The thesis deals with the change of direction of the lift force on a bent wing, which is often neglected in practice, since the wing is usually calculated with the small deformation theory. However, with this theory it is not possible to determine the deflection and direction of the lift force on strongly deformed wings accurately. Therefore we have derived a theoretical procedure based on a nonlinear Euler-Bernoulli beam model. The procedure is intended for a strongly bent elliptical wing, whose shape and thus the lift distribution is typical for gliders. Our calculations of the lift force along the entire wing were verified with XFLR5, a program for calculating the aerodynamic properties of the wing. The bending deformation equations were calculated numerically, taking into account that the load follows the deformation. Based on the angle of inclination at each point of the wing, we obtain the actual lift distribution as can be seen in reality. We have written a computer code that can solve the problem of the wing deformability for any type of aircraft under the conditions of our assumptions. With this code, any user can calculate and decide if the deformations are large enough for a given aircraft maneuver, and use our theory to get more accurate results.
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