Study of jettison dynamic force and "zero-zero" jettison

Based on a detailed analysis of "zero-zero" jettison, the study presents several numerical models for simulating the charging process of an actuating system and motions of the actuating cylinder and canopy. Through solving the above models, the pressure changes in the upper and lower chambers of the actuating cylinder are accurately predicted, which makes up for the shortage of data from dynamic force experiments in previous studies. To study whether or not it is necessary to consider aerodynamic forces in the prediction of "zero-zero" jettison, non-dimensional transformations of canopy trajectories in "zero-zero" jettison tests are performed. It is found that the impact of aerodynamic forces can be neglected in the prediction of the free-jettison step of the "zero-zero" jettison process. Furthermore, canopy trajectories at the axis-rotated step of the "zero-zero" jettison are predicted with and without considering aerodynamic forces. Comparisons of the test results indicate that prediction results which take aerodynamic forces into consideration are closer to experimental results.