Patent US2684722A successfully refreshed from Google Patents.
US2684722A
Expired / Lapsed
US
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Helicopter rotor structure
Assignee: Individual
•
Filing: 1952-05-22
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Granted: 1954-07-27
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Expires: 1972-05-22
Abstract
No abstract record available.
Inventors
- 👤 John A Perry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:23
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/54; B64C27/58; B64C27/59; B64C27/625; B64C27/32; B64C27/37; B64C27/41; B64C27/43
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-07-26 | 1958-01-25 | 1958-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-07-26 | 1962-01-25 | 1962-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-07-26 | 1966-01-25 | 1966-07-27 | $7700.00 | Window Closed / Lapsed |