Therefore, the industry recognized the need to optimize the aerodynamic behavior of the horizontal tail to increase the longitudinal stability of helicopters during forward flight, while limiting nose-up at low speeds.

[0032] The industry also recognizes the need to optimize the aerodynamic behavior of the horizontal and vertical tails for the angle-of-attack characteristics during forward flight, lateral flight, and low-speed phases of landing / takeoff, thereby limiting or even avoiding any increase in size and / or maximum aerodynamics at typical stall angles of attack.

[0033] US-A-2,353,856 discloses an auxiliary airfoil for preventing turbulence on control surfaces. The auxiliary airfoil is particularly suitable for the tail surface to smooth flow over the stabilizer and elevator. The primary purpose of the airfoil is to achieve smooth airflow in the region adjacent to the intersection of the two stabilizers when one stabilizer control surface must be cut to allow the deflection of another stabilizer control surface.

[0034] US-B-8,579,226 discloses an aircraft with a pair of wings and associated attachments. Each attachment is shaped to give the associated wing a closed box shape. Summary of the Invention

[0035] The object of this invention is to produce a helicopter that can meet at least one of the above-mentioned requirements in a simple and inexpensive manner.

[0036] According to the present invention, the above objective is achieved by the helicopter according to claim 1.

[0037] The present invention also relates to a kit for a helicopter according to claim 12.

[0038] The present invention also relates to a method for reconfiguring a helicopter according to claim 14. Attached Figure Description

[0039] To better understand the invention, three preferred, non-limiting embodiments of the invention are described below by way of example only and with the aid of the accompanying drawings, in which:

[0040] Figure 1 This is a perspective view of a helicopter manufactured according to the present invention;

[0041] Figure 2 yes Figure 1 A magnified view of the tail section of a helicopter.

[0042] Figure 3 It is along Figure 2 Section III-III of the line has some parts removed for clarity;

[0043] Figure 4 This is a cross-section of the tail section of a helicopter according to a second embodiment of the present invention; and

[0044] Figure 5 This is a cross-section of the tail section of a helicopter manufactured according to a third embodiment of the present invention. Detailed Implementation

[0045] Referring to the accompanying drawings, reference numeral 1 indicates a helicopter manufactured according to the provisions of the present invention.

[0046] The helicopter 1 basically includes a fuselage 2, a main rotor 3 located on top of the fuselage 2, and a tail rotor 5.

[0047] The fuselage 2 includes a nose 6 and a tail boom 7 at its two opposite ends.

[0048] It can be defined as:

[0049] The roll axis X of helicopter 1, corresponding to the longitudinal extension direction of fuselage 2;

[0050] The pitch axis Y is orthogonal to the X-axis; and

[0051] The yaw axis Z is orthogonal to axes X and Y.

[0052] The axes X, Y, and Z are integral with helicopter 1 and are incident on the center of gravity G of helicopter 1 (not shown in the correct position in the accompanying drawings for simplicity).

[0053] It should be noted that in the following text, in this specification, terms such as “above,” “below,” “side,” “in front,” and “in rear” are used with reference to the normal forward direction of the helicopter 1 flying forward at a constant altitude (i.e., the axis Z is vertical and the axes X and Y are horizontal).

[0054] The main rotor 3 is adapted to provide thrust with a main component parallel to the axis Z so as to keep the helicopter 1 in the air, forward or backward movement parallel to the axis X, and lateral movement in two directions parallel to the axis Y.

[0055] The tail rotor 5 is adapted to provide thrust with a primary component parallel to the axis Y. This thrust generates torque about the axis Z in the opposite direction to the reaction torque acting on the fuselage 2 after the main rotor 3 has been in operation, in order to control the yaw angle of the helicopter 1.

[0056] The nose 6 and tail boom 7 are opposite each other along the longitudinal extension axis X of the helicopter 1.

[0057] Helicopter 1 also includes:

[0058] Vertical tail fin 8, which cantilevered from the top of tail boom 7 at the end opposite the nose 6; and

[0059] The horizontal tail 9 protrudes cantilevered from the tail boom 7 below the vertical tail 8 and is adapted to stabilize the helicopter 1 longitudinally (i.e. along the axis X).

[0060] Vertical tail fin 8 supports tail rotor 5.

[0061] The vertical tail 8 defines an aerodynamic surface 10, which is configured to generate aerodynamic forces with a principal component parallel to the Y-axis. Thus, when the helicopter 1 is flying forward at high speed, the lift generated by the vertical tail 8 helps to control the yaw angle of the helicopter 1.

[0062] The horizontal tail 9 is adapted to generate aerodynamics with a principal component parallel to the axis Z, so as to longitudinally stabilize the helicopter 1 in forward flight, that is, to stabilize the attitude of the helicopter 1 in rotation about the axis Y.

[0063] More specifically, the horizontal tail fin 9 includes a pair of stabilizers 14 disposed on corresponding opposing sides of the tail boom 7.

[0064] Since stabilizers 14 are identical to each other, only one stabilizer 14 will be mentioned in the following description.

[0065] The stabilizer 14 has a length parallel to axis Y, a width parallel to axis X, and a thickness parallel to axis Z.

[0066] Stabilizer 14 includes a bearing surface 11 configured to generate lift / negative lift with a principal component parallel to axis Z.

[0067] The surface 11 of the stabilizer 14 is further defined by the following parts:

[0068] Leading edge 15, which faces the nose 2 and defines the first foremost edge of the stabilizer 14;

[0069] The trailing edge 16, which is opposite to the leading edge 15 along the axis X, defines the second rearmost edge of the stabilizer 14;

[0070] Top surface 17, defined between leading edge 15 and trailing edge 16, and defining the upper surface of stabilizer 14; and

[0071] The bottom surface 18, which is defined on the opposite side of the top surface 17 between the leading edge 15 and the trailing edge 16, defines the lower surface of the stabilizer 14.

[0072] Surface 11 also includes a pair of end edges 12a, 12b that are opposite each other and parallel to the axis Y. The end edge 12a of each surface 11 is fixed to the tail beam 7.

[0073] Advantageously, the stabilizer 14 includes:

[0074] A plate 20 protruding laterally from surface 11 in a cantilever manner; and

[0075] An accessory 21 is defined as an additional aerodynamic surface, which is laterally connected to the plate 20, spaced apart from the surface 11 parallel to the axis Z, and spaced apart from the vertical tail 8 parallel to the axis Y.

[0076] More specifically, plate 20 is opposite to vertical tail fin 8 along axis Y and is connected to surface 11.

[0077] The stabilizer 14 also includes an additional plate 22 that cantilevered from the attachment 21 and was connected to the surface 11.

[0078] More specifically, plate 22 is spaced apart from plate 20 parallel to axis Y, and is located between vertical tail fin 8 and plate 20 parallel to axis Y.

[0079] Plate 22 extends laterally to attachment 21 and surface 11.

[0080] Thus, the portion 23 of plates 20, 22, accessory 21, and stabilizer 14 located between plates 20 and 22 defines a closed wing surface 25.

[0081] More specifically, plate 20 is defined parallel to axis Z by edge 30 adjacent to surface 11 and edge 31 opposite to edge 30.

[0082] Plate 20 also includes region 32, which is parallel to axis Z and located between edges 30 and 31, and attachment 21 is connected to region 32.

[0083] In the case shown, edge 31 is positioned above region 32.

[0084] Edges 30, 31 and region 32 extend parallel to axis X.

[0085] Annex 21 is also defined by the following parts:

[0086] Leading edge 35, which faces the nose 6 and defines the first foremost edge of attachment 21;

[0087] The trailing edge 36, which is opposite to the leading edge 15 along the axis X and defines the second rearmost edge of the attachment 21;

[0088] Top surface 37, defined between leading edge 35 and trailing edge 36, and defining the upper surface of attachment 21; and

[0089] The bottom surface 38 is defined between the leading edge 35 and the trailing edge 36 on the side opposite to the top surface 37, and defines the lower surface of the attachment 21.

[0090] Reference Figure 2 and Figure 3 The bottom surface 38 of Annex 21 is located along axis Z between the top surface 37 of Annex 21 and the top surface 17 of surface 11.

[0091] In other words, Attachment 21 is superimposed on surface 11 along axis Z.

[0092] Annex 21 also includes a pair of end edges 24a, 24b opposite to each other, which are parallel to axis Y and connected to plate 20 and plate 22 respectively.

[0093] Annex 21 also has a length parallel to axis Y and a width parallel to axis X.

[0094] Plate 22 also includes an edge 40 connected to attachment 21 and an edge 41 connected to surface 11.

[0095] Edges 40 and 41 are opposite each other and extend parallel to axis Z and parallel to axis Y.

[0096] In the case shown, edge 40 is positioned above edge 41.

[0097] In the case shown, with a plane orthogonal to the axis Y and passing through edge 41 as a reference, plate 22 is inclined from edge 41 toward edge 40 toward plate 20.

[0098] Reference Figure 3 The stabilizer 14 also includes a pair of flaps 50 (also known as Gurney flaps) which are applied to the respective opposite sides of the trailing edge 16 of the surface 11, are located in the same plane and are orthogonal to the trailing edge 16 to form a T-shape.

[0099] Specifically, part 23 includes:

[0100] Region 53, which is parallel to axis Y adjacent to plate 20 and parallel to axis X, lies between segment 56 of leading edge 15 and corresponding segment 57 of trailing edge 16; and

[0101] Flaps 50.

[0102] exist Figure 2 In the case shown, the wingspan 60 of region 53 (i.e., the extension range parallel to axis Y) is between approximately 5% and 35% of the wingspan 61 of annex 21, preferably between 15% and 20%.

[0103] Reference Figure 3 The chord 62 of Annex 21 (i.e., the distance between the leading edge 35 and the trailing edge 36) is between approximately 5% and 100% of the chord 63 of surface 11 (i.e., the distance between the leading edge 15 and the trailing edge 16), preferably between approximately 30% and 70%.

[0104] The distance 64 between the chords 62 and 63, measured parallel to axis Z, is between approximately 5% and 120% of the chord 63 on surface 11, preferably between approximately 20% and 100%.

[0105] The distance 65 between the chord 62 and the edge 31 is between 40% and 55% of the chord 63 of the surface 11.

[0106] The distance 66 between the chord 63 and the edge 31 is between 110% and 120% of the chord 63 on the surface 11.

[0107] The distance 67 between the leading edge 35 and the leading edge 15, parallel to the axis X, is between 50% of the chord 63 when facing the nose 6 and 50% of the chord 63 when facing the opposite side of the nose 6.

[0108] Plates 20, 22, accessory 21, area 53 of stabilizer 14, and Gurney flap 50 form a reconfiguration kit 80 for a helicopter stabilizer. Figure 2The reconfiguration kit 80 includes surface 11 but not part 23.

[0109] The vertical tail 8 is shaped in a manner very similar to that of the stabilizer 14, wherein the surface 10 of the vertical tail 8 is considered instead of the surface 11, and therefore only the surface 10 is described in summary below.

[0110] In particular, where possible, Figure 2 and Figure 3 The corresponding or equivalent parts of the vertical tail fin 8 and the stabilizer 14 are shown in the same figures.

[0111] The vertical tail 8 includes a support 90 adapted to support the rotor 5 and cantilevered laterally to the surface 11 from two sides 13a, 13b of the vertical tail 8.

[0112] On the side 13b opposite to rotor 5 along axis Y, the vertical tail fin 8 includes:

[0113] Plate 91, which cantilevered laterally to surface 11, is curved and lies between support 90 and stabilizer 14; and

[0114] Annex 92 defines an additional aerodynamic surface that extends between support 90 and plate 91 and is spaced apart from surface 11 parallel to axis Y.

[0115] The vertical tail fin 8 also includes a portion 93 located along axis Z between the support member 90 and the plate 91.

[0116] In the case shown, the support member 90 is positioned above the plate 91.

[0117] Plate 91 and Annex 92 are completely similar to Plate 22 and Annex 21, respectively, and therefore are not described in detail below.

[0118] The support 90, plate 91, accessory 92 and the portion 93 of the vertical tail 8 between the support 90 and plate 92 define a closed wing surface 95, which generates aerodynamic forces with a principal component parallel to the axis Y during the forward flight of the helicopter 1.

[0119] The support 90, plate 91, accessory 92, and part 93 of stabilizer 14 form a reconfiguration kit 100 for a stabilizer used on a helicopter. Figure 2 The reconfiguration kit 100 includes surface 10, but not part 93.

[0120] The operation of helicopter 1 is described starting from, for example, the typical low-speed forward flight or hovering state during takeoff / landing.

[0121] In this state, the reaction torque around axis Z generated on the fuselage 2 by the operation of the main rotor 3 is essentially balanced by the tail rotor 5. In fact, due to the low or zero speed of the helicopter 1, the aerodynamic force generated by the vertical tail 8 is negligible.

[0122] Furthermore, in this state, the downwash from the main rotor 3 toward the tail boom 7 impacts the stabilizer 14 of the horizontal tail 9.

[0123] The attachment 21 positioned above the surface 11 obstructs the flow of the wash stream toward the surface 11, thus subjecting the surface 11 to a particularly low or zero downward thrust due to the wash stream from the main rotor 3.

[0124] Furthermore, the small overall extension of Annex 21 can further reduce the downward thrust exerted by the wash flow on the horizontal tail fin 9.

[0125] Therefore, the upward torque of the nose around axis Y generated by this thrust is reduced, which in turn reduces the attitude changes of helicopter 1 and the corrections required by the pilot during takeoff / landing.

[0126] Conversely, in high-speed forward flight, the vertical tail 8 effectively helps to counteract the reaction torque generated by the main rotor 3 due to the aerodynamics produced by the surface 10 and attachment 92.

[0127] Furthermore, in these states, the horizontal tail 9 generates aerodynamic thrust with a component parallel to the axis Z, which enables the helicopter 1 to maintain stable balance in translation along the axis Z and rotation about the axis Y.

[0128] The presence of fuselage 2 interfered with the aerodynamic flow of impacting vertical tail 8 and horizontal tail 9.

[0129] In particular, the airflow in the region adjacent to the vertical tail 8 that impacts the horizontal tail 9 and therefore the region adjacent to the vertical tail 8 that impacts the surface 11 is substantially smaller than the airflow in the closed wing surface 25 of the impact stabilizer 14.

[0130] Similarly, the airflow impacting the closed wing surface 95 of the vertical tail 8 is substantially smaller in the region adjacent to the horizontal tail 9 and therefore in the region adjacent to the horizontal tail 9 of the surface 10, compared to the airflow impacting the vertical tail 8.

[0131] In lateral flight, the airflow impacting the surface 10 of the vertical tail 8 is substantially smaller than the airflow impacting the attachment 92. In other words, surface 10 is aerodynamically protected by attachment 92. Therefore, the aerodynamic drag provided by the vertical tail 8 is particularly reduced in lateral flight.

[0132] Kit 80 is used to reconfigure a helicopter equipped with stabilizers, each of which consists only of surface 11 and no part 23.

[0133] More specifically, plates 20 and 22 are fixed to the edges 30 and 41 of surface 11 so that attachment 21 is positioned facing surface 11.

[0134] Region 53 is connected to surface 11 to define the latter's extension.

[0135] Specifically, region 53 is parallel to axis Y and connected to the associated plate 20.

[0136] Similarly, kit 100 is used to reconfigure a helicopter equipped with a vertical tail that includes only the surface 10 of the helicopter to be configured.

[0137] More specifically, plate 91 is fixed to surface 10 so that attachment 92 is positioned facing surface 10 of helicopter 1 to be configured, and attachment 92 is fixed to support 90.

[0138] Reference Figure 4 Reference numeral 14' indicates a stabilizer for a helicopter 1 according to another embodiment of the present invention.

[0139] Stabilizer 14' is similar to stabilizer 14 and will be described below only in terms of differences; where possible, the same or equivalent parts of stabilizers 14 and 14' will be indicated by the same reference numerals.

[0140] The difference between stabilizer 14' and stabilizer 14 is that stabilizer 14' includes:

[0141] At least one attachment 21' is disposed along axis Z on the top surface 17 side of surface 11 and spaced apart from the vertical tail fin 8 along axis Y, and at least one additional attachment 21' is disposed along axis Z on the bottom surface 18 side of surface 11 and spaced apart from the tail boom 7 along axis Y.

[0142] In particular, there may be more than one Annex 21' and / or more than one additional Annex 21'.

[0143] Reference Figure 5 Reference numeral 14' indicates a stabilizer for a helicopter 1 according to another embodiment of the present invention.

[0144] Stabilizer 14” is similar to stabilizer 14 and will be described below only in terms of differences; where possible, the same or equivalent parts of stabilizers 14 and 14” will be indicated by the same reference numerals.

[0145] The difference between stabilizer 14 and stabilizer 14 is that stabilizer 14 includes at least two attachments 21 disposed on the top surface 17 side of surface 11, spaced apart from the vertical tail 8 and offset along the axis X.

[0146] Alternatively, stabilizer 14 may include at least two attachments 21 disposed on the bottom surface 18 side of surface 11, spaced apart from vertical tail 8 and offset along axis X.

[0147] Based on the examination of the characteristics of helicopter 1, kits 80 and 100 and the method according to the invention, the advantages that can be obtained are obvious.

[0148] Specifically, the attachment 21 of the stabilizer 14 generates aerodynamics and is spaced apart from the corresponding surface 11 parallel to the axis Z and from the vertical tail 8 parallel to the axis Y.

[0149] Thus, at high speeds, the aerodynamic force of lift / negative lift generated by attachment 21 along axis Z is added to the lift / negative lift generated by surface 11, which in turn contributes to the main effect of increasing the longitudinal stability of helicopter 1.

[0150] On the other hand, since the annex 21 is spaced apart from the vertical tail 8, the stabilizer 14 is lighter and smaller than the stabilizers of the known schemes described in the introductory section of this specification, which is a significant advantage for the helicopter 1.

[0151] Because the fuselage 2 and main rotor 3 significantly interfere with the airflow in the area between attachment 21 and vertical tail 8, the aerodynamics generated in this area are quite inefficient, thus the weight reduction is achieved without any adverse effect on the aerodynamics generated by stabilizer 14.

[0152] In other words, the horizontal tail 9 achieves high longitudinal stability of the helicopter 1 while reducing weight.

[0153] At low speeds, surface 11 is within the turbulent wash flow of attachment 21. Therefore, compared to conventional solutions, the downward thrust generated by the wash flow of the main rotor 3 on the horizontal tail 9 is reduced, thereby reducing the tendency of the helicopter 1 to adopt a nose-up attitude during landing operations, thus improving pilot comfort and visibility.

[0154] Each stabilizer 14 also includes an associated closed wing surface 25 defined by plates 20, 22, attachment 21 and a portion 23 of the stabilizer 14 between plates 20, 22.

[0155] The enclosed wing surface 25 significantly reduces the negative impact of drag and maximizes the efficiency of the corresponding stabilizer 14 (i.e., the ratio between lift and generated drag). Therefore, the stabilizer 14 increases the value of the generated aerodynamic forces with the same surface area, or allows the same force to be generated with a smaller surface area, thus ensuring the longitudinal stability of the helicopter 1 with a smaller weight and volume.

[0156] Similar to the horizontal tail 9, the presence of attachment 92 generates additional aerodynamic forces besides those generated by surface 10. Therefore, the vertical tail 8 can increase the total aerodynamic force generated during high-speed flight, with a component parallel to the axis Y.

[0157] Since the attachment 92 is spaced apart from the horizontal tail 9, the total weight of the vertical tail 8 can be reduced without worsening the overall aerodynamic performance. However, the area between the attachment 92 and the horizontal tail 9 is in a turbulent wash flow generated by the main rotor 3 and the fuselage 2, and is therefore essentially inefficient from an aerodynamic point of view.

[0158] On the other hand, referring to the lateral flight state of helicopter 1, that is, the state in which the helicopter moves laterally parallel to the axis Y, surface 10 is in the wash flow of attachment 92 and is therefore subjected to more impacts from the turbulent airflow. This results in a reduction in the overall aerodynamic drag of the vertical tail 8 in the lateral flight state.

[0159] Therefore, the increase in drag of the vertical tail 8 during lateral flight 8 caused by the increase in aerodynamics obtained at high speed is significantly smaller than the result obtained by simply increasing the extension of the surface 10 without introducing Annex 21.

[0160] Similar to each stabilizer 14, the vertical tail 8 includes a closed wing surface 95 defined by a support 90, a plate 91, an accessory 92, and a portion 93 between the support 90 and the plate 91.

[0161] Similar to the closed wing surface 25, the wing surface 95 also significantly reduces the negative impact of drag and maximizes the efficiency of the vertical tail 8 (i.e., the ratio between lift and drag). Due to the presence of the closed wing surface 95, the value of the generated aerodynamic force is increased for the same surface area, or the same force can be generated with a smaller surface area, thus ensuring yaw control of the helicopter 1 at high speeds in an aerodynamically efficient manner.

[0162] In summary, the applicant has observed that the introduction of Annexes 21 and 92 can increase the lift slope of the lift coefficient relative to the angle of attack, thereby reducing the increase in maximum lift under stall conditions.

[0163] Since the angle of attack of the vertical tail 8 and horizontal tail 9 corresponding to the normal flight states of helicopter 1—forward flight, lateral flight, hovering, and low-speed flight during takeoff / landing—is smaller than the stall angle of attack, Annexes 21 and 92 can increase the value of the aerodynamic force generated by the vertical tail 8 and horizontal tail 9 at the typical angle of attack of helicopter 1 during operation.

[0164] The flaps 50, applied orthogonally to the trailing edge 16, can increase the aerodynamic forces generated by the surface 11 relative to a small increase in aerodynamic drag. In particular, due to the T-shape of the flaps 50 and the trailing edge 16, the maximum values ​​of the lift / negative lift and lift coefficient generated by the surface 11 can be increased with changes in angle of attack.

[0165] Annexes 21' and 21" allow for increased aerodynamics generated by the horizontal tail 9, and thus increased stability at high speeds, thereby further increasing the protection of surface 11 from the downwash generated by the main rotor 3.

[0166] Kits 80 and 100 can be easily reconfigured for helicopters with conventional vertical and horizontal tails in the following ways:

[0167] Plates 20 and 22 are secured to edges 30 and 41 of surface 11 to position attachment 21 facing surface 11, and region 53 is secured to surface 11 to define its extension; and / or

[0168] Secure plate 91 to the corresponding edge of surface 10 and attach accessory 92 to support 90 so that accessory 92 is positioned facing surface 10 of the helicopter to be configured.

[0169] Since plate 22 is spaced apart from vertical tail 8, the application of kit 80 does not require any action on tail boom 7, thus greatly simplifying the reconfiguration of helicopter 1.

[0170] Similarly, since the plate 92 is spaced apart from the stabilizer 14, the application of the kit 100 does not require any action on the horizontal tail 9, thus further simplifying the reconfiguration of the helicopter 1.

[0171] The T-shaped attachment 50 is particularly advantageous when included in the kit 80. In fact, the T-shape allows for an increase in lift generated by the stabilizer 14 relative to the absence of the kit 80, without altering the attitude of the helicopter 1.

[0172] Obviously, modifications and variations can be made to the helicopter 1, kits 80 and 100 and the method described herein without departing from the scope defined in the claims.

[0173] Specifically, each stabilizer 14 may not include the associated plate 22. Similarly, the vertical tail 8 may not include the plate 91.

[0174] In addition, each stabilizer 14 may include a plate 22 spaced apart from the associated surface 11 along the axis Z. Similarly, the vertical tail fin 8 may include a plate 91 spaced apart from the associated surface 10 along the axis Z.

[0175] Component 90 may not be a rotor support component.

[0176] Finally, Annexes 21' and 22" can be carried by the vertical tail 8 instead of by stabilizers 14 and 14'.

Claims

1. A helicopter comprising: a tail boom; a vertical tail projecting from the tail boom; and a horizontal tail provided at the tail boom and transversely to the vertical tail; the horizontal tail defining a first aerodynamic surface generating, in use, a first air dynamic force; characterized in that it comprises: at least one first element transversely to the first aerodynamic surface; and a second aerodynamic surface generating, in use, a second air dynamic force, the second aerodynamic surface being connected with the first element, facing the first aerodynamic surface and spaced apart from the first aerodynamic surface; the second aerodynamic surface being spaced apart from the vertical tail; the second aerodynamic surface extending in a spanwise direction parallel to a spanwise direction of the first aerodynamic surface, the helicopter comprising a second element spaced apart from the first element, the second element being transversely to the first aerodynamic surface and to the second aerodynamic surface and extending from the second aerodynamic surface towards the first aerodynamic surface, the second element being connected with the first aerodynamic surface, and the first element, the second element, the second aerodynamic surface and the portion of the first aerodynamic surface between the first aerodynamic surface and the second aerodynamic surface defining an enclosed wing surface, the first aerodynamic surface comprising a first top surface and a first bottom surface, the second aerodynamic surface comprising a second top surface and a second bottom surface opposite to each other, the second bottom surface facing the first top surface; the helicopter further comprising a main rotor operable to generate, in use, an airflow along a first axis (Z) and directed towards the horizontal tail; the second aerodynamic surface being disposed upstream of the first aerodynamic surface transversely to the first axis (Z) with reference to a forward direction of travel of the airflow. the first aerodynamic surface comprising a first leading edge and a first trailing edge opposite to each other with reference to a normal forward direction of the helicopter, the normal forward direction of the helicopter being oriented from the tail boom towards a nose of the helicopter; 2. The helicopter according to claim 1, characterized in that the second aerodynamic surface comprising a second leading edge and a second trailing edge opposite to each other with reference to the normal forward direction; wherein the first leading edge is disposed in a forward position with respect to the second leading edge with reference to the normal forward direction; and / or wherein the first trailing edge is disposed in a rearward position with respect to the second trailing edge with reference to the normal forward direction. it comprises a pair of appendices applied on at least one of the first trailing edge and the second trailing edge and transversely to the at least one trailing edge, the pair of appendices being disposed on respective opposite sides of the at least one of the first trailing edge and the second trailing edge so as to form a T-shaped configuration with the at least one of the first trailing edge and the second trailing edge.

3. The helicopter according to claim 2, characterized in that 4. The helicopter according to any one of claims 1-3, ​ characterized in that The helicopter comprises at least two said second aerodynamic surfaces disposed on the same said first top surface side or said first bottom surface side of said first aerodynamic surface; and / or It comprises at least one said second aerodynamic surface disposed on said first top surface side and at least one further said second aerodynamic surface disposed on said first bottom surface side of said first aerodynamic surface.

5. The helicopter according to any one of claims 1-3, characterized in that, The first element is disposed on a first end of the first aerodynamic surface, the first end being opposite the vertical tail.

6. The helicopter according to any one of claims 1-3, characterized in that, The horizontal tail comprises a pair of stabilizers projecting in cantilever fashion from opposite sides of a fuselage of the helicopter; Each said stabilizer comprises a corresponding said first aerodynamic surface, a corresponding said second aerodynamic surface and a corresponding said first element.

7. A helicopter comprising: a tail boom; a vertical tail projecting from the tail boom; and a horizontal tail disposed at the tail boom and transverse to the vertical tail; The vertical tail defines a first aerodynamic surface generating in use a first air dynamic force; It is characterized in that the helicopter comprises: at least one first element transverse to the first aerodynamic surface; and a second aerodynamic surface generating in use a second air dynamic force, the second aerodynamic surface being connected with the first element, facing the first aerodynamic surface and spaced apart from the first aerodynamic surface; The second aerodynamic surface is spaced apart from the horizontal tail; The second aerodynamic surface extends in a wingspan direction parallel to a wingspan direction of the first aerodynamic surface, The helicopter comprises a second element spaced apart from the first element, the second element being transverse to the first aerodynamic surface and the second aerodynamic surface and extending from the second aerodynamic surface towards the first aerodynamic surface, The second element is connected with the first aerodynamic surface, and The first element, the second element, the second aerodynamic surface and the part of the first aerodynamic surface between the first aerodynamic surface and the second aerodynamic surface define an enclosed wing surface.

8. An upgrade kit for a helicopter, the upgrade kit comprising: at least one first element securable transversely to a first aerodynamic surface defined by a horizontal tail of the helicopter; a second aerodynamic surface transverse to the first element and adapted to generate in use an air dynamic force; The first element comprises: an edge securable to the first aerodynamic surface; and an area separate from the edge, the second aerodynamic surface projecting in cantilever fashion from the area; The second aerodynamic surface is configured to be disposed in use at a distance from a vertical tail of the helicopter; The second aerodynamic surface extends in a wingspan direction parallel to a wingspan direction of the first aerodynamic surface; The kit further comprises: a second element spaced from said first element, said second element being transverse to said first aerodynamic surface and said second aerodynamic surface and extending from said second aerodynamic surface towards said first aerodynamic surface, said second element being connected to said first aerodynamic surface, and said first element, said second element, said second aerodynamic surface and the portion of said first aerodynamic surface comprised between said first aerodynamic surface and said second aerodynamic surface define a closed wing surface, said first aerodynamic surface comprising a first top surface and a first bottom surface, said second aerodynamic surface comprising a second top surface and a second bottom surface opposite to each other, said second bottom surface facing said first top surface; the main rotor of said helicopter being operable to generate, in use, an airflow directed along a first axis (Z) and towards said tail plane, said second aerodynamic surface being arranged upstream of said first aerodynamic surface with respect to a forward direction of travel of said airflow, transverse to said first axis (Z).

9. An upgrading method for a helicopter; said helicopter comprising: a tail boom; a vertical tail projecting from said tail boom; and a tail plane arranged at said tail boom and transverse to said vertical tail; said tail plane defining a first aerodynamic surface; said method comprising the steps of: i) arranging a first element transverse to said first aerodynamic surface; ii) arranging a second aerodynamic surface spaced from said first aerodynamic surface and spaced from said vertical tail; and iii) connecting said second aerodynamic surface to said first element; said second aerodynamic surface extending in a wingspan direction parallel to a wingspan direction of said first aerodynamic surface, iiii) arranging a second element spaced from said first element transverse to said first aerodynamic surface and said second aerodynamic surface, so that second element extends from said second aerodynamic surface towards said first aerodynamic surface; v) arranging said second element connected to said first aerodynamic surface, said first element, said second element, said second aerodynamic surface and the portion of said first aerodynamic surface comprised between said first aerodynamic surface and said second aerodynamic surface define a closed wing surface, said first aerodynamic surface comprising a first top surface and a first bottom surface, said second aerodynamic surface comprising a second top surface and a second bottom surface opposite to each other, said second bottom surface facing said first top surface; the main rotor of said helicopter being operable to generate, in use, an airflow directed along a first axis (Z) and towards said tail plane, said second aerodynamic surface being arranged upstream of said first aerodynamic surface with respect to a forward direction of travel of said airflow, transverse to said first axis (Z).

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