THE FORCE, MOMENT, AND HINGE-MOMENT CHARACTERISTICS OF SURFACE-PIERCING DIHEDRAL HYDROFOILS.
STEVENS INST OF TECH HOBOKEN N J DAVIDSON LAB
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The report presents the results of an experimental and theoretical study of the forces acting on a fully-wetted, surfacepiercing dihedral hydrofoil, fitted with trailing edge hinged flaps. The tests cover a range of dihedral, flap deflection, and trim angles at several depths of submergence. Measurements include lift, drag, pitching, moment about the mid-chord point at the foil apex, and the flap hinge moment. The threedimensional lift data is reduced to equivalent sectional values with appropriate aspect ratio and depth correction factors, and shows good agreement with theoretical predictions for all aspect ratios and dihedrals tested. The effect of flap operation is linear in the flap deflection angle for the range of settings used. Drag data is found to be linearly dependent on the square of the lift coefficient, with the drag at zero lift a function of dihedral angle and aspect ratio. Values of the hinge moment coefficient for all dihedrals and aspect ratios are linear in the flap deflection angle, and results for the various test parameters indicates no direct dependence on aspect ratio. Author