This book deals with an exciting aeroelastic concept for an adaptive spring-mounted wing subjected to a freestream airflow. This so-called fluid-structure interaction is of particular interest in applications such as motor sports, aerospace or renewable energy sectors. Fluid–structure interactions can, on the one hand, lead to undesirable aerodynamic behaviour or, in extreme cases, to structural failure. On the other hand, improved aerodynamic performance can be achieved if a controlled application within certain limitations is provided. One application is the reduction of drag of road vehicles at higher speeds on a straight, while maintaining downforce at lower speeds during cornering.