The plurality of movable fins includes at least a first movable fin coupled to the actuator and a second movable fin coupled to the first movable fin via a time difference link. The time difference link does not interlock the second movable fin with respect to the first movable fin while the first movable fin rotates from the closed position to the predetermined intermediate position, and interlocks the second movable fin with respect to the first movable fin while the first movable fin rotates from the intermediate position to the open position.