Rapid estimation method for span load distribution on a rectangular wing planform using tabular data from lifting-line theory

The aim of this article is to present the rapid estimation method for span load distribution on a rectangular wing planform by using the tabular data from lifting-line theory. The data is generated by solving a monoplane equation to determine the coefficient of Fourier sine series that represents horseshoe strength distributed along the wingspan. Then the ratio of local lift coefficient to wing lift coefficient at the selected positions are determined and are presented in the tabular form. This set of data can be used to determine the spanwise lift distribution, the magnitude of total lift force and spanwise center of pressure location. The present method can be applied for a rectangular planform which has no sweep angle at quarter chord line and has no both geometric and aerodynamic twist along wingspan. The range of wing aspect ratio is 4 to 12 and the taper ratio is 0.1 to 1.0. Although the assumption of flow around wing planform is incompressible flow or at Mach number lower than 0.3, this present method can be extended to be used for subsonic compressible flow condition by using Prandtl-Glauert rule which is also discussed in this article. An illustrative example of the calculation process is presented in this article and the comparison of the result from the present method to the other calculation methods and experimental data are also discussed in this article.