Study on Effect of Folding of Rotor Blades on Elastomeric Bearing in an Articulated Rotor System

In navy helicopters, folding of rotor blades is an operational requirement to minimize the helicopter footprint for stowage inside a hanger or within a constrained area on a ship deck. The folding of rotor blades can be carried out, either manually or automatically which mainly depends on operating environment, effort required and time available for blade folding operation. During folding of rotor blades, the rotor center of gravity shift from rotor center to aft of the helicopter based on the position of the rotor blades, and its effect on components/ systems need to be studied from various aspects such as asymmetric loading, blade deflection, structural clearance, tool design, ground handling, accessibility of fastening joints for folding, etc. The current study focuses on the effect of blade folding on the critical elastomeric bearing which act as a hinge for blade articulation in an articulated rotor system. Further, this study aims to arrive at necessary tooling configuration for controlled rate of blade folding. A motion simulation model of blade folding on the rotor system helps in the preliminary design and to arrive at an optimized design. In this study, an articulated rotor hub with elastomeric bearings is designed and modelled using the NX-UG software and main rotor blade folding simulation is carried out using motion simulation module.