Patent US2644537A successfully refreshed from Google Patents.
US2644537A
Expired / Lapsed
US
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Spar type rotor blade
Assignee: Boeing Helicopters Co
•
Filing: 1947-05-02
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Granted: 1953-07-07
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Expires: 1967-05-02
Abstract
No abstract record available.
Inventors
- 👤 Donald N Meyers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:33
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/32; B64C27/46; B64C27/473
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US2121052A
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US2152861A
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US2056592A
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US2183158A
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US2394445A
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US2303707A
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US2467031A
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US2470056A
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US2484141A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-07-06 | 1957-01-05 | 1957-07-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-07-06 | 1961-01-05 | 1961-07-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-07-06 | 1965-01-05 | 1965-07-07 | $7700.00 | Window Closed / Lapsed |