A Nonlinear Theory for a Hovercraft Moving over Regular Waves

Abstract

The equations governing the heaving and pitching of a hovercraft supported on two interconnected plenum compartments are integrated numerically to find the response as the craft passes over sinusoidal waves whose crests are normal to the direction of motion. When the flexible skirt around the plenum chambers comes into contact with the wave profile, it is assumed to collapse against the unyielding surface of the water. The scheme of integration is explained, and predictions of accelerations experienced on the craft are compared with those from a linearized theory developed earlier. For the range of wave heights considered, the accelerations indicated by the nonlinear theory are normally higher than those of the linear theory; save near pitching resonance, the two predictions differ by less than fifty per cent. For small wave heights, the ultimate response retains significant elements linked to the natural frequencies of pitch and heave.