Stability and Control of Tailless Aircraft Using Variable-Fidelity Aerodynamic Analysis

Abstract

The purpose of this study is to evaluate the stability and control characteristics of the tailless aircraft using a hierarchy of variable-fidelity aerodynamics analysis methods, including unsteady linear potential flow, Euler, and Reynolds-averaged Navier–Stokes solvers as low-, medium-, and high-fidelity analysis, respectively. Contributions of the study are numerous. First, derivations of the equations of motion for the tailless aircraft and stability criteria using system matrices in longitudinal and lateral motions were carried out. Second, an efficient time-spectral Reynolds-averaged Navier–Stokes computational fluid dynamics method, which is based on the solution approximation of a discrete Fourier series, and the steady form of a corresponding adjoint solution approach can compute dynamic derivatives at computational cost considerably less than that of the conventional time-marching method without deterioration in solution accuracy. The innovative control effector 101 configuration was chosen, and the validation of the variable-fidelity computation results was made with wind tunnel data for forces, moments, and their derivative values in static and dynamic motions. Finally, example flight conditions of trim, climb, and side slip motions were analyzed by the Reynolds-averaged Navier–Stokes solver for the stability analysis. It is concluded that the weak instabilities observed in some of the dynamic modes can be easily controlled by appropriate control inputs.