The overall technical objective of the Phase I effort is to develop a nonlinear aeroelastic solver utilizing the FUN3D generated nonlinear aerodynamic Reduced Order Model (ROM). Two types of aerodynamic reduced order models will be developed; the first is the Neural Network nonlinear ROM that can provide the aerodynamic feedback forces due to structural deformation and the second is a nonlinear Volterra-kernels-based gust ROM that provides the aerodynamic forces due to gust excitation. Once developed, this nonlinear aeroelastic solver will be integrated into the Nonlinear Dynamic Flight Simulation (NL-DFS) system in Phase II to perform flight dynamic simulation including nonlinear aeroelastic and nonlinear rigid body interaction effects, which can be used to predict the gust loads, ride quality, flight dynamic stability, and aero-structural control issues. In addition, the nonlinear aeroelastic solver developed can be a standalone code for rapid static/dynamic aeroelastic analysis. With the utilization of the FUN3D generated nonlinear aerodynamic (ROM), this nonlinear aeroelastic solver will be computational efficient for accurate flutter analysis, gust loads analysis and limit cycle oscillation analysis.