The present invention discloses an active wing-twist mechanism and a control system, and relates to a wing-twist aircraft having a wing, an actuation system, a sensor, and/or a controller. The wing may have a wingspan that extends to a wing tip. The wing may further include a spar aligned in a span-wise direction, wherein at least one rib is operatively coupled to the spar. The actuation system may be configured to rotate the spar, which, in turn, torsionally rotates (pivots) the at least one rib coupled to the spar, thereby twisting the wing. The sensor may be configured to measure a characteristic of the wing, while the controller may be configured to command the actuation system to rotate the spar based at least in part on input from the sensor.