The Lifting Line Theory is a quite efficient and accurate method to predict the 3D-flow around a wing of arbitrary shape (envelope and profile). The method presented here has been used for aerodynamic flow prediction of the AC72 catamaran, sailed at the AC 2013 and for the AC 50 catamaran for the AC 2017. It takes into account a main wing and a flap, both capable to be twisted. The shape of the wing can be changed for any possible application. The method is non-linear with respect to the 2D lift and viscous profile drag curves, which can have non-linear shape, thus allowing to predict flow separation of the 3D-wing from profile flow separation properties.
The method presented here includes an optimizer, which allows to maximize the driving force of the wing by setting main wing and flap sheet angles with the constraint of a maximum heeling and pitching moment.
The method is implemented as an Excel (C) file, making use of the Excel solver. It can be downloaded freely. A theoretical description of the method is included.
An additional implementation of this method is combined with a VPP of the foiling catamarans, so that the trim of the wing is optimized for maximum boat speed rather than driving force. This method is available on request.