A process is developed to perform thermal and structural analysis and sizing and to perform sensitivity studies on the latest metallic thermal protection system developed at NASA Langley Research Center. The process defined can be used to determine appropriate materials and approximate thicknesses and is the basis for initial thermal protection system weight estimates. Metallic thermal protection systems are a key technology for reducing the cost of reusable launch vehicles, offering the combination of increased durability and competitive weights when compared to other systems. Accurate sizing of metallic thermal protection systems requires combined thermal and structural analysis. Initial sensitivity studies were conducted using transient one-dimensional finite element thermal analysis to determine the influence of various design and analysis parameters on thermal protection system weight. The thermal analysis model was then used in combination with static deflection and failure mode analysis of the thermal protection system sandwich panel outer surface to obtain minimum weight configurations at three vehicle stations on the windward centerline of a representative reusable launch vehicle. The coupled nature of the analysis requires an iterative analysis process, which is described. Findings from the sensitivity analysis are reported, along with preliminary designs at the three vehicle stations considered.Nomenclature d e = honeycomb cell size, ft d g = gas collision diameter, ft H g = gas enthalpy, Btu/lbm H rec = recovery enthalpy, Btu/lbm h = heat transfer coefficient, lbm/ft 2 · s K B = Boltzmann constant, Btu/R k g = gas thermal conductivity, Btu/ft-s-• R k * g = temperature-dependent gas thermal conductivity for air, Btu/ft-s-• R k rad = equivalent conductivity, radiation in honeycomb core, Btu/ft-s-• R L = diagonal length of thermal protection system (TPS) panel, ft L e = enclosure characteristic length, ft L h = honeycomb thickness, ft Pr = Prandtl number p atmospheric = atmospheric pressure at current altitude, lbf/ft 2 p e = pressure in enclosure, lbf/ft 2 p local static = local static-normal aerodynamic pressure, lbf/ft 2 q = integrated heat load, Btu/ft 2 q = heat flux, Btu/ft 2 · s T av = average temperature in rod element, • R T e = temperature in enclosure, • R T surf = TPS surface temperature, • R α = accommodation coefficient γ = specific heat ratio for air p aerodynamic = aerodynamic pressure differential, lbf/ft 2 p rms, acoustic = rms acoustic pressure differential, lbf/ft 2