Asymmetric Stall and Control Effectiveness reduction Modeling for the Cessna Citation II

Abstract

Since 2019, the FAA and the EASA impose to all airline pilots to follow, as part of their training, a stall and recovery training. To mitigate the risks, this training takes place in ground-based simulators. To make it happen, models of the aircraft behaviour at high angle of attack need to be developed. Among the different modeling approaches possible, when available in such flight conditions (i.e. at high angles of attack, near and beyond stall), the use of actual flight test data is particularly interesting as it makes this work not being just a simulation study. Additionally, the method already proved to be efficient and effective for aerodynamic modeling purpose, especially in the nominal flight envelope, but it has also demonstrated interesting and encouraging results in modeling an extended (longitudinal) flight envelope, including stall entry up to post-stall conditions, using Kirchhoff theory of flow separation. With this work, it is
intended to support the idea that despite the development of digital techniques (CFD, physical simulation, etc.) flight data based models are still tools of major importance in order to create and develop models capable of positive transfer of training for the pilots in simulators. The purpose of this research is to try to fill a gap in the modeling of the lateral-directional dynamics of stalls using flight test data, by making use of an extended and adapted version of Kirchhoff Theory’s of flow separation. From a numerical point of view, it then seems that this approach
allows to improve by a few % the accuracy of the lateral-directional model.