Six Degrees of Freedom Free-flight Measurement in the VKI Longshot Wind Tunnel

Free-flight testing methodologies have shown superior capabilities to aerodynamic balances for testing space debris and analyzing proximal body separation scenarios in short-duration hypersonic wind tunnels. A free-flight testing methodology has been established for the VKI Longshot wind tunnel previously, and the present paper discusses the advancements of the measurement setup and the post-processing algorithms to facilitate six degrees of freedom trajectory and aerodynamic analyses. A second, vertical optical view is implemented in addition to the horizontal schlieren visualization applied exclusively during previous experiments. The coupling of the two perspectives permits the measurement of the models' spanwise displacement and the computation of the aerodynamic coefficients along all axes. Experiments with simple spherical and cuboid geometries were performed for fine-tuning the processing algorithms. The dual camera setup and the upgraded tracking algorithms proved good capabilities for tracking the objects' motion and the measured aerodynamic forces presented a good agreement with former experimental data and empirical correlations.