| Momentum vector control for automatic recovery from nonlinear flight conditions of general aviation aircraft, such as spin, is studied. When an airplane enters a spin, it experiences large angular velocity and high angles of attack making it difficult to control. This loss of control can be considered as a serious source of aviation accidents. In this study, a systematic approach to momentum vector control is proposed. To arrest rotation and recover from the spin, the direction and magnitude of linear and angular momentum vectors, which are different direction and magnitude from their steady-state and/or pre-spin entry values, are controlled to restore the desired direction and magnitude. This means restoring the desired values of airspeed, angle of attack, sideslip angle, and angular velocity to their pre-spin values. To achieve this objective, a reasonably improved and reliable aerodynamic model is provided. The aerodynamic model is based on the multipoint approach to take into account the effect, caused by the rotation of the airplane. The model is improved by separating the effects of the controls. The control model is obtained by curve fitting using measured static wind tunnel data to find desired control derivatives as a function of angle of attack. In addition, required control surface deflections to recover from spin are computed by minimizing an objective function consisted of linear and angular momentum terms applied to the spinning airplane. Simulated time histories are similar to the histories that a test pilot managed to recover. Also, the proposed approach made possible the recovery from a case in which the trained pilot could not recover. These results indicate the validity and reliability of this proposed approach. |
