Smooth-Water Performance of a Surface Piercing Hydrofoil Boat Based on Rotating-ARM Test Results and Theory

摘要

Results of six-component, rotating-arm test measurements of force and moment on each foil of a 1/15-scale surface-piercing hydrofoil boat model are used as a basis for analyzing its smooth-water motions. Equations of motion are formulated and computer solutions obtained for the steady straight and turning flight characteristics, dynamic stability indices, and trajectory in entering a steady turn under unventilated flow conditions. Most of the required hydrodynamic coefficients are derived directly or indirectly from the test data. The experimental results show strong hydrodynamic bow-to-stern foil interactions which cause either stern foil ventilation near zero sideslip angle or a large reduction in stern foil vertical force. Linearized steady turning theory predicts a turning radius 14 percent smaller than that given by the non-linear motion equations for a rudder angle of 25 deg. Previous experience with surface ships and submersibles also shows that the neglect of non-linear effects causes steady-turning capabilities to be overestimated. (Author)