Abstract: A method controls the stroke of three circumferentially spaced apart actuators attached at respective joints to an actuation ring positionable to vector thrust in a gas turbine engine exhaust nozzle. The circumferential angular location of each of the actuator joints is specified. And, the stroke for each of the actuators is independently calculated using the joint locations in response to pitch and yaw commands. The actuators are then operated to effect the respective strokes therefor to position the nozzle. In a preferred embodiment, the angular locations are specified once, and trigonometric functions thereof are calculated and stored in memory. The stored values may then be used subsequently in calculating stroke as the pitch and yaw commands change.

Abstract: A nozzle failsafe nozzle actuating system for an aircraft gas turbine engine variable exhaust nozzle having a plurality of pivotal flaps circumferentially disposed about a nozzle centerline and bounding an exhaust gas flowpath in the nozzle is provided with a number of primary actuators which are operably connected to nozzle flaps for pivoting and setting an attitude of the flaps relative to the centerline and wherein each of the primary actuators is extendable between a fully extended position and a fully retracted position, and a failsafe nozzle actuating actuator for setting the attitude of each of the flaps to a failsafe attitude during a failsafe mode of the nozzle actuating system wherein the failsafe attitude is such that each of the primary actuators is at a partially retracted position between the fully extended and the fully retracted positions.

Abstract: A method and system are used to calibrate a plurality of actuators joined to an actuation ring in a control system for vectoring exhaust flaps in a vectoring nozzle. The actuators include output rods which are positioned to respective first positions at which output stroke is measured. The actuators are repositioned to different second positions, and the output stroke thereof is again measured. The stroke measurement for each of the actuators is calibrated to effect a common linear response between the first and second measurement positions. The calibrated actuators ensure coordinated linear actuation thereof as the output rods are positioned between their minimum and maximum extensions.

Abstract: A method is provided for locking jet engine exhaust nozzle position in a hydraulic system having nozzle actuators connected by a synchronization cable. The synchronization cable engages with a conical brake locking mechanism to prevent cable rotation in the event of a hydraulic failure. The nozzle is locked in position at the time of the hydraulic failure. This prevents a significant decrease in usable thrust.

Abstract: A method for controlling the amount of side load experienced by a gas turbine engine and associated airframe components is provided, where the gas turbine engine includes a thrust vectoring system which deflects thrust at a vector angle away from a centerline thereof. The method includes the steps of calculating engine thrust, calculating a side load vector angle limit as a function of the calculated engine thrust and a side load limit, and limiting the vector angle of the thrust vectoring system to the side load vector angle limit in order to maintain operation of the gas turbine engine within the side load limit.