Parachute Dynamic Stability and the Effects of Apparent Inertia

The dynamic stability and equilibrium conditions of a parachute are studied using a six degree of freedom dynamic model that includes apparent inertia effects. Existing parachute dynamic models are discussed and the selection of a relevant model is shown. The chosen dynamic model that incorporates apparent inertia is summarized and used for analysis. The moments on the parachute system caused by the apparent inertia term are shown to affect both the equilibrium point and the stability of the system. The adjustment to equilibrium is observed and discussed. A small disturbance stability analysis is performed to give a stability criterion in terms of the slope of the tangential aerodynamic force. The dynamic modes, pitching and coning, are discussed. Computational integration of the equations of motion is used to validate the small disturbance analysis as well as to show the effects of large disturbances.