Abstract: An aircraft is provided including a boundary layer ingestion fan mounted to an aft end of a fuselage. A stabilizer is mounted to the fuselage and extends between a root portion and a tip portion to define a span-wise length and extends between a leading edge and a trailing edge along the longitudinal direction. The stabilizer defines a line of maximum thickness that corresponds to the thickest cross sectional portion of the stabilizer along the span-wise length of the stabilizer. The line of maximum thickness is closer to the leading edge of the stabilizer proximate the root portion than at the tip portion, resulting in a pressure distribution that draws higher velocity air away from an inlet of the boundary layer ingestion fan.

Abstract: An aircraft is provided including a fuselage that extends along a longitudinal direction between a forward end and an aft end. A boundary layer ingestion fan is mounted to the fuselage at the aft end and is configured for ingesting boundary layer airflow off the surface of the fuselage. The fuselage defines a profile proximate the boundary layer ingestion fan that is optimized for ingesting a maximum amount of boundary layer air and improving propulsive efficiency of the aircraft. More specifically, the fuselage defines a cross sectional profile upstream of the boundary layer ingestion fan that has more cross sectional area in a top half relative to a bottom half as defined relative to a centerline of the boundary layer ingestion fan.

Abstract: An apparatus for attenuating sound waves in a gas turbine engine includes a surface at least partially defining a pathway for airflow and a plurality of fins extending from the surface. The plurality of fins are configured to dissipate heat into the airflow. Each fin of the plurality of fins includes a fin surface. The fin surface is configured to direct the sound waves between the plurality of fins such that the plurality of fins attenuate the sound waves. The plurality of fins are arranged such that spacing between adjacent fins of the plurality of fins facilitates sound attenuation.

Abstract: An air injection assembly for an aircraft is provided. The aircraft includes a fuselage extending between a forward end and an aft end along a longitudinal direction and a boundary layer ingestion fan mounted to the fuselage at the aft end of the fuselage. The air injection assembly includes a plurality of injection ports defined on a surface of the fuselage at a location upstream of the boundary layer ingestion fan. A supplemental airflow is provided through a fluid passageway to the injection ports where it is ejected to displace at least a portion of relatively higher velocity boundary layer airflow. In this manner, the airflow entering boundary layer ingestion fan is more uniform, has less swirl distortion, and has a lower average velocity.

Abstract: An aircraft includes a boundary layer ingestion fan defining a centerline and including a plurality of fan blades rotatable about the centerline. The aircraft also includes a fuselage extending between a forward end and an aft end along a longitudinal direction, the boundary layer ingestion fan positioned within the fuselage at the aft end of the fuselage, the fuselage defining an inlet upstream of the boundary layer ingestion fan extending at least about 180 degrees around the centerline of the boundary layer ingestion fan, the fuselage further defining an exhaust downstream of the boundary layer ingestion fan.

Abstract: An aircraft is provided including a fuselage that extends along a longitudinal direction between a forward end and an aft end. A boundary layer ingestion fan is mounted to the fuselage at the aft end and is configured for ingesting boundary layer airflow off the surface of the fuselage. The fuselage defines a profile proximate the boundary layer ingestion fan that is optimized for ingesting a maximum amount of boundary layer air and improving propulsive efficiency of the aircraft. More specifically, the fuselage defines a cross sectional profile upstream of the boundary layer ingestion fan that has more cross sectional area in a top half relative to a bottom half as defined relative to a centerline of the boundary layer ingestion fan.

Abstract: An aircraft is provided including a fuselage that extends along a longitudinal direction between a forward end and an aft end. A stabilizer assembly and a boundary layer ingestion fan is mounted to the fuselage at the aft end and is configured for ingesting boundary layer airflow off the surface of the fuselage. The stabilizer assembly includes a stabilizer and a root fillet extending between the stabilizer and the fuselage. The root fillet defines a flow directing surface configured for urging a flow of boundary layer air upward along the vertical direction. In addition, an airflow modifying element may protrude from a surface of the fuselage or the root fillet, the airflow modifying element being configured for directing or reducing swirl in the flow of boundary layer air.

Abstract: Noise attenuation structures, such as acoustic liners for gas turbine engines, are provided. For example, an acoustic liner comprises a face sheet, a backing sheet spaced apart from the face sheet, and a plurality of cavities defined between the face and backing sheets. The cavities are defined by cavity walls. A plurality of backing sheet walls extends from the backing sheet toward the face sheet. The backing sheet walls extend adjacent the cavity walls, and the backing sheet is movable with respect to the face sheet such that the cavities have a variable depth. Other embodiments of noise attenuation structures also are provided.

Abstract: An aircraft includes a fuselage extending between a forward end and an aft end; a propulsor mounted to the fuselage at the aft end of the fuselage, the propulsor comprising an outer nacelle, the outer nacelle defining an inlet to the propulsor; and a deployable assembly attached to at least one of the fuselage or the outer nacelle and moveable between a stowed position and an engaged position. The deployable assembly alters an airflow towards the propulsor or into the propulsor through the inlet defined by the outer nacelle when in the engaged position. The propulsor further comprises a tail cone, wherein the outer nacelle defines an exhaust with the tail cone, and wherein the plurality of nacelle panels are movable generally along the axial centerline to a position at least partially aft of the exhaust of the outer nacelle when in the engaged position.

Abstract: A turbofan engine is provided. The turbofan engine includes a nacelle housing including a radially outer wall and a radially inner wall that defines an interior cavity within the nacelle housing. The turbofan engine also includes a fan assembly positioned at least partially within the interior cavity. A flow passage is defined between the radially outer wall and the radially inner wall for channeling a flow of air therethrough. The flow passage is configured to couple a portion of the interior cavity upstream from the fan assembly in flow communication with an ambient environment exterior from the radially outer wall.

Abstract: An aircraft includes a fuselage extending between a forward end and an aft end. The aircraft additionally includes a propulsor mounted to the fuselage at the aft end of the fuselage, the propulsor including an outer nacelle and the outer nacelle defining an inlet. Additionally, the aircraft includes a deployable assembly attached to at least one of the fuselage or the outer nacelle, the deployable assembly movable between a stowed position and an engaged position. The deployable assembly alters an airflow towards the propulsor or into the propulsor through the inlet defined by the outer nacelle when in the engaged position to increase an efficiency of the aft fan and/or of the aircraft.

Abstract: An aircraft is provided including a fuselage extending between a forward end and an aft end. An aft engine is mounted to the aft end of the fuselage and defines a centerline. The aft engine further includes a nacelle having a forward transition duct at the forward end of the nacelle. The forward transition duct also defines a centerline and the centerline of the forward transition duct is angled downward relative to the centerline of the aft engine.

Abstract: An aircraft propulsion system includes a boundary layer ingestion (BLI) fan system disposed at an aft end of an aircraft. The BLI fan system includes a fan that is configured to rotate about an axial centerline of the BLI fan system in a first direction of rotation. The BLI fan system includes blades that are positioned at a first pitch angle configured to rotate with the fan. An electric motor operably coupled with the BLI fan system is configured to change a direction of rotation of the fan to a different, second direction of rotation. An actuator operably coupled with the BLI fan system is configured to change a position of the blades of the fan to be positioned at a different, second pitch angle.

Abstract: An apparatus for attenuating sound waves in a gas turbine engine includes a surface at least partially defining a pathway for airflow and a plurality of fins extending from the surface. The plurality of fins are configured to dissipate heat into the airflow. Each fin of the plurality of fins includes a fin surface. The fin surface is configured to direct the sound waves between the plurality of fins such that the plurality of fins attenuate the sound waves. The plurality of fins are arranged such that spacing between adjacent fins of the plurality of fins facilitates sound attenuation.

Abstract: An apparatus for attenuating sound waves includes a first surface, a second surface opposite the first surface, and at least one opening defined by the second surface. The apparatus also includes a heat exchanger defining a plurality of cooling channels therein and including a plurality of fins. The plurality of cooling channels extend between the first surface and the second surface. The plurality of fins extend from the second surface. The apparatus further includes at least one cavity extending between the first surface and the second surface. The at least one cavity is in flow communication with the at least one opening. The at least one opening and the at least one cavity are configured to attenuate the sound waves. The apparatus also includes at least one passageway extending between the at least one opening and the at least one cavity and positioned between the plurality of cooling channels.

Abstract: An air injection assembly for an aircraft is provided. The aircraft includes a fuselage extending between a forward end and an aft end along a longitudinal direction and a boundary layer ingestion fan mounted to the fuselage at the aft end of the fuselage. The air injection assembly includes a plurality of injection ports defined on a surface of the fuselage at a location upstream of the boundary layer ingestion fan. A supplemental airflow is provided through a fluid passageway to the injection ports where it is ejected to displace at least a portion of relatively higher velocity boundary layer airflow. In this manner, the airflow entering boundary layer ingestion fan is more uniform, has less swirl distortion, and has a lower average velocity.

Abstract: An aircraft is provided including a boundary layer ingestion fan mounted to an aft end of a fuselage. A stabilizer is mounted to the fuselage and extends between a root portion and a tip portion to define a span-wise length and extends between a leading edge and a trailing edge along the longitudinal direction. The stabilizer defines a line of maximum thickness that corresponds to the thickest cross sectional portion of the stabilizer along the span-wise length of the stabilizer. The line of maximum thickness is closer to the leading edge of the stabilizer proximate the root portion than at the tip portion, resulting in a pressure distribution that draws higher velocity air away from an inlet of the boundary layer ingestion fan.

Abstract: An aircraft is provided including a fuselage that extends along a longitudinal direction between a forward end and an aft end. A stabilizer assembly and a boundary layer ingestion fan is mounted to the fuselage at the aft end and is configured for ingesting boundary layer airflow off the surface of the fuselage. The stabilizer assembly includes a stabilizer and a root fillet extending between the stabilizer and the fuselage. The root fillet defines a flow directing surface configured for urging a flow of boundary layer air upward along the vertical direction. In addition, an airflow modifying element may protrude from a surface of the fuselage or the root fillet, the airflow modifying element being configured for directing or reducing swirl in the flow of boundary layer air.

Abstract: An aircraft is provided including a fuselage that extends along a longitudinal direction between a forward end and an aft end. A boundary layer ingestion fan is mounted to the fuselage at the aft end and is configured for ingesting boundary layer airflow off the surface of the fuselage. The fuselage defines a profile proximate the boundary layer ingestion fan that is optimized for ingesting a maximum amount of boundary layer air and improving propulsive efficiency of the aircraft. More specifically, the fuselage defines a cross sectional profile upstream of the boundary layer ingestion fan that has more cross sectional area in a top half relative to a bottom half as defined relative to a centerline of the boundary layer ingestion fan.

Abstract: An aircraft is provided including a fuselage extending between a forward end and an aft end. An aft engine is mounted to the aft end of the fuselage and defines a centerline. The aft engine further includes a nacelle having a forward transition duct at the forward end of the nacelle. The forward transition duct also defines a centerline and the centerline of the forward transition duct is angled downward relative to the centerline of the aft engine.