Refer to figure.
The four principal rotor hub designs are:

• Teetering
• Fully articulated
• Hingeless
• Bearingless

All designs must allow the blades to flap and feather, but not all require a lead-lad hinge. Freedom to feather is usually provided using feathering bearings and freedom to flap by flapping hinges.

The modern rotor head designs have replaced some or all the hinges and bearings with solid but flexible attachments points.

The hingeless rotor head design uses conventional hinges only for feathering. The other two movements, flapping and lead-lag, are accommodated by the rotor blades' flexible attachments to the hub, such as elastomeric bearings or plastic material (advanced composites and reinforced plastics).

Plastic materials can be engineered to provide the necessary elasticity and strength, allowing for simpler, more reliable, and lower-maintenance rotor head designs compared to traditional hinged systems.