STUDY THE EFFECT OF QUADRATIC BLADE SHAPE ON THE VERTICAL AUTOROTATION PERFORMANCE OF A SMALL SCALE MODEL HELICOPTER

Abstract

This paper presents the results of the numerical and experimental investigation of reducing the steady rate of descent of a typical small scale model helicopter. Power-off after hovering manoeuvre was picked for a case of study because of their critical induced velocity state. Contribution in every blade element in the effect of angle of attack, thrust and torque has been taken into consideration by blade element momentum theory for better results. In this analysis, test data of two types of blades with different driving region areas were obtained. The results of this study indicated that the expanding of the driving region area did reduce the steady rate of descent in vertical autorotation slightly but give lower rotor rotational speed compared to original shape blade. The study also had shown that zero collective pitch angle correction in the autorotation entry gives the best autorotation performance.