Aerodynamic Characterization of New Parachute Configurations for Low-Density Deceleration

The Low Density Supersonic Decelerator project performed a wind tunnel experiment on the structural design and geometric porosity of various sub-scale parachutes in order to inform the design of the 110 ft nominal diameter flight test canopy. Thirteen different parachute configurations, including disk-gap-band, ringsail, disksail, and starsail canopies, were tested at the National Full-scale Aerodynamics Complex 80by 120-foot Wind Tunnel at NASA Ames Research Center. Canopy drag load, dynamic pressure, and canopy position data were recorded in order to quantify the relative drag performance and stability of the various canopies. Desirable designs would yield increased drag above the disk-gap-band with similar, or improved, stability characteristics. Ringsail parachutes were tested at geometric porosities ranging from 10% to 22% with most of the porosity taken from the shoulder region near the canopy skirt. The disksail canopy replaced the ringslot portion of the ringsail canopy with a flat circular disk and was tested at geometric porosities ranging from 9% to 19%. The starsail canopy replaced several ringsail gores with solid gores and was tested at 13% geometric porosity. Two disksail configurations exhibited desirable properties such as an increase of 6-14% in the tangential force coefficient above the DGB with essentially equivalent stability. However, these data are presented with caveats including the inherent differences between wind tunnel and flight behavior and qualitative uncertainty in the aerodynamic coefficients.