US3795375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for continuously trimming helicopter rotor blades during flight
Assignee: Kaman Aerospace Corp
•
Filing: 1972-05-22
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Granted: 1974-03-05
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Expires: 1992-05-22
Abstract
Abstract A vibration sensor is mounted on the air frame to provide a continuous output proportional to the unbalance of the rotor blades with respect to one another. This output is fed to a trim tab on the particular blade causing the unbalance to alter that blade''s lift slightly until the balance is reduced to an acceptable level.
Inventors
- 👤 A Lemnios
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:13
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/001; B64C27/54; B64C27/72; B64C2027/7205; B64C2027/7261; B64C2027/7266; Y; Y02; Y02T; Y02T50/00; Y02T50/30
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
118 words
In combination with a rotary wing aircraft which includes an airframe having a longitudinal axis and a plurality of rotor blades which blades are capable of control in flight by a control lever through a primary flight blade control mechanism: a vibration transducer mounted to the airframe and located on said airframe axis for sensing once per revolution pitching moment transients and generating an output in response thereto, a trim tab on at least one of said rotor blades, an actuator mechanically connected to said blade mounted trim tab for altering the lift contribution of that blade independently of said primary flight control mechanism, and means for energizing said actuator in response to tHe output of said transducer.
Claim 2
Dependent Claim
118 words
In combination with a rotary wing aircraft which includes an airframe having a longitudinal axis and a plurality of rotor blades which blades are capable of control in flight by a control lever through a primary flight blade control mechanism: a vibration transducer mounted to the airframe and located on said airframe axis for sensing once per revolution pitching moment transients and generating an output in response thereto, a trim tab on at least one of said rotor blades, an actuator mechanically connected to said blade mounted trim tab for altering the lift contribution of that blade independently of said primary flight control mechanism, and means for energizing said actuator in response to tHe output of said transducer.
Claim 3
Dependent Claim
63 words
The combination of claim 1 wherein said means for energizing said actuator comprises an electric circuit which includes slip ring and brush means between said airframe and said rotor blades for selectively energizing said trim tab actuator motor when said blade is in a particular position with respect to the longitudinal axis of the airframe and hence to the location of said transducer.
References Cited (Backward Citations)
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Cited
US2892502A
Cited
US2921289A
Cited
US2960168A
Cited
US3482805A
Cited
US3658280A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |