US4012169A — Rotor for rotating wing type aircraft

Claim 1

Independent Claim 270 words

A rotor for a rotating-wing craft comprising a driving shaft, a flat star-shaped rotor hub made of resin-reinforced glass fibres and substantially extending in a plane perpendicular to said driving shaft, said rotor having a central part adapted for being secured to the end of said driving shaft and a plurality of flat arms extending each from said hub central part substantially along a radial axis in said plane, said hub central part and flat arms having, in the direction perpendicular to said plane, respective thickness of substantially different values so that said central part is rigid and said flat arms are flexible in said direction, a same plurality of rotor blades having each a fork-shaped root part, disposed in closed relationship to the outer end of one of said hub arms, and having two arms extending substantially along the radial axis of the respective hub arm at a distance from the two faces of said flat arm respectively, first and second means for connecting the fork-shaped root part of each rotor blade to said hub central part and to the outer end of said hub arm respectively, said first and second connecting means being adapted for permitting resiliently limited rotations and sliding displacement of said blade root part around and along said radial axis in relation to said hub central part and arm, and said first connecting means being further adapted for transmitting centrifugal radial forces from said rotor blade directly to said rigid hub central part, whereby flapping movements of the rotor blades in said direction are permitted by the flexible hub flat arms and said connecting means.

Claim 2

Dependent Claim 270 words

A rotor for a rotating-wing craft comprising a driving shaft, a flat star-shaped rotor hub made of resin-reinforced glass fibres and substantially extending in a plane perpendicular to said driving shaft, said rotor having a central part adapted for being secured to the end of said driving shaft and a plurality of flat arms extending each from said hub central part substantially along a radial axis in said plane, said hub central part and flat arms having, in the direction perpendicular to said plane, respective thickness of substantially different values so that said central part is rigid and said flat arms are flexible in said direction, a same plurality of rotor blades having each a fork-shaped root part, disposed in closed relationship to the outer end of one of said hub arms, and having two arms extending substantially along the radial axis of the respective hub arm at a distance from the two faces of said flat arm respectively, first and second means for connecting the fork-shaped root part of each rotor blade to said hub central part and to the outer end of said hub arm respectively, said first and second connecting means being adapted for permitting resiliently limited rotations and sliding displacement of said blade root part around and along said radial axis in relation to said hub central part and arm, and said first connecting means being further adapted for transmitting centrifugal radial forces from said rotor blade directly to said rigid hub central part, whereby flapping movements of the rotor blades in said direction are permitted by the flexible hub flat arms and said connecting means.

Claim 3

Dependent Claim 103 words

A rotor according to claim 1, wherein a same plurality of apertures having each an inside edge and an outside edge is arranged in said hub central part substantially on the respective radial axes of said hub arms, the two arms of said forked-shaped root part of each rotor blade extending along the radial axis of the respective hub arm to the central part aperture on said radial axis, and said first connecting means comprises a spherical abutement having an elastically deformable member inserted between the outside edge of said aperture and the inner ends of the arms of the respective root part.

Claim 4

Dependent Claim 111 words

A rotor according to claim 2, wherein each blade comprises at least one longitudinal bunch of fibres material, said bunch being sub-divided, from a predetermined cross-section of the blade towards the end of the respective hub arm, into at least a top bunch and a bottom bunch diverging towards the hub, said top bunch and bottom bunch being disposed one above the other symmetrically of the respective hub arm, and at least one bridge-like member is disposed to extend through the respective aperture the hub central part and to interconnect the respective ends of said top bunch and bottom bunch, the respective deformable resilient member being attached to said bridge-like member.

Claim 5

Dependent Claim 56 words

A rotor according to claim 3, wherein the gap between the divergent top and bottom bunches is filled, in the part between said predetermined cross-section of the blade and the end of the respective hub arms, by a lightweight wedge-shaped block made of a low density material, said block being covered by a synthetic-resin-impregnated fabric covering.

Claim 6

Dependent Claim 152 words

A rotor according to claim 3, wherein each blade comprises two longitudinal bunches made of fibre material and disposed the one along the leading edge and the other along the trailing edge of the blade, said two longitudinal bunches being separated by a lightweight block of a low density material, each blade being wholly covered by at least one covering consisting of a synthetic-resin-impregnated glass fibre material, and wherein the top and bottom bunches into which each of said two longitudinal bunches of each blade is sub-divided towards the end of the respective hub arm, are further sub-divided to form two loops respectively disposed above and under the respective aperture in said hub central part, two sleeves being placed in said two loops respectively, a releasable pin extending through said two sleeves and through said bridge-like member, and lightweight blocks of a low-density material being further interposed between said sub-divided fibre bunches.

Claim 7

Dependent Claim 121 words

A rotor according to claim 1, wherein a frequency-adapter unit is mounted between the cylindrical end of each hub arm and the base of the fork-shaped root part of the respective blade, said frequency-adapter unit comprising a bow, in this box a spherical bearing with a swivel-joint ball slidably mounted on the cylindrical end of the respective hub arm, sheet-metal covers placed on the facing surfaces of the arms of said fork-shaped root part, at least one abutment disposed on each of said arms and formed by synthetic-resin-impregnated fabric layers for locking the respective sheet-metal cover along said radial axis, and visco-elastic plates which are respectively disposed between said box and said sheet-metal covers, and which are secured thereto by vulcanization.

Claim 8

Dependent Claim 30 words

A rotor according to claim 1, wherein a blade pitch control lever is coupled with at least one of the two arms of the fork-shaped root part of each blade.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1980-03-14	1980-09-13	1981-03-15	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1984-03-14	1984-09-13	1985-03-15	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1988-03-14	1988-09-13	1989-03-15	$7700.00	Window Closed / Lapsed

Rotor for rotating wing type aircraft

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