Abstract
Control surfaces, such as airplane elevators or rudders may use symmetric airfoil shapes which are mostly based on single airfoil geometry. For the 2013 America's Cup sailboat competition rigid sails were specified, based on tandem symmetrical airfoils of equal chord. Because of the unique geometry of this combination and because none of the traditional two-element airfoils were designed for this application, a more suitable airfoil shape was sought. Furthermore, control surfaces such as the rudder are not designed for high lift, while the rigid sail studied here is expected to operate near a lift coefficient of one. A parametric study, using numerical methods, on the effect of different geometrical variables led to the development of an improved sail geometry, compared with the initial baseline shape. Therefore, the first objective of the present study is to validate those predictions for this particular application. Because of the large dimensions of the actual sail, its operating Reynolds numbers are high compared with the available wind tunnel facility. The conservative approach in this study is based on the assumption that the smaller Reynolds number tests provide a satisfactory validation for the higher Reynolds number sailing conditions.
Authors: Giovanni Lombardi (Cubit), Joseph Katz (San Diego State University), Maurizio Foresta (Università di Pisa)
Keywords: America's Cup, rigid sail, tandem airfoils, wind tunnel, aerodynamics, sailboat
31st AIAA Applied Aerodynamics Conference, San Diego
