US3972491A — Two-position helicopter main rotor

Claim 1

Independent Claim 150 words

A helicopter having: A. a fuselage, B. a main lift rotor including hub and blades, C. means to support said lift rotor in two positions of elevation about the helicopter fuselage including: 1. a first shaft supported to project upwardly from the helicopter fuselage and to be rotated about an axis of rotation, 2. a second shaft connected at its first end to the first shaft so that its second end is positioned in greater vertical elevation above the fuselage than said first shaft and so that said second shaft is driven in rotation about said axis of rotation by said first shaft, and 3. means connecting said rotor to said second shaft second end for rotation therewith about said axis of rotation and so that said rotor may be disconnected from said second shaft second end and lowered with the blades attached to be connected to said first shaft.

Claim 2

Dependent Claim 150 words

A helicopter having: A. a fuselage, B. a main lift rotor including hub and blades, C. means to support said lift rotor in two positions of elevation about the helicopter fuselage including: 1. a first shaft supported to project upwardly from the helicopter fuselage and to be rotated about an axis of rotation, 2. a second shaft connected at its first end to the first shaft so that its second end is positioned in greater vertical elevation above the fuselage than said first shaft and so that said second shaft is driven in rotation about said axis of rotation by said first shaft, and 3. means connecting said rotor to said second shaft second end for rotation therewith about said axis of rotation and so that said rotor may be disconnected from said second shaft second end and lowered with the blades attached to be connected to said first shaft.

Claim 3

Dependent Claim 70 words

A helicopter according to claim 1 wherein said second shaft is of substantially circular cross section and has a selected maximum diameter, and wherein said rotor hub has a central aperture of substantially circular cross section to permit it to be sleeved along the second shaft and shaped so that its minimum inner diameter is greater than the maximum diameter of the second shaft throughout the region of hub motion.

Claim 4

Dependent Claim 51 words

A helicopter according to claim 2 wherein said first shaft is a main rotor drive shaft, wherein said second shaft is an extension shaft, and including first means connecting said drive shaft to said extension shaft first end, and second means connecting said rotor hub to said extension shaft second end.

Claim 5

Dependent Claim 151 words

A helicopter according to claim 3 wherein said second connecting means includes: A. spline means connecting the outer diameter of the extension shaft second end to the inner diameter of the hub and extending along said axis of rotation so that the rotor hub may be moved with respect to the shaft extension along the axis of rotation, B. peripheral flange means extending from the outer end of said shaft extension to be juxtapositioned to the top surface of the hub, C. cooperating conical surfaces between said extension shaft outer diameter surface and said hub inner diameter surface adjacent the hub top surface shaped to define a lifting cone connection therebetween, D. means connecting said flange means to said hub top surface to establish a preloaded condition therebetween along said lifting cone connection, E. means supporting the lower side of the hub in preloaded condition from the extension shaft outer surface.

Claim 6

Dependent Claim 74 words

A helicopter according to claim 3 wherein said second connecting means includes: A. a circumferential lift flange projecting radially from the top of said extension shaft and having a top surface, and having a bottom surface juxtapositioned to the rotor hub top surface, B. rotor head moment reacting means connecting said lift flange to said rotor hub top surface, and C. rotor torque reacting means connecting said lift flange to said hub top surface.

Claim 7

Dependent Claim 76 words

A helicopter according to claim 5 wherein said rotor head moment reacting means constitutes a plurality of bolt members positioned circumferentially about the top surface of said lift flange and extending through apertures in said lift flange and threadably engaging threaded apertures in said hub, and wherein said rotor torque reacting means comprises at least one bolt member extending through said lift flange top surface and through aligned apertures in said lift flange and said hub.

Claim 8

Dependent Claim 28 words

A helicopter according to claim 6 and wherein said torque reacting bolt member is an expansion bolt having expansion washers extending between the bolt and the aligned apertures.

Claim 9

Dependent Claim 130 words

A helicopter according to claim 4 wherein said first connecting means includes: A. an axial spline connection between the inner diameter of the first end of the extension shaft and the outer diameter of the drive shaft, a conical interface between the drive shaft outer diameter surface and the extension shaft inner diameter surface at a position on the rotor side of the extension shaft from the axial spline connection, a mast nut threadably engaging the drive shaft at a station closer to the extension shaft second end than said conical interface, preload means acting on said mast nut to preload the drive shaft and the extension shaft along the conical interface, and means to support the extension shaft inner end from the drive shaft outer diameter in preloaded fashion.

Claim 10

Dependent Claim 73 words

A helicopter according to claim 8 wherein said means supporting the hub lower side from the extension shaft outer diameter and said means supporting the extension shaft inner end from the drive shaft outer diameter constitute: split ring cone shaped members matingly engaging corresponding surfaces on the extension shaft and hub and the extension shaft and drive shaft, respectively, a pressure plate member preloadable to preload the split cone members between said parts.

Claim 11

Dependent Claim 58 words

A helicopter according to claim 9 including means to support said drive shaft for rotation about an axis of rotation including: A. a transmission housing, B. a standpipe extending vertically from said transmission housing, and wherein said interconnection between said pressure plate member of said extension shaft-to-drive shaft connecting means is between said pressure plate and said standpipe.

Claim 12

Dependent Claim 72 words

A helicopter according to claim 10 and including a swashplate supported from said standpipe for motion therealong and tilting with respect thereto and including: A. a stationary portion, a rotatable portion, means connecting said rotatable portion to each of said blades to effect pitch change motion of said blades through swashplate motion, and scissors means connecting said swashplate rotatable portion to the pressure plate member of said extension shaft-to-drive shaft interconnecting means.

Claim 13

Dependent Claim 29 words

A helicopter according to claim 9 and including means to prevent rotation between the rotor hub and blades and the fuselage when the rotor is in its lowered position.

Claim 14

Dependent Claim 68 words

A helicopter according to claim 12 wherein said rotation preventing means includes: A. means interconnecting the pressure plate member of said extension shaft-to-drive shaft interconnecting means to the helicopter fuselage to prevent rotation therebetween when the rotor is in its lowered position, and B. means interconnecting both pressure plate members when the rotor is in its lowered condition to prevent rotation of the rotor with respect to fuselage.

Claim 15

Dependent Claim 41 words

A helicopter according to claim 9 and including means operatively connected to said pressure plate members and said split cone members so as to pull said cones out of engagement with their mating surfaces when the pressure plate member is withdrawn.

Claim 16

Dependent Claim 27 words

A helicopter according to claim 1 and including frictionless means to concentrically guide the motion of the hub over the extension shaft during the hub lowering operation.

Claim 17

Dependent Claim 30 words

A helicopter according to claim 1 and including: A. means to connect said hub to said first shaft when so lowered to prevent torsional motion and react head moments therebetween.

Claim 18

Dependent Claim 33 words

A helicopter according to claim 16 wherein the hub-to-first shaft connecting means includes at least one split cone member bearing against a corresponding conically shaped surface of the first shaft or the hub.

Claim 19

Dependent Claim 41 words

A helicopter according to claim 1 and including means to disconnect said rotor hub and blades from said second shaft second end and to lower said rotor with its blades attached so as to envelop the first shaft for connection thereto.

Claim 20

Dependent Claim 20 words

A helicopter according to claim 18 and including means to torsionally restrain said rotor hub and blades when being lowered.

Claim 21

Dependent Claim 22 words

A helicopter according to claim 19 and including means to connect said rotor to said first shaft when in its lower position.

Claim 22

Dependent Claim 29 words

A helicopter according to claim 1 and including means to prevent rotation between the rotor hub and blades and the fuselage when the rotor is in its lowered position.

Claim 23

Dependent Claim 68 words

A helicopter according to claim 21 wherein said rotation preventing means includes: A. means interconnecting the pressure plate member of said extension shaft-to-drive shaft connecting means to the helicopter fuselage to prevent rotation therebetween when the rotor is in its lowered position, and B. means connecting both pressure plate members when the rotor is in its lowered condition to prevent rotation of the rotor with respect to fuselage.

Claim 24

Independent Claim 139 words

The method of moving a helicopter rotor with the blades attached thereto from a flight position remote from the fuselage to a transport position in close proximity to the fuselage wherein the rotor hub is initially connected to an extension shaft projecting from and supported by the rotor drive shaft and wherein the rotor hub is connected to the drive shaft in the transport position including the steps of: A. disconnecting the rotor hub from the shaft extension, B. controllably lowering the rotor hub with the blades attached thereto from said flight position to said transport position, removing said extension shaft from said drive shaft, and connecting said rotor hub to said drive shaft when in said transport position so as to prevent rotation of the hub and blades about the drive shaft and with respect to the fuselage.

Claim 25

Independent Claim 139 words

The method of moving a helicopter rotor with the blades attached thereto from a flight position remote from the fuselage to a transport position in close proximity to the fuselage wherein the rotor hub is initially connected to an extension shaft projecting from and supported by the rotor drive shaft and wherein the rotor hub is connected to the drive shaft in the transport position including the steps of: A. disconnecting the rotor hub from the shaft extension, B. controllably lowering the rotor hub with the blades attached thereto from said flight position to said transport position, removing said extension shaft from said drive shaft, and connecting said rotor hub to said drive shaft when in said transport position so as to prevent rotation of the hub and blades about the drive shaft and with respect to the fuselage.

Claim 26

Dependent Claim 23 words

The method according to claim 23 wherein said last step includes the step of anchoring the rotor hub to the fuselage against rotation.

Claim 27

Dependent Claim 36 words

The method according to claim 24 and including the additional step of connecting the blades to the fuselage when the rotor is in the transport position so that blade pitch may be controlled from the fuselage.

Claim 28

Dependent Claim 20 words

A method according to claim 25 wherein the last named step comprises connecting the helicopter blades to the rotor swashplate.

Claim 29

Dependent Claim 26 words

A method according to claim 26 and including the step of folding the rotor blades with respect to the rotor hub for improved stowability or transportability.

Claim 30

Dependent Claim 30 words

The method according to claim 26 including the additional step of supporting the blades in fixed relation to the hub to prevent pitch change variation during the rotor retraction procedure.

Claim 31

Dependent Claim 33 words

The method according to claim 23 wherein said rotor hub and blades are lowered from said flight to said transport position while being restrained from rotational motion with respect to the extension shaft.

Claim 32

Independent Claim 100 words

The method of moving a helicopter main lift rotor from a first elevated position above the fuselage wherein the rotor is supported from an extension shaft projecting from a first shaft to a second elevated position above the fuselage wherein the rotor is supported from the first shaft comprising the steps of disconnecting the helicopter rotor from the extension shaft, securing the helicopter blades in fixed position with respect to the rotor hub, lowering the rotor with the blade so secured to the elevation of the first shaft, removing the extension shaft, and connecting the rotor to the first shaft.

Claim 33

Independent Claim 100 words

The method of moving a helicopter main lift rotor from a first elevated position above the fuselage wherein the rotor is supported from an extension shaft projecting from a first shaft to a second elevated position above the fuselage wherein the rotor is supported from the first shaft comprising the steps of disconnecting the helicopter rotor from the extension shaft, securing the helicopter blades in fixed position with respect to the rotor hub, lowering the rotor with the blade so secured to the elevation of the first shaft, removing the extension shaft, and connecting the rotor to the first shaft.

Claim 34

Independent Claim 102 words

The method of moving a helicopter main lift rotor from a first elevated position above the fuselage wherein the rotor is supported from an extension shaft projecting from a first shaft to a second elevated position above the fuselage wherein the rotor is supported from the first shaft comprising the steps of disconnecting the helicopter rotor from the extension shaft, lowering the rotor with the blade secured to the elevation of the first shaft while restraining the rotor from rotating with respect to the extension shaft during the lowering operation, removing the extension shaft, and connecting the rotor to the first shaft.

Claim 35

Independent Claim 102 words

The method of moving a helicopter main lift rotor from a first elevated position above the fuselage wherein the rotor is supported from an extension shaft projecting from a first shaft to a second elevated position above the fuselage wherein the rotor is supported from the first shaft comprising the steps of disconnecting the helicopter rotor from the extension shaft, lowering the rotor with the blade secured to the elevation of the first shaft while restraining the rotor from rotating with respect to the extension shaft during the lowering operation, removing the extension shaft, and connecting the rotor to the first shaft.

Claim 36

Dependent Claim 225 words

A tool adapted for use with a helicopter having a two-position rotor and adapted to be connected to and driven by an extension shaft member which extends substantially vertically from, is connected to and is driven by a main rotor drive shaft member, said tool having: A. a fixed portion adapted to be connected to and supported from said main drive shaft, B. a movable portion including: 1. a frame portion movably supported from said fixed portion for motion along the rotor axis of rotation, 2. means adapted to connect said frame portion to the helicopter rotor hub, 3. means to cause the tool movable portion to move with respect to the tool fixed portion when so connected to the rotor hub and blades so as to cause the rotor hub with blades to be lowered from its elevated position in attachment with the shaft extension to a position of equal elevation with the main drive shaft so as to envelop the drive shaft for connection thereto, 4. means to torsionally restrain said hub and blades from rotating during the hub and blades lowering operation, 5. means to attach said movable portion to said shaft extension, and 6. means to cause said movable portion so connected to said shaft extension to move in the opposite direction and remove said shaft extension from said drive shaft.

Claim 37

Dependent Claim 225 words

A tool adapted for use with a helicopter having a two-position rotor and adapted to be connected to and driven by an extension shaft member which extends substantially vertically from, is connected to and is driven by a main rotor drive shaft member, said tool having: A. a fixed portion adapted to be connected to and supported from said main drive shaft, B. a movable portion including: 1. a frame portion movably supported from said fixed portion for motion along the rotor axis of rotation, 2. means adapted to connect said frame portion to the helicopter rotor hub, 3. means to cause the tool movable portion to move with respect to the tool fixed portion when so connected to the rotor hub and blades so as to cause the rotor hub with blades to be lowered from its elevated position in attachment with the shaft extension to a position of equal elevation with the main drive shaft so as to envelop the drive shaft for connection thereto, 4. means to torsionally restrain said hub and blades from rotating during the hub and blades lowering operation, 5. means to attach said movable portion to said shaft extension, and 6. means to cause said movable portion so connected to said shaft extension to move in the opposite direction and remove said shaft extension from said drive shaft.

Claim 38

Dependent Claim 49 words

A tool according to claim 32 and including arm members connected to and projecting outwardly from said frame portion, means supported by said arm members and adapted to be connected to the helicopter rotor blades so as to restrain the blades in fixed relation with respect to the hub.

Claim 39

Dependent Claim 27 words

A tool according to claim 33 wherein said means adapted to be connected to said blades are connected to said arm members through a ball joint connection.

Claim 40

Dependent Claim 40 words

A tool according to claim 34 wherein said means to connect said frame portion to the rotor hub constitutes a plurality of bolts adapted to extend through the frame portion and the rotor hub so as to connect the two.

Claim 41

Dependent Claim 32 words

A tool according to claim 35 wherein said means to cause said movable portion of the tool to move relative to the fixed portion of the tool is a power piston-cylinder mechanism.

Claim 42

Dependent Claim 54 words

A tool according to claim 33 wherein said means to connect the helicopter rotor blades to the hub are constructed to be detachable from the arm members when the helicopter hub and blades are in their lowered position enveloping the drive shaft and to then be connected to the conventional helicopter pitch control system.

Claim 43

Dependent Claim 26 words

A tool according to claim 37 wherein said frame portion includes access holes to permit access to the rotor interior portions during the rotor moving operation.

Claim 44

Dependent Claim 31 words

A tool according to claim 38 shaped so that its fixed portions is piloted in the drive shaft member and so that its movable portion is piloted on the rotor hub.

Claim 45

Dependent Claim 27 words

A tool according to claim 32 wherein said torsional restraint means comprises cooperating tongue and groove members extending between said frame portion and the extension shaft member.

Claim 46

Dependent Claim 37 words

A tool according to claim 32 wherein said torsional restraint means comprise one or more anti-torque rods adapted to be anchored to the fuselage and extend through said frame portion and the hub or hub connected parts.

Claim 47

Dependent Claim 40 words

A tool according to claim 32 wherein said means to connect said frame portion to rotor hub constitute one or more cable members hanging from the frame member and adapted to be connected to and support the rotor hub therefrom.

Claim 48

Dependent Claim 32 words

A tool according to claim 42 wherein said means to cause said movable portion of the tool to move relative to the fixed portion of the tool is a jack screw mechanism.

Claim 49

Dependent Claim 30 words

A tool according to claim 43 shaped so that its fixed portion is piloted in the drive shaft and so that its movable portion is piloted on the rotor hub.

Claim 50

Dependent Claim 91 words

A helicopter having a rotor retractable from an elevated position to a retracted position including: A. a helicopter fuselage, B. a rotor drive shaft projecting from said helicopter fuselage and supported therefrom for rotation about an axis of rotation, C. an extension shaft projecting vertically above said drive shaft and connected at its first end thereto to be drivingly rotated thereby about said axis of rotation and so that its second end is in a position farther removed from said fuselage than is said drive shaft, D. a helicopter rotor including:

Claim 51

Dependent Claim 91 words

A helicopter having a rotor retractable from an elevated position to a retracted position including: A. a helicopter fuselage, B. a rotor drive shaft projecting from said helicopter fuselage and supported therefrom for rotation about an axis of rotation, C. an extension shaft projecting vertically above said drive shaft and connected at its first end thereto to be drivingly rotated thereby about said axis of rotation and so that its second end is in a position farther removed from said fuselage than is said drive shaft, D. a helicopter rotor including:

Claim 52

Dependent Claim 58 words

a hub connected to the second end of said extension shaft in said elevated position, 2. a plurality of blades extending substantially radially from said hub and supported therefrom for pitch change motion, E. means to move said rotor between said elevated position and a retracted position wherein said rotor hub envelops said drive shaft for connection thereto.

Claim 53

Dependent Claim 58 words

a hub connected to the second end of said extension shaft in said elevated position, 2. a plurality of blades extending substantially radially from said hub and supported therefrom for pitch change motion, E. means to move said rotor between said elevated position and a retracted position wherein said rotor hub envelops said drive shaft for connection thereto.

Claim 54

Dependent Claim 187 words

A helicopter according to claim 45 wherein said rotor moving means includes: A. a stationary portion adapted to be connected to and supported from said drive shaft, and B. a movable portion connected to said stationary portion and adapted to be movable with respect thereto along said axis of rotation and including: 1. a frame member operably connected to said hub, 2. arm members projecting substantially radially from said frame member and connected thereto, 3. means to connect said blades to said arm members so as to prevent pitch change motion of said blades with respect to said hub during the rotor moving process, 4. means to cause said movable portion to move with respect to said fixed portion along said axis of rotation to thereby lower said rotor hub and blades once disconnected from said extension shaft to said retracted position, 5. means to connect said movable portion so lowered to said extension shaft, and 6. means to cause said movable portion to move with respect to said fixed portion in the opposite direction and carry said shaft extension out of contact with said drive shaft.

Claim 55

Dependent Claim 25 words

A helicopter according to claim 46 including means to connect the helicopter hub with blades attached thereto to the fuselage when in said retracted position.

Claim 56

Dependent Claim 33 words

A helicopter according to claim 45 and including first means connecting said drive shaft to said extension shaft first end, and second means connecting said rotor hub to said extension shaft second end.

Claim 57

Dependent Claim 152 words

A helicopter according to claim 40 wherein said second connecting means includes: A. spline means connecting the outer diameter of the extension shaft second end to the inner diameter of the hub and extending along said axis of rotation so that the rotor hub may be moved with respect to the extension shaft along the axis of rotation, B. peripheral flange means extending from the outer end of said shaft extension to be juxtapositioned to the top surface of the hub, C. cooperating conical surfaces between said extension shaft outer diameter surface and said hub inner diameter surface adjacent the hub top surface shaped to define a lifting cone connection therebetween, D. means connecting said flange means to said hub top surface to establish a preloaded condition therebetween along said lifting cone connection, and E. means supporting the lower side of the hub in preloaded condition from the extension shaft outer surface.

Claim 58

Dependent Claim 130 words

A helicopter according to claim 49 wherein said first connecting means includes: A. an axial spline connection between the inner diameter of the first end of the extension shaft and the outer diameter of the drive shaft, a conical interface between the drive shaft outer diameter surface and the extension shaft inner diameter surface at a position on the rotor side of the extension shaft from the axial spline connection, a mast nut threadably engaging the drive shaft at a station closer to the extension shaft second end than said conical interface, preload means acting on said mast nut to preload the drive shaft and the extension shaft along the conical interface, and means to support the extension shaft inner end from the drive shaft outer surface in preloaded fashion.

Claim 59

Dependent Claim 73 words

A helicopter according to claim 50 wherein said means supporting the hub lower side from the extension shaft outer surface and said means supporting the extension shaft inner end from the drive shaft outer surface constitute: split ring cone shaped members matingly engaging corresponding surfaces on the extension shaft and hub and the extension shaft and drive shaft, respectively, a pressure plate member preloadable to preload the split cone members between said parts.

Claim 60

Dependent Claim 142 words

A helicopter according to claim 45 wherein said rotor moving means includes: A. a fixed portion adapted to be connected to and supported from said main drive shaft, B. a movable portion including: 1. a frame portion movably supported from said fixed portion for motion along the rotor axis of rotation, 2. means adapted to connected said frame portion to the helicopter rotor hub, 3. means to cause the tool movable portion to move with respect to the tool fixed portion when so connected to the rotor hub and blades so as to cause the rotor hub with blades connected thereto to be lowered from its elevated position in attachment with the shaft extension to a position enveloping the drive shaft for connection thereto, 4. means to torsionally restrain said hub and blades from rotating during the hub and blades lowering operation,

Claim 61

Dependent Claim 39 words

means to attach said movable portion to said shaft extension, and 6. means to cause said movable portion so connected to said shaft extension to move in the opposite direction and remove said shaft extension from said drive shaft.

Claim 62

Dependent Claim 39 words

means to attach said movable portion to said shaft extension, and 6. means to cause said movable portion so connected to said shaft extension to move in the opposite direction and remove said shaft extension from said drive shaft.

Claim 63

Dependent Claim 49 words

A helicopter according to claim 52 and including arm members connected to and projecting outwardly from said frame portion, means supported by said arm members and adapted to be connected to the helicopter rotor blades so as to restrain the blades in fixed relation with respect to the hub.

Claim 64

Dependent Claim 27 words

A helicopter according to claim 53 wherein said means adapted to be connected to said blades are connected to said arm members through a ball joint connection.

Claim 65

Dependent Claim 40 words

A helicopter according to claim 54 wherein said means to connect said frame portion to the rotor hub constitutes a plurality of bolts adapted to extend through the frame portion and the rotor hub so as to connect the two.

Claim 66

Dependent Claim 32 words

A helicopter according to claim 55 wherein said means to cause said movable portion of the tool to move relative to the fixed portion of the tool is a power piston-cylinder mechanism.

Claim 67

Dependent Claim 54 words

A helicopter according to claim 56 wherein said means to connect the helicopter rotor blades to the hub are constructed to be detachable from the arm members when the helicopter hub and blades are in their lowered position enveloping the drive shaft and to then be connected to the conventional helicopter pitch control system.

Claim 68

Dependent Claim 26 words

A helicopter according to claim 57 wherein said frame portion includes access holes to permit access to the rotor interior portions during the rotor moving operation.

Claim 69

Dependent Claim 37 words

A helicopter according to claim 58 wherein said rotor moving means is shaped so that its fixed portion is piloted in the drive shaft member and so that its movable portion is piloted on the rotor hub.

Claim 70

Dependent Claim 27 words

A helicopter according to claim 59 wherein said torsional restraint means comprises cooperating tongue and groove members extending between said frame portion and said extension shaft member.

Claim 71

Dependent Claim 37 words

A helicopter according to claim 60 wherein said torsional restraint means comprise one or more anti-torque rods adapted to be anchored to the fuselage and extend through said frame portion and the hub or hub connected parts.

Claim 72

Dependent Claim 40 words

A helicopter according to claim 61 wherein said means to connect said frame portion to rotor hub constitute one or more cable members hanging from the frame member and adapted to be connected to and support the rotor hub therefrom.

Claim 73

Dependent Claim 31 words

A helicopter according to claim 62 wherein said means to cause said movable portion of the tool to move relative to the fixed portion of the tool is a jack-screw mechanism.

Claim 74

Dependent Claim 37 words

A helicopter according to claim 63 wherein said rotor moving means is shaped so that its fixed portion is piloted in the drive shaft member and so that its movable portion is piloted from the rotor hub.

Claim 75

Dependent Claim 41 words

A helicopter according to claim 51 and including means operatively connected to said pressure plate members and said split cone members so as to pull said cones out of engagement with their mating surfaces when the pressure plate member is withdrawn.

Claim 76

Dependent Claim 41 words

A helicopter according to claim 46 and including frictionless means to concentrically guide the motion of the hub over the extension shaft and of the extension shaft over the drive shaft during the hub lowering and the extension shaft removal operation.

Claim 77

Independent Claim 116 words

The method of retracting a helicopter rotor main rotor with blades attached thereto from an extended position to a retracted position wherein the helicopter is initially connected to an extension shaft extending substantially vertically from and drivingly connected to the main rotor drive shaft including the steps of: A. disconnecting the rotor hub from the extension shaft while supporting it in its elevated position, B. controllably lowering the rotor hub with the blades so attached thereto from its extended position to a position enveloping the rotor drive shaft so that the rotor does not rotate about the shafts during the rotor lowering procedure, and C. connecting the rotor hub so lowered to the rotor drive shaft.

Claim 78

Independent Claim 116 words

The method of retracting a helicopter rotor main rotor with blades attached thereto from an extended position to a retracted position wherein the helicopter is initially connected to an extension shaft extending substantially vertically from and drivingly connected to the main rotor drive shaft including the steps of: A. disconnecting the rotor hub from the extension shaft while supporting it in its elevated position, B. controllably lowering the rotor hub with the blades so attached thereto from its extended position to a position enveloping the rotor drive shaft so that the rotor does not rotate about the shafts during the rotor lowering procedure, and C. connecting the rotor hub so lowered to the rotor drive shaft.

Claim 79

Dependent Claim 30 words

The method according to claim 67 and including the additional step of connecting the rotor blades to the helicopter after the rotor is lowered to control pitch change motion thereof.

Claim 80

Dependent Claim 21 words

The method according to claim 68 and including the additional step of folding the blades with respect to the rotor hub.

Claim 81

Dependent Claim 28 words

The method according to claim 67 and including the additional step of removing the extension shaft after rotor lowering before connecting the rotor hub to the drive shaft.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1979-08-03	1980-02-02	1980-08-03	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1983-08-03	1984-02-02	1984-08-03	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1987-08-03	1988-02-02	1988-08-03	$7700.00	Window Closed / Lapsed

Two-position helicopter main rotor

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag