Aerodynamic Characteristics Analysis of the High-Performance, Low-Altitude Solar-Powered Unmanned Aerial Vehicle M Solar-X using a Subsonic Wind Tunnel
Keywords:
aerodynamic characteristics, unmanned aerial vehicle, solar-powered UAV, subsonic wind tunnel, Computational Fluid Dynamics (CFD)Abstract
The purpose of this research was to investigate the aerodynamic characteristics of the M Solar-X fixed-wing UAV and the M Solar-X VTOL UAV through subsonic wind tunnel testing and to compare the results with those obtained from computational fluid dynamics: CFD simulations. The results indicated that the installation of the VTOL system did not significantly affect the lift coefficient of the aircraft model; however, it increased the drag coefficient by approximately 30–45%. Subsonic wind tunnel testing showed that both the M Solar-X and M Solar-X VTOL achieved maximum lift coefficients ranging from 1.4282 to 1.4609. The critical angle of attack was found to be between 10° and 12°, while the drag coefficient at zero angle of attack ranged from 0.03059 to 0.05018. In addition, the UAV exhibited a negative pitching moment derivative with respect to the angle of attack about the center of gravity, indicating positive static longitudinal stability. The increase in drag reduced the lift-to-drag ratio, which directly affects flight endurance and operational range. Nevertheless, the VTOL capability expands the flight envelope and enhances operational flexibility, particularly in confined operating environments. Furthermore, the results obtained from the CFD analysis were in good agreement with those derived from the subsonic wind tunnel tests, confirming the validity of the aerodynamic predictions. The aerodynamic characteristics identified in this study can serve as valuable reference data for future UAV design and related research.
References
Ansys Fluent. (2024). Ansys Fluent theory guide. Ansys Help Center. https://ansyshelp.ansys.com/public/account/secured?returnurl=/Views/Secured/corp/v242/en/flu_th/flu_th.html
BAE Systems. (2025). PHASA-35. https://www.baesystems.com/en/product/phasa-35#
Barlow, J. B., Rae, W. H., Jr., & Pope, A. (1999). Low-speed wind tunnel testing (3rd ed.). John Wiley & Sons.
Bertin, J. J., & Cummings, R. M. (2014). Aerodynamics for engineers (6th ed.). Pearson Education Limited.
Bierig, A., Nikodem, F., & Rothe, D. (2024). General design considerations for solar-electric high-altitude long-endurance aircraft. In International Council of the Aeronautical Sciences (Ed.), 34th Congress of the International Council of the Aeronautical Sciences (pp. 1-17). Curran Associates, Inc.
Choosinworasakul, V., Wongkamchang, P., Bamrungthai, P., & Pedchote, C. (2025). Camouflaged target tracking using a thermal imaging and a true color camera fusion [In Thai]. EAU Heritage Journal Science and Technology (Online), 19(2), 142–156. https://he01.tci-thaijo.org/index.php/EAUHJSci/article/view/275531
Coleman, H. W., & Steele, W. G. (2009). Experimentation, validation, and uncertainty analysis for engineers (3rd ed.). John Wiley & Sons.
Eiampan, T., Wongkamchang, P., Kosanwat, P., Ruaengmaneeya, N., & Thothong, W. (2022). Safety risk management of human factors in flight operations with the Royal Thai Air Force vertical take-off and landing solar power UAV according to the standards of the International Civil Aviation Organization [In Thai]. EAU Heritage Journal Science and Technology (Online), 16(2), 91–104. https://he01.tcithaijo.org/index.php/EAUHJSci/article/view/253492
Hull, D. G. (2007). Fundamentals of airplane flight mechanics. Springer.
Islam, S., Samsuzzoha Ara, S., & Islam, N. (2013). Unsteady solutions of thermal boundary layer equations by using finite difference method. Annals of Pure and Applied Mathematics, 3(2), 142-154. http://www.researchmathsci.org/apamart/apam-v3n2-6.pdf
Jitt-Aer, K., Thana, K., Chunsuparerk, D., Vejchasarn, P., & Phansenee, Y. (2023). Applying normalized difference vegetation index from UAV for fertilizer cost reduction in rice RD33 cultivation [In Thai]. Sripatum Review of Science and Technology, 15(1), 101-114. https://ph02.tci-thaijo.org/index.php/spurst/article/view/248431/169862
Kumar, G., Sepat, S., & Bansal, S. (2015). Review paper of solar powered UAV. International Journal of Scientific & Engineering Research, 6(2), 41-44. https://www.scribd.com/document/405292491/Review-paper-of-Solar-Powered-UAV
Malaver, A., Motta, N., Corke, P., & Gonzalez, F. (2015). Development and integration of a solar powered unmanned aerial vehicle and a wireless sensor network to monitor greenhouse gasses. Sensors, 15(2), 4072-4096. https://doi.org/10.3390/s150204072
Maleki, M. H. (2011). Conceptual design method for solar powered aircraft. In American Institute of Aeronautics and Astronautics (Ed.), 49th AIAA Aerospace Sciences Meeting (pp. 1-18). Curran Associates, Inc.
Marta, A., & Gamboa, P. (2014). Long endurance electric UAV for civilian surveillance missions. In International Council of the Aeronautical Sciences (Ed.), 29th Congress of the International Council of the Aeronautical Sciences (pp. 1-19). Curran Associates, Inc.
Noth, A. (2008). Design of solar powered airplanes for continuous flight [Doctoral dissertation, École Polytechnique Fédérale de Lausanne, Switzerland]. ETH. https://doi.org/10.3929/ethz-a-005745622
Royal Thai Air Force. (2025a). Royal Thai Air Force 20-year strategic plan (2018-2037), updated 2025 [In Thai]. https://drive.google.com/file/d/188l93jHLFbVPvY6tLLZONre3jfAP_5n_/view
Royal Thai Air Force. (2025b). RTAF white paper 2025 [In Thai]. https://welcome-page.rtaf.mi.th/web/content/61334?unique=6862447cee8f48244ec60c883a87b86541438f15
Ruenpakdan, C., Jiajan, W., & Rojnpisit, T. (2024). Design and aerodynamic analysis of vertical take-off and landing solar powered UAV [In Thai]. NKRAFA Journal of Science and Technology, 20(1), 1-21. https://ph02.tci-thaijo.org/index.php/nkrafa-sct/article/view/251811/170894
Sonkar, S., Kumar, P., Puli, Y. T., George, R. C., Philip, D., & Ghosh, A. K. (2023). Design & implementation of an electric fixed-wing hybrid VTOL UAV for asset monitoring. Journal of Aerospace Technology and Management, 15(4), 1-16. https://doi.org/10.1590/jatm.v15.1297
Umprechar, T., Jiajan, W., & Sukpimai, P. (2025). Conceptual design of high altitude pseudo-satellite [In Thai]. EAU Heritage Journal Science and Technology (Online), 19(3), 153–172. https://he01.tci-thaijo.org/index.php/EAUHJSci/article/view/279489
Versteeg, H. K., & Malalasekera, W. (2007). An introduction to computational fluid dynamics (2nd ed.). Pearson Education Limited.
