A flight dynamics simulation capability with an add-on nonlinear aeroelastic solver using N-S solver generated ROMs is still not available within NASA. NASA has been working for many years towards achieving a software package that would accurately predict the interaction between flight dynamics considering structural flexibility in closed-loop with flight control laws. NASA is currently working on several N+3 advanced aircraft design concepts such as Truss-Braced Wing, Blended Wing-Body and Supersonic Business Jet. These advanced aircraft design concepts will be more flexible, more slender, and/or sizable where there may be insufficient frequency separation between the rigid body dynamics and the relatively low frequency elastic modes. The flight control law based on the rigid model may result in an unacceptable stability or an undesirable response characteristic due to control input or turbulence. The NL-DFS system will allow these advanced aircraft design concepts to be tested in a cost-effective manner; while increasing performance and confidence in the control law designs.
The maneuver and gust loads on transport aircraft usually are two of the critical design loads that dominate the structural design. To avoid the weight penalty by reducing the dynamic loads, modern commercial aircraft usually are equipped with a maneuver and gust load alleviation control system using the aileron and spoiler to provide the control authority. To suppress the body-freedom flutter and limit cycle oscillation problems, several military aircraft are equipped with a flutter suppression control system. To verify the performance of these control systems, it usually requires an enormous amount of wind-tunnel testing and flight testing to tune the control laws. The proposed NL-DFS system can be used as a virtual flight test environment in which control law testing can be performed; thereby reducing the number of wind tunnel and flight tests.