Aerodynamic Analyses and Database Development for Lift-Off/Transition and First Stage Ascent of the Ares I A106 Vehicle

Abstract

= 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

Overview of Ares-I CFD Ascent Aerodynamic Data Development And Analysis Based on USM3D

“…Examples of such trade studies included the height variations of the upper stage system tunnel and LH2 feed-line; and/or replacing of the upper stage pressure tunnel with the system tunnel, etc. Complementary to the experimental data, all the CFD results were also made available to the appropriate ascent aerodynamic database development team [7] as well as the uncertainty quantification group [8]. Although, the GN&C aerodynamic database was primarily developed from the wind tunnel data due to their consistency in acquiring large amount of data points in a timely manner, the available CFD results were used as a sanity check to anchor the measurements.…”

Assessment of CFD-based Response Surface Model for Ares I Supersonic Ascent Aerodynamics

“…The full description of the development of the final A106 AFMA DB is provided in Ref. 26, while the details of the uncertainty analysis are presented in Ref. 10.…”

“…26 An axisymmetric model (designated the C4 configuration) of the A106 OML with all protuberances removed was tested in UPWT Test 1972/1843, and the DB team used this data to remove systematic errors associated with the wind tunnel from the baseline A106 configuration (C1) data. Both the axisymmetric configuration and the baseline configuration were tested using pitch sweeps at fixed aerodynamic roll angles and roll sweeps at fixed total angles of attack.…”

Aerodynamic Characterization of a Modern Launch Vehicle

“…In addition, the auto pilot design did not provide positive control of sideslip and was not fully evaluated for off-nominal flight. Lessons learned from that flight failure included the need (1) to conduct a standard wind tunnel testing program which would have shown the errors in the originally predicted aerodynamics, (2) for an improved autopilot which would blend "skid and bank-to-turn" characteristics, (3) for a more accurate method for estimating sideslip, and (4) for improved filtering to prevent structural bending modes from corrupting vehicle rate and acceleration signals. A specific example of the shortcomings of the original dataset is shown in the graph in figure 3, which shows that for the standard length Pegasus vehicle, labeled Std in the figure, the level of roll stability, C l β , was approximately twice what was predicted.…”

“…These vehicles include the Ares I vehicle, which is intended to deliver a crewed capsule to Earth orbit, the Ares I-X, which was the first developmental flight test of the Ares I vehicle, and Ares V, which is a heavy lift vehicle intended to boost other equipment that can be used to deliver the crew and capsule to the Moon and back. Other papers in the sessions of this conference devoted to the Ares project summarize the Ares I-X flight test, 1 the Ares I database development, 2,3 details of the experimental ascent flight program, [4][5][6][7][8] experimental descent program, 9,10 computational studies for both the Ares I [11][12][13][14][15][16] and Ares V projects, [17][18][19] stage separation simulation, 3,5 modeling the effectiveness of the roll control system (RoCS), 13,15 lessons learned concerning uncertainty quantification, 20 aero-acoustic quantification, 21 impact of real-gas effects, 14 plume effects, 22 testing techniques for launch tower interference, 6 venting, 23 flexible vehicle stability, 24 debris transport, 25 and other aspects of the development project. [26][27][28] The current paper gives the general background of the Ares project and includes examples of previous launch programs that experienced pitfalls in characterizing their aerodynamics, summarizes the Ares Aerodynamics Panel, overviews testing and computational strategies, summarizes the workings of both the database team and the uncertainty teams, presents highlights of both the experimental and computational efforts, and lists lessons learned.…”