What distinguishes a monocoque structure from a semi-monocoque structure?

A monocoque structure is characterized by its reliance on the outer skin to bear loads, meaning it does not require additional internal frameworks for strength. This design allows for a lighter overall structure since the skin itself is integral to the structural integrity of the component. As a result, monocoque structures are often simpler and can be molded into complex shapes more easily.

In contrast, a semi-monocoque structure incorporates both an external skin and internal frames or ribs that provide additional support. This design feature offers a balance of strength and flexibility, enhancing the load-bearing capabilities without solely depending on the outer layer. While semi-monocoque structures can be strong, they add weight due to the internal components.

Understanding this distinction is essential in aeronautics and engineering, as it influences design choices depending on the specific structural needs and weight considerations of the aircraft or components involved.