Feasibility of non-rotating active lifting surface for helicopter vibration reduction

A feasibility study of the employment of a non-rotating active lifting surface for helicopter vibration suppression is presented. The lifting surface which is connected to the airframe is designed to produce loads that will interfere with the fuselage dynamics in a way that will reduce its vibratory motion. In order to produce realistic predictions of the lifting surface effectiveness, the study utilizes different types of experimental data. Shaking test results are used to tune the fuselage model. For this purpose, a careful tailoring of a simplified elastic fuselage model is carried out, and the resulting model is shown to be capable of simulating the structural dynamics response of a full-scale helicopter fuselage up to a fairly high number of elastic modes. In addition, measured vibratory response data from a full-scale helicopter fuselage in various flight conditions are used to establish a realistic estimation of the vibratory hub loads. The study simulates the effect of additional lifting surfaces of various sizes, locations and orientations, and examines their ability to reduce the vibratory response of the entire fuselage or at some preferred locations.