A dynamic analysis of the effect of rollerons‐or gyroscopically‐actuated ailerons‐has been conducted for cruciform projectiles. The dynamic stability derivatives are determined from unsteady lifting‐surface solutions. The problem is formulated with two degrees of freedom, which include the body rolling and the rolleron deflection. It is found that the gyroscopic coupling, the inertial coupling and the aerodynamic coupling are all existing between the two motions. The gyroscopic effect basically constitutes a restoring moment while aerodynamic loads provide damping. The effectiveness of the rolleron in improving the damping‐in‐roll characteristic is demonstrated through a numerical example. It is also shown that an optimal design is in general existing.