Numerical computations of flowfields and laminar heating rates around the Space Shuttle Orbiter windward surface, including the root of the wing leading edge, are presented to illustrate the sensitivity of these calculations to several flowfield modeling assumptions. Specifically, results obtained using the axisymmetric analogue concept to predict "three-dimensional" heating rates, in conjunction with exact three-dimensional inviscid flowfield solutions and two-dimensional boundary-layer analysis, show the sensitivity of boundary-layer edge conditions and heating rates to considerations of: 1) the inviscid flowfield "entropy layer," 2) equilibrium air vs chemically and vibrationally frozen flow, and 3) nonsimilar terms in ttie boundary-layer computations. In addition, a cursory comparison between flowfield predictions (made at critical points in the current design trajectory) obtained from these methods and current Orbiter design methods has established a benchmark for selecting and adjusting these and future design methodologies.

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