RELATED APPLICATION

This application claims priority to European Patent Application 18382441-6, filed Jun. 19, 2018, the entirety of which is incorporated by reference.

FIELD OF THE INVENTION

The present invention refers to a method for manufacturing a rear section of an aircraft, particularly for manufacturing the tail cone and the vertical tail plane of an aircraft at the same time. The present invention also refers to the aircraft rear section manufactured by said method.

BACKGROUND OF THE INVENTION

Conventionally, to build an aircraft fuselage, a series of frames in the shape of the fuselage cross sections are held in position on a rigid fixture. These frames are then joined with the fuselage skin panels that includes lightweight longitudinal elements called stringers that increase the buckling resistance of the skin. The stringers are attached to the skin by means of riveting, by cured resin or by bonding with special adhesives. The junction of the skin panels and the frames is performed by means of angular interface parts called shear ties that joint the frame web and the fuselage skin, to conform the complete fuselage. In some cases, these angular parts can be part of the frame as an integrated flange.

The vertical tail plane, also known as empennage, is conventionally formed by a structural primary torsion box, a leading, a trailing edge and a movable surface. The primary box is formed by a skin, two or more spars and internal ribs. When the number of spars is sufficient, total of part of the ribs could be removed.

In known aircrafts, the junction between the vertical tail plane and the fuselage rear section is an interface of fittings to form the tail cone section. The interface fittings transfer the continuum loads distribution on the skins of the torsion box of the empennage to punctual loads that are transferred to the frames of the fuselage. Frames distribute the load to the fuselage skin.

The loads at the interface fittings are very high because they concentrate on punctual areas of the structure. The high loads requires to significant reinforcements, and the reinforcements add weight to the interface fittings and surrounding elements of the tail cone section. Additionally, the interface fittings need to be covered by aerodynamic fairing that produces significant penalty of aerodynamic drag. In addition, the assembly of these components is time consuming.

SUMMARY OF THE INVENTION

In view of the concerns regarding the conventional interface fittings and time consuming construction of conventional aircraft tail sections, an invention has been made and is disclosed herein which may be embodied as a new assembly of an aircraft empennage including at least the tail cone section and the vertical tail plane (and additionally the horizontal tail plane) with a continuous skin covering the tail cone section and the vertical tail plane.

The invention may include, for certain aircraft configurations with rear fuselage mounted engine, an integrated shield in the vertical tail plane to stop potential debris crossing between engines.

In a discrete interface, some level of failure is required to be considered for safety purposes, so that the overall efficiency of the union is reduced. In contrast to a discrete interface, the invention integrates the tail cone and vertical tail plane.

The invention may be embodied as a method for manufacturing a rear section of an aircraft, for integrating the tail cone and the vertical tail plane with a continuous skin solution, creating a manufacturing method in one shot, so that the operation of joining two major components in final assembly is removed, reducing the costs of assembly.

With the method and aircraft rear section according to the present invention, it is possible to improve on said drawbacks, providing other advantages that are described below.

The invention may be embodied as a method for manufacturing a rear section of an aircraft, said rear section comprising a tail cone and a vertical tail plane, which comprises the following steps:

(i) providing a plurality of pre-cured frames, each pre-cured frame comprising a section of the tail cone and a section of the vertical tail plane;

(ii) providing a plurality of pre-cured stringers;

(iii) placing said plurality of pre-cured stringers in their position in the pre-cured frames;

(iv) placing a skin around the external surface of the pre-cured frames; and

(v) curing the pre-cured frames, the pre-cured stringers, and the skin, forming the final aircraft rear section.

The use of material such as thermoplastic permits several curing cycles.

The curing step may be carried out applying an internal pressure, for example by an expandable chamber placed inside the tail cone sections.

For permitting the disassembly in several parts and a local redesign, the pre-cured stringers are preferably provided in modules.

The curing step may use a mold, wherein said mold is preferably provided with internal modular molds, and also external said mold being made from two mold halves, providing smooth surface on aerodynamic side.

Furthermore, said plurality of pre-cured stringers are preferably placed in their position also in the modular molds.

If necessary, the method for manufacturing a rear section of an aircraft can also comprise a pre-curing step for pre-curing said skin.

The invention may be embodied as an aircraft rear section manufactured with the method as disclosed previously, said aircraft rear section comprising a tail cone and a vertical tail plane, which is characterized in that the aircraft rear section also comprises an external continuous skin that joins the tail cone and the vertical tail plane.

The external continuous skin may be made of a thermoplastic material, even though it could be made from any suitable material.

The method and the aircraft rear section according to the present invention has at least the following advantages:

The loads are not transferred only to discrete points, but the loads transferred are continuously supported by frames and skin.

A transition surface between fuselage conic cylinder and the vertical tail cone profile allows a smooth transition between those surfaces so that the vertical tail cone skin loads can pass directly to the fuselage skin on a continuous manner, not needing to use conventional interface fittings and frames.

The junction of components is easier because of the reduction in number of components and junctions.

Weight reduction because of the removal of the fittings in the tail cone and in the vertical tail plane and the removal of the fairings,

It permits a shielding manufacturing and assembly simplification because of less elements and riveted interfaces in continuous skin concept.

An advantage of the method is to remove or simplify an assembly between two major components typically performed in the last stages of the A/C assembly. At this stage since all parts are produced the capital immobilized is large and any lead time reduction is an important cost saving.

Fairings can be a problem for acoustic fatigue, vibration and debris release in case of engine debris impact. The present invention eliminates this problem because these fairings are reduced.

The continuous skin reduces the punctual load transmitted to the frame. This allows to reduce dimensions constraints on the frames due to the integration of such fittings. As a result, optimization of the frame height and thickness is possible, resulting on a weight reduction.

