Low speed aerodynamics and landing characteristics of sharp-class crew transfer vehicle concepts

A study is performed examining the low speed aerodynamic performance and landing characteristics of a preliminary new Crew Transfer Vehicle (CTV). The new vehicle employs a sharp nose with Ultra- High Temperature Ceramic (UHTC) thermal protection instead of the blunt nose of carbon-carbon material that is typically used. Designated the SHARP-V5, this new vehicle is compared against a well documented blunt-nosed CTV named HL-20, developed by NASA Langley Research Center in the early 1990s. The advantages of using a sharp nose to improve hypersonic performance, where significant benefits in cross-range and abort safety are gained, must be weighed against the aerodynamic changes that occur during low speed flight and landing. Critical aerodynamic parameters for landing performance such as L/D_max and CL_max are examined and compared for the two vehicles. Results are presented from both computational fluid dynamics analysis and wind tunnel testing of the SHARP-V5 as well as a technology demonstrator design, SHARP-LI. The configuration changes that were necessary to obtain adequate low speed aerodynamic performance from the sharpnosed vehicle are described and analyzed.