Patent US2502830A successfully refreshed from Google Patents.
Patent JPS5651655A successfully refreshed from Google Patents.
Patent FR781470A successfully refreshed from Google Patents.
Patent US2749994A successfully refreshed from Google Patents.
US2749994A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Lift rotor construction for tandem rotor helicopters
Assignee: Individual
•
Filing: 1951-04-03
•
Granted: 1956-06-12
•
Expires: 1971-04-03
Abstract
No abstract record available.
Inventors
- 👤 Apostolescu Stefan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:17
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/54
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US1023233A
Cited
US1076803A
Cited
US1009770A
Cited
US1237318A
Cited
US1705489A
Cited
US1792758A
Cited
US1957277A
Cited
US2348249A
Cited
US2385464A
Cited
US2333555A
Cited
US2372481A
Cited
US2410239A
Cited
US2389798A
Cited
US2384445A
Cited
US2529479A
Cited
US2655997A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1959-06-12 | 1959-12-12 | 1960-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1963-06-12 | 1963-12-12 | 1964-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1967-06-12 | 1967-12-12 | 1968-06-12 | $7700.00 | Window Closed / Lapsed |