US3952601A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Helicopter rotor blade balancing method
Assignee: RTX Corp
•
Filing: 1974-12-18
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Granted: 1976-04-27
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Expires: 1994-12-18
Abstract
Abstract A helicopter rotor blade having at least one ramp tab of selected span and chord dimensions, weight and shaped to define an outer surface of selected angularity with respect to the blade chord and being selectively positioned along the blade trailing edge and bonded to its upper or lower surface so as to be totally within the blade chord profile and be effective to eliminate or reduce to within acceptable limits blade pitching moment dynamic unbalance.
Inventors
- 👤 Charles V. Galli
- 👤 Robert Zincone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:23
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; B64C27/46; B64C27/473; B64C27/48; G; G01; G01M; G01M1/00; G01M1/14; G01M1/16; G01M1/30; G01M1/36; Y; Y10; Y10S; Y10S416/00; Y10S416/50
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
156 words
The method of eliminating pitching moment dynamic unbalance in a helicopter rotor blade comprising the steps of: A. whirling the blade in rotor motion fashion to determine its degree of pitching moment dynamic unbalance, B. temporarily attaching at least one ramp-shaped tab of selected weight, span dimension, chord dimension and external surface angularity with respect to the blade chord at a selected station along the blade span and at the blade trailing edge upper or lower surface so as to be positioned totally within the blade chord profile and not extend therebeyond, C. whirling the blade with the ramp tab or tabs so temporarily attached to determine blade pitching moment dynamic unbalance, D. adjusting the span dimension, span location or number of ramp tabs and rewhirling the blade until all pitching moment dynamic unbalance is eliminated or reduced to acceptable limits, and E. permanently bonding the tab or tabs so selected in the final tested position.
Claim 2
Independent Claim
156 words
The method of eliminating pitching moment dynamic unbalance in a helicopter rotor blade comprising the steps of: A. whirling the blade in rotor motion fashion to determine its degree of pitching moment dynamic unbalance, B. temporarily attaching at least one ramp-shaped tab of selected weight, span dimension, chord dimension and external surface angularity with respect to the blade chord at a selected station along the blade span and at the blade trailing edge upper or lower surface so as to be positioned totally within the blade chord profile and not extend therebeyond, C. whirling the blade with the ramp tab or tabs so temporarily attached to determine blade pitching moment dynamic unbalance, D. adjusting the span dimension, span location or number of ramp tabs and rewhirling the blade until all pitching moment dynamic unbalance is eliminated or reduced to acceptable limits, and E. permanently bonding the tab or tabs so selected in the final tested position.
Claim 3
Dependent Claim
35 words
The method according to claim 1 and the additional step of again whirling the blade with the tab or tabs so permanently bonded to determine whether blade pitching moment dynamic unbalance is within acceptable limits.
Claim 4
Dependent Claim
29 words
The method according to claim 1 wherein fine adjustments in blade pitching moment dynamic unbalance reduction or elimination is accomplished by altering the span dimension of the ramp tab.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-27 | 1979-10-27 | 1980-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-27 | 1983-10-27 | 1984-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-27 | 1987-10-27 | 1988-04-27 | $7700.00 | Window Closed / Lapsed |