Why is washing out a wing performed?

Washing out a wing, which refers to the technique of reducing the angle of incidence from root to tip, is primarily performed to improve the stall characteristics of the wing. By altering the angle of incidence along the length of the wing, it ensures that the root section experiences stalling before the tip section does. This design feature helps maintain aileron effectiveness during a stall, allowing the pilot to retain control and reducing the likelihood of an uncontrolled roll. This is particularly important in aircraft to enhance safety and handling characteristics, especially at lower airspeeds.

In contrast, while decreasing drag, enhancing fuel efficiency, and increasing lift at higher speeds can be important considerations in wing design, they are not the primary reasons for implementing washout. The focus on stall characteristics directly addresses pilot safety and performance rather than efficiency or drag reduction.