US2420823A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Helicopter
Assignee: Individual
•
Filing: 1943-10-16
•
Granted: 1947-05-20
•
Expires: 1963-10-16
Abstract
No abstract record available.
Inventors
- 👤 Russell R Hays
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:17
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/82
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1527666A
Cited
US1449129A
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US1455352A
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US1541534A
Cited
US1836406A
Cited
US1977724A
Cited
US2037745A
Cited
US2338935A
Cited
US2364096A
Cited
GB536904A
Cited
US2369652A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1950-05-19 | 1950-11-18 | 1951-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1954-05-19 | 1954-11-18 | 1955-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1958-05-19 | 1958-11-18 | 1959-05-20 | $7700.00 | Window Closed / Lapsed |