A method of operating a multi-engine system of a rotorcraft includes, during a cruise flight segment of the rotorcraft, controlling a first engine to provide sufficient power and/or rotor speed demands of the cruise flight segment; and controlling a second engine to by providing a fuel flow to the second engine that is between 70% and 99.5% less than a fuel flow provided to the first engine. A turboshaft engine for a multi-engine system configured to drive a common load is also described.

An engine heater system for heating a diesel engine of a vehicle. The engine heater system including a gas turbine. A heat exchanger communicatively coupled to an exhaust of the gas turbine. An electric generator including connection members to couple to a battery of the vehicle, and a shaft rotatably attached between the gas turbine and the electric generator. The heat exchanger utilizes the exhaust of the gas turbine to keep the diesel engine of the vehicle within a desired temperature range, and the electric generator charges the battery when the gas turbine rotates the shaft.

An engine heater system for heating a diesel engine of a vehicle. The engine heater system including a gas turbine. A heat exchanger communicatively coupled to an exhaust of the gas turbine. An electric generator including connection members to couple to a battery of the vehicle, and a shaft rotatably attached between the gas turbine and the electric generator. The heat exchanger utilizes the exhaust of the gas turbine to keep the diesel engine of the vehicle within a desired temperature range, and the electric generator charges the battery when the gas turbine rotates the shaft.

An engine heater system for heating a diesel engine of a vehicle. The engine heater system including a gas turbine. A heat exchanger communicatively coupled to an exhaust of the gas turbine. An electric generator including connection members to couple to a battery of the vehicle, and a shaft rotatably attached between the gas turbine and the electric generator. The heat exchanger utilizes the exhaust of the gas turbine to keep the diesel engine of the vehicle within a desired temperature range, and the electric generator charges the battery when the gas turbine rotates the shaft.

A compound engine assembly including a common air conduit having an inlet in fluid communication with ambient air, a compressor, at least one internal combustion engine having an inlet in fluid communication with an outlet of the compressor, a turbine section having an inlet in fluid communication with an outlet of the at least one internal combustion engine, the turbine section configured to compound power with the at least one internal combustion engine, and at least one heat exchanger in fluid communication with the common air conduit, each of the at least one heat exchanger configured to circulate a fluid of the engine assembly in heat exchange relationship with an airflow from the common air conduit circulating therethrough. The compressor has an inlet in fluid communication with the common air conduit upstream of the at least one heat exchanger. The internal combustion engine may be a reciprocating engine.

The gas turbine engine can have an engine core; a core output shaft drivable by the engine core; a power output shaft; an auxiliary power shaft; and a reduction gearbox having gears, the gears drivingly connecting the core output shaft to the auxiliary power shaft. The gears can include an epicyclic gearing drivingly connecting the core output shaft and the auxiliary power shaft to the power output shaft. The gas turbine engine can further have a second auxiliary power shaft interconnected to the auxiliary power shaft, the power output shaft, and the core output shaft by the gears.

A method of operating a multi-engine system of a rotorcraft includes, during a cruise flight segment of the rotorcraft, controlling a first engine to provide sufficient power and/or rotor speed demands of the cruise flight segment; and controlling a second engine to by providing a fuel flow to the second engine that is between 70% and 99.5% less than a fuel flow provided to the first engine. A turboshaft engine for a multi-engine system configured to drive a common load is also described.

A propulsion system for an aircraft includes a furcated nozzle that has at least a first duct that extends from a first propulsor to a first trailing end duct opening and a second duct that extends from a second propulsor to a second trailing end duct opening.

A hybrid electric gas turbine engine includes a fan section, a turbine section, a first gas generating core, and a generator assembly. The fan section has a fan. The turbine section has a turbine drivably connected to the fan through a main shaft that extends along a central longitudinal axis. The first gas generating core extends along a first axis that is radially offset from the central longitudinal axis. The generator assembly is drivably connected to the main shaft through a gear assembly.

A method for coupling a first sub-shaft, which has a first turbomachine and a generator connected to a mains supply, to a second sub-shaft, which has a second turbomachine, by means of an overrunning clutch, has the following steps: a) rotating the second sub-shaft with a starting rotational speed which is lower than the rotational speed of the first sub-shaft; b) measuring the mains frequency of the mains supply; c) measuring a differential angle between the first sub-shaft and the second sub-shaft; d) accelerating the second sub-shaft with an acceleration value which is produced using the mains frequency measured in step b), the differential angle and the starting rotational speed, and therefore the overrunning clutch couples the two sub-shafts to each other with a previously determined target coupling angle.