A geared turbofan engine with at least one compression stage and at least one turbine stage on a high speed shaft, the high speed shaft coupled through a speed reduction gear box to a low speed shaft with a fan and a starter/generator. The low speed shaft is collinear with the high speed shaft but does not rotate within the high speed shaft. The speed reduction gear box is positioned between and mechanically couples the high speed shaft and the low speed shaft, which allows the fan and the integrated starter/generator on the low speed shaft to operate at a lower speed than the high speed shaft.

The present disclosure is directed to an aircraft power generation system including a reverse Brayton cycle system, a gas turbine engine, and a gearbox. The gas turbine engine includes a compressor section, a turbine section, and an engine shaft. The compressor section is arranged in serial flow arrangement with the turbine section. The engine shaft is rotatable with at least a portion of the compressor section and with at least a portion of the turbine section. The reverse Brayton cycle system includes a compressor, a driveshaft, a turbine, and a first exchanger. The driveshaft is rotatable with the compressor or the turbine, and the compressor, the first heat exchanger, and the turbine are in serial flow arrangement. The gearbox is configured to receive mechanical energy from the engine shaft and transmit mechanical energy to the reverse Brayton cycle system through the driveshaft.

The present disclosure is directed to an aircraft power generation system including a reverse Brayton cycle system, a gas turbine engine, and a gearbox. The gas turbine engine includes a compressor section, a turbine section, and an engine shaft. The compressor section is arranged in serial flow arrangement with the turbine section. The engine shaft is rotatable with at least a portion of the compressor section and with at least a portion of the turbine section. The reverse Brayton cycle system includes a compressor, a driveshaft, a turbine, and a first exchanger. The driveshaft is rotatable with the compressor or the turbine, and the compressor, the first heat exchanger, and the turbine are in serial flow arrangement. The gearbox is configured to receive mechanical energy from the engine shaft and transmit mechanical energy to the reverse Brayton cycle system through the driveshaft.

A gas turbine engine for an aircraft has an engine core comprising turbine, compressor, and core shaft connecting the turbine to the compressor, the turbine being the lowest pressure turbine of the engine, and having turbine blades, and the compressor being the lowest pressure compressor of the engine; fan located upstream of the engine core; and gearbox that receives an input from the core shaft and outputs drive to the fan. The engine core further has three bearings arranged to support the core shaft, the three bearings having two rearward bearings located downstream of the leading edge of the lowest pressure turbine blade of the turbine at the root of the blade, and/or, when the turbine comprises four sets of turbine blades, downstream of the trailing edge of a turbine blade of the third set of turbine blades from the front of the turbine, at the root of the blade.

A gas turbine engine for an aircraft has an engine core comprising turbine, compressor, and core shaft connecting the turbine to the compressor, the turbine being the lowest pressure turbine of the engine, and having turbine blades, and the compressor being the lowest pressure compressor of the engine; fan located upstream of the engine core; and gearbox that receives an input from the core shaft and outputs drive to the fan. The engine core further has three bearings arranged to support the core shaft, the three bearings having two rearward bearings located downstream of the leading edge of the lowest pressure turbine blade of the turbine at the root of the blade, and/or, when the turbine comprises four sets of turbine blades, downstream of the trailing edge of a turbine blade of the third set of turbine blades from the front of the turbine, at the root of the blade.

An insert for supplying a fluid to splines of a drive shaft, the insert extending along an axis of rotation, and the insert comprising an insert wall extending along the axis of rotation, a reservoir defined by the insert wall for storing a fluid, an elastically deformable portion, the elastically deformable portion capable of transitioning between an expanded state and an unexpanded state, and wherein the elastically deformable portion is configured to expand to the expanded state in a radial direction with respect to the axis of rotation when the fluid is supplied to the reservoir during rotation of the insert and to contract to the unexpanded state when rotation of the insert and supply of the fluid to the reservoir are ceased.

An insert for supplying a fluid to splines of a drive shaft, the insert comprising an insert wall extending between a first end and a second end of the insert, a chamber surrounding the insert wall for storing a fluid, a piston having a surface configured to be exposed to the fluid, the piston configured to move between a first position and a second position within the chamber, and the piston biased toward the first position, and wherein an increase in supply of the fluid in the chamber causes the piston to move toward the second position and a decrease in supply of the fluid in the chamber causes the piston to move toward the first position.

An hybrid aircraft power plant, has: a gas turbine engine having a high-pressure spool including a high-pressure compressor, a high-pressure turbine, and a high-pressure shaft drivingly engaging the high-pressure turbine to the high-pressure compressor, a low-pressure spool including a low-pressure compressor, a low-pressure turbine, and a low-pressure shaft drivingly engaging the low-pressure turbine to the low-pressure compressor; an electric motor drivingly engaged to the low-pressure shaft; and a torque-transmitting device operatively connected to the HP-shaft and having an engaged configuration in which the torque-transmitting device drivingly engages the electric motor to the high-pressure shaft and a disengaged configuration in which the torque-transmitting device disconnects the electric motor from the high-pressure shaft.

An hybrid aircraft power plant, has: a gas turbine engine having a high-pressure spool including a high-pressure compressor, a high-pressure turbine, and a high-pressure shaft drivingly engaging the high-pressure turbine to the high-pressure compressor, a low-pressure spool including a low-pressure compressor, a low-pressure turbine, and a low-pressure shaft drivingly engaging the low-pressure turbine to the low-pressure compressor; an electric motor drivingly engaged to the low-pressure shaft; and a torque-transmitting device operatively connected to the HP-shaft and having an engaged configuration in which the torque-transmitting device drivingly engages the electric motor to the high-pressure shaft and a disengaged configuration in which the torque-transmitting device disconnects the electric motor from the high-pressure shaft.

A disclosed turbofan engine includes a gas generator section for generating a gas stream flow and a propulsor section for generating propulsive thrust as a mass flow rate of air through a bypass flow path. The propulsor section includes a fan driven by a power turbine through a speed reduction device at a second rotational speed lower than a first rotational speed of the power turbine. An Engine Unit Thrust Parameter (“EUTP”) defined as net engine thrust divided by a product of the mass flow rate of air through the bypass flow path, a tip diameter of the fan and the first rotational speed of the power turbine is between 0.05 and 0.13 during operation of the turbofan engine.