Hydrodynamic Analysis on Sailing (4th Report) : Wind Tunnel Experiments on Yacht Sails

Abstract

Wind tunnel experiments on yacht sails were carried out at wind tunnel of Osaka University. The test section used for the present experiments is of closed type, measuring 1.8M×1.8m. Wind speed ranges from 7 to 10m/s. In order to keep sail shape realistic cloth sail models should be reasonably large. The wind tunnel wall effect can be serious. We made correction for it using blockage correction factor, ε. The ε is obtained through experiments for a number of rectangular wings and rigid sail models. We took "Flying Fifteen" class sail as a sample and measured its performance. The lifting-line theory calculation for a separate jib as well as mainsail is made. In case of jib alone, the theoretical result compares well with the measured data. For the mainsail, we need, however, some amount of zero-lift-angle correction to represent the disturbing effect of a mast.