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Patent US2491733A successfully refreshed from Google Patents.
US2491733A
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Helicopter
Assignee: UNITED HELICOPTERS Inc
•
Filing: 1946-11-25
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Granted: 1949-12-20
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Expires: 1966-11-25
Abstract
No abstract record available.
Inventors
- 👤 Jr Stanley Hiller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:23
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/04; B64C27/12; B64C1/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
GB191014455A
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US2023105A
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US2030578A
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US2153610A
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Cited
US2404014A
Cited
US2368698A
Cited
GB595988A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1952-12-19 | 1953-06-20 | 1953-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1956-12-19 | 1957-06-20 | 1957-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1960-12-19 | 1961-06-20 | 1961-12-20 | $7700.00 | Window Closed / Lapsed |