Patent US2724446A successfully refreshed from Google Patents.
US2724446A
Expired / Lapsed
US
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Helicopter rotor mechanism
Assignee: Individual
•
Filing: 1953-07-07
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Granted: 1955-11-22
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Expires: 1973-07-07
Abstract
No abstract record available.
Inventors
- 👤 Keith A Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:18
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/04; B64C27/12; B64C27/16; B64C27/18
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2224357A
Cited
GB580109A
Cited
GB605085A
Cited
US2569882A
Cited
US2658575A
Cited
US2639775A
Cited
GB623582A
Cited
US2593335A
Cited
US2689011A
Cited
US2663374A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1958-11-21 | 1959-05-23 | 1959-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1962-11-21 | 1963-05-23 | 1963-11-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1966-11-21 | 1967-05-23 | 1967-11-22 | $7700.00 | Window Closed / Lapsed |