US3578877A - Rotor construction with elastic interconnection of opposite blades - Google Patents

Rotor construction with elastic interconnection of opposite blades Download PDF

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Publication number
US3578877A
US3578877A US735956A US3578877DA US3578877A US 3578877 A US3578877 A US 3578877A US 735956 A US735956 A US 735956A US 3578877D A US3578877D A US 3578877DA US 3578877 A US3578877 A US 3578877A
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United States
Prior art keywords
rotor
head
blade
endless
blades
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Expired - Lifetime
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US735956A
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English (en)
Inventor
Karlheinz Mautz
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Bolkow GmbH
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Bolkow GmbH
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Publication date
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Publication of US3578877A publication Critical patent/US3578877A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/32—Rotors
    • B64C27/327—Retention means relieving the stress from the arm, e.g. tie-bars

Definitions

  • a four blade rotor construction for helicopters includes means for rotatably mounting each blade at equally spaced angular locations around the rotor hub. Diametrically opposed rotor blades are connected with each other by torsion elastic bands or endless members which are stretched across the center of the rotor head with one of the bands being arranged to pass through and intersect the other.
  • the endless bands are formed of laminations of torsion elastic bands and the laminations of one of the bands which connects one pair of blades are arranged in a substantially vertical orientation and the laminations of the other band which interconnects the two adjacent blades are arranged in a substantially horizontal plane.
  • the clearance between the two band loops at the center of the rotor head is such that collective and cyclic pitch controls are possible.
  • Rotors for helicopters which include traction laminations of a pack of laminations of an interconnecting band which is associated with a pair of rotor blades.
  • the laminations are arranged in' alternating layers which are separately centrally connected to a bolt arranged coaxially to the axis of the rotor head.
  • each rotor blade is to have, for a collective incidence in range of V gi collectiue +166 1 and cyclic incidence range of cyclicthis results in a total incidence range of -l1+27, hence 38.
  • This incidence range is transmitted to the pack of lamination and twists the latter or half a lamination length so that the specific torsion is M2 or D L K 3)
  • the maximum specific angle or twist is achieved with full collective and cyclic incidence in a positive direction and is For constructional and aerodynamicreasons, it has beenattempted to keep the rotor head diameterand the length of the laminations as small as possible. But since. the specific torsion must not exceed a maximum admissible value, this value. becomes the quantity determining the dimensions of the rotor head under certain conditions. A reduction of the specific torsion is only possible in the rotors of the known or suggested types by lengthening the laminations.
  • an improved helicopter-rotor is provided by connecting opposite pairs of rotor blades with laminated bands constructed so that specific torsion is considerably reduced and thusit'is possible to use bands with shorter laminations or the fatigue strength of the laminations of conventional length can be considerably increased.
  • the problem is solved in accordance with the invention by using laminations which are constructed as portions of endless stretched loops or bands.
  • the laminations of one band connect one pair of blades and are arranged substantially ina vertical orientation whereas the laminations of the other band connects the adjacent pair of bladesand they are arranged in a horizontal plane and conducted through the loop of the vertical laminations.
  • the clearance of the two loops and the lamination width are so tuned to each other that both collective and cyclic pitch controls are possible without impairing the respective crossed laminations. Because of such an arrangement, the cyclic pitch no longer contributes to the torsion of the laminations. Since a positive cyclic angle of incidence of a rotor blade always corresponds to an equal nega tive cyclic angle of incidence of the opposite rotor blade, the entire pair of rotor blades including the pack of laminations is tipped in a cyclic pitch control about the axis of the angular adjustment.
  • the value of the torsion is at the same time the value of the maximum specific angle of twist.
  • the specific. angle of twist can be further reduced in accordance with another feature of the invention by arranging each rotor blade so that it has an angle of incidence which is approximately in the center of the entire collective incidence range. From this fixed presetting each blade can be turned by the same amount corresponding to half the collective incidence range in a positive and in a negative direction. Thus, the specific angle of twist of the pack of laminations is reduced by half, but it can appear in both directions of twist.
  • the tension of the laminations can be adjusted and readjusted during assembly because of the use of fastening devices which permit a shift of position of each rotor blade and the securing of the rotor blade in its suspension sleeve free from play.
  • spring elements are provided which bear on the rotor head and on the blade sleeve.
  • each pack of laminations can also consist of a number of fitted loops or of a long band wound in several layers. All elastic materials with sufficient prolonged alternating strength stress, for example, spring steel or fiber reinforced plastics may be used for the lamination material.
  • Another object of the. invention is to provide an improved rotor head construction for helicopters wherein the rotor blades are mounted in sleeves at their roots for rotation at respective fixed locations'on the rotor head and wherein the rotor head is hollow to provide passage for endless bands which interconnect the roots of opposing rotor blades,. and wherein the bladesmay be adjustably secured in positionzby interconnecting or locking sleeve elements.
  • a further object of the invention is to provide a rotor head for a helicopter which is simple in design, rugged in construction and economical to manufacture.
  • FIG. is a partial sectional view on an enlarged scale of a pack of laminations forming the connecting bands.
  • the invention embodied therein comprises a four blade rotor construction for helicopters, which includes a rotor shaft 1 which is secured by means of bolts 2 to a rotor head 3 for rotation therewith.
  • the rotor head 3 carries a number of rotor arms having bearing sleeves 4 corresponding to the number of rotor blades 9.
  • Each blade 9 carries a blade root sleeve 5, which is secured to the blade by one or more securing bolts 6.
  • the blade root sleeve 5 extends into the associated bearing sleeve 4 and is rotatably supported therein at two axially spaced locations on roller bearings 7 and 8.
  • the bearings 7 and are arranged as far apart as possible in order to provide an adequate supporting force for each blade and to accommodate forces originating from the swinging and striking movements of the blades.
  • the rotor head 3 includes four equally spaced bearing sleeves 4 and each two opposing blade root sleeves which are rotatably supported therein are connected together by packs of laminations designed as loops or endless bands 10 and 18.
  • each blade root sleeve 5 carries a clamping ring 12, which is secured by a wedge 13 against rotation in respect to its associated root sleeve.
  • the clamping carries a cross bolt or loop-holding member 11 around which each loop 10 or 18 is directed.
  • An initial stress can be imparted to the loop 10 by adjusting a retaining nut 14 which is threaded on the clamping ring 12 and which bears against a collar 15 of the blade root sleeve 5.
  • the blade root sleeve 5 is pulled by the tightened loop 10 by the threading of the retaining nut 14 and stresses one side of a cup spring 17.
  • the spring 17 contacts an axial bearing 16 arranged at the end of the root sleeve and bears at its opposite or inner end against the rotor head 3.
  • the cup spring 17 ensures centering, free from play, of the two opposing blade angle sleeves 5, 5 with respect to the axis of rotation of the rotor even at full rotor speed when the laminations of the bands 10 are expanded by centrifugal forces.
  • two crossed loops or bands 20 and 21 are arranged in the untwisted state with the loop 20 disposed in a generally vertical orientation or plane and the loop 21 in a horizontal orientation.
  • the loop 21 passes through the loop 20 and the breadth and width of the loops are so selected that the loops do not interfere with each other in their movement in all collective and cyclic blade angles.
  • loop members 30 and 31 are shown as schematically connecting blades 34 and 35 and 32 and 33, respectively.
  • the blades 32, 33, 34 and 35 are arranged so that they do not have any fixed setting angle 8,.
  • the rotor blades 32 and 33 connected with the loop 30 assume an angle of incidence 8 determined by the inclination of the loop 30.
  • rotor blade 32 is imparted with a positive incidence angle and rotor blade 33 has a negative incidence angle.
  • the rotor blades 34 and 35 are indicated as not having any fixed incidence angle settings.
  • the loops 40 and 41 are shown as being schematically connected between blade paths 43 and 45 and 42 and 44, respectively.
  • the position of the loops 40 and 41 corresponds to the position where collective pitch control is effected.
  • All rotor blades 42, 43, 44 and 45 are set by the same positive angle 5 Both the loop 40 and loop 41 twist by the same amount.
  • the pack of laminations for a loop member generally designated 20 advantageously comprises steel laminations 50 between which are inserted intermediate layers of tetrafiuoroethylene 51.
  • the material 51 is of less friction than the material of the laminations 50in order to reduce deterioration of the laminations by friction.
  • a four blade rotor for helicopters comprising, a rotatable rotor head, four rotor blades symmetrically carried by said rotor head for rotation therewith about a central head axis and having root portions rotatably supported in said head for blade angle variation, and first and second endless laminated torsion-elastic loop members connecting the root portions of respective diametrically opposed rotor blades, said first endless laminated loop member passing entirely through said second endless laminated loop member, means rotatable mounting each of said blades to said rotor head, and spring means between said mounting means and said rotor head for centering each of said blades relative to said rotor head free of play.
  • a four blade rotor for helicopters comprising a rotatable head having four angularly symmetrically arranged and radially opening receiving sleeves for the respective rotor blades, means rotatably mounting said head for rotation about a substantially central axis, a rotor blade having a blade root sleeve rotatable mounted in each of said receiving sleeves, a clamping ring carried in said receiving sleeve and having a bolt member extending across the axis of said blade, means securing said clamping ring to said receiving sleeve for rotation with said receiving sleeve and said blade for varying the pitch angle of said blade, first and second endless loop members engaged around said bolt members of respective diametrically opposed rotor blades, said first and second endless loop members intersecting centrally within said rotor head and one of said first and second endless loop members passing through the other, a retaining nut threaded over said retaining ring and bearing against said root sleeve, said nut being threaded to
  • a four blade rotor construction according to claim 2, wherein said rotor head has a ledge abutment at the interior of each of said receiving sleeves, the root sleeves of each of said blades being spaced from said ledge abutment, and spring means disposed between said root sleeve and said ledge abutment and centering each of said root sleeves around said head free of play.
  • a four blade rotor construction according to claim 2, wherein said means mounting said root sleeve within said rotor head receiving sleeve comprises two axially spaced roller bearing sets.
  • a four blade rotor for helicopters comprising a rotatable rotor head, four rotor blades symmetrically carried by said rotor head for rotation therewith about a central head axis and having root portions rotatably supported in said head for blade angle variation for rotation about axes lying in substantially a common plane, and first and second endless laminated torsion-elastic loop members connecting the root portions of respective diametrically opposed rotor blades, said first endless laminated loop member passing entirely through said second endless laminated loop member, said first endless laminated loop member having laminations which are arranged substantially in a vertical plane, said second endless laminated loop member having laminations which are arranged in a substantially horizontal plane.
  • a four blade rotor for helicopters comprising a rotatable rotor head, four rotor blades symmetrically carried by said rotor head for rotation therewith about a central head axis and having root portions rotatably supported in said head for blade angle variation for rotation about axes lying in substantially a common plane, first and second endless laminated torsionelastic loop members connecting the root portions of respective diametrically opposed rotor blades, said first endless laminated loop member passing entirely through said second endless laminated loop member, and means carried by each of said rotor blades adjacent their root portions for adjustably connecting and tensioning the associated first and second endless laminated loop members.
  • a four blade rotor for helicopters comprising a rotatably rotor head, four rotor blades symmetrically carried by said rotor head for rotation therewith about a central head axis and having root portions rotatably supported in said head for blade angle variation for rotation about axes lying in substantially a common plane, first and second endless laminated torsionelastic loop members connecting the root portions of respective diametrically opposed rotor blades, said first endless laminated loop member passing entirely through said second endless laminated loop member, a bolt member extending across the axis of each of said blades with which said respective ones of said first and second endless laminated loop members are engaged, and means adjustably positioning said bolt member on each of said blades,
  • a four blade rotor for helicopters comprising a rotatable rotor head, four rotor blades symmetrically carried by said rotor head for rotation therewith about a central head axis and having root portions rotatably supported in said head for blade angle variation for rotation about axes lying in substantially a common plane, first and second endless laminated torsionelastic loop members connecting the root portions of respective diametrically opposed rotor blades, said first endless laminated loop member passing entirely through said second endless laminated loop member, a sleeve having a cross bolt therethrough, means adjustably mounting said sleeve in respective ones of each of said root portions for radial inward and outward adjustment, said first and second endless laminated loop members being looped over corresponding diametrically opposite cross belt bolts of said blades.
  • a four blade rotor for helicopters comprising a rotatable rotor head, four rotor blades symmetrically carried by said rotor head for rotation therewith about a central head axis and having root portions rotatably supported in said head for blade angle variation for rotation about axes lying in substantially a common plane, and first and second endless laminated torsion-elastic loop members connecting the root portions of respective diametrically opposed rotor blades, said first endless laminated loop members passing entirely through said second endless laminated loop member, said first endless laminated loop member extending substantially vertically and having horizontal lamina, said second endless laminated loop member extending horizontally and having substantially vertical arranged lamina.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Springs (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Laminated Bodies (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
US735956A 1967-07-11 1968-06-04 Rotor construction with elastic interconnection of opposite blades Expired - Lifetime US3578877A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEB0093415 1967-07-11

Publications (1)

Publication Number Publication Date
US3578877A true US3578877A (en) 1971-05-18

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US735956A Expired - Lifetime US3578877A (en) 1967-07-11 1968-06-04 Rotor construction with elastic interconnection of opposite blades

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US (1) US3578877A (enrdf_load_stackoverflow)
DE (1) DE1531359B1 (enrdf_load_stackoverflow)
ES (1) ES356058A1 (enrdf_load_stackoverflow)
FR (1) FR1559400A (enrdf_load_stackoverflow)
GB (1) GB1196318A (enrdf_load_stackoverflow)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3879153A (en) * 1974-01-07 1975-04-22 Gerald L Breuner Attachment for rotor hub and pairs of blades
US3893788A (en) * 1973-02-06 1975-07-08 Bendix Corp Flexible coupling
US4153390A (en) * 1976-08-25 1979-05-08 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschrankter Haftung Helicopter rotor structure
US4163630A (en) * 1976-08-25 1979-08-07 Messerschmitt-Bolkow-Blohm Gmbh Helicopter rotor structure
US4183718A (en) * 1976-12-11 1980-01-15 Messerschmitt-Bolkow-Blohm Gmbh Rotor for a rotary wing aircraft
US4243359A (en) * 1978-01-18 1981-01-06 Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter Haftung Rotor structure, especially for hingeless rotary wing aircraft
US4251188A (en) * 1977-12-17 1981-02-17 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschraenkter Haftung Four-blade rotor, especially for helicopters
US4299539A (en) * 1977-11-30 1981-11-10 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschraenkter Haftung Four-blade rotor, especially for helicopters
US5110260A (en) * 1990-12-17 1992-05-05 United Technologies Corporation Articulated helicopter rotor within an improved blade-to-hub connection
US5474424A (en) * 1991-07-03 1995-12-12 Aerospatiale Societe Nationale Industrielle Rotorcraft rotor head, which is rigid in drag and articulated in pitch and flapping
WO2015183658A1 (en) * 2014-05-30 2015-12-03 Sikorsky Aircraft Corporation Structurally efficient pin wrap
US10562608B1 (en) * 2017-05-25 2020-02-18 Amazon Technologies, Inc. Variable pitch mechanisms for propeller blades using linear actuation
US11021234B1 (en) 2017-05-25 2021-06-01 Amazon Technologies, Inc. Variable pitch mechanisms for propeller blades using a compound gearbox

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2722250A1 (de) * 1977-03-23 1978-11-23 Messerschmitt Boelkow Blohm Rotor eines drehfluegelflugzeugs
GB2122708B (en) * 1982-07-01 1985-09-25 Dunlop Ltd Improvements in or relating to link means

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2137952A (en) * 1936-06-25 1938-11-22 Walter W Rothenhoefer Airplane
US2495434A (en) * 1946-05-17 1950-01-24 Joy Mfg Co Variable pitch propeller
FR1334446A (fr) * 1961-06-28 1963-08-09 Bolkow Entwicklungen Kg Articulation sans frottement
US3228481A (en) * 1964-04-24 1966-01-11 Bendix Corp Tie bar bushing
US3249161A (en) * 1964-12-02 1966-05-03 Karl E Schoenherr Feathering controllable pitch propeller
US3384185A (en) * 1967-06-02 1968-05-21 Aerojet General Co Rotor hubs
US3434899A (en) * 1961-11-06 1969-03-25 Bendix Corp Laminated coupling
US3470962A (en) * 1967-02-07 1969-10-07 Westland Aircraft Ltd Rotor heads for rotary wing aircraft

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2137952A (en) * 1936-06-25 1938-11-22 Walter W Rothenhoefer Airplane
US2495434A (en) * 1946-05-17 1950-01-24 Joy Mfg Co Variable pitch propeller
FR1334446A (fr) * 1961-06-28 1963-08-09 Bolkow Entwicklungen Kg Articulation sans frottement
US3434899A (en) * 1961-11-06 1969-03-25 Bendix Corp Laminated coupling
US3228481A (en) * 1964-04-24 1966-01-11 Bendix Corp Tie bar bushing
US3249161A (en) * 1964-12-02 1966-05-03 Karl E Schoenherr Feathering controllable pitch propeller
US3470962A (en) * 1967-02-07 1969-10-07 Westland Aircraft Ltd Rotor heads for rotary wing aircraft
US3384185A (en) * 1967-06-02 1968-05-21 Aerojet General Co Rotor hubs

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3893788A (en) * 1973-02-06 1975-07-08 Bendix Corp Flexible coupling
US3879153A (en) * 1974-01-07 1975-04-22 Gerald L Breuner Attachment for rotor hub and pairs of blades
US4153390A (en) * 1976-08-25 1979-05-08 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschrankter Haftung Helicopter rotor structure
US4163630A (en) * 1976-08-25 1979-08-07 Messerschmitt-Bolkow-Blohm Gmbh Helicopter rotor structure
US4183718A (en) * 1976-12-11 1980-01-15 Messerschmitt-Bolkow-Blohm Gmbh Rotor for a rotary wing aircraft
US4299539A (en) * 1977-11-30 1981-11-10 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschraenkter Haftung Four-blade rotor, especially for helicopters
US4251188A (en) * 1977-12-17 1981-02-17 Messerschmitt-Boelkow-Blohm Gesellschaft Mit Beschraenkter Haftung Four-blade rotor, especially for helicopters
US4243359A (en) * 1978-01-18 1981-01-06 Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter Haftung Rotor structure, especially for hingeless rotary wing aircraft
US5110260A (en) * 1990-12-17 1992-05-05 United Technologies Corporation Articulated helicopter rotor within an improved blade-to-hub connection
US5474424A (en) * 1991-07-03 1995-12-12 Aerospatiale Societe Nationale Industrielle Rotorcraft rotor head, which is rigid in drag and articulated in pitch and flapping
WO2015183658A1 (en) * 2014-05-30 2015-12-03 Sikorsky Aircraft Corporation Structurally efficient pin wrap
US10549841B2 (en) 2014-05-30 2020-02-04 Sikorsky Aircraft Corporation Structurally efficient pin wrap
US10562608B1 (en) * 2017-05-25 2020-02-18 Amazon Technologies, Inc. Variable pitch mechanisms for propeller blades using linear actuation
US11021234B1 (en) 2017-05-25 2021-06-01 Amazon Technologies, Inc. Variable pitch mechanisms for propeller blades using a compound gearbox

Also Published As

Publication number Publication date
DE1531359B1 (de) 1969-09-11
FR1559400A (enrdf_load_stackoverflow) 1969-03-07
ES356058A1 (es) 1969-12-16
GB1196318A (en) 1970-06-24

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