In order to provide a method for evaluating flight control systems with the wind tunnel based virtual flight testing and provide a guide for building virtual flight testing systems, the virtual flight testing evaluation method was researched. The virtual flight testing evaluation method consisted of three parts: virtual flight testing method, virtual flight testing data processing method, and flight control system performance determination method, which were respectively designed for a pitching control system. Then, the hardware-in-the-loop simulation evaluation method was presented, and comparisons between the virtual flight testing and hardware-in-the-loop simulation evaluation method were conducted to highlight the characteristics of virtual flight testing evaluation method. Finally, virtual flight testing simulation models of a sample air vehicle were built and virtual flight testing were simulated to demonstrate the virtual flight testing evaluation method, which is helpful for the understanding of the virtual flight testing evaluation method with more sensibility. The evaluation results show that the virtual flight testing evaluation method designed can be used for flight control system evaluation.
I.INTRODUCTION As the traditional hardware-in-the-loop simulation (HILS) in the laboratory for flight control system (FCS) evaluation has to build the mathematical models for aircraft aerodynamics and attitude motions, it still has a great distance away from the totally real flight tests. To replace the mathematical aerodynamic models and attitude models in HILS with real factors, wind-tunnel hardware-in-the-loop simulation (WT-HILS) was used. In WT-HILS, the aerodynamic forces act on the aircraft model in real-time by putting the aircraft model under the simulated airflow in wind tunnel and the aircraft model perform the real attitude motions under the control of the real FCS as shown in FIG. I. Obviously, the WT-HILS is more realistic than the traditional laboratory based HILS. If the WT-HILS is applied to evaluate the FCS before flight tests and after HILS, some FCS errors, such as the control loss in unsteady motions that may occur in real flights and are not detected in HILS can be exposed by WT-HILS. Therefore, the risks of flight tests can be farther reduced by WT-HILS.
In this paper, the differential quadrature method (DQM) was extended to deal with the nonlinear thermal flutter problem of supersonic composite laminated panel. Based on Hamilton's principle, the nonlinear thermal flutter model of composite panels was first established. The model adopted the von Karman large deflection plate theory for the geometrical nonlinearity, and the third order piston theory for the supersonic aerodynamic loads. Convergence and accuracy studies were carried out to verify the proposed approach. Finally, the nonlinear thermal flutter characteristics of a supersonic composite panel were studied. Uniform temperatures were first applied to the model in order to determine general heating effects on the stability of the composite panel. Owing to the varying structural stiffness of composite panels when subjected to thermal stresses, the thermal load reduced the frequency of composite panel, as well as the frequency interval between the first frequency and the second frequency; thereby hastening the flutter of composite panel. The nonlinear thermal flutter velocity ratio was decreased with respect to increasing temperature load for all aspect ratios. However, the influence of thermal loadings on flutter with various cross angles was different. Cases of unequal temperatures were considered. The average temperature load was kept constant which differs from the temperature gradient form of loading. The results show that the nonlinear thermal frequencies are affected in the presence of different temperature distributions. The changes in the temperature distribution have a slightly greater effect than changes in the average temperature. These effects due to temperature distribution changes do not have a substantial effect on the flutter dynamic pressure.
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