Abstract: A novel configuration for an axial flow gas turbine engine for aircraft has an engine core having a core length and including a first turbine, an axial compressor, and a drive connecting the first turbine to the axial compressor, the engine core further including a second turbine, and a fan shaft connecting the second turbine to a fan located upstream of the engine core, the fan including a plurality of fan blades extending from a fan hub, the fan having a tip radius from 90 mm to 225 mm and wherein the ratio of fan tip radius to an engine length is 0.15 to 0.25. The engine may have 3, 4 or 5 compressor stages and combustor volume (in litres) which when divided by fan tip radius (in mm) is 0.015 to 0.083. The fan may be multistage fan configured to permit an electric motor to be located within fan hub diameter.

Abstract: A novel configuration for axial flow gas turbine engine for aircraft has an engine core having a core length and including first turbine, axial compressor, and drive connecting the first turbine to the axial compressor, the engine core further including a second turbine, and a fan shaft connecting the second turbine to a fan located upstream of the engine core, the fan including a plurality of fan blades extending from a fan hub, the fan having a tip radius from 90 mm to 225 mm and wherein the ratio of fan tip radius to an engine length is 0.15 to 0.25. The engine may have 3, 4 or 5 compressor stages and a combustor volume (in litres) which when divided by the fan tip radius (in mm) is 0.015 to 0.083. The fan may be a multistage fan configured to permit an electric motor to be located within the fan hub diameter.

Abstract: A novel configuration for an axial flow gas turbine engine for an aircraft has an engine core having a core length and including a first turbine, an axial compressor, and a drive connecting the first turbine to the axial compressor, the engine core further including a second turbine, and a fan shaft connecting the second turbine to a fan located upstream of engine core, the fan including a plurality of fan blades extending from a fan hub, the fan having a tip radius from 90 mm to 225 mm and wherein the ratio of fan tip radius to engine length is 0.15 to 0.25. The engine may have 3, 4 or 5 compressor stages and a combustor volume (in litres) which when divided by the fan tip radius (in mm) is 0.015 to 0.083. The fan may be multistage fan configured to permit electric motor to be located within fan hub diameter.

Abstract: An aircraft gas turbine engine (10) comprises a main engine shaft (22) arranged to couple a turbine (17) and a compressor (13), the main engine shaft (22) defining an axial direction (9). The gas turbine engine (10) further comprises at least one radially extending offtake shaft (27) coupled to the main engine shaft (22), and a radially extending electric machine (25a, 25b) coupled to the radially extending offtake shaft (22).

Abstract: An aircraft gas turbine engine (10) comprises a main engine spool (22) and a bearing arrangement (36) configured to rotatably support the main engine spool (22). The bearing arrangement (36) includes a damper (41) comprising a static element (42) and a moveable element (39). The gas turbine engine further comprises an electric machine (30) comprising a rotor (34) and a stator (32). The rotor (34) is mounted to the main engine spool (22), and the stator (32) is mounted to the moveable element (39) of the damper to be moveable with the moveable element (39).

Abstract: An aircraft gas turbine engine (10) comprises a main engine shaft (22) arranged to couple a turbine (17) and a compressor (13), the main engine shaft (22) defining an axial direction (9). The gas turbine engine (10) further comprises at least one radially extending offtake shaft (27) coupled to the main engine shaft (22), and a radially extending electric machine (25a, 25b) coupled to the radially extending offtake shaft (22).

Abstract: An aircraft gas turbine engine (10) comprises a main engine spool (22) and a bearing arrangement (36) configured to rotatably support the main engine spool (22). The bearing arrangement (36) includes a damper (41) comprising a static element (42) and a moveable element (39). The gas turbine engine further comprises an electric machine (30) comprising a rotor (34) and a stator (32). The rotor (34) is mounted to the main engine spool (22), and the stator (32) is mounted to the moveable element (39) of the damper to be moveable with the moveable element (39).

Abstract: A gas turbine engine includes a gearbox including a sun gear, annulus gear, plurality of planet gears and a planet gear carrier. Each planet gear is rotatably mounted in the planet gear carrier by a planet gear bearing. A lubrication system is arranged to supply lubricant to the planet gear bearings and at least one of the sun gear, the planet gears and the annulus gears. The planet gear carrier includes an annular extension. The lubrication system includes an annular member arranged around annular extension to define an annular chamber which is sealed at its ends to the planet gear carrier and which contains a reserve of lubricant. The annular member has an inlet to supply lubricant into the annular chamber and the planet carrier has a first passage to supply lubricant to the sun, planet or annulus gear and a second passage to supply lubricant to planet gear bearings.

Abstract: A planetary gear box assembly, comprises a sun gear and a plurality of planet gears in meshing engagement with the sun gear; the planet gears in meshing engagement with a ring gear which encircles the plurality of planet gears, each planet gear mounted for rotation in a planet carrier by means of a bearing pin wherein a bore in the planet carrier for receiving the bearing pin is parallel. The bearing pin includes a small axially tapered section adjacent one or both ends and the assembly further comprises a tapered sleeve configured to interference fit between a radially inner wall surface of the parallel bore and a radially outer surface of the or each axially tapered section.

Abstract: Described is a planet carrier rotatable about a carrier axis, comprising: a planet pin for receiving a planet gear, the planet pin having a body with an external surface for receiving a planet gear bearing or planet gear; a carrier having a first axial wall and a second axial wall with the planet pin extending there between along a planet pin axis, wherein each carrier wall includes a planet pin retention feature located on radially inwards of the planet pin axis and engaged with a portion of the planet pin.

Abstract: A transmission system for transmitting a change of speed between two rotating shafts, includes a planetary gear box having a sun gear arranged for rotation with a first shaft travelling at a first speed. Planet gears contained within a ring gear are arranged to orbit the sun gear when the sun gear rotates and the ring gear is in a fixed position. Each planet gear is mounted for rotation on a centrifugal carrier. An output carrier includes a body having arms and the arms are each aligned with an axis of rotation of a planet gear and held to the centrifugal carrier by one or more supports extending in a radial plane. An output shaft extends from the body in coaxial alignment with the input shaft. A connector which is stiff in a radial dimension but flexible under torsional load is arranged between the output carrier and the centrifugal carrier.

Abstract: A planetary gear box assembly, comprises a sun gear and a plurality of planet gears in meshing engagement with the sun gear; the planet gears in meshing engagement with a ring gear which encircles the plurality of planet gears, each planet gear mounted for rotation in a planet carrier by means of a bearing pin wherein a bore in the planet carrier for receiving the bearing pin is parallel. The bearing pin includes a small axially tapered section adjacent one or both ends and the assembly further comprises a tapered sleeve configured to interference fit between a radially inner wall surface of the parallel bore and a radially outer surface of the or each axially tapered section.

Abstract: Described is a planet carrier rotatable about a carrier axis, comprising: a planet pin for receiving a planet gear, the planet pin having a body with an external surface for receiving a planet gear bearing or planet gear; a carrier having a first axial wall and a second axial wall with the planet pin extending there between along a planet pin axis, wherein each carrier wall includes a planet pin retention feature located on radially inwards of the planet pin axis and engaged with a portion of the planet pin.

Abstract: A transmission system for transmitting a change of speed between two rotating shafts, includes a planetary gear box having a sun gear arranged for rotation with a first shaft travelling at a first speed. Planet gears contained within a ring gear are arranged to orbit the sun gear when the sun gear rotates and the ring gear is in a fixed position. Each planet gear is mounted for rotation on a centrifugal carrier. An output carrier includes a body having arms and the arms are each aligned with an axis of rotation of a planet gear and held to the centrifugal carrier by one or more supports extending in a radial plane. An output shaft extends from the body in coaxial alignment with the input shaft. A connector which is stiff in a radial dimension but flexible under torsional load is arranged between the output carrier and the centrifugal carrier.

Abstract: A gas turbine engine includes a gearbox including a sun gear, annulus gear, plurality of planet gears and a planet gear carrier. Each planet gear is rotatably mounted in the planet gear carrier by a planet gear bearing. A lubrication system is arranged to supply lubricant to the planet gear bearings and at least one of the sun gear, the planet gears and the annulus gears. The planet gear carrier includes an annular extension. The lubrication system includes an annular member arranged around annular extension to define an annular chamber which is sealed at its ends to the planet gear carrier and which contains a reserve of lubricant. The annular member has an inlet to supply lubricant into the annular chamber and the planet carrier has a first passage to supply lubricant to the sun, planet or annulus gear and a second passage to supply lubricant to planet gear bearings.