Main rotor system for model helicopters

A main rotor blade for use on a model helicopter having a rotatable main rotor shaft to rotate the main rotor blade about a main rotor rotation axis in a steady-state main rotor blade plane of rotation when the main rotor blade rotation axis is perpendicular to the main rotor rotation axis, the main rotor blade being pitchable about a main rotor blade pitch axis, the main rotor blade comprising

• a blade root adapted to link to the main rotor shaft,
• a blade tip spaced apart from the blade root,
• a leading edge extending from the blade root to the blade tip,
• a trailing edge extending from the blade root to the blade tip and being spaced apart from the leading edge,
• an upper surface extending between the blade root, blade tip, leading edge, and trailing edge,
• a lower surface extending between the blade root, blade tip, leading edge, and trailing edge and spaced apart from the upper surface,
• an inboard section situated adjacent to the blade root, the inboard section having an inboard section chord line extending in a straight line from the trailing edge to the leading edge perpendicular to the main rotor blade pitch axis, the inboard section chord line having an inboard section chord length and being oriented relative to a steady-state main rotor blade plane of rotation to define an inboard section included angle, a thickness between the upper surface and lower surface of about 4% to 8% of the inboard section chord length, and an inboard section camber line extending from the trailing edge to the leading edge, midway between the upper surface and the lower surface, and perpendicular to the main rotor blade pitch axis, the maximum distance perpendicular to inboard section chord line between the inboard section chord line and the inboard section camber line is about 4% to 7% of the inboard section chord length, and
• an outboard section situated adjacent to the blade tip, the outboard section having an outboard section chord line extending in a straight line from the trailing edge to the leading edge perpendicular to the main rotor blade pitch axis, the outboard section chord line having an outboard section chord length and being oriented relative to a steady-state main rotor blade plane of rotation to define an outboard section included angle that is less than the inboard section included angle, a thickness between the upper surface and lower surface of about 8% to 11% of the outboard section chord length, and an outboard section camber line extending from the trailing edge to the leading edge, midway between the upper surface and the lower surface, and perpendicular to the main rotor blade pitch axis, the maximum distance perpendicular to the outboard section chord line between the outboard section chord line and the outboard section camber line is about 0% to 4% of the outboard section chord length.

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

• a main rotor shaft rotatable about a main rotor rotation axis,
• first and second main rotor blades linked to the main rotor shaft to rotate about the main rotor axis of rotation in a main rotor blade plane of rotation,
• means for pitching the first and second main rotor blades about first and second main rotor blade pitch axes, respectively,
• first and second stabilizer rotor blades linked to the main rotor shaft to rotate about the main rotor axis of rotation in a steady-state stabilizer rotor blade plane of rotation when the stabilizer rotor blade plane of rotation is perpendicular to the main rotor rotation axis, the first and second stabilizer rotor blades being linked to the first and second main rotor blades to pitch the first and second main rotor blades about the first and second main rotor blade pitch axes, respectively, and
• means for pitching the first and second stabilizer rotor blades about first and second stabilizer rotor blade pitch axes, respectively, each of the first and second stabilizer rotor blades having a leading edge, a trailing edge spaced apart from the leading edge, and a plurality of chord lines extending from the leading edge to the trailing edge perpendicular to the first and second stabilizer rotor blade pitch axes, at least one of the plurality of chord lines of the first and second stabilizer rotor blades being oriented to situate the leading edge above the steady-state stabilizer rotor blade plane of rotation and the trailing edge below the steady-state stabilizer rotor blade plane of rotation so that the steady-state stabilizer rotor blade plane of rotation is between the leading edge and the trailing edge.

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

• a main rotor shaft rotatable about a main rotor axis of rotation,
• first and second main rotor blades linked to the main rotor shaft to rotate about the main rotor axis of rotation in a main rotor blade plane of rotation,
• a pitch mechanism configured to pitch the first and second main rotor blades about first and second main rotor blade pitching axes, respectively,
• first and second stabilizer rotor blades linked to the main rotor shaft to rotate about the main rotor axis of rotation in a stabilizer rotor blade plane of rotation, the first and second stabilizer rotor blades being linked to the first and second main rotor blades to pitch the first and second main rotor blades about the first and second main rotor blade pitch axes, respectively, the first and second stabilizer rotor blades being formed to include stabilizer pivot rod-receiving channels,
• first and second stabilizer rotor blade extensions, each of the first and second stabilizer rotor blade extensions having a first end linked to the main rotor shaft and a second end connected to the first and second stabilizer rotor blades, respectively, and
• a stabilizer pivot rod extending through the stabilizer pivot rod-receiving channels formed in the first and second stabilizer rotor blades along first and second stabilizer pitching axes, respectively, the first and second stabilizer rotor blade extensions being spaced apart from the stabilizer pivot rod.

On a main rotor system for use on a radio-controlled model rotary wing aircraft having a main rotor blade extending radially from a main rotor hub and supported for rotation by a main rotor shaft to rotate in a main rotor blade plane of rotation substantially perpendicular to the main rotor shaft, a rotor blade comprising

• a blade root situated in proximity to the main rotor hub,
• a blade tip situated in spaced apart relation to the blade root at the distal end of the rotor blade,
• a blade length measured as the radial distance between the blade root and blade tip,
• a blade body extending radially between the blade root and the blade tip and transversely between a leading edge and a trailing edge, and having a primary configuration wherein the blade body lies substantially in the main rotor blade plane of rotation with the blade tip extending radially away from the blade root, the blade body being semi-flexible to bend during a crash landing of the radio controlled model rotary winged aircraft to a second configuration about a flex axis spacially offset from the main rotor blade plane of rotation, and
• the blade is returnable to substantially the primary configuration without repair for subsequent or continued operation of the model rotary winged aircraft.

A rotor blade for use on a radio-controlled model rotary wing aircraft including a rotatable main rotor having a main rotor blade extending radially from a main rotor hub and supported for rotation by a main rotor shaft to rotate in a steady-state main rotor blade plane of rotation substantially perpendicular to the main rotor shaft, the rotor blade comprising

• a blade root situated in proximity to the main rotor hub,
• a blade tip situated in spaced apart relation to the blade root at the distal end of the rotor blade,
• a blade length measured as the radial distance between the blade root and blade tip,
• a blade body extending radially between the blade root and the blade tip and transversely between a leading edge and a trailing edge, and having an inboard section adjacent to the blade root, an outboard section adjacent to the blade tip, and a transition section separating and connecting the inboard section and outboard section,
• the inboard section including an inboard airfoil having an inboard airfoil thickness, inboard airfoil camber and inboard airfoil chord line, the inboard airfoil chord line extending directly from the leading edge to the trailing edge and having an inboard airfoil chord length with the inboard airfoil thickness and inboard airfoil camber being measured as a percentage of the inboard airfoil chord length,
• the outboard section including an outboard airfoil having an outboard airfoil thickness, outboard airfoil camber, and outboard airfoil chord line, the outboard airfoil chord line extending directly from the leading edge to the trailing edge and having an outboard airfoil chord length with the outboard airfoil thickness and outboard airfoil camber being measured as a percentage of the outboard airfoil chord length, and
• the inboard airfoil camber expressed as a percentage of inboard airfoil chord length is greater than the outboard airfoil camber expressed as a percentage of outboard airfoil chord length and the inboard airfoil thickness expressed as a percentage of inboard airfoil chord length is less than the outboard airfoil thickness expressed as a percentage of outboard airfoil chord length.

A main rotor for use on a model helicopter, the main rotor comprising

• a main rotor shaft rotatable about a main rotor rotation axis,
• first and second main rotor blades linked to the main rotor shaft to extend radially outward from and substantially perpendicular to the main rotor shaft and to rotate with the main rotor shaft in a steady-state main rotor blade plane of rotation when the main rotor blade plane of rotation is perpendicular to the main rotor rotation axis, and
• a mechanism configured to pitch the first and second main rotor blades about first and second main rotor blade pitching axes, respectively, each of the first and second main rotor blades including a blade root linked to the main rotor shaft, a blade tip spaced apart from the blade root, a leading edge, a trailing edge spaced apart from the leading edge, a plurality of chord lines extending in a straight line between the leading edge and the trailing edge perpendicular to the first and second main rotor blade pitching axes, an inboard section situated adjacent to the blade root, and an outboard section situated adjacent to the blade tip, the inboard section having a first steady-state angle-of-attack defined as an included angle between one of the plurality of chord lines in the inboard section and the main rotor blade plane of rotation and the outboard section having a second steady-state angle-of-attack defined as an included angle between one of the plurality of chord lines in the outboard section and the main rotor blade plane of rotation, the first steady-state angle-of-attack being greater than the second steady-state angle-of-attack, wherein the one of the plurality of chord lines in the inboard section includes a first length and the one of the plurality of chord lines in the outboard section includes a second length that is shorter than the first length and wherein the inboard section includes a cupped-shaped cross-section between the trailing edge and the leading edge and the outboard section includes a flat cross-section between the trailing edge and the leading edge.

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

• a main rotor shaft rotatable about a main rotor rotation axis,
• first and second main rotor blades linked to the main rotor shaft to rotate about the main rotor axis of rotation in a main rotor blade plane of rotation,
• a mechanism configured to pitch the first and second main rotor blades about first and second main rotor blade pitch axes, respectively,
• first and second stabilizer rotor blades linked to the main rotor shaft to rotate about the main rotor rotation axis in a steady-state stabilizer rotor blade plane of rotation when the stabilizer rotor blade plane of rotation is perpendicular to the main rotor rotation axis, the first and second stabilizer rotor blades being linked to the first and second main rotor blades to pitch the first and second main rotor blades about the first and second main rotor blade pitch axes, respectively, and
• a mechanism configured to pitch the first and second stabilizer rotor blades about first and second stabilizer rotor blade pitch axes, respectively, each of the first and second stabilizer rotor blades having a leading edge, a trailing edge spaced apart from the leading edge, and a plurality of chord lines extending from the leading edge to the trailing edge perpendicular to the first and second stabilizer rotor blade pitch axes, at least one of the plurality of chord lines of the first and second stabilizer rotor blades being oriented to situate the leading edge above the steady-state stabilizer rotor plane of rotation and the trailing edge below the steady-state stabilizer rotor plane of rotation so that the steady-state stabilizer rotor plane of rotation is between the leading edge and the trailing edge.