Nonlinear Flight Dynamics Simulation Model for a Civil Aircraft with Active High Lift System

Abstract

The design of innovative control concepts by using the opportunities of an active high lift system is only possible with a proper understanding of the underlying flight dynamics of active high lift aircraft. This report shows the achievements in flight dynamics simulation model design. The target of this work is to create a nonlinear mathematical model, which describes the dynamic behavior of an active high lift aircraft and which provides direct access to the active high lift system in order to use it for aircraft control. The main focus lies on the development of a suitable model structure and the design of an aerodynamic derivative model. In addition an engine model which allows for usage of bleed air for blown flaps has to be established and integrated into the simulation environment. The consistent further development of an existing model structure for conventional aircraft, as well as the identification of the aerodynamic model by analysis of SFB 880 created CFD results will be presented. The modeled effects of the active high lift system on aerodynamics are introduced and the existing nonlinearities which are occurring due to stall are explained. These nonlinearities are also reflected in the model for downwash and pitching moment. The resulting characteristics of the aerodynamic model and their impact on the longitudinal motion of the aircraft will be demonstrated and discussed.