A Method for Improving the Inherent Stability and Control Characteristics of Helicopters

Abstract

The problem of helicopter control and stability is examined with a view to establishing whether satisfactory inherent stability and control characteristics may be achieved without major design modifications and without having resources to automatic control devices. I t is shown that the possibility does exist of improving both the damping and the static stability of a helicopter by a relatively minor modification of the blade mass and aerodynamic characteristics, together with the use of spring and viscous restraint in the control system. This should result in considerably improved blind-flying characteristics and a reduction in excessive control sensitivity without sacrificing maneuverability. The control characteristic of such an inherently stabilized helicopter is evaluated by means of the transient response characteristics to abrupt control manipulation.