Stability analysis of a three-wings high-speed craft

A recent project for development of an innovative high-speed marine vehicle, SEALAB, poses a new problem in the dynamic stability of marine crafts. In fact, SEALAB is a three-wings concept ship that navigates at high speed in sea waves. The three-wings system consists of aero-hydro-foils and of a set of skids connected to a sophisticated suspension link. The ability of the vehicle to keep its stability and the desired trim at sea, depends on the lift and drag characteristics of the wings together with the link elastic and geometric properties. A mathematical model of the navigation mechanics at constant forward speed is developed enlightening its stability characteristics. This prototype model discloses interesting new phenomena in the field of aero-hydro-elasticity and it provides a useful guide for a safe concept design of the craft stability. The linearized model offers a closed form tool based on a Lyapunov analysis. However, the effectiveness of this approach is tested in the frame of a global nonlinear navigation simulator of the craft comparing the numerically observed instabilities with the ones predicted on the basis of the linearized model.