Rotor assembly with high lock-number blades

An aircraft rotor assembly, comprising:

• a central hub;
• a plurality of rotor blades coupled to the hub for rotation with the hub about an axis, each blade having a Lock number of approximately 5 or greater;
• a lead-lag pivot for each blade formed by a flexure coupling the associated blade to the hub, each pivot being a radial distance from the axis and allowing for in-plane lead-lag motion of the associated blade relative to the hub, each pivot allowing for in-plane motion from a neutral position of at least 1 degree in each of the lead and lag directions;
• and
• a discrete flap hinge for each blade;
• wherein elastic deformation of the flexure produces a biasing force for biasing the associated blade toward the neutral position,
• wherein the biasing force is selected to achieve a first in-plane frequency of greater than 1/rev for each blade.

An aircraft rotor assembly, comprising:

• a central hub;
• a plurality of rotor blades coupled to the hub for rotation with the hub about an axis, each blade having a Lock number of approximately 5 or greater;
• a lead-lag pivot for each blade formed by a flexure coupling the associated blade to the hub, each pivot being a radial distance from the axis and allowing for in-plane lead-lag motion of the associated blade relative to the hub, each pivot allowing for in-plane motion from a neutral position of at least 1 degree in each of the lead and lag directions;
• and
• a gimbal configured to allow pivoting of the hub relative to the axis about flap axes perpendicular to the axis;
• wherein elastic deformation of the flexure produces a biasing force for biasing the associated blade toward the neutral position,
• wherein the biasing force is selected to achieve a first in-plane frequency of greater than 1/rev for each blade.