Aircraft engine pylon to wing mounting assembly

Pylon mounting assemblies are provided for mounting an engine (e.g., a turbojet engine) to a wing of an aircraft. The pylon mounting assemblies include an upper pylon connection member, and a lower pylon connection box. The upper pylon connection member and the lower pylon connection box respectively define opposed lower and upper mounting surfaces which establish a mounting plane that slopes downwardly and rearwardly relative to aircraft travel direction. At least one connector assembly connects the upper pylon connection member and a lower pylon connection box to one another at the opposed respective lower and upper mounting surfaces thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This application may be deemed related to copending and commonly owned U.S. application Ser. No. 14/863,941 filed on Sep. 24, 2015, the entire content of which is expressly incorporated hereinto by reference.

FIELD

The embodiments disclosed herein relate generally to assemblies to attach an aircraft engine (e.g., a turbojet engine) to the underside of an aircraft wing by way of an engine mounting pylon.

BACKGROUND

In order to achieve design goals related to reduction of fuel consumption with its associated advantages of thereby reducing emissions of air pollutants and noise, there is a trend in the commercial aviation industry towards the adoption of turbojet engines having improved design criteria. These new generation turbojet (turbofan) engines are however larger and thus heavier than the existing engine models. On the other hand, newly designed wings are being proposed to match the new generation engines with the ultimate goal of achieving further fuel savings, i.e., wings that sustain lower induced drag due to a larger aspect ratio. These new larger aspect ratio wings however exhibit a characteristic that leads to smaller cross sections with reduced stiffness. Both of these factors contribute to the aeroelastic requirements becoming more critical than for the existing generation of commercial jets.

Taking into account the relatively larger weight and size of the new generation of turbojet engines and the fact that they will be installed under the newly designed wings with larger aspect ratio and thus smaller cross sections, the aeroelastic viability thereby becomes highly dependent on the design of the attachment assemblies to attach the engine mounting pylon to the underside of the wing. The existing solutions for the pylon-to-wing attachment cannot provide an appropriate stiffness for the new mass and geometric characteristics of the newer generation of larger turbojet engines that will readily satisfy flutter certification requirements, particularly when the engine pitch mechanisms are critical to ensure proper engine operation.

Thus, if current pylon-to-wing attachment assemblies are to be adopted for the new generation of turbojet engines, it will become necessary to either increase the structural weight of the wing box or change the wing box construction materials (e.g., from traditional metallic alloys to stiffer and more expensive alternatives such as composite systems).

Therefore, what is needed in this art are turbojet engine pylon-to-wing mounting assemblies that will provide sufficient stiffness requirements to accommodate both the new generation of heavier turbojet engines and the larger aspect ratio (smaller cross-section) aircraft wings. It is towards providing such a solution that the embodiments of the invention disclosed herein are directed.

SUMMARY

According to the embodiments disclosed herein, pylon mounting assemblies are provided for mounting an engine to a wing of an aircraft which include an upper pylon connection member, and a lower pylon connection box, wherein the upper pylon connection member and the lower pylon connection box respectively define opposed lower and upper mounting surfaces which establish a mounting plane that slopes downwardly and rearwardly relative to aircraft travel direction. At least one connector assembly connects the upper pylon connection member and a lower pylon connection box to one another at the opposed respective lower and upper mounting surfaces thereof.

In some embodiments, the upper pylon connection member extends forwardly of the wing box of the aircraft wing. Alternatively or additionally, the upper pylon connection member includes an upper surface which is an extension of an upper surface of the aircraft wing. The lower pylon connection box may be embodied so as to define a substantially horizontal surface forwardly of the upper mounting surface thereof.

The one or connector assemblies may frangibly connect the upper pylon connection member and the lower pylon connection box so as to allow separation of the lower pylon connection box from the upper pylon connection member in response to a separatory load in excess of a nominal design load (thereby meeting crashworthiness certification requirements). These frangible connections between the upper pylon connection member and the lower pylon connection box may include an aligned series of opposed pairs of mounting blocks associated with the upper pylon connection member and the lower pylon connection box, and connectors interconnecting the opposed pairs of mounting blocks.

These and other aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.

DETAILED DESCRIPTION

AccompanyingFIG. 1depicts generally an aircraft10having a fuselage10-1and an exemplary wing10-2which is defined by a structural wing box12formed of wing spars12-1extending outwardly from the fuselage10-1and aerodynamically shaped rib elements12-2(seeFIG. 2). An exemplary turbojet engine14is shown attached to the underside of the wing10-2by way of a pylon mounting assembly16according to the invention. It will of course be understood that only the port side wing10-1and port side engine14are shown inFIG. 1but are exemplary to the starboard side wing and engine that are not depicted therein. Thus, the description which follows applies equally to both wings and engines of the aircraft10.

FIG. 2shows the mounting of the aircraft turbojet engine14to the wing box12of the aircraft wing10-1by way of the pylon mounting assembly16according to the invention in greater detail. As is shown, the pylon mounting assembly16is comprised of an upper pylon connection member16-1and a lower pylon box structure16-2connected to one another by forward and aft connector assemblies18-1and18-2, respectively. The upper pylon connection member16-1is most preferably a solid structure (i.e., a solid mass of lightweight metal alloy) attached rigidly to and extending forwardly of the wing box12relative to the aircraft's travel direction (noted by arrow A inFIG. 2). The lower pylon box structure is however preferably formed of interconnected lattice structure of individual longitudinal and latitudinal support members (not shown). In the interests of improved aerodynamics, both the upper pylon connection member16-1and the lower pylon box structure16-2may be covered by a suitable skin structure (not shown), e.g., aluminum alloy sheet.

The upper pylon connection member16-1defines an upper surface16-1aand a lower mounting surface16-1bwhich defines a plane P1sloping downwardly and rearwardly relative to the aircraft's direction of travel (arrow A). The upper mounting surface16-1ais essentially a forward extension of the top surface of the aircraft wing10-1.

The lower pylon box structure16-2includes a substantially planar forward surface16-2adefining a substantially horizontal plane P2and a mounting surface16-2brearwardly thereof which is parallel to the downwardly and rearwardly sloping plane P2. The engine14is dependently connected to the bottom of the lower pylon box structure16-2by means of conventional forward and aft engine mounting devices19a,19b, respectively.

The aft connector assembly18-2is depicted inFIG. 3, it being understood that the description which follows is likewise applicable to the structures associated with the forward connector assembly18-1. As is shown, the connector assembly18-2includes a series of aligned opposed pairs of mounting blocks20a,20bassociated with the upper pylon connection member16-1and the lower pylon box structure16-2, respectively. The mounting blocks20a,20bare in turn connected together by suitable connectors22(e.g., bolts, pins, rods and the like).

The mounting blocks20a,20band connectors22are designed to provide a frangible coupling between the upper pylon connection member16-1and the lower pylon box structure16-2along the mounting plane P1in the event of horizontal loads (FIG. 4) and upwardly vertical loads (FIG. 5) in excess of nominal design loads being encountered. Thus, as is schematically depicted inFIGS. 4 and 5the engine14may be separated from the wing10-1in response to encountering a separatory horizontal load (FIG. 4) and a separatory upward vertical load (FIG. 5) in order to meet crashworthiness requirements of certification.

The structural arrangement of the upper pylon connection member16-1and the lower pylon box structure16-2provides an assembly for attaching the turbojet engine14to the wing box12with improved stiffness. As such, the turbojet engine14may be of the newer generation of engines having a heavier weight while the wing box12may provide a wing10-2of higher aspect ratio without an excessive increase in the overall structural weight. By adopting the embodiment of the invention as described above, countermeasures such as providing flutter mass at the wing tip, structural sizing based on stiffness, or an expensive material change for the wing box (e.g. from metallic to composite) may be avoided.