The hydro-elastic stability of hydrofoil struts

Abstract

Hydrofoil struts, such as might be used for supporting a model in hydrodynamic experiments, are liable to failure through divergence or flutter. This makes the problem of designing a satisfactory strut particularly difficult if high speeds are required and if the struts must be kept thin to avoid cavitation. In the present report the theory developed to describe the aero-elastic stability of aircraft wings is applied to provide predictions of the speeds of onset of the two kinds of instability; in particular a simplified analysis of how the divergence speed depends on strut length and rake is included. The results of a series of experiments on the variation of divergence speed with strut length and on the variations of divergence speed and flutter speed with rake are presented. The agreement between theory and experiment is satisfactory.