Final answer:
Wings have washout to prevent the wingtips from stalling before the wing root, allowing for better control during a stall and improving the distribution of lift, thus reducing induced drag.
Step-by-step explanation:
Wings have washout or wing twist primarily to manage the aerodynamic characteristics and enhance the safety of the aircraft during flight. Washout is a design feature where the angle of incidence of the wing decreases towards the wingtip. This means that the wing root, which is closer to the fuselage, will reach its critical angle of attack and stall before the wingtip does. Consequently, this design ensures that during a stall, the wingtips — which contain the ailerons and retain some control authority — continue to generate lift, allowing the pilot to maintain control over the aircraft and safely recover from the stall.
Washout also contributes to reducing the induced drag by more evenly distributing lift across the span of the wing, which is especially important during maneuvers that increase the angle of attack, such as takeoff and landing. This subtle variation in wing geometry helps pilots to avoid dangerous flight conditions and enhances the overall aerodynamic efficiency of the aircraft.