A vane actuator arrangement for a rotary engine is described in which the vane is arranged to be rotationally static with respect to the rotor, and to reciprocate radially inwards and outwards such that the radial motion of the vane follows the eccentric rotary motion of the outer peripheral surface of the rotor (4). The vane actuator is configured to maintain the vane at a predetermined seal gap distance (A6) from the peripheral outer surface of the rotor. The vane actuator comprises a radial follower shaft (A3), arranged to translate eccentric rotation of the first rotor shaft into radial reciprocating motion of the follower shaft with respect to the stator chamber (A1), the follower shaft extending radially beyond the peripheral wall of the stator chamber.