Numerical Study on the Transition Performance of a Scale Model Helicopter from Hovering to Vertical Autorotation

Abstract

Autorotation characteristics for typical scale model helicopter in terms of induced velocity, rate of descent, main rotor rotational speed, thrust and torque were studied. 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 thrust, torque and induced velocity has been taken in consideration by blade element momentum theory for better results. Newton second laws were used in kinematics analysis for enabling the rate of descent, helicopter acceleration and main rotor rpm to be prescribed. In this analysis, the results show all the autorotation characteristics fluctuated at the beginning then become constant at the end. This situation proved that transition from hovering to steady autorotation has been achieved.