European Benchmark on Numerical Prediction of Stability and Control derivatives.

Abstract

Reliable prediction of flight dynamic criteria is conditioned by a satisfactory prediction of aerodynamic static and dynamic derivatives. A numerical benchmark has been conducted within the framework of the European Project SimSAC “Simulating Aircraft Stability And Control Characteristics for Use in Conceptual Design”. The objective was to establish the ability as well as the productivity of different tools to predict stability and control derivatives. Different levels of fidelity have been included, from quasi-steady VLM to fully unsteady RANS solvers. The numerical data have been compared to experimental ones, on the DLR-F12 generic civil aircraft. It has been wind-tunnel tested during the project, with several forced-motion oscillations; the data base includes unsteady pressures (not analysed in this paper). The study confirms that an increase in fidelity level allows for a better estimation of dynamic derivatives. VLM tools can give very satisfactory results but are very sensitive to the geometry/mesh input data. All the quasi-steady CFD approaches give very comparable results (robustness) on steady dynamic derivatives. However, they do not allow for the prediction of unsteady components of the dynamic derivatives (so called damping derivatives): this can be done with either a fully unsteady approach (with a time-marching scheme) or with Frequency Domain solvers, both of them giving very comparable results.