Swashplateless Active Blade Pitch Control with a Mechanical Delta-3 Restraint Having an Instantaneous Blade Pitch-flap Coupling Response

An apparatus comprising:

• a hub configured to couple to a mast;
• a grip configured to couple to the hub and a rotor blade;
• a pitch actuator coupled to the grip and configured to change a pitch of the rotor blade relative to the mast;
• and
• a delta-3 restraint coupled to the pitch actuator, wherein the delta-3 restraint is configured to control the pitch of the blade relative to the mast when the pitch actuator fails, and
• wherein the delta-3 restraint provides an instantaneous blade pitch-flap coupling response.

A method comprising:

• providing a hub assembly comprising:
• a hub configured to couple to a mast;
• a grip configured to couple to the hub and a rotor blade;
• a pitch actuator coupled to the grip and configured to change a pitch of the rotor blade relative to the mast;
• and
• a delta-3 restraint coupled to the pitch actuator, wherein the delta-3 restraint is configured to control the pitch of the blade relative to the mast when the pitch actuator fails, and
• wherein the delta-3 restraint provides an instantaneous blade pitch-flap coupling response.