Abstract: A helicopter rotor hub for use in an air-driven helicopter comprises a section of a spherical stainless steel ball attached to the end of a hollow rotor shaft. An air compressor within the helicopter supplies air to the hollow rotor shaft which discharges through it to hollow rotor blades which have discharge nozzles at the trailing edges on their tips. The sole support bearing for the blades is in the form of a cup-shaped concave graphite bearing which engages the stainless steel ball and to which the rotor blades are attached. The graphite provides a lubrication-free bearing surface and also provides a seal against air leakage.