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Applications of Ultra-Low Ballistic Coefficient Entry Vehicles to Existing and Future Space Missions

Summary: Applications of Ultra-Low Ballistic Coefficient Entry
Vehicles to Existing and Future Space Missions
David L. Akin
Space Systems Laboratory, University of Maryland, College Park, MD 20742
The ballistic coefficient ( = m
) of entry vehicles has traditionally not been a design
parameter: the mass was fixed by the launch vehicle payload, the drag coefficient was de-
termined by the aerodynamic configuration, and the reference area (typically cross-section
area) was fixed by the launch vehicle diameter. If the ballistic coefficient is instead con-
sidered as a potential design parameter, several benefits result from driving to lower and
lower values. As the ballistic coefficient decreases, the peak stagnation point heating rate
and temperature decrease. As reaches the range of 150-300 Pa, the heat shield can be
deployed using a mechanical framework (much like an umbrella) supporting existing ce-
ramic fabric as the heat shield. Offsetting the center of gravity from the vehicle centerline
allows lift/drag ratios in the range of 0.15-0.25, which mitigates entry decelerations and
provides active targeting capability for a designated landing site. Due to the lower entry
temperatures, ionization of the surrounding air stream is reduced or eliminated, allowing
communications and GPS-based navigation throughout the entry trajectory. As the space-
craft enters the dense lower atmosphere, the low areal loading results in terminal velocities


Source: Akin, David - Department of Aerospace Engineering, University of Maryland at College Park


Collections: Engineering