Asymmetric Stall Modeling of the Cessna Citation II Aircraft

As of 2019, the FAA and EASA require all airline pilots to complete stall and recovery training as integral part of their training. To mitigate risks, this training takes place in ground-based simulators. To enable this, realistic models of aircraft behaviour in the stall regime need to be developed. In this paper, a newaerodynamic stall modelling methodology is proposed that combines classical aerodynamic model identification techniques with a novel adaptation of Kirchhoffs theory of flow separation that considers flow separation over both wings separately. This new model is called the 2X model, as it contains 2 independent flow separation variables, i.e. one for each wing. The model parameters are estimated based on flight experiments in the stall regime conducted with a Cessna Citation II laboratory aircraft operated by the TU-Delft. The developed model for the first time allows accurate prediction of lateral-directional dynamics encountered during stall such as e.g. wing-dip. In addition, it was found that the 2X model also improved predictions of longitudinal stall dynamics leading to a new extended envelope aerodynamic model for the Cessna Citation II that now also includes stall entry and post-stall aerodynamics.