A., “ Application of the Vortex-Lattice Concept to General, Unsteady Lifting-Surface Problems,” AIAA Paper 1977-1157, 1977. G., “ Vortex Lattice Method for Calculation of Quasi Steady State Loadings on Thin Elastic Wings in Subsonic Flow,” Aeronautical Research Inst. and Youngren H., “ Athena Vortex Lattice User Manual, Version 3.26,” 2006. J., Vol. 54, Lecture Notes in Engineering, Springer-Verlag, New York, 1989, pp. 1–12. Drela M., “ XFOIL: An Analysis and Design System for Low Reynolds Number Airfoils,” Low Reynolds Number Aerodynamics, edited by Mueller T. S., Summary of Low-Speed Airfoil Data, Vol. 3, SoarTech Publ., Virginia Beach, VA, 1998. X., Stuttgarter Profilkatalog I, Friedrich Vieweg & Sohn, Braunschweig, Germany, 1981. E., Theory of Wing Sections, Dover, New York, 1959, Appendix IV. Results from the method, presented for unswept wings having various airfoils, aspect ratios, taper ratios, and small, quasi-steady roll rates, are shown to agree well with experimental results in the literature, and computational solutions obtained as part of the current work.
As an improvement from earlier low-order methods, this method also predicts the separation pattern on the wing. In this method, the flow separation due to stall is modeled in a vortex lattice framework as an effective reduction in the camber, or “decambering.” For each section of the wing, a parabolic decambering flap, hinged at the separation location of the section, is calculated through iteration to ensure that the lift and moment coefficients of the section match with the values from the two-dimensional viscous input curves for the effective angle of attack of the section. The method is intended for use in design, modeling, and simulation. A low-order method is presented for aerodynamic prediction of wings operating at near-stall and post-stall flight conditions.
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