Abstract: A propulsion system for an aircraft including a plurality of primary engines is provided. The plurality of primary engines includes at least a first primary engine and a second primary engine, each configured for mounting to a respective one of a pair of wings of the aircraft. The propulsion system additionally includes an aft engine configured for mounting at a tail section of the aircraft. The plurality of primary engines are sized to provide an amount of thrust sufficient for the aircraft to takeoff without use of the aft engine, such that the aft engine may be configured as a non-prime reliable engine.

Abstract: A propulsion system for an aircraft is provided having an aft engine configured to be mounted to the aircraft at an aft end of the aircraft. The aft engine includes a fan rotatable about a central axis of the aft engine having a plurality of fan blades. The aft engine also includes a nacelle encircling the plurality of fan blades with one or more structural members extending between the nacelle and the mean line of the aircraft at a location forward of the plurality of fan blades when the aft engine is mounted to the aircraft. The aft engine may increase a net thrust of the aircraft when mounted to the aircraft.

Abstract: An aircraft including a fuselage and an aft engine is provided. The fuselage extends from a forward end of the aircraft towards an aft end of the aircraft. The aft engine is mounted to the fuselage proximate the aft end of the aircraft and includes a fan and a nacelle. The fan is rotatable about a central axis of the aft engine and includes a plurality of fan blades. The nacelle of the aft engine surrounds the plurality of fan blades and defines a bottom portion having a forward end. Additionally, the nacelle defines a curved surface at the forward end of the bottom portion, the curved surface including a reference point where the curved surface defines the smallest radius of curvature. The nacelle further defines a normal reference line extending normal from the reference point. The normal reference line defines an angle with the central axis of the aft engine greater than zero to, e.g., allow for a maximum amount of airflow into the aft engine.

Abstract: A gas turbine engine is provided having a compressor section, a combustion section, and a turbine section. The compressor section includes one or more compressors and the turbine section includes one or more turbines. The one or more compressors and the one or more turbines are each rotatable about a longitudinal centerline of the gas turbine engine. Additionally, a bleed air flowpath is provided extending between an inlet in airflow communication with the compressor section and an outlet. An auxiliary turbine is positioned in airflow communication with the bleed air flowpath for extracting energy from a flow of bleed air through the bleed air flowpath.

Abstract: An airflow injection nozzle for a stage of airflow injection nozzles located in a turbine section of the gas turbine engine is provided. The airflow injection nozzle includes a leading end positioned opposite of a trailing end, as well as a pressure side positioned opposite of a suction side. The airflow injection nozzle includes an opening positioned on the pressure side oriented generally in a flow direction of the gas turbine engine for injecting a flow of bleed air from a compressor section of the gas turbine engine into the turbine section of the gas turbine engine.

Abstract: A gas turbine engine is provided having a compressor section, a combustion section located downstream of the compressor section, and a turbine section located downstream of the combustion section. A structural member extends from the compressor section to the turbine section for strengthening one or more components of the gas turbine engine. The structural member also defines a flowpath extending between an inlet in airflow communication with the compressor section and an outlet in airflow communication with the turbine section. The flowpath is configured to provide bleed air from the compressor section to the turbine section to capture at least a portion of the energy in such bleed air.