Modeling and Simulation of Parachute Apparent Mass Aerodynamics for the Dragonfly Mission

Analytical expressions to model the apparent mass aerodynamic forces and moments for the Dragonfly drogue and main parachutes are presented. Model parameters are determined from a reconstruction of the dynamic motions of a subscale parachute in a wind tunnel. The apparent mass model formulation and model parameters are implemented in a multibody simulation and is validated against the entry vehicle dynamics (attitude and rotation rates) measured during subscale drop tests of the Dragonfly drogue and main parachute configurations. The apparent mass aerodynamics model is applied to the end-to-end entry, descent, and landing simulation of the Dragonfly mission. The simulated entry vehicle/lander dynamics during main parachute descent using the apparent mass aerodynamics (tensor) model are more conservative than those using the heritage (point mass) apparent mass model. The simulated entry vehicle dynamics during drogue parachute descent are insensitive to the to the apparent mass model.