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.

The method can include determining a mass flow rate W of working fluid circulating through the compressor stage, determining a control parameter value associated to the geometrical configuration of the variable geometry element based on the determined value of mass flow rate W; and changing the geometrical configuration of the variable geometry element in accordance with the determined control parameter value.

An engine for an aircraft includes an engine core having a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan having a plurality of fan blades; and a gearbox. The gearbox is an epicyclic gearbox and comprises a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted. The radial bending stiffness of the planet carrier is equal to or greater than 1.20×10.sup.9 N/m, and/or the tilt stiffness of the planet carrier is greater than or equal to 6.00×10.sup.8 Nm/rad. A method of operation of such an engine is also disclosed.

An gas turbine engine for an aircraft includes, in axial flow sequence, a compressor module, a combustor module, and a turbine module, together with a first electrical machine rotationally connected to the turbine module. The combustor module has a combustor volume V (cm.sup.3). In use, at a full power condition, the gas turbine engine has a maximum corrected core flow Q (m.sup.3/sec), and a ratio T of:

[00001]$T=\frac{\left(\mathrm{Maximum}\mathrm{Corrected}\mathrm{Core}\mathrm{Flow}=Q\right)}{\left(\mathrm{Combustor}\mathrm{volume}=V\right)}$

is in a range of between 450 and 2,500.

A gas turbine engine for an aircraft comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module. The gas turbine engine further comprises a first electric machine that is rotationally connected to the turbine module, and an electrical energy storage unit. The gas turbine engine is configured to generate a maximum dry thrust T (N). The first electric machine is configured to generate a maximum electrical power P.sub.EM1 (W). The electrical energy storage unit has an energy storage capacity E (Wh), a maximum charge rate C (h.sup.−1), and a maximum discharge rate D (h.sup.−1). The electrical energy storage unit is configured to store electrical energy that may be generated by the first electric machine.

A turbomachine engine can include an unducted fan assembly, an unducted vane assembly, a core engine, a gearbox, and a gearbox efficiency rating. The unducted fan assembly can include a plurality of fan blades. The unducted 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 one or more compressor sections and one or more turbine sections. The gearbox includes an input and an output. The input is coupled to the one or more turbine sections of the core engine and comprises a first rotational speed, the output is coupled to the unducted 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 4.1-14.0. The gearbox efficiency rating is 0.10-1.8.

A gas turbine engine for an aircraft including: an engine core including a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan including a plurality of fan blades; a gearbox that can receive an input from the core shaft, and can output drive to a fan shaft via an output of the gearbox so as to drive the fan at a lower rotational speed than the core shaft; and a fan shaft mounting structure arranged to mount the fan shaft within the engine, the fan shaft mounting structure including at least two supporting bearings connected to the fan shaft. A fan-gearbox axial distance is defined as the axial distance between the output of the gearbox and the fan axial centreline, the fan-gearbox axial distance being greater than or equal to 0.35 m.

A motor controller of the present invention comprises units which obtain information indicative of a motor speed (ω) and information indicative of motor torque (T), an air flow calculation section which calculates an air flow (Q) of a fan based on the motor speed (ω) and the motor torque (T); and a speed command generation section which generates a speed command (ω*) of a motor such that the air flow (Q) coincides with the predetermined air flow command (Q*).

An aircraft gas turbine engine has an engine core having a turbine, compressor, and core shaft connecting the turbine to the compressor, the turbine being the lowest pressure turbine and having a turbine length being the distance between the roots of the most upstream turbine blade at its leading edge and of the most downstream turbine blade trailing edge, and the compressor being the lowest pressure compressor of the engine; a fan located upstream of the engine; and a gearbox receiving an input from the core shaft and outputting drive to the fan. The engine core has three bearings to support the core shaft, the three bearings having a forward bearing and two rearward bearings, with a minor span defined as the distance between the two rearward bearings, and wherein further a minor span to turbine length ratio of: $\frac{\mathrm{minor}\mathrm{span}}{\mathrm{tu}\mathrm{rbine}\mathrm{length}}$
is equal to or less than 1.05.

An engine for an aircraft includes an engine core having a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan having a plurality of fan blades; and a gearbox. The gearbox is an epicyclic gearbox and comprises a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted. The radial bending stiffness of the planet carrier is equal to or greater than 1.20×10.sup.9 N/m, and/or the tilt stiffness of the planet carrier is greater than or equal to 6.00×10.sup.8 Nm/rad. A method of operation of such an engine is also disclosed.