Soft inplane bearingless helicopter rotor

A soft inplane bearingless rotor to be rigidly mounted on a helicopter mast comprising:

• (a) a unitary yoke having a flat hub section adapted to be anchored to the end of said mast and having an even number of diametrically opposed blade-supporting arms extending from said hub section, each arm having a thin flapping section adjacent said hub section and a feathering section extending from said flapping section with blade attachments at the end of each of said arms, said arms comprising plural fiber reinforced composite ribs with inplane spacing;
• (b) a blade secured to each said blade attachment with cuff extending inboard to said flapping section;
• and
• (c) bearing structure interconnecting the inboard end of said cuff and said flapping section and including inplane resilient structure for soft inplane restraint of said blade.

A soft inplane bearingless rotor to be rigidly mounted on a helicopter mast comprising:

• (a) a unitary yoke having a flat hub section adapted to be anchored to the end of said mast and having at least three uniformly spaced radial blade-supporting arms extending from said hub section, each arm having a thin flapping section adjacent said hub section and a feathering section extending from said flapping section with blade attachments at the end of each of said arms, said arms comprising plural fiber-epoxy composite parallel ribs with predetermined inplane spacing and unified by a medial fiber-epoxy flange structure;
• (b) a blade secured to each said blade attachment with a cuff extending inboard to said flapping section;
• and
• (c) bearing structure interconnecting the inboard end of said cuff and said flapping section and including inplane resilient structure for soft inplane restraint and damping of said blade.

A soft inplane bearingless rotor to be rigidly mounted on a helicopter mast comprising:

• (a) a unitary yoke having a thick flat hub section adapted to be anchored to the end of said mast and having diametrically opposed blade-supporting arms extending from said hub section, each arm having a thin flapping section adjacent said hub section and a feathering section extending from said flapping section with blade attachments at the end of each of said arms, said arms including a plurality of fiber-epoxy parallel ribs extending span-wise and interconnected to maintain inplane spacing of said ribs;
• (b) means for securing a blade to each said blade attachments and for securing a cuff as to extend inboard to said flapping section;
• and
• (c) bearing structure interconnecting the inboard end of said cuff and said flapping section and including inplane resilient structure for soft inplane restraint of said blade.

A soft inplane bearingless rotor to be rigidly mounted on a helicopter mast with foldable blades comprising:

• (a) a unitary yoke having a flat hub section adapted to be anchored to the end of said mast and having diametrically opposed blade-supporting arms extending from said hub section, each arm having a thin flapping section adjacent said hub section and a feathering section extending from said flapping section with a pair of tangentially spaced blade bolt attachments at the end of each of said arms, said arms including a plurality of fiber reinforced composite parallel ribs extending span-wise with predetermined inplane spacing;
• (b) a blade secured to each said blade bolt attachments;
• (c) a cuff secured to said attachments and extending inboard to said flapping section;
• and
• (d) bearing structure interconnecting the inboard end of said cuff and said flapping section and including inplane resilient structure for soft inplane restraint of said blade through said cuff.

A soft inplane bearingless rotor to be rigidly mounted on a helicopter mast comprising:

• (a) a unitary yoke having a flat hub section adapted to be anchored to the end of said mast and having an even number of diametrically opposed blade-supporting arms extending from said hub section, each arm having a thin flapping section adjacent said hub section and a feathering section extending from said flapping section with blade attachments at the end of each of said arms, said feathering section formed of plural stacked loops of fiber-epoxy material forming inplane spaced ribs with said loops encircling said blade attachments on diametrically opposed arms;
• (b) a blade secured to each said blade attachments with cuff extending inboard to said flapping section;
• and
• (c) bearing structure interconnecting the inboard end of said cuff and said flapping section and including inplane yieldable structure for soft inplane restraint of said blade.

A yoke for a soft inplane bearingless rotor to be rigidly mounted on a helicopter mast comprising:

• (a) a flat hub section adapted to be anchored to the end of said mast;
• (b) an even number of diameterically opposed blade-supporting arms extending from said hub section;
• (c) each said arm having a thin flapping section adjacent said hub section and a feathering section extending from said flapping section;
• and
• (d) blade attachments at the end of each of said arms and said feathering sections including a plurality of looped fiber-epoxy material stacked to form a plurality of ribs spaced apart inplane with each said loop encircling said blade attachments on diametrically opposed arms.