What is Aircraft Roll Motion?
Roll is what you call it when the aircraft moves through it’s roll (also longitudinal) axis which lies along the aircraft centerline. It is the up and down movement of the wings of the aircraft.
The rolling motion of the aircraft is being caused by the deflection of the ailerons of the aircraft. The aileron is a hinged section at the rear of each wing. The ailerons work in opposition; when the right aileron goes up, the left aileron goes down.[1]
A stick is connected by means of wires or hydraulics to the wings’ ailerons. By turning the stick, the pilot can change the positions of the ailerons. When the control wheel is turned to the right, the right aileron goes up and the left aileron goes down, rolling to the airplane to the right, and vice versa.
Since the ailerons work in pairs, the lift on one wing increases as the lift on the opposite wing wing decreases. Because the forces are not equal, there is a net twist, or torque about the center of gravity and the aircraft rotates about the roll axis. The pilot can use this ability to bank the aircraft which causes the airplane to turn.[1]
There are other ways to produce a rolling motion on an aircraft. The Wright brothers used a method called wing warping. Their wings were wired together in such a way that the outer panels of each wing could be twisted relative to the inner panel. The twisting changed the local angle of attack of sections of the wing which changed the lift being generated by that section. Unequal forces on the wings caused the aircraft to roll. Many modern airliners use a spoiler to roll the aircraft. A spoiler is a plate that is raised between the leading and trailing edges of the wing. The spoiler effectively changes the shape of the airfoil, disrupts the flow over the wing, and causes a section of the wing to decrease its lift. This produces an unbalanced force with the other wing, which causes the roll. Airliners use spoilers because spoilers can react more quickly than ailerons and require less force to activate, but they always decrease the total amount of lift for the aircraft.[1]
*gif
