ESDU 90013 gives a semi-empirical method for thin uncambered and untwisted wings with streamwise or pointed tips and sharp leading-edges and unswept sharp trailing-edges. It applies for angles of attack up to 60 degrees and for Mach numbers from 1.2 to 5. The method requires only the aspect and taper ratios, together with values at zero angle of attack of normal-force-curve slope and aerodynamic centre position which may be obtained from ESDU 70012. The method was developed from a correlation of published and unpublished experimental data for taper ratios less than 0.5 and aspect ratios of 0.5 to 4 while for taper ratios exceeding 0.5 the aspect ratios were from 0.5 to 2; however, for angles of attack less than 20 degrees, the aspect ratio went down to 0.2. It predicted the normal-force coefficient to within 10 per cent except at low angles of attack where the accuracy was determined by ESDU 70012 and was within 15 per cent, and gave aerodynamic centre position as a fraction of aerodynamic mean chord to within 0.05 which yielded a pitching moment coefficient, based on root chord, within 0.03. Although all the data are for monoplane wings, it is suggested the results will apply to a cruciform configuration in symmetric flight with one wing in the plane of symmetry. The use of the method is illustrated with a worked example.