THE 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

Same experimental studies have been made to determine the general characteristics of rotor-blade flutter under hovering and simulated for-ward flight conditions by means of flutter tests of the rotor system of a l/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.nThe 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 signifi¬cance 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 oscil¬lation having a distinct frequency to a more random type of oscillation of comparable amplitude but without a well-defined frequency.