Radiative equilibrium surface temperatures and surface heating rates from a combined inviscid-boundary layer method are presented for the X-34 Reusable Launch V ehicle for several points along the hypersonic descent portion of its trajectory. I n viscid, perfect-gas solutions are generated with the Langley Aerothermodynamic Upwind Relaxation Algorithm LAURA and the Data-Parallel Lower-Upper Relaxation DPLUR code. Surface temperatures and heating rates are then computed using the Langley Approximate Three-Dimensional Convective Heating LATCH engineering code employing both laminar and turbulent ow models. The combined inviscid-boundary layer method provides accurate predictions of surface temperatures over most of the vehicle and requires much less computational e ort than a Navier-Stokes code. This enables the generation of a more thorough aerothermal database which is necessary to design the thermal protection system and specify the vehicle's ight limits. Research Engineer, Aerothermodynamics Branch, Aeroand Gas-Dynamics Division. Senior Member AIAA.

The hypersonic aerodynamic characteristics of a winged body concept representing a candidate singlestage-to-orbit vehicle which features wing tip fin controllers and elevon/bodyflap control surfa'Fs are predicted at points along a nominal trajectory for Mach numbers from 5 to 27 and angles of attack from 19 to 32 degrees. Predictions are derived from surface properties based on flow solvers for inviscid and viscous, laminar flows acting as a perfect gas, as a gas in chemical equilibrium and as a gas in chemical nonequilibrium. At a Mach number of 22, the lateral aerodynamic characteristics of the vehicle are determined based on an inviscid analysis at side slip angles of 2 and 4 degrees and 32 degrees angle of attack; a viscous analysis was carried out to determine the effect of gas chemistry model on surface pressure and to determine the incremental aerodynamics for control surface deflections. The results show that the longitudinal pitch characteristics of the baseline configuration, i.e., zero control surface deflections, are significantly altered by real gas chemistry at angles of attack greater than 30 degrees and Mach numbers greater than 9; and, that aerodynamics derived from inviscid solutions are of sufficient accuracy for preliminary analysis. Also, it is shown that a Mach number of 22, the choice of gas chemistry model has a largeimpact on surface pressure levels at highly localizedregions on the vehicle and that the vehicle can be trimmed at control surface deflections less than 11 degrees.