US3743441A - Helicopter blade folding and locking mechanism - Google Patents

Helicopter blade folding and locking mechanism Download PDF

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Publication number
US3743441A
US3743441A US00194881A US3743441DA US3743441A US 3743441 A US3743441 A US 3743441A US 00194881 A US00194881 A US 00194881A US 3743441D A US3743441D A US 3743441DA US 3743441 A US3743441 A US 3743441A
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United States
Prior art keywords
blade
hub
link
links
piston
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Expired - Lifetime
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US00194881A
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English (en)
Inventor
D Ferris
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Raytheon Technologies Corp
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United Aircraft Corp
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C27/00—Rotorcraft; Rotors peculiar thereto
    • B64C27/32—Rotors
    • B64C27/46—Blades
    • B64C27/473—Constructional features
    • B64C27/50—Blades foldable to facilitate stowage of aircraft

Definitions

  • ABSTRACT A power piston actuates a series of link members which (gill. are pivotany interconnected and which are also pivot [58] Fi d 6/1 42 l ally connected to the rotor hub and the blade so that e o 2 /7 actuation of the power piston will actuate said links to cause said blade to move to its folded position and to References Cited be locked in the folded position due to a link over- UNITED STATES PATENTS Vacca et a] 416/142 center condition.
  • blade fold mechanisms use complicated series of links and cams, most of which are located externally of the blade and hub and are therefore vulnerable to breakage in use and by firearms, corrosion damage besides being complicated in nature and are aerodynamically unsound.
  • a primary object of this invention is to provide an improved blade fold and lock mechanism in which the blade is both folded and locked by a simple link mecha' nism.
  • the entire blade folding and locking mechanism is located internally within the blade or hub so that it is protected thereby from damage due to external forces.
  • the links are of a selected length and orientation to fit the fold angle and over-center requirements, and best provide, within the limits of practicality, a maximum folding moment about the fold pin at the points of maximum blade resistance to folding and unfolding of the blades.
  • apparatus is provided to control the degree of folding of the blade and to positively stop the power piston when the blade is in its fully folded condition.
  • the folding links go into over-center-relationship when the blade is in its fullyfolded position and so remain when hydraulic power is removed from the power piston.
  • the blade is folded about a fold pin having an axis forming a selected angle with the blade feathering axis and with the blade plane of rotation so as to safely and selectively control the path of the blade during the folding operation and to selectively position the blade in the desired fully folded position, while maintaining adequate clearance from the ground, fuselage, and other blades during the folding operation.
  • FIG. 1 is a plan view of my blade folding and lock mechanism in its rotor head environment, partially broken away to reveal the folding and locking mechanism in the blade operating or unfolded position.
  • FIG. 2 is a side view of my blade fold mechanism in the blade operative or unfolded position, partially in cross section.
  • FIG. 3 is a plan view of my blade fold mechanism in the blade folded position.
  • FIG. 4 is a schematic representation of the blade fold pin and its axis with respect to the blade feathering axis and the rotor plane of rotation.
  • FIG. 5 is a graphic representation of blade fold motion for three selected conditions.
  • FIG. 6 is a partial showing of my invention in a second type of rotor head.
  • helicopter rotor 10 comprises rotor hub 12 which is mounted for rotation about axis of rotation 14 and helicopter blade 16, which is one of a series of identical blades projecting from hub 12 for rotation therewith about axis 14 so as to create lift.
  • Blades 16 are mounted from hub 12 so as to be rotatable about feathering axis 18 through the action of pitch change horn 20, which is controlled by conventional pitch change control mechanism (not shown).
  • Blade 16 is connected to hub 12 through fold hinge 15 and through sleeve 22, which generally envelops the blade fold and lock mechanism 30.
  • There is one such mechanism 30 for each blade of different fold angle and both the blades and their blade fold and lock mechanism which may be identical, but not necessarily so due to different clearance problems around the aircraft.
  • Blade 16 is pivotally connected to fold hinge 15 through fold pin 17 to permit blade folding and to sleeve 22 and hence hub 14.
  • the axis 19 of fold pin 17 forms a selected angle with respect to both the plane of the blade feathering axis 18 and the rotor plane of rotation 21 so as to permit the blade tofollow a selected path during the folding and unfolding motion and to assume a selected position when fully folded so as to avoid all obstacles, including the ground, the fuselage, and other blades, during the folding and unfolding motion and so as to nest selectively with the otherblades, fuselage, or the like when in the fully folded position
  • the significance of the compound angle of axis 19 of fold pin 17 depicted in FIG. 4 is best understood by viewing FIG.
  • Line 51 represents the blade operational or zero degree fold positions and line 53 represents the blade fully folded position.
  • Line 55 represents the path of a blade when blade folding axis 19 does not form an angle to the feathering axis plane or the rotor plane. The result of blade fold motion along line 55 would be interference between the various blades during the blade folding and unfolding operation.
  • Line 57 represents the path when a blade which has selected angular relationship with the blade feathering axis plane only and not with'the plane of the rotor. While blades following path 57 would not interfere with one another, the maximum downward vertical displacement of the blade, which would be encountered at the blade 90 fold angle, would exceed the minimum required ground clearance and therefore the blade would possibly strike the ground during blade folding and unfolding operation.
  • Line 59 is the path of blade fold when the angular relationship shown in FIG. 4 exists between the blade fold pin axis and both the rotor planeand the feathering axis plane. It will be noted that blade path 59 provides increased ground clearance during the blade folding and unfolding operations and therefore avoids the blade striking the ground, however, the final vertical blade displacement is the same, and therefore the blade fully folded nesting position is the same for blade paths 57 and 59.
  • FIGS. 1-3 illustrate my blade fold and lock mechanism 30 in the environment of a particular rotor head
  • my blade fold and lock mechanism 30 is also usable with a conventional sleeve and spindle rotor head of the type shown in US. Pat. No. 3,097,701, wherein the piston and crank or link mechanism would be mounted within the spindle and rotation between the spindle and sleeve would be taken out by a selfaligning hearing at 52.
  • blade fold and lock mechanism 30 includes linkage assembly 32, which is powered by power cylinder-piston arrangement 34, which includes piston member 36 positioned within cylinder 38 and with provisions for either air or hydraulic fluid to be directed thereinto either through port 40 or port 42 to actuate linkage mechanism 32.
  • power cylinder-piston arrangement 34 which includes piston member 36 positioned within cylinder 38 and with provisions for either air or hydraulic fluid to be directed thereinto either through port 40 or port 42 to actuate linkage mechanism 32.
  • piston 36 moves leftwardly to move linkage mechanism 32 to its blade fold position and, when actuating fluid enters chamber 46 through port 40, it moves piston 36 to the right, to unfold the blade 16 and return it to its normal operation position.
  • Spacer 48 is positioned in cylinder 38 and is of selected width W to serve as a positive stop for piston 36 when the blades are in their fully folded position. Spacers of selected width W may be used to vary piston 36 stroke.
  • Piston rod 50 connects through spherical clevis joint 52 to one end of link member 54, while the other end of link 54 connects through spherical clevis joint 56 to one of the three corners of triangular link 58.
  • a second corner of triangular link 58 is pivotally connected at pivot joint 60 to sleeve 22.
  • Link 58 is connected at its third corner at pivot joint 62 to twin link members 64, which are pivotally connected at their other ends at pivot connection 66 to fold bracket 70, which is, in turn, connected to fold hinge 15 through bolt members 73.
  • the joints 66, 62 and 60 form a triangle when the blade is in its operative, nonfolded position with the interconnected pivot joint 62 closest to hub 12, and with one corner 60 of the triangle connected to the hub, while the other corner 66 of the triangle is connected to the fold bracket 70 in turn to fold hinge l and to blade 16.
  • flanges 72 of sleeve 22 engage flanges 74 of fold hinge so that a single lock pin 76 can pass through aligned apertures in these flanges to lock blade 16 and fold hinge 15 in its unfolded or operable FIGS. 1 and 2 position.
  • Pin 76 can be withdrawn from inner flanges of 72-74 by any conventional mechanism such as conventional solenoid 79 to permit blade folding. This is the first step in the blade folding operation. Thereafter, actuating fluid is caused to enter chamber 44 to move piston 36 leftwardly and thereby cause piston rod 50 to move link 54 leftwardly. As best shown in FIG.
  • Over-center spring 92 which extends between fold bracket and link 58 serves to retain links 58 and 64 in their over-centered, locked position. Over-centering the links tends to put a tension load on piston 36, reacted by spacer 48 when blade wind forces is in the unfold direction. Fold links 58 and 64 move from the over-center condition to a straight line condition when blade wind force is in a fold direction. This provides tension on links 64 and 50. Spring 92, being preloaded in tension, tends to return blade to its overcenter condition when wind force in fold direction slackens.
  • links 58 and 64 coact, when powered by power piston 34, to both fold and lock blade 16 in its folded position with respect to hub 12.
  • Link 58 is made triangular in shape so that the most effective moment arms of point 86 about axis 60, and
  • point 82 about axis may be achieved to overcome the blade folding loads in their most severe fold angle condition.
  • the added advantage is in providing a smaller stroke of piston 36, reducing the required length of the sleeve, and reducing packaging requirements.
  • Shim 94 of selected thickness, may be positioned between fold bracket 70 and the remainder of blade 16 so as to selectively control or adjust the final angle to which link mechanism 32 causes blade 16 to fold with respect to hub 12.
  • a helicopter rotor having:
  • C. means to fold said blade with respect to said hub and to lock said blade in a folded position includ- 1.
  • two pivotally connected links of selected length and orientation so that the link free ends form a triangle with their interconnected ends so oriented that their interconnected ends are on the hub side of a line passing between the link free ends,
  • a helicopter rotor according to claim 2 and including means to control the stroke of said piston and hence the angle of folding of said blade.
  • a rotor according to claim 1 wherein said blade is pivotally connected to said hub by means of a blade fold pin whose axis is selectively oriented so as to form a preselected angle in relation to the blade feathering axis to control the path of folded'motion of the blade in its finally fully folded position and which also forms a selected angle relative to the rotor plane of rotation to provide adequate ground clearance for the blade during the folding motion.
  • a rotor according to claim 6 wherein the distance between the lines of force between said power means and said link pivot connections to said hub and said blade increase as the blade is so powered to a folded position so as to create maximum moments at the location of maximum blade resistance to folding.
  • one of said links is substantially triangular in shape with one corner thereof pivotally connected to the other link, with a second corner thereof pivotally connected to the hub or blade and with the third corner thereof pivotally connected to the power means.
  • a rotor according to claim 2 including means to control the stroke of said piston, and means to vary the angle of blade fold for the controlled piston stroke.
  • a helicopter rotor including:
  • blade folding and locking mechanism including:
  • said third link will cause the pivot interconnection between said first and second links to move into alignment with the pivot interconnection between said first link and said hub and said second link and said blade so as to cause the blade to fold with respect to the hub to a position beyond its normal fully folded position, and then to cause said pivotal interconnection between said first and second links to move to a positiontherebeyond to establish an overfor a piston stroke so controlled.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Chairs For Special Purposes, Such As Reclining Chairs (AREA)
  • Pivots And Pivotal Connections (AREA)
  • Transmission Devices (AREA)
US00194881A 1971-11-02 1971-11-02 Helicopter blade folding and locking mechanism Expired - Lifetime US3743441A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US19488171A 1971-11-02 1971-11-02

Publications (1)

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US3743441A true US3743441A (en) 1973-07-03

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US00194881A Expired - Lifetime US3743441A (en) 1971-11-02 1971-11-02 Helicopter blade folding and locking mechanism

Country Status (7)

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US (1) US3743441A (de)
JP (1) JPS4857398A (de)
CA (1) CA959812A (de)
DE (1) DE2253026C2 (de)
FR (1) FR2158542B1 (de)
GB (1) GB1368162A (de)
IT (1) IT970146B (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2631151A1 (de) * 1976-07-10 1978-01-12 Hans Leistner Verschwenkbare tragfluegel
US5211538A (en) * 1991-11-27 1993-05-18 Bell Helicopter Textron Inc. Method for folding helicopter main rotor blades
US6126398A (en) * 1998-05-28 2000-10-03 Eurocopter Deutschland Gmbh Two-piece rotor blade for a bearingless rotor of a helicopter
US6176679B1 (en) 1997-01-17 2001-01-23 Eurocopter Rotor with folding blades, for the rotary wings of an aircraft
US6783327B1 (en) 2002-12-12 2004-08-31 Davis Aircraft Products Co., Inc. Helicopter blade folding with blade droop
US7857590B1 (en) * 2006-08-11 2010-12-28 Neal Larry R Folding rotor for a rotorcraft
WO2016053410A3 (en) * 2014-08-21 2016-05-06 Sikorsky Aircraft Corporation System for shimming blade fold angle about an axis of rotation
US20170121018A1 (en) * 2014-05-02 2017-05-04 Sikorsky Aircraft Corporation Light weight rigid rotor with blade fold capability
CN107128478A (zh) * 2017-05-23 2017-09-05 安徽中科中涣防务装备技术有限公司 一种折叠机翼的快速展开装置
US10239605B2 (en) * 2016-09-19 2019-03-26 Bell Helicopter Textron Inc. Chordwise folding and locking of rotor systems

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010141132A2 (en) 2009-04-28 2010-12-09 Sikorsky Aircraft Corporation Proximity sensor valve and lock system using same

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3343610A (en) * 1965-06-29 1967-09-26 Vacca Luigi Mechanical blade locks
US3356155A (en) * 1965-07-29 1967-12-05 Donald L Ferris Blade fold adjustment and lock
US3369611A (en) * 1967-04-27 1968-02-20 Navy Usa Pitch mechanism lock for main helicopter rotor blade
US3438446A (en) * 1967-10-03 1969-04-15 United Aircraft Corp Rotor blade pitch lock

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3484175A (en) * 1967-10-12 1969-12-16 United Aircraft Corp Means and method of synchronously folding helicopter blades

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3343610A (en) * 1965-06-29 1967-09-26 Vacca Luigi Mechanical blade locks
US3356155A (en) * 1965-07-29 1967-12-05 Donald L Ferris Blade fold adjustment and lock
US3369611A (en) * 1967-04-27 1968-02-20 Navy Usa Pitch mechanism lock for main helicopter rotor blade
US3438446A (en) * 1967-10-03 1969-04-15 United Aircraft Corp Rotor blade pitch lock

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2631151A1 (de) * 1976-07-10 1978-01-12 Hans Leistner Verschwenkbare tragfluegel
US5211538A (en) * 1991-11-27 1993-05-18 Bell Helicopter Textron Inc. Method for folding helicopter main rotor blades
US6176679B1 (en) 1997-01-17 2001-01-23 Eurocopter Rotor with folding blades, for the rotary wings of an aircraft
US6126398A (en) * 1998-05-28 2000-10-03 Eurocopter Deutschland Gmbh Two-piece rotor blade for a bearingless rotor of a helicopter
US6783327B1 (en) 2002-12-12 2004-08-31 Davis Aircraft Products Co., Inc. Helicopter blade folding with blade droop
US7857590B1 (en) * 2006-08-11 2010-12-28 Neal Larry R Folding rotor for a rotorcraft
US10611471B2 (en) * 2014-05-02 2020-04-07 Sikorsky Aircraft Corporation Light weight rigid rotor with blade fold capability
US20170121018A1 (en) * 2014-05-02 2017-05-04 Sikorsky Aircraft Corporation Light weight rigid rotor with blade fold capability
WO2016053410A3 (en) * 2014-08-21 2016-05-06 Sikorsky Aircraft Corporation System for shimming blade fold angle about an axis of rotation
US10301015B2 (en) * 2014-08-21 2019-05-28 Sikorsky Aircraft Corporation System for shimming blade fold angle about an axis of rotation
US10239605B2 (en) * 2016-09-19 2019-03-26 Bell Helicopter Textron Inc. Chordwise folding and locking of rotor systems
CN107128478A (zh) * 2017-05-23 2017-09-05 安徽中科中涣防务装备技术有限公司 一种折叠机翼的快速展开装置
CN107128478B (zh) * 2017-05-23 2023-08-04 安徽中科中涣智能装备股份有限公司 一种折叠机翼的快速展开装置

Also Published As

Publication number Publication date
JPS4857398A (de) 1973-08-11
CA959812A (en) 1974-12-24
DE2253026C2 (de) 1982-04-08
DE2253026A1 (de) 1973-05-03
FR2158542A1 (de) 1973-06-15
FR2158542B1 (de) 1976-10-29
GB1368162A (en) 1974-09-25
IT970146B (it) 1974-04-10

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