Abstract: The present invention provides a structural element, in particular for an aircraft and spacecraft, comprising a core, the rigidity of which varies at least in portions for optimising the aeroelastic characteristics of the structural element The present invention also provides a method for producing a structural element, in particular for an aircraft and spacecraft, which comprises the following steps: provision of a structural element comprising a core; determination of the aeroelastic behavior of the structural element; and variation, at least in portions, of the rigidity of the core of the structural element such that the aeroelastic behavior of the structural element is optimised. The present invention further provides an aircraft and spacecraft comprising a structural element of this type, and a rotor blade, in particular for a wind turbine, comprising a structural element of this type.