Utilizing CFD Coupled 6DOF to Study the Characterization and Scaling Properties of Tumbling Flight

A previously developed CFD-6DOF environment was utilized to examine the scaling effects on a tumbling aerodynamic missile body. The missile of interest develops a tumbling trajectory after an onset period where the missile initiates a rapid pitching motion due to its inherent unstable static margin. The study will focus on all parts of the flight trajectory, including the onset and tumbling regimes of the flight trajectory. The tumbling region of the flight is defined by highly transient unstable rotations about all three body axes. The scaling properties of Mach and Reynolds numbers matching and Froude matching simulations will be performed at two sub-scales and compared to a full-scale CFD-6DOF simulation. Comparisons between scales were performed with translational and rotational trajectories, aerodynamic coefficients, and developed key performance parameters designed to characterize tumbling dynamics, which enabled the validation of each sub-scale model and the various potential scaling effects that may be present in the system. The study found that the CFD-6DOF simulation for the experimentally used model compared favorably to the experimental data across 84 test flights. The study has found that scaling with either of the two methods can provide adequate representative results of the full-scale dynamics if Mach effects are accounted for during the tumbling onset period. Thus, further work is required to quantify and correct Mach effects at certain scales.