Aerodynamic Characteristics and Development of the Aerodynamic Database of the X-34 Reusable Launch Vehicle

An overview of the aerodynamic characteristics and the process of developing the preflight aerodynamic database of the NASA/ Orbital X-34 reusable launch vehicle is presented in this paper. Wind tunnel tests from subsonic to hypersonic Mach numbers including ground effect tests at low subsonic speeds were conducted in various facilities at the NASA Langley Research Center. The APAS (Aerodynamic Preliminary Analysis System) code was used for engineering level analysis and to fill the gaps in the wind tunnel test data. This aerodynamic database covers the range of Mach numbers, angles of attack, sideslip and control surface deflections anticipated in the complete flight envelope. Nomenclature b Wing span C D Drag coefficient C L Lift coefficient C l Rolling-moment coefficient C m Pitching-moment coefficient C n Yawing-moment coefficient C Y Side-force coefficient h Height of the moment reference point above the ground plane, ft M Mach number a Angle of attack, deg b Angle of ..

Constrained Minimization of Smooth Functions Using a Genetic Algorithm

The use of genetic algorithms for minimization of differentiable functions that are subject to differentiable constraints is considered. A technique is demonstrated for converting the solution of the necessary conditions for a constrained minimum into an unconstrained function minimization. This technique is extended as a global constrained optimization algorithm. The theory is applied to calculating minimum-fuel ascent control settings for an energy state model of an aerospace plane. Introduction Genetic algorithms for optimization (refs. 1 to 4) are nonderivative, nondescent, randomsearch procedures for functional minimization, and their algorithmic structure is based on biological concepts. Familiar descent-type minimization algorithms construct a sequence of iterations, each of which modifies the independent variable vector from the previous iteration. Genetic algorithms, in contrast, construct a random sequence of generations in which a population of codings of bounded independent..

Stage Separation and Glideback Performance of a Partially Reusable Small Launch Vehicle, AIAA Paper

An integrated analysis is presented for ascent, stage separation and glide back performance of a small, partially reusable launch vehicle sized for a payload of about 330 lbs to a 150 nm polar orbit. The altitude margin was used a performance metric for the glideback performance. Aerodynamic databases for each of these three phases of flight were developed using a combination of engineering level code, free stream and proximity wind tunnel test data and Euler CFD results. The ascent and glideback trajectories were generated using POST and the stage separation simulation was done using the in-house software Sep-Sim as a front end to the commercially available multi-body dynamic simulation code ADAMS ®. The payload to the designated polar orbit was optimized subject to the constraints imposed by stage separation and adequate performance reserve for the glideback booster in addition to the usual ascent trajectory constraints. Nomenclature normal acceleration, g’s α angle of attack, deg ∆α relative difference in angle of attack, de

Simulation and Analyses of Staging Maneuvers of Next Generation Reusable Launch Vehicles

NASA has initiated a comprehensive stage separation tool development activity to address the technology needed for successful development and operation of next generation reusable launch vehicles. As a part of this activity, ConSep simulation tool is being developed. This paper discusses the application of this tool to the staging maneuvers of two-stage-to-orbit (TSTO) vehicles. Simulation and analyses are performed for two bimese TSTO concepts, one staging at Mach 3 and the other at Mach 6. The TSTO bimese vehicles used in this study are sized for international space station class payload. The proximity and isolated aerodynamic databases used in the simulation were generated using the data from wind tunnel tests conducted at NASA Langley Research Center. ConSep is a MATLAB–based front end to the commercially available ADAMS solver, an industry standard package for solving multi-body dynamic problems. Nomenclature α angle of attack, deg ∆α relative difference in angle of attack, deg CA, CN, axial and normal force coefficient CA,b, CN,b basic (isolated) axial and normal force coefficient CA,int, CN,int interference axial and normal force coefficients ∆CA,δ,∆C axial and normal force coefficient increments due to elevon deflection e N,δ e CL, CD lift and drag coefficients Cm pitching moment coefficient C mb basic (isolated) pitching moment coefficient ∆C m,int interference pitching moment coefficient Cm,δe pitching moment increment due to elevon deflection Cmd command δe elevon deflection, deg γ flight path angle, de