Post ight analysis of the Mars Path nder hypersonic, continuum aerodynamic data base is presented. Measured data include accelerations along the body axis and axis normal directions. Comparisons of pre ight simulation and measurements show good agreement. The prediction of two static instabilities associated with movement o f the sonic line from the shoulder to the nose and back was con rmed by measured normal accelerations. Reconstruction of atmospheric density during entry has an uncertainty directly proportional to the uncertainty in the predicted axial coe cient. The sensitivity of the moment coe cient to freestream density, kinetic models and center-of-gravity location are examined to provide additional consistency checks of the simulation with ight data. The atmospheric density as derived from axial coe cient and measured axial accelerations falls within the range required for sonic line shift and static stability transition as independently determined from normal accelerations.

A study of the leeside ow c haracteristics of the Shuttle Orbiter is presented for a reentry ight condition. The ow is computed using a point-implicit, nite-volume scheme known as the Langley Aerothermodynamic U p wind Relaxation Algorithm LAURA.LAURA is a second-order accurate, laminar NavierStokes solver, incorporating nite-rate chemistry with a radiative equilibrium wall temperature distribution and nite-rate wall catalysis. The resulting computational solution is analyzed in terms of salient o w features and the surface quantities are compared with ight data. NomenclatureAcronyms AFRSI Advanced exible reusable surface insulation DFI Developmental ight instrumentation LAURA Langley aerothermodynamic upwind relaxation algorithm OMS Orbital maneuvering system PNS Parabolized Navier-Stokes RCC Reinforced carbon-carbon RCG Reaction cured gas RCS Reaction control system SILTS Shuttle infrared leeside temperature sensing STEIN Supersonic hypersonic three-dimensional external inviscid ow STS Space transportation system

As a preliminary step toward predicting the leeside thermal environment for winged reentry vehicles at ight conditions, a computational solution for the ow about the Shuttle Orbiter at wind tunnel conditions was made using a point-implicit, nite volume scheme known as the Langley Aerothermodynamic Upwind Relaxation Algorithm LAURA. The Scheme is a second-order accurate, upwind-biased Navier-Stokes solver capable of solving non-equilibrium chemistry ows with radiative equilibrium wall temperatures and nite-rate wall catalysis. For this study, h o w ever, the code is run in its simplest form, i.e., i n viscid ow using perfect gas chemistry. The surface pressures resulting from the computational solution are compared with wind tunnel data. The results indicate that the dominant i n viscid ow features are being accurately predicted on the leeside of the Shuttle Orbiter at a moderately high angle of attack.

Floweld solutions over the Mars Pathnder Probe spanning the trajectory through the Martian atmosphere at angles of attack from 0 to 11 degrees are obtained. Aerodynamic coecients derived from these solutions reveal two regions where the derivative of pitching moment with respect to angle of attack is positive at small angles of attack. The behavior is associated with the transition of the sonic line location between the blunted nose and the windside shoulder of the 70 degree half-angle cone in a gas with a low eective ratio of specic heats. The transition rst occurs as the shock layer gas chemistry evolves from highly nonequilibrium to near equilibrium, above approximately 6.5 km/s and 40 km altitude, causing the eective specic heat ratio to decrease. The transition next occurs in an equilibrium ow regime as velocities decrease through 3.5 km/s and the specic heat ratio increases again with decreasing enthalpy. The eects of the expansion over the shoulder into the wake are more strongly felt on the fustrum when the sonic line sits on the shoulder. The transition also produces a counter-intuitive trend in which windside heating levels decrease with increasing angle of attack resulting from an increase in the effective radius of curvature. Six-degree-of-freedom trajectory analyses utilizing the computed aerodynamic coecients predict a moderate, 3 to 4 degree increase in total angle of attack as the probe, spinning at approximately 2 revolutions per minute, passes through these regions.