Achieving a Realistic Model of Flight Dynamics and Aeroelasticity of Flexible Aircraft

Researchers at NASA’s Armstrong Flight Research Center have developed a method that allows for the translation of frequency-domain aerodynamics from commercial code (e.g., ZAERO™ or NASTRAN®) to a time-domain formulation that can be easily understood by flight control engineers, and eliminates the complications inherent in previous methods. These previous methods were designed for structural control (independent of flight dynamics) and are therefore formulated in the inertial (stationary) modal reference frame, which cannot accurately capture phugoid mode dynamics without significant complexity. Thus, a non-inertial reference frame was required to correctly model flight dynamics — a goal previously achieved by applying a transformation to the final statespace model. However, the transformation method created numerical errors, leading to problems in model simulation, reduction of the order-for-control development, and decreased accuracy.