US3857534A
Expired / Lapsed
US
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Multi-frequency helicopter vibration isolation
Assignee: Bell Helicopter Textron Inc
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Filing: 1973-04-02
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Granted: 1974-12-31
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Expires: 1993-04-02
Abstract
Abstract A helicopter load supporting structure substantially vibration free from rotor induced vibration by support from the airframe on compound beams at multi-frequency nodal points.
Inventors
- 👤 J Drees
- 👤 D Shipman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:39
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/001; B64C2027/005; Y; Y10; Y10S; Y10S416/00; Y10S416/50
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
102 words
A system for multi-frequency vibration isolation of a load in an aircraft which comprises: a. a first beam cantilever supported from said fuselage and extending longitudinally in a plane perpendicular to the direction of vibration to be isolated and exhibiting a vibration node at a primary frequency, b. a second beam cantilever supported from said primary beam in the region of said node and exhibiting a vibrational node at a location spaced from said first beam and at a frequency which is a multiple of said primary frequency, and c. linkage means supporting said load in the region of said second node.
Claim 2
Independent Claim
102 words
A system for multi-frequency vibration isolation of a load in an aircraft which comprises: a. a first beam cantilever supported from said fuselage and extending longitudinally in a plane perpendicular to the direction of vibration to be isolated and exhibiting a vibration node at a primary frequency, b. a second beam cantilever supported from said primary beam in the region of said node and exhibiting a vibrational node at a location spaced from said first beam and at a frequency which is a multiple of said primary frequency, and c. linkage means supporting said load in the region of said second node.
Claim 3
Dependent Claim
26 words
The combination set forth in claim 1 wherein the linkage to said secondary beam includes structure permitting rocking of said beam without opposition by said linkage.
Claim 4
Dependent Claim
29 words
The combination set forth in claim 1 wherein the linkage to said beam is a ball and socket linkage which permits rocking of said beam unopposed by said linkage.
Claim 5
Dependent Claim
62 words
The combination set forth in claim 1 wherein said aircraft is a helicopter having a main rotor and said first beam in vibration exhibits a node at the frequency of n per rev where n is the number of blades in said rotor and wherein said second beam in vibration exhibits a node at xn per rev where x is an integer.
Claim 6
Dependent Claim
13 words
The combination set forth in claim 4 wherein n 2 and x 3.
Claim 7
Independent Claim
142 words
A system for multi-frequency vibration isolation of the load in a helicopter having a fuselage supported in flight by a pylon drawn rotor which comprises: a. a plurality of main beams each cantilevered supported from the fuselage extending in a plane perpendicular to said pylon with each said beam tuned to vibrate in a mode such that at normal operating speed of said rotor vibration nodes occur at a point spaced from said fuselage in each of said beams, b. a secondary beam supported from each main beam in the region of said node and each exhibiting a vibrational node at a point spaced from its primary beam and at a frequency which is a multiple of said primary frequency, and c. linkages coupled to each of said secondary beams, one linkage at each secondary beam node point and supporting said load.
Claim 8
Independent Claim
142 words
A system for multi-frequency vibration isolation of the load in a helicopter having a fuselage supported in flight by a pylon drawn rotor which comprises: a. a plurality of main beams each cantilevered supported from the fuselage extending in a plane perpendicular to said pylon with each said beam tuned to vibrate in a mode such that at normal operating speed of said rotor vibration nodes occur at a point spaced from said fuselage in each of said beams, b. a secondary beam supported from each main beam in the region of said node and each exhibiting a vibrational node at a point spaced from its primary beam and at a frequency which is a multiple of said primary frequency, and c. linkages coupled to each of said secondary beams, one linkage at each secondary beam node point and supporting said load.
Claim 9
Dependent Claim
26 words
The combination set forth in claim 6 wherein each of said primary beams and said secondary beams are tuned by weights at the free ends thereof.
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) | 1977-12-30 | 1978-07-01 | 1978-12-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-30 | 1982-07-01 | 1982-12-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-30 | 1986-07-01 | 1986-12-31 | $7700.00 | Window Closed / Lapsed |