US3866857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Helicopters
Assignee: Westland Group PLC
•
Filing: 1973-06-18
•
Granted: 1975-02-18
•
Expires: 1993-06-18
Abstract
Abstract A helicopter has a main rotor system with a plurality of rotor blades and a flying control system including a collective pitch control mechanism operative to change the pitch angle of each rotor blade by an equal amount. The mechanism includes a collective pitch control lever operable in a generally vertical plane between stops within a range of minimum and maximum flying collective pitch angle settings. When desired for certain phases of operation, the stop at the minimum setting can be overcome to permit selection of a variable negative collective pitch angle setting of the rotor blades.
Inventors
- 👤 Tadeusz Leopold Ciastula
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:42
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; Y; Y10; Y10T; Y10T74/00; Y10T74/20; Y10T74/20576; Y10T74/20582; Y10T74/2063
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
123 words
A helicopter having: a main rotor system with a plurality of rotor blades, a control system including a collective pitch control means for changing the pitch angle of each rotor blade by an equal amount, said control means including a control lever operable in a generally vertical plane between opposed minimum and maximum stops which establish, respectively, minimum and maximum ends of a range of flying collective pitch angle settings, said minimum stop including means for concurrently forming said minimum stop and also permitting that minimum stop position to be overrun by movement of the said lever beyond said minimum stop position to a negative collective pitch angle setting of the rotor blades, and wherein the extent of the said overrun is variable.
Claim 2
Dependent Claim
123 words
A helicopter having: a main rotor system with a plurality of rotor blades, a control system including a collective pitch control means for changing the pitch angle of each rotor blade by an equal amount, said control means including a control lever operable in a generally vertical plane between opposed minimum and maximum stops which establish, respectively, minimum and maximum ends of a range of flying collective pitch angle settings, said minimum stop including means for concurrently forming said minimum stop and also permitting that minimum stop position to be overrun by movement of the said lever beyond said minimum stop position to a negative collective pitch angle setting of the rotor blades, and wherein the extent of the said overrun is variable.
Claim 3
Dependent Claim
28 words
A helicopter as claimed in claim 1, wherein the minimum stop comprises a resiliently maintained stop force which is overcome by pressure applied to the said control lever.
Claim 4
Dependent Claim
16 words
A helicopter as claimed in claim 2, wherein the stop force is provided by a spring.
Claim 5
Dependent Claim
15 words
A helicopter as claimed in claim 3, wherein the spring is a compressible coil spring.
Claim 6
Dependent Claim
27 words
A helicopter as claimed in claim 4, wherein the coil spring is located in a telescopic strut to normally maintain the strut at its fully extended position.
Claim 7
Dependent Claim
69 words
A helicopter as claimed in claim 5, wherein the telescopic strut is pivotally mounted between the control lever and helicopter structure so that during movement of the control lever within the minimum to maximum range the strut acts as a fixed length lever, and when the control lever is moved beyond the minimum position to the negative setting the strut is telescoped against the force of the coil spring.
Claim 8
Dependent Claim
55 words
A helicopter as claimed in claim 6, wherein the helicopter structure comprises a pivotal member mounted for movement with the telescopic strut between the range of minimum and maximum settings and associating with stop means to prevent movement of the member during movement of the control lever between the minimum and negative collective pitch settings.
Claim 9
Dependent Claim
26 words
A helicopter as claimed in claim 7, wherein the stop means is formed integral with a collective/yaw interlink mechanism operated by movement of the pivotal member.
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) | 1978-02-17 | 1978-08-19 | 1979-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-17 | 1982-08-19 | 1983-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-17 | 1986-08-19 | 1987-02-18 | $7700.00 | Window Closed / Lapsed |