The F9F-8 Cougar used spoilers for roll control; they had no ailerons. They were nearly full span and just ahead of the trailing edge flaps. The airplane center of the roll was not on the centerline, it was about a point towards the "UP" spoiler. During landing if one was high on the glidepath the airplane could be lowered to the glidepath by alternately rolling left and right. The up spoiler decreased lift on that wing. Spoilers became popular because on some early jets the ailerons instead of inducing roll they caused the wing to bend which resulted in rolling the wrong direction ( aileron reversal ).