Abstract: An engine core including a turbine, compressor, and a core shaft connecting the turbine and compressor; a fan located upstream of the engine core including a plurality of fan blades; and a gearbox. The gearbox is arranged to receive an input from the core shaft and to output drive to the fan to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and includes a sun gear, a plurality of planet gears, ring gear, and planet carrier to the mounted planet gears. The planet carrier has an effective linear torsional stiffness and the gearbox has a gear mesh stiffness between the planet gears and the ring gear. A carrier to ring mesh ratio of: the ? ? effective ? ? linear ? ? torsional ? ? stiffness ? ? of ? ? the ? ? planet ? ? carrier gear ? ? mesh ? ? stiffness ? ? between ? ? the ? ? planet ? ? gears ? ? and ? ? the ? ? ring ? ? gear is greater than or equal to 0.2.

Abstract: A gas turbine engine (10) for an aircraft comprising: an engine core (11) comprising a turbine (19), a compressor (14), and a core shaft (26) connecting the turbine to the compressor; a fan (23) located upstream of the engine core, the fan comprising a plurality of fan blades; a gearbox (30) that receives an input from the core shaft (26) and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, the gearbox (30) being an epicyclic gearbox (30) comprising a sun gear (28), a plurality of planet gears (32), a ring gear (38), and a planet carrier (34) arranged to have the plurality of planet gears (32) mounted thereon; and a gearbox support (40) arranged to at least partially support the gearbox within the engine. The gearbox (30) has a cross sectional area, the cross sectional area being greater than or equal to 2.

Abstract: Gas turbine engine for aircraft including: engine core including turbine, compressor, and core shaft connecting turbine to compressor; fan located upstream of engine core, including plurality of fan blades; gearbox receives input from core shaft and outputs drive to fan shaft to drive fan at lower rotational speed than core shaft; and fan shaft mounting structure arranged to mount fan shaft within engine. Fan shaft mounting structure includes at least two supporting bearings connected to fan shaft. Gearbox's output is at gearbox output position and fan's input is at fan input position. First bearing separation distance is defined as axial distance between input to fan and closest bearing of at least two supporting bearings in rearward direction from fan.

Abstract: A gas turbine engine for an aircraft has an engine core having a turbine, compressor, and core shaft connecting the turbine and compressor; a fan upstream the engine core, the fan having fan blades; and a gearbox. The gearbox receives an input from a core shaft and outputs drive to a fan to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and has a sun gear, planet gears, ring gear, and planet carrier on which the planet gears are mounted. The gearbox has a gear mesh stiffness between the planet gears and the ring gear and a gear mesh stiffness between the planet gears and the sun gear. The gear mesh stiffness between the planet gears and the ring gear divided by that between the planet gears and the sun gear is in the range from 0.90 to 1.28.

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. 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.

Abstract: An engine for an aircraft has 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 fan blades; and a gearbox. The gearbox receives an input from a core shaft and outputs drive to a fan to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and has a sun gear, planet gears, a ring gear, and a planet carrier on which the planet gears are mounted, the gearbox having an overall gear mesh stiffness. The overall gear mesh stiffness of the gearbox is greater than or equal to 1.05×109 N/m. The gearbox has a gearbox diameter defined as the pitch circle diameter of the ring gear. Optionally, the gearbox diameter is in the range from 0.55 m to 1.2 m.

Abstract: A gas turbine engine including: an engine core including turbine, compressor, and core shaft connecting the turbine to the compressor; a fan; an epicyclic gearbox that: (i) receives input from the core shaft to drive the fan at a lower rotational speed than the core shaft, and (ii) includes a sun gear, ring gear, planet carrier, and planet gears; and a gearbox support. The gearbox has a cross sectional area greater than or equal to 2.4×10?1 m2. A first gearbox support strength ratio of: torsional ? ? strength ? ? of ? ? gearbox ? ? support radial ? ? bending ? ? stiffness ? ? of ? ? gearbox ? ? support ? × cross ? ? sectional ? ? area ? ? of ? ? gearbox is greater than or equal to 7.

Abstract: An engine for an aircraft has 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 for an aircraft is arranged to receive an input from a core shaft and to output drive to a fan so as to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and has a sun gear, a plurality of planet gears, a ring gear, and a planet carrier having a plurality of pins, each pin being arranged to have a planet gear of the plurality of planet gears mounted thereon. A ratio of planet carrier torsional stiffness to pin stiffness is within a specified range.

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: An engine for an aircraft has 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 for an aircraft is arranged to receive an input from a core shaft and to output drive to a fan so as to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and has a sun gear, a plurality of planet gears, a ring gear, and a planet carrier having a plurality of pins, each pin being arranged to have a planet gear of the plurality of planet gears mounted thereon. A ratio of planet carrier torsional stiffness to pin stiffness is within a specified range.

Abstract: An engine for an aircraft includes 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 comprising a plurality of fan blades; and a gearbox. The gearbox receives an input from a gearbox input shaft portion of the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox including a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted. The carrier and the gearbox input shaft each have a torsional stiffness, and a carrier to gearbox input shaft torsional stiffness ratio is greater than or equal to 70.

Abstract: A gas turbine engine includes an engine core, a fan and a gearbox interconnecting the engine core and the fan. The engine core is configured to drive rotation of at least one shaft. The power gearbox is configured to transfer torque from the at least one shaft to an output shaft at a reduced rotational speed. The output shaft is coupled to the fan to drive the fan at the reduced speed and provide trust for the gas turbine engine.

Abstract: A gas turbine engine includes an engine core, a fan and a gearbox interconnecting the engine core and the fan. The engine core is configured to drive rotation of at least one shaft. The power gearbox is configured to transfer torque from the at least one shaft to an output shaft at a reduced rate. The output shaft is coupled to the fan to drive the fan at the reduced rate and provide trust for the gas turbine engine.

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 output drive to the fan so as to drive the fan at a lower rotational speed than the core shaft; and a gearbox support arranged to at least partially support the gearbox within the engine. A flight cycle ratio of: the ? ? torsional ? ? shear ? ? stress ? ? of ? ? the ? ? gearbox ? ? support ? ? at maximum ? ? takeoff ? ? conditions the ? ? torsional ? ? shear ? ? stress ? ? of ? ? the ? ? gearbox ? ? support ? ? at cruise ? ? conditions is less than or equal to 3.20. A method of operating the gas turbine engine is also disclosed.

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 receives an input from the core shaft and outputs 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.

Abstract: A gas turbine engine 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; a fan shaft mounting structure that includes supporting bearings connected to the fan shaft; and an epicyclic gearbox that can receive input from the core shaft, and output drive to the fan shaft so as to drive the fan at a lower rotational speed than the core shaft. The gearbox includes a sun gear, planet gears, a ring gear, and a planet carrier for mounting the planet gears. A torsional stiffness of the planet carrier is greater than or equal to 1.6×108 Nm/rad. The fan shaft mounting structure has: a radial bending stiffness greater than or equal to 7.00×108 N/m, and/or a tilt stiffness greater than or equal to 1.50×107 Nm/rad.

Abstract: A gas turbine engine includes: an engine core with a turbine, compressor, and core shaft; a fan upstream the engine core; a gearbox that can receive an input from the core shaft and output drive to a fan shaft to drive the fan at a lower rotational speed than the core shaft. A fan-gearbox axial distance is greater than or equal to 0.35 m. The fan shaft has: (i) a radial bending stiffness ratio of a radial bending stiffness of the fan shaft at the fan input to a radial bending stiffness of the fan shaft at the gearbox output that is greater than or equal to 6.0×10?3; and/or (ii) a tilt stiffness ratio of a tilt stiffness of the fan shaft at the fan input to a tilt stiffness of the fan shaft at the gearbox output that is greater than or equal to 2.5×10?2.

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; a fan shaft; a gearbox that receives an input from the core shaft and outputs drive to the fan via the fan shaft so as to drive the fan at a lower rotational speed than the core shaft, the gearbox being an epicyclic gearbox having a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted; and a gearbox support arranged to mount the gearbox within the engine. The fan shaft, core shaft, gearbox and the gearbox support together may form a transmission.

Abstract: A planetary gearing includes a sun gear; a plurality of planet gears, a ring gear; and a plurality of planet pins, wherein respectively one planet pin is arranged inside a planet gear, and the planet pin and the planet gear form a lubricated journal bearing. The planet pin includes an axial bore and an inner surface that comprises an axially forward end and an axially rearward end. The inner diameter of the axial bore of the planet pin varies between the axially forward end and the axially rearward end of the inner surface and has a maximum at least at one axial end. The planet pins respectively form a crowning at their abutment surface such that their outer diameter decreases from a maximum outer diameter towards at least an axial end of the abutment surface, and has a minimum at the axial end.

Abstract: A gas turbine engine for an aircraft has an engine core having a turbine, compressor, and core shaft connecting the turbine and compressor; a fan upstream the engine core, the fan having fan blades; and a gearbox. The gearbox receives an input from a core shaft and outputs drive to a fan to drive the fan at a lower rotational speed than the core shaft. The gearbox is an epicyclic gearbox and has a sun gear, planet gears, ring gear, and planet carrier on which the planet gears are mounted. The gearbox has a gear mesh stiffness between the planet gears and the ring gear and a gear mesh stiffness between the planet gears and the sun gear. The gear mesh stiffness between the planet gears and the ring gear divided by that between the planet gears and the sun gear is in the range from 0.90 to 1.28.