US3589831A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for rotary wing vehicle
Assignee: Kaman Corp
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Filing: 1969-11-10
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Granted: 1971-06-29
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Expires: 1989-11-10
Abstract
Abstract A control system for a helicopter rotor has dual pitch changing mechanisms, one such mechanism for the inboard ends of the blades, and a second for servo flap control of an outboard station of each blade. Conventional cyclic and collective controls are provided in the vehicle, and the dual mechanisms operate in unison at moderate forward speeds, but function differentially at higher speeds to cyclically twist the rotor blades according to a predetermined airspeed schedule so that the advancing and retreating blades are cyclically twisted to reduce and to increase, respectively, the built-in negative twist of the torsionally resilient rotor blades.
Inventors
- 👤 Andrew Z Lemnios
- 👤 Richard W Hartswick
- 👤 Richard H Hollrock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:29
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/54; B64C27/72; B64C27/58; B64C27/59; Y; Y02; Y02T; Y02T50/00; Y02T50/30
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
122 words
In a rotary wing vehicle having cyclic and collective pitch controls, the improvement comprising a rotor hub having at least one generally radially extending blade, said blade having a built-in negative twist geometry, first means for cyclically and collectively changing the pitch of an inboard section of the blade in response to control inputs, second means for cyclically and collectively changing the pitch of an outboard section of the blade in response to control inputs, and means responsive to the forward speed of the vehicle for cyclically and collectively adjusting the input to at least one of said pitch-changing means with respect to the other to reduce the negative built-in twist while the blade is advancing during forward flight of the vehicle.
Claim 2
Dependent Claim
122 words
In a rotary wing vehicle having cyclic and collective pitch controls, the improvement comprising a rotor hub having at least one generally radially extending blade, said blade having a built-in negative twist geometry, first means for cyclically and collectively changing the pitch of an inboard section of the blade in response to control inputs, second means for cyclically and collectively changing the pitch of an outboard section of the blade in response to control inputs, and means responsive to the forward speed of the vehicle for cyclically and collectively adjusting the input to at least one of said pitch-changing means with respect to the other to reduce the negative built-in twist while the blade is advancing during forward flight of the vehicle.
Claim 3
Dependent Claim
46 words
The combination defined in claim 1 wherein said means for cyclically adjusting the input to one of said pitch-changing means with respect to the other also serves to increase the negative built-in twist of said blade while it is retreating during forward flight of the vehicle.
Claim 4
Dependent Claim
54 words
The combination defined in claim 2 wherein said second pitch-changing means comprises a servo flap pivotally mounted at said outboard blade station, linkage means carried by The rotor hub for operating said servo flap, and means including a swashplate for operating said linkage means in response to said vehicle cyclic and collective pitch controls.
Claim 5
Dependent Claim
55 words
The combination defined in claim 3 wherein said first pitch-changing means comprises a pitch horn adjacent the in board end of the blade, linkage means carried by the rotor hub for operating said pitch horn, and means including a swashplate for operating said linkage means in response to said vehicle cyclic and collective pitch controls.
Claim 6
Dependent Claim
63 words
The combination defined in claim 4 wherein said means for adjusting the inputs to said first and second pitch-changing means includes an airspeed indicator producing a pressure signal indicative of vehicle speed, transducer means for converting the pressure signal into at least one displacement signal, and boosted means for varying said pitch input to said pitch-changing means in response to said displacement signal.
Claim 7
Dependent Claim
80 words
The combination defined in claim 5 wherein said transducer means comprises means for first converting said pressure signal into an electrical signal, servo means for converting said electrical signal into an angular displacement signal, a plurality of camming devices adapted for movement in response to angular displacement of said servo means, and cam follower means for engagement with each of said camming devices for producing a predetermined linear displacement in response to a predetermined angular displacement of said servo means.
Claim 8
Dependent Claim
89 words
The combination defined in claim 6 wherein each of said swashplates includes a portion which rotates with the rotor hub and a nonrotating portion which is constrained to tilt and to move axially with respect to the axis of rotation of said rotor hub, and at least three pushrods connected to said nonrotating portion of one of said swashplates for moving said swashplate either axially or to tilt it with respect to said axis of rotation, said predetermined linear displacements being applied to said pushrods through said boosted means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-28 | 1974-12-28 | 1975-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-28 | 1978-12-28 | 1979-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-28 | 1982-12-28 | 1983-06-29 | $7700.00 | Window Closed / Lapsed |