Which design characteristic helps to delay stall in wing structures?

Twist in the wing design, often referred to as "washout," is crucial in delaying stall. This design feature reduces the angle of incidence at the wingtip compared to the root, causing the wingtip to stall after the root. By ensuring that the root of the wing remains effective longer, the airplane can maintain more controlled flight characteristics as the angle of attack increases leading up to a stall. This design characteristic allows pilots to retain aileron control even at high angles of attack, promoting safer handling and reducing the likelihood of an uncommanded spin.

Increased surface area can improve lift, but it does not inherently address stall characteristics directly. Extended flaps increase lift at lower speeds but can alter stall behavior in a way that might not effectively delay a stall under all circumstances. A dihedral angle enhances lateral stability but has little effect on stalling characteristics. Therefore, the twist in the wing design is the most directly related feature to delaying stall in wing structures.