= dispersed trajectories generated in GNC cycle 6 TD7 = dispersed trajectories generated in GNC cycle 7 TR5 = reference trajectory generated in GNC cycle 5 TR6 = reference trajectory generated in GNC cycle 6 TR7 = reference trajectory generated in GNC cycle 7 UPWT = Unitary Plan Wind Tunnel USM = ullage settling motor

A detailed uncertainty analysis for the Ares I ascent aero 6-DOF wind tunnel database is described. While the database itself is determined using only the test results for the latest configuration, the data used for the uncertainty analysis comes from four tests on two different configurations at the Boeing Polysonic Wind Tunnel in St. Louis and the Unitary Plan Wind Tunnel at NASA Langley Research Center. Four major error sources are considered: (1) systematic errors from the balance calibration curve fits and model + balance installation, (2) run-to-run repeatability, (3) boundary-layer transition fixing, and (4) tunnel-to-tunnel reproducibility. Nomenclature A101Ares This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.https://ntrs.nasa.gov/search.jsp?R=20080024105 2018-05-11T10:44:17+00:00Z Their primary differences are in the launch abort system, the blast shield covering the Orion Command Module, and the various protuberances. The identifiers for those configurations that are used in this paper are A101 for an earlier configuration and A103 for the current configuration. The designs are sufficiently different that the aerodynamics changes must be accounted for in the database. An artist's sketch of the current configuration at launch is shown in Figure 1. Note that there are three first-order loading regions for longitudinal aerodynamics: (1) crew capsule/service module, (2) interstage, and (3) aft skirt. Each protuberance creates a loading region which is secondorder for longitudinal aerodynamics, but which is first-order for lateral-directional aerodynamics.Each configuration was tested at the Boeing Polysonic blow-down wind tunnel (PSWT) for the Mach range, . The PSWT testing was conducted in the transonic test section which is four-foot square and has porous walls. Each configuration was also tested at the NASA Langley Research Center Unitary Plan Wind Tunnel (UPWT) for the Mach range, 1.6. The UPWT tests were conducted in two test sections: test section 1 for and test section 2 for 2.5 0.5The UPWT is continuous flow and both test sections have solid walls four-foot square. The PSWT tests used the NTF-107 force balance while the UPWT tests used the UT-39B balance. The full-scale calibration ranges (same as the maximum loading ranges) for the balances are given in Table 1. Also, given in Table 1 are the standard errors derived from the calibration curve-fit residuals. For all four tests, the force balances were attached to a straight sting which was attached to a roll motor and then to the tunnel mounting system. Base and cavity pressures were measured to correct them to free stream . Both pitch runs at constant zero roll angle and roll runs at constant pitch angles were obtained. The PSWT tests used continuous pitch and roll with data acquisition (digitization) at 100 frames a second that was post-processed with a digital filter at 20 Hz. The UPWT tests used pitch-pause and roll-pause data acquisition, acquiring data at 30 frames per se...

A number of varied test techniques have been utilized during Ares I aerodynamic characterization experimental investigations. Most of the aerodynamic wind tunnel testing utilized internal strain gauge balances to measure integrated forces and moments. Major concerns to the Performance and Guidance and Control disciplines were the axial force and aerodynamic induced rolling moment components of the vehicle. Specifically protuberance effects on rolling moment and roll control authority are a concern during lift-off and ascent.Another test technique that has been utilized in the Ares I vehicle development has been the use of surface pressures to measure distributed loads on the vehicle. One percent scale models have been tested in typical 4-foot subsonic/transonic and supersonic facilities. The slenderness of the vehicle has been a challenge in both the integrated force/moment testing as well as in the distributed loads testing. Distributed pressure loads are used by the Structures and Loads disciplines to assist in the design of the external panels and internal structure of the vehicle.In addition to the ascent aerodynamic experimental testing, some other specialized aerodynamic wind tunnel tests have been conducted. An investigation was conducted to evaluate ground wind loads, launch tower effects, and transition aerodynamics from lift-off to ascent flight. This test provided a database of proximity aerodynamics in the presence of the launch that reduced the risk of vehicle contact to the launch tower. Another specialized stage separation aerodynamic wind tunnel test was conducted in the AEDC Von Karman Facility Tunnel A specifically addressing proximity aerodynamics of the upper stage relative to the first stage. This test provided a more refined stage separation proximity aerodynamic database to eliminate some risk to the program regarding recontact between the two stages during ascent. This paper will provide an overview of the experimental aerodynamic characterization of the Ares I vehicle and detail the impacts the experimental program had on the development of the vehicle. It will also discuss the facilities and rationale for choosing specific facilities. In addition, the different experimental test techniques employed in the experimental program will be described.

Throughout three full design analysis cycles, the Ares I project within the Constellation program has consistently relied on the Boeing Polysonic Wind Tunnel (PSWT) for aerodynamic testing of the subsonic, transonic and supersonic portions of the atmospheric flight envelope (Mach=0.5 to 4.5). Each design cycle required the development of aerodynamic databases for the 6 degree-of-freedom (DOF) forces and moments, as well as distributed line-loads databases covering the full range of Mach number, total angle-of-attack, and aerodynamic roll angle. The high fidelity data collected in this facility has been consistent with the data collected in NASA Langley's Unitary Plan Wind Tunnel (UPWT) at the overlapping condition of Mach=1.6. Much insight into the aerodynamic behavior of the launch vehicle during all phases of flight was gained through wind tunnel testing. Important knowledge pertaining to slender launch vehicle aerodynamics in particular was accumulated. In conducting these wind tunnel tests and developing experimental aerodynamic databases, some challenges were encountered and are reported as lessons learned in this paper for the benefit of future crew launch vehicle aerodynamic developments. Nomenclature Symbols

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