An investigation has been conducted in the NASA Langley Research Center 14-by 22-Foot Subsonic Wind Tunnel to obtain the liftoff and transition aerodynamics of the Ares I (A106) Crew Launch Vehicle. Data were obtained in free-air at angles of attack from -10° to 90° at various roll angles and at roll angles of 0° to 360° at various angles of attack. In addition, tower effects were assessed by testing with and without a mobile launcher/tower at all wind azimuth angles and at various model heights to simulate the rise of the vehicle as it clears the tower on launch. The free-air data will be used for low speed high angle of attack flight simulation and as a bridge to the low angle of attack ascent database (0.5 < Mach < 5.0) being developed with data from the Langley Unitary Plan Wind Tunnel and Boeing Polysonic Wind Tunnel. The Ares I Database Development Team will add incremental tower effects data to the free-air data to develop the database for tower clearance.

During the high-Mach-number, high-altitude portion of the first entry of the Shuttle Orbiter, the vehicle exhibited a nose-up pitching moment relative to preflight prediction of approximately ACre = 0.03. This trim anomaly has been postulated to be due to compressibility, viscous, and/or real-gas (lowered specific heat ratio "7) effects on basic body pitching moment, body-flap effectiveness, or both. In order to assess the relative contribution of each of these effects, an experimental study was undertaken to examine the effects of Mach number, Reynolds number, and ratio of specific heats. Complementary computational solutions were obtained for wind-tunnel and flight conditions. The primary cause of the anomaly was determined to be lower pressures on the aft windward surface of the Orbiter than deduced from hypersonic wind-tunnel tests with ideal-or near-ideal-gas test flow. The lower pressure levels are a result of the lowering of the flowfield "7due to high-temperature effects. This phenomenon was accurately simulated in a hypersonic wind tunnel using a heavy gas, which provided a lower "7,and was correctly predicted by Navier-Stokes computations using nonequilibrium chemistry.

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Notice to the Reader The Space Launch System, including its predicted performance and certain other features and characteristics, has been defined by the U.S. Government to be Sensitive But Unclassified (SBU). Information deemed to be SBU requires special protection and may not be disclosed to an international audience, such as the audience that might be present at the 2015 AIAA SciTech Conference. To comply with SBU restrictions, details such as absolute values have been removed from some plots and figures in this paper. It is the opinion of the authors that despite these alterations, there is no loss of meaningful technical content. Analytical methodologies and experimental capabilities are discussed; significant technical results are presented; and meaningful conclusions and lessons learned are provided.