Effect of Control Stiffness and Forward Speed on the Flutter of a 1/ 10-Scale Dynamic Model of a Two-Blade Jet-Driven Helicopter Rotor.

摘要

Some experimental studies have been made to determine the general characteristics of rotor-blade flutter under hovering and simulated forward flight conditions by means of flutter tests of the rotor system of a 1/10-scale dynamic model of a two-blade Jet-driven helicopter. Tests were made for several configurations to evaluate the effect of variations in the blade-pitch-control stiffness and forward speed on the flutter speed. The results of the investigation showed that the flutter speed of the model blades was increased as the blade-pitch-control stiffness was increased and indicated that the structural blade modes of Primary significance with respect to flutter were the first torsion mode and the flapping mode. The results also showed that the rotor speed at flutter was reduced slightly as the tip-speed ratio was increased from a hovering condition and that the nature of the flutter motion was changed from a sinusoidal oscillation having a distinct frequency to a more random type of oscillation of comparable amplitude but without a well-defined frequency.