HANDLING QUALITIES OF LARGE FLEXIBLE AIRCRAFT

Scope and Method of Study. The effects on handling qualities of elastic models interaction with the rigid body dynamics of a large flexible aircraft are studied by a mathematical computer simulation. An analytical method to predict the pilot ratings when there is a severe modes interaction is developed. This is done by extending the optimal control model of the human pilot response to include the mode decomposition mechanism into the model. The handling qualities are determined for a longitudinal tracking task using a large flexible aircraft with parametric variations in the undamped natural frequencies of the two lowest frequency, symmetric elastic modes made to induce varying amounts of mode interaction.;Findings and Conclusions. The modified model of the human pilot response developed in this study proved successful in discriminating when the pilot can or cannot separate rigid from elastic response in the tracking task. A comparison of the model predictions with the past experimental data shows that the modified pilot model is much better in predicting the elastic modes interaction effect on the handling qualities than the standard optimal control model of the human pilot. The techniques developed here make it easier to investigate the effects of elastic modes interaction with the rigid body dynamics of a large flexible aircraft on the handling qualities in a preliminary design stage.