Although the quasi-steady aerodynamic modelling method remains in widespread use, its shortcomings in representing the stall and post-stall dynamics have been noted in the literature. Various methods to model the unsteady aerodynamics effects have been proposed as a result, although the direct implications on the aircraft’s flight dynamics characteristics have not been widely studied. In this paper, we combine the state-space method for unsteady aerodynamic modelling with bifurcation analysis to examine the sensitivity of stall and post-stall behaviour to the choice of unsteady modelling method: quasi-steady or unsteady. It is found that quasi-steady modelling is adequate for the chosen example of a T-tailed transport model. The study is then further expanded to investigate a hypothetical situation with highly unsteady aerodynamic characteristics, in which a significant degradation in flying qualities is observed using bifurcation analysis. These results highlight the need to implement unsteady aerodynamic modelling techniques in high-performance applications in order to sufficiently capture their dynamics. To help achieve this goal, bifurcation analysis can be a valuable companion to analyse the aircraft’s flying qualities in the presence of these unsteady effects.
|Journal||Journal of Aircraft|
|Publication status||Submitted - 22 Jul 2021|