Aeroservoelastic Wing Sizing Using a Physics-Based Approach in Conceptual Aircraft Design

Abstract

State of the art wing sizing in conceptual aircraft design is usually carried out by semiempirical methods, or with static load cases and a rigid airframe structure. On the other hand, combining the disciplines aerodynamics, structures and flight dynamics catches the impact of dynamic aircraft behavior on the mass of the flexible wing. By taking coupled physics effects into account at the early design stage, technologies like gust and maneuver load alleviation can be assessed. Overall aircraft efficiency benefits are expected. This paper presents a process for the integration of flight control and aeroelasticity into conceptual aircraft design. The main goal is an expansion of the wing design by introducing mission based dynamic load cases performed with a flexible structure. The process uses the tool ASWING§ to perform an unsteady lifting line calculation combined with non-linear Euler beam theory. Structural wing sizing is performed on a long range transport aircraft design. Elements of an open source simulation library are used to perform a controlled six-degree-of-freedom flight simulation. The sizing process is calibrated with the properties of a higher fidelity structure model, based on steady load cases. A dynamic validation of the lower fidelity behavior is provided by a higher fidelity approach, using unsteady Reynolds-Averaged Navier-Stokes equations coupled with a structural modal ansatz in a free flight simulation. It is shown, that the conceptual sizing process captures the maximum loads and dominant dynamic effects. Therefore it is qualified for usage in conceptual aircraft design. Deviations are traced back to configuration differences between the models and fundamental differences of the modeling approach. The presented process enables the assessment of how specific flight control laws and layouts change the optimum aircraft design.