Experimental Investigation of Drag Modulation Aerocapture: Drag-Skirt Separation in Hypersonic Free Flight

Free flight tests were conducted in carbon dioxide at Mach 12 of notional drag modulation aerocapture configurations for a small satellite mission to Venus. The configurations were based on research conducted at the Georgia Institute of Technology, University of Colorado Boulder, Jet Propulsion Laboratory, and Ames Research Center. The drag modulation aerocapture approach being studied involves an atmospheric entry vehicle that employs an attached drag device, a drag skirt, that is jettisoned at the appropriate time to allow the payload-portion of the vehicle to exit the atmosphere, slowed enough to be captured into orbit. A total of eight tests were performed. Reynolds numbers, based on the pre-separation base diameter, ranged from 0.82 x 106 to 2.96 x 106. The tests demonstrated the feasibility of a clean drag skirt separation at hypersonic speeds and, for the conditions of the tests, the stability of the central flight system body during and after separation from the drag skirt. Two drag skirt geometries were tested: an axisymmetric conical frustum, and a faceted frustum representative of a mechanically-deployable device. Drag skirts of various masses were tested to examine the effect of pre- and post-separation ballistic coefficient ratio on the separation dynamics. A new test capability for multi-body interactions in hypersonic free flight was developed for these tests, and is described.