"Rotor head system is one of the most important and critical parts of a helicopter. There are several configurations of rotor head system, namely, fully articulated, rigid, semi-rigid, and bearing-less. The goal of this thesis is to present a study on the design of a rotor head system for a helicopter in the weight class 200-250 kg having a single main rotor and one tail rotor.
Based on a survey of various rotor heads, articulated rotor head system has been chosen as the configuration for undertaking the design study. The rotor head includes many components like flapping link, feathering shaft, rotor hub, blade gripper, bearing housing, bolts, nuts, two roller bearings and a thrust bearing. These components have been design based on the centrifugal load acting on the rotor hub. Suitable material properties have been assigned in calculating the dimensions. The criterion for the failure of the components is yield stress. Using a factor of safety of 1.5, the parts have been designed.
The rotor head components are designed under static loading condition. The components viz., flapping link, feathering shaft, blade gripper, bearing housing and rotor hub have been designed considering their tensile as well as shear failure. The bolts have been designed on the shear failure criterion. Cap screws have been designed based on the tensile failure. Drive shaft has been designed based on the torsional rigidity criterion. In addition the bearings have been selected based on the load and life requirement.
The CAD model have been developed using the software Solidworks. The weight of the components has been estimated after assigning suitable material properties to the components."