PERFORMANCE CHARACTERISTICS OF THE BUSHIPS PARENT HYDROFOIL

The BUSHIPS Parent Hydrofoil has been tested at three depths of ommersion for a range of angle of attack from 4.67 to 14.67 degrees. The results indicate that two types of full cavities may be obtained with surface ventilation, i.e., when the supply of air is provided by a surface-piercing support strut with blunt trailing edge. The performance of the hydrofoil is shown to be radically different for these two types of cavities at otherwise identical operating conditions. It is shown that the overall performance of the hydrofoil is better using forced ventilation than it is with surface ventilation. It is also shown that the type of surface ventilation used for the BUSHIPS hydrofoil is not reliable, and that without major improvements, this type of hydrofoil-strut system cannot be used to support a hydrofoil boat. The test results indicate that the lift and drag values corresponding to the same angle of attack, speed and depth, of a hydrofoil designed for surface ventilation are very sensitive to the type of water in which the hydrofoil operates. The corresponding force values differed by 30 percent in two different fluid media. (Author)