Y. Hecht, O. Rand

The paper presents a theoretical investigation of the response of helicopter blades to a sharp collective increase in hover. The modeling deals with both main aspects of the problem: the spanwise distribution of the unsteady loads, and the corresponding structural dynamic response of the elastic blades and the rotor-fuselage system as a whole. The aerodynamic loads distribution is calculated by the definition and determination of the spanwise distribution of the aerodynamic equivalent mass, which is responsible for the time dependent development of the velocity induced by the trailing vortices. The structural modeling is based on the finite-element approach, and the equations of motion are derived using Lagranges equations. Due to the sharp changes in time, all terms containing time derivatives are retained in the equations which results in highly nonlinear expressions. A comprehensive investigation was performed to identify and quantify the role and the sensitivity of a variety of parameters. One conclusion is that for high command rates, the induced velocity exhibits relatively slow response and, therefore, the dynamic phenomena become predominant.

17th European Rotorcraft Forum 1991, Berlin

Conference Paper

englisch

21,0 x 29,7 cm, 12 Seiten

DGLR-Bericht, 1991, 1991-08, 17th European Rotorcraft Forum Proceedings; S.339-350; 1991; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

rotor blades, helicopters, structural dynamic analysis

Bestellbar

1991