Journal of Aircraft
American Institute of Aeronautics and Astronautics
Closed-form relations are presented for estimating ratios of the induced-drag and lift coefficients acting on a wing in ground effect to those acting on the same wing outside the influence of ground effect. The closed-form relations for these ground-effect influence ratios were developed by correlating results obtained from numerical solutions to Prandtl’s lifting-line theory. Results show that these influence ratios are not unique functions of the ratio of wing height to wingspan, as is sometimes suggested in the literature. These ground-effect influence ratios also depend on the wing planform, aspect ratio, and lift coefficient.
Phillips, W. F., Hunsaker, D. F., “Lifting-Line Predictions for Induced Drag and Lift in Ground Effect,” Journal of Aircraft, Vol. 50, No. 4, pp. 1226 – 1233, July – August 2013.