DESIGN AND DEVELOPMENT OF AN HELICOPTER ROTOR HUB AND ELASTOMERIC BEARING.

This paper presents recent advances in the field of elastomeric bearings for light helicopter rotor hubs. These bearings are spherical hinges able to withstand centrifugal and lateral forces while accomodating torsional, flap and lead-lag motions. The main problem encountered during the development has been service life. The successful way to solve it is presented. Test results obtained with different kinds of bearing are reviewed and discussed. At last the ″hydroflex″ technique, that is the use of a fluid inside the flexible bearing, is described. This new technique increases the service life.