This application claims the benefit of the European patent application No. 15382071.1 filed on Feb. 23, 2015, the entire disclosures of which are incorporated herein by way of reference.
This invention relates to the rear pressure bulkhead of commercial aircraft.
As shown in
Curved and flat rear pressure bulkheads 11, see, respectively,
U.S. Pat. No. 5,062,589 describes a rear pressure bulkhead of curved geometry made up with a monolithic composite panel of particular thickness and made of a fiber-mesh, a woven or a fleece-like reinforcement of a particular radius of curvature and preferably made of Kevlar; a possibly thicker edged portion of, preferably, carbon fiber-reinforced material, which possibly matches any taper of the fuselage, and a transition from the calotte shaped part to the edge having a radius of curvature smaller than the particular radius of the calotte shaped partition.
EP 2 098 448 A1 describes a rear pressure bulkhead of curved geometry made of a composite material, comprising three layers: an outer layer and an inner layer symmetrical with one another, which are made of a fiber laminate, and the intermediate layer or core made of a lightweight material. With such a sandwich-type shape, the resulting bulkhead is able to withstand the bending loads coming from the strain and pressurization of the fuselage without having to increase its stiffness by means of using some type of stiffener. The bulkhead comprises a ring that is attached to the ends of the sandwich shape. This ring is split into several parts to facilitate the assembly of the bulkhead made of composite material to the fuselage skin.
While the primary objective of the rear pressure bulkhead is to resist the differential pressures between the pressurized cabin and the unpressurized rear section also play a role in separating the space allocated to both compartments and in that sense both the curved and the flat bulkhead prevents optimal use of space in both compartments.
The invention provides an aircraft fuselage with a rear pressure bulkhead separating a pressurized cabin and an unpressurized rear end section that comprises flat portions forming one or more kinks between them, one of said kinks being contiguous to the rear border of the floor of the pressurized cabin. A flat kinked rear pressure bulkhead contributes to a space optimization of the aircraft due to an increase of the size of the unpressurized rear end section that allows additional space for location of systems that are not allowed in a pressurized area, is easier to manufacture and assemble than a curved rear pressure bulkhead and has a better bending inertia than a flat rear pressure bulkhead.
In an embodiment, the rear pressure bulkhead comprises upper and lower flat portions forming a kink contiguous to the rear border of the floor of the pressurized cabin. Preferably, the upper flat portion is perpendicular to the longitudinal axis of the fuselage and the lower flat portion forms an angle α with the floor of the pressurized cabin comprised between 30-60°.
In an embodiment, the rear pressure bulkhead comprises upper, middle and lower flat portions forming a first kink between the upper and middle flat portions and a second kink between the middle and lower flat portions contiguous to the rear border of the floor of the pressurized cabin. The middle flat portion is disposed in the same plane as the floor of the pressurized cabin so that also serves as a floor of the upper part of the pressurized cabin. Preferably the upper flat portion is perpendicular to the longitudinal axis of the fuselage and the lower flat portion forms an angle β with the floor comprised between 30-60°.
The rear pressure bulkhead can be made with a metallic or composite material.
In an embodiment with composite material, the rear pressure bulkhead comprises sandwich-type panels in the flat portions and monolithic panels in the kinks and the ends.
In another embodiment with composite material, the rear pressure bulkhead is a monolithic panel with stiffening elements in its flat portions.
Other characteristics and advantages of the present invention will be clear from the following detailed description of embodiments illustrative of its object in relation to the attached figures.
In accordance with one embodiment of the present invention,
As shown in
As noted in the Background in reference to
The technical evolution of the rear pressure bulkhead 11 of aircraft fuselages has been oriented by two basic objectives: structural efficiency to support differential pressures at both sides and ease of manufacture. In that sense the basic alternatives considered have been a flat or curved geometry on the one hand and the use of metallic or composite material on the other hand. In general terms it can be said that from a structural point of view the curved bulkheads are more efficient than the flat ones but more difficult to manufacture.
Flat or curved pressure bulkheads (especially the curved) have the drawback that the space in the unpressurized rear section 15 delimited by them does not allow optimum use of the same to shelter systems housed therein which involves its oversizing and thus an increase in weight and drag.
The rear pressure bulkhead 12 proposed by the present invention is a bulkhead formed by flat portions with one or more kinks between them allowing on the one hand to be more effective structurally than a flat bulkhead 11 and, on the other hand, allocating to the unpressurized rear section 15 areas formerly allocated to the pressurized cabin 13 improving the overall distribution of spaces of the aircraft fuselage and thereby reducing the size of the unpressurized rear section 15 and, consequently, the aircraft weight.
This flexibility allows additional space in the unpressurized rear section 15 for location of systems that are not allowed in a pressurized area due to safety reasons. It also allows the use of non-critical systems housed in the unpressurized rear section 15 as additional shielding for blade impacts on aircraft with engines mounted on the rear fuselage.
Comparing
The rear pressure bulkhead 12 can be manufactured with metallic or composite materials.
In the last case, it can be a monolithic or sandwich structure although the preferred option is a mixed structure combining sandwich type panels in the flat portions and monolithic panels on the kinks and ends, such as those shown in
The rear pressure bulkhead 12 can also be, as shown in
Although the present invention has been described in connection with various embodiments, it will be appreciated from the specification that various combinations of elements, variations or improvements therein may be made, and are within the scope of the invention as defined by the appended claims.
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.
Number | Date | Country | Kind |
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15382071.7 | Feb 2015 | EP | regional |