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

摘要

Aerodynamic wind-tunnel screening tests were conducted on a 0.029-scale model of a proposed Mars Surveyor 2001 Precision Lander (70-deg half-angle spherically blunted cone with a conical afterbody). The primary experimental objective was to determine the effectiveness of a single flap to trim the vehicle at incidence during a lifting hypersonic planetary entry. The laminar force and moment data, presented in the form of coefficients, and shock patterns from schlieren photography were obtained in the facilities of the NASA Langley Aerothermodynamic Laboratory for postnormal shock Reynolds numbers (based on forebody diameter) ranging from 2.637 x 10~3 to 92.35 x 10~3, angles of attack ranging from 0 up to 23 deg at 0- and 2-deg sideslip, and normal-shock density ratios of 5 and 12. Based upon the proposed entry trajectory of the 2001 Lander, tests in the heavy gas CF4 simulate a Mach number of approximately 12 based upon a normal shock density ratio of 12 in flight at Mars. The results from this experimental study suggest that when the traditional means of providing aerodynamic trim for this class of planetary entry vehicle are not possible (e.g., offset e.g.), a single flap can provide similar aerodynamic performance. An assessment of blunt-body aerodynamic effects attributed to a real gas was obtained by synergistic testing in Mach 6 ideal air at a comparable Reynolds number. From an aerodynamic perspective, an appropriately sized flap was found to provide sufficient trim capability at the desired lift-to-drag ratio for precision landing. Inviscid hypersonic flow computations using an unstructured grid were made to provide an assessment of the viability of a flap to provide aerodynamic trim to the Lander. Subsequent Navier-Stokes computational predictions were found to be in very good agreement with experimental measurement.