Main rotor system for helicopters

A main rotor for use in a rotary winged model aircraft, the main rotor comprising

• a rotor hub assembly rotatable about a main vertical axis, and
• at least two main rotor blades, each main rotor blade extending in a radial direction from the rotor hub assembly and having a tip end positioned to lie in spaced-apart relation to the rotor hub assembly and a root end coupled to the rotor hub assembly for pivotably folding movement from an initial horizontal position perpendicular to the main vertical axis about a horizontal axis through a folding angle of about 90.degree., whereby forces transmitted to the rotor hub by the rotor blade during a crash-landing of a rotary winged model aircraft including the main rotor are minimized due to movement of the rotor blades through said folding angle, wherein the rotor hub assembly includes a rotatable rotor hub and a blade grip for each main rotor blade, each blade grip has an inner portion coupled to the rotor hub for pivotable movement about an auxiliary vertical axis in spaced-apart parallel relation to the main vertical axis and an outer portion, and the root end of each main rotor blade is coupled to one of the outer portions for pivotable movement relative thereto about a horizontal axis, each blade grip includes a flapping limit tab, each main rotor blade includes a flapping detent positioned to be engaged by the flapping limit tab on a blade grip coupled to said main rotor blade and configured to slip from said flapping detent allowing said main rotor blade to fold upward 90.degree. or more about the horizontal axis, thereby minimizing forces transmitted from the main rotor blades to the rotor hub.

A main rotor for use in a rotary winged model aircraft, the main rotor comprising

• a rotor rotation axis,
• a rotor hub supported for rotation about the rotor rotation axis in response to operation of an onboard motor drive unit,
• a plurality of rotor blades extending radially from the rotor hub, and
• rotor blade attachment means for connecting the rotor blades to the rotor hub, the rotor blade attachment means including folding means for pivotably mounting each rotor blade to the rotor hub to fold about a folding axis from an initial horizontal position perpendicular to the rotor rotation axis toward a folded vertical position through a folding angle of more than 6.degree. that is in excess of a flapping angle defined by angular movement of said rotor blade relative to the initial horizontal position while reacting to the aerodynamic and gyroscopic forces encountered by said rotor blade in flight, whereby forces transmitted to the rotor hub by the rotor blade during a crash-landing of a rotary winged model aircraft including the main rotor are minimized due to movement of the rotor blades relative to the rotor hub through said folding angle.

A main rotor for use on a rotary winged model aircraft, the main rotor comprising

• a rotor rotation axis,
• a rotor hub supported for rotation about the rotor rotation axis in response to operation of an onboard motor drive unit,
• a plurality of rotor blades extending radially from the rotor hub, and
• rotor blade pivot means for connecting each rotor blade to the rotor hub, the blade pivot means including lead/lag means for pivotably mounting each rotor blade to one of lead and lag about a vertical lead/lag axis and means for pivotably mounting each rotor blade to flap about a horizontal pivot axis through a limited flapping angle of 6.degree. or less during rotation of the main rotor about the rotor rotation axis and reaction of the rotor blade to the aerodynamic and gyroscopic forces encountered in flight and to fold about the pivot axis through a folding angle of more than 6.degree. that is in excess of the limited flapping angle, whereby forces transmitted to the rotor hub by the rotor blade during a crash-landing of a rotary winged model aircraft including the main rotor are minimized due to movement of the rotor blades through said folding angle.