Moveable wing tip actuation system

A method of operating an aircraft wing having a fixed wing with a tip, a wing tip device rotatably mounted on a hinge at the tip of the fixed wing, and an actuation system for rotating the wing tip device about the hinge, wherein the actuation system comprises a motor, at least one geared rotary actuator arranged to convert rotary motion into a different rotary motion, a clutch for selectively decoupling rotation of the motor from rotation of the at least one geared rotary actuator, and a brake for preventing motion of the at least one geared rotary actuator when the clutch is engaged, wherein the reduction gearbox, the clutch, and the at least one geared rotary actuator are co-linear, and the method comprising operating the actuation system in:

• a driving mode by engaging the clutch and driving the at least one geared rotary actuator with the motor to rotate the wing tip device about the hinge;
• a flapping mode by disengaging the clutch to allow the wing tip device to rotate about the hinge due to forces external to the wing tip device;
• a braked mode corresponding to an angular position of the wing tip device about the hinge in which upper and lower surfaces of the wing tip device form an angle with upper and lower surfaces of the fixed wing;
• and
• a target mode in which the clutch is engaged, the brake is disengaged and the motor actively targets an angular position of the wing tip device about the hinge in which upper and lower surfaces of the wing tip device form an angle with upper and lower surfaces of the fixed wing.

An aircraft wing comprises a fixed wing with a tip, and a wing tip device rotatably mounted on a hinge at the tip of the fixed wing, such that the wing tip device is rotatable about the hinge, and an actuation system for rotating the wing tip device about the hinge, wherein the actuation system comprises a motor, at least one geared rotary actuator, a clutch for selectively decoupling rotation of the motor from rotation of the at least one geared rotary actuator, the at least one geared rotary actuator is driveable by the motor and arranged to convert rotary motion into a different rotary motion and is arranged to rotate the wing tip device relative to the tip of the fixed wing, wherein the reduction gearbox, the clutch, and the at least one geared rotary actuator are co-linear, and

• wherein the aircraft wing is operable in:
• a driving mode by engaging the clutch and driving the at least one geared rotary actuator with the motor to rotate the wing tip device about the hinge;
• a flapping mode by disengaging the clutch to allow the wing tip device to rotate about the hinge due to forces external to the wing tip device;
• a braked mode corresponding to an angular position of the wing tip device about the hinge in which upper and lower surfaces of the wing tip device form an angle with upper and lower surfaces of the fixed wing;
• and
• a target mode in which the clutch is engaged, the brake is disengaged and the motor actively targets an angular position of the wing tip device about the hinge in which upper and lower surfaces of the wing tip device form an angle with upper and lower surfaces of the fixed wing.