A Mathematical Model to Analyze the Static Stability of Hybrid (Aero- Hydrodynamically Supported) Vehicles.

Among the new concepts developed for high speed marine vehicles over the last two decades, the "aerodynamic alleviation" approach consists in using an aerodynamic surface to "alleviate" the weight sustained by the hydrodynamic lift. Such vehicle experiences aerodynamic and hydrodynamic forces of the same order of magnitude, therefore the dynamic models developed for airborne and waterborne vehicles are not suitable. Considering a vehicle having a high-speed prismatic planing hull and one or more aerodynamic surfaces, the authors propose two mathematical methods. The first one calculates the equilibrium attitude of the vehicle at a given speed and its numerical implementation has been used to undertake a parametric analysis of the influence of some configuration characteristics on performances. The second method analyzes the static stability of the HV. Starting from the dynamic analysis previously proposed by the authors, the characteristic polynomial of the HV dynamics is derived and a static stability criterion is proposed.