CENTRAL AREA ARRANGEMENT FOR CONTINUOUS HORIZONTAL TAIL PLANE TORSION BOX

Abstract

An aircraft horizontal tail plane (HTP) of the continuous type, wherein the inner-most ribs of the right-hand side and left-hand side torsion boxes are arranged to have one end joined right at the joint zone where both rear spars meet at axis of symmetry of the HTP. In this way, the loads at this central region of the HTP are concentrated at the joint zone where the inner-most ribs and the rear spars converge. The HTP can be manufactured with a reduced number of components.

Claims

1-10. (canceled)

11. A horizontal tail plane for an aircraft comprising: first and second lateral torsion boxes joined to each other at a central region thereof and symmetrically arranged with respect to an axis of symmetry of the horizontal tail plane, wherein each of said lateral torsion boxes comprises front and rear spars, and a plurality of ribs having ends respectively joined to the front and rear spars, and wherein the rear spars of the first and second lateral torsion boxes are joined to each other at a joint zone at the symmetry axis of the horizontal tail plane, and wherein an inner-most rib of each from the first and second lateral torsion boxes are arranged as to converge towards said joint zone.

12. The horizontal tail plane according to claim 11 further comprising: upper and lower covers obtained from a composite material and extending from a first tip of the horizontal tail plane to a second tip of the horizontal tail plane, and wherein said upper and lower covers have been obtained by an automated composites manufacturing process as an unitary body.

13. The horizontal tail plane according to claim 11 wherein all the ribs of the first and second torsion boxes are either: positioned to define an angle different than 0° with respect to the axis of symmetry (X) of the horizontal tail plane; or positioned parallel to the axis of symmetry (X) of the horizontal tail plane.

14. The horizontal tail plane according to claim 11 wherein the first and second lateral torsion boxes further comprise a plurality of stringers longitudinally arranged in each of the torsion boxes, and wherein at least one stringer of each lateral torsion box, has a first end end located at a plane defined by the inner-most rib of the respective lateral torsion box.

15. The horizontal tail plane according to claim 14 wherein the at least one stringer of each lateral torsion box includes a run-out section at first end, and wherein at least a part of this run-out section is covered by the respective inner-most rib.

16. The horizontal tail plane according to claim 14 wherein the stringer and the inner-most rib are co-bonded together.

17. The horizontal tail plane according to claim 16 wherein the stringers are omega-shaped or T-shaped stringers.

18. The horizontal tail plane according to claim 15 wherein the stringer and the inner-most rib are co-bonded together.

19. The horizontal tail plane according to claim 15 wherein the stringers are omega-shaped or T-shaped stringers.

20. The horizontal tail plane according to claim 12 wherein at least one of said upper and lower covers is thicker in an area at the central region of the horizontal tail plane.

21. The horizontal tail plane according to claim 11 wherein the inner-most ribs are arranged to define a straight angle with the respective rear spar to which is joined.

22. The horizontal tail plane according to claim 11 further comprising: a reinforcement metallic plate fitted to the rear spars ends at the joint zone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Preferred embodiments of the invention, are henceforth described with reference to the accompanying drawings, wherein:

[0027] FIGS. 1A-1C represents at HTP single central rib concept of the prior art, wherein FIG. 1A is a perspective view of the rear section of an aircraft where the position of the central rib is indicated by an arrow; FIG. 1B is a perspective view of a central rib; and FIG. 1C is a perspective view of a central region of a continuous HTP, showing the arrangement of the single central rib.

[0028] FIG. 2A shows a top plant view of the central region of a HTP torsion box according to the invention, with the upper cover removed to visualize the internal components of the torsion box. FIG. 2B is a perspective view of the same torsion box.

[0029] FIG. 3 shows a perspective view of an enlarged detail of the assembly between the inner-most ribs of the torsion box and the stringers according to the invention.

[0030] FIGS. 4A and 4B show in cross-sectional view, a schematic representation of the assembly mentioned in FIG. 3, for the case of omega-shaped stringers (FIG. 4A), and for T-shaped stringers (FIG. 4B).

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] FIG. 2A shows a preferred embodiment of a horizontal tail plane HTP (1) according to the invention, comprising first and second lateral torsion boxes (2,2′) joined to each other at a central region of the HTP, and symmetrically arranged with respect to the axis of symmetry (X) of the HTP (1). Each of said lateral torsion boxes (2,2′) comprises respectively front and rear spars (3,4,3′,4′), and a plurality of ribs (5,5′) having ends respectively joined to the front and rear spars (3,4,3′,4′). The rear spars (4,4′) are joined to each other at a joint zone (12) located at the rear vertex of the HTP and within the axis of symmetry (X) of the HTP (1).

[0032] According to the invention, the inner-most ribs (11,11′), that is, the ribs closer to the axis of symmetry (X), are arranged as to converge towards said joint zone (12). Therefore, the HTP (1) of the invention has an intersection point at said joint zone (12), wherein both rear spars (4,4′) and the inner-most ribs (11,11′) intersect. In this way, a hard point is formed at that zone where the loads are concentrated.

[0033] In this embodiment, the inner-most ribs (11,11′) are arranged to define a 90° angle with the respective rear spar (4,4′) to which is joined.

[0034] As it can be observed in FIG. 2A, in the HTP (1) of the invention there is no central rib located along the axis of symmetry (X) of the HTP (1). In this way, all the ribs (5,11,5′,11′) of the first and second torsion boxes (2,2′), are positioned to define an angle (α) different than 0° with respect to the axis of symmetry (X) of the horizontal tail plane, or are positioned parallel to the axis of symmetry (X) of the horizontal tail plane. Said angle (α) is formed by the intersection between the axis (X) and a straight line passing along each rib, taking into account that the ribs are generally flat.

[0035] The HTP (1) comprises a reinforcement metallic plate (14) fitted to both rear spars (4,4′) end at the joint zone (12). At the front part of the HTP, a front fitting (6) is provided to receive a trimming actuator (not shown) for the HTP. The inner ends of the front spars (3,3′) are joined to the front fitting (6).

[0036] Conventionally, the first and second lateral torsion boxes (2,2′) comprise a plurality of stringers (13,13′) longitudinally arranged in torsion box shown in FIG. 2A. Since the loads are now concentrated in said hard point, there is no need to extend the stringers towards the central region, thus, some of the stringers, preferably all of them, are terminated at the respective inner-most rib (11,11′) as shown in FIG. 2A. In this manner, an additional weight reduction of the HTP is achieved.

[0037] This arrangement is shown in more detail in FIG. 3, wherein it can be observed that each stringer (13,13′), in this case of the first torsion box (2) and lower skin, has one end located at a plane defined by the inner-most rib (11). The same arrangement is formed at the upper cover of the same torsion box, and equally at the upper and lower covers of the second torsion box (2′).

[0038] Most of the components of the HTP are manufactured with Carbon Fiber Reinforced Plastic (CFRP) materials.

[0039] These stringers (13,13″) can be omega-shaped or T-shaped stringers as shown in FIGS. 4A and 4B, and typically are configured with a run-out section at its end. The inner-most ribs (11,11′), are configured to match with the shape of that run-out section of all the stringers, such as this run-out section is covered by the inner-most rib. Furthermore, the stringers (13,13″) and the respective inner-most rib (11,11′) are co-bonded together.

[0040] It has been observed in FIG. 3 how the end of the stringers coincides with the rib, that is, is covered by the rib. This arrangement improves the performance of the run-out section of the stringers, since any peeling effect at the end of the stringer is avoided thanks to the rib flange which is placed on the end of the stringer.

[0041] FIGS. 4A and 4B show this arrangement in more detail, wherein it can be noted that stringers feet (15), webs (16) and heads (17) in the case of omega stringers stiffened covers (FIG. 4A), or only the feet (15) in the case of T stringers stiffened covers (FIG. 4B), are covered by a part of the respective inner-rib (11,11′).

[0042] The components of the HTP can be integrated in the structure, by riveting, co-curing (if all parts are prepreg), or co-bonding (in a hard/wet prepreg preparation, or in RTM/wet prepreg). Preferably, the ribs already cured are co-bonded (previously cured prepreg or RTM) to wet prepreg ATL omega stringers and skin assembly in a one shot curing cycle, but nevertheless, co-cured and riveted options are feasible. Drawings 4A,4B show the resulting co-bonded interfaces (18) of the parts for the cases of omega and T stringers stiffened covers.

[0043] In some preferred embodiments of the invention and depending on the aircraft type, it might be desirable to slightly increase the center area skin thickness, and/or provide small stiffening elements, in order to compensate the now missing central rib. Preferably, the area of the covers with larger thickness, is provided at the central region of the HTP, and more specifically at the joint zone (12) where the concentration of loads is higher.

[0044] Some of the main advantages of the invention are: the weight, manufacturing and assembly costs reduction, due to the absence of a central rib; improved performance of the stringers run-out sections; provision of a fully integrated one shot continuous HTP torsion box structure.

[0045] The embodiments of the present invention described herein can be combined.

[0046] 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.