AIRCRAFT EMPENNAGE WITH A HORIZONTAL STABILIZER INTERFACING AT THE VERTICAL STABILIZER ROOT

Abstract

An aircraft empennage includes a vertical tail plane, a rear fuselage section attached to the vertical tail plane and including a skin and internal reinforcing members, a horizontal tail plane comprising two lateral torsion boxes and a framework located between the two lateral torsion boxes comprising a front spar, a rear spar and two ribs extending between the front and the rear spar and each adjacent to a lateral torsion box. The framework encloses a portion of the vertical tail plane along its spanwise direction. The aircraft empennage includes an attachment assembly attaching the framework to the rear fuselage section, the attachment assembly crossing the skin and extends between the internal reinforcing members of the rear fuselage section and the framework.

Claims

1. An aircraft empennage, comprising: a vertical tail plane, a rear fuselage section comprising a skin and internal reinforcing members, the vertical tail plane being attached to the rear fuselage section, a horizontal tail plane comprising two lateral torsion boxes, wherein the horizontal tail plane further comprises: a framework located between the two lateral torsion boxes and in connection with the two lateral torsion boxes, the framework comprising a front spar, a rear spar and two ribs extending between the front spar and the rear spar, each rib adjacent to a lateral torsion box, the framework enclosing a portion of the vertical tail plane along its spanwise direction, and an attachment assembly attaching the framework to the rear fuselage section, the attachment assembly crossing the skin and extending between the internal reinforcing members of the rear fuselage section and the framework.

2. The aircraft empennage, according to claim 1, wherein the attachment assembly attaching the framework to the rear fuselage section comprises: a rear attachment extending between the internal reinforcing members of the rear fuselage section and the rear spar of the framework, and a front attachment extending between the internal reinforcing members of the rear fuselage section and the front spar of the framework.

3. The aircraft empennage, according to claim 2, wherein the horizontal tail plane is trimmable, the connection between the rear attachment and the framework being configured to be a pivot of the trimmable horizontal tail plane and the front attachment being configured to move the trimmable horizontal tail plane around the pivot to control an angle of rotation of the horizontal tail plane.

4. The aircraft empennage, according to claim 3, wherein the front attachment comprises an endless screw.

5. The aircraft empennage, according to claim 4, wherein the front attachment comprises an actuator connected to the endless screw and configured to move the trimmable horizontal tail plane around the pivot to control the angle of rotation of the horizontal tail plane.

6. The aircraft empennage, according to claim 5, wherein the actuator is placed inside the rear fuselage section.

7. The aircraft empennage, according to claim 6, wherein the skin of the rear fuselage section comprises an opening that allows a passage of the endless screw.

8. The aircraft empennage, according to claim 1, wherein the framework is located at a root area of the vertical tail plane.

9. The aircraft empennage, according to claim 8, wherein the framework of the horizontal tail plane is located adjacent to the skin of the rear fuselage section with respect to a spanwise direction of the vertical tail plane.

10. The aircraft empennage, according to claim 1, wherein the vertical tail plane comprises a rudder, the rudder comprising a lower edge located adjacent to the rear attachment of the horizontal tail plane with respect to the spanwise direction of the vertical tail plane.

11. The aircraft empennage, according to claim 1, wherein the two lateral torsion boxes comprise a front spar and a rear spar, and the front spar of the framework being joined to the front spars of the lateral torsion boxes and the rear spar of the framework being joined to the rear spars of the lateral torsion boxes.

12. The aircraft empennage, according to claim 2, wherein the front attachment is joined to the framework near a longitudinal center of the front spar.

13. The aircraft empennage, according to claim 2, wherein the rear attachment comprises two lugs, each lug joined to the rear spar of the framework aligned with a longitudinal direction of each rib.

14. The aircraft empennage, according to claim 1, wherein the spars and the ribs of the framework are metallic.

15. An aircraft empennage, according to claim 1, wherein the spars and the ribs are made in composite materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0080] To complete the description and to provide for a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate preferred embodiments of the invention. The drawings comprise the following figures.

[0081] FIG. 1 shows a perspective view of an aircraft empennage known in the state of the art as Conventional tail.

[0082] FIG. 2 shows a lateral view of an aircraft empennage known in the state of the art as T-tail.

[0083] FIG. 3 shows a lateral view of an aircraft empennage known in the state of the art as Cross-tail.

[0084] FIG. 4 shows a perspective view of an upper shell of the rear fuselage section showing the structural attachment of the vertical tail plane (VTP) and of the horizontal tail plane (HTP).

[0085] FIG. 5 shows a perspective view of an aircraft empennage according to an embodiment of the invention.

[0086] FIG. 6 shows a schematic lateral view of an embodiment of the invention showing the interfaces between the rear fuselage section, the vertical tail plane (VTP) and the horizontal tail plane (HTP).

[0087] FIG. 7 shows a schematic plan view of the horizontal tail plane (HTP) and the vertical tail plane (VTP).

[0088] FIG. 8 shows a perspective view of an embodiment of the framework and of the front and the rear attachments to the rear fuselage section.

[0089] FIG. 9 shows a schematic plan view of an embodiment of the front spar of the framework and a dorsal fin covering the gap between the framework and the vertical tail plane (VTP).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0090] FIG. 1 discloses a Conventional tail known in the state of the art. This kind of tail comprises the vertical tail plane (VTP) (2) joined to the upper area of the rear fuselage section (1) and the horizontal tail plane (HTP) (3) crosses and is attached to the internal structure of the rear fuselage section (1).

[0091] FIG. 2 discloses a T-Tail configuration known in the state of the art. In this configuration, the horizontal tail plane (HTP) (3) is attached to the vertical tail plane (VTP) (2) at its upper part.

[0092] FIG. 3 discloses a Cross-Tail configuration known in the state of the art. In this configuration, the horizontal tail plane (HTP) (3) crosses the vertical tail plane (VTP) (2) near its middle part.

[0093] FIG. 4 discloses an upper shell of the rear fuselage section (1) showing the structural attachment of the vertical tail plane (VTP) (2). The rear fuselage section (1) comprises a skin (1.1) and internal reinforcing members, specifically, frames (1.3). The attachment of the vertical tail plane (VTP) (2) comprises vertical tail plane attachments (1.2) that are joined to the frames (1.3) and that crosses the skin (1.1) protruding from it (1.1) towards the vertical tail plane (VTP) (2). The shown attachment comprises pairs of lugs, each pair of lugs located between two consecutives frames (1.3).

[0094] FIG. 4 also discloses an embodiment of the attachment assembly attaching the framework (33) to the rear fuselage section (1). The attachment assembly crosses the skin (1.1) and extends between the frames (1.3) of the rear fuselage section (1) and the framework (33).

[0095] The attachment assembly shown in FIG. 4 comprises:

[0096] the rear attachment (4), specifically two lugs, extending between the frames (1.3) of the rear fuselage section (1) and the framework (33),

[0097] the front attachment (5) extending between the frames (1.3) of the rear fuselage section (1) and the framework (33).

[0098] FIG. 4 also illustrates the attachment assembly further comprising a fitting (4.2) configured for bearing the lateral loads of the horizontal tail plane (HTP) (3). The fitting (4.2) for bearing lateral loads extends between the two lugs of the rear attachment (4) and is aligned with the pivot (4.1).

[0099] FIG. 5 discloses a perspective view of an embodiment of the invention. An aircraft empennage is shown in which are depicted:

[0100] the rear fuselage section (1),

[0101] the vertical tail plane (VTP) (2) attached to the rear fuselage section (1), and

[0102] the horizontal tail plane (HTP) (3) located at the root area of the vertical tail plane (2).

[0103] FIG. 6 discloses a rear fuselage section (1) comprising vertical tail plane attachments (1.2) protruding from the skin (1.1) and being attached to the vertical tail plane (VTP) (2).

[0104] The shown vertical tail plane attachments (1.2) comprises three lugs. Alternatively, instead of having several independent lugs, a continuous fitting can be implemented.

[0105] It also shows that the horizontal tail plane (HTP) (3) is located at the lower part of the vertical tail plane (VTP) (2), i.e., it is located adjacent to the skin (1.1) of the rear fuselage section (1) at the root area of the vertical tail plane (VTP) (2). The horizontal tail plane (HTP) (3) is trimmable.

[0106] FIG. 6 also shows:

[0107] the rear attachment (4), and

[0108] the front attachment (5).

[0109] FIG. 7 discloses an embodiment of the invention showing a trimmable horizontal tail plane (HTP) (3) comprising:

[0110] The two lateral torsion boxes (31, 32).

[0111] The framework (33) which is located between the two lateral torsion boxes (31, 32). The framework (33) is connected to the two lateral torsion boxes (31, 32). The framework (33) comprises a front spar (34), a rear spar (35) and two ribs (36, 37). Each rib (36, 37) is located adjacent to a lateral torsion box (31, 32). Moreover, the framework (33) encloses a cross-section of the vertical tail plane (VTP) (2) such that a longitudinal portion of the vertical tail plane (VTP) (2) is surrounded by the framework (33).

[0112] The rear attachment (4) is attached to the rear spar (35) of the framework (33). The rear attachment (4) is also attached to the rear fuselage section (1), as it is shown in FIG. 6. The joint of the rear attachment (4) with the rear spar (35) is configured to be a pivot (4.1) of the trimmable horizontal tail plane (HTP) (3) as shown in FIG. 6.

[0113] FIG. 7 also discloses a plan view of the fitting (4.2) for bearing the lateral loads of the horizontal tail plane (HTP) (3) that extends between the two lugs of the rear attachment (4) and is aligned with the pivot (4.1). For the sake of clarity, FIG. 8 does not show the aforementioned fitting (4.2) to better show the rear spar (35).

[0114] The front attachment (5) is connected to the front spar (34) of the framework (33). The front attachment (5) is also connected to the rear fuselage section (1), as it is shown in FIG. 6. The front attachment (5) is configured to move the trimmable horizontal tail plane (HTP) (3) around the pivot (4.1) to control the angle of rotation of the horizontal tail plane (HTP) (3).

[0115] In the embodiment shown in FIG. 6, the front attachment (5) comprises an endless screw. Additionally, the front attachment (5) comprises an actuator (6), a trimmable horizontal stabilizers actuator (THSA), which is configured to control the angle of rotation of the horizontal tail plane (HTP) (3). The actuator (6) is connected to the endless screw. The endless screw is attached to the front attachment (5).

[0116] In the shown embodiment, the actuator (6) is placed inside the rear fuselage section (1), i.e., located on the side of the skin towards the median plane of the fuselage section. For that reason, the skin (1.1) of the rear fuselage section (1) comprises an opening to allow the endless screw to pass through it.

[0117] Furthermore, as the trimmable horizontal stabilizers actuator (THSA) (6) is kept inside the rear fuselage section (1), the vertical tail plane (VTP) (2) design is not penalized by the horizontal tail plane (HTP) (3) trimming actuation like in the case of the T-Tail and Cross-Tail configurations in which the vertical tail plane (VTP) (2) inner structure is impacted.

[0118] In the shown embodiment, the rear attachment (4) comprises a lug, specifically two lugs. Each lug is joined to the rear spar (35). Moreover, the two lugs are located aligned with the longitudinal direction of the framework ribs (36, 37) to minimize the effect of the loads on the rear spar (35). The attachment of these lugs to the framework (33) is implemented through bolts.

[0119] The front attachment (5) is placed near the longitudinal center of the front spar (34), to minimize the momentum by reducing the distance to the endless screw. More specifically, the front attachment (5) comprises two fittings (55) as it is shown in FIG. 8.

[0120] In a trimmable horizontal tail plane (HTP) (3), since the horizontal tail plane (HTP) (3) moves with respect to the vertical tail plane (VTP) (2) and the rear fuselage section (1), a standard clearance is left between the framework (33) and the other two structures in order to avoid any clash, as it is shown in FIGS. 6 and 7.

[0121] As previously stated, the framework (33) comprises two spars, front (34) and rear (35), and two ribs, left (36) and right (37). In order to attach the horizontal tail plane (HTP) (3) lateral boxes to the framework (33), the front spars (31.1, 32.1) and rear spars (31.2, 32.2) of the horizontal tail plane (HTP) (2) lateral boxes (31, 32) are joined respectively to the front spar (34) and rear spar (35) of the framework (33). Specifically, single lap-shear joints are used.

[0122] In addition, on top of the high loaded frames (1.3) defined in the rear fuselage section (1) to attach the vertical tail plane (VTP) (2), one additional high loaded frame will be needed in order to bear the loads coming from the rear support fittings. This additional high-loaded frame may be an intermediate one, or the rear fuselage closing frame like in the conventional empennage configuration.

[0123] In the case of the horizontal tail plane (HTP) (2) lateral box covers, they may be connected to the framework (33) by means of different structural solutions, like a single shear joint or a tension joint.

[0124] FIGS. 5 and 6 shows the horizontal tail plane (HTP) (3) located in the root area of the vertical tail plane (VTP) (2). The vertical tail plane (VTP) (2) comprises a rudder (2.1). In the shown embodiment, the rudder (2.1) comprises a lower edge (2.2) located adjacent to the rear attachment (4) of the horizontal tail plane (HTP) (3) with respect to the vertical direction of the aircraft empennage.

[0125] In an alternative embodiment, the horizontal tail plane (HTP) (3) may be located in an upper position of the vertical tail plane (VTP) (2).

[0126] Since the shape of the horizontal tail plane (HTP) (3) framework (33) is rectangular and the loading points from the horizontal tail plane (HTP) (3) are placed at the edges of the framework (33), it is necessary to stiffen the framework (33) in order to bear the momentum generated by these loads.

[0127] Since the inner area of the framework (33) is used in order to allocate the vertical tail plane (VTP) (2), the framework (33) is reinforced by means of corner fittings, ensuring there is no clash with the vertical tail plane (VTP) (2) surrounding structure.

[0128] The corner fittings and the lugs are so that the same bolts are used to attach these elements to the frame rear spar (35).

[0129] To manufacture the framework (33), two possibilities are depicted. To mechanize the full framework (33) using high performance metals. The framework (33) can be made in one piece. Another possibility is to have composite spars (34, 35) and ribs (36, 37) and metallic corner fittings to joint these elements among themselves. In an embodiment, the framework (33) may be manufactured together with one of the lateral torsion boxes (31, 32) or even the lateral torsion boxes (31, 32) and the framework (33) may be manufactured as one part.

[0130] The framework (33) may be covered by a fairing.

[0131] In order to allow the placement of the horizontal tail plane (HTP) (3) and the framework (33), the front and rear fairings of the vertical tail plane (VTP) (2) must have cut-outs where the framework (33) crosses their surface. These cut-outs must be big enough to grant rotation of the horizontal tail plane (HTP) (3), for example, +1° upwards and +15° downwards.

[0132] In addition, the empennage comprises a dorsal fin (60) as shown in FIG. 9. The dorsal fin (60) closes the gap between the framework (33) and the vertical tail plane (VTP) (2) to minimize the aerodynamic drag. The surface of the dorsal fin (60) comprises at least two flat portions, one on each of its port and starboard sides, where the horizontal tail plane (HTP) (3) fairing is in contact with the dorsal fin (60), so as to let the HTP (3) move upward and downward.

[0133] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.