The aim of this Chapter is to present recent advances in the development of high-fidelity simulation software for virtual flight testing of unconventional and next-generation aircraft. The accurate and efficient simulation of the full set of physics associated with aircraft flight operations including flight control, aerodynamics, and structural dynamics is discussed. Pivotal to this framework is a novel adaptive design of experiment algorithm for the rapid generation of the aerodynamic database that is developed and demostrated on a complete aircraft with highly nonlinear aerodynamics. Throughout the Chapter, several worked-out examples and problems are introduced to aid the reader to gain competence and proficiency in the methods and computer codes accompanying this Chapter. The Chapter continues with Section 1.1 overviewing the state-of-the-art in virtual flight simulation. It continues in Section 1.2 with a discussion of the aerodynamic model traditionally used for flight simulation. Then, surrogate modelling and adaptive design of experiment are developed in Section 1.3. Finally, advanced models used for virtual flight simulation are presented in Section 1.4.