Abstract: An actuation system for rotating a control surface mounted on an aircraft airfoil, the control surface being rotatable about a first axis at an acute angle to the longitudinal axis of the aircraft is disclosed. The invention comprises a first crank having a first end and a second end pivotally mounted to the airfoil and rotatable about a spanwise second axis substantially perpendicular to the longitudinal axis of the aircraft. A second crank is pivotally mounted at its first end to the first crank and is rotatable about a third axis which is substantially perpendicular to the second axis. The second end of the second crank is pivotally mounted to the control surface. The second end of the second crank is rotatable about a fourth axis substantially perpendicular to the second and third axes. An actuator, substantially aligned with the longitudinal axis of the aircraft, is coupled to the airfoil and to the first end of the first crank.