An improvement to an aircraft is provided in the form of an aircraft auxiliary power and thrust unit located in the tail cone of the aircraft. The unit includes a turbofan engine, an air intake opening, an inlet duct extending between the air intake opening and the turbofan engine, a transmission assembly, and various auxiliary equipment. The engine includes a forward-facing main turbine shaft. The air intake opening is located in the tail cone at a body station location forward of the engine. The transmission assembly includes a drive shaft mounted axially to the main turbine shaft and extends forward through the inlet duct through a sealed opening in the inlet duct. The auxiliary equipment is also located in the tail cone, forward of the turbofan engine. The transmission assembly is releasably connected to the auxiliary equipment. In a first operating mode, the engine is operated at a low setting to power the auxiliary equipment. In a second operating mode, the turbofan engine is used to provide thrust and operate auxiliary equipment.

Auxiliary power and thrust unit

A convertible aircraft engine, capable of turboshaft and/or turbofan modes of operation, is provided in a configuration that combines certain components to permit variation in bypass flow to match engine airflows with the mode of engine operation. The provided components permit the engine to decrease the power requirements of the engine's forward fan when the engine is operated in the turboshaft mode. To permit a decrease in fan power requirements, the fan is split into an outer portion and an inner portion separated by a rotating shroud. Airflow into the fan's outer portion is controlled with a part span inlet guide vane and an outlet guide vane. The guide vanes can be used to lessen the load on the outer portion of the fan while the inner portion continues to accelerate and compress a normal airflow into an engine compressor for supplying the engine's core. The power normally used to drive the fan outer portion is used instead to power a transfer shaft in the turboshaft mode.

Convertible aircraft engine

A power takeoff for an unducted fan gas turbine engine having first and second counterrotating coaxial rotors coupled respectively to first and second propellers. The rotors and propellers are oriented for rotation about a longitudinal axis of the engine. A gear is coupled to each of the rotors for rotation therewith and arranged to provide rotational motion about an axis transverse to the engine axis. A shaft is coupled to the gear for rotation about the transverse axis. Each of the propellers includes a plurality of propeller blades, each of the blades is rotatable about a corresponding blade axis, and a control is coupled to the blades for varying the pitch thereof whereby power is selectively distributed between the propellers and the power takeoff. The power takeoff may include a propeller coupled to the shaft for developing thrust substantially transverse to the engine axis and/or a pump, compressor, or generator to supply fluids or electric power to other apparatus.

Auxiliary power source in an unducted fan gas turbine engine

A method of powering a rotary-wing aircraft includes selectively coupling and uncoupling a first power turbine to change a power distribution between the rotor system and the secondary propulsion system

Actuation mechanism for a convertible gas turbine propulsion system

An impeller is directly driven by an output shaft of a core engine. The airflow produced by the impeller rotates an air turbine and a fan disposed integrally with the air turbine. The impeller and the air turbine form a fluid coupling which serves also as a speed reducing mechanism. The rotational speed of the fan can be reduced to be lower than that of the output shaft while retaining efficiency of the core engine. The outer diameter of the fan can be increased, raising a bypass ratio.

Turbofan engine including fans with reduced speed

A convertible composite engine capable of either shaft horsepower or thrust generation and split-powered operation in which partial thrust and partial shaft horsepower is generated. The engine is concentric about a single centerline and includes two coaxial free turbines, one driving a load such as by-pass fan and the other a shaft horsepower take-off, such as is commonly used to drive a helicopter rotor drive shaft. A single gas generator provides compressed and heated gases to the coaxial free turbines with the total amount of gases provided determined by the total power required from the two free turbines and the split of gas flow through each free turbine determined by the position of the variable inlet guide vanes at the inlet to each turbine.

Convertible composite engine

A control for a convertible composite engine having variable area inlet free turbines driven by a gas generator so that the composite engine is capable of powering a vehicle, such as a flight vehicle, in more than one mode of operation. The control includes provisions for regulating fuel flow to the gas generator in response to the requirements of one of the free turbines and to position the variable geometry inlet thereto in response to fuel flow and also includes provisions for simultaneously regulating fuel flow to the gas generator in response to the power requirements of the other free turbine and varying the area of the variable geometry inlet thereto in response to fuel flow, and still further includes apparatus for positioning a variable area exhaust nozzle operatively associated with one of the free turbines.

Joseph L. Magri

Papers

Convertible composite engine

Convertible composite engine control