Departure susceptibility and uncoordinated roll-reversal boundaries for fighter configurations

Abstract

A fighter's response to a severe application of controls is predicted as a function of its static lateral and directional stability derivatives and lateral control characteristics. This was accomplished by developing two boundaries which identify the onset of roll reversal and departure in terms of the lateral-directional characteristics. These boundaries demark four airplane response regions, i.e., commanded maneuver, commanded maneuver accompanied by an alpha excursion, uncoordinated roll reversal, and departure susceptibility. The responses within the latter two regions become progressively more severe the further the lateral-directional characteristics are displaced from the onset boundary values. The boundaries were developed and their sensitivity to other variables was determined through large-angle, six-degree-of-freedom parametric computer studies. Since they were found to be applicable for most fighter mass distributions and for a large range of pitch characteristics, it was concluded that they could be used for specification, design, and evaluation purposes.