Abstract: A gas turbine engine for an aircraft includes an engine core having a turbine, a compressor, and a core shaft interconnecting the turbine and compressor. A fan with multiple fan blades is positioned upstream of the engine core and is driven at a reduced rotational speed through an epicyclic gearbox coupled to the core shaft. The gearbox includes a sun gear, a plurality of planet gears mounted on a planet carrier, and a ring gear. The planet carrier has an effective linear torsional stiffness, and the gearbox includes defined gear mesh stiffnesses between the planet gears and both the sun and ring gears. The respective stiffness values are selected to provide desired dynamic behavior and vibration characteristics of the gearbox, such that the relationship between the gear mesh stiffnesses contributes to efficient torque transmission, reduced noise, and enhanced durability of the fan drive system.

Abstract: A gas turbine 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 is positioned upstream of the engine core and includes a plurality of fan blades. A gearbox is configured to receive rotational input from the core shaft and to drive the fan at a rotational speed lower than that of the core shaft, thereby defining a gear ratio between the core shaft and the fan. The gearbox has an overall gear mesh stiffness, and the core shaft has an effective linear torsional stiffness. The engine is configured such that a ratio of the overall gear mesh stiffness of the gearbox to the effective linear torsional stiffness of the core shaft is greater than or equal to 0.2.

Abstract: Gearboxes for aircraft gas turbine engines, in particular arrangements for journal bearings such gearboxes, and related methods of operating such gearboxes and gas turbine engines, including a gearbox for an aircraft gas turbine engine, the gearbox including: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.

Abstract: 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.

Abstract: 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 1.20×109 N/m, and/or the tilt stiffness of the planet carrier is greater than or equal to 6.00×108 Nm/rad. A method of operation of such an engine is also disclosed.

Abstract: Gearboxes for aircraft gas turbine engines, in particular to arrangements for journal bearings such gearboxes, and to related methods of operating such gearboxes and gas turbine engines. Example embodiments include a gearbox for an aircraft gas turbine engine, the gearbox including: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a bearing.

Abstract: Gearboxes for aircraft gas turbine engines, in particular to arrangements for journal bearings such gearboxes, and to related methods of operating such gearboxes and gas turbine engines. Example embodiments include a gearbox for an aircraft gas turbine engine, the gearbox including: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a bearing.

Abstract: Gearboxes for aircraft gas turbine engines, in particular to arrangements for journal bearings such gearboxes, and to related methods of operating such gearboxes and gas turbine engines. Example embodiments include a gearbox for an aircraft gas turbine engine, the gearbox including: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a bearing.

Abstract: A composite gear includes an annular metallic gear hub including a bore and defining a central axis. The composite gear includes a composite web disposed circumferentially around the annular metallic gear hub with respect to the central axis. It includes a metallic gear rim disposed circumferentially around the composite web with respect to the central axis. The metallic gear rim includes an annular portion disposed adjacent to the composite web and a plurality of gear teeth angularly spaced apart from each other and extending outwardly from the annular portion distal to the composite web. The composite gear includes an interface disposed between the metallic gear rim and the composite web. The composite web includes a plurality of fibres inclined against each other by an angle from 30 to 60 degrees in order to form a mesh or woven fabric.

Abstract: A gas turbine engine for an aircraft comprising an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor. A fan located upstream of the engine core, the fan comprising a plurality of fan blades and having a fan diameter and a gearbox arranged to receive an input from the core shaft and to output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, thereby defining a gear ratio. The gearbox being an epicyclic gearbox. A gearbox diameter is defined as the pitch circle diameter of the ring gear; and a geared-fan value defined by a product of the fan diameter and gear ratio, which are divided by the gearbox diameter, being greater than 12.

Abstract: Gas turbine engine includes: an engine core including a turbine, compressor, and core shaft connecting the turbine to the compressor; a fan located upstream of the core; and a gearbox that is configured to receive an input from the core shaft, and 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. A fan shaft radial bending stiffness to moment of inertia ratio defined as: a ? radial ? bending ? stiffness ? of the ? fan ? shaft ? at ? the ? ? output ? of ? the ? gearbox the ? moment ? of ? inertia ? of ? the ? fan is in a range from 2.5×10?2 Nkg?1m?1mm?2 to 6.0 Nkg?1m?1 mm?2.

Abstract: Gearboxes for aircraft gas turbine engines, in particular to arrangements for journal bearings such gearboxes, and to related methods of operating such gearboxes and gas turbine engines. Example embodiments include a gearbox for an aircraft gas turbine engine, the gearbox including: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.

Abstract: A gas turbine engine for an aircraft includes an engine core with a turbine, a compressor, and a core shaft connecting the turbine and compressor; a fan upstream of the engine core including a plurality of fan blades; and a gearbox that receives an input from a gearbox input shaft portion of the core shaft and outputs drive to a fan shaft so as to drive the fan at a lower rotational speed than the core shaft, the gearbox being an epicyclic gearbox including a sun gear, a plurality of planet gears, a ring gear, and a planet carrier arranged to have the plurality of planet gears mounted thereon, and wherein the sun gear receives input from the core shaft. At cruise conditions the torque on the core shaft is greater than 10,000 Nm and a ratio of core shaft stiffness to core shaft torque is within a specified range.

Abstract: 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 1.20×109 N/m, and/or the tilt stiffness of the planet carrier is greater than or equal to 6.00×108 Nm/rad. A method of operation of such an engine is also disclosed.

Abstract: Gas turbine engine for aircraft includes: an engine core including a turbine, compressor, and core shaft; a fan located upstream of the core; and a gearbox for receiving input from the core shaft, and outputting drive to a fan shaft via an output of the gearbox. A fan-gearbox axial distance is an axial distance between an axial position of the gearbox output position and the fan axial centreline. The fan-gearbox axial distance multiplied by a moment of inertia of the fan may range from 1.9×107 kgmm2m to 6.2×108 kgmm2m and/or the fan-gearbox axial distance divided by a moment of inertia of the fan may range from 5.3×10?10 m/kgmm2 to 8.8×10?9 m/kgmm2. A product of: (the radial bending stiffness of the fan shaft at the output of the gearbox)×(the moment of inertia of the fan) may be range from 2.0×1014 Nkgmm2m?1 to 1.4×1018 Nkgmm2m?1.

Abstract: Gearboxes for aircraft gas turbine engines, in particular arrangements for journal bearings such gearboxes, and related methods of operating such gearboxes and gas turbine engines. A gearbox for an aircraft gas turbine engine includes: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.

Abstract: A hybrid transmission component includes a composite tube defining a central axis along its length and extending between a first end and a second end opposite to the first end. The composite tube includes a tube inner surface extending circumferentially about the central axis and a tube outer surface that is radially spaced apart from the tube inner surface with respect to the central axis. The composite tube further includes a first tube axial end surface extending between the tube inner surface and the tube outer surface at the first end and a second tube axial end surface extending between the tube inner surface and the tube outer surface at the second end. The tube inner surface comprises a wedge portion disposed at the first end.

Abstract: A composite gear includes an annular metallic gear hub including a bore and defining a central axis. The composite gear includes a composite web disposed circumferentially around the annular metallic gear hub with respect to the central axis. It includes a metallic gear rim disposed circumferentially around the composite web with respect to the central axis. The metallic gear rim includes an annular portion disposed adjacent to the composite web and a plurality of gear teeth angularly spaced apart from each other and extending outwardly from the annular portion distal to the composite web. The composite gear includes an interface disposed between the metallic gear rim and the composite web. The composite web includes a plurality of fibres inclined against each other by an angle from 30 to 60 degrees in order to form a mesh or woven fabric.

Abstract: Gearboxes for aircraft gas turbine engines, in particular arrangements for journal bearings such gearboxes, and related methods of operating such gearboxes and gas turbine engines, including a gearbox for an aircraft gas turbine engine, the gearbox including: a sun gear; a plurality of planet gears surrounding and engaged with the sun gear; and a ring gear surrounding and engaged with the plurality of planet gears, each of the plurality of planet gears being rotatably mounted around a pin of a planet gear carrier with a journal bearing having an internal sliding surface on the planet gear and an external sliding surface on the pin.

Abstract: 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.