Experimental Hypersonic Aerodynamic Characteristics of the Mars Surveyor 2001 Precision Lander with Flap

Thomas J. Horvath*, Tod F. O'Connell ®, F. McNeil Cheatwood§L Ramadas K. Prabhu*andStephen J. Alter "*NASA Langley Research CenterAbstractAerodynamic wind-tunnel screening tests were conducted 077 a 0.029 scale model of aproposed Mars Surveyor 2001 Precision Lander (70 deg half angle spherically blunted cone with aconical afterbody). The primary experimental objective was to determine the effectiveness of a singleflap to trim the vehicle at incidence during a lifting hypersonic planetary entry. The laminar forceand moment data, presented in the form of coefficients, and shock patterns from schlierenphotography were obtained in the NASA Langley Aerothermodynamic Laboratoo, for post-normalshock Reynolds numbers (based on forebody diameter) ranging from 2,637 to 92,350, angles ofattack ranging from 0 up to 23 degrees at 0 and 2 degree sideslip, and normal-shock density ratiosof 5 and 12. Based upon the proposed entry trajectory of the 2001 Lander, the blunt body heavy gastests in CF, simulate a Mach number of approximately 12 based upon a normal shock density ratio of12 in flight at Mars. The results from this experimental study suggest that when traditional means ofproviding aerodynamic trim for this class of planeta_ entry vehicle are not possible (e.g. offset c.g.),a single flap can provide similar aerodynamic performance. An assessment of blunt bodyaerodynamic effects attributed to a real gas were obtained by synergistic testing in Mach 6 ideal-airat a comparable Reynolds number. From an aerodynamic perspective, an appropriately sized flapwas found to provide sufficient trim capability at the desired L/D for precision landing, lnviscidhypersonic flow computations using an unstructured grid were made to provide a quick assessment ofthe Lander aerodynamics. Navier-Stokes computational predictions were found to be in veo' goodagreement with experimental measurement.NomenclaturebREF_ reference span of model (3-in)D model base diameter (3-in)Lp.EF reference length (3-in)M Mach numberP pressure (psi)r radius (in)Re Reynolds numberSREF model base reference area (in _-)T temperature (°R)o_ angle of attack (deg)C A axial-force coeff., axial force/q.SREF* Aerothermodynamics Branch, NASA Langley Research Center,Hampton, VA.§ Space Access & Exploration Program Office, NASA LangleyResearch Center, Hampton, VA.1"Lockheed Martin Engineering & Sciences Co., Hampton, VA.eCooperative education student, NASA Langley Research Center,Hampton, VA.Senior member, AIAACopyright ©2002 by the American Institute of Aeronautics andAstronautics, Inc. No copyright is asserted in the United Statesunder Title 17, U.S. Code. The U.S. Government has a royalty-freelicense to exercise all rights under the copyright claimed herein forgovernment purposes. All other rights are reserved by thecopyright owner.C _ rolling-moment coeff.,rolling-moment/q_SREFbR_F -Cm pitching-moment coeff.,pitching- moment/q_S REFLR_r:C N normal-force coeff.. Normal force/q SR_FCL_ A C_/A[3, (per degree)C,,_ A C,/A[3, (per degree)CY,I_ A Cy/AI3, (per degree)L/D lift to drag ratio_/ ratio of specific heatsq dynamic pressure (psi)p density (lbm/in 3)0 angle (deg)X_.g. c.g. locationSubscripts[3 sideslip angle, (degree)oo free-stream conditionsn model noses surface quantity, support stingsh Forebody shouldert, 1 reservoir conditions2 stagnation conditions behind normal shockw wallIntroductionThe next generation of Mars landers is beingdeveloped by NASA to provide a precision landingAmerican Instiute of Aeronautics and Astronautics