Novel Fragment Aerodynamic Models over Entire Velocity and Altitude Range

A novel methodology has been developed to predict both the steady and unsteady aerodynamic characteristics of complex fragment shapes resulting from the impact of Missile Defense Agency (MDA) interceptors with target vehicles. The particularly innovative unsteady force coefficient model provides for the calculation of fluttering, tumbling, and chaotic tumbling of fragments utilizing a rotational lift term in the aerodynamics model. This capability satisfies an important requirement of dispersion analysis: to understand the tumbling behavior that most fragments undergo. The steady flow model combines free molecular flow modeling with continuum models using flight-data derived bridging functions. The tumbling and steady descent models are being organized into a software package that will be seamlessly implemented into the Kinetic Impact Debris Distribution (KIDD) code. Model validation will be acquired using fragment drop tests and actual flight-test data.