Longitudinal Motions and Stability of Two Hydro-Foil Systems Free to Heave and Pitch in Regular Waves
Technical Report,01 Aug 1960,31 Jan 1962
MINNESOTA UNIV MINNEAPOLIS MINNEAPOLIS United States
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Experimental measurements were made of the motions of two hydrofoil configurations free to heave and pitch in regular waves. The two configurations consisted of a dihedral V foil forward, flat foil aft, and dihedral V foils both fore and aft, and a flat foil near the center of gravity. The motions were measured in both head and following seas for a variety of wave characteristics and two towing velocities. The experimental results were compared with quasi-steady linear and nonlinear theory, and also unsteady linear theory. In general, agreement with the quasi-steady linear theory was satisfactory, although some improvement in the correlation was obtained by considering the effects of unsteadiness. Nonlinearities had little effect on the amplitudes of the oscillatory motions of the nonlinear equations. Experimental investigation of the inherent stability of both configurations in smooth water indicated that the damping was greater than predicted by the quasi-steady linear theory.