## 8 Conclusions  
The study of the current \"state of the art\" of adaptive wings systems capable of improving the overall performance at subsonic speeds of UAVs was investigated as part of the literature review of this paper. It is thought by the authors that the present validation methodology on adaptive UAV wings will further improve the knowledge in this field. In this paper, a new validation methodology was developed to improve UAV aerodynamic performance during the cruise flight, by means of the model design, fabrication, simulation, and model validation of an adaptive wing prototype for the UAV S45. An adaptive wing was designed and validated using the proposed multidisciplinary methodology to find its optimized wing shapes that are able to improve the lift and drag performance during cruising phase. The main objective of this article was to develop a validation framework for an adaptive wing.  
Aircraft design disciplines, airfoil shape optimization, computational simulations, and wind tunnel tests were integrated into this framework. The CFD models allowed us to obtain the aerodynamic performances of the wing equipped with an adaptive leading edge and trailing edge.  
The verification and validation of the CFD model with an accurate mesh grid and the area metric method were successfully performed. The simulation results obtained, with  
Figure 26: Area metric results for lift forces.  
Figure 25: Area metric results for drag forces.  
the specific flow conditions defined in the wind tunnel tests, accurately agree with the experimental studies.  
The authors have used the term \"New knowledge\" in the abstract as we believe that the MDO methodology and the CFD model validation presented in this study both correspond to \"a novel research outcome\" on improving the performance of adaptive wings.  
The results of the adaptive wing system can be seen in Figure 27, where the lift-to-drag ratios can increase compared to the S45 original wing shape value of \(L/D=3\). The wind tunnel results show the efficiency of the adaptive wing prototype in producing less drag and more lift, resulting in higher \(L/D\) values, depending on the configuration of the actuators. This prototype wing can produce an important lift-to-drag ratio without extra fuel consumption from the UAV's engine. The \(L/D=7.5\) for test #21 is at the maximum displacement of the actuators but within the safety structural parameters of the prototype.  
The low drag production and high lift-to-drag ratio (efficiency factor) of the adaptive wing will translate into a reduction in fuel consumption and an increase in the S45 effective range. Adaptive wing systems for UAVs are a promising technology and have become a major solution for multipurpose flight operations because they allow the aerodynamic potential of UAVs to be optimized by adapting the wing to several flight conditions, and they also result in climate improvement by fuel consumption minimization.  
M.F.S.: investigation, experimental tests, analysis, writing--original draft; R.M.B.: supervision, review and editing; G.G.: review. All authors have read and agreed to the published version of the manuscript.  
Canada Research Chairs NSERC Program; 231679.  
The authors would like to express their thanks to [PERSON] and [PERSON] for the donation of the Price-Paidoussis Open Return Subsonic Wind Tunnel at the LARCASE research laboratory at Ecole de technologie superieure. The authors gratefully acknowledge the financial support by the Natural Sciences and Engineering Research Council of Canada (NSERC).  
The authors declare no conflict of interest. The authors declare that they have no known competing financial interest or personal relationships that could have appeared to influence the work reported in this paper.