Rotor system utilizing centrifugal deflection of non-radial blades

Claim 1

A HELICOPTER ROTOR SYSTEM ADAPTED TO AVOID CONTROL FORCE INSTABILITY ATTENDANT TO IN-PLANE OSCILLATIONS, COMPRISING A MAST; A PLURALITY OF BLADES WHOSE CHORDWISE CENTERS OF GRAVITY, TAKEN AT SUCCESSIVE CROSS-SECTIONS ALONG THE BLADE SPAN, ARE STATICALLY ALIGNED TO DEFINE A STRAIGHT TWIST AXIS; WHOSE CHORDWISE BENDING STIFFNESS EXCEEDS THEIR BENDING STIFFNESS PERPENDICULAR TO CHORDWISE; AND WHOSE NATURAL FREQUENCY OF IN-PLANE VIBRATION IS GREATER THAN THE NUMBER OF REVOLUTIONS IN THE SAME TIME PERIOD A DESIGN SPEED OF ROTATION; AN ARTICULATED HUB HOLDING THE BLADE ROOTS RIGIDLY AGAINST IN-PLANE LEADING AND LAGGING, SAID HUB INCLUDING FOR EACH BLADE A FLAPPING HING AND A FEATHERING HINGE OUTBOARD THEREOF AND AT THE INBOARD END OF THE BLADE, TWIST AXIS; MEANS TO APPLY PILOT CONTROL MOVEMENTS TO MOVE EACH BLADE ANGULARLY ABOUT ITS FEATHERING HINGE; AND ROOT RETENTION MEANS SECURING EACH BLADE TO THE ARTICULATED HUB TO POSITION ITS TWIST AXIS STATICALLY OUT OF RADIAL ALIGNMENT WITH THE MAST, SO AS TO BE BEHIND A RADIAL LINE FROM THE MAST THROUGH THE INTERSECTION OF THE FEATHERING AXIS WITH THE FLAPPING HINGE; WHEREBY CENTRIFUGAL FORCE ATTENDANT TO ROTATION DEFLECTS THE BLADES, WHEN PRESENTED AT A POSITIVE LIFTING ANGLE, FORWARD AND DOWNWARD TO A PREFERRED CENTER POSITION FOR OSCILLATORY VIBRATIONS.