There is disclosed in one example a tiltrotor system for a vertical takeoff and landing (VTOL) aircraft, including: a rotor pylon, wherein the rotor pylon is rotatable, via a rotation maneuver, between a substantially horizontal orientation and a substantially vertical orientation; a linear actuator disposed to actuate the rotation maneuver; and a mechanical guide disposed to maintain a center of gravity along a substantially linear axis throughout the rotation maneuver.