| The objective of this research is to implement and validate a method to compute the induced drag of multiple lifting surfaces aircraft configurations. The lifting line theory serves as a fundamental basis to calculate the induced drag. It was used by Laurendeau to develop a methodology to solve for the minimum induced drag lift distribution of three lifting surfaces aircrafts; equations that were used as a starting point for this work. Implementation is made such that non-planar wing and user-defined spanload distributions could be analyzed. A curve-fitting methodology is developed to adapt mathematics to the input spanload distribution, and a correction is applied to the induced drag results so that the lift over the fuselage is taken into account. Minimum induced drag lift distribution is also obtained as per Laurendeau's methodology. Results for wing-body-winglet configurations show good concordance with computational fluid dynamics (CFD) with a precision of more or less two drag counts. This shows that a lifting line approach, once corrected for the fuselage effect and dihedral, can provide accurate induced drag results. However, due to the absence of proper comparative data for two and three lifting surfaces aircraft configurations, an in-depth validation remains to be done for such aircraft designs. To do so, an approach to obtain the Oswald efficiency factor from Euler CFD results is proposed. |
