Why are integral fuel tanks commonly used in large aircraft?

Integral fuel tanks are commonly used in large aircraft primarily because they help to reduce weight. These tanks are designed as an integral part of the aircraft's structure, typically formed within the structure of the wings or fuselage itself. By utilizing the available space in structural components, integral fuel tanks eliminate the need for additional, separate fuel tankage, which would add extra weight.

This design approach leads to a more efficient overall structure, as the strength of the aircraft's wings or fuselage is utilized to contain fuel while also contributing to the aircraft’s support. Therefore, the overall weight savings achieved with integral fuel tanks can also contribute to improved performance and efficiency during flight. Reducing weight is crucial for large aircraft, as it directly impacts fuel consumption, payload capacity, and aerodynamics, which are all vital aspects of aircraft design and operation.