Study of deep-stall characteristics and longitudinal special phenomena of T-tail aircraft

Deep-stall seriously threatens the safety of aircrafts; a detailed research has been carried out to make a full study on the influencing factors in avoidance of flight accidents in this paper. The Bifurcation analysis and catastrophe theory method (BACTM) is employed to analyze the deep-stall characteristics of four different configuration T-tail aircrafts with various pitching-moment curves, and some potential nonlinear motion phenomena are given using the phase plane α - q and time histories of the angle of attack. In addition, taking into account the actual flight conditions, effect of atmospheric turbulence is also investigated. The results indicate that the reversal slope of pitching-moment curves may cause the deep-tall condition. Other influencing factors include the depth, the width, the location of the reversal slope, as well as the control-effectiveness of the elevator. Moreover, atmospheric turbulence speeds up aircrafts entering the deep stall condition. The research results have some reference values for the stall recovery.