Abstract: The roll coupling mechanism of a canard missile is analyzed, and wind tunnel experiments were conducted to study the canard roll control authority of canard-configuration missiles installed with fixed- and free-spinning tails. Experimental results showed that canards were ineffective as roll control devices for canard-controlled missiles with fixed-tail, because noticeable reverse roll moments were induced when the canard have roll command deflection. Yet if the tail spins freely, the reverse induced roll moments could be much reduced, allowing the canard to execute the roll control. Thus, the free-spinning tail is an effective means of eliminating roll coupling and permitting the canard to execute roll control.