Calculating the thrust of a propeller is complex and involves both theoretical and experimental methods. While model propellers have historically been tested and scaled, computational fluid dynamics (CFD) is now commonly used for preliminary designs. Free stream velocity is a critical factor in determining thrust, especially for applications like RC airplanes, where ensuring adequate thrust is essential. Resources like NASA's simplified framework and thrust calculators can provide initial estimates, but they may oversimplify the complexities involved. Engaging with RC enthusiast forums can offer additional insights and practical advice for specific configurations.