Aerodynamic characteristics of a two-dimensional porous sail

A method is presented for the numerical analysis of the aerodynamic characteristics of a two-dimensional single-surface porous sail. In this analysis the authors apply a series of Jacobi polynomials to express the pressure distribution and chordwise shape, considering carefully leading-edge conditions. It is found that the aerodynamic stability of a sail increases with increasing porosity. The effects of porosity on the value of the life coefficient and the position of the centre of pressure are shown in diagrams as functions of angle of attack and of excess length of membrane over the chord length.