Development of a Flight Mechanics Simulation Computer based on a Flexible Aircraft Model for a Regional Aircraft

Abstract

Abstract The changes on aircraft structures and the increased use of advanced and light materials have led to the design of more efficient and flexible aircraft. This implies that rigid body dynamics is no longer sufficient to describe the aircraft behaviour in atmospheric flight. Coupling between structural and rigid body dynamics should be included, due to frequencies of structural modes. In this work, an analytical method, based on a mixed Newtonian-Lagrangian approach, is used to derive a simplified model of a flexible aircraft. Moreover, flexible displacements and torsional variables, starting from the Lagrange’s equations, are discretized by means of a finite number of generalized coordinates. This approach allows to derive directly a finite-order system of ordinary differential equations, making it less complex and suitable for real time simulation and control law synthesis. The main objective of the proposed methodology is the real-time implementation on a “flyable” hardware, for experimental tests, including sensor models. In detail, accelerometers on selected wing sections are design to measure the effect of flexibility in terms of bending and torsional deformations. A simplified low-order model is designed for a regional aircraft, including different masses and flight conditions. Moreover, only two symmetrical bending modes and one torsional mode are considered in the flexibility definition. Finally, the hinge moments acting on the control surfaces are evaluated. The hinge moment is calculated as the aerodynamic torque generated on the hinge axis by the variation of the pressure distribution acting on the control surfaces. A gust response of this aircraft is mainly analysed, considering both a discrete gust model and a continuous model. This research is performed within the ASTIB project, which has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation program under grant agreement CSJU – GAM REG 2014-2015.