In preliminary aircraft design, aircraft manufacturers currently use semi-empirical evaluation methods, e.g. One key design discipline which is significantly impacted by structural design choices and active load control is flight mechanics, for which one must conduct assessments regarding safety and performance continuously. For an efficient process, it is essential to use accurate multi-domain tools and methods as early as possible to minimize development risks and avoid costly and time-consuming redesign loops. Within the design process, there are strong interdependencies between each involved discipline due to its interdisciplinary nature. Aircraft manufacturers strive to reduce structural loads by active load control which results in an additional reduction of the structural stiffness. New fuel-efficient aircraft designs have high aspect ratio wings and lower structural masses, as currently shown with A330-800 and B777x, and are more flexible.

This paper describes the combined toolchain and its application on a generic long-range reference aircraft to investigate the effects of load alleviation functions on passenger ride comfort and discusses the results. By conducting this assessment for a particular aircraft configuration, more insight into passenger ride comfort and the key contributors can be gained during preliminary design. This is particularly interesting since the implemented load alleviation functions are designed to reduce loads, and not explicitly to improve passenger ride comfort. To address this issue, the DLR MONA based design and the TUB flight mechanical assessment tool MITRA are linked to investigate the impact of the structural design on specific flight mechanical assessments such as passenger ride comfort. Current available tools and methods are not accurate enough for this task. For an efficient design process, it is essential to answer such questions with accurate multi-disciplinary tools and methods as early as possible to minimize development risk and avoid costly and time-consuming redesign loops. For example, it is important to know how at that design stage such flexible aircraft with load alleviation affect passenger ride comfort in turbulent flight. At the same time, the structural design impacts other disciplines in preliminary aircraft design, especially flight mechanics. Additionally, load alleviation functions are implemented to reduce the structural loads, which results in further reductions of the structural stiffness. Consequently, those aircraft are more flexible. New fuel-efficient aircraft designs have high aspect ratio wings.

Structural loads on aircraft