Raytheon Technologies Corporation

Rtx Corporation

Keith B Allyn

Michael E McCune

Marc J Muldoon

Benjamin G Gardell

Jackson David Johnson

An acoustic structure includes at least a pair of adjacent panels. The panels have edges, and the panels define a plurality of cells. A first of the at least a pair of acoustic panels is connected to a second of the pair of acoustic panels at adjacent ones of the edges. There is a pair of spaced faces in each acoustic panel between which the plurality of cells extend. There are openings in each of the edges of each of the adjacent acoustic panels, and between a first of the faces and a second of the faces. A securing member extends through the openings in each of the first and the second of the adjacent acoustic panels. A gas turbine engine is also disclosed.

Joints between acoustic panels

A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A rigid connection between a fan case and an inner core housing includes a plurality of A-frames connected at a connection point to the fan case. Legs in the A-frames extend away from the connection point in opposed circumferential directions to be connected to a compressor wall of the inner core housing. The rigid connection also includes a plurality of fan exit guide vanes rigidly connected to the fan case. A lateral stiffness ratio of the lateral stiffness of the plurality of fan exit guide vanes and a lateral stiffness of a combination of the plurality of A-frame, the compressor wall, and a fan intermediate case which is forward of the low pressure compressor being greater than or equal to 0.6 and less than or equal to 2.0.

Front section stiffness ratio

A gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction. An inner core engine has an inner core engine housing surrounding a compressor section, including a low pressure compressor. A rigid connection between a fan case and the inner core engine includes A-frames rigidly connected at a connection point to the fan case. Fan exit guide vanes rigidly connect to the fan case, and to the inner core engine. A fan intermediate case is positioned forward of a first rotor stage in the low pressure compressor. A rigid structure is connected to the inner core engine and to the fan exit guide vanes. The rigid structure defines a structure moment stiffness. The fan intermediate case defines an intermediate case moment stiffness. A ratio of the structure moment stiffness to the intermediate case moment stiffness is between 5 and 15.

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Rutland, MA, United States of America

Keith B Allyn