**3. Structural analysis**

To evaluate the reaction of different supports at the external loads present in the wind tunnel, a static structural analysis and a vibrational analysis were performed [finite element method (FEM)].

For the static structural analysis, the contribution of drag, lift, pitching moment, and lateral forces was taken into account. From this study, although it results that the external loads do not involve compromising stresses, strains, and displacements, it is necessary to highlight two critical points. The first one is that the bending angle due to the displacement at the free extremity, where the model will be connected, is often relevant, especially in scale 1:80. In all cases (circular and elliptic sections, scales 1:80 and 1:180), it is necessary to take into account this bending angle, with an accurate measurement, to have the exact inclination of the model. The second interesting consideration concerns the larger stress (Von Mises) concentrations present with the elliptic sting. The worse behavior of the elliptic shape is because it has a worse filling. In fact, to fit the same cables, it is necessary to reduce the thickness of the wall; otherwise the length of the major semi-axis would have been too large. Both problems are manageable, but they require attention.

With the frequency analysis, it was verified that the external excitation during the experiments is far enough from the resonance frequency of the supports. The main vibrational external disturbance for the stings is the frequency of the vortex shedding of the SOAR model. Thus, the utilization of an elliptic section is possible, but it needs more vigilance regarding the designing of the wall thickness with an increase of the overall dimensions.
