Flight Simulation Within the Frame of Multidisciplinary Optimization of Large Flexible Aircraft

The disciplines flight mechanics I flight control and structural dynamics have to work closely together when large flexible aircraft, such as A340-600 and A3XX, are designed. The flight-control system has to be designed under the constraint that structural oscillation resonances or unacceptable levels of structural loads have to be avoided. Especially the integration of flight control and structural control requires multidisciplinary cooperation. In the potential conflict between handling qualities and minimal structural loads requirements the flight-control law parameters have to be optimized. This paper describes enhancements of real-time flight simulation in order to integrate the pilot into the control loop especially with respect to the effects of cockpit accelerations. The enhancements cover the coupling of rigid body motion and flexible modes in order to analyze the effects of neighboring frequencies, as well as the inclusion of simplified loads computation within the real-time simulation environment. Moreover, a cost-effective way of simulation-model development is presented. This covers model development and testing/validation on a fixed-base engineering flight simulator followed by a proven model transfer onto a six degrees of freedom motion simulator where intensive pilot-in-the-loop investigations can be carried out.