Numerical Results In numerical examples a is assumed to be 1 rad. Table 1 shows a comparison study of the total induced drag between the present method and two kinds of lifting-line theories. Two lifting-line theories are unable to predict the near-field induced drag. This result confirms the validity of the present analysis because the agreement of two kinds of induced drags is good. Figures 2a and 2b show the spanwise distributions of the sectional induced drags by the present analysis for the cases of Table 1. The sectional distributions of two methods are different near the wingtip of even the large aspect ratio elliptic wing. Figure 3 shows a comparison result of the total suction force for various values of k. Even the extended lifting-line theory will not estimate induced drag sufficiently at the values of k above about 0.25, that is, of an aspect ratio below about 6.4.