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This paper develops a theoretical solution for the problem of determining thin wing’s lift force while moving near flat surface (a screen). The solution is determined under the assumption of fluid being ideal and incompressible. The Chaplygin-Zhukovsky hypothesis of rear-edge-limited solution is taken into consideration. The solution of a problem is reduced to the Fredholm equation that is solved numerically. The generalization of the Zhukovski solution was obtained, which provides the lift force dependence on the altitude of the flight The behavior of the lift force is very peculiar: it increases on decreasing altitude above the rigid surface. The screen effect becomes essential on moving wing altitude being smaller than the wings length. The effect was detected experimentally before and gave birth to construction of a special flying vehicle named "ecranoplan". It is shown in the paper that the lift force could increase several orders of magnitude. This effect could be used in developing flying vehicles of high loading capacity, which could be used in the territories of smooth surface: savannas, steppes, deserts, lakes, swamps, etc. The effect could be used for developing vehicles for operation on other planets having not very dense atmosphere and relatively smooth surface (like Mars). Flights in such an atmosphere are energy consuming, while using the effect of lift force increase near the surface could be very effective. (C) 2011 Elsevier Ltd. All rights reserved.