A turbomachine module with a longitudinal axis comprising an unducted propeller rotated about the longitudinal axis and at least one straightener. The module includes a plurality of unducted variable-pitch stator blades extending along a radial axis, perpendicular to the longitudinal axis, from a fixed casing. The module includes a first stator blade pitch-changing system. The pitch-changing system includes at least one first control that includes a first fixed body connected to the fixed casing and a first body which is axially mobile in relation to the first fixed body and at least one first joining mechanism joining each stator blade to the first mobile body of the first control. The first joining mechanism includes: a joining ring centered on the longitudinal axis, joined to the feet of each stator blade and at least one lever joined, on one hand, to the joining ring and, on the other hand, to the first mobile body of the first control.

A gas turbine engine defining a centerline and a circumferential direction, the gas turbine engine including: a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the turbomachine defining a working gas flowpath and a fan duct flowpath; a primary fan driven by the turbomachine defining a primary fan tip radius R.sub.1 and a primary fan hub radius R.sub.2; a secondary fan located downstream of the primary fan and driven by the turbomachine, at least a portion of an airflow from the primary fan configured to bypass the secondary fan, the secondary fan defining a secondary fan tip radius R.sub.3 and a secondary fan hub radius R.sub.4, wherein the secondary fan is configured to provide a fan duct airflow through the fan duct flowpath during operation to generate a fan duct thrust, wherein the fan duct thrust is equal to % Fn.sub.3S of a total engine thrust during operation of the gas turbine engine at a rated speed during standard day operating conditions; wherein a ratio of R.sub.1 to R.sub.3 equals

[00001]$\sqrt{\left(EFP\right)\frac{\left(1-{{\mathrm{RqR}}_{\mathrm{Sec}.-\mathrm{Fan}}}^2\right)}{\left(1-{{\mathrm{RqR}}_{\mathrm{Prim}.-\mathrm{Fan}}}^2\right)}\left(\frac{1}{\%{\mathrm{Fn}}_{3s}}-1\right)};$ wherein EFP is between 1.5 and 11, wherein RqR.sub.Prim.-Fan is a ratio of R.sub.1 to R.sub.2, and wherein RqR.sub.Sec.-Fan is a ratio of R.sub.3 to R.sub.4.

A propulsion system is provided including an unducted rotating fan defining a fan axis; and a turbomachine disposed downstream from the unducted rotating fan, wherein the turbomachine defines a working gas flowpath flowing therethrough; wherein the propulsion system defines a third stream flowpath and an inlet passage having an inlet that is offset from the fan axis, wherein the inlet passage is configured to provide an inlet airflow to the working gas flowpath, and wherein the third stream flowpath bypasses at least a portion of the turbomachine.

An electronic controller for an engine and a propeller, a control system and related methods are described herein. The control system comprises the controller having a first channel and a second channel independent from and redundant to the first channel. Each channel comprises a control processor configured to receive first engine and propeller parameters and to output, based on the first engine and propeller parameters, at least one engine control command and at least one propeller control command. Each channel also comprises a protection processor configured to receive second engine and propeller parameters and to output, based on the second engine and propeller parameters, at least one engine protection command and at least one propeller protection command. The control system comprises sensors for measuring the parameters of the engine and/or the propeller and effectors configured to control the engine and the propeller.

An apparatus is provided for a gas turbine engine. This gas turbine engine apparatus includes a shaft base, a flange and a plurality of lobes. The shaft base extends axially along an axis between a shaft first end and a shaft second end. The flange is connected to the shaft base at the shaft first end. The flange projects radially out from the shaft base. The flange includes a plurality of fastener apertures, and the fastener apertures include a first fastener aperture. The lobes are arranged circumferentially about the axis. Each of the lobes is connected to and projects radially away from the shaft base. Each of the lobes is connected to and projects axially out from the flange. The lobes include a first lobe and a second lobe. The first fastener aperture is arranged circumferentially between the first lobe and the second lobe. The second lobe radially overlaps the first fastener aperture.

A gas turbine engine defining a centerline and a circumferential direction, the gas turbine engine including: a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the turbomachine defining a working gas flowpath and a fan duct flowpath; a primary fan driven by the turbomachine defining a primary fan tip radius R.sub.1 and a primary fan hub radius R.sub.2; a secondary fan located downstream of the primary fan and driven by the turbomachine, at least a portion of an airflow from the primary fan configured to bypass the secondary fan, the secondary fan defining a secondary fan tip radius R.sub.3 and a secondary fan hub radius R.sub.4, wherein the secondary fan is configured to provide a fan duct airflow through the fan duct flowpath during operation to generate a fan duct thrust, wherein the fan duct thrust is equal to %Fn.sub.3S of a total engine thrust during operation of the gas turbine engine at a rated speed during standard day operating conditions; wherein a ratio of R.sub.1 to R.sub.3 equals

[00001]$\sqrt{\left(EFP\right)\frac{\left(1-Rq{R}_{sec.-Fan}{}^2\right)}{\left(1-Rq{R}_{Prim.-Fan}{}^2\right)}\left(\frac{1}{\%F{n}_{3s}}-1\right)};$

wherein EFP is between 1.5 and 11, wherein RqRp.sub.rim.-Fan is a ratio of R.sub.1 to R.sub.2, and wherein RqR.sub.Sec.-Fan is a ratio of R.sub.3 to R.sub.4.

Apparatuses and systems are provided herein for unducted propulsion systems. The system includes a forward housing for high efficiency for high subsonic sustained flight. A plurality of blades are affixed to the forward housing, wherein the forward housing defines a flowpath curve extending from the forward-most end of the forward housing through the axial extent of a forward blade root. The flowpath curve is described by an axial direction parallel to an axis of rotation and a radius from the axis of rotation. The flowpath curve includes a first point having a first radius where the radius reaches a maximum forward of the forward blade root and a second point aft of the first point having a second radius where the radius stops decreasing. The ratio of the first radius to the second radius is greater than or equal to 1.029.

An engine comprises a first power input and a second power input, a main load, and a transmission engaged with the first power input, the second power input, and the main load. An epicyclic gear train is engaged with the first power input and the main load. A brake in a drive condition engages with the epicyclic gear train to transfer power from the first power input to the main load. The brake in a start condition disengages from the epicyclic gear train to decouple the first power input from the main load. A start assist motor is engaged with part of the transmission separate from the epicyclic gear train. The start assist motor in the start condition rotates the main load to initiate start up of the engine, and in the drive condition prevents transferring power to the main load.

A three-stream gas turbine engine with an embedded electric machine and methods of operating the same are disclosed. In one aspect, a three-stream engine includes an electric machine operatively coupled with a shaft of the engine. The three-stream engine also includes a core engine and a primary fan and a mid-fan positioned upstream of the core engine. The primary fan and the mid-fan are operatively coupled with the shaft. During operation, the three-stream engine defines a tip speed ratio being defined by a tip speed of a rotor of the electric machine to a tip speed of a mid-fan blade of the mid-fan. The tip speed ratio is defined as being equal to or greater than 0.2 and less than or equal to 1.0.

A turbomachine engine can include a fan assembly, a vane assembly, a core engine, a gearbox, and an overall engine efficiency rating. The fan assembly can include a plurality of fan blades. The vane assembly can include a plurality of vanes, and the vanes can, in some instances, be disposed aft of the fan blades. The core engine can include a low-pressure turbine. The gearbox includes an input and an output. The input of the gearbox is coupled to the low-pressure turbine of the core engine and comprises a first rotational speed, the output of the gearbox is coupled to the fan assembly and has a second rotational speed, and a gear ratio of the first rotational speed to the second rotational speed is within a range of 3.2-4.0. The overall engine efficiency rating is within a range of 0.57-8.0.