Four degree-of-freedom maneuverability of an air cushion vehicle

A four degree-of-freedom mathematical model was established to investigate the maneuverability of an air cushion vehicle (ACV). The forces of aerodynamic, propellers and rudders were obtained by wind tunnel experiments. A series of constrained model experiments with horizontal planar motion mechanism (HPMM) were conducted to determine the hydrodynamics and the experiments were conducted over a wide range of operating conditions such as speed, drift angle, yawing angular speed and roll angle. A computer program was used to simulate the ACV turn capability and the results show that the ACV's turn trajectory is like a spiral curve with constriction radius. It is dangerous for the ACV to turn with big fixed rudder angles because of yaw instability or whipping. The wind influences much on the ACV's turning ability. No turn can be accomplished for fast tailwind.