The Boeing Company

Loyd D Jacobs

Belur N Shivashankara

Byron R Spain

Gautam SenGupta

An engine assembly comprising an engine having an unducted propeller mounted in a pusher configuration. The engine is supported by a mounting strut located upstream of the propeller. The trailing edge portion of the strut discharges air through a rearwardly facing slot to diminish discontinuity of airflow moving from the region of the strut to the propeller, so that load variations on the propeller are diminished, and also improves flow of the intersection of the strut and the fuselage.

Mounting assembly for unducted prop engine and method

A method and apparatus for damping the vibration of a reinforced skin structure (e.g., the fuselage of an aircraft) over a wide frequency range (wideband) in order to reduce the vibration and transmitted noise, and improve the sonic fatigue life, of the structure is disclosed. Wide range damping is accomplished by viscoelastically attaching constraining elements, which can be continuous or segmented, to the skin and to the reinforcing members that support the skin. The viscoelastic attachment between the constraining elements and the reinforcing members directly damp the vibrations of the reinforcing members; and, the viscoelastic attachment between the constraining elements and the skin directly damp the vibrations of the skin. Further, the regions of the constraining elements extending between the regions viscoelastically attached to the reinforcing members and to the skin forms a coupling that allows the skin viscoelastic attachment to indirectly damp the vibrations of the reinforcing member and vice versa. Resonant vibrations due to skin bending, torsional and extensional modes (both cylindrical and panel) and reinforcing member bending, torsional, extensional and tuning fork modes, are all damped.

Method and apparatus for wideband vibration damping of reinforced skin

Viscoelastically damped reinforced skin structures wherein a sandwich skin having a relatively thick core is supported by structural elements, such as stringers and frames, are disclosed. In one form (FIG. 1), a main skin (15) is supported by stringers (13) that are in turn supported by frames (11). The skin, stringers and frames are securely attached to one another by any suitable means, such as a bonding adhesive, rivets, bolts, etc. Located between the stringers are core layers (17) formed of honeycomb or foam materials. A first plate (21) overlies each core layer and extends to the flanges of the adjacent stringer. A second plate (25) overlies each adjacent pair of first plates. The core layer is viscoelastically attached (19 and 23a) to the skin and the first plate; and, the first plate is viscoelastically attached (23b, c and 27a, b) to the stringer flanges and to the second plate. Alternatively, a single plate (49, FIG. 3) can overlie the core layers (47) and the stringers (43). In an alternative form of the invention (FIG. 4), the main skin (63) is located between the stringers (65) and the frames (61); and, is securely attached thereto. An outer skin (67) is viscoelastically attached (68a, b and 73) to the stringers (65) and to core layers (69). The core layers (69) are located between the main (63) and outer skin (67, and pairs of adjacent stringers (65). The core layers are also viscoelastically attached (71) to the main skin (63).

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Bellevue, WA, United States of America

Loyd D Jacobs