## 5 Conclusions  
A scaled research prototype model was presented, representative of the static and dynamic behaviour and the geometry of a commercial aircraft wing. The experimental rig was equipped with a transparent fuel tank and was loaded vertically and released, aiming to achieve conditions similar to the loading experienced by the aircraft wings during the discrete gusts encounters. A numerical model developed based on 1 DOF data was presented and employed for the same cases studied experimentally. The focus of this work was placed on the comparative analysis between the 50% filling level case using tap water as the working liquid and the dry case with the added equivalent liquid mass. The freely decaying response of the system was measured at multiple points using accelerometers, and three measurement points across the fuel tank were used for the analysis.  
Evidence of substantial additional energy dissipation was shown in the first out-plane bending mode. Substantial increases in the damping ratio and corresponding decreases in amplitude were evident, starting with the second half of the first cycle of motion and further developing depending on the spanwise location. Correlation with previously obtained results for 1 DOF vertically sloshing systems, as well as video captures from the side of the fuel tank, indicated links between liquid sloshing patterns at various vertical acceleration amplitudes and the induced damping effects. A numerical model was presented based on a modal representation of the dry structure with calibrated nonlinear dry damping, coupled with a surrogate fluid model interpolated from experimental 1 DOF data. The model was shown to predict the induced damping effects at all amplitudes, provided that corrections are made for the initial sloshing development region. The low amplitude regimes were modelled correctly if similar sloshing patterns that promote liquid-tank roof slamming were considered.  
The results shown in this work represent an initial assessment of some of the sloshing tests conducted on the MiniWoT specimen and indicate important liquid sloshing-induced effects manifested in the first bending component. The addition of 50% liquid inside the system led to significantly higher energy dissipation rates. The tests presented here also indicate and motivate planned future directions of study, such as the influence of the spanwise position of the liquid, filling level and tank geometry.  
Conceptualisation, F.G., J.E.C., B.T. and T.C.S.R.; methodology, L.C.; software, J.J.D.C. and L.C.; formal analysis, L.C.; investigation, L.C.; writing--original draft preparation, L.C. and J.J.D.C.; writing--review and editing, B.T., J.E.C., T.C.S.R. and L.C.; visualisation, L.C. and J.J.D.C.; supervision, J.E.C. and B.T.; project administration, F.G.; funding acquisition, F.G. All authors have read and agreed to the published version of the manuscript.  
The research leading to these results was undertaken as part of the SLOWD project, which has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 815044.  
Not applicable.  
The experimental data that was used in this work can be accessed at: [[http://canal.etsin.upm.es/ftp/SLOWD_DATABASE/case_1/index.html](http://canal.etsin.upm.es/ftp/SLOWD_DATABASE/case_1/index.html)]([http://canal.etsin.upm.es/ftp/SLOWD_DATABASE/case_1/index.html](http://canal.etsin.upm.es/ftp/SLOWD_DATABASE/case_1/index.html)), accessed on 1 August 2022.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.