 Spoilers are devices that when extended into the airflow over a wing, disrupt the airflow and reduce the amount of lift generated.Many modern aircraft designs, especially jet aircraft, use spoilers in lieu of, or to supplement ailerons, such as the F4 Phantom II and Northrop P-61 Black Widow, which had almost full width flaps (there were very small conventional ailerons at the wingtips as well).All aircraft with dihedral have some form of yaw-roll coupling to promote stability.