A gas turbine engine has a fan rotor including at least one stage, with the at least one stage delivering a portion of air into a low pressure duct, and another portion of air into a compressor. The compressor is driven by a turbine rotor, and the fan rotor is driven by a fan drive turbine. A channel selectively communicates air from the low pressure duct across a boost compressor.

A gas turbine engine has a fan rotor including at least one stage, with the at least one stage delivering a portion of air into a low pressure duct, and another portion of air into a compressor. The compressor is driven by a turbine rotor, and the fan rotor is driven by a fan drive turbine. A channel selectively communicates air from the low pressure duct across a boost compressor.

An air compressing system is provided that includes a compressor configured to compressor air. An engine is operatively connected to the compressor. Further, an infinitely variable transmission is operatively connected between the engine and the compressor. A first shaft operatively connects the engine to the infinitely variable transmission and is configured to rotate at a first speed and a second shaft operatively connects the infinitely variable transmission to the compressor and is configured to rotate at a second speed.

An air compressing system is provided that includes a compressor configured to compressor air. An engine is operatively connected to the compressor. Further, an infinitely variable transmission is operatively connected between the engine and the compressor. A first shaft operatively connects the engine to the infinitely variable transmission and is configured to rotate at a first speed and a second shaft operatively connects the infinitely variable transmission to the compressor and is configured to rotate at a second speed.

A hybrid-electric propulsion system includes a gas turbine engine, an electric machine coupled to and rotatably driven by the gas turbine engine to produce AC electric power, an energy storage system, and a propulsion unit. The gas turbine engine includes a combustor and a recuperator that places an exhaust air flow that is downstream from the combustor in a heat exchange relationship with a compressed air flow that is upstream from the combustor to transfer thermal energy from the exhaust flow to the compressed flow. The propulsion unit includes a fan and an electric motor rotably coupled to the fan, the electric motor being driven by electric power from one of the electric machine or the energy storage system.

A method to reduce aerodynamic drag of a engine exhaust/engine nozzle includes collecting data that is indicative of an instant flight condition, entering the data into a decision algorithm that, based on the data, outputs at least first and second drag control parameters corresponding, respectively, to an angle of one or more variable area turbines of a turbine engine and a position of a variable area exhaust nozzle of the turbine engine, and adjusting the angle of the one or more variable area turbines and the position of the variable area exhaust nozzle according to, respectively, the first and second drag control parameters to reduce aerodynamic drag of an engine exhaust/engine nozzle of the turbine engine.

An airflow control system for a gas turbine according to an embodiment includes: an airflow generation system for attachment to a rotatable shaft of a gas turbine system, the airflow generation system drawing in an excess flow of air through an air intake section; a mixing area for receiving an exhaust gas stream of the gas turbine system; an air extraction system for: extracting at least a portion of the excess flow of air generated by the airflow generation system to provide bypass air; and diverting the bypass air into the mixing area to reduce a temperature of the exhaust gas stream; and an exhaust processing system for processing the reduced temperature exhaust gas stream.

A method of calibrating a gas turbine engine having a propulsive fan, and an engine core, the method including: measuring a total thrust generated by the engine; measuring the thrust generated by the engine core; measuring first and second engine performance parameters; based on the total thrust and engine core thrust, determining a thrust generated by the propulsive fan; providing a first power setting parameter associating the fan thrust with the first engine performance parameter; and providing a second power setting parameter associating the engine core thrust with the second engine performance parameter.

A method of calibrating a gas turbine engine having a propulsive fan, and an engine core, the method including: measuring a total thrust generated by the engine; measuring the thrust generated by the engine core; measuring first and second engine performance parameters; based on the total thrust and engine core thrust, determining a thrust generated by the propulsive fan; providing a first power setting parameter associating the fan thrust with the first engine performance parameter; and providing a second power setting parameter associating the engine core thrust with the second engine performance parameter.

An engine system has a gas generator, a bi-fi wall surrounding at least a portion of the gas generator, a casing surrounding a fan, and the casing having first and second thrust reverser doors which in a deployed position abut each other and the bi-fi wall.