NASA required an aerodynamics model of a spent solid rocket booster (SRB) to predict trajectory and impact location of the Ares I first stage after separation. The software needed to be integrated into new simulations written in C. Marshall Space Flight Center (MSFC) had previously developed a solid rocket booster re-entry simulation for the Space Transportation System (the Space Shuttle). The simulation was written in Fortran, and the aerodynamics model was embedded in a single function with other parts of the flight dynamics model. It could not be extracted easily for reuse in another simulation.
The Aerodynamics Model for a solid rocket booster is a software implementation of the aerodynamic formulas used in the SRB re-entry simulation. The new implementation was written in C++ and is a self-contained software component that can be reused in any simulation program capable of linking with C++ code. The software allows multiple copies to run in the same program so that a simulation can use the software to simulate rockets with one, two, or more SRBs.
The aerodynamics model uses both static and damping (dynamic) coefficient terms to compute the aerodynamic forces and moments. The aerodynamics model is a function of the velocity vector, the angular velocity, Mach number, and density. The model allows the user to set the center of mass, and allows Monte Carlo dispersion of axial force, normal force, center of pressure, aerodynamic roll damping, and aerodynamic pitch and yaw damping.
This work was done by Michael Madden and Richard Grube of Langley Research Center, and Melissa A. Hill of Unisys Corporation. LAR-17871-1
