Free Vortex Wake methods
One step higher on the ladder in aerodynamic modeling from BEM are lifting line free vortex wake methods, which still make use of aerodynamic lookup tables. However due to the fact that the wake is modeled in a physical way, the phenomena which are related to the calculation of the so-called induction are treated much more reliable than done in many of the engineering models [Hauptmann et al, 2012]. The combination of the small time step requirement for load case calculations and the minimum discretization distance of the wake often still results in an unacceptable computational time. However a limited number of load cases for which the engineering methods are known to be inaccurate (e.g. yawed load cases) can then be modeled with the more advanced free wake method [Boorsma, 2011]. Developments to decrease the amount of necessary wake points through input of empirical relations together with a promising increase in computer power could lead to application of this model for load case calculations in the future.