Abstract: A self-deploying airfoil mounted on the body of a device such as an artillery shell projectile and folded down and forward with respect to the relative airstream. The airfoil is attached to a yoke by a pivot pin. The yoke shaft is pivoted in the body in a manner to allow it to pivot 90 degrees tangentially with respect to the body. The airfoil assembly may be retained by a cover which is removable to deploy the airfoil. The shaft of the yoke is mounted at a small angle to the axis of the body so that the airfoil has an angle of attack relative to the airstream when it pivots tangentially outward. When the cover is removed, a spring starts the airfoil rotating out into the airstream where drag drives it to the 90 degree position. The yoke is locked in the 90 degree position by a yoke lock pin. The airfoil, which is rigidly attached by pins to the pivot pin, cannot begin to rotate about the pivot pin until the yoke has rotated 90 degrees.