A method and control system for an aircraft engine comprising a gas turbine driving a fan propeller with a mechanical gear-train and a dedicated pitch change mechanism for the fan propeller includes a fuel flow signal input; a pitch change mechanism signal input; a controlled plant for relating a pitch change mechanism pitch angle (BetaP) and a fuel flow (Wf) to at least two controlled outputs and a set of constraints. A decoupling control decoupling the controlled plant and/or the constraints into two separate single-input single-output (SISO) control loops for the first and second controlled outputs and a decoupling control decoupling the constraints from the decoupled controlled outputs and the constraints from one another provide gas turbine and fan propeller coordinate control while coordinately controlling constraints and outputs. A feedforward control can compensate the load change effect on engine speed and fan propeller rotor speed control.

A method and control system for an aircraft engine comprising a gas turbine driving a fan propeller with a mechanical gear-train and a dedicated pitch change mechanism for the fan propeller includes a fuel flow signal input; a pitch change mechanism signal input; a controlled plant for relating a pitch change mechanism pitch angle (BetaP) and a fuel flow (Wf) to at least two controlled outputs and a set of constraints. A decoupling control decoupling the controlled plant and/or the constraints into two separate single-input single-output (SISO) control loops for the first and second controlled outputs and a decoupling control decoupling the constraints from the decoupled controlled outputs and the constraints from one another provide gas turbine and fan propeller coordinate control while coordinately controlling constraints and outputs. A feedforward control can compensate the load change effect on engine speed and fan propeller rotor speed control.

An airfoil for a gas turbine engine including an airfoil body extending between a leading edge and a trailing edge and between a pressure side and a suction side. The airfoil body includes a strut portion extending from the leading edge and a flap portion extending from the trailing edge. The flap portion is pivotable relative to the strut portion. A flexible skin surrounds both the strut portion and the flap portion on both the pressure side and the suction side.

An airfoil for a gas turbine engine including an airfoil body extending between a leading edge and a trailing edge and between a pressure side and a suction side. The airfoil body includes a strut portion extending from the leading edge and a flap portion extending from the trailing edge. The flap portion is pivotable relative to the strut portion. A flexible skin surrounds both the strut portion and the flap portion on both the pressure side and the suction side.

A fan assembly for a gas turbine engine includes a fan disk, a trunnion, an actuation device, a fan blade, and a counterweight assembly. The trunnion is mounted to the fan disk. The actuation device is operably coupled to the trunnion. The fan blade is rotatably attached to the fan disk. The counterweight assembly includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is connected to the trunnion, to the actuation device, or to both. The link arm is configured to drive rotation of the trunnion relative to the fan disk. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and is disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced from the hinge.

A fan assembly for a gas turbine engine includes a fan disk, a trunnion, an actuation device, a fan blade, and a counterweight assembly. The trunnion is mounted to the fan disk. The actuation device is operably coupled to the trunnion. The fan blade is rotatably attached to the fan disk. The counterweight assembly includes a link arm, a lever arm, a hinge, and a counterweight. The link arm is connected to the trunnion, to the actuation device, or to both. The link arm is configured to drive rotation of the trunnion relative to the fan disk. The hinge is pivotably connected to the lever arm. The lever arm is connected to the link arm and is disposed to rotate about a connection point of the lever arm and the hinge. The counterweight is mounted to the lever arm at a location spaced from the hinge.

An aspect includes a method of variable cycle compensation in a gas turbine engine. An electric component can be adjusted to compensate for a power change induced by an actuation system by operating the electric component as an electric motor to compensate for an increase in power absorption or a decrease in power production of a turbomachinery of the gas turbine engine. The actuation system is configured to adjust a variable cycle of the turbomachinery by adjusting power absorption or power production, and the electric component can be configured to add or subtract torque to a shaft of the gas turbine engine. The electric component can be operated as an electric generator to compensate for an increase in power production or a decrease in power absorption of the turbomachinery.

A gas turbine engine comprises a relatively high pressure compressor coupled to a relatively high pressure turbine by a relatively high pressure shaft; a relatively low pressure compressor coupled to a relatively low pressure turbine by a relatively low pressure shaft rotatable independently of the high pressure shaft; a first combustor located downstream of the high pressure compressor and upstream of the high pressure turbine; and a second combustor located downstream of the high pressure turbine, and upstream of the low pressure turbine. The engine further comprises a coupling arrangement configured to selectively transfer torque between the high pressure shaft and the low pressure shaft.

A method and a system for providing in-flight reverse thrust for an aircraft are provided. The aircraft comprises an engine having a rotor, a compressor mechanically coupled to the rotor, and a variable geometry mechanism provided upstream of the compressor and configured to modulate an amount of compression work performed by the compressor. The method comprises operating the rotor with the variable geometry mechanism in a first position, receiving a request to increase reverse thrust for the rotor, in response to the request, adjusting the variable geometry mechanism from the first position towards a second position, the variable geometry mechanism having a greater opening angle in the second position than in the first position, and operating the rotor with the variable geometry mechanism in the second position for causing an increase in the amount of compression work performed by the compressor and an increase in reverse thrust for the rotor.

A method and a system for providing in-flight reverse thrust for an aircraft are provided. The aircraft comprises an engine having a rotor, a compressor mechanically coupled to the rotor, and a variable geometry mechanism provided upstream of the compressor and configured to modulate an amount of compression work performed by the compressor. The method comprises operating the rotor with the variable geometry mechanism in a first position, receiving a request to increase reverse thrust for the rotor, in response to the request, adjusting the variable geometry mechanism from the first position towards a second position, the variable geometry mechanism having a greater opening angle in the second position than in the first position, and operating the rotor with the variable geometry mechanism in the second position for causing an increase in the amount of compression work performed by the compressor and an increase in reverse thrust for the rotor.