Helicopter Rotor Drive System Parts Catalog

A helicopter rotor drive system features a control system and rotary blades. The rotor system is the rotating part of a helicopter which generates lift and consists of a mast, hub, and rotary blades. The blades are attached to the hub using various nuts and bolts. There are three main types of rotor drive systems: semirigid, rigid, and fully articulated. The classifications are based upon how the motor blades are attached and move in accordance to the main rotor hub.

In semirigid rotor systems, two blades are attached to a central hub. The hub can tilt according to the main rotor shaft using a teetering hinge. The teetering hinge is significant as it allows one blade to flap up and the other to flap down. This decreases the lead and lag forces on the blades. Semirigid rotor systems are simple, however the downside is that the reaction to control input is not as quick as articulated rotor systems.

In rigid rotor systems the blade roots are rigidly attached to the rotor hub. As they do not have hinges, rigid rotor systems rely on the bending of the rotor blades. The blades are unable to flap or utilize lead and lag movements. Despite these factors, rigid rotor systems are relatively straightforward in design and principle. Rigid rotor systems are considered to be the happy medium between semirigid motor systems and fully articulated systems. A disadvantage of rigid rotor systems is the higher vibration levels that compromises the overall control and comfort of the helicopter.

Fully articulated rotor systems allow for more movement in the blades. The blades have lead/lag, independent flap capabilities and the ability to feather. Fully articulated rotor systems have two or more main rotor blades. As the rotor spins, each blade responds to inputs from the control system to enable aircraft control.

Newer rotor systems use elastomeric bearings, which are arrangements of rubber and steel that can allow motion in two axes. Compared to metal bearings, elastomeric bearings require less maintenance as they wear better.