A highly efficient gas turbine engine is a system wherein the fan of the gas turbine engine is driven from a turbine via a gearbox, such that the fan has a lower rotational speed than the driving turbine, thereby providing efficiency gains. The efficient fan system is mated to a core that has low cooling flow requirements and/or high temperature capability, and which may have particularly low mass for a given power.

A reverse-core turbofan engine including a propulsor section including a fan and a fan-tip turbine configured to deliver air to a core duct, including a first portion, disposed aft of the propulsor section, and direct air aft, toward an inlet of a reverse-core gas generator, and a second portion, configured to receive air from an exit of the gas generator and direct the air forward and radially outward of the propulsor, toward the fan-tip turbine in the propulsor, thereby driving the propulsor.

A reverse-core turbofan engine including a propulsor section including a fan and a fan-tip turbine configured to deliver air to a core duct, including a first portion, disposed aft of the propulsor section, and direct air aft, toward an inlet of a reverse-core gas generator, and a second portion, configured to receive air from an exit of the gas generator and direct the air forward and radially outward of the propulsor, toward the fan-tip turbine in the propulsor, thereby driving the propulsor.

A gas turbine engine that has improved fuel burn provides operability and/or maintenance requirements when installed on an aircraft. The gas turbine engine is provided with a core compressor that includes twelve, thirteen or fourteen rotor stages. The gas turbine engine has a ratio of a core compressor aspect ratio divided by a core compressor pressure ratio is in the range of from 0.03 to 0.09. This results in an optimum balance between installation benefits, operability, maintenance requirements and engine efficiency when the gas turbine engine is installed on an aircraft.

A gas turbine engine that has improved fuel burn provides operability and/or maintenance requirements when installed on an aircraft. The gas turbine engine is provided with a core compressor that includes twelve, thirteen or fourteen rotor stages. The gas turbine engine has a ratio of a core compressor aspect ratio divided by a core compressor pressure ratio is in the range of from 0.03 to 0.09. This results in an optimum balance between installation benefits, operability, maintenance requirements and engine efficiency when the gas turbine engine is installed on an aircraft.

A disclosed fan drive gear system includes a sun gear rotatable about an axis of rotation, a plurality of intermediate gears rotatable about an intermediate gear rotation axis in meshing engagement with the sun gear and a ring gear circumscribing the intermediate gears. A bearing assembly supports at least one of the plurality of intermediate gears and includes a first beam extending in a first direction and a second beam extending from an end of the first beam in a second direction. The bearing surface supported on the second beam such that first and second beams are configured to maintain the bearing surface substantially parallel to the intermediate gear rotation axis during operation.

A disclosed fan drive gear system includes a sun gear rotatable about an axis of rotation, a plurality of intermediate gears rotatable about an intermediate gear rotation axis in meshing engagement with the sun gear and a ring gear circumscribing the intermediate gears. A bearing assembly supports at least one of the plurality of intermediate gears and includes a first beam extending in a first direction and a second beam extending from an end of the first beam in a second direction. The bearing surface supported on the second beam such that first and second beams are configured to maintain the bearing surface substantially parallel to the intermediate gear rotation axis during operation.

A gas turbine engine for an aircraft includes: a fan adjacent the engine air intake, including a plurality of fan blades; downstream of the fan, an engine core including a turbine, a compressor, and a core shaft connecting the turbine and compressor; an engine core housing at least partly encasing the core; a fan case surrounding the fan and defining at least part of a bypass duct radially outside the core; a plurality of outlet guide vanes extending between the engine core housing and an outlet guide vane support region of the case, adjacent an upstream end of the bypass duct; one or more supports extending from the case to the engine core housing, wherein: a first end of the supports fixes to the case at the outlet guide vane support region; a second end of the supports fixes to the engine core housing adjacent an engine core exhaust.

There is provided a propulsion system for an aircraft, the system having a low-fan-pressure-ratio engine configured to be mounted, in a forward over-wing-flow installation, to a wing of the aircraft. The engine has a core, a variable pitch fan, and a nacelle having a nacelle trailing edge with a top-most portion positioned above a wing leading edge. The engine has an L/D ratio of the nacelle in a range of from 0.6 to 1.0, and a fan-pressure-ratio in a range of from 1.10 to 1.30. The forward over-wing-flow installation enables, during all flight phases of the aircraft, a fan flow exhaust to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the wing and under the wing. During a cruise flight phase of the aircraft, the engine minimizes scrubbing drag of the fan flow exhaust to the wing.

A gas turbine engine assembly including a tap that is at a location up stream of the combustor section for drawing a bleed airflow. An exhaust heat exchanger is configured to transfer thermal energy from the exhaust gas flow into the bleed airflow and communicate the heated bleed airflow into the turbine section where it is expanded to drive the turbine section.