What property of skin or covering contributes to the monocoque design's strength?

The correct answer is structural rigidity. In a monocoque design, the skin or covering of the structure plays a critical role in distributing loads and providing strength without the need for a separate internal framework. This design uses the outer surface to bear the stresses, making structural rigidity a vital property.

Structural rigidity allows the covering to maintain its shape and resist deformation under various loads. When the skin is rigid, it effectively contributes to the overall strength of the structure by ensuring that stress is distributed evenly across its surface. This is particularly important in aviation and automotive applications, where both weight reduction and structural integrity are crucial for performance and safety.

While flexibility might be beneficial in certain applications, excessive flexibility in the skin could lead to buckling or deformation under stress. Weight is often minimized in monocoque designs to enhance performance, but it does not directly contribute to strength. Compression resistance is important but does not encompass the overall structural performance of the entire covering like structural rigidity does. Therefore, structural rigidity is the key property that ensures the strength of a monocoque design.