The 'hammerhead fairing' (HHF) launcher configuration uses a payload fairing that has a larger diameter than the launch vehicle. This allows for larger payloads to be carried using the same launcher components. However, the HHF leads to high aerodynamic forcing in the transonic regime called buffeting. If unaccounted for, buffeting can lead to launcher failure. The flow phenomena associated with buffeting were investigated on the Vega-E launcher, which is currently being developed by the ESA, using Pressure Sensitive Paint (PSP) in the TST-27 tunnel.

PSPs are a relatively new flow measurement technique that allows for quantitative measurements of surface pressure levels in a non-intrusive manner. High spatial resolution, which is equivalent to using millions of pressure taps, can be achieved using PSP. This allows for CFD-like surface pressure resolution to be obtained from wind tunnel experiments. However, PSPs had previously never been successfully implemented in Delft. Therefore, a test set up was devised for experiments in the TST-27. The final implementation was found to have a pressure uncertainty of at most 2.5 kPa, with a spatial resolution of 0.088mm.

First, validation measurements were done on the Coe and Nute Model 11. The Model 11 is a common HHF test case in literature that is used to study the buffeting phenomenon. Results obtained in the TST-27 were compared to historical data and showed good matching when accounting for blockage. After the validation, measurements were taken on the Vega-E launcher at different Mach numbers and angles of attack to quantify the effects of each variable on the pressure field. Lastly, the impact of protuberances on the model was studied. The protuberances that were used mimic those that will be present in the full-scale launcher.