| This thesis compares the results of two of the more popular flexible aircraft modeling formulations, the mean-axes method and the fixed-axes method, for application in real-time motion simulators. First, the time-domain equations of motion for an elastic body using the fixed-axes are derived. Subsequently, the mean-axes equations are derived by making a few assumptions from the fixed-axis equations. The two formulations are then implemented for a scaled-up beam model of a Cessna Citation aircraft, with the deformations represented by the modal expansion of the whole aircraft from their respective constrained and free-free finite element solutions. Time-domain results, consisting of the acceleration, velocity, and attitude of a point on the aircraft body, are obtained in both models at two beam-stiffness configurations using a quasi-steady aerodynamic model for a single maneuver at one flight condition. The two methods produced similar results with the fixed-axes formulation producing slightly more accurate results. |
